JPH10141960A - Piezoelectric oscillation gyro using energy-confinement oscillation mode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and thin-type piezoelectric oscillation gyro which uses an energy confinement oscillation mode. SOLUTION: At, approximately, a center part of the part which comprises a polarization axis on at least one main surface, in thickness direction, of a piezoelectric plate 10, a facing, with a specified interval, first electrode pair 11 and 11', and the second electrode pair 12 and 12' facing each other through the straight line connecting the first electrode pair 11 and 11', are formed. Relating to a piezoelectric oscillation gyro which utilizes an energy confinement oscillation mode wherein one pair of the first electrode pair 11 and 11' and the second electrode pair 12 and 12' is used as a driving electrode pair, with the other a detection electrode pair, each of the detection electrode pair is connected to the input side terminal of a detection transformer 22, and a voltage far excitation is applied between each of the driving electrode pair, and under the condition, the piezoelectric plate 10 is rotated about the axis crossing the main surface, for detecting an output voltage generated between output side terminals of the detection transformer 22.

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, among gyroscopes used for a camera navigation system or a camera-type VTR camera. 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 rotational angular velocity is applied to a vibrating object, a Coriolis force is generated in a direction perpendicular to the vibration direction.

Generally, in a complex vibration system using a vibrator configured to be able to excite and detect vibrations in two different directions orthogonal to each other, when the vibrator is rotated with one of the vibrations being excited, the aforementioned Coriolis Due to the action of the force, a force acts in a direction perpendicular to this vibration, and the other vibration is excited.
Since the magnitude of this vibration is proportional to the amplitude of the input-side vibration and the rotational angular velocity, when the input-side vibration amplitude is constant, the magnitude of the applied rotational angular velocity can be obtained from the magnitude of the output voltage. it can.

FIG. 5 is a perspective view showing a structural example of a vibrator of a conventional piezoelectric vibrating gyroscope. Referring to FIG. 5, the vibrator is formed by joining piezoelectric ceramic thin plates 52 and 53 to approximately the center of each of two adjacent surfaces of a metal prism 51 having a square cross section. 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 5 having a square cross section constituting a vibrator
It is known that 1 has two bending vibration modes that are orthogonal to each other, and that the resonance frequencies of the two bending vibration modes are substantially equal when the characteristics of the material are homogeneous.

Accordingly, when a voltage having a frequency substantially equal to the resonance frequency of the bending vibration of the metal prism 51 is applied to the piezoelectric ceramic thin plate 52, the surface to which the piezoelectric ceramic 52 is bonded becomes uneven (y-axis direction). It bends and vibrates. In this state, when the metal prism 51 is rotated around an axis (z-axis) parallel to the length direction of the metal prism 51 at an angular velocity Ω, the surface of the metal prism 51 to which the piezoelectric ceramic thin plate 53 is bonded is uneven due to the action of Coriolisa. Bending vibration in the direction (x-axis direction) and the piezoelectric effect
Voltage is generated. 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 Ω.

Therefore, if the magnitude of the excitation voltage applied to the piezoelectric ceramic thin plate 52 in the vibrator 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. .

On the other hand, an intermediate frequency filter of an FM radio or a television has an energy trapping vibration type filter as shown in the plan view of FIG. 6 (a), the sectional view of FIG. 6 (b), and the side sectional view of FIG. Is used. The energy trapping vibration is a vibration mode in which the energy of the vibration is concentrated near the drive electrode, and includes longitudinal vibration and sliding vibration of the rectangular piezoelectric plate 61 in the thickness direction, longitudinal vibration and sliding vibration of the piezoelectric plate 61, and the like. There are vibration modes.

Referring to FIGS. 6 (a) and 6 (b), the energy trapping vibration is, for example, as shown in FIG.
Using a piezoelectric plate 61 having a size of 6 mm × 6 mm and a thickness of 0.2 mm, driving electrodes 62, 63, and 64 are formed in a 1.5 mm-diameter region substantially at the center thereof.
In the MHz ceramic filter, as shown in FIG. 7, if hollow portions 66 are formed on both sides of a region having a diameter of about 3 mm around the driving electrodes 62, 63 and 64,
Even if the other parts are fixed with the resin 65, the characteristics of the vibrator are hardly affected. That is, it is possible to obtain a piezoelectric vibrator in which the formation of the lead terminals is free and is not affected by the support, or an energy trapping vibration type filter using the same.

[0010]

In the conventional piezoelectric vibrating gyroscope shown in FIG. 5, a metal prism 51 is used as a vibrator.
The use of the flexural vibration mode of
The fixation must be made at the node of the vibration.

