JP2008058062A - Angular velocity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized angular velocity sensor having a simple structure, which detects a torsional vibration component in a Y-axis rotation system. <P>SOLUTION: The angular velocity sensor 1 is equipped with a piezoelectric vibration chip 10 acquired by forming, on an XY-plane: a base part 20; driving arms 40, 50 extended in parallel with the Y-axis from the base part 20 or the first connection arm 31 and the second connection arm 32 connected to the base part 20, for performing bending vibration in the X-axis direction orthogonal to the Y-axis; and a detection arm 60 parallel to the driving arms 40, 50. The sensor 1 is also equipped with a detection means for outputting a detection signal corresponding to a vibration component generated in the detection arm 60 by a Coriolis force applied by rotation around the Y-axis. The vibration component in the Y-axis rotation system is a torsional vibration component of the detection arm 60. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an angular velocity sensor, and more particularly to an angular velocity sensor that outputs a torsional vibration component generated in a detection arm in response to an angular velocity of a Y-axis rotation system as a detection signal.

  Angular velocity sensors (sometimes called gyroscopes) that detect rotational angular velocities are used in navigation systems, attitude control systems for aircraft and ships, attitude control systems for robots, etc., camera shake prevention devices for video cameras and digital cameras, etc. ing. These electronic devices are required to be reduced in size, and accordingly, the angular velocity sensor is also required to be reduced in size and simplified in configuration.

  2. Description of the Related Art Conventionally, a vibrator, excitation means for exciting drive vibration with respect to the vibrator, and detection means for detecting detection vibration generated in the vibrator due to rotation of the vibrator are provided. There is known an angular velocity sensor that detects an angular velocity of a Z-axis rotation system formed so as to extend in a predetermined plane intersecting Z (see, for example, Patent Document 1).

  An angular velocity that includes two tuning forks and is supported by joining ends of detection arms that extend in parallel to the tuning fork at the center of the two tuning forks to a frame provided around the two tuning forks. In the sensor, when the center of the surface on which the tuning fork and the detection arm are deployed is rotated as a rotation axis, a torsional vibration component around the rotation axis is generated in the detection arm, and an angular velocity sensor that detects this torsional vibration component is also known. (For example, refer to Patent Document 2).

JP-A-11-281372 United States Pent 4,654,663

  In Patent Document 1, an angular velocity sensor that can detect a vibration axis perpendicular to a surface on which a plurality of vibration systems are developed, that is, a vibration component of a Z-axis rotation system, and has an in-plane rotation axis. The vibration component of the shaft rotation system or the Y-axis rotation system cannot be detected. That is, the X-axis and Y-axis rotations are not detected.

Further, in Patent Document 2 described above, a torsional vibration component can be detected. However, since the detection arm is connected to the frame, noise is generated under the influence of angular velocity other than acceleration and torsion.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a small angular velocity sensor with a simple structure that realizes detection of a torsional vibration component of a Y-axis rotation system.

  An angular velocity sensor according to the present invention includes a drive arm that extends in parallel to the Y axis from the base or a connecting arm connected to the base and performs bending vibration in the X-axis direction orthogonal to the Y axis, and is parallel to the drive arm. A detection signal of the Y-axis rotation system in accordance with a vibration component generated in the detection arm by a Coriolis force in the Z-axis direction given by rotation around the Y axis and a piezoelectric vibrating piece formed on the XY plane. And detecting means for outputting.

  According to the present invention, the structure of the piezoelectric vibrating piece described above forms a drive arm and a detection arm in the XY plane, and vibration generated in the detection arm due to the Coriolis force in the Z-axis direction given by rotation around the Y-axis. By detecting the component, the angular velocity of the Y-axis rotation system can be detected.

