JP3172924B2 - Piezoelectric vibration gyro - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the ultrasonic vibration of a piezoelectric vibrator in a gyroscope used for attitude control of a moving body itself such as a ship or a car and a device mounted thereon and a navigation system of a car. The present invention relates to a piezoelectric vibrating gyroscope, and more particularly to a piezoelectric vibrating gyroscope with a simple structure and easy support using an energy trapping thickness shear vibration mode as a vibration mode of a piezoelectric vibrator.

[0002]

2. Description of the Related Art A piezoelectric vibrating gyroscope is a gyroscope utilizing a mechanical phenomenon that when a rotating angular velocity is given to a vibrating object, a Coriolis force is generated in a direction perpendicular to the direction of the vibration. Generally, in a composite vibration system configured to be able to excite vibrations in two different directions orthogonal to each other, when the vibrator is rotated while one of the vibrations is excited, the direction perpendicular to this vibration is obtained by the action of the aforementioned Coriolis force. And the other vibration is excited. Since the magnitude of the vibration is proportional to the magnitude of the vibration on the input side and the rotational angular velocity, the magnitude of the rotational angular velocity can be obtained from the magnitude of the output voltage when the input voltage is kept constant.

FIG. 5 is a perspective view showing the structure of a conventional piezoelectric vibrating gyroscope. The metal triangular prism 510 having an equilateral triangular cross-section has electrodes formed on both sides substantially at the center of three sides thereof. The piezoelectric ceramic thin plates 511, 512, and 513 polarized in the directions are joined. The metal triangular prism 510 can bend and vibrate at substantially the same resonance frequency in the direction connecting each side and the apex facing the same, and as shown in FIG.
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 joined vibrates in a direction in which the surface becomes uneven. 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
Reference numeral 10 denotes 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.
Is combined with bending vibration in a direction in which the surface joined with the piezoelectric ceramic thin plate 513 becomes uneven. On the other hand, as shown in FIG. 8, two adjacent piezoelectric ceramic thin plates 511, 512
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
0 is bending vibration in the direction in which the surface to which the piezoelectric ceramic thin plate 511 is joined becomes uneven, and the piezoelectric ceramic thin plate 512
Is combined with the bending vibration in the direction in which the surface where is bonded becomes uneven, and bending vibration is performed in a direction parallel to the surface where the remaining piezoelectric ceramic thin plates 513 are bonded.

When the metal triangular prism 510 is rotated around the center in the longitudinal direction in the state of FIG. 7, a piezoelectric ceramic thin plate 513 is joined to the metal triangular prism 510 by the action of Coriolis force as shown in FIG. Bending vibration occurs in a direction perpendicular to the direction in which the surface becomes uneven. As shown in FIG. 8, 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 phases to the piezoelectric ceramic thin plates 511 and 512. When the metal triangular prism 510 is bent and vibrated in a direction parallel to the piezoelectric ceramic thin plate 513 due to the effect, voltages of the same amplitude and opposite phases are generated in the piezoelectric ceramic thin plates 511 and 512, and the piezoelectric ceramic thin plate 511 is driven. , 512 decreases correspondingly, and the other increases correspondingly. Therefore, the voltage of the difference between the terminal voltages of the piezoelectric ceramic thin plates 511 and 512 is a voltage proportional to the rotational angular velocity of the metal triangular prism 510.

[0005]

In the conventional piezoelectric vibrating gyroscope shown in FIGS. 5 to 9, since the flexural vibration mode of the vibrator is used, the vibrator is supported and fixed at the position of the node of vibration. Must be done in However, the nodes of vibration are theoretically points or lines that do not have a width or area, so if they are supported by a line of finite dimensions, etc., they will be unavoidably affected by the support, and the gyro characteristics will deteriorate. Was occurring. Further, when the diameter of the support wire is reduced to reduce the influence of the support, there is a disadvantage that the durability against external vibrations and impacts is deteriorated.

An object of the present invention is to eliminate the disadvantages of the conventional piezoelectric vibrating gyroscope, to have a simple structure, to have little effect on the gyro characteristics due to support and fixation, to be able to support firmly, An object of the present invention is to provide a piezoelectric vibrating gyroscope having excellent impact characteristics.

[0007]

According to the present invention, electrodes are formed on one of the main surfaces facing each other, and
It has two piezoelectric plates polarized in a direction parallel to the main surface, and the two piezoelectric plates are arranged so that the directions of the polarization are orthogonal to each other via an electrode arranged at a position facing the electrode. The piezoelectric vibrating gyroscope is characterized in that the other of the main surfaces is joined to each other.

