JPH04331312A - Piezoelectric vibrator and piezoelectric vibration gyroscope - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric vibration gyroscope of which an output error at the time when piezoelectric vibration 2 is non-rotatory is lessened, by improving the dimensional precision of a mutual distance between strip- shaped electrodes. CONSTITUTION:A piezoelectric vibrator is formed by providing a plurality of grooves 12 on the outer peripheral surface of a piezoelectric ceramic column 11 so that they divide the outer peripheral surface equally and are parallel to the length direction of the piezoelectric ceramic column 11. A strip-shaped electrode 13 is formed in either one of the grooves 12 in a plurality and a plurality of remaining parts of the outer peripheral surface left after formation of the grooves 12 in a plurality.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to attitude control of moving bodies such as ships and automobiles, and equipment mounted on these moving bodies.
This invention relates to a piezoelectric vibrating gyroscope used in navigation systems for moving objects.

0002

2. Description of the Related Art A piezoelectric vibrating gyroscope utilizes the phenomenon that when rotational acceleration is applied to a vibrating object, a Coriolis force is generated in a direction perpendicular to the direction of the vibration. In other words, using a piezoelectric vibrator configured to be able to excite vibrations in two different orthogonal directions, when one (input side) of the piezoelectric vibrator is excited and the piezoelectric vibrator is rotated, the vibration is perpendicular to the direction of vibration. Coriolis force acts in one direction, and vibrations on the other side (output side) are excited. The magnitude of this vibration on the output side is
It is proportional to the magnitude of vibration on the input side 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 determined 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. 4(a), this piezoelectric vibrator has strip-shaped electrodes 42 printed and formed on the outer peripheral surface of a piezoelectric ceramic cylinder 41, dividing the outer peripheral surface into equal parts in the circumferential direction and parallel to the longitudinal direction of the cylinder 41. There is. The piezoelectric ceramic cylinder 41 is polarized using an electrode 42. This piezoelectric ceramic cylinder 41
A cross section of is shown in FIG. 4(b), and the state of polarization treatment is indicated by an arrow.

As shown in FIG. 5, among the eight strip electrodes of the piezoelectric vibrator 40, a strip electrode 52 adjacent to a strip electrode 51
and the strip electrode 53 are connected, and the strip electrode 51 and the strip electrode 5 are connected.
2 and 53, vibration in the direction of arrow A is excited. When the frequency of the alternating voltage is made approximately equal to the resonance frequency of the bending vibration mode of the piezoelectric ceramic cylinder 41, 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 in bending motion in this manner, a Coriolis force is generated in a direction perpendicular to the direction of arrow A. As a result, a potential difference proportional to the Coriolis force (applied rotational angular velocity) is generated between the strip electrode 54 and the strip electrode 55. This potential difference is amplified by a differential amplifier 56 and used as the output of the piezoelectric vibrating gyroscope.

[0006]

However, in conventional piezoelectric vibrators, strip electrodes are formed on the side surfaces of piezoelectric ceramic cylinders by printing. It is very difficult to print on such a three-dimensional surface with high precision, and when forming band-shaped electrodes that equally divide a piezoelectric ceramic cylinder in the circumferential direction, errors tend to occur in the distance between the electrodes. If there is an error in the distance between the strip electrodes, for example, as shown in FIG.
Even if the same voltage is applied to the two electrodes, there is a difference in the magnitude of each polarization, and there is a problem that an output voltage is generated even when the piezoelectric vibrating gyroscope is not rotating. The present invention improves the dimensional accuracy of the distance between strip electrodes,
An object of the present invention is to provide a piezoelectric vibrating gyroscope that reduces output errors when the piezoelectric vibrating gyroscope is not rotating.

[0007]

[Means for Solving the Problems] According to the present invention, a plurality of grooves are provided on the outer peripheral surface of a piezoelectric ceramic cylinder, dividing the outer peripheral surface into equal parts and parallel to the length direction of the piezoelectric ceramic cylinder. A piezoelectric vibrator is obtained in which a band-shaped electrode is formed on one of the grooves and the plurality of remaining portions of the outer circumferential surface left after forming the plurality of grooves. Furthermore, a piezoelectric vibrating gyroscope including the piezoelectric vibrator subjected to polarization treatment is obtained.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples 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 grooves 12 (eight in this case) are provided on the outer peripheral surface of a piezoelectric ceramic cylinder 11. These grooves 12 are provided parallel to the length direction of the cylinder 11 at positions that equally divide the outer peripheral surface of the piezoelectric ceramic cylinder 11 in the circumferential direction. Further, a strip-shaped electrode 13 is formed in each groove 12 along the respective groove.