  The piezoelectric vibrating piece extends from the base in the Y-axis direction, the second detection arm extends in the minus Y-axis direction, and extends from the base in the X-axis direction. A first connecting arm; a second connecting arm extending in the minus X-axis direction from the base; and a driving arm connected to the first connecting arm and extending in the Y-axis direction and the minus Y-axis direction. And a driving arm connected to the second connecting arm and extending in the Y-axis direction and the minus Y-axis direction.

  The angle sensor configured as described above has the same form as a WT type angular velocity sensor (double T type), and is used for an angular velocity sensor of a Z-axis rotation system. Since the WT type angular velocity sensor is independent of the drive system and the detection system, it is known that the leakage signal is small and the detection sensitivity is high, and high detection sensitivity is also realized in the detection of the angular velocity of the Y-axis rotation system.

  In the structure of the angular velocity sensor described above, the vibration component generated in the first detection arm and the second detection arm by the Coriolis force in the Z-axis direction given by the rotation about the Y-axis is a torsional vibration component. It is characterized by that.

  The WT type angular velocity sensor configured as described above is known as an angular velocity sensor that detects a vibration component of the Z-axis rotation system, and the vibration component of the Z-axis rotation system is a bending vibration component of the first and second detection arms. . Therefore, since the vibration mode is different from the torsional vibration of the detection arm according to the present invention, the vibration component of the Y-axis rotation system orthogonal to the Z-axis can be detected with the influence of the detection signal of the Z-axis rotation system being minimized.

  Further, the torsional vibration generated by the Coriolis force in the Z-axis direction given by the rotation about the Y-axis is visually recognized from the base portion, and the torsional vibration direction of the first detection arm and the torsion of the second detection arm. The vibration direction is the reverse direction, and each vibration amplitude is substantially the same.

  In this way, since the output signals from the first detection arm and the second detection arm are in opposite phases, the signal intensity of the detection signal obtained by synthesizing the two output signals is doubled, and noise (S / N ratio) can be suppressed, so that the detection sensitivity is increased.

  Further, a weight portion is formed at each tip of the drive arm and the detection arm, and the width D of the weight portion of the detection arm is 5d ≦ D ≦ 10d with respect to the width d of the detection arm portion of the detection arm. It is preferable that the range is set.

  The vibration component of the Y-axis rotation system is a torsional vibration component. Therefore, by designing the width of the weight portion to be larger than the width of the vibration portion and designing it within a predetermined range, it is easy to generate torsional vibration and the detection sensitivity can be increased. Moreover, there is an effect that the adjustment range of the detected detuning frequency described later can be reduced, and the productivity can be increased.

Moreover, it is preferable that the detection sensitivity of the torsional vibration component of the Y-axis rotation system is adjusted by the detection detuning frequency of the first detection arm and the second detection arm.
Here, the detected detuning frequency means a difference between the drive frequency and the detected frequency.

  Although details will be described in an embodiment described later, the detection signal of the Z-axis rotation system is superimposed when the Y-axis rotation system is detected. Further, the Y-axis rotation system sensitivity and the Z-axis rotation system sensitivity show a substantially inversely proportional tendency. The Z-axis rotation system sensitivity is the other-axis sensitivity with respect to the Y-axis rotation system sensitivity, and the other-axis sensitivity is noise. Here, by adjusting the detected detuning frequency to an appropriate value, the degree of influence on the Y-axis sensitivity of the Y-axis rotation system of the other-axis sensitivity can be reduced, and as a result, the detection sensitivity of the Y-axis rotation system can be increased. it can.

  The detection detuning frequency is preferably adjusted by increasing or decreasing the mass of the weight portion provided at the tip of each of the first detection arm and the second detection arm.

  Since the vibration component of the Y-axis rotation system described above is a torsional vibration component, the detected detuning frequency can be effectively adjusted by increasing or decreasing the mass of the weight portion that is wider than the first and second detection arms. .

  Further, it is preferable that the mass of the weight portion is increased or decreased sequentially from the width direction end portion of the weight portion toward the center.

