JP3240416B2 - 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 piezoelectric vibratory gyroscope using ultrasonic vibration of a piezoelectric vibrator among gyroscopes used for a camera shake correction of an automobile navigation system and a camera-integrated VTR.

[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 applied to a vibrating object, a Coriolis force is generated in a direction perpendicular to the vibration direction. In general, in a composite vibration system configured to be able to excite vibrations in two different directions that are orthogonal to each other, when one of the vibrations is excited and the vibrator is rotated, the aforementioned Coriolis force acts in a direction perpendicular to this vibration. The force works and the other vibration is excited. Since the magnitude of this vibration is proportional to the magnitude of the input-side vibration and the rotational angular velocity, when the magnitude of the input-side vibration is constant, the magnitude of the rotational angular velocity can be obtained from the magnitude of the output voltage. .

FIG. 7 is a perspective view showing the structure of a conventional piezoelectric vibrating gyroscope. As shown in FIG. 7, the metal triangular prism 110 having an equilateral triangular cross-sectional shape is provided at substantially the center of three surfaces thereof.
Electrodes are formed on both sides, and piezoelectric ceramic thin plates 111, 112, 113 polarized in the thickness direction are joined. The metal triangular prism 110 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. 8, a single piezoelectric ceramic thin plate 111 has almost the same resonance frequency. When a voltage having a frequency is applied, the surface to which the piezoelectric ceramic thin plate 111 is bonded vibrates in a bending direction in a direction in which the surface becomes uneven.

Further, as shown in FIG. 9, when a voltage having a frequency substantially equal to the resonance frequency of a metal triangular prism 110 having the same amplitude and the same phase is applied to two adjacent piezoelectric ceramic thin plates 111 and 112, the metal triangular prism 110 becomes The bending vibration in the direction in which the surface to which the piezoelectric ceramic thin plate 111 is bonded becomes uneven and the bending vibration in the direction in which the surface to which the piezoelectric ceramic thin plate 112 is bonded becomes uneven are combined, and the surface to which the remaining piezoelectric ceramic thin plate 113 is bonded is formed. It bends and vibrates in the direction of unevenness.

On the other hand, as shown in FIG. 10, when a voltage having a frequency substantially equal to the resonance frequency of a metal triangular prism 110 having the same amplitude and opposite phase is applied to two adjacent piezoelectric ceramic thin plates 111 and 112, the metal triangular prism 110 The bending vibration in the direction in which the surface to which the piezoelectric ceramic thin plate 111 is bonded becomes uneven and the bending vibration in the direction in which the surface to which the piezoelectric ceramic thin plate 112 is bonded becomes uneven are combined with the surface to which the remaining piezoelectric ceramic thin plate 113 is bonded. Bending vibration in parallel direction.

When the metal triangular prism 110 is rotated about the center in the longitudinal direction as the axis in the state of FIG. 9, the surface of the metal triangular prism 110 to which the piezoelectric ceramic thin plate 113 is bonded is formed by the action of Coriolis force as shown in FIG. Bending vibration occurs in a direction perpendicular to the direction of the unevenness. As shown in FIG. 10, the bending vibration of the metal triangular prism 110 in the direction parallel to the piezoelectric ceramic thin plate 113 is obtained by applying voltages of the same amplitude and opposite phases to the piezoelectric ceramic thin plates 111 and 112, so that the opposite effects are obtained. When the metal triangular prism 110 is bent and vibrated in a direction parallel to the piezoelectric ceramic thin plate 113, a voltage having the same amplitude and opposite phase is generated in the piezoelectric ceramic thin plates 111 and 112, and the piezoelectric ceramic thin plates 111 and 112 are driven for driving. One of the applied voltages decreases correspondingly, and the other increases accordingly. Therefore, the voltage of the difference between the terminal voltages of the piezoelectric ceramic thin plates 111 and 112 is a voltage proportional to the rotational angular velocity of the metal triangular prism 110.

[0007]

In the conventional piezoelectric vibrating gyroscope shown in FIGS. 7 to 11, the bending / vibration mode of the columnar sound side is used. Must be done in position. 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, if the diameter of the support wire is reduced to reduce the influence of the support, there is a problem that the durability against external vibrations and impacts is deteriorated.

