JP2001194147A - Piezoelectric vibrating gyro - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibrating gyro having a good vibration characteristic such that it can suppress axial displacement of a vibrating direction without mechanical machining to a piezoelectric vibrator. SOLUTION: In the piezoelectric vibrator, six electrode strips are formed as electrode patterns in six equally spaced positions on the circumference of the outer peripheral surface of a columnar piezoelectric ceramics extending in the direction of one axis, the positions being parallel to the one axis (longitudinal axis) of the columnar piezoelectric ceramics. The electrode pattern of a drive part made up of a driving electrode 13 and common ground electrode 12 and 14 adjacent to the driving electrode and the electrode pattern of a detecting part made up of a detecting electrode 15 and common ground electrodes 14 and 16 adjacent to the detecting electrode are made different in shape by cutting away approximately the center portion of the common ground electrode 16 in the direction of the one axis. This provides an appropriate difference in resonant frequency between the drive part and the detecting part, thus providing a good vibration characteristic.

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 in an automobile navigation system or a camera shake correction device of a camera-integrated VTR and the like, and a piezoelectric device using a rod-shaped bending vibrator made of a piezoelectric material. Related to a vibrating gyro.

[0002]

2. Description of the Related Art Conventionally, a piezoelectric vibrating gyroscope of this type is known as a gyroscope utilizing a mechanical phenomenon in which when a rotating object is given a rotational angular velocity, a Coriolis force is generated in a direction perpendicular to the vibration direction. Have been.

In general, a piezoelectric vibrating gyroscope is a composite vibrating system configured to be able to excite and detect two different directions orthogonal to each other, and to excite the piezoelectric vibrator itself in a state where one vibration is excited. When the rotation is made about an axis parallel to the line where the two vibration surfaces intersect, a force acts in a direction perpendicular to the vibration by the action of the above-mentioned Coriolis force, and the other vibration is newly excited in that direction. Since the magnitude of this new vibration is proportional to the magnitude of the vibration on the input side and the rotational angular velocity applied to the piezoelectric vibrator, when the input voltage is constant, the magnitude of the rotational angular velocity is calculated from the magnitude of the output voltage. Can be requested. By the way, when the electrode pattern is formed on the piezoelectric vibrator, the magnitude of the vibration on the input side indicates the amplitude of the driving vibration generated by the driving voltage as the input voltage applied to the driving electrode of the piezoelectric vibrator, and The voltage is a detection voltage obtained from the detection electrode of the piezoelectric vibrator.

FIG. 5 is a perspective view showing an external structure of a piezoelectric vibrator 100 used in a conventional piezoelectric vibrating gyroscope. FIG. 6 is a plan view showing an expanded electrode pattern of the piezoelectric vibrator 100.

The piezoelectric vibrator 100 is located at a position on the outer peripheral surface of the columnar piezoelectric ceramics 51 extending in one axis direction, which divides the circumference into six equal parts, and in one axial direction (length direction) of the columnar piezoelectric ceramics 51. After forming six strip-shaped electrodes as electrode patterns at positions parallel to (1), these strip-shaped electrodes are alternately connected to each other and subjected to a polarization process as two terminals, whereby one axis direction of the columnar piezoelectric ceramics 51 is formed. , Three common ground electrodes 52, 54, 54.
56 and a common ground electrode 52, 54
One drive electrode 53, one detection electrode 55 disposed between the common ground electrodes 54 and 56, and a common ground electrode 56.
, And one detection electrode 57 arranged at a position substantially symmetrical with the detection electrode 55.

In this piezoelectric vibrator 100, the six band-shaped electrodes forming each electrode are equally divided into six in the circumferential direction of the columnar piezoelectric ceramics 51, and at the same time in the axial direction of the columnar piezoelectric ceramics 51. Since they are arranged in the same length, the polarization state becomes uniform when polarization is applied.
That is, in the piezoelectric vibrator 100, the sound velocity becomes uniform due to the uniform polarization state, and the resonance frequency in the driving direction and the resonance frequency in the detection direction become substantially the same.

