JP2597248B2 - Piezoelectric vibrator and piezoelectric vibratory gyroscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to mobile units such as ships and automobiles, and attitude control of equipment mounted on these mobile units.
The present invention relates to a piezoelectric vibratory gyroscope used for a navigation system of a moving body.

[0002]

2. Description of the Related Art A piezoelectric vibrating gyroscope utilizes a phenomenon that when a rotating object is given a rotational acceleration, a Coriolis force is generated in a direction perpendicular to the vibration direction. That is, when a piezoelectric vibrator configured to be able to excite vibrations in two different directions perpendicular to each other is rotated while one (input side) of the piezoelectric vibrator is excited, a direction perpendicular to the direction of the vibration is obtained. The Coriolis force acts in a certain direction, and the other (output side) vibration is excited. The magnitude of the output-side vibration is proportional to the magnitude of the input-side vibration and the rotational angular velocity. Therefore, if the magnitude of the vibration (input voltage) on the input side is kept constant, the magnitude of the rotational angular velocity can be obtained from the magnitude of the vibration (output voltage) on the output side.

A conventional piezoelectric vibrating gyroscope has a piezoelectric vibrator 40 as shown in FIG. As shown in FIG. 4A, the piezoelectric vibrator is formed by printing a strip-shaped electrode 42 parallel to the longitudinal direction of the cylinder 41 on the outer peripheral surface of the piezoelectric ceramic cylinder 41 by equally dividing the outer peripheral surface in the circumferential direction. I have. The piezoelectric ceramic cylinder 41 is subjected to a polarization process using the electrode 42. This piezoelectric ceramic cylinder 4
1B is shown in FIG. 4B, and the state of the polarization treatment is indicated by arrows.

As shown in FIG. 5, a strip electrode 52 adjacent to a strip electrode 51 among eight strip electrodes of a piezoelectric vibrator 40 is used.
And the strip-shaped electrode 53, and the strip-shaped electrode 51 and the strip-shaped electrode 5 are connected.
When an AC voltage is applied between the electrodes 2 and 53, vibration in the direction of arrow A is excited. When the frequency of the AC voltage is substantially equal to the resonance frequency of the piezoelectric ceramic cylinder 41 in the bending vibration mode, the piezoelectric ceramic cylinder 41 bends and vibrates in the direction of arrow A.

[0005] When the piezoelectric ceramic cylinder 41 is rotated about the axis of the cylinder 41 as the center of rotation while the piezoelectric vibrator is bent in this manner, a Coriolis force is generated in a direction perpendicular to the arrow A direction. As a result, a potential difference proportional to the Coriolis force (the applied rotational angular velocity) is generated between the strip electrodes 54 and 55. This potential difference is amplified by the differential amplifier 56 and used as the output of the piezoelectric vibrating gyroscope.

[0006]

However, in the conventional piezoelectric vibrator, the band-shaped electrodes are formed on the side surfaces of the piezoelectric ceramic cylinder by printing. It is very difficult to accurately print on such a three-dimensional surface, and the formation of strip electrodes that equally divide the piezoelectric ceramic cylinder in the circumferential direction tends to cause an error in the distance between them. If there is an error in the distance between the strip electrodes, when performing the polarization process, for example, as shown in FIG.
Even if the same voltage is applied to one electrode, there is a problem that a difference occurs in the magnitude of each polarization and an output voltage is generated in a state where the piezoelectric vibrating gyroscope is not rotating. The present invention improves the dimensional accuracy of the distance between the strip electrodes,
An object of the present invention is to provide a piezoelectric vibrating gyroscope in which an output error when the piezoelectric vibrating gyroscope is not rotating is reduced.

[0007]

According to the present invention, on the outer peripheral surface of a piezoelectric ceramic cylinder, a plurality of grooves are provided which equally divide the outer peripheral surface and are parallel to the length direction of the piezoelectric ceramic cylinder. A piezoelectric vibrator is obtained in which a band-shaped electrode is formed on any one of the groove and the plurality of remaining portions of the outer peripheral surface left by forming the plurality of grooves. Further, a piezoelectric vibrating gyroscope having the above-described piezoelectric vibrator subjected to the polarization processing can be obtained.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. In the piezoelectric vibrator 10 of this embodiment, a plurality of (here, eight) grooves 12 are provided on the outer peripheral surface of a piezoelectric ceramic cylinder 11. These grooves 12 are provided at positions that equally divide the outer peripheral surface of the piezoelectric ceramic cylinder 11 in the circumferential direction and are parallel to the length direction of the cylinder 11. In each groove 12, a strip-shaped electrode 13 is formed along each groove.

Usually, since the piezoelectric ceramic cylinder 11 is formed by extrusion, the groove 12 can be easily formed by changing the cross-sectional shape of the die of the forming machine.
In addition, since the cross-sectional shape of the die can be created with high accuracy, the distance between the grooves 12 can be made equal with high accuracy. That is, the distance between the electrodes 13 formed in the groove can also be accurately made equal.

