JP4134136B2 - Angular velocity sensor - Google Patents

Description

  The present invention relates to an angular velocity sensor, and more particularly to an angular velocity sensor that can detect an angular velocity around a predetermined axis in an XYZ three-dimensional coordinate system.

  In the automobile industry and the machine industry, there is an increasing demand for sensors that can accurately detect the acceleration and angular velocity of moving objects. In general, acceleration in an arbitrary direction and an angular velocity in an arbitrary rotation direction act on an object that freely moves in a three-dimensional space. Therefore, in order to accurately grasp the motion of the object, it is necessary to independently detect the acceleration for each coordinate axis direction and the angular velocity around each coordinate axis in the XYZ three-dimensional coordinate system.

Conventionally, various multidimensional acceleration sensors have been proposed. For example, Patent Document 1 below discloses an acceleration sensor that uses a resistance element formed on a semiconductor substrate and detects the applied acceleration for each coordinate axis direction. Patent Document 2 discloses a multi-axis acceleration sensor having a self-diagnosis function. Furthermore, Patent Document 3 discloses an acceleration sensor that uses a capacitance element or a piezoelectric element and detects applied acceleration for each coordinate axis direction. Patent Documents 4 and 5 also disclose similar multi-axis acceleration sensors. Patent Document 6 discloses a novel electrode arrangement in a similar multi-axis acceleration sensor, and Patent Document 7 discloses a multi-axis acceleration sensor using another type of piezoelectric element. The characteristics of these acceleration sensors are that a plurality of resistance elements / capacitance elements / piezoelectric elements are arranged at predetermined positions on a flexible substrate, and the resistance value of the resistance element changes / capacitance of the capacitance element. The point is to detect the applied acceleration based on the change in value / change in the voltage generated by the piezoelectric element. A weight body is attached to the flexible substrate. When acceleration is applied, force is applied to the weight body, and the flexible substrate is bent. If this deflection is detected based on the above-described change in resistance value / capacitance value / generated charge, each axial component of acceleration can be obtained.
International Publication No. WO 88/08522 (US Pat. No. 4,967,605 / No. 5,182,515) International Publication No. WO91 / 10118 (US Pat. No. 5,295,386) International Publication No. WO92 / 17759 (US Pat. No. 5,492,020) JP-A-4-148833 JP-A-4-249726 (US Pat. No. 5,421,213) Japanese Patent Laid-Open No. 5-118942 (US Pat. No. 5,343,765) International Publication No. WO93 / 02342

  On the other hand, the literature about a multidimensional angular velocity sensor cannot be found as far as the present inventors know. Normally, the angular velocity sensor is used to detect an angular velocity such as a power axis of a vehicle, and has only a function of detecting an angular velocity around a specific one axis. When obtaining the rotational speed of such a power shaft, it is sufficient to use a one-dimensional angular velocity sensor. However, in order to detect the angular velocity of an object that freely moves in a three-dimensional space, it is necessary to independently detect the angular velocities around the X, Y, and Z axes in the XYZ three-dimensional coordinate system. . To detect the angular velocities around each of the X, Y, and Z axes using a one-dimensional angular velocity sensor that has been used in the past, three sets of angular velocity sensors are prepared, and the angular velocities around each axis are prepared. It must be mounted in a specific direction so that it can be detected. For this reason, the structure as a whole becomes complicated and the cost becomes high.

  An object of the present invention is to provide a novel angular velocity sensor having a relatively simple structure and capable of independently detecting an angular velocity around a predetermined axis in an XYZ three-dimensional coordinate system.

  The basic principle utilized in the present invention is that when an angular velocity ω around the first coordinate axis is acting on a vibrator placed in an XYZ three-dimensional coordinate system, the vibrator is moved in the second coordinate axis direction. This is based on the principle that when it is vibrated, a Coriolis force proportional to the magnitude of the angular velocity ω is generated in the direction of the third coordinate axis. In order to detect the angular velocity ω using this principle, means for vibrating the vibrator in a predetermined coordinate axis direction and means for detecting a displacement in the predetermined coordinate axis direction generated in the vibrator due to the action of the Coriolis force are: I need it. Moreover, in order to detect all of the angular velocity ωx around the X axis, the angular velocity ωy around the Y axis, and the angular velocity ωz around the Z axis, means for vibrating the vibrator in three axes, and the three axis directions generated in the vibrator And means for detecting the displacement of. The present invention provides a sensor provided with such means, and has the following characteristics.

(1) A first feature of the present invention is a one-dimensional angular velocity sensor that detects an angular velocity around the Y axis in an XYZ three-dimensional coordinate system.
A piezoelectric element;
A plurality of upper electrodes formed on the upper surface of the piezoelectric element;
A plurality of lower electrodes formed on the lower surface of the piezoelectric element and disposed at positions facing each of the plurality of upper electrodes;
A flexible substrate fixed to the lower surface of the lower electrode and having flexibility;
A vibrator fixed to the lower surface of the flexible substrate;
A sensor housing that supports the flexible substrate and accommodates the vibrator;
Excitation means for vibrating the vibrator in a predetermined direction by supplying an AC signal between a predetermined lower electrode and an upper electrode facing each other;
Detecting means for detecting displacement of the vibrator in a predetermined direction by obtaining a voltage generated between a predetermined lower electrode and an upper electrode facing each other;
Provided,
Define an XYZ three-dimensional coordinate system in which the origin of the coordinate system is taken at the approximate center of the flexible substrate, and the X and Y axes intersect on a plane parallel to the principal surface of the flexible substrate. When defining an arbitrary W axis (not overlapping with the Y axis) that intersects the X axis at the origin position,
Of the plurality of upper electrodes, the first upper electrode is formed at a position where the projected image on the XY plane is at the negative portion of the X axis, and the second upper electrode is projected on the XY plane with the X axis Formed in the positive part,
Of the plurality of upper electrodes, the third upper electrode is formed at a position where the projected image on the XY plane comes to the negative part of the W axis, and the fourth upper electrode has a projected image on the XY plane of the W axis. Formed in the positive part,
The excitation means performs a process of vibrating the vibrator in the X-axis direction by supplying an AC signal having a predetermined phase between the first and second upper electrodes and the lower electrodes facing the first and second upper electrodes.
The detection means detects the displacement of the vibrator in the Z-axis direction based on the voltage generated between the third and fourth upper electrodes and the respective lower electrodes facing the third and fourth upper electrodes, and the detected displacement is detected in the Y-axis. A value indicating the angular velocity around is output.

(2) A second feature of the present invention is a one-dimensional angular velocity sensor that detects an angular velocity around the Z axis in an XYZ three-dimensional coordinate system.
  A piezoelectric element;
  A plurality of upper electrodes formed on the upper surface of the piezoelectric element;
  A plurality of lower electrodes formed on the lower surface of the piezoelectric element and disposed at positions facing each of the plurality of upper electrodes;
  A flexible substrate fixed to the lower surface of the lower electrode and having flexibility;
  A vibrator fixed to the lower surface of the flexible substrate;
  A sensor housing that supports the flexible substrate and accommodates the vibrator;
  Excitation means for vibrating the vibrator in a predetermined direction by supplying an AC signal between a predetermined lower electrode and an upper electrode facing each other;
  Detecting means for detecting displacement of the vibrator in a predetermined direction by obtaining a voltage generated between a predetermined lower electrode and an upper electrode facing each other;
  Provided,
  When defining an XYZ three-dimensional coordinate system in which the origin of the coordinate system is taken at the substantially central portion of the flexible substrate and the X axis and the Y axis intersect on a plane parallel to the principal surface of the flexible substrate,
  Of the plurality of upper electrodes, the first upper electrode is formed at a position where the projected image on the XY plane is at the negative portion of the X axis, and the second upper electrode is projected on the XY plane with the X axis Formed in the positive part,
  Among the plurality of upper electrodes, the third upper electrode is formed at a position where the projected image on the XY plane is at the negative portion of the Y axis, and the fourth upper electrode is projected on the XY plane with the Y axis Formed in the positive part,
  The excitation means performs a process of vibrating the vibrator in the Y-axis direction by supplying an AC signal having a predetermined phase between the third and fourth upper electrodes and the lower electrodes facing the third and fourth upper electrodes.
  The detecting means detects a displacement of the vibrator in the X-axis direction based on a voltage generated between the first and second upper electrodes and the respective lower electrodes opposed to the first and second upper electrodes, and the detected displacement is detected in the Z-axis. A value indicating the angular velocity around is output.

(3) A third feature of the present invention is a one-dimensional angular velocity sensor that detects an angular velocity around the X axis in an XYZ three-dimensional coordinate system.
A piezoelectric element;
A plurality of upper electrodes formed on the upper surface of the piezoelectric element;
A plurality of lower electrodes formed on the lower surface of the piezoelectric element and disposed at positions facing each of the plurality of upper electrodes;
A flexible substrate fixed to the lower surface of the lower electrode and having flexibility;
A vibrator fixed to the lower surface of the flexible substrate;
A sensor housing that supports the flexible substrate and accommodates the vibrator;
Excitation means for vibrating the vibrator in a predetermined direction by supplying an AC signal between a predetermined lower electrode and an upper electrode facing each other;
Detecting means for detecting displacement of the vibrator in a predetermined direction by obtaining a voltage generated between a predetermined lower electrode and an upper electrode facing each other;
Provided,
Define an XYZ three-dimensional coordinate system in which the origin of the coordinate system is taken at the approximate center of the flexible substrate, and the X and Y axes intersect on a plane parallel to the principal surface of the flexible substrate. When defining an arbitrary W axis (not overlapping with the X axis) that intersects the Y axis at the origin,
Of the plurality of upper electrodes, the first upper electrode is formed at a position where the projected image on the XY plane comes to a negative portion of the W axis, and the second upper electrode has a projected image on the XY plane of the W axis. Formed in the positive part,
Among the plurality of upper electrodes, the third upper electrode is formed at a position where the projected image on the XY plane is at the negative portion of the Y axis, and the fourth upper electrode is projected on the XY plane with the Y axis Formed in the positive part,
The excitation means performs a process of vibrating the vibrator in the Z-axis direction by supplying an AC signal having a predetermined phase between the first and second upper electrodes and the respective lower electrodes opposed to the first and second upper electrodes,
The detecting means detects the displacement of the vibrator in the Y-axis direction based on the voltage generated between the third and fourth upper electrodes and the respective lower electrodes opposed to the third and fourth upper electrodes, and detects the detected displacement as the X-axis. A value indicating the angular velocity around is output.

(4) A fourth feature of the present invention is the angular velocity sensor according to the first to third features described above,
At least one of the first upper electrode and the first lower electrode is constituted by a pair of electrodes that are physically separated from each other,
At least one of the second upper electrode and the second lower electrode is constituted by a pair of electrodes arranged physically apart from each other,
At least one of the third upper electrode and the third lower electrode is constituted by a pair of electrodes that are physically separated from each other,
At least one of the fourth upper electrode and the fourth lower electrode is configured by a pair of electrodes that are physically separated from each other.

(5) A fifth feature of the present invention is the angular velocity sensor according to the first to fourth features described above,
A plurality of physically divided piezoelectric elements are used.

(6) A sixth aspect of the present invention is directed to an angular velocity sensor according to the first to fifth features described above,
Either one of the plurality of lower electrodes or the plurality of upper electrodes is constituted by a single electrode layer.

The physical structure of the angular velocity sensor according to the present invention is based on the structure exemplified as “Section 5: Fifth Example” described later. However, in the following description, “Section 0: Basic principle” will be described as the basic principle of angular velocity detection according to the present invention, and in the following “Section 1” to “Section 4”, reference examples using the basic principle (the present invention). Although the physical structure is different from that of the angular velocity sensor according to FIG. Although these reference examples are different in physical structure from the angular velocity sensor according to the present invention, for convenience, these reference examples will also be described using the word “example”.

<<< Section 0 Basic Principles >>>
<0.1> Uniaxial angular velocity sensor

First, the principle of detection of angular velocity by a uniaxial angular velocity sensor that is the basis of the multiaxial angular velocity sensor according to the present invention will be briefly described. FIG. 1 is a diagram showing the basic principle of an angular velocity sensor disclosed on page 60 of a magazine “THE invention”, vol. 90, No. 3 (1993), supervised by the Japan Patent Office. Consider an XYZ three-dimensional coordinate system in which a prismatic vibrator 10 is prepared and X, Y, and Z axes are defined in directions as shown. In such a system, it is known that the following phenomenon occurs when the vibrator 10 is rotating at an angular velocity ω with the Z axis as a rotation axis. That is, when a vibration U that causes the vibrator 10 to reciprocate in the X-axis direction is applied, a Coriolis force F is generated in the Y-axis direction. In other words, if the vibrator 10 is rotated about the Z axis while the vibrator 10 is vibrated along the X axis in the figure, a Coriolis force F is generated in the Y axis direction. This phenomenon is a dynamic phenomenon that has long been known as the Foucault pendulum. The generated Coriolis force F is
F = 2m ・ v ・ ω
It is represented by Here, m is the mass of the vibrator 10, v is the instantaneous speed of vibration of the vibrator 10, and ω is the instantaneous angular speed of the vibrator 10.

  The uniaxial angular velocity sensor disclosed in the aforementioned magazine detects the angular velocity ω by utilizing this phenomenon. That is, as shown in FIG. 1, the first piezoelectric element 11 is provided on the first surface of the prismatic vibrator 10, and the second piezoelectric element is provided on the second surface orthogonal to the first surface. 12 are each attached. As the piezoelectric elements 11 and 12, plate-shaped elements made of piezoelectric ceramic are used. The piezoelectric element 11 is used to apply the vibration U to the vibrator 10, and the piezoelectric element 12 is used to detect the generated Coriolis force F. That is, when an AC voltage is applied to the piezoelectric element 11, the piezoelectric element 11 repeatedly expands and contracts and vibrates in the X-axis direction. This vibration U is transmitted to the vibrator 10, and the vibrator 10 vibrates in the X-axis direction. In this way, when the vibrator 10 itself rotates at the angular velocity ω with the Z axis as the central axis in a state where the vibration U is applied to the vibrator 10, the Coriolis force F is generated in the Y axis direction due to the phenomenon described above. Since this Coriolis force F acts in the thickness direction of the piezoelectric element 12, a voltage V proportional to the Coriolis force F is generated on both surfaces of the piezoelectric element 12. Therefore, by measuring this voltage V, the angular velocity ω can be detected.

<0.2> Multi-Axis Angular Velocity Sensor The conventional angular velocity sensor described above is for detecting the angular velocity around the Z axis, and cannot detect the angular velocity around the X axis or the Y axis. In the present invention, as shown in FIG. 2, the angular velocity ωx around the X axis, the angular velocity ωy around the Y axis, and the angular velocity ωz around the Z axis in the XYZ three-dimensional coordinate system are separately set for the predetermined object 20. Thus, a multi-axis angular velocity sensor that can be detected is provided. The basic principle will be described with reference to FIGS. Now, it is assumed that the vibrator 30 is placed at the origin position of the XYZ three-dimensional coordinate system. In order to detect the angular velocity ωx around the X axis of the vibrator 30, as shown in FIG. 3, the Coriolis force generated in the Y axis direction when a vibration Uz in the Z axis direction is applied to the vibrator 30. What is necessary is just to measure Fy. The Coriolis force Fy is a value proportional to the angular velocity ωx. Further, in order to detect the angular velocity ωy around the Y axis of the vibrator 30, as shown in FIG. 4, it is generated in the Z axis direction when a vibration Ux in the X axis direction is applied to the vibrator 30. What is necessary is just to measure the Coriolis force Fz. The Coriolis force Fz is a value proportional to the angular velocity ωy. Further, in order to detect the angular velocity ωz around the Z-axis of the vibrator 30, as shown in FIG. 5, it is generated in the X-axis direction when a vibration Uy in the Y-axis direction is applied to the vibrator 30. What is necessary is just to measure the Coriolis force Fx. The Coriolis force Fx is a value proportional to the angular velocity ωz.

  After all, in order to detect the angular velocity for each axis in the XYZ three-dimensional coordinate system, a mechanism for vibrating the vibrator 30 in the X-axis direction, a mechanism for vibrating in the Y-axis direction, and a mechanism for vibrating in the Z-axis direction A mechanism for detecting the Coriolis force Fx in the X-axis direction acting on the vibrator 30, a mechanism for detecting the Coriolis force Fy in the Y-axis direction, and a mechanism for detecting the Coriolis force Fz in the Z-axis direction are required. .

<0.3> Vibration Mechanism / Detection Mechanism As described above, in the multi-axis angular velocity sensor according to the present invention, a mechanism for vibrating the vibrator in a specific coordinate axis direction, and a specific coordinate axis direction acting on the vibrator. A mechanism for detecting Coriolis force is required. The following mechanisms can be used as the vibration mechanism.

  (1) Mechanism using Coulomb force: A first electrode is formed on the vibrator side and a second electrode is formed on the sensor housing side, and the pair of electrodes are arranged to face each other. If charges of the same polarity are supplied to both electrodes, a repulsive force acts, and if charges of different polarities are supplied, an attractive force acts. Therefore, if a repulsive force and a suction force are alternately applied between both electrodes, the vibrator vibrates with respect to the sensor housing.

  (2) Mechanism using a piezoelectric element: This mechanism is used in the uniaxial angular velocity sensor shown in FIG. By supplying an AC voltage to the piezoelectric element 11, the vibrator 10 is vibrated.

  (3) Mechanism using electromagnetic force: A vibrator made of a magnetic material is used, a coil is arranged on the sensor casing side, and an electric current is applied to this coil to cause the electromagnetic force to vibrate.

  On the other hand, the following mechanisms can be used as the Coriolis force detection mechanism.

  (1) Mechanism using change in electrostatic capacitance: A first electrode is formed on the vibrator side, a second electrode is formed on the sensor housing side, and the pair of electrodes are arranged to face each other. When the Coriolis force acts on the vibrator and displacement occurs, the distance between the two electrodes changes, so that the capacitance value of the capacitive element constituted by both electrodes changes. By measuring the change in the capacitance value, the applied Coriolis force is detected.

  (2) Mechanism using a piezoelectric element: This mechanism is used in the uniaxial angular velocity sensor shown in FIG. When the Coriolis force F acts on the piezoelectric element 12, the piezoelectric element 12 generates a voltage proportional to the Coriolis force F. The generated Coriolis force is detected by measuring this generated voltage.

  (3) Mechanism using a differential transformer: Using a vibrator made of a magnetic material, a coil is placed on the sensor housing side. When Coriolis force acts on the vibrator and displacement occurs, the distance between the vibrator and the coil changes, so that the inductance of the coil changes. The measured Coriolis force is detected by measuring the change in inductance.

  (4) Mechanism using a piezoresistive element: A substrate that is bent by the action of Coriolis force is provided. A piezoresistive element is formed on the substrate, and the deflection generated on the substrate is detected as a change in the resistance value of the piezoresistive element. That is, the acting Coriolis force is detected by measuring the change in resistance value.

  The basic principle of the multi-axis angular velocity sensor according to the present invention has been briefly described above. Specific examples of the sensor having a simple structure that operates based on such a basic principle will be described in detail below.