  The torsional vibration component is detected in the Z-axis rotation system. Therefore, by performing mass increase / decrease from the end in the width direction of the weight that easily affects torsional vibration, the detected detuning frequency can be adjusted with a small mass increase / decrease, and the adjustment time can be shortened.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 shows the structure of the angular velocity sensor of the present invention, FIG. 2 shows a vibration mode when no rotational angular velocity is applied, FIG. 3 shows a vibration mode of the Z-axis rotation system, and FIGS. 4 to 6 show vibration modes of the Y-axis rotation system. FIG. 7 is a graph showing sensitivity characteristics.
Note that the drawings referred to in the following description are schematic views in which the vertical and horizontal scales of members or portions are different from actual ones for convenience of illustration.
(Embodiment)

  FIG. 1 is a perspective view showing the structure of an angular velocity sensor according to an embodiment of the present invention. In FIG. 1, an angular velocity sensor 1 according to this embodiment includes a piezoelectric vibrating piece 10, a detection circuit (not shown) as detection means, and an oscillation circuit as excitation means. The piezoelectric vibrating piece 10 can be formed of a known piezoelectric material. In the present embodiment, a quartz vibrating piece will be described as an example.

The piezoelectric vibrating piece 10 is formed in the XY plane. In the present embodiment, the piezoelectric vibrating piece 10 is made of quartz, and is a Z-cut of the X-axis called the electric axis, the Y-axis called the mechanical axis, and the Z-axis called the optical axis and the Y-axis cut in the plane direction. It is formed of a quartz substrate.
The planar shape of the piezoelectric vibrating piece 10 is developed on the XY plane in accordance with the crystal axis of the crystal, and is 180 ° point-symmetric with respect to the gravity center position G.

  The piezoelectric vibrating piece 10 is formed with a rectangular base 20 having end faces parallel to the X-axis direction and the Y-axis direction, respectively, and extends parallel to the X-axis from the center of the two end faces of the base 20 parallel to the Y-axis. A pair of drive arms 40, 50 parallel to the Y axis from the distal ends of the first connecting arm 31 and the second connecting arm 32 and a center of two end faces of the base 20 parallel to the X axis are parallel to the Y axis. A detection arm 60 extending on a straight line is formed. The drive arm 40 includes a first connecting arm 31 extending from the end face of the base portion 20 in the X-axis direction, and two driving arms 40 extending in the Y-axis direction and the minus Y-axis direction perpendicular to the first connecting arm 31. The vibration parts 41 and 42 are comprised. Similarly, the drive arm 50 includes two vibrating portions 51 and 52 that are orthogonal to the second connecting arm 32 extending in the minus X-axis direction from the base portion 20 and extend in the Y-axis direction and the minus Y-axis direction. Has been.

  At the tips of the vibration parts 41, 42, 51, 52, substantially square weight parts 43, 44, 53, 54 wider than the respective vibration parts are formed.

  The detection arm 60 includes detection arm portions 61 and 62 extending from the two end portions of the base portion 20 on the straight lines in the Y-axis direction and the negative Y-axis direction, and each of the detection arm portions 61 and 62 formed at the tips of the detection arm portions 61 and 62. It is composed of substantially rectangular weight parts 63 and 64 that are wider than the detection arm part.

  Here, the widths (indicating the width in the X-axis direction) of the weight parts 63 and 64 formed at the tips of the detection arm parts 61 and 62 are set larger than those of the other weight parts 43, 44, 53 and 54. The weights 63 and 64 are designed so that 5d ≦ D ≦ 10d, where D is the width of the weights 63 and 64, and d is the width of the detection arm portions 61 and 62. That is, the widths of the weight parts 63 and 64 are designed in a range of 5 to 10 times the width d of the detection arm parts 61 and 62.

  The reason why the weight parts 63 and 64 are set in this way is to efficiently generate torsional vibration of the detection arm 60 in the angular velocity detection of the Y-axis rotation system described later (see FIGS. 4 to 6).