In a conventional piezoelectric vibrating gyroscope,
It was necessary to connect the drive and detection circuits to the electrodes of the vibrator with the lead wires 54 and 55, and it was difficult to suppress variations in characteristics due to variations in the connection state. In addition, drive,
Since the vibrator supported by the holder is mounted on the substrate on which the detection circuit is formed and assembled, it is difficult to form a small and thin piezoelectric vibrating gyroscope.

On the other hand, if the ceramic filter shown in FIG. 6 can be used for a piezoelectric vibrator of a piezoelectric vibrating gyroscope, the problem of small size and thin shape as described above can be solved.

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

[0014]

According to the present invention, at least one main surface of a piezoelectric plate and a substantially central portion of a portion having a polarization component in a thickness direction are opposed to a first portion at a predetermined interval. A second electrode pair is formed so as to face each other via a straight line connecting the electrode pair and the first electrode pair, and one of the first electrode pair and the second electrode pair is formed. In a piezoelectric vibrating gyroscope using an energy trapping vibration mode in which an electrode pair is a driving electrode pair and the other is a detecting electrode pair, each of the detecting electrode pairs is connected to an input side terminal of a detecting transformer, and between the driving electrode pairs. Energy confinement characterized by rotating the piezoelectric plate around an axis crossing the main surface while applying a voltage for excitation, and detecting an output voltage generated between output terminals of the detection transformer. Vibration mode The piezoelectric vibration gyro that uses can be obtained.

According to the present invention, in the piezoelectric vibrating gyroscope utilizing the energy trapping vibration mode, the piezoelectric ceramic is used, and only the vicinity of the region where the first electrode pair and the second electrode pair are formed is used. A piezoelectric vibrating gyroscope utilizing an energy trapping vibration mode characterized by being polarized in the thickness direction can be obtained.

[0016]

Embodiments of the present invention will be described below.

FIG. 1 is a diagram showing a configuration of an energy trap type piezoelectric vibrating gyroscope according to an embodiment of the present invention.
FIG. 2 is a perspective view showing the structure of the piezoelectric vibrator of the energy trap type piezoelectric vibrating gyroscope of FIG.

As shown in FIG. 1, the piezoelectric vibrating gyroscope is
First electrode pair 11, 11 'and second electrode pair 12-12'
And a transformer 2 for detecting
2 is provided.

As shown in FIG. 2, the piezoelectric vibrator 1 has a first piezoelectric plate 10 which has a polarization axis in the thickness direction and is opposed to a substantially central portion of at least one main surface of the rectangular piezoelectric plate 10 at a predetermined interval. And the first electrode pair 11, 11 '
Electrode pair 1 facing the position where ′ is rotated by 90 degrees
2, 12 ′, and the first electrode pair 11, 11 ′ is configured as a drive electrode pair, and the second electrode pair 12, 12 ′ is configured as a detection electrode pair.

Returning again to FIG. 1, the first
The pair of electrodes 11 and 11 ′ are connected to an AC power supply 21, and the second pair of electrodes 12 and 12 ′ are respectively connected to the detecting transformer 2.
2 input side terminals.

On the output side of the detecting transformer 22,
The amplifier circuit 23 and the synchronous detection circuit 24 are connected, and a terminal 25
Is the sensor output of the piezoelectric vibrating gyroscope.

Next, the driving principle of the piezoelectric vibrator shown in FIG.
This will be described with reference to FIG.

FIGS. 3 (a) and 3 (b) are a plan view showing a simplified structure of the piezoelectric vibrator shown in FIGS. 1 and 2, and a cross-sectional view showing only the electrodes, respectively. The basic structure of a pressure oscillator called an energy trapping oscillator is shown.

Referring to FIGS. 3A and 3B, on the same plane in the center of the piezoelectric plate 10 polarized in the thickness direction (z-axis direction), the partial electrodes 14, 15 are formed. Since an electric field is applied to the portion sandwiched between the partial electrodes 14 and 15 in a direction substantially parallel to the plane of the plate (x-axis direction), the electric field interacts with the polarization in the thickness direction perpendicular to the plane. If the dimensions of the partial electrodes 14 and 15 are appropriately designed in accordance with the characteristics of the piezoelectric material used, a parallel electric field excitation type thickness-shear energy trapping vibrator can be formed in this portion. Here, the thickness shear vibration is a 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. 4, when resonance occurs at a half wavelength, a displacement distribution in the thickness direction (z-axis direction) is shown.

Referring back to FIGS. 1 and 2, the first and second electrode pairs 11, 11 'and 12, 12' are arranged so that the lines connecting the centers of the first and second electrode pairs are perpendicular to each other at the centers. Disposing second electrode pairs 11, 11 'and 12, 12';
The second electrode pair 12, 12 'is connected to the input terminal of the detecting transformer. Therefore, the second electrodes 12 and 12 'are free in terms of potential.

