JPH05264281A - Piezoelectric vibrating gyro - Google Patents

Abstract

PURPOSE:To provide a piezoelectric vibrating gyro which is simply structured, can be firmly supported with less influence on gyro characteristic by support and fixing, and is excellent in vibration resisting and shock resisting characteristics. CONSTITUTION:A piezoelectric vibrating gyro has two piezoelectric plates 15, 16 which have a driving electrode 19 and a detecting electrode 20 formed on one-side surfaces of the plate surfaces opposed to each other, respectively, and are polarized in the direction parallel to the plate surfaces (the direction shown by the arrow). The two piezoelectric plates 15, 16 are mutually connected 00 the other side of the plate surfaces so that the respective polarizing directions are crossed to each other at a right angle through a common earth electrode 18 arranged in the position opposed to the driving electrode 19 and the detecting electrode 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to ultrasonic vibration of a piezoelectric vibrator in a gyroscope used for posture control of a moving body such as a ship or an automobile and equipment mounted on the moving body itself and a navigation system of an automobile. The present invention relates to a piezoelectric vibrating gyro, and particularly to a piezoelectric vibrating gyro that uses an energy trapping thickness shear vibration mode as a vibration mode of a piezoelectric vibrator and has a simple structure and is easily supported.

[0002]

2. Description of the Related Art A piezoelectric vibrating gyro is a gyroscope that utilizes a mechanical phenomenon in which a Coriolis force is generated in a direction perpendicular to the vibrating direction when a rotating angular velocity is applied to a vibrating object. Generally, in a complex vibration system configured to be able to excite vibrations in two different directions that are orthogonal to each other, when the oscillator is rotated with one vibration being excited, the action of the Coriolis force described above causes a direction perpendicular to this vibration. Force acts on the other, and the other vibration is excited. Since the magnitude of this vibration is proportional to the magnitude of the vibration on the input side and the rotation angular velocity, the magnitude of the rotation angular velocity can be obtained from the magnitude of the output voltage when the input voltage is constant.

FIG. 5 is a perspective view showing the structure of a conventional piezoelectric vibrating gyroscope. A metal triangular prism 510 having an equilateral triangular cross-section has electrodes formed on the two surfaces at approximately the center of the three surfaces, and the thickness Piezoelectric ceramic thin plates 511, 512, 513 polarized in the direction are joined. The metal triangular prism 510 can flexurally vibrate at substantially the same resonance frequency in the direction connecting the respective sides and the facing apexes, and as shown in FIG. 6, one piezoelectric ceramic thin plate 5 is used.
When a voltage having a frequency substantially equal to this resonance frequency is applied to 11, the surface to which the piezoelectric ceramic thin plate 511 is bonded is flexed and vibrated in a direction in which it becomes uneven. In addition, as shown in FIG. 7, two adjacent piezoelectric ceramic thin plates 511 and 512 are provided.
When a voltage having a frequency substantially equal to the resonance frequency of the metal triangular prism 510 having the same amplitude and the same phase is applied to the metal triangular prism 5
No. 10 is bending vibration in a direction in which the surface to which the piezoelectric ceramic thin plate 511 is bonded becomes uneven, and the piezoelectric ceramic thin plate 512.
The bending vibration in the direction in which the surface joined to is uneven is combined, and the bending vibration in the direction in which the surface joined to the remaining piezoelectric ceramic thin plate 513 becomes uneven. On the other hand, as shown in FIG. 8, two piezoelectric ceramic thin plates 511 and 512 adjacent to each other.
When a voltage having a frequency substantially equal to the resonance frequency of the metal triangular prism 510 having the same amplitude and opposite phase is applied to the metal triangular prism 51,
0 indicates bending vibration in a direction in which the surface to which the piezoelectric ceramic thin plate 511 is bonded becomes uneven, and the piezoelectric ceramic thin plate 512.
The bending vibration in the direction in which the surface joined to is uneven is combined, and bending vibration is performed in the direction parallel to the surface joined to the remaining piezoelectric ceramic thin plate 513.

