JPH10246638A - Piezoelectric oscillation gyro - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a small-sized and thin piezoelectric oscillation gyro that can be connected without the need of input and output terminals and lead wires, restrains the oscillation of gyro characteristics with a simple structure and can be manufactured readily. SOLUTION: The gyro is formed such that a piezoelectric oscillator 200 with a plurality of electrodes including driving and detecting ones formed on one main surface of a piezoelectric plate 10 is arranged on a circuit substrate 300 including a circuit block 32 being a driving and detecting circuit. Electrodes of the piezoelectric oscillator 200 respectively include a leader electrode extended to the side face of the piezoelectric plate 10, and the circuit block 32 of the circuit substrate 300 includes a plurality of connecting conductors extended toward an attachment position of the piezoelectric oscillator 200, and further, the connecting conductor and leader electrode are conductivity connected to each other as the piezoelectric oscillator 200 is set on the circuit substrate 300, and the piezoelectric oscillator 200 is put on the circuit substrate 300 by adhesively forming the nearby portion around a cavity 30 of the circuit substrate 300.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to a gyroscope mainly used for an automobile navigation system, an attitude control system, a camera-shake correction angular velocity sensor of a camera-integrated VTR camera, and a piezoelectric device utilizing ultrasonic vibration. The present invention relates to a vibrating gyroscope, and more particularly, to a piezoelectric vibrating gyroscope using an energy trapping vibration mode as a vibration mode.

[0002]

2. Description of the Related Art In general, a piezoelectric vibrating gyroscope belongs to a gyroscope utilizing a mechanical phenomenon that, when a rotational angular velocity is applied to a vibrating object, a Coriolis force is generated in a direction perpendicular to the vibration direction.

In this gyroscope, in a composite vibration system configured to be able to excite vibrations in two different directions orthogonal to each other, the vibrator itself is parallel to a line where two vibration planes intersect with one vibration being excited. When rotated about an axis, a force acts in a direction perpendicular to this vibration by the action of the Coriolis force described above, and the other vibration is excited. Since the magnitude of this vibration is proportional to the amplitude of the vibration on the input side and the rotational angular velocity, when the vibration amplitude on the input side is fixed,
The magnitude of the applied angular velocity can be determined from the magnitude of the output voltage.

FIG. 6 is a perspective view showing a basic structure of a conventional piezoelectric vibrator 100 for a piezoelectric vibrating gyroscope. This piezoelectric vibrator 100 has a metal prism 10 having a square cross-sectional shape.
The piezoelectric ceramic thin plate 1 is located almost at the center of the adjacent surfaces
02 and 103 are joined to form a piezoelectric ceramic thin plate 103.
Is locally grounded. The piezoelectric ceramic thin plates 102 and 103 have electrodes formed on both surfaces thereof and are polarized in the thickness direction, and lead wires 104 and 10 for drawing out are provided on one surface (front surface).
5 is connected.

It is known that the metal prism 101 has two bending vibration modes that are orthogonal to each other, and that the resonance frequencies of the two bending vibration modes are substantially equal when the characteristics of the material are uniform. Therefore, when a voltage having a frequency substantially equal to the resonance frequency of the bending vibration of the metal prism 101 is applied to the piezoelectric ceramic thin plate 102, the surface where the piezoelectric ceramic thin plate 102 is bonded becomes uneven (Y-axis direction).
Bending vibration. In this state, when the metal prism 101 is rotated around an axis (Z axis) parallel to the length direction (the Ω direction in the figure), the metal prism 101 is a surface on which the piezoelectric ceramic thin plate 103 is joined by the action of Coriolis force. Also bends and vibrates in the direction in which the surface becomes uneven (X-axis direction), and a voltage is generated in the piezoelectric ceramic thin plate 103 by such a piezoelectric effect.

Since the magnitude of the voltage generated here is proportional to the magnitude of the vibration excited by the piezoelectric ceramic thin plate 102 and the magnitude of the applied rotational angular velocity, the magnitude of the excitation voltage applied to the piezoelectric ceramic thin plate 102 Is constant, the voltage generated in the piezoelectric ceramic thin plate 103 is a voltage proportional to the rotational angular velocity of the metal prism 101.

[0007] By the way, an intermediate frequency filter of an FM radio or a television uses an oscillator having a structure utilizing an energy trapping thickness-shear vibration mode (hereinafter, simply referred to as an energy trapping oscillator).