A concave groove 45, 46, 55, 56, 65, 66 is formed in the thickness direction at the center in the width direction of each of the vibration parts 41, 42, 51, 52 and the detection arm parts 61, 62.
The weights 43, 44, 53, 54, 63, 64 and the grooves 45, 46, 55, 56, 65, 66 are provided to reduce the size of the piezoelectric vibrating piece 10. The invention is not particularly limited.

  The drive arms 40 and 50 have the widths and lengths of the vibration parts 41, 42, 51, and 52, the dimensions of the weight parts 43, 44, 53, and the grooves 45 and 46 so that the drive vibration of a predetermined frequency is generated. , 55 and 56 are set. In addition, the width and length of the detection arm portions 61 and 62, the dimensions of the weight portions 63 and 64, and the dimensions of the grooves 65 and 66 are set in the detection arm 60 so that predetermined detection vibration is generated.

  The piezoelectric vibrating piece 10 having the shape as described above is generally called a WT type piezoelectric vibrating piece and is advantageous for downsizing and high accuracy. The width of the detection arm portions 61 and 62 and the weight portion 63, Except for the relationship with the width of 64, the configuration is the same as that of the WT type already proposed.

  The drive arms 40 and 50 and the detection arm 60 are formed with drive electrodes and detection electrodes (not shown), respectively. These drive electrodes and detection electrodes are connected from the back surface of the base 20 to a detection circuit and an oscillation circuit (not shown). The base 20 is connected to and supported by the substrate via leads or bonding wires. The substrate is fixed inside the package. With such a configuration, when an external impact is applied, the lead or the bonding wire absorbs the impact, so that the generation of noise can be suppressed. Alternatively, the drive electrode and the detection electrode may be electrically connected to the drive circuit or the detection circuit via a lead or a bonding wire. The detection circuit and the oscillation circuit have the same configuration as that used in the conventional WT type piezoelectric vibrating piece. Further, each drive electrode and detection electrode are formed symmetrically with respect to the gravity center position G by 180 °.

Subsequently, the operation of the piezoelectric vibrating reed 10 of the present embodiment described above, the vibration mode of the conventional Z-axis rotation system and the rotation system around the Y-axis of the present embodiment (hereinafter simply referred to as the Y-axis rotation system). Will be described.
FIG. 2 is an explanatory view schematically showing a vibration mode (no rotation is applied) of the piezoelectric vibrating piece of the present embodiment, and FIG. 3 is an explanatory view schematically showing a vibration mode of the Z-axis rotation system. 2 and 3, the drive arms 40 and 50 and the detection arm 60 are simplified and represented by lines in order to easily express the vibration form. The same components as those in FIG. 1 are denoted by the same reference numerals, and the description of the structure is omitted.

  First, the static operation of the piezoelectric vibrating piece 10 (vibration mode when no rotational acceleration is applied) will be described. In FIG. 2, the drive vibration is a bending vibration indicated by an arrow A of the vibration parts 41, 42, 51, 52, and a vibration state indicated by a solid line and a vibration state indicated by a two-dot chain line are repeated at a predetermined frequency. . At this time, the balance between the vibrating portions 41 and 42 and the vibrating portions 51 and 52 is adjusted, and vibration is performed in line symmetry with respect to the Y axis passing through the gravity center position G. Therefore, the base portion 20, the first connecting arm 31, The second connecting arm 32 and the detection arm portions 61 and 62 hardly vibrate.

  Next, the operation when the rotational angular velocity ω around the Z axis is applied will be described. In FIG. 3, in the Z-axis rotation system, the detected vibration repeats a vibration state indicated by a solid line and a vibration state indicated by a two-dot chain line. The detected vibration is applied to the drive arms 40 and 50 when a rotational angular velocity ω around the Z-axis is applied to the piezoelectric vibrating piece 10 in a state where the piezoelectric vibrating piece 10 performs the driving vibration (bending vibration) shown in FIG. It is generated by the Coriolis force in the direction indicated by the arrow B.