The piezoelectric vibrator 10 is also subjected to a polarization process as shown by an arrow in FIG. Since the distance between the electrodes is equal, if the same voltage is applied to every other electrode, polarization is performed without bias.

FIG. 2 shows a second embodiment of the present invention. In this piezoelectric vibrator 20, a groove 22 is formed in a piezoelectric ceramic cylinder 21 as in the first embodiment. The strip-shaped electrode 23 is formed on the remaining portion (the portion other than the groove) of the outer peripheral surface. Further, the polarization treatment of the piezoelectric ceramic cylinder is performed by using the strip electrode 23. Also in this embodiment, since the strip-shaped electrodes 23 are formed along the remaining portion of the outer peripheral surface, the distance between the strip-shaped electrodes 23 becomes equal with high accuracy. Therefore, polarization is performed evenly.

A method of using the piezoelectric vibrator of the present invention will be described with reference to the piezoelectric vibrator 10 shown in FIG. 1 as an example. As shown in FIG. 3, among the strip electrodes 12 of the piezoelectric vibrator 10, the strip electrodes 3
Connecting the strip electrode 32 and the strip electrode 33 adjacent to each other,
When an AC voltage is applied between the strip electrode 31 and the strip electrodes 32 and 33, vibration in the direction of arrow A is excited. If the frequency of the AC voltage is substantially equal to the resonance frequency of the piezoelectric ceramic cylinder 11 in the bending vibration mode, the piezoelectric ceramic cylinder 11 bends and vibrates in the direction of arrow A.

When the piezoelectric ceramic cylinder 11 is rotated about the center axis of the cylinder 11 in the state where the piezoelectric vibrator 10 is bent and vibrated in this manner, a Coriolis force is generated in a direction perpendicular to the arrow A direction. . Thereby, the strip electrode 3
A potential difference proportional to the Coriolis force (the applied rotational angular velocity) is generated between the electrode 4 and the strip electrode 35. This potential difference is amplified by the differential amplifier 36 to obtain the output of the piezoelectric vibrating gyroscope.

In the present embodiment, the electrodes are formed so that the distance between the electrodes becomes equal with high accuracy, and the polarization is performed uniformly. Therefore, when the rotational angular acceleration is not applied to the piezoelectric vibrator, the piezoelectric vibrating gyroscope is not used. The output is theoretically "0". Actually, it is possible to approach “0” by making the material characteristics of the piezoelectric ceramics uniform. In the above embodiment, the case where eight strip electrodes are formed has been described, but the number of electrodes is not limited to this.

[0015]

According to the present invention, when extruding a piezoelectric ceramic cylinder, a plurality of grooves are provided with high dimensional accuracy, so that band electrodes can be formed with high accuracy by using the grooves. Since polarization can be performed evenly, an output error when the piezoelectric vibrator is not rotating can be reduced, and the measurement accuracy of the piezoelectric vibrating gyroscope can be improved.

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment of the present invention, wherein FIG. 1A is a perspective view and FIG.

FIGS. 2A and 2B show a second embodiment of the present invention, wherein FIG. 2A is a perspective view and FIG.

FIG. 3 is a circuit diagram of a piezoelectric vibrating gyroscope using the piezoelectric vibrator of FIG. 1;

FIG. 4 shows a conventional piezoelectric vibrator, wherein (a) is a perspective view,
(B) is a cross-sectional view.

FIG. 5 is a circuit diagram of a piezoelectric vibrating gyroscope using the piezoelectric vibrator of FIG.

[Explanation of symbols]

 10, 20, 40 Piezoelectric vibrator 11, 21, 41 Piezoelectric ceramic cylinders 12, 22, Grooves 13, 23, 42 Strip electrodes 31, 32, 33, 34, 35 Strip electrodes 51, 52, 53, 54, 55 Strip electrodes 36,56 differential amplifier

Claims (2)

(57) [Claims] 1. A method of forming a plurality of grooves on an outer peripheral surface of a piezoelectric ceramic cylinder by dividing the outer peripheral surface into equal parts and providing a plurality of grooves parallel to a length direction of the piezoelectric ceramic cylinder. A piezoelectric vibrator characterized in that a band-shaped electrode is formed on any one of a plurality of remaining portions of the outer peripheral surface left by the above. 2. A method according to claim 1, wherein a plurality of grooves are formed on an outer peripheral surface of the piezoelectric ceramic cylinder, the plurality of grooves being equally divided from the outer peripheral surface and being parallel to a length direction of the piezoelectric ceramic cylinder. Among the plurality of remaining portions of the outer peripheral surface left by forming a band-shaped electrode on any one, a piezoelectric vibrator that has been subjected to a polarization process on the piezoelectric ceramic cylinder using the plurality of band-shaped electrodes, An AC power supply for applying an AC voltage having a frequency equal to a resonance frequency of a bending vibration mode of the piezoelectric ceramic cylinder to a first predetermined electrode of the plurality of strip electrodes; and a second predetermined electrode of the plurality of strip electrodes And a voltage detector for detecting the voltage of the piezoelectric vibrating gyroscope.