FIG. 12 is a plan view showing the structure of a conventional type energy trapping oscillator. FIG. 13 is a cross-sectional view showing the structure of a conventional type energy trapping vibrator. Energy trapped vibration is a vibration mode in which the energy of the vibration is concentrated near the drive electrode, and many vibrations such as longitudinal vibration and sliding vibration in the thickness direction of the piezoelectric plate and longitudinal vibration and sliding vibration in the width direction of the piezoelectric rectangular plate There is a vibration mode, which is widely used for intermediate frequency filters of FM radios and televisions. As described above, since the energy of the energy confinement vibration is concentrated near the drive electrode, for example, as shown in FIG. 12, a 6 mm × 6 mm piezoelectric plate 10 having a thickness of 0.2 mm is used. The diameter of the center is 1.5mm
Where drive electrodes 11, 11 'and 12 are formed in the region
In a 10.7MHz ceramic filter for radio,
As shown in FIG. 14, the driving electrodes 11, 11 'and 1
If hollow portions are formed on both sides of a region having a diameter of 3 mm around the center 2, even if other portions are fixed with the resin 13, the characteristics of the vibrator are hardly affected. That is, a piezoelectric vibrator in which the formation of the lead terminals is free and which is not affected by the support can be obtained.
However, this piezoelectric vibrator has a problem that it is difficult to configure a piezoelectric vibrating gyroscope.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a structure which is simple in structure, has little influence on gyro characteristics due to taking out, supporting and fixing of input / output lead terminals, can be firmly supported, and is vibration and vibration resistant. An object of the present invention is to provide a piezoelectric vibrating gyroscope having excellent impact characteristics.

[0010]

According to the present invention, a first pair of partial electrodes opposed to a piezoelectric plate having a polarization axis in a thickness direction at a predetermined interval are formed, and the first pair of partial electrodes are formed . Partial electricity
One of the poles on the same plane or on the opposite plane
To form a first parallel electric field excitation type thickness-shear mode energy confinement vibrator, and oppose each other at a predetermined interval in a direction orthogonal to an opposing line formed by the first pair of partial electrodes. Forming a second pair of partial electrodes ,
One of the second pair of partial electrodes is coplanar and
A second parallel electric field excitation type thickness-shear mode energy confinement oscillator by arranging it on one of the surfaces ,
A small number of the first and second partial electrodes;
At least one of the piezoelectric vibrating gyroscopes is characterized in that one of them is arranged on a different plane .

[0011]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

First, a parallel electric field excitation type thickness-shear mode energy trapping oscillator used in the present invention is shown in FIG.
This will be described with reference to FIG. As shown in FIGS. 1 and 2, a pair of partial electrodes 15 and 15 ′ are formed so as to face each other on the same plane at the center of the piezoelectric plate 14 whose polarization direction is the thickness direction. Since an electric field in a direction substantially parallel to the surface of the piezoelectric plate 14 is applied to the portion sandwiched between the partial electrodes 15, 15 ', the partial electrodes 15, 15' By appropriately designing according to the dimensions of 'and the characteristics of the piezoelectric material to be used, a parallel electric field excitation type thickness-shear energy-trapping oscillator can be formed in this portion. The thickness shear vibration is a vibration in which the displacement and the wave propagation direction are both parallel to the plate surface, and the displacement distribution in the thickness direction when resonating at a half wavelength is as shown in FIG.

FIG. 4 shows two pairs of electrodes according to the principle described above .
It is a perspective view which shows the structural example of the combined piezoelectric vibrating gyroscope. As shown in FIG. 4, a first pair of partial electrodes 1 is provided on one surface of a substantially central portion of the piezoelectric plate 14 whose polarization direction is the thickness direction.
5, 15 'are formed so as to face each other at a predetermined interval. On one surface of the substantially central portion of the piezoelectric plate 14, a second pair of partial electrodes 16 and 16 'are spaced apart from each other by a predetermined distance in a direction perpendicular to a line connecting the first pair of partial electrodes 15 and 15. And are formed so as to face each other. In FIG. 4, the first thickness shear mode energy trapping vibrator in which the displacement direction, that is, the vibration direction is the direction opposite to the partial electrodes 15, 15 'can be constituted by the partial electrodes 15, 15', and at the same time, the partial electrodes 16, 15 'are formed. Similarly, a composite vibrator 17 having a second thickness-shear mode energy confinement vibrator whose vibration direction is opposite to that of the partial electrodes 16 and 16 'can be obtained by 16'. Since the resonance frequency of the thickness-shear mode is substantially determined by the thickness when the material is the same, the resonance frequencies of the first and second thickness-shear mode energy trapping vibrators are respectively equal.

In FIG. 4, one of the partial electrodes 15, 1
When an AC voltage having a frequency substantially equal to the resonance frequency of the thickness-shear mode is applied during 5 ′, thickness-shear vibration is excited only in the vicinity of the electrode. The direction of the displacement at that time coincides with the direction in which the exciting partial electrodes 15 and 15 'face each other as shown in FIG. In this state, almost no output voltage is generated between the partial electrodes 16 and 16 '. Now, when this composite vibrator 17 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. Vibration in the right y-direction occurs. Since the vibration direction is the same as the vibration direction of the partial electrodes 16 and 16 ', a voltage proportional to the rotational angular velocity is generated between the partial electrodes 16 and 16'.

Since the composite vibrator 17 shown in FIG. 4 vibrates in the energy confinement mode, as described with reference to FIG. 11, the area of the partial electrodes 15, 15 ', 16, 16' is about twice as large. If the composite vibrator 17 is fixed with a resin in which a cavity is formed in a diameter portion, there is almost no influence of vibration characteristics due to the support. Therefore, there is almost no change in the gyro characteristics due to the support.