[0007]

The above-described piezoelectric vibrator has a configuration in which the polarization state is theoretically uniform and the speed of sound is uniform. However, in actuality, a cylindrical piezoelectric ceramic material or an electrode pattern is used. In addition to the variations in the accuracy of the shape and the dimensions, or the variations in the polarization state, etc., the sound velocity becomes slightly non-uniform.
There is a difference between the resonance frequency in the driving direction and the resonance frequency in the detection direction, which should be the same. In such a case, when the piezoelectric vibrator is excited, an axial displacement occurs in the vibration direction (however, conversely, the difference between the resonance frequency in the X direction which is the driving direction and the resonance frequency in the Y direction which is the detection direction is about 50 Hz or more. If it does, axial displacement will not occur and good characteristics as a piezoelectric vibrator will be obtained), and the output and phase of the two detection outputs will differ even in a stationary state.

[0008] Therefore, in the finishing stage at the time of actual production of the piezoelectric vibrator, in order to suppress the difference in resonance frequency, mechanical processing is applied to the piezoelectric vibrator to perform finishing processing such as adjusting the resonance frequency. I have.

However, such a finishing process involves mechanical processing of the piezoelectric vibrator and deteriorates the appearance quality of a finished product, which is not preferable.

The present invention has been made to solve such a problem, and a technical problem of the present invention is to minimize the occurrence of axial displacement in the vibration direction without applying mechanical processing to the piezoelectric vibrator. An object of the present invention is to provide a piezoelectric vibrating gyroscope having excellent vibration characteristics.

[0011]

According to the present invention, a position on the outer peripheral surface of a columnar piezoelectric body extending in a uniaxial direction is a position equally dividing the circumference, and the columnar piezoelectric body is positioned in the uniaxial direction. A plurality of band-shaped electrodes formed as electrode patterns at positions parallel to the plurality of common ground electrodes connected circumferentially to each other on the end side of the columnar piezoelectric body in the uniaxial direction; and a plurality of common grounds. A piezoelectric vibrator for a piezoelectric vibratory gyroscope including a drive electrode disposed between a pair of electrodes and a detection electrode disposed between another pair of a plurality of common ground electrodes. In the above, the electrode pattern of the drive unit composed of the drive electrode and the common ground electrode adjacent to the drive electrode, and the electrode pattern of the detection unit composed of the detection electrode and the common ground electrode adjacent to the detection electrode And form By different, piezoelectric vibrator piezoelectric vibrating gyroscope the resonant frequency of the resonant frequency and the detection portion of the drive unit has a difference is obtained.

Further, according to the present invention, in the piezoelectric vibrator for a piezoelectric vibrating gyroscope, the plurality of strip-shaped electrodes have the same length in the uniaxial direction as the detection electrodes, and the plurality of common ground electrodes are specific. Thus, a piezoelectric vibrator for a piezoelectric vibrating gyroscope including another detection electrode arranged at a position substantially linearly symmetric with the detection electrode with respect to is obtained.

Further, according to the present invention, in the piezoelectric vibrator for a piezoelectric vibrating gyroscope, the length of the detecting electrode and the other detecting electrodes in one axial direction is shorter than the length of the driving electrode in the one axial direction. Piezoelectric vibrator is obtained.

In addition, according to the present invention, in any one of the piezoelectric vibrators for a piezoelectric vibrating gyroscope, the drive electrode, the detection electrode, the other detection electrodes, and the plurality of common ground electrodes are formed by the vibration of the columnar piezoelectric body. A piezoelectric vibrator for a piezoelectric vibrating gyroscope is obtained which is formed near a node and has one electrical connection point for electrically connecting to an external electrical circuit.

On the other hand, according to the present invention, in the piezoelectric vibrator for a piezoelectric vibrating gyroscope, the detecting electrode and the other detecting electrodes are arranged so as to include symmetrical apexes in the circumferential direction of the cylindrical piezoelectric body. A piezoelectric vibrator for a piezoelectric vibrating gyroscope having a local portion extending along the direction and forming an electrical connection point at a vertex position symmetrical in the circumferential direction of the local portion is obtained.

On the other hand, according to the present invention, there is provided a piezoelectric vibrating gyroscope using any one of the above piezoelectric vibrating gyroscope piezoelectric vibrators, including an external electric circuit and using an electric connection point. Thus, a piezoelectric vibrating gyroscope having both mechanical support and electrical connection by a conductive member can be obtained.