  Due to the Coriolis force in the direction of arrow B, the driving arms 40 and 50 vibrate in the circumferential direction with respect to the gravity center position G. At the same time, as shown by an arrow C, the detection arm portions 61 and 62 perform bending vibration in the direction opposite to the arrow B in response to the vibration of the arrow B.

  The drive electrode and the detection electrode formed on the piezoelectric vibrating piece 10 are electrically connected to the detection circuit and the oscillation circuit (both mounted on the semiconductor device) via the connection electrode formed on the base 20. (Both not shown). As a result, the piezoelectric vibrating piece 10 bends and vibrates by the oscillation circuit, and outputs a detection signal corresponding to the angular velocity from the detection arm 60 to the detection circuit. Then, an electrical signal corresponding to the angular velocity is output by the semiconductor device.

  In the Z axis rotation system, the detection sensitivity of the Y axis rotation system or the X axis rotation system perpendicular to the Z axis can be ignored.

Subsequently, the operation of the Y-axis rotation system in the present embodiment will be described with reference to the drawings.
4 to 6 show vibration modes of the Y-axis rotation system, FIG. 4 is a perspective view, and FIGS. 5 and 6 are upper side views showing a state viewed from above (in the direction of arrow A) in FIG. When a rotational angular velocity ω is applied around the Y axis in a state in which the drive arms 40 and 50 are flexurally vibrated, the drive arms 40 and 50 cause the flexural vibration in the X direction and the Z direction by the Coriolis force as shown in FIG. Vibrates in a vibration mode that combines axial bending vibrations.

  In other words, due to the Coriolis force, the driving arm 40 bends and vibrates in the Z direction with the first connecting arm 31 as the axis of vibration and the driving arm 50 has the second connecting arm 32 in the opposite phase with respect to the axis of vibration. To do. Then, torsional vibration in the direction of arrow T is generated in the detection arm 60. By detecting this torsional vibration, a detection signal corresponding to the angular velocity is output to the detection circuit. Then, an electrical signal corresponding to the angular velocity is output by the semiconductor device.

  The relationship between Coriolis force and torsional vibration (detected vibration) in the Y-axis rotation system will be described in more detail with reference to FIGS. FIG. 5 illustrates a case where the driving arms 40 and 50 vibrate in the outer direction (indicated by an arrow + V in the drawing). The driving arm 40 is moved in the + Z direction by the Coriolis force F, and the driving arm 50 is moved in the −Z direction. Transforms into Then, the detection arm 60 is twisted and deformed in a direction (+ T direction) to cancel the Coriolis force F.

FIG. 6 illustrates a case where the driving arms 40 and 50 vibrate in the inner direction (indicated by an arrow −V in the figure). The driving arm 40 is moved in the −Z direction by the Coriolis force F, and the driving arm 50 is + Z. Vibration deformation in the direction. Then, the detection arm 60 is twisted and deformed in a direction (-T direction) to cancel the Coriolis force F.
In this way, the detection arm 60 repeats torsional vibrations as shown in FIGS. 5 and 6 due to the Coriolis force F, and outputs a detection signal to detect the angular velocity of the Y-axis rotation system.
In the case of the X-axis rotating system, no detection signal is output to the detection arm 60 because no Coriolis force is generated.

  As described above, the bending vibration in the X-axis direction of the detection arm 60 can be detected as a detection signal for the Z-axis rotation system, and the torsional vibration of the detection arm 60 can be detected as a detection signal for the Y-axis rotation system. Can do.

  Note that the detection arm on the Y-axis (+ Y-axis) side and the detection arm on the negative Y-axis side are visually oscillated in the opposite directions when viewed from the base 20. Therefore, each detection arm outputs a detection signal having an antiphase, and by synthesizing this detection signal, the output becomes twice the output from one detection arm, and the detection sensitivity is increased.