FIG. 7 shows a basic configuration of an example of a conventional energy trap type vibrator, in which FIG. 7A is related to a plan view and FIG. 7B is related to a cross-sectional view. It is. Here, the energy confined vibration refers to a vibration mode in which the energy of the vibration is concentrated in the vicinity of the driving electrode. This includes longitudinal vibration and sliding vibration in the thickness direction of the piezoelectric plate 10 as well as piezoelectric vibration. There are many things such as longitudinal vibration and sliding vibration of a rectangular plate.

Referring to FIGS. 7 (a) and 7 (b), the energy trapped vibration is, for example, 6 mm long as shown in FIG. 7 (a) because the energy of the vibration is concentrated near the drive electrode. By using a piezoelectric plate (piezoelectric ceramic plate) 10 having a width of 6 mm and a thickness of 0.2 mm, drive electrodes 51 and 52 are formed in a 1.5 mm diameter region substantially at the center of one main surface, and the other main plate is formed. The drive electrode 53 is formed in a region extending from a portion facing the drive electrodes 51 and 52 on the
It is assumed that a 10.7 MHz ceramic filter (energy trap type vibrator) for radio is obtained.

The support structure of the energy trap type vibrator in this case is, as shown in FIG.
Assuming that cavities 54 are formed on both sides of a region having a diameter of about 3 mm centering on
Should be fixed with. Such a structure hardly affects the characteristics of the vibrator. That is, in the case of this energy trap type vibrator, a lead terminal can be freely formed, and a filter which is not affected by the support structure can be obtained.

In general, when an energy trapping type vibrator according to another simple example is formed, as shown in FIG. 9, a piezoelectric plate (piezoelectric ceramic plate) 10 is supported using a support 56 and a circuit is formed. Mounted on board.

[0012]

In the above-described piezoelectric vibrator for a piezoelectric vibrating gyroscope, since the bending vibration mode of the metal prism is used, the piezoelectric vibrator must be supported and fixed at the position of the vibration node. This operation is complicated, and when connecting the drive / detection circuit and the electrode of the piezoelectric vibrator with a lead wire in the manufacturing process of assembling the piezoelectric vibrating gyroscope,
Gyro characteristics will vary if the connection state varies, so connections must be made with precision to suppress the variation.However, such connection work is difficult, and a drive and detection circuit has been deployed. Since the piezoelectric vibrator supported by the holder is mounted on the substrate for assembly, there is a problem that it is difficult to form a small and thin piezoelectric vibrating gyroscope.

On the other hand, in the case of the energy trap type vibrator shown in FIGS. 7A and 7B, such a problem is solved, and the input / output terminals can be connected without using lead wires. It is possible, and it is presumed that it will be easy to configure a piezoelectric vibrating gyroscope by combining a piezoelectric vibrator on a substrate on which a drive / detection circuit is provided, but the vibrator here is structurally arranged such as electrodes. Is not applicable to the piezoelectric vibrating gyroscope as it is.

In the case of the energy trap type vibrator shown in FIG. 9, the piezoelectric plate is supported by using a support and mounted on a circuit board. When applied to a piezoelectric vibrating gyroscope, there is a problem that the gyroscope characteristics tend to vary.

The present invention has been made in order to solve such a problem, and its technical problem is that the input / output terminals can be connected without using lead wires, and the gyro characteristic can be obtained with a simple configuration. It is an object of the present invention to provide a small and thin energy trap type piezoelectric vibrating gyroscope that can be easily manufactured by suppressing variations in the size.

[0016]

According to the present invention, there is provided a piezoelectric vibrator utilizing energy-confined thickness-shear vibration in which a plurality of electrodes for driving and detecting are formed on at least one main surface of a piezoelectric plate. In a piezoelectric vibrating gyroscope having a driving / detecting circuit for the piezoelectric vibrator and a circuit board for disposing the piezoelectric vibrator at a predetermined position, the plurality of electrodes extend to the side surface of the piezoelectric plate. The driving / detecting circuit includes a drawn-out electrode, the driving / detecting circuit includes a drawn-out connection conductor extending toward a predetermined position, and the drawing-out electrode and the connection conductor are formed at a predetermined position on the circuit board of the piezoelectric vibrator. The piezoelectric vibrating gyroscopes which are conductively connected to each other at the time of deployment are obtained.