In the state shown in FIG. 7, when the metal triangular prism 510 is rotated about the center in the lengthwise direction, a Coriolis force acts to bond a piezoelectric ceramic thin plate 513 to the metal triangular prism 510 as shown in FIG. Flexural vibration occurs in a direction perpendicular to the direction in which the surface becomes uneven. As shown in FIG. 8, since the bending vibration of the metal triangular prism 510 in the direction parallel to the piezoelectric ceramic thin plate 513 is obtained by applying voltages of the same amplitude and opposite phase to the piezoelectric ceramic thin plates 511 and 512, the opposite Due to the effect, when the metal triangular prism 510 is flexurally vibrated in a direction parallel to the piezoelectric ceramic thin plate 513, voltages of the same amplitude and opposite phase are generated in the piezoelectric ceramic thin plates 511 and 512, and the piezoelectric ceramic thin plate 511 is driven for driving. One of the voltages applied to 512 and 512 decreases by that amount, and the other voltage increases by that amount. Therefore, the voltage difference between the terminal voltages of the piezoelectric ceramic thin plates 511 and 512 is proportional to the angular velocity of rotation of the metal triangular prism 510.

[0005]

In the conventional piezoelectric vibrating gyro shown in FIGS. 5 to 9, since the bending vibration mode of the vibrator is used, the vibration is supported and fixed at the position of the vibration node. Must be done in. However, theoretically, a vibration node is a point or line that has no width or area, so when supported by a line of finite dimensions, it is unavoidable that it will be affected by the support, and the gyro characteristics will deteriorate. Was occurring. Further, if the diameter of the support wire is reduced in order to reduce the influence of the support, there is a drawback that the durability against external vibration or impact deteriorates.

The object of the present invention is to eliminate the drawbacks of the conventional piezoelectric vibrating gyroscope, have a simple structure, have little influence on the gyro characteristics due to supporting and fixing, and can firmly support the vibrating gyroscope. It is to provide a piezoelectric vibrating gyro with excellent impact characteristics.

[0007]

According to the present invention, electrodes are formed on one of the main surfaces facing each other, and
Two piezoelectric plates polarized in a direction parallel to the main surface are provided, and the two piezoelectric plates are arranged such that the directions of the polarization are orthogonal to each other via an electrode arranged at a position facing the electrode. A piezoelectric vibrating gyro is obtained in which the other of the main surfaces is joined to each other.

That is, according to the present invention, two energy trap oscillators in the thickness shear mode, which are formed by forming partial electrodes facing each other substantially at the center of a piezoelectric plate whose polarization direction is parallel to the plate surface, are used. A piezoelectric vibrating gyro, which is characterized in that the elements are joined so as to be orthogonal to each other, is obtained.

[0009]

By the way, the intermediate frequency filter of the FM radio or television uses an energy trapping vibration mode different from the bending vibration mode described above. The energy trapping vibration mode is a vibration mode in which the energy of vibration is concentrated near the drive electrodes, and there are many vibrations such as longitudinal vibration and shear vibration in the thickness direction of the piezoelectric plate and longitudinal vibration and shear vibration in the width direction of the piezoelectric rectangular plate. It is subdivided into vibration modes.

FIG. 10 is a plan view (a) and a sectional view (b) showing the structure of an energy trap type vibrator included in a 10.7 MHz ceramic filter for FM radio. Figure 1
In 0 (a) and (b), this vibrator is 6mm ×
Driving electrodes 11, 11 'and 12 are formed in a region having a diameter of about 1.5 mm at a substantially central portion of a piezoelectric plate 10 having a thickness of 6 mm and a thickness of 0.2 mm.

A 10.7 MHz ceramic filter for FM radio is formed by coating the vibrator with a resin or the like. Here, as described above, in the energy trapping vibration, the vibration energy is concentrated in the vicinity of the drive electrodes, and therefore, for example, as shown in FIG.
If a cavity portion is formed on both sides of a region having a diameter of 3 mm centering on 2, the oscillator characteristics are hardly affected even if the other portions are fixed by the resin 13. That is, it is possible to obtain a filter in which lead terminals are free to be formed and which is not affected by the support.

The piezoelectric vibration gyro according to the present invention utilizes such an energy trapping vibration mode.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A piezoelectric vibrating gyroscope according to an embodiment of the present invention will be described below with reference to the drawings.

First, the operation of the vibrator (piezoelectric plate) used in the present piezoelectric vibrating gyro will be described. FIG. 3 is a plan view (a) and a sectional view (b) showing the structure of the energy trap type thickness shear oscillator. In FIGS. 3 (a) and 3 (b), the polarization direction is in the central portion of the piezoelectric plate 10 ′ whose polarization direction is parallel to the plane,
Opposing partial electrodes 14 and 14 'are formed. If the dimensions of the partial electrodes 14 and 14 'are appropriately designed in accordance with the characteristics of the piezoelectric material used, an energy trap type thickness shear oscillator can be constructed. The thickness-shear vibration is vibration in which the displacement direction is parallel to the plate surface and the wave traveling direction is the thickness direction.For example, the displacement distribution in the thickness direction when resonating at half wavelength is As shown in 4. Particularly, in the case of the vibrator shown in FIG. 4, the displacement direction is the x direction, which coincides with the polarization direction.