  Further, it is confirmed by experiment that the detection signal of the Z-axis rotation system is superposed on the detection signal of the Y-axis rotation system, but the detection signal of the Z-axis rotation system is added to the detection signal of the Y-axis rotation system. On the other hand, it is noise. When rotating around the Y axis, the Coriolis force of the X axis rotating system is not generated and can be ignored.

Next, a description will be given of minimizing the detection signal of the Z-axis rotation system positioned as noise. Description will be made using the Y-axis sensitivity of the Y-axis rotation system and the Z-axis sensitivity of the Y-axis rotation system. The Z-axis sensitivity is expressed as the other-axis sensitivity with respect to the Y-axis sensitivity in the Y-axis rotation system. Further, the ratio of the Z-axis sensitivity to the Y-axis sensitivity is expressed as the other-axis sensitivity ratio.
FIG. 7 is a graph showing sensitivity characteristics. The horizontal axis represents the detected detuning frequency, the left vertical axis represents the detection sensitivity (simply expressed as sensitivity), and the right vertical axis represents the other axis sensitivity ratio (simply expressed as sensitivity ratio).

  In FIG. 7, the Y-axis sensitivity increases in a curve as the detected detuning frequency approaches 0 Hz. On the other hand, the Z-axis sensitivity changes in an inversely proportional direction to the Y-axis sensitivity, and tends to decrease when approaching 0 Hz. Therefore, the other-axis sensitivity ratio changes linearly, and is about 50% when the detected detuning frequency is approximately in the vicinity of −1200 Hz, which is greatly influenced by the Z-axis sensitivity.

  In the present embodiment, the other-axis sensitivity ratio shows a minimum value around −409 Hz in the calculation, and the other-axis sensitivity ratio can be suppressed to 5% or less in the range of −409 Hz ± 73 Hz. If the other-axis sensitivity ratio is 5% or less, it can be sufficiently put into practical use as an angular velocity sensor of the Y-axis rotation system.

  As described above, the detection sensitivity can be adjusted by adjusting the detection detuning frequency. However, as shown in FIG. 7, the Y-axis sensitivity and the Z-axis sensitivity are in a substantially inversely proportional relationship. On the other hand, it is only necessary to adjust so that the detuning frequencies of the Z-axis rotation system and the Y-axis rotation system cancel each other. In other words, by adjusting the detuning frequency of the Y axis rotation system to the minus side and the detuning frequency of the Z axis rotation system to the plus side, the other axis sensitivity (other axis sensitivity ratio) in the Y axis rotation system is suppressed. Can do.

The detuning frequency adjustment of the Y-axis rotation system is performed by adding or removing mass in the weight parts 63 and 64 (see FIG. 1). Here, an example of removing mass will be described.
Au layers are formed in advance on both the front and back surfaces of the weight parts 63 and 64. This Au layer has an additional mass, and this Au layer is removed using a laser so as to have a predetermined detuning frequency.

  At this time, the weights 63 and 64 are removed linearly in the longitudinal direction from the outer end or inner end in the width direction and gradually removed toward the inner end. As described above, since the detection of the Y-axis rotation system detects the torsional vibration component, the detuning frequency can be adjusted efficiently by removing the mass from the outside in the width direction of the weight part that easily affects the torsional vibration.

  Further, when the detuning frequency adjustment of the weight parts 63 and 64 is performed by removing the mass, the Au layer is formed so that the detected detuning frequency is in the minus direction with respect to the target frequency. In this embodiment, the Y-axis detuning frequency is set to, for example, about −800 Hz, and is adjusted to a range of −409 Hz ± 73 Hz by mass removal.

  On the other hand, the detailed description of the adjustment of the detected detuning frequency by adding mass is omitted, but it is possible by applying the above-described concept of mass removal. That is, the Y-axis detuning frequency may be set in advance on the plus side, and mass may be added to the weights 63 and 64 by ion plating or vapor deposition.