Further, according to the present invention, in the above piezoelectric vibrating gyroscope, the circuit board has a hollow portion at a portion corresponding to substantially the center of the piezoelectric plate at a predetermined location, and the piezoelectric vibrator is located near the periphery of the hollow portion. To form a piezoelectric vibrating gyroscope provided on a circuit board.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A piezoelectric vibrating gyroscope according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing the basic configuration of a piezoelectric vibrator 200 for an energy trap type piezoelectric vibrating gyroscope according to one embodiment of the present invention.

The piezoelectric vibrator 200 has a plurality (three in this case) of electrodes 11, 12 including driving and detecting electrodes on at least one main surface of a piezoelectric plate (piezoelectric ceramic plate) 10.
The electrodes 13, 13, and 13 include extraction electrodes 11 a, 12 a, and 13 a, which extend and extend on the side surfaces of the piezoelectric plate 10, respectively. I have.

More specifically, the piezoelectric vibrator 200 has a first position at each vertex forming an isosceles triangle approximately at the center of one main surface of the piezoelectric plate 10 having a polarization axis in the thickness direction. Electrode 11, a second electrode 12, and a third electrode 13 are formed, and the second electrode 12, the third electrode 1,
The third electrode 11 and the first electrode 11 are arranged so as to face each other in parallel, and are arranged so that vibration in the X direction can be excited. Electrodes 11a, 1 for extracting electrodes 11, 12, 13
Since 2a and 13a are drawn out to the side of the piezoelectric plate 10, the edge of the piezoelectric vibrator 200 is fixed to the support at a position symmetrical in the X direction. Incidentally, the electrode 11 is used for driving, and the electrodes 12 and 13 are used for detection.

FIG. 2 is a block diagram showing a basic configuration of a detection / drive circuit applied (connected) to the piezoelectric vibrator 200.

In this detecting / driving circuit, current detecting circuits 18 and 19 are connected to the electrodes 12 and 13, respectively.
The differential amplifier circuit 22 is provided on the output side of the current detection circuits 18 and 19.
Is connected, and the output from the differential amplifier circuit 22 becomes a detection signal of the piezoelectric vibration gyro via the synchronous detection circuit 23 and the rectification circuit 24.

On the other hand, the current detection circuits 18 and 19 are connected to an oscillation circuit 25 for satisfying self-excited oscillation conditions, and the oscillation circuit 25 is connected to the electrode 11 via a drive circuit 26 for performing X vibration. This constitutes a self-excited oscillation circuit. This self-excited oscillation circuit makes the piezoelectric vibrator 20
An AC voltage having a frequency substantially equal to the resonance frequency of the thickness slip vibration of 0 is applied to the electrode 11.

Next, the driving principle of the piezoelectric vibrator 200 will be specifically described with reference to FIGS. 3 (a) and 3 (b). FIG. 3 shows the basic structure of a parallel electric field excitation type thickness-slip energy trapping type piezoelectric vibrator when the piezoelectric vibrator 200 is simplified, and FIG. 3 (a) relates to a plan view thereof. FIG. 2B relates to a side sectional view of a main part (electrodes show only local parts).

In this energy trap type piezoelectric vibrator, the partial electrodes 14, 1 opposed in the X-axis direction on the same plane at the center of the piezoelectric plate 10 polarized in the thickness direction (Z-axis direction).
5 is formed, and an electric field in a direction substantially parallel to the surface of the plate (X-axis direction) is applied to a portion sandwiched between the partial electrodes 14 and 15. Therefore, the interaction between the electric field here and the polarization in the thickness direction orthogonal to the electric field causes the partial electrodes 14,
By properly designing the dimensions of 15 according to the characteristics of the piezoelectric material to be used, it is possible to obtain a parallel electric field excitation type thickness-slip energy trapped vibration in a portion sandwiched between the partial electrodes 14 and 15. Incidentally, the thickness-shear vibration here indicates vibration in which the direction of displacement is parallel to the plate surface and the direction of wave propagation is the thickness direction of the plate.