<<< Section 1 First Example >>>
<1.1> Structure of Sensor According to First Example First, a multi-axis angular velocity sensor according to a first example of the present invention will be described. The first embodiment is a sensor that uses a mechanism that uses Coulomb force as a vibration mechanism and a mechanism that uses a change in capacitance as a detection mechanism.

  FIG. 6 is a sectional side view of the multi-axis angular velocity sensor according to the first embodiment. The flexible substrate 110 and the fixed substrate 120 are both disk-shaped substrates and are arranged in parallel to each other with a predetermined interval. A columnar vibrator 130 is fixed to the lower surface of the flexible substrate 110. Further, the outer peripheral portion of the flexible substrate 110 and the outer peripheral portion of the fixed substrate 120 are both supported by the sensor housing 140. Five upper electrode layers E1 to E5 (only part of which are shown in FIG. 6) are formed on the lower surface of the fixed substrate 120. Similarly, the upper surface of the flexible substrate 110 has 5 A plurality of lower electrode layers F1 to F5 (only a part of which is shown) are formed. Here, the fixed substrate 120 has sufficient rigidity and does not bend, but the flexible substrate 110 has flexibility and functions as a so-called diaphragm. The vibrator 130 is made of a material having a weight sufficient to generate stable vibration. Here, for convenience of explanation, an XYZ three-dimensional coordinate system having the center of gravity O of the vibrator 130 as an origin is used. I will think about it. That is, an X axis is defined in the right direction of the drawing, a Z axis is defined in the upward direction, and a Y axis is defined in a direction perpendicular to the paper surface. FIG. 6 is a sectional view of the sensor cut along the XZ plane. In this embodiment, the flexible substrate 110 and the fixed substrate 120 are both made of an insulating material. When these substrates are made of a conductive material such as metal, each electrode layer may be formed via an insulating film so that the electrode layers are not short-circuited.

  The shape and arrangement of the lower electrode layers F1 to F5 are clearly shown in FIG. FIG. 7 is a top view of the flexible substrate 110, and clearly shows that the fan-shaped lower electrode layers F1 to F4 and the circular lower electrode layer F5 are arranged. On the other hand, the shape and arrangement of the upper electrode layers E1 to E5 are clearly shown in FIG. FIG. 8 is a bottom view of the fixed substrate 120 and clearly shows that the fan-shaped upper electrode layers E1 to E4 and the circular upper electrode layer E5 are arranged. The upper electrode layers E1 to E5 and the lower electrode layers F1 to F5 have the same shape, and are formed at positions facing each other. Therefore, a capacitive element is formed by a pair of opposing electrode layers, and a total of five sets of capacitive elements are formed. Here, these will be referred to as capacitance elements C1 to C5, respectively. For example, an element formed by the upper electrode layer E1 and the lower electrode layer F1 is referred to as a capacitance element C1.

<1.2> Vibration mechanism of vibrator Now, what kind of phenomenon occurs when voltage is supplied between predetermined electrode layers of this sensor will be examined. First, consider a case where a predetermined voltage is applied between the electrode layers E1 and F1. For example, as shown in FIG. 9, when a voltage is supplied so that the electrode layer E1 side is positive and the F1 side is negative, an attractive force based on Coulomb force acts between both electrode layers. As described above, the flexible substrate 110 is a flexible substrate, and bending is caused by such a suction force. That is, as shown in FIG. 9, the flexible substrate 110 is mechanically deformed so that the distance between the electrode layers E1 and F1 to which a voltage is applied is reduced. When such a mechanical deformation occurs in the flexible substrate 110, the vibrator 130 is displaced by ΔX in the positive direction of the X axis.

  Next, consider a case where a predetermined voltage is applied between the electrode layers E2 and F2. For example, as shown in FIG. 10, when a voltage is supplied so that the electrode layer E2 side is positive and the F2 side is negative, an attractive force acts between them, and the distance between the electrode layers E2 and F2 is reduced. The flexible substrate 110 is mechanically deformed. As a result, the vibrator 130 is displaced by ΔX in the negative direction of the X axis. After all, when a voltage is applied between the electrode layers E1 and F1, the vibrator 130 is displaced in the positive direction of the X axis, and when a voltage is applied between the electrode layers E2 and F2, the vibrator 130 is negative of the X axis. Will be displaced in the direction of. Therefore, if the voltage application between the electrode layers E1 and F1 and the voltage application between the electrode layers E2 and F2 are alternately performed, the vibrator 130 can be reciprocated in the X-axis direction.

  By the way, as shown in FIGS. 7 and 8, the electrode layers E1, F1, E2, and F2 described above are electrode layers arranged on the X axis. In contrast, the electrode layers E3, F3, E4, and F4 are disposed on the Y axis. Accordingly, if the voltage application between the electrode layers E3 and F3 and the voltage application between the electrode layers E4 and F4 are alternately performed, it is easy to reciprocate the vibrator 130 in the Y-axis direction. You can understand.

  Next, consider a case where a predetermined voltage is applied between the electrode layers E5 and F5. For example, as shown in FIG. 11, when a voltage is supplied so that the electrode layer E5 side is positive and the F5 side is negative, an attractive force acts between them, and the distance between the electrode layers E5 and F5 is reduced. The flexible substrate 110 is mechanically deformed. Since the electrode layers E5 and F5 are both located at the center of each substrate, the flexible substrate 110 is not tilted, and a displacement that translates in the Z-axis direction occurs. As a result, the vibrator 130 is displaced by ΔZ in the positive direction of the Z axis. When the voltage application to both electrode layers E5 and F5 is stopped, the vibrator 130 returns to the original position (position shown in FIG. 6). Therefore, if voltage application to both electrode layers E5 and F5 is intermittently performed, the vibrator 130 can be reciprocated in the Z-axis direction.

  As described above, the vibrator 130 can be vibrated along the X axis, the Y axis, and the Z axis by applying a voltage to the specific electrode layer set at a specific timing. In the above description, a positive voltage is applied to the upper electrode layers E1 to E5 and a negative voltage is applied to the lower electrode layers F1 to F5. Happens.

  Eventually, in order to cause the vibrator 130 to vibrate in the X-axis direction, a voltage V1 having a waveform as shown in FIG. 12 is supplied between the electrode layers E1 and F1, and the voltage V2 is applied to the electrode layers E2 and E2. What is necessary is just to supply between F2. If a voltage having such a waveform is supplied, a displacement ΔX as shown in FIG. 9 is generated in the vibrator 130 in the periods t1, t3, and t5, and the vibrator 130 is shown in FIG. 10 in the periods t2 and t4. Such a displacement −ΔX occurs. Similarly, in order to cause the vibrator 130 to vibrate in the Y-axis direction, a voltage V3 having a waveform as shown in FIG. 13 is supplied between the electrode layers E3 and F3, and the voltage V4 is applied to the electrode layer E4. , F4 may be supplied. Further, in order to cause the vibration Uz in the Z-axis direction of the vibrator 130, a voltage V5 having a waveform as shown in FIG. 14 may be supplied between the electrode layers E5 and F5. If the voltage V5 having such a waveform is supplied, a displacement ΔZ as shown in FIG. 11 is generated in the vibrator 130 in the periods t1, t3, and t5, and the vibrator 130 is moved to the flexible substrate 110 in the periods t2 and t4. 6 returns to the position shown in FIG. 6 (at this time, a displacement −ΔZ corresponding to the inertial force is generated).

<1.3> Coriolis force detection mechanism
1.3.1 Coriolis Force Based on Angular Velocity ωx Around the X-Axis Next, a mechanism for detecting the Coriolis force acting on this sensor using the change in capacitance will be described. First, let us consider the phenomenon when the angular velocity ωx around the X-axis acts on this sensor. For example, when the object 20 shown in FIG. 2 is rotating around the X axis at an angular velocity ωx, if this sensor is mounted on the object 20, the angular velocity ωx around the X axis with respect to the vibrator 130. Will act. By the way, as described in FIG. 3, when the vibration Uz in the Z-axis direction is applied to the vibrator in the state where the angular velocity ωx around the X-axis is acting, the Coriolis force Fy is generated in the Y-axis direction. . Therefore, if a voltage V5 having a waveform as shown in FIG. 14 is supplied between the electrode layers E5 and F5 of this sensor and a vibration Uz in the Z-axis direction is applied to the vibrator 130, a Coriolis force is exerted in the Y-axis direction. Fy should occur.

  FIG. 15 is a side sectional view showing a state in which the flexible substrate 110 is mechanically deformed by the Coriolis force Fy. When the entire sensor rotates at an angular velocity ωx about the X axis (direction perpendicular to the paper surface in the figure), when the vibrator 130 is vibrated in the Z axis direction, a Coriolis force Fy is generated in the Y axis direction. A force is applied to move the vibrator 130 in the Y-axis direction. By this force, the flexible substrate 110 is deformed as shown in the figure. Such deformation biased in the Y-axis direction is not caused by the Coulomb force between the electrode layers but is caused by the Coriolis force Fy. Regarding the applied voltage between the electrode layers, as described above, only the voltage V5 as shown in FIG. 14 is supplied between the electrode layers E5 and F5, and no voltage is supplied between the other electrode layers. Not. Here, since the generated Coriolis force Fy is proportional to the angular velocity ωx, the angular velocity ωx can be detected if the value of the Coriolis force Fy can be measured.

  Therefore, the Coriolis force Fy is measured by the following method using the change in capacitance. Consider the distance between the upper electrode layers E1 to E5 and the lower electrode layers F1 to F5. Since the vibrator 130 vibrates in the vertical direction in FIG. 15, the distance between the electrode layers repeatedly repeats shrinking and widening. Accordingly, the capacitance values (denoted by the same reference symbols C1 to C5) of the capacitive elements C1 to C5 configured by the upper electrode layers E1 to E5 and the lower electrode layers F1 to F5 are periodically increased or decreased. Will be repeated. However, due to the action of the Coriolis force Fy, the flexible substrate 110 always undergoes deformation biased in the Y-axis direction, and the vibrator 130 vibrates up and down while maintaining such deformation. That is, the electrode interval of the capacitive element C3 is always smaller than the electrode interval of the capacitive element C4, and the relationship of C3> C4 is always maintained between the capacitance value C3 and the capacitance value C4. Since the difference ΔC34 between the capacitance values C3 and C4 depends on the degree of deviation in the Y-axis direction, it is an amount indicating the magnitude of the Coriolis force Fy. In other words, the greater the Coriolis force Fy, the greater the difference ΔC34.

  The procedure for detecting the angular velocity ωx about the X axis described above is summarized as follows. First, a voltage V5 having a waveform as shown in FIG. 14 is supplied between the electrode layers E5 and F5 to give a vibration Uz in the Z-axis direction to the vibrator 130. The capacitance values of the capacitive elements C3 and C4 at that time The difference ΔC34 is obtained. The difference ΔC34 obtained in this way becomes the detected value of the angular velocity ωx obtained. Since the electrode layers E5 and F5 used for applying vibration and the electrode layers E3, F3, E4 and F4 used for measuring the difference in capacitance value are electrically completely independent, the vibration mechanism and detection There is no interference with the mechanism.

1.3.2 Coriolis force based on angular velocity ωy around the Y axis Next, let us consider the phenomenon when the angular velocity ωy around the Y axis acts on this sensor. As described with reference to FIG. 4, when the vibration Ux in the X-axis direction is applied to the vibrator in the state where the angular velocity ωy around the Y-axis is acting, the Coriolis force Fz is generated in the Z-axis direction. Accordingly, voltage V1 and voltage V2 having waveforms as shown in FIG. 12 are supplied between the electrode layers E1 and F1 and between the electrode layers E2 and F2 of the sensor, and the vibration Ux in the X-axis direction is supplied to the vibrator 130. , Coriolis force Fz should be generated in the Z-axis direction.

  FIG. 16 is a side sectional view showing a state in which the flexible substrate 110 is mechanically deformed by the Coriolis force Fz. When the entire sensor is rotated at an angular velocity ωy about the Y axis (the direction perpendicular to the drawing sheet), if the vibrator 130 is vibrated in the X axis direction, a Coriolis force Fz is generated in the Z axis direction. A force is applied to move the vibrator 130 in the Z-axis direction. By this force, the flexible substrate 110 is deformed as shown in the figure. Such deformation biased in the Z-axis direction is not caused by the Coulomb force between the electrode layers but is caused by the Coriolis force Fz. Regarding the applied voltage between the electrode layers, as described above, only the voltages V1 and V2 as shown in FIG. 12 are supplied between the electrode layers E1, F1, E2 and F2, and between the other electrode layers. No voltage is supplied. Here, since the generated Coriolis force Fz is proportional to the angular velocity ωy, the angular velocity ωy can be detected if the value of the Coriolis force Fz can be measured.

  The value of the Coriolis force Fz can be obtained based on the capacitance value C5 of the capacitive element C5 formed by the upper electrode layer E5 and the lower electrode layer F5. This is because if the Coriolis force Fz increases, the distance between the two electrode layers decreases and the capacitance value C5 increases, and conversely, if the Coriolis force Fz decreases, the distance between the two electrode layers increases and the capacitance value C5 decreases. It is because it is obtained. Although the vibrator 130 vibrates in the X-axis direction, the vibration Ux does not affect the measurement of the capacitance value C5. When the vibrator 130 is displaced in the positive or negative direction of the X axis, the upper electrode layer E5 and the lower electrode layer F5 are in a non-parallel state, but the distance between the two electrode layers is partially reduced and partially reduced. As a whole, the vibration Ux does not affect the capacitance value C5.

  The detection procedure of the angular velocity ωy about the Y axis described above is summarized as follows. First, the voltage V1 and the voltage V2 having waveforms as shown in FIG. 12 are supplied between the electrode layers E1, F1, E2, and F2 to give the vibrator 130 the vibration Ux in the X-axis direction. Obtain the capacitance value of C5. The capacitance value C5 obtained in this way becomes the detected value of the angular velocity ωy obtained. Since the electrode layers E1, F1, E2, and F2 used for applying vibration and the electrode layers E5 and F5 used for measuring the capacitance value are completely independent of each other, the vibration mechanism and the detection mechanism are There is no interference between the two.

1.3.3 Coriolis force based on angular velocity ωz around the Z axis Finally, let us consider the phenomenon when the angular velocity ωz around the Z axis acts on this sensor. As described with reference to FIG. 5, when the vibration Uy in the Y-axis direction is applied to the vibrator in the state where the angular velocity ωz about the Z-axis is acting, the Coriolis force Fx is generated in the X-axis direction. Accordingly, voltages V3 and V4 having waveforms as shown in FIG. 13 are supplied between the electrode layers E3 and F3 and between the electrode layers E4 and F4 of this sensor, and the vibration Uy in the Y-axis direction is supplied to the vibrator 130. If given, the Coriolis force Fx should be generated in the X-axis direction.

  FIG. 17 is a side sectional view showing a state in which the flexible substrate 110 is mechanically deformed by the Coriolis force Fx. If the vibrator 130 is vibrated in the Y-axis direction (direction perpendicular to the paper surface) in a state where the entire sensor rotates around the Z-axis at an angular velocity ωz, a Coriolis force Fx is generated in the X-axis direction, causing vibration. A force is applied to move the child 130 in the X-axis direction. By this force, the flexible substrate 110 is deformed as shown in the figure. Such deformation biased in the X-axis direction is not caused by the Coulomb force between the electrode layers but is caused by the Coriolis force Fx. Since the Coriolis force Fx is proportional to the angular velocity ωz, the angular velocity ωz can be detected if the value of the Coriolis force Fx can be measured.

  This Coriolis force Fx can be measured by utilizing a change in capacitance, similarly to the Coriolis force Fy. That is, the Coriolis force Fy described above can be obtained from the difference ΔC34 between the capacitance values C3 and C4, but the Coriolis force Fx can be obtained from the difference ΔC12 between the capacitance values C1 and C2 based on the same principle. .

  The procedure for detecting the angular velocity ωz around the Z axis described above is summarized as follows. First, a voltage V3 and a voltage V4 having waveforms as shown in FIG. 13 are supplied between the electrode layers E3 and F3 and between the electrode layers E4 and F4 to give the vibrator 130 a vibration Uy in the Y-axis direction. The difference ΔC12 between the capacitance values of the capacitive elements C1 and C2 is obtained. The difference ΔC12 obtained in this way is the detected value of the angular velocity ωz obtained. Since the electrode layers E3, F3, E4, and F4 used for applying vibration and the electrode layers E1, F1, E2, and F2 used for measuring the difference in capacitance value are electrically completely independent, There is no interference between the vibration mechanism and the detection mechanism.

<1.4> Coriolis Force Detection Circuit As described above, in the sensor according to the first embodiment, the angular velocity ωx around the X axis is detected by obtaining the difference ΔC34 between the capacitance values C3 and C4, and Y The angular velocity ωy around the axis is detected by obtaining the capacitance value C5, and the angular velocity ωz around the Z axis is detected by obtaining the difference ΔC12 between the capacitance values C1 and C2. Therefore, here, an example of a circuit suitable for measuring such a capacitance value or a difference between the capacitance values is disclosed.

  FIG. 18 is an example of a circuit for measuring the capacitance value of the capacitive element C. The signal applied to the input terminal T1 branches into two paths and passes through inverters 151 and 152. In the lower path, the signal passing through the inverter 152 passes through a delay circuit composed of the resistor 153 and the capacitor C, and becomes one input signal of the exclusive OR circuit 154. In the upper path, the signal passing through the inverter 151 becomes the other input signal of the exclusive OR circuit 154 as it is. The logic output of the exclusive OR circuit 154 is given to the output terminal T2. Here, the inverter 152 is an element provided for the purpose of providing a sufficient driving capability for the delay circuit constituted by the resistor 153 and the capacitive element C. The inverter 151 is an element provided for the purpose of making the upper and lower paths have the same condition, and is an element having the same operating characteristics as the inverter 152.

  In such a circuit, when an AC signal having a predetermined period is supplied to the input terminal T1, what kind of signal can be obtained at the output terminal T2 is considered. FIG. 19 is a timing chart showing waveforms appearing in the respective parts when a rectangular alternating current signal having a half period f is supplied to the input terminal T1 (actually, rounding occurs in the rectangular wave, but here, for convenience of explanation. , Shown as a pure square wave). The waveform at the node N1, which is one input terminal of the exclusive OR circuit 154, is an inverted waveform delayed by a time a necessary for passing through the inverter 151 with respect to the waveform applied to the input terminal T1. On the other hand, the waveform at the node N2, which is the other input terminal of the exclusive OR circuit 154, is the time a necessary for passing through the inverter 152 with respect to the waveform applied to the input terminal T1, the resistor 153, and the capacitive element. The inverted waveform is delayed by the total time (a + b) of the time b required to pass through the delay circuit constituted by C. As a result, the output waveform of the exclusive OR circuit 154 obtained at the output terminal T2 is a waveform having a pulse width b and a period f as shown in the figure. Here, when the capacitance value of the capacitive element C changes, the delay time b of the delay circuit constituted by the resistor 153 and the capacitive element C changes. Therefore, the obtained pulse width b is a value indicating the capacitance value of the capacitive element C.

