JP3211183B2 - Piezoelectric vibratory gyroscope using energy trapped vibration mode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibratory gyroscope utilizing ultrasonic vibration of a piezoelectric vibrator, and more particularly to a vibratory gyroscope used in a car navigation system or a camera-integrated VTR camera for correcting camera shake. The present invention relates to a piezoelectric vibrating gyroscope that uses an energy-trapping vibration mode as a vibration mode of a vibrator, has a simple structure, is easily supported, and has excellent vibration resistance and shock resistance.

[0002]

2. Description of the Related Art A piezoelectric vibrating gyroscope is a gyroscope utilizing a mechanical phenomenon that when a circuit angular velocity is applied to a vibrating object, a Coriolis force is generated in a direction perpendicular to the vibration direction.

In general, when a vibrator is rotated in a state where one of the vibrations is excited in a composite vibration system configured to be able to excite vibrations in two different directions orthogonal to each other, the above-described vibration and the action of the Coriolis force cause the vibration. A force acts in a perpendicular direction, and the other vibration is excited. Since the magnitude of this vibration is proportional to the amplitude of the vibration on the input side and the rotational angular velocity, when the vibration amplitude on the input side is constant, the magnitude of the applied rotational angular velocity can be obtained from the magnitude of the output voltage. it can.

FIG. 6 is a perspective view showing the structure of a conventional piezoelectric vibrating gyroscope. Referring to FIG. 6, a piezoelectric ceramic thin plate 52 is provided almost at the center of an adjacent surface of a metal prism 51 having a square cross section. 53 are joined. These piezoelectric ceramic thin plates 52 and 53 have electrodes formed on both surfaces, respectively, and are polarized in the thickness direction.

[0005] A metal prism 51 having a square cross section has two bending vibration modes orthogonal to each other, and it is known that, when the characteristics of the material are uniform, the resonance frequencies of the two bending vibration modes are substantially equal. Have been. Therefore, when a voltage having a frequency substantially equal to the resonance frequency of the bending vibration of the metal prism is applied to the piezoelectric ceramics thin plate 52, the surface to which the piezoelectric ceramics 52 are bonded vibrates in a direction in which the surface becomes uneven (y-axis direction). In this state, when the metal prism 51 is rotated around an axis (z-axis) parallel to the length direction, the metal prism 51 is formed in a direction in which the surface to which the piezoelectric ceramic thin plate 53 is joined becomes uneven due to the action of Coriolis force. The bending vibration also occurs in the (x-axis direction), and a voltage is generated in the piezoelectric ceramic thin plate 53 by the piezoelectric effect. The magnitude of this voltage is proportional to the magnitude of the vibration excited by the piezoelectric ceramic thin plate 52 and the magnitude of the applied rotational angular velocity. Accordingly, if the magnitude of the excitation voltage applied to the piezoelectric ceramic thin plate 52 is constant, the voltage generated in the piezoelectric ceramic thin plate 53 is a voltage proportional to the rotational angular velocity of the metal prism 51.

[0006]

In the conventional piezoelectric vibrating gyroscope shown in FIG. 6, since the bending vibration mode of the metal prism is used, the vibrator must be supported and fixed at the position of the vibration node. Must. Further, in the conventional piezoelectric vibrating gyroscope, it is necessary to connect the drive and detection circuits and the electrodes of the vibrator with lead wires, and it has been difficult to suppress variations in characteristics due to variations in connection states. further,
Since a vibrator supported by a holder is mounted on a substrate on which a drive and detection circuit is formed and assembled, it is difficult to form a small and thin piezoelectric vibrating gyroscope.

Accordingly, the technical problem of the present invention is to eliminate the above-mentioned disadvantages of the conventional piezoelectric vibrating gyroscope, to have a simple structure, and to connect input / output terminals without using lead wires. Accordingly, an object of the present invention is to provide a small and thin piezoelectric vibrating gyroscope in which a drive and detection circuit is formed on a substrate having a vibrating gyroscope.

[0008]

According to the present invention, a plurality of driving and detecting electrodes are formed so as to face substantially the center of a piezoelectric plate having a polarization axis component parallel to the main surface. Among the electrodes, an even number of electrodes for detection are formed symmetrically with respect to a straight line parallel to the direction of the polarization axis component parallel to the main surface, a first electrode is formed on one main surface, and the other is formed on the other main surface. of
A portion parallel to the main surface is opposed to the first electrode on the surface.
Second electrode symmetric about a straight line parallel to the direction of the polar axis component
And the third electrode is formed.
-A piezoelectric vibratory gyroscope using the confinement vibration mode was obtained.
It is.