In the case of the piezoelectric vibrator 200 shown in FIG. 1, the electrode 11 is positioned at the apex of an isosceles triangle and the electrode 1
2 and 13 are respectively located at the base angles of an isosceles triangle, and the electrodes 11 and 12 and 13 are arranged so as to be parallel, and the electrodes 12 and 13 have current detection circuits 18 and 19 each having a virtual ground function. It is connected to the. This allows
Since the electrodes 12 and 13 are virtually maintained at the reference potential by the virtual ground function of the current detection circuits 18 and 19, they can be regarded as potential ground terminals.

Therefore, when a drive voltage for excitation having a frequency substantially equal to the resonance frequency of the thickness-slip mode of the piezoelectric plate 10 is applied to the electrode 11, the center of the electrode 11 and the electrode 12 , 13 in the direction of the straight line connecting the midpoints of the straight lines connecting the centers of the straight lines connecting the centers of the energy generating vibration modes. In this state, the piezoelectric plate 1
When 0 is rotated about an axis orthogonal to its main surface, the action of Coriolis force causes thickness-shear vibration in a direction perpendicular to the direction of the excited thickness-shear vibration. The thickness slip vibration generated by this Coriolis force causes the electrodes 11, 1
2 and the impedance between the electrodes 11 and 13 change, and as a result, the current value flowing into the current detection circuits 18 and 19 changes. As described above, since the electrodes 12 and 13 are arranged symmetrically with respect to the direction of the excited thickness-shear vibration, the currents that change due to the Coriolis force have the same amplitude, and also have currents 180 degrees out of phase with each other. Becomes As a result, the output voltages of the current detection circuits 18 and 19 also become voltages having phases different from each other by 180 degrees, the difference value between these output voltages is detected by the differential circuit 22, and the difference detection voltage is determined by the synchronous detection circuit 23. The synchronous detection is performed at the timing described above, and the output is rectified by the rectifier circuit 24, so that a DC output voltage proportional to the applied rotational angular velocity can be obtained.

On the other hand, the current detection circuits 18 and 19 are connected to the electrode 11 via an oscillation circuit 25 and a drive circuit 26 for satisfying the self-excited oscillation condition, and constitute a self-excited oscillation loop. The resonator can be efficiently driven by automatically tracking the resonance frequency of the resonator 200. Therefore, high-sensitivity gyro characteristics can be obtained.

The detection / driving circuit having each circuit shown in FIG. 2 is provided on a circuit board as a circuit block.

FIG. 4 is an exploded perspective view shown for explaining the arrangement of the piezoelectric vibrator 200 on the circuit board 300. As shown in FIG. The circuit board 300 has a circuit block 32 as a drive / detection circuit for the piezoelectric vibrator 200, and the piezoelectric vibrator 200 is arranged at a predetermined position. The circuit block 32 includes a plurality (three in this case) of connection conductors 31a, 31b, 3 which are extended toward a predetermined position (the position where the piezoelectric vibrator 200 is attached) and drawn out.
1c, and these connecting conductors 31a, 31
When the piezoelectric vibrator 200 is disposed at a predetermined position on the circuit board 300, the electrodes 11, 12, 13
Are electrically connected to each of the lead-out electrodes 11a, 12a, and 13a on a one-to-one basis.

The circuit board 300 is provided with a hollow portion 30 at a position corresponding to substantially the center of the piezoelectric plate 10 at a predetermined position. It is arranged on a substrate 300. The cavity 30 is provided on the circuit board 300 side so that the vibrating part of the piezoelectric plate 10 does not touch due to the principle of the energy trap type vibrating gyroscope. However, here, the fixed formation in the vicinity of the periphery of the hollow portion 30 is performed by the extraction electrode 1 drawn out to the side surface of the piezoelectric plate 10.
Connection conductor 3 between 1a, 12a, 13a and circuit board 300
This is performed after the electrical connection with 1a, 31b, 31c is made. As a result, the piezoelectric vibrator 200 (piezoelectric plate 10) and the circuit block 32 are electrically connected via the connection conductor 31.

Incidentally, FIG. 5 shows the form of the fixed portion 33 on the circuit board 300 according to this arrangement by diagonal lines. The fixed portion 33 fixes the piezoelectric plate 10 to the circuit board 300 as shown. In this case, it is sufficient to form the piezoelectric plate 10 near the periphery of the piezoelectric plate 10 without leakage.