[0017]

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 an exploded plan view showing an electrode pattern formed on a piezoelectric vibrator for a piezoelectric vibrating gyroscope according to an embodiment of the present invention. Also in the case of the piezoelectric vibrator here, as compared with the conventional electrode pattern shown in FIG. 6, the position on the outer peripheral surface of the columnar piezoelectric ceramic extending in the uniaxial direction is a position that divides the circumference into six equal parts, and After forming six band-shaped electrodes as electrode patterns at positions parallel to the uniaxial direction (length direction) of the columnar piezoelectric ceramics, these band-shaped electrodes are alternately connected to each other and subjected to polarization processing as two terminals. As a result, the three common ground electrodes 12, 14, 16 connected to each other along the circumferential direction at the ends (here, both ends) in the uniaxial direction of the columnar piezoelectric ceramics
, One drive electrode 13 disposed between the common ground electrodes 12 and 14, one detection electrode 15 disposed between the common ground electrodes 14 and 16, and detection with the common ground electrode 16 interposed therebetween. The point that the electrode 15 and one detection electrode 17 arranged at a position substantially symmetrical with the line are configured in the same basic configuration.

However, the shape of the electrode pattern here, that is, the shape of the electrode pattern of the drive section composed of the drive electrode 13 and the common ground electrodes 12 and 14 adjacent to the drive electrode 13, the detection electrode 15 and the The shape of the electrode pattern of the detection unit composed of the common ground electrodes 14 and 16 adjacent to the detection electrode 15 is different from that of the common ground electrode 16 because the substantially central portion in the axial direction of the common ground electrode 16 is omitted. The resonance frequency of the drive unit and the resonance frequency of the detection unit have a difference.

That is, in this piezoelectric vibrator, even if the six band-shaped electrodes forming each electrode are formed at positions equally divided into six in the circumferential direction of the columnar piezoelectric ceramic, one axis of the columnar piezoelectric ceramic is formed. Common ground electrode 1 in the length in the direction
6 is shorter than the other common ground electrodes 12 and 14, the polarization state becomes non-uniform when polarized by such an electrode pattern.

FIG. 2 is a sectional view on a plane parallel to an end face of the piezoelectric vibrator for a piezoelectric vibrating gyroscope described above. Here, in the piezoelectric vibrator, the drive electrode 13 is disposed on the upper surface, the common ground electrode 16 is positioned on the lower surface, the direction connecting the drive electrode 13 and the common ground electrode 16 is defined as the X direction of the drive direction, and the Y direction is orthogonal to the drive direction. When the direction is the detection direction, the lower polarization state is weaker than the upper polarization state of the piezoelectric vibrator, that is, the polarization state in the X direction of the piezoelectric vibrator is weaker than the polarization state in the Y direction. As a result, the sound speed in the X direction becomes faster than the sound speed in the Y direction. As a result, when replaced by the resonance frequency, the resonance frequency in the X direction is higher than the resonance frequency in the Y direction, and the resonance frequency in the X direction becomes higher. This indicates that there is a difference from the resonance frequency in the Y direction.

The electrode pattern of the piezoelectric vibrator shown in FIG. 1 is modified so that, for example, the common ground electrode 16 has the same length as the other common ground electrodes 12 and 14, and the lengths of the detection electrodes 15 and 17 are reduced. Similarly, if the length of the common ground electrodes 12 and 14 facing the drive electrode 13 is changed to be shorter without changing the length of the common ground electrode 16, the length of the drive electrode 13 may be reduced. The effect is obtained that there is a difference between the resonance frequency in the Y direction and the resonance frequency in the Y direction. Generally, such a difference in the resonance frequency changes depending on the length of the electrode to be shortened, and the difference is determined by the ratio of the length to the other electrodes.

FIG. 3 shows another common ground electrode 12 facing the drive electrode 13 without changing the length of the common ground electrode 16.
The relationship between the resonance frequency difference (Hz) in the X direction on the drive side and the Y direction in the detection side with respect to the ratio (%) of the lengths of the other common ground electrodes 12 and 14 when the length of the 14 is changed to be short. It is. However, here, the resonance frequency in the drive-side X direction is 26 kHz, and the other common ground electrodes 12 and 14
When the length is the same as the length of the common ground electrode 16, the ratio of the lengths of the other common ground electrodes 12 and 14 is set to 100%.

Here, the other common ground electrodes 12 and 14
If the length ratio is set to about 70% or less of the length of the common ground electrode 16, the resonance frequency difference can be reduced to 50 Hz or less. Such a resonance frequency difference of 50H
In the case of a piezoelectric vibrator of z or less, the occurrence of axial displacement in the vibration direction can be suppressed as much as possible without applying mechanical processing to the piezoelectric vibrator, and the piezoelectric vibrator has good vibration characteristics.