  The weights 63 and 64 add and remove mass so that the torsional vibrations are balanced (detection frequency and amplitude are balanced).

  Therefore, according to the above-described embodiment, the structure of the piezoelectric vibrating piece 10 includes the drive arms 40 and 50 and the detection arm 60 in the XY plane, and has the same structure as the conventional angular velocity sensor of the Z-axis rotation system. The vibration component generated in the detection arm 60 can be detected by the Coriolis force given by the rotation about the Y axis.

  Further, the piezoelectric vibrating piece 10 having the above-described form is a form called a WT type angular velocity sensor (double T type). It is known that the WT type angular velocity sensor has high detection sensitivity, and high detection sensitivity can be realized even in the detection of the angular velocity of the Y-axis rotation system.

  Further, the vibration component of the Z-axis rotation system in the WT type is a bending vibration component of the detection arm 60. Therefore, since the vibration mode is different from the torsional vibration of the detection arm 60 of the Y-axis rotation system, the vibration component of the Y-axis rotation system can be accurately detected without being affected by the vibration component of the Z-axis rotation system.

  Further, the torsional vibration direction of the detection arm portion 61 and the torsional vibration direction of the detection arm portion 62 as viewed from the base portion 20 are opposite to each other, and the respective vibration amplitudes are substantially the same. Accordingly, the signal intensity of the detection signal obtained by combining the two output signals is doubled, and noise (S / N ratio) can be suppressed, so that the detection sensitivity can be increased.

  Furthermore, since the vibration component of the Y-axis rotation system is a torsional vibration component, the width D of the weight parts 63 and 64 of the detection arm 60 is 5d ≦ D ≦ 10d with respect to the width d of the detection arm parts 61 and 62. By setting to this range, torsional vibration can be easily generated, and the adjustment range of the detected detuning frequency can be reduced.

  In the structure of the piezoelectric vibrating piece 10 described above, the detection signal of the Z-axis rotation system is superimposed when the Y-axis rotation system is detected. Further, the Y-axis rotation system sensitivity and the Z-axis rotation system sensitivity show a substantially inversely proportional tendency. The Z-axis rotation system sensitivity (other-axis sensitivity) is noise relative to the Y-axis rotation system sensitivity. Here, by adjusting the detected detuning frequency of the Y-axis rotation system to an appropriate value of the other-axis sensitivity ratio of 5% or less, the degree of influence of the other-axis sensitivity on the sensitivity of the Y-axis rotation system is reduced, and as a result The sensitivity of the Y-axis rotation system can be increased.

  The above-described adjustment of the detected detuning frequency of the Y-axis rotation system is performed by increasing / decreasing the mass of the weight portions 63 and 64 provided on the detection arm 60, and is performed from the width direction end portion of the weight portion toward the center. Since the torsional vibration component of the detection arm 60 is detected in the Y-axis rotation system, the detection detuning can be performed with a small mass increase / decrease by increasing / decreasing the mass from the end in the width direction of the weight part that easily affects the torsional vibration. It is possible to adjust the detection sensitivity by adjusting the frequency.

It should be noted that the present invention is not limited to the above-described embodiment, but includes modifications and improvements as long as the object of the present invention can be achieved.
For example, in the above-described embodiment, the WT type piezoelectric vibrating piece has been described as an example. However, the present invention can also be applied to a piezoelectric vibrating piece called an H type, a tuning fork type vibrating piece, and other forms. These can be realized by designing one of the two-axis rotation systems so that the detection arm is flexibly oscillated by the Coriolis force and the other is torsionally oscillated.

  Therefore, according to the present invention, it is possible to provide a small angular velocity sensor with a simple structure that realizes detection of the torsional vibration component of the Y-axis rotation system.

  The above-described angular velocity sensor according to the present invention can be mounted on various electronic devices. For example, it can be applied to camera shake correction of a digital camera, an impact detection sensor such as an HDD (Hard Disk Drive), or the like.