[0009]

According to the present invention, the second and the third
A drive voltage for excitation is applied to each of the electrodes via a resistor, and the second and third electrodes are acted on by the action of Coriolis force generated when the piezoelectric plate is rotated around an axis orthogonal to the main surface. A piezoelectric vibrating gyroscope utilizing the energy confinement vibration mode according to claim 1 characterized in that it is configured to detect a voltage difference generated in the piezoelectric vibrating gyroscope.

Further, according to the present invention, the first electrode is used as a drive electrode, and the second and third electrodes are respectively connected to first and second current detection circuits having a virtual ground function, The plate is configured to detect a difference between output voltages of the first and second current detection circuits caused by the action of Coriolis force generated when the plate is rotated around an axis orthogonal to the main surface. A piezoelectric vibrating gyroscope utilizing the energy confinement vibration mode according to claim 1 is obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing embodiments of the present invention, a vertical electric field excitation type energy trapped thickness shear resonator using a piezoelectric plate will be described below.

FIG. 1 is a plan view showing a basic structure of a vertical electric field excitation type thickness-shear energy trapping vibrator and a cross-sectional view showing only electrode portions. Referring to FIG. 1, an electrode 101 is formed substantially at the center of a piezoelectric plate 10 having a polarization axis component in a direction parallel to the main surface (x-axis direction). The electrodes 102 are formed so as to face each other. When an electric field in the thickness direction is applied by the electrodes 101 and 102, the electrodes 101 and 102 interact with a polarization component in a direction parallel to the main surface orthogonal to the electric field.
A vertical electric field excitation type thickness-shear energy trapped vibrator can be formed in a portion sandwiched between the two. Thickness shear vibration is vibration in which the direction of displacement is parallel to the plate surface and the direction of wave propagation is the thickness direction of the plate. As shown in FIG. 2, when resonance occurs at a half wavelength, a displacement distribution in the thickness direction (z-axis direction) is shown.

Such an energy trapping phenomenon of the piezoelectric vibrator is caused by a local difference in propagation characteristics with respect to the elastic wave of interest, and the energy trapping type vibrator shown in FIG. In this case, the fact that the propagation characteristics of the electrode portions are locally different due to the mass adding effect and the short-circuit effect of the electrodes 101 and 102 is used.

FIG. 3 is a perspective view showing the structure of the piezoelectric vibrator 1 of the energy trap type piezoelectric vibrating gyroscope according to the embodiment of the present invention. In FIG. 3, a first electrode 11 is formed on one surface of a piezoelectric plate 10 having a polarization axis component in a direction parallel to the main surface, and is opposed to the first electrode 11 on the other surface. Second electrode 12 and third electrode 1 symmetrical with respect to a straight line parallel to the direction of the polarization axis component parallel to the main surface
3 are formed.

FIG. 4 is a block diagram including a circuit configuration showing the configuration of an embodiment of the piezoelectric vibrating gyroscope of the present invention constituted by using the piezoelectric vibrator 1 of FIG.

Referring to FIG. 4, in the piezoelectric vibrator, a first electrode 11 is grounded, and an AC power supply 22 is connected to second and third electrodes 12 and 13 via resistors 20 and 21, respectively. Connected, the second and third electrodes 12 and 13
Each is also connected to the input terminal of the differential amplifier circuit 23. The output terminal of the differential amplifier circuit 23 becomes the sensor output of the piezoelectric vibrating gyroscope via the detection circuit 24.

3 and 4, the first electrode 11 is grounded, and the second electrode 12 and the third electrode 13 are connected to an AC power supply 22 via resistors 20 and 21, respectively.

When a drive voltage for excitation having a frequency substantially equal to the resonance frequency of the piezoelectric plate in the thickness-shear mode is applied to the second electrode 12 and the third electrode 13 from the AC power source via the resistors 20 and 21, respectively. , A first electrode 11,
In a region where the second and third electrodes 12 and 13 face each other,
A slip vibration of the energy confinement vibration mode in the direction of the polarization axis component parallel to the main surface is generated. In this state, when the piezoelectric plate 10 is rotated around an axis orthogonal to the main surface, the action of the Coriolis force causes thickness shear vibration perpendicular to the direction of the excited thickness shear vibration.
By the thickness shear vibration generated by this Coriolis force,
Between the first electrode 11 and the second electrode 12, and the first electrode 1
The impedance between the first and third electrodes 13 changes, and as a result, the terminal voltages of the second electrode 12 and the third electrode 13 change. The change in impedance is proportional to the applied angular velocity when the excitation voltage is constant.