  FIG. 20 shows an example of a circuit for measuring the difference ΔC between the capacitance values of the two capacitive elements C1 and C2. The signal applied to the input terminal T3 branches into two paths and passes through inverters 161 and 162. In the upper path, the signal passing through the inverter 161 passes through a delay circuit constituted by the resistor 163 and the capacitive element C1, and becomes one input signal of the exclusive OR circuit 165. In the lower path, the signal that has passed through the inverter 162 becomes another input signal of the exclusive OR circuit 165 through a delay circuit constituted by the resistor 164 and the capacitive element C2. The logic output of the exclusive OR circuit 165 is given to the output terminal T4. Here, the inverters 161 and 162 are elements provided for the purpose of providing sufficient drive capability for the delay circuit in the subsequent stage, and both have the same operating characteristics.

  In such a circuit, what kind of signal can be obtained at the output terminal T4 when an AC signal having a predetermined period is supplied to the input terminal T3 is considered. As shown in FIG. 21, when a rectangular AC signal is supplied to the input terminal T3, the waveform at the node N3, which is one input terminal of the exclusive OR circuit 165, becomes an inverted waveform having a predetermined delay time d1. Similarly, the waveform at the node N4 which is the other input terminal is an inverted waveform having a predetermined delay time d2. As a result, the output waveform of the exclusive OR circuit 165 obtained at the output terminal T4 is a waveform having a pulse width d as shown in the figure. Here, the pulse width d is a value corresponding to the difference between the delay times d1 and d2, and is a value corresponding to the difference ΔC between the capacitance values of the two capacitance elements C1 and C2. Thus, the capacitance value difference ΔC can be obtained as the pulse width d.

<1.5> Modification 1
In the sensor according to the first embodiment described above, the vibrator 130 is vibrated by applying a suction force based on the Coulomb force. For example, when the vibrator 130 is vibrated in the X-axis direction, as shown in FIG. 9, a first state in which charges of opposite polarity are supplied to both electrode layers E1 and F1 to apply an attractive force, As shown in FIG. 10, the second state in which charges of opposite polarity are supplied to both electrode layers E2 and F2 and the attractive force is applied may be alternately repeated. However, in order to make such vibrations more stable, it is preferable to apply a rejection force together with a suction force. For example, as shown in FIG. 22, a positive charge is supplied to the upper electrode layer E1, a negative charge is supplied to the lower electrode layer F1, and an attractive force is applied between both electrode layers. When a negative charge is supplied to both the layer E2 and the lower electrode layer F2 (a positive charge may be supplied to both) and an exclusion force is applied between the two electrode layers, the vibrator 130 moves in the positive direction of the X axis. Therefore, the operation of displacing by ΔX can be performed more stably. The state shown in FIG. 9 and the state shown in FIG. 22 are the same in that a displacement ΔX is generated in the vibrator 130, but the former depends on the force acting on one place. On the other hand, the latter depends on the force acting at two places, and the latter is more stable than the former.

  Similarly, when the vibrator 130 is displaced by −ΔX in the negative direction of the X axis as shown in FIG. 10, positive charges are applied to the upper electrode layer E2 as shown in FIG. A negative charge is supplied to each of the layers F2 to apply an attractive force between both electrode layers, and at the same time, a negative charge is supplied to both the upper electrode layer E1 and the lower electrode layer F1 (both positive charges are applied to both layers). If an exclusion force is applied between the electrode layers, the operation can be made more stable. After all, the charge of a predetermined polarity is supplied to each electrode layer at a predetermined timing so that the first state shown in FIG. 22 and the second state shown in FIG. 23 are alternately repeated. Then, the vibrator 130 can be stably vibrated in the X-axis direction. The same applies when the vibrator 130 is vibrated in the Y-axis direction.

  Next, consider a case where the vibrator 130 is vibrated in the Z-axis direction. In the embodiment described above, as shown in FIG. 11, a positive charge is supplied to the upper electrode layer E5, a negative charge is supplied to the lower electrode layer F5, and an attractive force is applied between the two electrode layers. As shown in FIG. 6, the vibration Uz is generated by alternately repeating the state of FIG. 6 and the neutral state in which no charge is supplied to any of the electrode layers. Also in this case, the operation can be further stabilized by using the exclusion force between the two electrode layers. That is, as shown in FIG. 24, a positive charge is supplied to both the upper electrode layer E5 and the lower electrode layer F5 (a negative charge may be supplied to both), and an exclusion force acts between both electrode layers. As a result, the vibrator 130 generates a displacement −ΔZ in the negative direction of the Z axis. Therefore, a charge of a predetermined polarity is supplied to each electrode layer at a predetermined timing so that the first state shown in FIG. 11 and the second state shown in FIG. 24 are alternately repeated. Then, the vibrator 130 can be stably vibrated in the Z-axis direction.

  However, although it is easy to supply charges of opposite polarity to a pair of opposing electrode layers, it is necessary to devise in order to supply charges of the same polarity. That is, a predetermined voltage may be applied between the two electrode layers in order to supply charges with opposite polarity, but such a method cannot be applied to supply charges with the same polarity. In order to solve this problem, a method of making each electrode layer into a two-layer structure via a dielectric can be used. FIG. 25 is a sectional side view of a sensor having such a structure. The lower electrode layers F <b> 1 to F <b> 5 are formed on the upper surface of the dielectric substrate 171, and auxiliary electrode layers F <b> 1 a to F <b> 5 a are formed between the dielectric substrate 171 and the flexible substrate 110. The auxiliary electrode layers F1a to F5a have the same shape as the lower electrode layers F1 to F5, respectively, and are arranged at the same positions. Similarly, the upper electrode layers E1 to E5 are formed on the lower surface of the dielectric substrate 172, and auxiliary electrode layers E1a to E5a are formed between the dielectric substrate 172 and the fixed substrate 120. The auxiliary electrode layers E1a to E5a have the same shape as the upper electrode layers E1 to E5, respectively, and are arranged at the same positions.

  With such a two-layer structure, it is possible to freely apply an attractive force between specific electrode layers and to apply an exclusion force. This is shown by a specific example. FIG. 26 is a diagram showing only the portions of each electrode layer and each dielectric substrate extracted from the sensor shown in FIG. For example, in order to apply an attractive force between the electrode layers E1 and F1, as shown in the figure, a voltage V may be applied between both electrode layers to supply charges of opposite polarity. On the other hand, when it is desired to apply a rejection force between the electrode layers E2 and F2, as shown in the figure, a voltage V may be applied between the auxiliary substrates E2a and F2a and the electrode layers E2 and F2. . Since the voltage V is applied across the dielectric substrate 171, a negative charge is generated in the electrode layer F2 and a positive charge is generated in the auxiliary electrode layer F2a. Similarly, the voltage V is applied across the dielectric substrate 172. Therefore, a negative charge is generated in the electrode layer E2, and a positive charge is generated in the auxiliary electrode layer E2a. As a result, charges having the same polarity are supplied to both the electrode layers E2 and F2, and an exclusion force can be applied between them.

<1.6> Modification 2
The first modification described above has a slightly more complicated structure than the sensor shown in FIG. On the other hand, the second modification described here is a more simplified structure of the sensor shown in FIG. That is, in the sensor of the second modification, as shown in FIG. 27, a single common electrode layer E0 is formed instead of the upper electrode layers E1 to E5. The common electrode layer E0 is a disk-shaped electrode layer having a size that faces all of the lower electrode layers F1 to F5. As described above, even if one electrode layer is formed as one common electrode layer, if the common electrode layer side is always set to the reference potential, there is no problem in the operation of the sensor. For example, when applying a voltage between specific electrode layers in order to apply vibration to the vibrator 130, the common electrode layer E0 side is grounded and a voltage is supplied to a predetermined electrode layer among the lower electrode layers F1 to F5. do it. Similarly, when detecting the Coriolis force based on the change in the capacitance value, the capacitance elements C1 to C5 may be handled with the common electrode layer E0 side as the ground.

  Thus, by replacing the five upper electrode layers E1 to E5 with a single common electrode layer E0, the mechanical structure of the sensor and the necessary wiring become simpler. Further, if the fixed substrate 120 is made of a conductive material such as a metal, the lower surface of the fixed substrate 120 can be used as the common electrode layer E0. It is not necessary to form layer E0, and the structure is further simplified.

  The above is an example in which the upper electrode layers E1 to E5 are replaced with the common electrode layer E0. Conversely, the lower electrode layers F1 to F5 can be replaced with the common electrode layer F0.

<<< Section 2 Second Example >>>
<2.1> Structure of Sensor According to Second Example Next, a multiaxial angular velocity sensor according to a second example of the present invention will be described. This second embodiment is also similar to the sensor of the first embodiment described above in that a mechanism using Coulomb force is used as the vibration mechanism and a mechanism using change in capacitance is used as the detection mechanism. is there. However, the structure is a laminate of multiple substrates, making it more suitable for mass production.

  FIG. 28 is a sectional side view of the multi-axis angular velocity sensor according to the second embodiment. The main components of this sensor are a first substrate 210, a second substrate 220, and a third substrate 230. In this embodiment, the first substrate 210 is made of a silicon substrate, the second substrate 220 and the third substrate 230 are made of a glass substrate, and the respective substrates are bonded to each other by anodic bonding. . The first substrate 210 is a substrate that plays a central role in the sensor, and FIG. 29 is a top view of the first substrate 210. As clearly shown in FIG. 29, the first substrate 210 is provided with L-shaped openings H1 to H4. Each of the openings H1 to H4 is tapered so that the width increases toward the lower surface. 29 is a side sectional view taken along the cutting line 28-28 in FIG. 29, and FIG. 30 is a side sectional view taken along the cutting line 30-30. FIG. 30 shows a tapered cross section of the openings H3 and H4. In FIG. 29, an inner square portion surrounded by four L-shaped openings H1 to H4 constitutes the vibrator 211, and an outer portion of the L-shaped openings H1 to H4 is about the vibrator 211. The support frame 213 is configured. The vibrator 211 is connected to the support frame 213 at four positions. These four connecting portions are the bridging portions 212. In other words, the square-shaped vibrator 211 is suspended by the bridging portion 212 at four locations. Moreover, as shown in FIG. 28 or FIG. 30, the bridging portion 212 is a plate-like member that is very thin compared to the original thickness of the first substrate 210 and has flexibility. For this reason, the vibrator 211 can move with a certain degree of freedom while being suspended from the bridging portion 212. On the upper surface of the vibrator 211, as shown in FIG. 29, five lower electrode layers G1 to G5 are formed. These lower electrode layers G1 to G5 have the function of generating vibration for the vibrator 211 and the Coriolis acting on the vibrator 211, like the lower electrode layers F1 to F5 in the sensor of the first embodiment described above. The function of detecting force.

  The second substrate 220 functions as a pedestal for supporting the peripheral portion of the first substrate 210. Therefore, a recess 221 is formed in a portion other than the periphery of the upper surface of the second substrate 220. By forming the recess 221, the vibrator 211 can be kept suspended without contacting the second substrate.

  The third substrate 230 functions as a lid that covers the upper surface of the first substrate 210. A bottom view of the third substrate 230 is shown in FIG. The lower surface of the third substrate 230 is cut except for a small portion around it, and an upper electrode layer G0 is formed on the cut surface 231. The upper electrode layer G0 has a square shape and faces the lower electrode layers G1 to G5 as shown in the side sectional view of FIG. 28 or FIG. The lower electrode layer G0 corresponds to the common electrode layer E0 of the sensor shown in FIG. 27 shown as the modified example 2 in the first embodiment.

  Such a sensor composed of three substrates is suitable for mass production. That is, each substrate may be separately machined (or chemically processed such as etching) to form an electrode layer and a wiring layer, and these may be joined and assembled. If a silicon substrate is used as the first substrate 210, the electrode layers G1 to G5 can be formed of a diffusion layer. The electrode layer G0 may be formed of a vapor deposition layer such as aluminum. In this way, the electrode layer and the wiring layer can be formed by a general semiconductor planar process.

<2.2> Vibration Mechanism of the Vibrator Now, a predetermined timing is provided between the five lower electrode layers G1 to G5 formed on the vibrator 211 and the upper electrode layer G0 facing the lower electrode layers G1 to G5. By supplying a voltage, a Coulomb force is applied between both electrode layers, and as a result, the vibrator 211 can be vibrated in a predetermined direction, similar to the sensor of the first embodiment described above. . However, the arrangement of the electrode layers is slightly different between the sensor of the second embodiment and the sensor of the first embodiment described above. In the sensor of the first embodiment, as shown in FIG. 7, electrode layers F1 and F2 are arranged on the X axis, and electrode layers F3 and F4 are arranged on the Y axis. On the other hand, in the sensor of the second embodiment described here, as shown in FIG. 29, none of the electrode layers G1 to G4 is arranged on the X axis or the Y axis. That is, the electrode layers G1 to G4 are arranged in the first to fourth quadrants about the XY plane, respectively. For this reason, a method of applying a voltage necessary for vibrating the vibrator 211 in a specific direction is slightly different from the above example. This will be specifically described below.

  The vibrator 211 is vibrated in the X-axis direction as follows. Here, the potential of the upper electrode layer G0 is set to the ground as a reference potential, and a predetermined voltage (for example, +5 V) is applied to the lower electrode layers G1 to G5 with respect to the reference potential. First, if a voltage of +5 V is applied to both the lower electrode layers G1 and G4, an attractive force acts between the electrode layers G1 and G0 and between the electrode layers G4 and G0. Thereby, the vibrator 211 is in a state in which the displacement ΔX is generated in the positive direction of the X axis. Next, the potentials of the lower electrode layers G1 and G4 are returned to the reference potential, and a voltage of +5 V is applied to both the lower electrode layers G2 and G3. Then, an attractive force acts between the electrode layers G2 and G0 and between the electrode layers G3 and G0. Thereby, the vibrator 211 is in a state in which the displacement −ΔX is generated in the negative direction of the X axis. If a predetermined voltage is applied to each electrode layer at a predetermined timing so that these two states are alternately repeated, the vibrator 211 can be vibrated in the X-axis direction.

  The same applies when the vibrator 211 is vibrated in the Y-axis direction. First, if a voltage of +5 V is applied to both the lower electrode layers G1 and G2, respectively, an attractive force acts between the electrode layers G1 and G0 and between the electrode layers G2 and G0. Thereby, the vibrator 211 is in a state in which the displacement ΔY is generated in the positive direction of the Y axis. Next, the potentials of the lower electrode layers G1 and G2 are returned to the reference potential, and a voltage of +5 V is applied to both the lower electrode layers G3 and G4. Then, an attractive force acts between the electrode layers G3 and G0 and between the electrode layers G4 and G0. Thereby, the vibrator 211 is in a state in which the displacement −ΔY is generated in the negative direction of the Y axis. If a predetermined voltage is applied to each electrode layer at a predetermined timing so that these two states are alternately repeated, the vibrator 211 can be vibrated in the Y-axis direction.

  Further, in order to vibrate the vibrator 211 in the Z-axis direction, the same method as that of the sensor of the first embodiment described above may be employed. That is, the operation of supplying +5 V to the lower electrode layer G5 or returning it to 0 V may be repeated.

<2.3> Coriolis Force Detection Mechanism In the sensor according to the second embodiment, the principle of detecting the Coriolis force acting on the vibrator 211 is the same as the sensor according to the first embodiment described above. It uses the change in electric capacity. However, since there is a slight difference in the arrangement of the electrode layers, there is a slight difference in the combination of capacitive elements used as detection targets. This will be specifically described below. Here, for convenience of explanation, five sets of capacitive elements constituted by combinations of the lower electrode layers G1 to G5 and the upper electrode layer G0 are referred to as capacitive elements C1 to C5, respectively, and the capacitance values of these capacitive elements are also set. Also referred to as C1 to C5.

  First, a method for detecting the Coriolis force Fx acting in the X-axis direction is examined. According to the electrode layer arrangement shown in FIG. 29, when the Coriolis force Fx in the X-axis positive direction acts on the vibrator 211, the electrode layer interval between the capacitive elements C1 and C4 is reduced, and the electrode layer interval between the capacitive elements C2 and C3. Can easily be imagined to spread. Accordingly, the capacitance values C1 and C4 increase, and the capacitance values C2 and C3 decrease. Therefore, if a difference of (C1 + C4) − (C2 + C3) is obtained, this difference becomes a value corresponding to the Coriolis force Fx.

  Next, a method for detecting the Coriolis force Fy acting in the Y-axis direction will be examined. According to the electrode layer arrangement shown in FIG. 29, when the Coriolis force Fy in the Y-axis positive direction acts on the vibrator 211, the electrode layer interval between the capacitive elements C1 and C2 is reduced, and the electrode layer interval between the capacitive elements C3 and C4. Can easily be imagined to spread. Therefore, the capacitance values C1 and C2 increase, and the capacitance values C3 and C4 decrease. Therefore, if a difference of (C1 + C2) − (C3 + C4) is obtained, this difference becomes a value corresponding to the Coriolis force Fy.

  The method for detecting the Coriolis force Fz acting in the Z-axis direction is the same as the detection method in the sensor of the first embodiment described above. That is, the capacitance value C5 of the capacitive element C5 is a value indicating the Coriolis force Fz.

  In the sensor of this embodiment, the same electrode layer is used for both the vibration mechanism and the detection mechanism at the same time. It is necessary not to interfere with the circuits to be detected.

<2.4> Modification 1
The sensor shown in FIG. 32 is a modification of the sensor according to the second embodiment shown in FIG. In this modification, in addition to the first substrate 210, the second substrate 220, and the third substrate 230, a fourth substrate 240 is further used. The fourth substrate 240 is configured by the vibrator 241 and the pedestal 242. The vibrator 241 is a block having a square shape when viewed from above, and the pedestal 242 is a frame having a shape surrounding the periphery thereof. The vibrator 241 on the fourth substrate is bonded to the vibrator 211 on the first substrate, and the vibrators 211 and 241 function as one vibrator as a whole. By adding the fourth substrate 240 in this way, the mass of the vibrator can be increased, and detection with higher sensitivity becomes possible. In this modification, five upper electrode layers G6 to G10 are provided as electrode layers facing the five lower electrode layers G1 to G5 instead of providing the common upper electrode layer G0.

<2.5> Modification 2
The sensor shown in FIG. 33 is another modification of the sensor according to the second embodiment shown in FIG. A flexible substrate 250 is a substrate that functions as the center of the sensor. FIG. 34 is a top view of the flexible substrate 250. As shown by a broken line in the figure, an annular groove is formed on the lower surface of the flexible substrate 250, and the portion where the groove is formed is flexible because it is thin ( FIG. 33 shows the flexible portion 252). Here, the inner part surrounded by the annular flexible part 252 is called an action part 251, and the outer part of the flexible part 252 is called a fixed part 253. A block-shaped vibrator 260 is fixed to the lower surface of the action portion 251. The fixing portion 253 is supported by a pedestal 270, and the pedestal 270 is fixed to the base substrate 280. After all, the vibrator 260 is suspended in the space surrounded by the base 270. Since the thin flexible portion 252 is flexible, the vibrator 260 can be displaced in this space with a certain degree of freedom. Further, a lid substrate 290 is attached to the upper portion of the flexible substrate 250 so as to cover it while ensuring a predetermined space.