FIG. 4 is an expanded plan view showing an electrode pattern formed on a piezoelectric vibrator for a piezoelectric vibrating gyroscope according to another embodiment of the present invention.

Also in the case of the piezoelectric vibrator here, the position on the outer peripheral surface of the columnar piezoelectric ceramics extending in one axis direction is divided into six equal parts as compared with the conventional electrode pattern shown in FIG. After forming six strip electrodes as electrode patterns at positions parallel to one axis direction (length direction) of the columnar piezoelectric ceramics, these strip electrodes are connected to every other one and polarized as two terminals. , Three common ground electrodes 32, 34, 36 connected to each other along the circumferential direction on one axial end side (here, one end side) of the columnar piezoelectric ceramics; One drive electrode 13 disposed between
And one detection electrode 35 disposed between the common ground electrodes 34 and 36, and one detection electrode 3 disposed at a position substantially in line with the detection electrode 35 across the common ground electrode 36.
7 is the same as the basic configuration.

However, the shape of the electrode pattern here, that is, the shape of the electrode pattern of the drive section composed of the drive electrode 13 and the common ground electrodes 32 and 34 adjacent to the drive electrode 13, and the shape of the detection electrode 35 and the The shape of the electrode pattern of the detection unit composed of the common ground electrodes 34 and 36 adjacent to the detection electrode 35 differs from that of the common ground electrode 36 because substantially half of the common earth electrode 36 near the detection electrode 37 in one axial direction is missing. Furthermore, the detection electrodes 35 and 37 have local portions extending along the circumferential direction so as to include the apex positions symmetrical in the circumferential direction of the columnar piezoelectric ceramics. Common earth electrode 32,
34 and 36 are located at vertices symmetrical in the circumferential direction of the columnar piezoelectric ceramics, and are formed at a total of four locations in the longitudinal direction, that is, two locations above and below the vibrating node, for a total of four locations. Electrical connection point 13 for electrical connection
a, 35a, 37a, and 36a (where the electrical connection points 35a and 37a of the detection electrodes 35 and 37 are formed at symmetrical top and bottom vertices in the local circumferential direction). The drive unit (drive side X
Direction) and the resonance frequency of the detection unit (Y direction on the detection side) have a difference.

Generally, when a piezoelectric vibrating gyroscope is manufactured using the piezoelectric vibrator having such a configuration, the piezoelectric vibrator is mechanically supported by a support member such as silicon rubber, and each electrode and the electric circuit are connected to a lead wire. In the piezoelectric vibrator here, each electrode is located at a vertex symmetrical in the circumferential direction of the piezoelectric vibrator, and is positioned at a vibration node in the length direction. Electrical connection points 13a, 35a, 3
7a and 36a, respectively, so that each of the electrical connection points 13a, 35a, 37a and 36a can be used to connect with an electric circuit by a conductive member such as a metal plate in the vertical and horizontal directions of the piezoelectric vibrator. The piezoelectric vibrating gyroscope can be easily manufactured by using both the electrical connection and the mechanical support of the piezoelectric vibrating gyroscope.

[0029]

As described above, according to the piezoelectric vibrating gyroscope of the present invention, the electrode pattern formed on the existing piezoelectric vibrating gyroscope piezoelectric vibrator (columnar piezoelectric body) is improved, and the driving electrodes and The shape of the electrode pattern of the drive unit composed of the one adjacent to the drive electrode of the common ground electrode and the electrode pattern of the detection unit composed of the one adjacent to the detection electrode and the detection electrode of the common ground electrode should be different. The resonance frequency of the drive unit (X direction on the drive side) and the detection unit (Y
Mode) (approx. 50Hz or more)
, So that good vibration characteristics can be obtained, so that the occurrence of axial displacement in the vibration direction can be suppressed as much as possible without applying mechanical processing to the piezoelectric vibrator. In another form of piezoelectric vibrator (cylindrical piezoelectric body), each electrode formed as an electrode pattern is located at a vertex symmetrical in the circumferential direction of the cylindrical piezoelectric body and located at a vibration node in the longitudinal direction. When a piezoelectric vibrating gyroscope is manufactured using a piezoelectric vibrator, the piezoelectric vibrating gyroscope is formed using a conductive member between the electric connecting point and an electric circuit. Since the piezoelectric vibrating gyroscope can be easily manufactured by using both the electrical connection and the mechanical support in the above, the piezoelectric vibrating gyroscope having excellent gyro characteristics can be mass-produced.