In other words, according to the present invention, two thickness-shear mode energy trapping vibrators each formed by forming a partial electrode facing a substantially central portion of a piezoelectric plate whose polarization direction is parallel to the plate surface are connected to the polarization direction. Are formed so as to be orthogonal to each other, thereby obtaining a piezoelectric vibrating gyroscope.

[0009]

By the way, the intermediate frequency filter of the FM radio or the television uses an energy trapping vibration mode different from the bending vibration mode described above. The energy confinement vibration mode is a vibration mode in which the energy of vibration is concentrated near the drive electrode, and includes longitudinal vibration and sliding vibration in the thickness direction of the piezoelectric plate, longitudinal vibration and sliding vibration in the width direction of the piezoelectric rectangular plate, and the like. Vibration mode.

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. FIG.
0 (a) and (b), this vibrator is 6 mm ×
Drive electrodes 11, 11 'and 12 are formed in a region of about 1.5 mm in diameter 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 a vibrator with a resin or the like. Here, as described above, in the energy trapping vibration, since the energy of the vibration is concentrated near the driving electrode, for example, as shown in FIG.
If hollow portions are formed on both sides of a region having a diameter of 3 mm centered on 2, even if other portions are fixed with resin 13, the characteristics of the vibrator are hardly affected. That is, a filter in which the formation of the lead terminals is free and which is not affected by the support can be obtained.

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

[0013]

DETAILED 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 gyroscope will be described. FIG. 3 is a plan view (a) and a cross-sectional view (b) showing the structure of the energy trap type thickness shear resonator. In FIGS. 3A and 3B, the polarization direction is at the center of the piezoelectric plate 10 'parallel to the plane.
Opposing partial electrodes 14, 14 'are formed. If the dimensions of the partial electrodes 14 and 14 'are appropriately designed according to the characteristics of the piezoelectric material used, an energy trap type thickness-shear vibrator can be formed. The thickness shear vibration is a vibration in which the direction of displacement is parallel to the plate surface and the traveling direction of the wave is the thickness direction.For example, the displacement distribution in the thickness direction when resonating at a half wavelength is shown in FIG. As shown in FIG. In particular, in the case of the vibrator shown in FIG. 4, the displacement direction coincides with the direction of polarization and becomes the x direction.

FIG. 1 is a perspective view showing a piezoelectric vibrating gyroscope according to this embodiment. In FIG. 1, the present piezoelectric vibrating gyroscope has 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. Further, the piezoelectric plates 15 and 16 are in a direction parallel to the plate surface (the direction indicated by the arrow in the figure).
Is polarized. The piezoelectric plates 15 and 16 are
The other of the plate surfaces is joined to each other via a common ground electrode 18 arranged at a position facing the detection electrode 9 and the detection electrode 20 so that the directions of the respective polarizations are orthogonal to each other.

Next, the operation of the gyro will be described. now,
When an AC voltage having a frequency substantially equal to the resonance frequency in the one-wavelength resonance in the thickness-shear mode corresponding to the thickness t is applied to the drive electrode 19 from an excitation power supply (not shown), the thickness-shear vibration is excited only in the vicinity of the drive electrode 19. Is 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. In this state, the piezoelectric plate 16 also oscillates in the same direction, but since the polarization direction is orthogonal to the oscillating direction, almost no output voltage is generated at the detection electrode 20 due to this oscillation.

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

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

[0019]

According to the present invention, there are provided two piezoelectric plates each having an electrode formed on one of the main surfaces facing each other and polarized in a direction parallel to the main surface. The plate is provided with an electrode disposed at a position facing the electrode,
The other of the main surfaces is joined to each other so that the directions of the polarization are orthogonal to each other, so that the structure is simple, the influence on the gyro characteristics due to the support and the fixation is small, and the support can be firmly performed. Excellent vibration and shock resistance.

[Brief description of the 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 in the piezoelectric vibrating gyroscope 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 vibrating gyroscope shown in FIG.

4 is a displacement distribution diagram of the thickness-shear mode energy trap type vibrator shown in FIG.

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

FIG. 6 is an explanatory diagram of the operation principle of the piezoelectric vibrating gyroscope shown in FIG.

7 is an explanatory diagram of the operation principle of the conventional piezoelectric vibrating gyroscope shown in FIG.

FIG. 8 is an explanatory view of the operation principle of the conventional piezoelectric vibrating gyroscope shown in FIG.

FIG. 9 is an explanatory view of the operation principle of the conventional piezoelectric vibrating gyroscope shown in FIG.

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

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

[Explanation of symbols]

 Reference Signs List 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)

(57) [Claims] An electrode is 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. The two piezoelectric plates are A piezoelectric vibrating gyroscope, wherein the other of the main surfaces is joined to each other via electrodes arranged at opposing positions so that the directions of the polarization are orthogonal to each other.