  As shown in FIG. 34, five lower electrode layers F 1 to F 5 are formed on the upper surface of the flexible substrate 250. These electrode layers have the same shape and arrangement as the lower electrode layers F1 to F5 in the sensor according to the first embodiment shown in FIG. Further, a common upper electrode layer E0 is formed on the lower surface of the lid substrate 290 so as to face all of the five lower electrode layers F1 to F5. Since the operation of this sensor is the same as that of the sensor shown in FIG. 27, detailed description is omitted here.

<<< Section 3 Third Example >>>
<3.1> Structure of Sensor According to Third Example Next, a multi-axis angular velocity sensor according to a third example of the present invention will be described. The third embodiment is similar to the sensors of the first and second embodiments described above in that a mechanism using Coulomb force is used as the vibration mechanism, but the detection mechanism is a piezoresistor. It is characterized in that a mechanism using elements is used.

  FIG. 35 is a sectional side view of the multi-axis angular velocity sensor according to the third embodiment. The main components of this sensor are a first substrate 310, a second substrate 320, a third substrate 330, and a fourth substrate 340. In this embodiment, the first substrate 310 and the third substrate 330 are composed of a silicon substrate, and the second substrate 320 and the fourth substrate 340 are composed of a glass substrate. Such a structure comprising four layers of substrates is substantially the same as the modification shown in FIG. 32 in the second embodiment described above. The first substrate 310 is a substrate that plays a central role in the sensor, and FIG. 36 is a top view of the first substrate 310. As shown by a broken line in the figure, an annular groove is formed on the lower surface of the first substrate 310, and the portion where the groove is formed is flexible because it is thin. (In FIG. 35, it is shown as a flexible part 312). Here, the inner part surrounded by the annular flexible part 312 is called an action part 311, and the outer part of the flexible part 312 is called a fixed part 313. The second substrate 320 includes a block-shaped vibrator 321 and a frame-shaped base 322 surrounding the periphery. The vibrator 321 is fixed to the bottom surface of the action part 311. The pedestal 322 is fixed to the bottom surface of the fixed portion 313.

  The third substrate 330 serves as a base substrate for supporting the pedestal 322. Therefore, a recess 331 is formed in a portion other than the periphery of the upper surface of the third substrate 330. By forming the recess 331, the vibrator 321 is supported without being in contact with the third substrate 330. After all, the vibrator 321 is suspended in the space surrounded by the pedestal 322. Since the thin flexible portion 312 in the first substrate 310 has flexibility, the vibrator 321 can be displaced in this space with a certain degree of freedom. In addition, a fourth substrate 340 is attached to the upper portion of the first substrate 310 so as to cover it while securing a predetermined space.

  As shown in FIG. 36, five lower electrode layers F 1 to F 5 are formed on the upper surface of the first substrate 310. These electrode layers are equivalent to the lower electrode layers F1 to F5 in the sensor according to the first embodiment shown in FIG. However, as will be described later, a plurality of piezoresistive elements R are formed on the upper surface of the first substrate 310, and the shape of the lower electrode layers F1 to F4 avoids the formation region of these piezoresistive elements R. Therefore, the shape of the lower electrode layers F1 to F4 in the sensor shown in FIG. 6 is slightly different. Further, a common upper electrode layer E0 is formed on the lower surface of the fourth substrate 340 so as to face all of the five lower electrode layers F1 to F5.

  The piezoresistive element R is an element formed by implanting impurities into a predetermined position on the upper surface of the first substrate 310 made of silicon, and has a property that electric resistance changes due to the action of mechanical stress. As shown in FIG. 36, this piezoresistive element R has four along the X axis, four along the Y axis, and along the oblique axis with an inclination of 45 ° with respect to the Y axis. Four, a total of 12 are arranged. Both are arranged in the thin flexible portion 312, and when the bending of the flexible portion 312 occurs due to the displacement of the vibrator 321, the resistance value changes according to the bending. . In the side sectional view of FIG. 35, the illustration of these piezoresistive elements R is omitted in order to prevent the figure from becoming complicated. Here, as shown in FIG. 37, for these 12 resistive elements, the four arranged along the X axis are called Rx1, Rx2, Rx3, Rx4, and the four arranged along the Y axis. Are called Ry1, Ry2, Ry3, Ry4, and the four arranged along the oblique axis are called Rz1, Rz2, Rz3, Rz4.

<3.2> Vibrating mechanism of vibrator In this sensor, the mechanism for vibrating the vibrator 321 in a predetermined axial direction is exactly the same as the sensor according to the first embodiment shown in FIG. The five lower electrode layers F1 to F5 shown in FIG. 36 are completely equivalent to the five lower electrode layers F1 to F5 shown in FIG. 7 in terms of essential functions although there are some differences in shape. is there. Accordingly, by supplying a predetermined voltage at a predetermined timing between the five lower electrode layers F1 to F5 and the common upper electrode layer E0 opposed thereto, a Coulomb force is applied between the two electrode layers. As a result, the vibrator 321 can be vibrated in any of the X-axis, Y-axis, and Z-axis directions in the XYZ three-dimensional coordinate system.

<3.3> Coriolis Force Detection Mechanism A feature of the sensor according to the third embodiment is that Coriolis force is detected using a piezoresistive element. This detection method will be described below. Now, consider the case where the Coriolis force Fx in the positive direction of the X-axis acts on the vibrator 321 as shown in FIG. 38 (in order to avoid the figure becoming complicated, each electrode layer is not shown in this figure). ) When the Coriolis force Fx acts, the flexible portion 312 of the first substrate 310 bends as shown in the figure. Such bending changes the resistance values of the four piezoresistive elements Rx1 to Rx4 arranged along the X axis. Specifically, the resistance values of the piezoresistive elements Rx1 and Rx3 increase (indicated by “+” sign in the figure), and the resistance values of the piezoresistive elements Rx2 and Rx4 decrease (indicated by “−” sign in the figure). . Moreover, the degree of increase / decrease is proportional to the magnitude of the applied Coriolis force Fx. Further, when the Coriolis force -Fx in the negative X-axis direction is applied, the increase / decrease relationship is reversed. Accordingly, the detected Coriolis force Fx can be obtained by detecting a change in the resistance value of each piezoresistive element.

  In practice, a bridge circuit as shown in FIG. 39 is formed by the four piezoresistive elements Rx1 to Rx4, and a predetermined voltage is supplied by the power supply 350. Then, the bridge voltage Vx is measured by the voltmeter 361. Here, in a reference state where the Coriolis force does not act (the state shown in FIG. 35), if the bridge circuit is set to be balanced (the bridge voltage Vx becomes zero), it is measured by the voltmeter 361. The bridge voltage Vx indicates the Coriolis force Fx.

  On the other hand, when the Coriolis force Fy in the Y-axis direction acts, the same resistance value change occurs in the four piezoresistive elements Ry1 to Ry4 arranged along the Y-axis. Therefore, when these four piezoresistive elements form a bridge circuit as shown in FIG. 40 and a predetermined voltage is supplied by the power source 350, the bridge voltage Vy measured by the voltmeter 362 generates the Coriolis force Fy. Will show.

  Further, when the Coriolis force Fz in the Z-axis direction acts, resistance value changes occur in the four piezoresistive elements Rz1 to Rz4 arranged along the oblique axis. For example, when the Coriolis force in the positive direction of the Z-axis is applied, the resistance values of the piezoresistive elements Rz1 and Rz4 are decreased, and the resistance values of the piezoresistive elements Rz2 and Rz3 are increased. Therefore, when these four piezoresistive elements form a bridge circuit as shown in FIG. 41 and a predetermined voltage is supplied from the power supply 350, the bridge voltage Vz measured by the voltmeter 363 generates the Coriolis force Fz. Will show.

  As described above, if the Coriolis force is detected using the piezoresistive element, a mechanism for vibrating the vibrator 321 in a predetermined axial direction (using Coulomb force between the electrode layers) and a mechanism for detecting the Coriolis force. Are completely independent mechanisms, and no mutual interference occurs.

<3.4> Modified Examples The lower electrode layers F1 to F4 in the above-described sensor are arranged on the X axis and the Y axis, similarly to the sensor according to the first embodiment described above. On the other hand, like the lower electrode layers G1 to G4 in the sensor according to the second embodiment shown in FIG. 29, they can be arranged in the first quadrant to the fourth quadrant with respect to the XY plane. Further, the direction of the axis where the four piezoresistive elements Rz1 to Rz4 are arranged may be arbitrary, and may be arranged along an axis parallel to the X axis or the Y axis.

<<< Section 4 Fourth Example >>>
<4.1> Structure of Sensor According to Fourth Example Here, a multi-axis angular velocity sensor according to a fourth example of the present invention will be described. The fourth embodiment is a sensor using a mechanism using a piezoelectric element for both the vibration mechanism and the detection mechanism.

  FIG. 42 is a side sectional view of the multi-axis angular velocity sensor according to the fourth embodiment. This sensor has a structure very similar to that of the sensor according to the first embodiment shown in FIG. 6, and includes the following components. That is, basically, a piezoelectric element 430 having a disk shape is interposed between a disk-shaped flexible substrate 410 and a disk-shaped fixed substrate 420. A columnar vibrator 440 is fixed to the lower surface of the flexible substrate 410. Further, the outer peripheral portion of the flexible substrate 410 and the outer peripheral portion of the fixed substrate 420 are both supported by the sensor housing 450. Five upper electrode layers E1 to E5 (only a part of which is shown in FIG. 42) are formed on the upper surface of the piezoelectric element 430. Similarly, five lower electrode layers F1 to F1 are formed on the lower surface. F5 (only part of which is shown) is formed, the upper surfaces of the upper electrode layers E1 to E5 are fixed to the lower surface of the fixed substrate 420, and the lower surfaces of the lower electrode layers F1 to F5 are flexible substrates. It is fixed to the upper surface of 410. Here, the fixed substrate 420 has sufficient rigidity and does not bend, but the flexible substrate 410 has flexibility and functions as a so-called diaphragm. Here, for convenience of explanation, an XYZ three-dimensional coordinate system with the center of gravity O of the transducer 440 as the origin is considered. That is, an X axis is defined in the right direction of the drawing, a Z axis is defined in the upward direction, and a Y axis is defined in a direction perpendicular to the paper surface. FIG. 42 is a sectional view of the sensor cut along the XZ plane. The shapes and arrangement of the upper electrode layers E1 to E5 and the lower electrode layers F1 to F5 are exactly the same as those of the sensor of the first embodiment shown in FIG. 6 (see FIGS. 7 and 8). In this embodiment, the flexible substrate 410 and the fixed substrate 420 are both made of an insulating material. When these substrates are made of a conductive material such as metal, an insulating film may be formed between these substrates and each electrode layer so that the electrode layers are not short-circuited.

  In general, the piezoelectric element has a first property that a voltage is generated in a predetermined direction inside the piezoelectric element when a pressure is applied from the outside. Conversely, when a voltage is applied from the outside, the pressure is applied in a predetermined direction inside the piezoelectric element. A second property that occurs. These two properties are in an integrated relationship. The direction in which the pressure / voltage is generated and the direction in which the voltage / pressure is generated is specific to each piezoelectric element. Here, such a directional property is referred to as a “polarization characteristic”. I will decide. The piezoelectric element 430 used in the sensor of this embodiment is made of piezoelectric ceramics having polarization characteristics as shown in FIG. That is, from the viewpoint of the first property described above, as shown in FIG. 43 (a), when a force extending in the thickness direction is applied, a positive charge is generated on the upper electrode layer E side. When negative charges are generated on the lower electrode layer F side and a force acting in the direction of contraction in the thickness direction is applied as shown in FIG. 43 (b), the negative charges are generated on the upper electrode layer E side. The polarization characteristics are such that positive charges are respectively generated on the lower electrode layer F side. Conversely, from the viewpoint of the second property described above, as shown in FIG. 43 (a), positive charges are supplied to the upper electrode layer E side and negative charges are supplied to the lower electrode layer F side, respectively. Then, a force extending in the thickness direction is generated, and as shown in FIG. 43 (b), a negative charge is supplied to the upper electrode layer E side and a positive charge is supplied to the lower electrode layer F side. For example, it has a polarization characteristic that generates a force in the direction of shrinking in the thickness direction.

<4.2> Vibration Mechanism of Vibrator Now, what kind of phenomenon will occur when a charge having a predetermined polarity is supplied to a predetermined electrode layer of this sensor is examined. When a negative charge is supplied to the electrode layer E1 and a positive charge is supplied to F1, due to the properties shown in FIG. 43 (b), a force in the direction of shrinking in the thickness direction is generated in a part of the piezoelectric element sandwiched between both electrode layers. To do. Further, when a positive charge is supplied to the electrode layer E2 and a negative charge is supplied to F2, due to the property shown in FIG. 43 (a), a force extending in the thickness direction is applied to a part of the piezoelectric element sandwiched between both electrode layers. Will occur. As a result, the piezoelectric element 430 is deformed as shown in FIG. 44, and the vibrator 440 is displaced in the positive direction of the X axis. Here, when the polarity of the charges supplied to the electrode layers E1, F1, E2, and F2 is reversed, the expansion / contraction state of the piezoelectric element is also reversed, and the vibrator 440 is displaced in the negative direction of the X axis. If the polarity of the supplied charge is alternately reversed so that these two displacement states occur alternately, the vibrator 440 can be reciprocated in the X-axis direction. In other words, the vibration Ux in the X-axis direction can be given to the vibrator 440.

  Such charge supply can be realized by applying an AC signal between the opposing electrode layers. That is, a first AC signal is applied between the electrode layers E1 and F1, and a second AC signal is applied between the electrode layers E2 and F2. If the signals having the same frequency and the inverted phases are used as the first AC signal and the second AC signal, the vibrator 440 can be vibrated in the X-axis direction.

  The method for applying the vibration Uy in the Y-axis direction to the vibrator 440 is exactly the same. That is, the first AC signal may be applied between the electrode layers E3 and F3, and the second AC signal may be applied between the electrode layers E4 and F4.

  Next, consider a method of applying vibration Uz in the Z-axis direction to the vibrator 440. Now, when a negative charge is supplied to the electrode layer E5 and a positive charge is supplied to F5, due to the nature shown in FIG. 43 (b), a part of the piezoelectric element sandwiched between the two electrode layers has a force in the direction of shrinking in the thickness direction. Occurs. As a result, the piezoelectric element 430 is deformed as shown in FIG. 45, and the vibrator 440 is displaced in the positive direction of the Z axis. Here, when the polarity of the electric charge supplied to the electrode layers E5 and F5 is reversed, the expansion / contraction state of the piezoelectric element is also reversed, and the vibrator 440 is displaced in the Z-axis negative direction. If the polarity of the supplied charge is alternately reversed so that these two displacement states occur alternately, the vibrator 440 can be reciprocated in the Z-axis direction. In other words, the vibration Uz in the Z-axis direction can be applied to the vibrator 440. Such charge supply can be realized by applying an AC signal between the opposing electrode layers E5 and F5.

  As described above, if a predetermined alternating current signal is supplied to a specific set of electrode layers, the vibrator 430 can be vibrated along the X axis, the Y axis, and the Z axis.

<4.3> Coriolis Force Detection Mechanism Subsequently, a method for detecting Coriolis force acting in each axial direction in the sensor according to the fourth embodiment will be described. In order to save space, FIGS. 44 and 45 used in the description of the vibrator vibration method described above are also used in the description of the Coriolis force detection method.

  First, as shown in FIG. 44, consider the case where the Coriolis force Fx in the X-axis direction is applied to the vibrator 440 (according to the principle shown in FIG. Since the vibration is performed in a state in which the vibration Uy in the Y-axis direction is applied, the vibrator 440 vibrates in a direction perpendicular to the paper surface in FIG. 44. Such a vibration phenomenon in the Y-axis direction is And does not affect the measurement of the Coriolis force Fx in the X-axis direction). Due to the action of the Coriolis force Fx, the flexible substrate 410 that functions as a diaphragm is bent, and the right half of the piezoelectric element 430 is contracted in the thickness direction, and the left half is expanded in the thickness direction. Each will act. Even when the Coriolis force Fy in the Y-axis direction is applied, the same phenomenon occurs only when the axis direction is shifted by 90 °. Further, when the Coriolis force Fz in the Z-axis direction acts, as shown in FIG. 45, the piezoelectric element 430 receives a force that shrinks in the thickness direction as a whole.

  When the pressure as described above is applied to the piezoelectric element 430, charges of a predetermined polarity are generated in each electrode layer due to the property shown in FIG. Therefore, if this generated electric charge is detected, the applied Coriolis force can be detected. Specifically, the applied Coriolis forces Fx, Fy, and Fz can be detected by performing wiring as shown in FIGS. 46 to 48 for each electrode layer. For example, the Coriolis force Fx in the X-axis direction can be detected as a voltage difference Vx generated between the terminal Tx1 and the terminal Tx2, as shown in FIG. The reason for this can be easily understood by considering the polarity of the charges generated in each electrode layer due to the bending as shown in FIG. That is, with respect to the electrode layers E2 and F2, since a part of the piezoelectric element 430 sandwiched between them receives a force extending in the thickness direction, as shown in FIG. Positive charges and negative charges are generated in the lower electrode layer F2. On the other hand, with respect to the electrode layers E1 and F1, since a part of the piezoelectric element 430 sandwiched between them receives a force that shrinks in the thickness direction, as shown in FIG. 43 (b), the upper electrode layer E1 Negative charges and positive charges are generated in the lower electrode layer F1, respectively. Therefore, if wiring as shown in FIG. 46 is applied, all positive charges are collected at the terminal Tx1, all negative charges are gathered at the terminal Tx2, and the potential difference Vx between the two terminals indicates the Coriolis force Fx. Become. Exactly the same, the Coriolis force Fy in the Y-axis direction can be obtained between the terminal Ty1 and the terminal Ty2 if the upper electrode layers E3 and E4 and the lower electrode layers F3 and F4 are wired as shown in FIG. The potential difference Vy can be detected. The Coriolis force Fz in the Z-axis direction can be detected as a potential difference Vz generated between the terminal Tz1 and the terminal Tz2, as shown in FIG. The reason for this can be easily understood by considering the polarity of charges generated in each electrode layer due to the bending as shown in FIG. That is, with respect to the electrode layers E5 and F5, since a part of the piezoelectric element 430 sandwiched between them receives a force that shrinks in the thickness direction, as shown in FIG. 43 (b), the upper electrode layer E5 Negative charges and positive charges are generated in the lower electrode layer F5, respectively. Therefore, as shown in FIG. 48, if wiring is provided so that positive charges are collected at the terminal Tz1 and negative charges are collected at the terminal Tz2, the potential difference Vz between the two terminals becomes the Coriolis force Fz in the Z-axis direction. Will be shown.

<4.4> Detection of Angular Velocity The purpose of the multi-axis angular velocity sensor according to the present invention is to detect the angular velocity ω around the first axis as described in 0, and to detect the angular velocity ω around the first axis. This is to detect the Coriolis force F generated in the third axial direction at that time. As described above, in the sensor according to the fourth embodiment, by applying an AC signal between predetermined electrode layers, the vibrator 430 is moved along the X-axis, Y-axis, or Z-axis direction. The Coriolis forces Fx, Fy, Fz in the respective axial directions generated at that time can be detected as potential differences Vx, Vy, Vz, respectively. Therefore, the angular velocity ω around any of the X, Y, and Z axes can be detected based on the principle shown in FIGS.