  For example, in a thin digital camera, since a circuit board or the like is arranged perpendicular to the optical axis, it is difficult to arrange the Z-axis of the angular velocity sensor perpendicular to the optical axis. If the angular velocity sensor capable of detecting the Y-axis rotation system of the invention is mounted, the angular velocity sensor can be disposed in parallel to the circuit board, so that the digital camera can be thinned.

The perspective view which shows the structure of the angular velocity sensor which concerns on embodiment of this invention. Explanatory drawing which shows typically the vibration mode when the rotational acceleration of the piezoelectric vibrating piece which concerns on embodiment of this invention is not applied. Explanatory drawing which shows typically the vibration mode of the Z-axis rotation system which concerns on embodiment of this invention. The perspective view which shows the vibration mode of the Y-axis rotation system which concerns on embodiment of this invention. The upper side view which shows the state visually recognized from the upper direction (arrow A direction) of FIG. The upper side view which shows the state visually recognized from the upper direction (arrow A direction) of FIG. The graph showing the sensitivity characteristic which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Angular velocity sensor, 10 ... Piezoelectric vibration piece, 20 ... Base part, 40, 50 ... Drive arm, 60 ... Detection arm, 61, 62 ... Detection arm part, 63, 64 ... Weight part.

Claims (8)

A base, a drive arm extending in parallel to the Y axis from the base or a connecting arm connected to the base, and bending-vibrating in the X-axis direction perpendicular to the Y axis; and a detection arm parallel to the drive arm; A piezoelectric vibrating piece formed on the XY plane,
Detecting means for outputting a detection signal of the Y-axis rotation system in accordance with a vibration component generated in the detection arm due to the Coriolis force in the Z-axis direction given by rotation around the Y-axis;
An angular velocity sensor comprising: The angular velocity sensor according to claim 1,
The piezoelectric vibrating piece includes a first detection arm extending from the base in the Y-axis direction, a second detection arm extending in the negative Y-axis direction, and a first extending from the base in the X-axis direction. A connecting arm, a second connecting arm extending in the minus X-axis direction from the base, a driving arm connected to the first connecting arm and extending in the Y-axis direction and the minus Y-axis direction, An angular velocity sensor comprising: a drive arm connected to the second connection arm and extending in the Y-axis direction and the minus Y-axis direction. The angular velocity sensor according to claim 1 or 2,
An angular velocity sensor characterized in that a vibration component generated in the first detection arm and the second detection arm by a Coriolis force in the Z-axis direction given by the rotation about the Y-axis is a torsional vibration component. The angular velocity sensor according to claim 3.
The torsional vibration generated by the Coriolis force in the Z-axis direction given by the rotation about the Y-axis is viewed from the base, and the torsional vibration direction of the first detection arm and the torsional vibration direction of the second detection arm Is an opposite direction and each vibration amplitude is substantially the same. The angular velocity sensor according to any one of claims 1 to 4,
A weight portion is formed at the tip of each of the drive arm and the detection arm,
The angular velocity sensor, wherein the width D of the weight portion of the detection arm is set in a range of 5d ≦ D ≦ 10d with respect to the width d of the detection arm portion of the detection arm. The angular velocity sensor according to any one of claims 1 to 5,
An angular velocity sensor, wherein the detection sensitivity of the torsional vibration component of the Y-axis rotation system is adjusted by the detected detuning frequency of the first detection arm and the second detection arm. The angular velocity sensor according to claim 6.
The angular velocity sensor according to claim 1, wherein the adjustment of the detected detuning frequency is performed by increasing or decreasing the mass of a weight portion provided at the tip of each of the first detection arm and the second detection arm. The angular velocity sensor according to claim 6 or 7,
An angular velocity sensor characterized in that mass increase / decrease of the weight portion is performed from the width direction end portion toward the center of the weight portion.

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