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 first electrode pair 11, the first and second electrode pairs 11, 1
In the region surrounded by 1 'and 12, 12', slip vibration in the energy trapping vibration mode in the direction in which the first electrode pairs 11, 11 'face each other occurs. In this state, when the piezoelectric rectangular plate 10 is rotated around an axis perpendicular to the electrode surface, a direction perpendicular to the direction of the excited thickness shear vibration, that is,
The thickness shear vibration occurs in the direction in which the pair of electrodes 12, 12 'face each other.

A voltage is generated between the second electrodes 12 and 12 'by the thickness shear vibration generated by the Coriolis force. Since the magnitude of this voltage is proportional to the applied rotation angular velocity when the excitation voltage is constant, the output voltage of the detection transformer 22 is amplified and synchronous detection is performed at a predetermined timing, so that the applied rotation angular velocity is increased. A proportional output voltage can be obtained.

Therefore, in the present invention, an important point is to excite a clean energy confinement vibration without unnecessary vibration in a region where each electrode pair faces, and particularly when a piezoelectric ceramic is used as the piezoelectric rectangular plate 10. Is the first
By polarizing only the vicinity of the region where the second electrode pairs 11, 11 'and 12, 12' are formed in the thickness direction,
This goal can be achieved.

Further, as a piezoelectric plate, LiNbO ₃ or LiNbO ₃
When a piezoelectric single crystal such as TaO ₃ is used, its spontaneous polarization axis does not necessarily need to be in the thickness direction of the piezoelectric plate, and is suitable for improving temperature characteristics and efficiently exciting vibration in a desired vibration mode. It is also possible to use a piezoelectric plate cut in a suitable cutting envelope.

[0031]

As described above, according to the present invention, the structure is simple, and the input / output terminals can be connected without using lead wires. There is almost no, it is possible to strongly support,
A piezoelectric vibrating gyroscope utilizing an energy trapping vibration mode, which is a small piezoelectric vibrating gyroscope having excellent vibration and shock resistance characteristics, can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of an energy trap type vibrating gyroscope according to an embodiment of the present invention and a circuit connected thereto.

FIG. 2 is a perspective view showing a piezoelectric vibrator of the energy trap type vibrating gyroscope of FIG. 1;

FIG. 3 is a diagram showing a basic configuration for explaining a driving principle of a parallel electric field excitation type thickness-shear mode energy trapping vibrator used in the piezoelectric vibrating gyroscope of FIGS. 1 and 2;
(A) is a plan view and (b) is a cross-sectional view.

4 is a diagram showing a displacement distribution of the thickness-shear mode energy confinement vibrator of FIG. 3;

FIG. 5 is a perspective view showing an example of a vibrator used in a conventional piezoelectric vibrating gyroscope.

6A and 6B are diagrams showing a structure of a conventional energy trapping vibration type filter, wherein FIG. 6A is a plan view and FIG. 6B is a sectional view.

FIG. 7 is a side sectional view showing a support structure of the energy trapping vibration type filter of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric vibrator 10, 61 Piezoelectric plate 11, 11 'First electrode 12, 12' Second electrode 14, 15 Partial electrode 21 Power supply 22 Detection transformer 51 Metal prism 52, 53 Piezoelectric ceramic thin plate 54, 55 Lead terminal 62, 63 drive electrode 64 counter electrode 65 resin 66 cavity

Claims (2)

[Claims] 1. A first electrode pair facing at least one main surface of a piezoelectric plate and substantially at a center of a portion having a polarization component in a thickness direction with a predetermined interval between the first electrode pair and the first electrode pair. The second electrode pair is formed so as to face each other via a straight line connecting the two, and one of the first electrode pair and the second electrode pair is detected as a drive electrode pair and the other is detected. In a piezoelectric vibrating gyroscope using an energy trapping vibration mode configured as an electrode pair, the detection electrode pair is connected to an input terminal of a detection transformer, and a voltage for excitation is applied between the drive electrode pair. A piezoelectric vibrating gyroscope utilizing an energy trapping vibration mode, wherein the piezoelectric plate is rotated around an axis intersecting a main surface to detect an output voltage generated between output terminals of the detecting transformer. 2. A piezoelectric vibrating gyroscope utilizing the energy confinement vibration mode according to claim 1, wherein the piezoelectric ceramic is used, and only a thickness in the vicinity of the region where the first electrode pair and the second electrode pair are formed is thickened. A piezoelectric vibratory gyroscope using an energy trapped vibration mode characterized by being polarized in a direction.