  However, in the sensor according to this embodiment, a mechanism using a piezoelectric element is used for both the vibration mechanism and the detection mechanism. In other words, the same electrode layer may play a role of supplying charges for generating vibrations (role as a vibration mechanism), or it may play a role of detecting charges generated by Coriolis force (as a detection mechanism). May play a role. It is relatively difficult to enable the same electrode layer to play these two roles at the same time. However, in this sensor, since the following role sharing is performed for each electrode layer, two roles are not simultaneously given to the same electrode layer.

  First, let us consider the operation of detecting the angular velocity ωx around the X axis based on the principle shown in FIG. In this case, it is necessary to detect the Coriolis force Fy generated in the Y-axis direction when the vibration Uz in the Z-axis direction is applied to the vibrator. In the sensor shown in FIG. 42, in order to give the vibration Uz to the vibrator 430, an AC signal may be supplied between the electrode layers E5 and F5. Further, in order to detect the Coriolis force Fy acting on the vibrator 430, as shown in the circuit diagram of FIG. 47, the charges generated in the electrode layers E3, F3, E4, and F4 may be detected. The remaining electrode layers E1, F1, E2, and F2 are not used in this detection operation.

  Next, let us consider the operation of detecting the angular velocity ωy about the Y axis based on the principle shown in FIG. In this case, it is necessary to detect the Coriolis force Fz generated in the Z-axis direction when the vibration Ux in the X-axis direction is applied to the vibrator. In the sensor shown in FIG. 42, in order to give the vibration Ux to the vibrator 430, an AC signal whose phase is reversed may be supplied between the electrode layers E1 and F1 and between E2 and F2. Further, in order to detect the Coriolis force Fz acting on the vibrator 430, it is only necessary to detect the charges generated in the electrode layers E5 and F5, as shown in the circuit diagram of FIG. The remaining electrode layers E3, F3, E4, and F4 are not used in this detection operation.

  Finally, let us consider the operation of detecting the angular velocity ωz about the Z axis based on the principle shown in FIG. In this case, it is necessary to detect the Coriolis force Fx generated in the X-axis direction when the vibration Uy in the Y-axis direction is applied to the vibrator. In the sensor shown in FIG. 42, in order to give the vibration Uy to the vibrator 430, an AC signal whose phase is reversed may be supplied between the electrode layers E3 and F3 and between E4 and F4. Further, in order to detect the Coriolis force Fx acting on the vibrator 430, it is only necessary to detect charges generated in the electrode layers E1, F1, E2, and F2, as shown in the circuit diagram of FIG. The remaining electrode layers E5 and F5 are not used in this detection operation.

  As described above, when any one of the angular velocities ωx, ωy, and ωz is detected using this sensor, it is understood that the roles of the electrode layers are conveniently shared and the detection is performed without any trouble. However, since it is not possible to detect a plurality of angular velocities ωx, ωy, and ωz at the same time, when detecting three angular velocities, it is necessary to perform time-division processing as described later and sequentially detect them one by one. is there.

<4.5> Modification 1
According to the sensor of the fourth embodiment described above, the Coriolis forces Fx, Fy, Fz in the XYZ three-dimensional coordinate system can be obtained as potential differences Vx, Vy, Vz, respectively. The angular velocity can be detected based on these potential differences. However, in order to detect these potential differences, it is necessary to perform wiring as shown in the circuit diagrams of FIGS. 46 to 48 for each electrode layer. In this wiring, the upper electrode layer and the lower electrode layer are mixed, and when this sensor is mass-produced, the cost for wiring cannot be ignored compared with the total cost of the product. In the first modification, the polarization characteristics of the piezoelectric element are partially changed to simplify the wiring and reduce the manufacturing cost.

  In general, it is possible with current technology to produce piezoelectric elements with arbitrary polarization characteristics. For example, the piezoelectric element 430 used in the sensor according to the fourth embodiment described above has a polarization characteristic as shown in FIG. On the other hand, it is also possible to manufacture a piezoelectric element 460 having a polarization characteristic as shown in FIG. That is, as shown in FIG. 49 (a), when a force extending in the thickness direction is applied, a negative charge is applied to the upper electrode layer E side, and a positive charge is applied to the lower electrode layer F side. On the contrary, as shown in FIG. 49 (b), when a force in the direction of shrinking in the thickness direction is applied, positive charges are applied to the upper electrode layer E side and negative charges are applied to the lower electrode layer F side. Each has a polarization characteristic such that electric charges are generated. Here, for the sake of convenience, the polarization characteristics as shown in FIG. 43 will be referred to as Type I, and the polarization characteristics as shown in FIG. 49 will be referred to as Type II. In the piezoelectric element 430 having the polarization characteristic of type I and the piezoelectric element 460 having the polarization characteristic of type II, the signs of the charges generated on the upper surface and the lower surface are reversed. However, if the piezoelectric element 430 is turned upside down, the piezoelectric element 460 is obtained. Therefore, the two can be regarded as the same piezoelectric element when viewed as a single body, and there is little significance in distinguishing the two. However, a part of one piezoelectric element can have a type I polarization characteristic and another part can have a type II polarization characteristic. The modification described here is characterized in that the structure of the multi-axis angular velocity sensor is simplified by using a piezoelectric element subjected to such localized polarization processing.

  Consider a piezoelectric element 470 as shown in FIG. The piezoelectric element 470 is an element having the same disk shape as the piezoelectric element 430 used in the sensor of FIG. 42 described above. However, its polarization characteristic is different from that of the piezoelectric element 430. As described above, the piezoelectric element 430 is an element in which all portions have type I polarization characteristics. On the other hand, as shown in FIG. 50, the piezoelectric element 470 has polarization characteristics of either type I or type II in the five regions A1 to A5. That is, the regions A2 and A4 exhibit type I polarization characteristics, and the regions A1, A3 and A5 exhibit type II polarization characteristics. Here, the regions A1 to A5 correspond to regions where the upper electrode layers E1 to E5 or the lower electrode layers F1 to F5 are formed, respectively.

  In the sensor of FIG. 42, when a piezoelectric element 470 having local polarization characteristics as shown in FIG. 50 is used instead of the piezoelectric element 430, the polarity of the charge generated in each electrode layer is determined. Think about how it will change. Then, the polarity of charges generated in the upper electrode layers E 1, E 3, E 5 and the lower electrode layers F 1, F 3, F 5 formed in the region having the type II polarization characteristics is applied to the sensor using the piezoelectric element 430. It can be understood that this is reversed. For this reason, if wiring as shown in FIGS. 51 to 53 is applied to each electrode layer, the Coriolis forces Fx, Fy, and Fz can be obtained as potential differences Vx, Vy, and Vz, respectively. become. For example, with respect to the Coriolis force Fx in the X-axis direction, the polarity of charges generated in the electrode layers E1 and F1 is reversed with respect to the above example, so the wiring shown in FIG. 46 is replaced with the wiring shown in FIG. . Similarly, with respect to the Coriolis force Fy in the Y-axis direction, the polarity of charges generated in the electrode layers E3 and F3 is reversed, so that the wiring shown in FIG. 47 is replaced with the wiring shown in FIG. Further, regarding the Coriolis force Fz in the Z-axis direction, the polarity of charges generated in the electrode layers E5 and F5 is reversed, so that the wiring shown in FIG. 48 is replaced with the wiring shown in FIG.

  When the piezoelectric element 470 having local polarization characteristics is used, the polarity of the AC signal applied to vibrate the vibrator 430 must be changed as necessary. That is, when the piezoelectric element 470 having the polarization characteristic distribution shown in FIG. 50 is used, the electrode layers E1 and F1 formed in the region A1 and the electrode layers E2 and F2 formed in the region A2 If AC signals having the same phase are applied, the vibrator 430 can be vibrated in the X-axis direction. Similarly, the electrode layers E3 and F3 formed in the region A3 and the electrode layers E4 and F4 formed in the region A4. It can be understood that the vibrator 430 can be vibrated in the Y-axis direction if AC signals having the same phase are applied to the above.

  The wiring shown in FIGS. 51 to 53 has a significant merit in manufacturing an actual sensor as compared with the wiring shown in FIGS. 46 to 48. The characteristics of the wiring shown in FIGS. 51 to 53 are that the Coriolis force acts in the positive direction of each axis even when the Coriolis force in any direction of the X axis, the Y axis, and the Z axis acts. If present, the positive charge is surely generated on the upper electrode layer side and the negative charge is generated on the lower electrode layer side. If this feature is used, the wiring of the entire sensor can be simplified. For example, let us consider a case where the terminals Tx2, Ty2, and Tz2 in FIGS. 51 to 53 are connected to the sensor casing 450 to take a reference potential (ground). In this case, the five lower electrode layers F1 to F5 are in a conductive state. Even in this case, the potential difference Vx indicating the Coriolis force Fx in the X-axis direction is obtained as a voltage with respect to the ground of the terminal Tx1, and the potential difference Vy indicating the Coriolis force Fy in the Y-axis direction is obtained as a voltage with respect to the ground of the terminal Ty1. Since the potential difference Vz indicating the Coriolis force Fz in the Z-axis direction is obtained as a voltage with respect to the ground of the terminal Tz1, this sensor operates without any trouble. Moreover, the wirings for the five lower electrode layers F1 to F5 only need to be electrically connected to each other, so that a very simple wiring is sufficient.

<4.6> Modification 2
When the piezoelectric element 470 having local polarization characteristics is used as in the above-described modification example 1, wiring for connecting the five lower electrode layers F1 to F5 becomes possible. As described above, as long as the lower electrode layers F1 to F5 can be made conductive, it is not necessary to make these five electrode layers independent of each other. That is, as shown in the side sectional view of FIG. 54, only one common lower electrode layer F0 may be provided. The common lower electrode layer F0 is one disk-shaped electrode layer, and is an electrode facing all of the five upper electrode layers E1 to E5.

<4.7> Modification 3
In order to further simplify the structure of Modification 2 described above, a flexible substrate 480 made of a conductive material (for example, metal) may be used instead of the flexible substrate 410. In this way, a structure in which the lower surface of the piezoelectric element 470 is directly bonded to the upper surface of the flexible substrate 480 without using the special lower electrode layer F0 can be realized as shown in the side sectional view of FIG. . In this case, the flexible substrate 480 itself functions as the common lower electrode layer F0.

  Further, in the above-described modified examples 2 and 3, the lower electrode layer side is a common single electrode layer, but conversely, the upper electrode layer side can be a common single electrode layer.

<4.8> Other Modifications Each of the sensors described above uses a physically single piezoelectric element 430 or 470, but these may be physically constituted by a plurality of piezoelectric elements. For example, in FIG. 50, each of the regions A1 to A5 may be composed of separate and independent piezoelectric elements, and a total of five piezoelectric elements may be used. Thus, how many piezoelectric elements are physically used is a matter that can be appropriately changed in design.

  Further, in the above-described sensor, the outer peripheral portions of the flexible substrates 410 and 480 are supported by the sensor housing 450, but the flexible substrate is not necessarily fixed to the sensor housing. For example, as shown in FIG. 56, a flexible substrate 490 having a slightly smaller diameter may be used instead of the flexible substrate 480, and the periphery of the flexible substrate 490 may be left as a free end.

<<< Section 5 Fifth Example >>>
<5.1> Structure of Sensor According to Fifth Example Here, a multi-axis angular velocity sensor according to a fifth example of the present invention will be described. The fifth embodiment is also a sensor using a mechanism using a piezoelectric element for both the vibration mechanism and the detection mechanism, as in the fourth embodiment.

  FIG. 57 is a top view of the multi-axis angular velocity sensor according to the fifth embodiment. The flexible substrate 510 is a flexible disk-shaped substrate that functions as a so-called diaphragm, and a piezoelectric element 520 having a so-called donut disk shape is disposed on the flexible substrate 510. On the upper surface of the piezoelectric element 520, 16 upper electrode layers L1 to L16 each having the shape shown in the figure are formed at the positions shown in the figure. In addition, on the lower surface of the piezoelectric element 520, 16 lower electrode layers M1 to M16 (not shown in FIG. 57) having exactly the same shape as the upper electrode layers L1 to L16 are provided on the upper electrode layer. It is formed at a position facing each of L1 to L16. FIG. 58 is a side sectional view of this sensor (in order to prevent the figure from becoming complicated, only the cross-sectional cut portion is drawn for each electrode layer. The same applies to the following side sectional views). As clearly shown in this figure, the doughnut-shaped piezoelectric element 520 includes 16 upper electrode layers L1 to L16 (only L1 to L4 are shown in FIG. 58) and 16 sheets. Are sandwiched between the lower electrode layers M1 to M16 (only M1 to M4 are shown in FIG. 58) and are in a so-called sandwich state. The lower surfaces of the lower electrode layers M1 to M16 are fixed to the upper surface of the flexible substrate 510. On the other hand, the vibrator 550 is fixed to the lower surface of the flexible substrate 510, and the peripheral portion of the flexible substrate 510 is fixedly supported by the sensor housing 560. In this embodiment, the flexible substrate 510 is made of an insulating material. When the flexible substrate 510 is made of a conductive material such as metal, an insulating film is formed on the upper surface of the flexible substrate 510 to prevent the 16 lower electrode layers M1 to M16 from being short-circuited.

  Here, for convenience of explanation, an XYZ three-dimensional coordinate system with the center position O of the flexible substrate 510 as the origin is considered. That is, the X axis is defined in the right direction of FIG. 57, the Y axis in the downward direction, and the Z axis in the direction perpendicular to the paper surface. FIG. 58 is a sectional view of the sensor cut along the XZ plane. The flexible substrate 10, the piezoelectric element 20, and the electrode layers L1 to L16 and M1 to M16 are all arranged parallel to the XY plane. (In this fifth embodiment, for convenience of explanation, the downward direction in the side sectional view is the positive direction of the Z axis). As shown in FIG. 57, the W1 axis and the W2 axis are defined on the XY plane in a direction that forms an angle of 45 ° with the X axis or the Y axis. Both the W1 axis and the W2 axis pass through the origin O. When such a coordinate system is defined, the upper electrode layers L1 to L4 and the lower electrode layers M1 to M4 are arranged in order from the negative direction of the X axis toward the positive direction, and the upper electrode layers L5 to L8 and the lower electrode layers are arranged. The layers M5 to M8 are sequentially arranged from the negative direction of the Y axis toward the positive direction, and the upper electrode layers L9 to L12 and the lower electrode layers M9 to M12 are sequentially arranged from the negative direction of the W1 axis toward the positive direction. The upper electrode layers L13 to L16 and the lower electrode layers M13 to M16 are sequentially arranged from the negative direction of the W2 axis toward the positive direction.

  When an electrode layer is formed on each of the upper and lower surfaces of the piezoelectric element and a predetermined voltage is applied between the pair of electrode layers, a predetermined pressure is generated inside the piezoelectric element, and conversely, a predetermined pressure is applied to the piezoelectric element. As described above, when a force is applied, a predetermined voltage is generated between the pair of electrode layers. Therefore, 16 sets of localized elements are formed by the 16 upper electrode layers L1 to L16, the 16 lower electrode layers M1 to M16, and the 16 portions of the piezoelectric element 520 sandwiched therebetween. Assume that D1 to D16 are formed. For example, the localized element D1 is formed by the upper electrode layer L1, the lower electrode layer M1, and a part of the piezoelectric element 520 sandwiched therebetween. Eventually, 16 sets of localized elements D1 to D16 are arranged as shown in the top view of FIG.

  Here, as the piezoelectric element 520 in this sensor, a piezoelectric ceramic having polarization characteristics as shown in FIG. 60 is used. That is, as shown in FIG. 60 (a), when a force in the direction extending along the XY plane is applied, positive charges are applied to the upper electrode layer L side and negative charges are applied to the lower electrode layer M side. In contrast, as shown in FIG. 60 (b), when a force acting in the direction of contraction along the XY plane is applied, negative charges are generated on the upper electrode layer L side. It has a polarization characteristic such that positive charges are generated on the side. Here, such polarization characteristics are referred to as type III. The 16 sets of localized elements D1 to D16 in this sensor all have piezoelectric elements having type III polarization characteristics.

<5.2> Vibration Mechanism of the Vibrator Next, what kind of phenomenon occurs when a charge having a predetermined polarity is supplied to a predetermined electrode layer of the sensor will be examined. Consider a case where charges having the polarity as shown in FIG. 61 are supplied to the electrode layers constituting the four localized elements D1 to D4 arranged on the X axis. That is, positive charges are supplied to the electrode layers L1, M2, L3, and M4, and negative charges are supplied to the electrode layers M1, L2, M3, and L4, respectively. Then, the localized elements D1 and D3 extend along the XY plane due to the property shown in FIG. 60 (a). On the contrary, the localized elements D2 and D4 are shrunk along the XY plane due to the property shown in FIG. 60 (b). As a result, the flexible substrate 510 is deformed as shown in FIG. 61, and the vibrator 550 is displaced in the positive direction of the X axis. Here, when the polarity of the charge supplied to each electrode layer is reversed, the expansion and contraction state of the piezoelectric element is also reversed, and the vibrator 550 is displaced in the negative X-axis direction. If the polarity of the supplied charge is alternately reversed so that these two displacement states occur alternately, the vibrator 550 can be reciprocated in the X-axis direction. In other words, the vibration Ux in the X-axis direction can be applied to the vibrator 550.

  Such charge supply can be realized by applying an AC signal between the opposing electrode layers. That is, a first AC signal is applied between the electrode layers L1 and M1 and between the electrode layers L3 and M3, and a second AC signal is applied between the electrode layers L2 and M2 and between the electrode layers L4 and M4. If the signals having the same frequency and the inverted phases are used as the first AC signal and the second AC signal, the vibrator 550 can be vibrated in the X-axis direction.

  The method of giving the vibration Uy in the Y-axis direction to the vibrator 550 is exactly the same. That is, a first AC signal is applied between the electrode layers L5 and M5 and between the electrode layers L7 and M7, and a second AC signal is applied between the electrode layers L6 and M6 and between the electrode layers L8 and M8. If the signals having the same frequency and the inverted phases are used as the first AC signal and the second AC signal, the vibrator 550 can be vibrated in the Y-axis direction.

  Next, consider a method of applying vibration Uz in the Z-axis direction to the vibrator 550. Consider a case where charges having the polarity as shown in FIG. 62 are supplied to the electrode layers constituting the four localized elements D9 to D12 arranged on the W1 axis. That is, positive charges are supplied to the electrode layers L9, M10, M11, and L12, and negative charges are supplied to the electrode layers M9, L10, L11, and M12, respectively. Then, the localized elements D9 and D12 extend along the XY plane due to the property shown in FIG. 60 (a). On the other hand, the localized elements D10 and D11 contract along the XY plane due to the properties shown in FIG. 60 (b). As a result, the flexible substrate 510 is deformed as shown in FIG. 62, and the vibrator 550 is displaced in the positive direction of the Z axis. Here, when the polarity of the charge supplied to each electrode layer is reversed, the expansion and contraction state of the piezoelectric element is also reversed, and the vibrator 550 is displaced in the negative Z-axis direction. If the polarity of the supplied charge is alternately reversed so that these two displacement states occur alternately, the vibrator 550 can be reciprocated in the Z-axis direction. In other words, the vibration Uz in the Z-axis direction can be applied to the vibrator 550.