Therefore, the difference between the terminal voltages of the second electrode 12 and the third electrode 13 is detected by the differential amplifier circuit 23, and this voltage is synchronously detected at a predetermined timing to thereby apply the applied rotational angular velocity. Can be obtained in proportion to the output voltage.

FIG. 5 is a block diagram including a circuit configuration showing the configuration of another embodiment of the piezoelectric vibrating gyroscope according to the present invention constituted by using the piezoelectric vibrator 1 of FIG.

In FIG. 5, the first electrode 1 of the piezoelectric vibrator is shown.
1 is supplied with a drive voltage via a resistor 34, and a first current detection circuit 35 and a second current detection circuit 36 having a virtual ground function are connected to the second electrode 12 and the third electrode 13, respectively. Have been. Output voltage terminals of the first current detection circuit 35 and the second current detection circuit 36 are connected to input terminals of the differential amplifier circuit 37, respectively. An output terminal of the differential amplifier circuit 37 is connected to the detection circuit 38, and serves as a sensor output of the piezoelectric vibrating gyroscope.

In the following, on the same principle as described with reference to FIG. 4, slip vibration in the energy-trapping vibration mode in the direction of the polarization axis component parallel to the main surface occurs.
When the piezoelectric plate 10 is rotated around an axis perpendicular to the main surface thereof, a thickness shear vibration in a direction perpendicular to the direction of the excited thickness shear vibration is generated by the action of the Coriolis force. The thickness shear vibration generated by the Coriolis force causes a change in the current flowing from the second electrode and the third electrode into the current detection circuits 35 and 36 having a virtual ground function, respectively, and the output voltages of the current detection circuits 35 and 36 are changed. By detecting the difference voltage, the applied rotational angular velocity can be detected.

[0024]

As described above, according to the present invention,
The structure is simple, and the input and output terminals can be connected without using lead wires. A small-sized piezoelectric vibration gyro having excellent impact characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration for explaining a driving principle of a vertical electric field excitation type thickness-shear mode energy trapping vibrator.

FIG. 2 is a diagram showing a displacement distribution of a thickness-shear mode energy confinement vibrator.

FIG. 3 is a perspective view showing a piezoelectric vibrator of the energy confinement type vibrating gyroscope according to the embodiment of the present invention.

FIG. 4 is a block diagram including a circuit configuration showing a configuration of an embodiment of a piezoelectric vibrating gyroscope according to the present invention configured using the piezoelectric vibrator 1 of FIG.

FIG. 5 is a block diagram including a circuit configuration showing a configuration of another embodiment of the piezoelectric vibrating gyroscope of the present invention configured using the piezoelectric vibrator 1 of FIG. 3;

FIG. 6 is a perspective view showing a structural example of a conventional piezoelectric vibrating gyroscope.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric vibrator 10 Piezoelectric plate 11 1st electrode 12 2nd electrode 13 3rd electrode 101,102 Counter electrode 20,21 Resistance 22 AC power supply 23,37 Differential amplifier circuit 24,38 Detection circuit 35,36 Current Detection circuit 51 Metal prism 52, 53 Piezoelectric ceramic thin plate

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-334330 (JP, A) JP-A-61-256217 (JP, A) JP-A-7-283685 (JP, A) 6174 (JP, A) JP-A-6-216701 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01C 19/56 G01P 9/04

Claims (3)

(57) [Claims] 1. A plurality of drive and detection electrodes are formed substantially at the center of a piezoelectric plate having a polarization axis component parallel to the main surface. An even number of electrodes are formed symmetrically with respect to a straight line parallel to the direction of the polarization axis component parallel to the main surface, a first electrode is formed on one main surface, and the first electrode is formed on the other surface. A piezoelectric vibrating gyroscope utilizing an energy confinement vibration mode, wherein a second electrode and a third electrode are formed symmetrically with respect to a straight line facing and parallel to a direction of a polarization axis component parallel to the main surface. 2. A Corioliser which is generated when a driving voltage for excitation is applied to each of the second and third electrodes via a resistor and the piezoelectric plate is rotated around an axis orthogonal to a main surface of the piezoelectric plate. 2. The piezoelectric vibratory gyroscope according to claim 1, wherein a difference between voltages generated at the second and third electrodes by an operation is detected. 3. A first having a virtual grounding function, respectively to the first electrode and the drive electrode, the second and third electrodes
And a second current detection circuit, and the difference between the output voltages of the first and second current detection circuits is caused by the action of Coriolisa that occurs when the piezoelectric plate is rotated about an axis perpendicular to the main surface. 2. The piezoelectric vibratory gyroscope according to claim 1, wherein the piezoelectric vibratory gyroscope is configured to detect the vibration.