FIG. 1 is a perspective view showing a piezoelectric vibrating gyro according to this embodiment. In FIG. 1, the present piezoelectric vibrating gyro includes piezoelectric plates 15 and 16. A drive electrode 19 and a detection electrode 20 are formed on one of the plate surfaces of the piezoelectric plates 15 and 16, respectively. In addition, the piezoelectric plates 15 and 16 are in a direction parallel to the plate surface (direction indicated by an arrow in the figure).
Is polarized to. The piezoelectric plates 15 and 16 are the drive electrodes 1
The other plate surfaces are joined to each other via a common ground electrode 18 arranged at a position facing the sensor 9 and the detection electrode 20 so that the polarization directions thereof are orthogonal to each other.

Next, the operation of this gyro will be described. now,
When an AC voltage having a frequency substantially equal to the resonance frequency in the one-wavelength resonance of the thickness shear mode corresponding to the thickness t is applied to the drive electrode 19 from an excitation power source (not shown), the thickness shear vibration is excited only near the drive electrode 19. To be done. The direction of displacement at this time coincides with the direction of polarization of the piezoelectric plate 15 being excited as shown in FIG. 2, and is in the x direction. In this state, the piezoelectric plate 16 also vibrates in the same direction, but since the polarization direction is orthogonal to the vibration direction, almost no output voltage is generated at the detection electrode 20 due to this vibration.

Now, when the gyro is rotated about an axis perpendicular to the surface of the piezoelectric plate, a Coriolis force is generated in a direction perpendicular to the vibrating direction, and as shown in FIG. Generates vibration in a right angle direction (y direction). Since this vibration direction is the same as the polarization direction of the piezoelectric plate 16, a voltage proportional to the rotational angular velocity is generated in the detection electrode 20.

The piezoelectric vibrating gyroscope according to the present embodiment vibrates in the energy trapping mode. Therefore, if a cavity is formed in a portion having a diameter approximately twice the area of the drive electrode 19 and the detection electrode 20, the vibration characteristic due to the support is obtained. Has almost no effect. Therefore, there is almost no change in the gyro characteristic due to the support.

[0019]

According to the present invention, an electrode is formed on one of main surfaces facing each other, and two piezoelectric plates polarized in a direction parallel to the main surface are provided. The plate has an electrode arranged at a position facing the electrode,
Since the other of the main surfaces is joined to each other so that the polarization directions are orthogonal to each other, the structure is simple, the gyro characteristics are less affected by supporting and fixing, and it is possible to firmly support. Excellent vibration and shock resistance.

[Brief description of drawings]

FIG. 1 is a perspective view showing a piezoelectric vibrating gyroscope according to an embodiment of the present invention.

FIG. 2 is a displacement distribution diagram of the piezoelectric vibration gyro shown in FIG.

FIG. 3 is a diagram showing a structural example of a thickness-shear mode energy trap type vibrator used in the piezoelectric vibration gyro shown in FIG.

FIG. 4 is a displacement distribution diagram of the thickness shear mode energy confinement type oscillator shown in FIG.

FIG. 5 is a perspective view showing a conventional piezoelectric vibrating gyro.

FIG. 6 is an explanatory diagram of an operation principle of the piezoelectric vibration gyro shown in FIG.

7 is an explanatory diagram of an operation principle of the conventional piezoelectric vibration gyro shown in FIG.

FIG. 8 is an explanatory diagram of an operation principle of the conventional piezoelectric vibration gyro shown in FIG.

9 is an explanatory diagram of an operation principle of the conventional piezoelectric vibration gyro shown in FIG.

FIG. 10 is a structural diagram of an energy trap oscillator included in a 10.7 MHz ceramic filter for FM radio.

FIG. 11 is a support structure diagram of the energy trap type vibrator shown in FIG.

[Description of Reference Signs] 10 piezoelectric plate 11, 11 ', 12 drive electrode 13 resin 14, 14' partial electrode 15, 16 piezoelectric plate 18 common ground electrode 19 drive electrode 20 detection electrode 510 metal triangular prism 511, 512, 513 piezoelectric ceramic thin plate

Claims (1)

[Claims] 1. An electrode is formed on one of main surfaces facing each other, and two piezoelectric plates polarized in a direction parallel to the main surface are provided. A piezoelectric vibrating gyro, wherein the other of the main surfaces is joined to each other so that the directions of the polarizations are orthogonal to each other via electrodes arranged at opposing positions.