  Such charge supply can also be realized by applying an AC signal between opposing electrode layers. That is, a first AC signal is applied between the electrode layers L9 and M9 and between the electrode layers L12 and M12, and a second AC signal is applied between the electrode layers L10 and M10 and between the electrode layers L11 and M11. If the signals having the same frequency and the inverted phases are used as the first AC signal and the second AC signal, the vibrator 550 can be vibrated in the Z-axis direction.

  As shown in FIG. 59, the sensor is further provided with four localized elements D13 to D16 along the W2 axis. These four localized elements are not necessarily required. In this embodiment, the four localized elements are provided for the purpose of further stabilizing the vibration operation in the Z-axis direction and increasing the detection accuracy of the Coriolis force Fz in the Z-axis direction, which will be described later. It is. The four localized elements D13 to D16 perform the same function as the above-described four localized elements D9 to D12. That is, if the same AC signal as that supplied to the localized elements D9 to D12 is supplied to the localized elements D13 to D16, the vibration operation in the Z-axis direction can be performed by the eight localized elements D9 to D16. As a result, more stable vibration operation becomes possible.

  As described above, if a predetermined AC signal is supplied to a specific localized element, the vibrator 550 can be vibrated along the X axis, the Y axis, and the Z axis.

<5.3> Coriolis Force Detection Mechanism Next, a method for detecting Coriolis force acting in each axial direction in the sensor according to the fifth embodiment will be described. In order to save space, FIG. 61 and FIG. 62 used in the description of the vibrator vibration method described above are also used in the description of the Coriolis force detection method.

  First, as shown in FIG. 61, consider the case where the Coriolis force Fx in the X-axis direction acts on the center of gravity G of the vibrator 550 (according to the principle shown in FIG. Since the measurement is performed in a state in which the vibration Uy in the Y-axis direction is given, the vibrator 550 vibrates in a direction perpendicular to the paper surface in FIG. 61. The vibration phenomenon does not affect the measurement of the Coriolis force Fx in the X-axis direction). Due to the action of the Coriolis force Fx, the flexible substrate 510 that functions as a diaphragm bends and deforms as shown in FIG. As a result, the localized elements D1 and D3 arranged along the X axis extend in the X axis direction, and the localized elements D2 and D4 arranged along the X axis contract in the X axis direction. Since the piezoelectric elements sandwiched between these electrode layers have polarization characteristics as shown in FIG. 60, these electrode layers are indicated by symbols “+” or “−” enclosed in small circles in FIG. Charges of the polarity shown are generated. Further, when the Coriolis force Fy in the Y-axis direction is applied, charges having a predetermined polarity are generated in the same manner for the electrode layers constituting the localized elements D5 to D8 arranged along the Y-axis.

  Next, consider a case where the Coriolis force Fz in the Z-axis direction is applied. In this case, the flexible substrate 510 functioning as a diaphragm is deformed as shown in FIG. 62, and the localized elements D9 and D12 arranged along the W1 axis extend in the W1 axis direction and also along the W1 axis. Thus, the localized elements D10 and D11 are contracted in the W1 axis direction. For this reason, charges having polarities as indicated by symbols “+” or “−” surrounded by small circles in FIG. 62 are generated in the electrode layers constituting the localized elements D9 to D12. Similarly, charges having a predetermined polarity are also generated in the respective electrode layers constituting the localized elements D13 to D16 arranged along the W2 axis.

  If such a phenomenon is utilized, the Coriolis forces Fx, Fy, and Fz can be detected by providing wirings as shown in FIGS. 63 to 65 to the respective electrode layers. For example, the Coriolis force Fy in the X-axis direction can be detected as a voltage difference Vx generated between the terminal Tx1 and the terminal Tx2, as shown in FIG. The reason for this can be easily understood by considering the polarity of charges generated in each electrode layer due to the bending as shown in FIG. If wiring as shown in FIG. 63 is applied, all positive charges are collected at the terminal Tx1, all negative charges are gathered at the terminal Tx2, and the potential difference Vx between the two terminals indicates the Coriolis force Fx in the X-axis direction. become. Exactly the same, the Coriolis force Fy in the Y-axis direction can be obtained between the terminal Ty1 and the terminal Ty2 if wiring as shown in FIG. 64 is applied to each electrode layer constituting the localized elements D5 to D8. It can be detected as a potential difference Vy. Further, the Coriolis force Fz in the Z-axis direction is a voltage generated between the terminal Tz1 and the terminal Tz2 if wiring as shown in FIG. 65 is applied to each electrode layer constituting the localized elements D9 to D16. It can be detected as a difference Vz. However, the localized elements D13 to D16 are not necessarily required, and the Coriolis force Fz in the Z-axis direction can be detected even if only four localized elements D9 to D12 are used.

<5.4> Detection of Angular Velocity As described above, in the multi-axis angular velocity sensor according to the fifth embodiment, by applying an AC signal to a predetermined local element, the vibrator 550 is made to have the X axis and Y axis. The Coriolis forces Fx, Fy, Fz in each axial direction generated at that time can be detected as potential differences Vx, Vy, Vz, respectively. . Therefore, the angular velocity ω around any of the X, Y, and Z axes can be detected based on the principle shown in FIGS.

  However, in the sensor according to the fifth embodiment, similarly to the sensor according to the fourth embodiment described above, a mechanism using a piezoelectric element (local element) is used for both the vibration mechanism and the detection mechanism. Yes. Therefore, the role sharing of each localized element in the detection operation of each angular velocity is examined.

  First, let us consider the operation of detecting the angular velocity ωx around the X axis based on the principle shown in FIG. In this case, it is necessary to detect the Coriolis force Fy generated in the Y-axis direction when the vibration Uz in the Z-axis direction is applied to the vibrator. In order to give the vibration Uz to the vibrator 550, an AC signal may be supplied to the localized elements D9 to D16 arranged on the W1 axis and the W2 axis. Further, in order to detect the Coriolis force Fy acting on the vibrator 550, the voltage generated in the localized elements D5 to D8 arranged on the Y axis may be detected. The remaining localized elements D1 to D4 are not used in this detection operation.

  Next, let us consider the operation of detecting the angular velocity ωy about the Y axis based on the principle shown in FIG. In this case, it is necessary to detect the Coriolis force Fz generated in the Z-axis direction when the vibration Ux in the X-axis direction is applied to the vibrator. In order to give the vibration Ux to the vibrator 550, an AC signal may be supplied to the localized elements D1 to D4 arranged on the X axis. Further, in order to detect the Coriolis force Fz acting on the vibrator 550, the voltage generated in the localized elements D9 to D16 arranged on the W1 axis and the W2 axis may be detected. The remaining localized elements D5 to D8 are not used in this detection operation.

  Finally, let us consider the operation of detecting the angular velocity ωz about the Z axis based on the principle shown in FIG. In this case, it is necessary to detect the Coriolis force Fx generated in the X-axis direction when the vibration Uy in the Y-axis direction is applied to the vibrator. In order to apply the vibration Uy to the vibrator 550, an AC signal may be supplied to the localized elements D5 to D8 arranged on the Y axis. Further, in order to detect the Coriolis force Fx acting on the vibrator 550, the voltage generated in the localized elements D1 to D4 arranged on the X axis may be detected. The remaining localized elements D9 to D16 are not used in this detection operation.

  As described above, when any one of the angular velocities ωx, ωy, and ωz is detected using this sensor, it is understood that the role sharing for each localized element is conveniently performed and the detection is performed without any trouble. However, since it is not possible to detect a plurality of angular velocities ωx, ωy, and ωz at the same time, when detecting three angular velocities, it is necessary to perform time-division processing as described later and sequentially detect them one by one. is there.

<5.5> Modification 1
According to the sensor according to the fifth embodiment described above, the Coriolis forces Fx, Fy, Fz in the XYZ three-dimensional coordinate system can be obtained as potential differences Vx, Vy, Vz, respectively. The angular velocity can be detected based on these potential differences. However, in order to detect these potential differences, it is necessary to perform wiring as shown in the circuit diagrams of FIGS. 63 to 65 for each electrode layer. In this wiring, the upper electrode layer and the lower electrode layer are mixed, and when this sensor is mass-produced, the cost for wiring cannot be ignored compared with the total cost of the product. In the first modification, the polarization characteristics of the piezoelectric element are partially changed to simplify the wiring and reduce the manufacturing cost.

  As already mentioned, it is possible with the current technology to manufacture piezoelectric elements with arbitrary polarization characteristics. For example, the piezoelectric element 520 used in the sensor according to the fifth embodiment described above has a type III polarization characteristic as shown in FIG. On the other hand, it is also possible to manufacture a piezoelectric element 530 having a type IV polarization characteristic as shown in FIG. That is, as shown in FIG. 66 (a), when a force in the direction extending along the XY plane is applied, negative charges are applied to the upper electrode layer L side and positive charges are applied to the lower electrode layer M side. In contrast, as shown in FIG. 66 (b), when a force acting in the direction of contraction along the XY plane is applied, positive charges are generated on the upper electrode layer L side, and the lower electrode layer M It is possible to manufacture a piezoelectric element 530 having a polarization characteristic such that negative charges are generated on the side. It is also possible to have a type III polarization characteristic in one piezoelectric element and a type IV polarization characteristic in another part. The modification described here simplifies the structure of the sensor by using a piezoelectric element subjected to such localized polarization processing.

  Consider a piezoelectric element 540 as shown in FIG. The piezoelectric element 540 is an element having a donut disk shape that is exactly the same as the piezoelectric element 520 used in the sensor of FIG. 57 described above. However, its polarization characteristic is different from that of the piezoelectric element 520. As described above, the piezoelectric element 520 is an element in which all portions have type III polarization characteristics. On the other hand, as shown in FIG. 67, the piezoelectric element 540 has polarization characteristics of either type III or type IV in each of the 16 regions. In other words, the region of the localized elements D1, D3, D5, D7, D9, D12, D13, D16 exhibits type III polarization characteristics, and the localized elements D2, D4, D6, D8, D10, D11, D14, D15. This region shows type IV polarization characteristics (see FIGS. 59 and 67).

  If the piezoelectric element 540 having the polarization characteristics shown in FIG. 67 is used instead of the piezoelectric element 520 in the sensor shown in FIG. 57, what is the polarity of the charge generated in each electrode layer? Is considered, the upper electrode layers L2, L4, L6, L8, L10, L11, L14, L15 and the lower electrode layers M2, M4, which are formed in a region having type IV polarization characteristics, are considered. It can be seen that the polarity of charges generated in M6, M8, M10, M11, M14, and M15 is reversed. For example, when the Coriolis force Fx in the X-axis direction is applied, the above-described sensor of FIG. 57 generates charges having the polarities as shown in FIG. 61, whereas the sensor of this modification example is shown in FIG. Such a charge is generated. Further, when the Coriolis force Fz in the Z-axis direction is applied, the above-described sensor of FIG. 57 generates charges having the polarities as shown in FIG. 62, whereas the sensor of this modification example is shown in FIG. Such a charge is generated. Therefore, if wiring as shown in FIGS. 70 to 72 is applied to each electrode layer, the Coriolis forces Fx, Fy, and Fz can be obtained as potential differences Vx, Vy, and Vz, respectively. become.

  For example, regarding the detection operation of the Coriolis force Fx in the X-axis direction, the polarity of charges generated in the electrode layers L2, M2 and L4, M4 is reversed, so the wiring shown in FIG. 63 is replaced with the wiring shown in FIG. It is done. Similarly, regarding the detection operation of the Coriolis force Fy in the Y-axis direction, the polarity of charges generated in the electrode layers L6, M6 and L8, M8 is reversed, so that the wiring shown in FIG. 64 is replaced with the wiring shown in FIG. Replaced. Further, regarding the detection operation of the Coriolis force Fz in the Z-axis direction, since the polarities of the charges generated in the electrode layers L10, M10, L11, M11, L14, M14, and L15, M15 are reversed, the wiring shown in FIG. Is replaced with the wiring shown in FIG.

  Note that, when the piezoelectric element 540 having local polarization characteristics is used, the AC signal applied to vibrate the vibrator 550 is also simplified. That is, when vibrating in the X-axis direction, as shown in FIG. 68, an in-phase AC signal may be supplied to all of the localized elements D1 to D4. Similarly, when vibrating in the Y-axis direction. May supply an in-phase AC signal to all of the localized elements D5 to D8. Further, in the case of vibrating in the Z-axis direction, an in-phase AC signal may be supplied to all of the localized elements D9 to D16, as shown in FIG.

  The wiring shown in FIGS. 70 to 72 has a significant merit in manufacturing an actual sensor as compared to the wiring shown in FIGS. 63 to 65. The features of the wiring shown in FIGS. 70 to 72 are that the Coriolis force acts in the positive direction of each axis even when the Coriolis force acts in any of the X-axis, Y-axis, and Z-axis directions. If present, the positive charge is surely generated on the upper electrode layer side and the negative charge is generated on the lower electrode layer side. If this feature is used, the wiring of the entire sensor can be simplified. For example, let us consider a case where the terminals Tx2, Ty2, and Tz2 in FIGS. 70 to 72 are connected to the sensor housing 560 to take a reference potential (ground). In this case, the 16 lower electrode layers M1 to M16 are in a conductive state. Even in this case, the potential difference Vx indicating the Coriolis force Fx in the X-axis direction is obtained as a voltage with respect to the ground of the terminal Tx1, and the potential difference Vy indicating the Coriolis force Fy in the Y-axis direction is obtained as a voltage with respect to the ground of the terminal Ty1. Since the potential difference Vz indicating the Coriolis force Fz in the Z-axis direction is obtained as a voltage with respect to the ground of the terminal Tz1, this sensor operates without any trouble. In addition, the wirings for the 16 lower electrode layers M1 to M16 need only be electrically connected to each other, so that very simple wiring is sufficient.

<5.6> Modification 2
When the piezoelectric element 540 having local polarization characteristics is used as in Modification 1 described above, wiring for connecting the 16 lower electrode layers M1 to M16 becomes possible. As described above, as long as the lower electrode layers M1 to M16 can be made conductive, it is not necessary to make these 16 electrode layers independent of each other. That is, as shown in the side sectional view of FIG. 73, only one common lower electrode layer M0 may be provided. The common lower electrode layer M0 is one donut-like electrode layer, and is an electrode facing all of the 16 upper electrode layers L1 to L16.

<5.7> Modification 3
In order to further simplify the structure of Modification 2 described above, a flexible substrate 570 made of a conductive material (for example, metal) may be used instead of the flexible substrate 510. In this way, a structure in which the lower surface of the piezoelectric element 540 is directly bonded to the upper surface of the flexible substrate 570 without using a special lower electrode layer M0 can be realized as shown in the side sectional view of FIG. . In this case, the flexible substrate 570 itself functions as the common lower electrode layer M0.

  Further, in the above-described modified examples 2 and 3, the lower electrode layer side is a common single electrode layer, but conversely, the upper electrode layer side can be a common single electrode layer.

<5.8> Other Modifications All of the sensors described above use a physically single piezoelectric element 520 or 540, but these may be physically configured by a plurality of piezoelectric elements. For example, in FIG. 59, each of the localized elements D1 to D16 may be configured using separate and independent piezoelectric elements, and a total of 16 piezoelectric elements may be used. In addition, one localized element is used for two localized elements, for example, a single piezoelectric element is used for the localized elements D1 and D2, and another piezoelectric element is used for the localized elements D3 and D4. A total of eight piezoelectric elements can be used. Thus, how many piezoelectric elements are physically used is a matter that can be appropriately changed in design.

<<< Section 6 Sixth Example >>>
<6.1> Principle of Sensor According to Sixth Example A multi-axis angular velocity sensor according to a sixth example described here uses a mechanism using electromagnetic force as a vibration mechanism and a differential transformer as a detection mechanism. It is a sensor using the mechanism used. First, the principle will be briefly described with reference to FIG. Now, the origin O is set at the position of the center of gravity of the vibrator 610 made of a magnetic material, and an XYZ three-dimensional coordinate system is defined. A pair of coils J1 and J2 are provided on the X axis, a pair of coils J3 and J4 are provided on the Y axis, and a pair of coils J5 and J6 are provided on the Z axis so as to sandwich the vibrator 610.

  By arranging six coils in this way, the vibrator 610 made of a magnetic material can be vibrated in any axial direction of the X axis, the Y axis, and the Z axis. For example, in order to apply the vibration Ux in the X-axis direction, the coils J1 and J2 arranged on the X-axis may be energized alternately. When the coil J1 is energized, the vibrator 610 moves in the X-axis positive direction by the magnetic force generated by the coil J1, and when the coil J2 is energized, the vibrator 610 is moved by the magnetic force generated by the coil J2. Move in the negative direction. Therefore, when energization is performed alternately, the vibrator 610 reciprocates in the X-axis direction. Similarly, in order to give the vibration Uy in the Y-axis direction, the coils J3 and J4 arranged on the Y-axis need only be energized. In order to give the vibration Uz in the Z-axis direction, What is necessary is just to supply with electricity to the arranged coils J5 and J6 alternately.

  On the other hand, the displacement of the vibrator 610 made of a magnetic material can be detected by the six coils arranged in this manner. For example, when the vibrator 610 is displaced in the positive direction of the X axis, the distance between the vibrator 610 and the coil J1 approaches, and the distance between the vibrator 610 and the coil J2 increases. Generally, when a change occurs in the distance of the magnetic material to the coil, a change occurs in the inductance of the coil. Therefore, if the inductance change of the coil J1 and the inductance change of the coil J2 are detected, the displacement of the vibrator 610 in the X-axis direction can be recognized. Similarly, the displacement in the Y-axis direction of the vibrator 610 can be recognized by the inductance change of the coil J3 and the inductance change of the coil J4, and the vibration is generated by the inductance change of the coil J5 and the inductance change of the coil J6. The displacement of the child 610 in the Z-axis direction can be recognized. Therefore, if the vibrator 610 is displaced by the Coriolis force, the Coriolis force in each axial direction can be detected by the inductance change of each coil.

  As described above, the coils J1 to J6 serve both to vibrate the vibrator 610 and to detect the displacement of the vibrator 610. However, the vibration coil and the detection coil may be provided separately. Good.

<6.2> Specific sensor structure and operation FIG. 76 is a side sectional view showing a specific structure of a multi-axis angular velocity sensor based on the above-described principle. A columnar vibrator 610 made of a magnetic material such as iron is housed in a sensor housing 620. A partition plate 630 is joined to the upper surface of the sensor housing 620, and a dish-like diaphragm 640 is attached to the upper surface of the partition plate 630 so as to face down. The upper end of the connecting rod 650 is fixed to the center of the diaphragm. A through hole is formed at the center of the partition plate 630, and the connecting rod 650 is inserted through the through hole. A vibrator 610 is attached to the lower end of the connecting rod 650, and the vibrator 610 is suspended in the sensor housing 620 by the connecting rod 650. A protective cover 660 is attached above the partition plate 630 so as to cover the diaphragm 640.

