JP3521315B2 - Piezoelectric vibration gyro - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic vibration of a piezoelectric vibrator in a gyroscope used for a camera navigation system or a camera-integrated VTR. The present invention relates to a piezoelectric vibrating gyroscope using the same. 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 direction of the vibration. 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 vibration on the input side and the rotational angular velocity, when the magnitude of the vibration on the input side 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 a regular triangular cross-sectional shape is substantially at the center of the three surfaces,
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 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 with the surface to which the remaining piezoelectric ceramic thin plate 113 is bonded. Bending vibration occurs in parallel directions. When the metal triangular prism 110 is rotated around the center in the longitudinal direction in the state of FIG. 9, the surface of the metal triangular prism 110 to which the piezoelectric ceramic thin plate 113 is joined is formed on the metal triangular prism 110 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 of 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. In the conventional piezoelectric vibrating gyroscope shown in FIGS. 7 to 11, since the bending vibration mode of the columnar sound side is used, the vibrator is supported and fixed by vibration. Must be done at the position of the clause. However, the nodes of vibration are theoretically points or lines that have no width or area, so if they are supported by a line with finite dimensions, etc., it is inevitable that they will be 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 vibrator. 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 driving electrode, for example, as shown in FIG. 12, a piezoelectric plate 10 having a size of 6 mm × 6 mm and a thickness of 0.2 mm is used. 1.5mm diameter at the center
Where drive electrodes 11, 11 'and 12 are formed in the region of
In a 10.7MHz ceramic filter for radio,
As shown in FIG. 14, the drive 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 and supporting and fixing of input / output lead terminals, can be firmly supported, and has vibration and vibration resistance. An object of the present invention is to provide a piezoelectric vibrating gyroscope having excellent impact characteristics. According to the present invention, a piezoelectric plate having a polarization axis in a thickness direction is located at a central portion on two parallel planes of the piezoelectric plate and is separated by a predetermined distance. Forming a first pair of partial electrodes facing each other, and arranging one of the first pair of partial electrodes on one of the same plane and the opposite plane to form a first parallel electric field excitation type thickness shear mode. Forming a second pair of partial electrodes facing each other at a predetermined interval in a direction orthogonal to a facing line formed by the first pair of partial electrodes, A piezoelectric vibration gyro is characterized in that one of the pair of partial electrodes is arranged on one of the same plane and on the opposite plane to constitute a second parallel electric field excitation type thickness-shear mode energy trapping vibrator. can get. Next, embodiments 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 and 15 ′, the interaction between the partial electrodes 15 and 15 ′ is caused by the interaction with the polarization in the orthogonal thickness direction. 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 both the displacement and the propagation direction of the wave are 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 is a perspective view showing the structure of an embodiment of the piezoelectric vibrating gyroscope according to the present invention. As shown in FIG. 4, a first pair of partial electrodes 15, 15 '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 16 and 1 are provided on one surface of the piezoelectric plate 14 at a substantially central portion thereof.
6 'are formed so as to face each other at a predetermined interval in a direction perpendicular to a line connecting the first pair of partial electrodes 15, 15. In FIG. 4, the displacement direction, that is, the vibration direction is changed by the partial electrodes 15 and 15 '.
The first thickness-shear mode energy trapping oscillator in the opposing direction of 5 ′ can be formed, and at the same time, the partial electrode 1
6 and 16 ', the vibration direction is similarly changed to the partial electrode 16,
A composite vibrator 17 having a second thickness-shear mode energy trapping vibrator in the direction opposite to 16 'can be obtained. 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 confinement 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 the 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. A right-angled vibration in the y-direction occurs. Since the vibration direction is the same as the vibration direction of the partial electrodes 16, 16 ', a voltage proportional to the rotational angular velocity is generated between the partial electrodes 16, 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 approximately twice as large. If the composite vibrator 17 is fixed with a resin having a cavity formed in a diameter portion, there is almost no influence of the vibration characteristics by the support. Therefore, there is almost no change in the gyro characteristics due to the support. FIG. 6 is a perspective view showing another embodiment of the present invention. In FIG. 6, the piezoelectric plate 14 whose polarization direction is the thickness direction is shown.
A first pair of partial electrodes 1
8, 18 'are formed so as to face each other at a predetermined interval. A second pair of partial electrodes 19, 19 ′ are provided on the other surface at the substantially central portion of the piezoelectric plate 14 at a predetermined interval in a direction orthogonal to a line connecting the first pair of partial electrodes 18, 18. Are formed so as to face each other. The composite vibrator 1 is composed of the piezoelectric plate 14, the first pair of partial electrodes 18, 18 'and the second pair of partial electrodes 19, 19'.
7 'is constituted. In the embodiment shown in FIG. 6, similarly to the embodiment 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 the composite vibrator 17 'is rotated around an axis perpendicular to the surface of the piezoelectric plate 14, Coriolis force is generated in a direction perpendicular to the vibration direction, 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 partial electrodes 19 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. 4, a first pair of partial electrodes and a second pair of partial electrodes are formed on the same surface of the piezoelectric plate 14, and in the embodiment shown in FIG. Although the pair of partial electrodes and the second pair of partial electrodes are formed on different surfaces of the piezoelectric plate 14, the present invention is not limited to this. One of the first pair of partial electrodes and the second pair of It may be formed on a different surface of the plate 14. The piezoelectric vibrating gyroscope of the present invention has a simple structure, has almost no influence on the gyro characteristics due to support and fixation, can be firmly supported, and is resistant to vibration and shock. Excellent characteristics.

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 vibrator 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 oscillator used in the present invention. FIG. 4 is a perspective view showing an embodiment of a piezoelectric vibrating gyroscope according to the present invention. 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 another embodiment of the 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 operation 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 operating 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 an energy-trapped oscillator. [Description of Signs] 14 Piezoelectric plates 15, 16, 18, 19, 15 ', 16', 18 ', 1
9 'partial electrode 17, 17' composite oscillator

Claims (1)

(57) [Claim 1] A piezoelectric plate having a polarization axis in a thickness direction, which is located at a central portion on two parallel planes of the piezoelectric plate and faces at a predetermined interval. Forming a pair of partial electrodes,
One of the first pair of partial electrodes is arranged on one of the same plane and on the opposite plane to form a first parallel electric field excitation type thickness-shear mode energy trapping oscillator, and Forming a second pair of partial electrodes facing each other at a predetermined interval in a direction orthogonal to the opposing line formed by the pair of partial electrodes, and placing one of the second pair of partial electrodes on the same plane and on the opposite plane. A piezoelectric vibratory gyroscope comprising a second parallel electric field excitation type thickness-shear mode energy trapping vibrator arranged on one of the above.