[Brief description of the drawings]

FIG. 1 is an exploded plan view showing an electrode pattern formed on a piezoelectric vibrator for a piezoelectric vibrating gyroscope according to an embodiment of the present invention.

FIG. 2 is a sectional view on a plane parallel to an end face of the piezoelectric vibrator for a piezoelectric vibrating gyroscope described in FIG.

FIG. 3 shows that the length of another common ground electrode facing the drive electrode is changed to be shorter without changing the length of a specific common ground electrode in the electrode pattern of the piezoelectric vibrator for the piezoelectric vibrating gyroscope described in FIG. 9 shows the relationship between the resonance frequency difference in the X direction on the drive side and the Y direction in the detection side with respect to the ratio of the length of another common ground electrode in the case.

FIG. 4 is an exploded plan view showing an electrode pattern formed on a piezoelectric vibrator for a piezoelectric vibrating gyroscope according to another embodiment of the present invention.

FIG. 5 is a perspective view showing an external configuration of a piezoelectric vibrator used in a conventional piezoelectric vibrating gyroscope.

6 is a developed plan view showing an electrode pattern of the piezoelectric vibrator shown in FIG. 5;

[Explanation of symbols]

12, 14, 16, 32, 34, 36, 52, 54, 5
6 Common ground electrode 13,53 Drive electrode 15,17,35,37,55,57 Detection electrode 13a, 35a, 36a, 37a Electrical connection point 51 Columnar piezoelectric ceramic 100 Piezoelectric vibrator

Claims (6)

[Claims] An electrode pattern is formed at a position on the outer peripheral surface of a columnar piezoelectric body extending in a uniaxial direction that divides the circumference equally, and at a position parallel to the uniaxial direction of the columnar piezoelectric body. A plurality of band-shaped electrodes, a plurality of common ground electrodes connected to each other along the circumferential direction on the end side of the columnar piezoelectric body in the uniaxial direction, and a pair of the plurality of common ground electrodes. A driving electrode disposed between the driving electrode and the common electrode, the piezoelectric vibrating gyroscope including a detection electrode disposed between another pair of the plurality of common ground electrodes. The shape of the electrode pattern of the drive unit formed of the ground electrode adjacent to the drive electrode and the shape of the electrode pattern of the detection unit formed of the detection electrode and the common ground electrode adjacent to the detection electrode are different. Strange Accordingly, the resonance frequency of the driving unit and the resonance frequency of the detection unit have a difference, thereby providing a piezoelectric vibrator for a piezoelectric vibrating gyroscope. 2. The piezoelectric vibrator for a piezoelectric vibrating gyroscope according to claim 1, wherein the plurality of strip-shaped electrodes have the same length in the uniaxial direction as the detection electrodes, and specify the plurality of common ground electrodes. A piezoelectric vibrator for a piezoelectric vibrating gyroscope, comprising: another detection electrode disposed at a position substantially symmetrical with the detection electrode with respect to the detection electrode. 3. The piezoelectric vibrator for a piezoelectric vibrating gyroscope according to claim 2, wherein the length of the detection electrode and the other detection electrode in the one axial direction is shorter than the length of the drive electrode in the one axial direction. A piezoelectric vibrator for a piezoelectric vibrating gyroscope, comprising: 4. The piezoelectric vibrator for a piezoelectric vibrating gyroscope according to claim 2, wherein the drive electrode, the detection electrode,
The other detection electrodes, and the plurality of common ground electrodes,
A piezoelectric vibrating gyroscope, which is formed in the vicinity of a vibration node of the columnar piezoelectric body and has one electrical connection point for electrically connecting to an external electric circuit. Piezoelectric vibrator. 5. The piezoelectric vibrator for a piezoelectric vibrating gyroscope according to claim 4, wherein the detection electrode and the other detection electrode include a symmetrical apex position in a circumferential direction of the columnar piezoelectric body. Having a local portion extending along the circumferential direction,
A piezoelectric vibrator for a piezoelectric vibrating gyroscope, wherein the electrical connection point is formed at a vertex position symmetrical in the circumferential direction of the local portion. 6. A piezoelectric vibrating gyroscope using the piezoelectric vibrator for a piezoelectric vibrating gyroscope according to claim 4 or 5, wherein the piezoelectric vibrating gyroscope includes the external electric circuit, and uses the electric connection point to connect to the electric circuit. A piezoelectric vibrating gyroscope characterized in that the piezoelectric vibrating gyroscope has a structure in which a conductive member serves both mechanical support and electrical connection.