  Here, the origin O is set at the position of the center of gravity of the vibrator 610, the Y axis is set to the right in FIG. 76, the Z axis is set upward, and the X axis is set in the direction perpendicular to the paper surface. Then, six coils J1 to J6 are arranged inside the sensor housing 620 as shown in the figure (the coils J1 and J2 are not shown in FIG. 76, but the coil J1 is disposed on the front side of the vibrator 610). However, the coil J2 is disposed on the other side). This arrangement is the same as that shown in FIG.

  As described above, by energizing a predetermined coil, the vibrator 610 can be vibrated in a predetermined axial direction, and by detecting a change in inductance of the predetermined coil, the vibrator 610 can be operated in a predetermined axial direction. Coriolis force can be detected. Therefore, it becomes possible to detect an angular velocity around a predetermined axis based on the basic principle shown in FIGS.

<<< Section 7 Detection Operation >>>
<7.1> Detection of Acceleration Each of the various embodiments described above is a multi-axis angular velocity sensor, but in fact, these sensors also have a function as a multi-axis acceleration sensor. This will be shown for the sensor of the first embodiment. FIG. 15 is a diagram for explaining the operation of detecting the angular velocity ωx about the X axis in the sensor of the first embodiment. In order to detect the angular velocity ωx, the Coriolis force Fy acting in the Y-axis direction may be measured in a state where the vibration Uz in the Z-axis direction is applied to the vibrator 130. The reason why the Coriolis force Fy in the Y-axis direction is generated is that the vibrator 130 is intentionally vibrated in the Z-axis direction in a state where the angular velocity ωx is applied. If the vibrator 130 is not vibrated, the Coriolis force Fy is not generated. However, there is a case where a force Fy that tries to move the vibrator 130 in the Y-axis direction is generated even though the vibrator 130 is not vibrated. This is a case where acceleration in the Y-axis direction acts on the vibrator 130. According to the basic law of mechanics, when acceleration acts on an object with mass, a force proportional to the mass of the object acts in the same direction as the acceleration. Therefore, when acceleration in the Y-axis direction acts on the vibrator 130, a force Fy in the Y-axis direction having a magnitude proportional to the mass of the vibrator 130 acts. Thus, the force Fy caused by acceleration and the Coriolis force Fy are exactly the same as the force, and the force caused by the acceleration can be detected by the same method as the Coriolis force detection method.

  After all, in the sensor of each embodiment described above, the force detected in the predetermined axial direction in a state where the vibrator is intentionally vibrated in the predetermined axial direction is the Coriolis force, and the magnitude of this Coriolis force is The value corresponds to the angular velocity around a predetermined axis. However, the force detected in the predetermined axial direction without vibrating the vibrator is a force based on the acceleration acting in the axial direction, and the magnitude of this force is a value corresponding to the acceleration in the axial direction. It becomes. As described above, the sensor of each of the embodiments described above functions as an angular velocity sensor if measurement is performed with the vibrator being vibrated, but functions as an acceleration sensor if measurement is performed without vibrating the vibrator. Become.

<7.2> Time-division detection operation As described above, the sensor according to the present invention has both a function as a multi-axis angular velocity sensor and a function as a multi-axis acceleration sensor. Therefore, in practice, by performing a time division detection operation as shown in the flowchart of FIG. 77, the acceleration αx in the X-axis direction, the acceleration αy in the Y-axis direction, the acceleration αz in the Z-axis direction, and the angular velocity around the X-axis. Six components, ωx, angular velocity ωy around the Y axis, and angular velocity ωz around the Z axis, can be detected.

  First, in step S1, the accelerations αx, αy, αz in the respective axial directions are simultaneously detected. That is, the detection process equivalent to the detection of the Coriolis force may be performed without vibrating the vibrator. The force detected at this time is not actually a Coriolis force but a force generated based on acceleration. As for acceleration, it is possible to detect three-axis components simultaneously. This is because it is not necessary to perform an operation of applying vibration to the vibrator, and each electrode layer does not need to play a role as a vibration mechanism, and only needs to play a role as a detection mechanism. For example, in the case of the sensor according to the fourth embodiment shown in FIG. 42, circuits as shown in FIGS. 46 to 48 are formed to detect the Coriolis force. In the case of detecting acceleration, it is not necessary to supply an AC signal for applying vibration, so an AC signal is applied to any of the electrode layers E1 to E5 and F1 to F5 shown in these circuits. There is no need. Accordingly, the potential differences Vx, Vy, Vz detected by these circuits indicate the accelerations αx, αy, αz as they are.

  Subsequently, angular velocity ωx is detected in step S2, angular velocity ωy is detected in next step S3, and angular velocity ωz is detected in subsequent step S4. Regarding the angular velocity, as already described, the angular velocities around the three axes cannot be detected simultaneously. Accordingly, the angular velocities are sequentially detected by such time division.

  Finally, as long as the process returns from step S5 to step S1 again and the detection operation is continuously executed, the same operation is repeatedly executed.

<7.3> Detection Circuit Next, FIG. 78 shows a basic configuration of a detection circuit for performing the time division detection operation as described above. Here, the block 700 corresponds to various embodiments of the multi-axis angular velocity sensor described so far, and is divided into two parts of a vibration part 710 and a detection part 720 from the viewpoint of function. is there. The vibration unit 710 is a part having a function of vibrating a built-in vibrator in a predetermined axial direction. When a drive signal is supplied to each terminal indicated by X, Y, and Z in the drawing, each vibrator has an X axis. Vibrates in the Y-axis and Z-axis directions. The detection unit 720 is a part having a function of outputting a detection signal indicating the displacement of the built-in vibrator. The X, Y, and Z axes are respectively connected to terminals indicated by X, Y, and Z in the drawing. A displacement detection signal in the axial direction is output. In an actual sensor, one electrode layer may serve both as a function on the vibration unit 710 side and a function on the detection unit 720 side, and each of the parts constituting the sensor is either the vibration unit 710 or the detection unit 720. However, for the sake of convenience, it will be expressed by a simple model such as block 700 by taking this sensor functionally.

  The vibration generation circuit 711 is a circuit that generates a drive signal to be supplied to each of the terminals X, Y, and Z of the vibration unit 710. Specifically, the vibration generation circuit 711 is a device that generates an AC signal, for example. The multiplexer 712 includes switches SW1, SW2, and SW3, and controls which terminal X, Y, and Z of the vibration unit 710 the drive signal generated by the vibration generation circuit 711 is supplied to. On the other hand, detection signals output from the terminals X, Y, and Z of the detection unit 720 are supplied to the displacement detection circuit 721 via the multiplexer 722. The multiplexer 722 includes switches SW4, SW5, and SW6, and selects a detection signal to be given to the displacement detection circuit 721. The displacement detection circuit 721 detects a specific amount of displacement based on the given detection signal, and supplies this to the detection value output circuit 730. The controller 740 controls the operations of the multiplexers 712 and 722 and supplies a control signal to the detection value output circuit 730.

  The above is the configuration of this detection circuit. Note that FIG. 78 is not a specific circuit diagram showing an actual current path, but a diagram showing an outline of the configuration of the detection circuit. Therefore, one line shown in the figure indicates a path of a group of control signals or detection signals, and does not indicate the current path itself. For example, only one control signal line is drawn between the switch SW1 and the terminal X of the vibration unit 710. In practice, however, in order to vibrate the vibrator in the X-axis direction, a plurality of control signal lines are used. An AC signal having a predetermined phase needs to be supplied to the electrode layer, and a plurality of current paths are required.

  If such a detection circuit is configured, the detection operation shown in the flowchart of FIG. 77 is executed as follows. First, the controller 740 performs processing of detecting accelerations αx, αy, αz as step S1. That is, the controller 740 gives instructions to the multiplexers 712 and 722 to turn off the switches SW1, SW2, and SW3 and turn on all of the switches SW4, SW5, and SW6. As a result, no drive signal is supplied to the vibration unit 710 and no intentional excitation is performed on the vibrator. Therefore, at this time, the detection signals output from the respective terminals X, Y, and Z of the detection unit 720 are signals indicating displacement generated by force based on the action of acceleration, not Coriolis force. Since all of the switches SW4, SW5, and SW6 are ON, all three signals are supplied to the displacement detection circuit 721, and here, the displacement amounts in the X, Y, and Z directions are detected. The controller 740 instructs the detection value output circuit 730 to output the three detected displacement amounts as acceleration values. Thus, the displacement amounts in the three-axis directions detected by the displacement detection circuit 721 are output from the detection value output circuit 730 as acceleration values αx, αy, αz, respectively.

Subsequently, the controller 740 performs a process of detecting the angular velocity ωx as step S2. That is, the controller 740 is based on the principle shown in FIG.
Switch SW1: OFF Switch SW4: OFF
Switch SW2: OFF Switch SW5: ON
Switch SW3: ON Switch SW6: OFF
Is given to the multiplexers 712 and 722. As a result, the vibration unit 710 applies a vibration Uz in the Z-axis direction to the vibrator, and the detection unit 720 outputs a detection signal indicating the displacement of the vibrator in the Y-axis direction due to the action of the Coriolis force Fy generated at this time from the terminal Y. To do. The displacement detection circuit 721 detects the amount of displacement in the Y-axis direction based on this detection signal. The controller 740 instructs the detection value output circuit 730 to output the detected displacement amount as the value of the angular velocity ωx around the X axis. Thus, the displacement amount in the Y-axis direction detected by the displacement detection circuit 721 is output from the detection value output circuit 730 as an angular velocity ωx.

Next, the controller 740 performs a process of detecting the angular velocity ωy as step S3. That is, the controller 740 is based on the principle shown in FIG.
Switch SW1: ON Switch SW4: ON
Switch SW2: OFF Switch SW5: OFF
Switch SW3: OFF Switch SW6: OFF
Is given to the multiplexers 712 and 722. As a result, the vibration unit 710 applies a vibration Ux in the X-axis direction to the vibrator, and the detection unit 720 outputs a detection signal indicating the displacement of the vibrator in the Z-axis direction due to the action of the Coriolis force Fz generated at this time from the terminal Z. To do. The displacement detection circuit 721 detects the amount of displacement in the Z-axis direction based on this detection signal. The controller 740 instructs the detection value output circuit 730 to output the detected displacement as the value of the angular velocity ωy about the Y axis. Thus, the displacement amount in the Z-axis direction detected by the displacement detection circuit 721 is output from the detection value output circuit 730 as an angular velocity ωy.

Furthermore, the controller 740 performs a process of detecting the angular velocity ωz as step S4. That is, the controller 740 is based on the principle shown in FIG.
Switch SW1: OFF Switch SW4: OFF
Switch SW2: ON Switch SW5: OFF
Switch SW3: OFF Switch SW6: ON
Is given to the multiplexers 712 and 722. As a result, the vibration unit 710 applies vibration Uy in the Y-axis direction to the vibrator, and the detection unit 720 outputs a detection signal indicating the displacement of the vibrator in the X-axis direction due to the action of the Coriolis force Fx generated at this time from the terminal X. To do. The displacement detection circuit 721 detects the amount of displacement in the X-axis direction based on this detection signal. The controller 740 instructs the detection value output circuit 730 to output the detected displacement as the value of the angular velocity ωz about the Z axis. Thus, the displacement amount in the X-axis direction detected by the displacement detection circuit 721 is output from the detection value output circuit 730 as an angular velocity ωz.

  The above processing is repeatedly executed through step S5. Therefore, if this sensor is mounted on a moving object, it is possible to continuously detect the acceleration in the three-axis direction and the angular velocity around the three axes at each time point.

<7.4> Another Detection Principle of Angular Velocity All of the explanations so far relating to the detection of multiaxial angular velocities were based on the basic principle shown in FIGS. On the other hand, detection based on the basic principle shown in FIGS. 79 to 81 is also possible. For example, when the angular velocity ωx around the X axis is detected, according to the basic principle shown in FIG. 3, the Coriolis force Fy generated in the Y axis direction when the vibration Uz in the Z axis direction is applied to the vibrator is detected. However, according to the basic principle shown in FIG. 79, the Coriolis force Fz generated in the Z-axis direction when the vibration Uy in the Y-axis direction is applied to the vibrator may be detected. Similarly, when detecting the angular velocity ωy about the Y-axis, according to the basic principle shown in FIG. 4, the Coriolis force Fz generated in the Z-axis direction when the vibration Ux in the X-axis direction is applied to the vibrator is detected. However, according to the basic principle shown in FIG. 80, the Coriolis force Fx generated in the X-axis direction when the vibration Uz in the Z-axis direction is applied to the vibrator may be detected. When detecting the angular velocity ωz about the Z axis, according to the basic principle shown in FIG. 5, the Coriolis force Fx generated in the X axis direction when the vibration Uy in the Y axis direction is applied to the vibrator is detected. However, according to the basic principle shown in FIG. 81, the Coriolis force Fy generated in the Y-axis direction when the vibration Ux in the X-axis direction is applied to the vibrator may be detected.

  In short, the multi-axis angular velocity sensor according to the present invention has a vibration U in the second axial direction when an angular velocity ω is acting around the first axis with respect to a vibrator located at the origin of three axes orthogonal to each other. If given, the natural law that Coriolis force acts in the third axial direction is utilized. Even if the axis is selected as shown in FIGS. 3 to 5, FIGS. It does not matter if the axis is selected as shown in the figure. Therefore, it is possible to perform detection by applying the basic principle shown in FIGS. 79 to 81 for all the embodiments described so far.

<7.5> Detection by Combination of Basic Principles As described above, in the angular velocity detection according to the present invention, the detection based on the basic principles shown in FIGS. 3 to 5 and the basics shown in FIGS. 79 to 81 are performed. Either detection based on the principle is possible, but furthermore, detection combining both is also possible. Here, in order to facilitate understanding, when the basic principles are arranged, it can be seen that six detection operations as shown in the following table are possible.

<U><F><ω> Principle diagram detection operation 1 X Y Z FIG. 81 detection operation 2 X Z Y FIG. 4 detection operation 3 Y Z X FIG. 79 detection operation 4 Y X Z FIG. 5 detection operation 5 Z X Y Fig. 80 Detecting operation 6 Z Y X Fig. 3

Here, the U column indicates the axial direction for exciting the vibrator, the F column indicates the axial direction for detecting the Coriolis force acting on the vibrator, and the ω column indicates the axis related to the angular velocity to be detected. The detection based on the basic principle shown in FIG. 3 to FIG. 5 is to perform even-numbered three detection operations in the above table, and the detection based on the basic principle shown in FIG. 79 to FIG. The odd three detection operations are performed. As described above, the angular velocity around the three axes of XYZ can be detected by such three detection operations.

  By the way, such a combination for detecting angular velocities around the three axes is not limited to the even-numbered and odd-numbered combinations. For example, the angular velocity around the three axes of XYZ can be detected even in the combination of the detection operations 1 to 3 in the first half, and the angular velocity around the three axes of XYZ can be detected in the combination of the detection operations 4 to 6 in the latter half (see the table above). (See column ω). Moreover, when such a combination is adopted, a part of the vibration mechanism and the detection mechanism can be omitted. For example, in order to execute the detection operations 1 to 3 in the above table, the excitation axes of the vibrator need only be the X axis and the Y axis (see the column U). In other words, it is not necessary to vibrate the vibrator in the Z-axis direction. Further, the Coriolis force detection axes need only be the Y axis and the Z axis (see column F). In other words, it is not necessary to detect the Coriolis force in the X-axis direction. As a result, it is sufficient for the vibration mechanism to be able to vibrate in the two axial directions of the X axis and the Y axis, and it is sufficient for the detection mechanism to be able to detect the two axial directions of the Y axis and the Z axis. Each of the various embodiments described so far is premised on including a vibration mechanism that vibrates in the three axial directions of XYZ and a detection mechanism that detects Coriolis force in the three axial directions of XYZ. However, by properly combining the basic principles as described above, it is possible to detect angular velocities about three axes by the biaxial vibration mechanism and the biaxial detection mechanism.

  In addition, all of the embodiments so far have been related to a three-dimensional angular velocity sensor that detects angular velocities about three axes of XYZ. If this is sufficient, a two-dimensional angular velocity sensor in which a part of the vibration mechanism or the detection mechanism is further omitted can be used. For example, consider only detection operation 1 and detection operation 2 in the above table. In order to perform these two detection operations, it is sufficient to have a vibration mechanism in the X-axis direction and a detection mechanism in the Y-axis and Z-axis directions. As a result, the angular velocity around the Z-axis and the Y-axis The surrounding angular velocity can be detected. Therefore, a two-dimensional angular velocity sensor can be realized by a vibration mechanism in one axis direction and a detection mechanism for two axes.

  Alternatively, the following combinations are possible. Now consider only detection operation 2 and detection operation 3 in the above table. In order to perform these two detection operations, it is sufficient to have a vibration mechanism in the X-axis and Y-axis directions and a detection mechanism in the Z-axis direction. As a result, the angular velocity around the Y-axis and the X-axis The surrounding angular velocity can be detected. Therefore, a two-dimensional angular velocity sensor can be realized by the biaxial vibration mechanism and the single axis detection mechanism.

  In addition, when vibrating the vibrator in the angular velocity sensor according to the present invention, it is preferable to vibrate at a resonance frequency unique to each vibrator. Each of the vibrators 130, 211, 241, 260, 321, 440, 550, and 610 in the above-described embodiments has a unique resonance frequency. By vibrating each vibrator at such a unique resonance frequency, a large vibration can be generated with a small supply energy, and the efficiency becomes very high.

  The multi-axis angular velocity sensor according to the present invention separately and independently detects an angular velocity ωx around the X axis, an angular velocity ωy around the Y axis, and an angular velocity ωz around the Z axis for an object moving in an XYZ three-dimensional coordinate system. be able to. Therefore, it is mounted on industrial machines, industrial robots, automobiles, airplanes, ships, etc., and can be widely used as sensors for recognizing motion states or performing feedback control for motions. It can also be used for control for correcting camera shake during shooting by the camera.