[0016] Here, with reference to FIG. 6, the piezoelectric vibration of the present invention
It describes an embodiment of a dynamic gyro. In FIG. 6, a first pair of partial electrodes 18 and 18 'are formed on one surface of a substantially central portion of the piezoelectric plate 14 whose polarization direction is the thickness direction so as to oppose at a predetermined interval. A second pair of partial electrodes 19 and 19 ′ are provided on the other surface substantially at the center of the piezoelectric plate 14.
They are formed so as to face each other at a predetermined interval in a direction orthogonal to the line connecting 8, 18. The piezoelectric vibrator 14, the first pair of partial electrodes 18, 18 'and the second pair of partial electrodes 19, 19' form a composite vibrator 17 '.

In the embodiment shown in FIG. 6, as in the configuration example shown in FIG.
When an AC voltage having a frequency substantially equal to the resonance frequency of the thickness-shear mode is applied, thickness-shear vibration is excited only in the vicinity of the electrode. The direction of displacement at that time coincides with the direction in which the partial electrodes 18 and 18 'face each other as in the case of FIG.
It becomes the x direction. In this state, almost no output voltage is generated between the partial electrodes 19 and 19 '. Now, when this composite vibrator 17 'is rotated around an axis perpendicular to the surface of the piezoelectric plate 14, a Coriolis force is generated in a direction perpendicular to the direction of vibration, and as in the case of FIG. Vibration occurs in the y-direction perpendicular to the direction of vibration. This vibration direction is the partial electrode 1
Since the vibration direction is the same as that of the vibrations 9 and 19 ', a voltage proportional to the rotational angular velocity is generated between the partial electrodes 19 and 19'.

In the embodiment shown in FIG . 6, the first pair of partial electrodes and the second pair of partial electrodes are formed on different surfaces of the piezoelectric plate 14. However, the present invention is not limited to this. One of the electrode and the second pair of partial electrodes may be formed on different surfaces of the piezoelectric plate 14.

[0019]

The piezoelectric vibrating gyroscope of the present invention has a simple structure, has almost no effect on the gyroscope characteristics due to support and fixation, can be firmly supported, and has excellent vibration and shock resistance characteristics. ing.

[Brief description of the drawings]

FIG. 1 is a plan view showing a parallel electric field excitation type thickness-shear mode energy trapping oscillator used in the present invention.

FIG. 2 is a cross-sectional view showing a parallel electric field excitation type thickness-shear mode energy trapping oscillator used in the present invention.

FIG. 3 is an explanatory diagram for explaining a displacement distribution in a parallel electric field excitation type thickness-shear mode energy trapping vibrator used in the present invention.

FIG. 4 shows the energy trapping oscillator of FIGS. 1 to 3
FIG. 2 is a perspective view showing an example of a configuration of a piezoelectric vibrating gyroscope using a gyroscope.

FIG. 5 is an explanatory diagram for explaining a displacement distribution in the piezoelectric vibrating gyroscope according to the present invention.

FIG. 6 is a perspective view showing an embodiment of a piezoelectric vibrating gyroscope according to the present invention.

FIG. 7 is an explanatory diagram for explaining the structure and operating principle of a conventional piezoelectric vibrating gyroscope.

FIG. 8 is an explanatory diagram for explaining the structure and operating principle of a conventional piezoelectric vibrating gyroscope.

FIG. 9 is an explanatory diagram for explaining the structure and operation principle of a conventional piezoelectric vibrating gyroscope.

FIG. 10 is an explanatory diagram for explaining the structure and operation principle of a conventional piezoelectric vibrating gyroscope.

FIG. 11 is an explanatory diagram for explaining the structure and operation principle of a conventional piezoelectric vibrating gyroscope.

FIG. 12 is a plan view showing a conventional energy trapping vibrator.

FIG. 13 is a cross-sectional view showing a conventional energy trapping vibrator.

FIG. 14 is a cross-sectional view showing a conventional means for supporting a confined vibrator.

[Explanation of symbols]

 14 Piezoelectric plate 15-19, 15'-19 'Partial electrode 17, 17' Composite oscillator

Claims (1)

(57) [Claims] 1. A first pair of partial electrodes facing a piezoelectric plate having a polarization axis in a thickness direction at a predetermined interval ,
One of the first pair of partial electrodes is coplanar and opposite
A first parallel electric field excitation type thickness-shear mode energy confined vibrator arranged on any one of the planes , and an opposing line formed by the first pair of partial electrodes
In the direction orthogonal at a predetermined distance to form a second pair of partial electrodes opposed to the one of said second pair of partial electrodes
A second parallel electric field excitation type thickness-shear mode energy confined oscillator is arranged on one of the same plane and on the opposite plane to form the first and the second each.
At least one of the pair of partial electrodes has a flat surface different from each other.
A piezoelectric vibrating gyro, which is disposed on a surface .