[0034]

As described above, according to the piezoelectric vibrating gyroscope of the present invention, the plurality of electrodes of the piezoelectric plate of the piezoelectric vibrator are provided with the lead-out electrodes extending to the side surfaces of the piezoelectric plate, respectively. The circuit block, which is the drive / detection circuit, has a plurality of connection conductors extending toward the mounting position of the piezoelectric vibrator. When the piezoelectric vibrator (piezoelectric plate) is disposed on the circuit board, the connection conductor is provided. The lead-out electrodes are electrically connected to each other in a one-to-one manner, and a cavity is formed in the mounting position of the piezoelectric vibrator on the circuit board, and the piezoelectric vibrator is fixedly formed in the vicinity of the cavity of the circuit board. Since it is arranged on the circuit board, the input / output terminals can be connected without using lead wires. Shaped Energy-trap type piezoelectric vibrating gyro can be obtained. In particular, since the piezoelectric vibrator is directly fixed to the circuit board, the piezoelectric vibrator can be easily mounted, and assembling and manufacturing are simplified. Since the impact strength is improved and the use of a support is not required, the structure is simple and the support is easy, and as a result, cost reduction and size reduction can be sufficiently achieved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a basic configuration of a piezoelectric vibrator for an energy trap type piezoelectric vibrating gyroscope according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a drive / detection circuit applied to the piezoelectric vibrator for the piezoelectric vibrating gyroscope shown in FIG.

FIG. 3 shows the basic structure of a parallel electric field excitation type thickness-slip energy trapping type piezoelectric vibrator when the piezoelectric vibrator for the piezoelectric vibrating gyroscope shown in FIG. 1 is simplified, and (a)
Fig. 1B relates to a plan view thereof, and Fig. 2B relates to a side sectional view of a main portion thereof (electrodes show only local portions).

FIG. 4 is an exploded perspective view shown for explaining the arrangement of the piezoelectric vibrator for a piezoelectric vibrating gyroscope shown in FIG. 1 on a circuit board.

5 is a perspective view showing a fixed portion on a circuit board by the arrangement shown in FIG. 4;

FIG. 6 is a perspective view showing a basic configuration of a conventional piezoelectric vibrator for a piezoelectric vibrating gyroscope.

7A and 7B show a basic configuration according to an example of a conventional energy trap type vibrator, in which FIG. 7A relates to a plan view and FIG. 7B relates to a cross-sectional view thereof.

8 is a side view showing a support structure of the energy trap type vibrator shown in FIG.

FIG. 9 is a perspective view showing a support structure according to another example of the conventional energy trap type vibrator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Piezoelectric plate 11, 12, 13 Electrode 11a, 12a, 13a Leading electrode 14, 15 Partial electrode 18, 19 Current detection circuit 22 Differential circuit 23 Synchronous detection circuit 24 Rectifier circuit 25 Oscillation circuit 26 Drive circuit 30 Hollow part 31a, 31b, 31c Connection conductor 32 Circuit block 33 Fixed part 51, 52, 53 Drive electrode 56 Support 100, 200 Piezoelectric vibrator 101 Metal prism 102, 103 Piezoelectric ceramic thin plate 104, 105 Lead wire 300 Circuit board

Claims (2)

[Claims] 1. A piezoelectric vibrator utilizing energy-confined thickness-shear vibration in which a plurality of electrodes for driving and detecting are formed on at least one main surface of a piezoelectric plate, and for driving and detecting the piezoelectric vibrator. In a piezoelectric vibrating gyroscope having a circuit and a circuit board for disposing the piezoelectric vibrator at a predetermined position, the plurality of electrodes extend from a side surface of the piezoelectric plate and are drawn out. Wherein the drive / detection circuit includes a connection conductor extending toward the predetermined location and being drawn out, and the lead-out electrode and the connection conductor are provided at the predetermined location on the circuit board of the piezoelectric vibrator. A piezoelectric vibrating gyroscope, wherein the piezoelectric vibrating gyroscopes are electrically connected to each other in a one-to-one manner when the piezoelectric vibrating gyroscope is arranged. 2. The piezoelectric vibrating gyroscope according to claim 1, wherein the circuit board has a hollow portion at a portion corresponding to substantially the center of the piezoelectric plate at the predetermined location, and the piezoelectric vibrator is formed at the hollow portion. A piezoelectric vibrating gyroscope, wherein the vibrating gyroscope is provided on the circuit board with the vicinity thereof being fixedly formed.