It is a perspective view which shows the basic principle of the one-dimensional angular velocity sensor using the Coriolis force proposed conventionally. It is a figure which shows the angular velocity around each axis | shaft in the XYZ three-dimensional coordinate system used as the detection target of this invention. It is a figure explaining the basic principle which detects angular velocity (omega) x around an X-axis by this invention. It is a figure explaining the basic principle which detects angular velocity (omega) y around the Y-axis by this invention. It is a figure explaining the basic principle which detects angular velocity (omega) z around Z-axis by this invention. It is a sectional side view which shows the structure of the multiaxial angular velocity sensor which concerns on 1st Example of this invention. It is a top view of the flexible substrate 110 of the multi-axis angular velocity sensor shown in FIG. It is a bottom view of the fixed board | substrate 120 of the multi-axis angular velocity sensor shown in FIG. 7 is a side sectional view showing a state in which a vibrator 130 in the multi-axis angular velocity sensor shown in FIG. 6 is displaced in the X-axis direction. FIG. FIG. 7 is a side sectional view showing a state in which a vibrator 130 in the multiaxial angular velocity sensor shown in FIG. 6 is displaced in the −X axis direction. FIG. 7 is a side sectional view showing a state in which a vibrator 130 in the multi-axis angular velocity sensor shown in FIG. 6 is displaced in the Z-axis direction. It is a figure which shows the supply voltage waveform for giving the vibration Ux of the X-axis direction with respect to the vibrator | oscillator 130 in the multi-axis angular velocity sensor shown in FIG. It is a figure which shows the supply voltage waveform for giving the vibration Uy of the Y-axis direction with respect to the vibrator | oscillator 130 in the multi-axis angular velocity sensor shown in FIG. It is a figure which shows the supply voltage waveform for giving the vibration Uz of a Z-axis direction with respect to the vibrator | oscillator 130 in the multi-axis angular velocity sensor shown in FIG. 7 is a side sectional view showing a phenomenon in which Coriolis force Fy is generated based on angular velocity ωx when vibration Uz is applied to vibrator 130 in the multi-axis angular velocity sensor shown in FIG. 6. FIG. 7 is a side sectional view showing a phenomenon in which Coriolis force Fz is generated based on angular velocity ωy when vibration Ux is applied to vibrator 130 in the multi-axis angular velocity sensor shown in FIG. 6. FIG. 7 is a side sectional view showing a phenomenon in which a Coriolis force Fx is generated based on an angular velocity ωz when a vibration Uy is applied to a vibrator 130 in the multiaxial angular velocity sensor shown in FIG. 6. 3 is a circuit diagram illustrating an example of a circuit for detecting a change in capacitance value of a capacitive element C. FIG. FIG. 19 is a timing chart for explaining the operation of the circuit shown in FIG. 18. FIG. It is a circuit diagram which shows an example of the circuit for detecting the change of the capacitance value of a pair of electrostatic capacitance elements C1, C2. FIG. 21 is a timing chart illustrating operation of the circuit illustrated in FIG. 20. It is a sectional side view explaining the principle of the 1st modification of the multiaxial angular velocity sensor shown in FIG. It is another sectional side view explaining the principle of the 1st modification of the multiaxial angular velocity sensor shown in FIG. FIG. 7 is still another side sectional view for explaining the principle of the first modification of the multi-axis angular velocity sensor shown in FIG. 6. It is a sectional side view which shows the specific structure of the 1st modification of the multi-axis angular velocity sensor shown in FIG. It is a figure which shows an example of the application method of the voltage to each electrode of the multiaxial angular velocity sensor shown in FIG. FIG. 7 is a side sectional view showing a specific structure of a second modification of the multiaxial angular velocity sensor shown in FIG. 6. It is a sectional side view which shows the structure of the multiaxial angular velocity sensor which concerns on the 2nd Example of this invention. It is a top view of the flexible substrate 210 of the multi-axis angular velocity sensor shown in FIG. It is a sectional side view which shows the cross section in another position of the multiaxial angular velocity sensor shown in FIG. FIG. 29 is a bottom view of the fixed substrate 230 of the multi-axis angular velocity sensor shown in FIG. 28. FIG. 29 is a side sectional view showing a first modification of the multiaxial angular velocity sensor shown in FIG. 28. FIG. 29 is a side sectional view showing a second modification of the multiaxial angular velocity sensor shown in FIG. 28. It is a top view of the flexible substrate 250 of the multi-axis angular velocity sensor shown in FIG. It is a sectional side view which shows the structure of the multiaxial angular velocity sensor which concerns on the 3rd Example of this invention. FIG. 36 is a top view of the flexible substrate 310 of the multiaxial angular velocity sensor shown in FIG. 35. It is a figure which shows arrangement | positioning of the resistive element R shown by FIG. FIG. 36 is a side sectional view showing a state in which Coriolis force Fx is applied to the multi-axis angular velocity sensor shown in FIG. FIG. 36 is a circuit diagram showing an example of a circuit that detects a Coriolis force Fx in the X-axis direction that acts on the multi-axis angular velocity sensor shown in FIG. 35. FIG. 36 is a circuit diagram showing an example of a circuit that detects a Coriolis force Fy in the Y-axis direction that acts on the multi-axis angular velocity sensor shown in FIG. 35. FIG. 36 is a circuit diagram showing an example of a circuit for detecting a Coriolis force Fz in the Z-axis direction that acts on the multi-axis angular velocity sensor shown in FIG. 35. It is a sectional side view which shows the structure of the multiaxial angular velocity sensor which concerns on the 4th Example of this invention. It is a figure which shows the polarization characteristic of the piezoelectric element used for the multi-axis angular velocity sensor shown in FIG. FIG. 43 is a side sectional view showing a state in which a displacement in the X-axis direction is caused in the multiaxial angular velocity sensor shown in FIG. 42. FIG. 43 is a side sectional view showing a state in which displacement in the Z-axis direction is caused in the multiaxial angular velocity sensor shown in FIG. 42. 43 is a wiring diagram showing wiring for detecting a Coriolis force Fx in the X-axis direction that has acted on the multi-axis angular velocity sensor shown in FIG. 42. FIG. 43 is a wiring diagram showing wiring for detecting a Coriolis force Fy in the Y-axis direction that has acted on the multi-axis angular velocity sensor shown in FIG. 42. FIG. FIG. 43 is a wiring diagram showing wiring for detecting a Coriolis force Fz in the Z-axis direction that has acted on the multi-axis angular velocity sensor shown in FIG. 42. It is a figure which shows the polarization characteristic contrary to the polarization characteristic shown in FIG. FIG. 43 is a plan view showing a distribution of polarization characteristics of a piezoelectric element used in a first modification of the multiaxial angular velocity sensor shown in FIG. 42. It is a wiring diagram which shows the wiring for detecting the Coriolis force Fx of the X-axis direction which acted on the multi-axis angular velocity sensor using the piezoelectric element shown in FIG. It is a wiring diagram which shows the wiring for detecting the Coriolis force Fy of the Y-axis direction which acted on the multi-axis angular velocity sensor using the piezoelectric element shown in FIG. It is a wiring diagram which shows the wiring for detecting the Coriolis force Fz of the Z-axis direction which acted on the multi-axis angular velocity sensor using the piezoelectric element shown in FIG. FIG. 43 is a side sectional view showing a structure of a second modification of the multi-axis angular velocity sensor shown in FIG. 42. FIG. 43 is a side sectional view showing a structure of a third modification of the multi-axis angular velocity sensor shown in FIG. 42. FIG. 43 is a side sectional view showing a structure of a fourth modification of the multiaxial angular velocity sensor shown in FIG. 42. It is a top view which shows the structure of the multi-axis angular velocity sensor which concerns on the 5th Example of this invention. FIG. 58 is a side sectional view showing the structure of the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a top view showing an arrangement of localized elements defined in the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a diagram showing polarization characteristics of a piezoelectric element used in the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a side cross-sectional view showing a state where displacement in the X-axis direction is caused in the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a side cross-sectional view showing a state where displacement in the Z-axis direction is caused in the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a wiring diagram showing wiring for detecting a Coriolis force Fx in the X-axis direction that acts on the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a wiring diagram showing wiring for detecting a Coriolis force Fy in the Y-axis direction that has acted on the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a wiring diagram showing wiring for detecting a Coriolis force Fz in the Z-axis direction applied to the multi-axis angular velocity sensor shown in FIG. 57. It is a figure which shows the polarization characteristic contrary to the polarization characteristic shown in FIG. FIG. 58 is a plan view showing a distribution of polarization characteristics of a piezoelectric element used in a first modification of the multiaxial angular velocity sensor shown in FIG. 57. FIG. 68 is a side sectional view showing a state in which a Coriolis force Fx in the X-axis direction acts on a multi-axis angular velocity sensor using the piezoelectric element shown in FIG. 67. FIG. 68 is a side sectional view showing a state in which a Coriolis force Fz in the Z-axis direction acts on a multi-axis angular velocity sensor using the piezoelectric element shown in FIG. 67. FIG. 68 is a wiring diagram showing wiring for detecting a Coriolis force Fx in the X-axis direction applied to the multi-axis angular velocity sensor using the piezoelectric element shown in FIG. 67. FIG. 68 is a wiring diagram showing wiring for detecting a Coriolis force Fy in the Y-axis direction applied to the multi-axis angular velocity sensor using the piezoelectric element shown in FIG. 67. FIG. 68 is a wiring diagram showing wiring for detecting a Coriolis force Fz in the Z-axis direction that has acted on the multi-axis angular velocity sensor using the piezoelectric element shown in FIG. 67. FIG. 58 is a side sectional view showing a structure of a second modification of the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a side sectional view showing a structure of a third modification of the multi-axis angular velocity sensor shown in FIG. 57. It is a perspective view which shows the basic principle of the multi-axis angular velocity sensor which concerns on the 6th Example of this invention. It is a sectional side view which shows the specific structure of the multi-axis angular velocity sensor which concerns on the 6th Example of this invention. It is a flowchart which shows the procedure of the detection operation | movement in the multiaxial angular velocity sensor which concerns on this invention. It is a figure which shows the specific circuit structural example for performing the detection operation in the multi-axis angular velocity sensor which concerns on this invention. It is a figure explaining another basic principle which detects angular velocity (omega) x around an X-axis by this invention. It is a figure explaining another basic principle which detects angular velocity (omega) y around the Y-axis by this invention. It is a figure explaining another basic principle which detects angular velocity (omega) z around Z-axis by this invention.

Explanation of symbols

10: vibrator 11, 12: piezoelectric element 20: object 30: vibrator 110: flexible substrate 120: fixed substrate 130: vibrator 140: sensor housing 151, 152: inverter 153: resistor 154: exclusive OR circuit 161 162: inverters 163, 164: resistance 165: exclusive OR circuits 171, 172: dielectric substrate 210: first substrate 211: vibrator 212: bridging portion 213: support frame 220: second substrate 221: depression 230 : Third substrate 231: cutting surface 240: fourth substrate 241: vibrator 242: pedestal 250: flexible substrate 251: action part 252: flexible part 253: fixed part 260: vibrator 270: pedestal 280: base Substrate 290: Lid substrate 310: First substrate 311: Action portion 312: Flexible portion 313: Fixed portion 320: Second substrate 321: Vibrator 322: Base 330: 3 substrate 331: depression 340: fourth substrate 350: power supply 361-363: voltmeter 410: flexible substrate 420: fixed substrate 430: piezoelectric element 440: vibrator 450: sensor housing 460: piezoelectric element 470: piezoelectric Element 480: Flexible substrate 490: Flexible substrate 510: Flexible substrate 520: Piezo element 530: Piezo element 540: Piezo element 550: Vibrator 560: Sensor housing 570: Flexible substrate 610: Vibrator 620: Sensor housing Body 630: Partition plate 640: Diaphragm 650: Connecting rod 660: Protection cover 700: Block 710: Vibrating unit 711: Vibration generating circuit 712: Multiplexer 720: Detection unit 721: Displacement detection circuit 722: Multiplexer 730: Detection Value output circuit 740: controller a: delay time b: pulse width / delay time C1 to C5: capacity Child / capacitance values [Delta] C, [Delta] C12, [Delta] C34: capacitance value differences D1-D16: localized elements d: pulse width / delay times d1, d2: delay times E0, E1-E5: upper electrode layers E1a-E5a: auxiliary electrode layers F0, F1 to F5: Lower electrode layers F1a to F5a: Auxiliary electrode layers F, Fx, Fy, Fz: Coriolis force f: Period G: Center of gravity G0: Upper electrode layers G1 to G5: Lower electrode layers G6 to G10: Upper electrodes Layers H1 to H4: Openings J1 to J6: Coils L1 to L16: Upper electrode layers M0, M1 to M16: Lower electrode layers N1 to N4: Node R: Piezoresistive elements Rx1 to Rx4: Piezoresistive elements Ry1 to Ry4: Piezo Resistive elements Rz1 to Rz4: Piezoresistive elements SW1 to SW6: Switches T1 to T4, Tx1, Ty1, Tz1, Tx2, Ty2, Tz2: Terminals t1 to t5: Periods U, Ux, Uy, Uz : Vibration V, V1 to V5: Voltage Vx, Vy, Vz: Bridge voltage W1, W2, X, Y, Z: Coordinate axes α, αx, αy, αz: Acceleration ω, ωx, ωy, ωz: Angular velocity

Claims (6)

A one-dimensional angular velocity sensor for detecting an angular velocity around the Y axis in an XYZ three-dimensional coordinate system,
A piezoelectric element;
A plurality of upper electrodes formed on the upper surface of the piezoelectric element;
A plurality of lower electrodes formed on the lower surface of the piezoelectric element and disposed at positions facing each of the plurality of upper electrodes;
A flexible substrate fixed to the lower surface of the lower electrode and having flexibility;
A vibrator fixed to the lower surface of the flexible substrate;
A sensor housing that supports the flexible substrate and accommodates the vibrator;
Excitation means for vibrating the vibrator in a predetermined direction by supplying an AC signal between a predetermined lower electrode and an upper electrode facing each other;
Detecting means for detecting a displacement of the vibrator in a predetermined direction by obtaining a voltage generated between a predetermined lower electrode and an upper electrode facing each other;
With
An XYZ three-dimensional coordinate system is defined in which the origin of the coordinate system is set at substantially the center of the flexible substrate, and the X axis and the Y axis intersect on a plane parallel to the main surface of the flexible substrate, and XY When defining an arbitrary W axis (not overlapping with the Y axis) that intersects the X axis at the position of the origin on the plane,
Of the plurality of upper electrodes, the first upper electrode is formed at a position where the projected image on the XY plane is at the negative portion of the X axis, and the second upper electrode is projected on the XY plane with the X axis. It is formed at a position that comes to the positive part of
Of the plurality of upper electrodes, the third upper electrode is formed at a position where the projected image on the XY plane is at the negative portion of the W axis, and the fourth upper electrode is projected on the XY plane with the W axis. It is formed at a position that comes to the positive part of
The excitation means performs a process of vibrating the vibrator in the X-axis direction by supplying an AC signal having a predetermined phase between the first and second upper electrodes and the lower electrodes facing the first and second upper electrodes. ,
The detection means detects a displacement in the Z-axis direction of the vibrator based on a voltage generated between the third and fourth upper electrodes and each lower electrode facing the third and fourth upper electrodes, and detects the detected displacement Is output as a value indicating the angular velocity around the Y-axis. A one-dimensional angular velocity sensor for detecting an angular velocity around the Z axis in an XYZ three-dimensional coordinate system,
A piezoelectric element;
A plurality of upper electrodes formed on the upper surface of the piezoelectric element;
A plurality of lower electrodes formed on the lower surface of the piezoelectric element and disposed at positions facing each of the plurality of upper electrodes;
A flexible substrate fixed to the lower surface of the lower electrode and having flexibility;
A vibrator fixed to the lower surface of the flexible substrate;
A sensor housing that supports the flexible substrate and accommodates the vibrator;
Excitation means for vibrating the vibrator in a predetermined direction by supplying an AC signal between a predetermined lower electrode and an upper electrode facing each other;
Detecting means for detecting a displacement of the vibrator in a predetermined direction by obtaining a voltage generated between a predetermined lower electrode and an upper electrode facing each other;
With
When an XYZ three-dimensional coordinate system is defined in which the origin of the coordinate system is set at substantially the center of the flexible substrate and the X axis and the Y axis intersect on a plane parallel to the main surface of the flexible substrate. ,
Of the plurality of upper electrodes, the first upper electrode is formed at a position where the projected image on the XY plane is at the negative portion of the X axis, and the second upper electrode is projected on the XY plane with the X axis. It is formed at a position that comes to the positive part of
Of the plurality of upper electrodes, the third upper electrode is formed at a position where the projected image on the XY plane comes to the negative portion of the Y axis, and the fourth upper electrode has the projected image on the XY plane having the Y axis. It is formed at a position that comes to the positive part of
The excitation means performs a process of vibrating the vibrator in the Y-axis direction by supplying an AC signal having a predetermined phase between the third and fourth upper electrodes and the lower electrodes facing the third and fourth upper electrodes. ,
The detection means detects a displacement in the X-axis direction of the vibrator based on a voltage generated between the first and second upper electrodes and each lower electrode facing the first and second upper electrodes, and detects the detected displacement Is output as a value indicating the angular velocity around the Z-axis. A one-dimensional angular velocity sensor for detecting an angular velocity around the X axis in an XYZ three-dimensional coordinate system,
A piezoelectric element;
A plurality of upper electrodes formed on the upper surface of the piezoelectric element;
A plurality of lower electrodes formed on the lower surface of the piezoelectric element and disposed at positions facing each of the plurality of upper electrodes;
A flexible substrate fixed to the lower surface of the lower electrode and having flexibility;
A vibrator fixed to the lower surface of the flexible substrate;
A sensor housing that supports the flexible substrate and accommodates the vibrator;
Excitation means for vibrating the vibrator in a predetermined direction by supplying an AC signal between a predetermined lower electrode and an upper electrode facing each other;
Detecting means for detecting a displacement of the vibrator in a predetermined direction by obtaining a voltage generated between a predetermined lower electrode and an upper electrode facing each other;
With
An XYZ three-dimensional coordinate system is defined in which the origin of the coordinate system is set at substantially the center of the flexible substrate, and the X axis and the Y axis intersect on a plane parallel to the main surface of the flexible substrate, and XY When an arbitrary W axis (not overlapping with the X axis) that intersects the Y axis at the position of the origin on the plane is defined,
Of the plurality of upper electrodes, the first upper electrode is formed at a position where the projected image on the XY plane is at the negative portion of the W axis, and the second upper electrode is projected on the XY plane with the W axis. It is formed at a position that comes to the positive part of
Of the plurality of upper electrodes, the third upper electrode is formed at a position where the projected image on the XY plane comes to the negative portion of the Y axis, and the fourth upper electrode has the projected image on the XY plane having the Y axis. It is formed at a position that comes to the positive part of
The excitation means performs a process of oscillating the vibrator in the Z-axis direction by supplying an AC signal having a predetermined phase between the first and second upper electrodes and the lower electrodes opposed to the first and second upper electrodes. ,
The detecting means detects a displacement of the vibrator in the Y-axis direction based on a voltage generated between the third and fourth upper electrodes and each lower electrode facing the third and fourth upper electrodes, and detects the detected displacement Is output as a value indicating the angular velocity around the X axis. The angular velocity sensor according to any one of claims 1 to 3,
  At least one of the first upper electrode and the first lower electrode is constituted by a pair of electrodes that are physically separated from each other,
  At least one of the second upper electrode and the second lower electrode is constituted by a pair of electrodes arranged physically apart from each other,
  At least one of the third upper electrode and the third lower electrode is constituted by a pair of electrodes that are physically separated from each other,
  An angular velocity sensor, wherein at least one of the fourth upper electrode and the fourth lower electrode is constituted by a pair of electrodes that are physically separated from each other. In the angular velocity sensor according to any one of claims 1 to 4,
  An angular velocity sensor using a plurality of physically divided piezoelectric elements. In the angular velocity sensor according to any one of claims 1 to 5,
  Any one of a plurality of lower electrodes or a plurality of upper electrodes is constituted by a single electrode layer.