Since the piezoelectric ceramic cylinder 11 is usually formed by extrusion molding, the grooves 12 can be easily formed by changing the cross-sectional shape of the die of the molding machine. Further, since the cross-sectional shape of the cap can be formed with high precision, the distances between the grooves 12 can be set at equal intervals with high precision. In other words, the distances between the electrodes 13 formed in this groove can also be made accurately and equally spaced.

Similar to the prior art, this piezoelectric vibrator 10 is also subjected to polarization treatment using the formed electrodes 13 as shown by the arrows in FIG. 1(b). Since the distances between the electrodes are equal, polarization is performed evenly by applying the same voltage to every other electrode.

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. A band-shaped electrode 23 is formed on the remaining portion of the outer peripheral surface (portion other than the groove). Furthermore, the piezoelectric ceramic cylinder is polarized using the strip electrode 23. In this embodiment as well, since the band-shaped electrodes 23 are formed along the remaining portion of the outer circumferential surface, the distances between them are precisely equal. Therefore, polarization occurs evenly.

Using the piezoelectric vibrator 10 of FIG. 1 as an example, a method of using the piezoelectric vibrator of the present invention will be explained. As shown in FIG. 3, a strip electrode 31 of the strip electrodes 12 of the piezoelectric vibrator 10
When the adjacent strip electrodes 32 and 33 are connected and an AC voltage is applied between the strip electrodes 31 and the strip electrodes 32 and 33, vibration in the direction of arrow A is excited. When the frequency of the alternating voltage is made approximately equal to the resonance frequency of the bending vibration mode of the piezoelectric ceramic cylinder 11, the piezoelectric ceramic cylinder 11 bends and vibrates in the direction of arrow A.

When the piezoelectric ceramic cylinder 11 is rotated about the central axis of the cylinder 11 while the piezoelectric vibrator 10 is being subjected to bending vibration in this manner, a Coriolis force is generated in a direction perpendicular to the direction of arrow A. . As a result, the strip electrode 3
4 and the strip electrode 35, a potential difference proportional to the Coriolis force (applied rotational angular velocity) is generated. This potential difference is amplified by a differential amplifier 36 to obtain the output of the piezoelectric vibrating gyro.

In this embodiment, the electrodes are formed so that the distance between the electrodes is precisely equal, and polarization is performed evenly, so that when no rotational angular acceleration is applied to the piezoelectric vibrator, the piezoelectric vibrating gyro The output is theoretically "0". In reality, it can be brought closer to "0" by making the material properties of piezoelectric ceramics homogeneous. In addition,
Although the above embodiment describes the case where eight strip electrodes are created, the number of electrodes is not limited to this.

[0015]

[Effects of the Invention] According to the present invention, a plurality of grooves are provided with high dimensional accuracy when extrusion molding a piezoelectric ceramic cylinder, so that a band-shaped electrode can be formed with high precision by using the grooves. Since polarization can be performed evenly, output errors when the piezoelectric vibrator is not rotating can be reduced, and measurement accuracy of the piezoelectric vibrating gyroscope can be improved.

[Brief explanation of drawings]

FIG. 1 shows a first embodiment of the present invention, in which (a) is a perspective view and (b) is a cross-sectional view.

FIG. 2 shows a second embodiment of the present invention, in which (a) is a perspective view and (b) is a cross-sectional view.

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

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

5 is a circuit diagram of a piezoelectric vibrating gyroscope using the piezoelectric vibrator of FIG. 4. FIG.

[Explanation of symbols]

10, 20, 40 piezoelectric vibrator 11, 21,
41 Piezoelectric ceramic cylinder 12, 22,
groove

Claims (2)

[Claims] 1. A plurality of grooves are provided on the outer circumferential surface of a piezoelectric ceramic cylinder, dividing the outer circumferential surface into equal parts and parallel to the length direction of the piezoelectric ceramic cylinder, and forming the plurality of grooves and the plurality of grooves. A piezoelectric vibrator characterized in that a band-shaped electrode is formed on one of the plurality of remaining portions of the outer circumferential surface left by the above. 2. The piezoelectric vibrator in which the piezoelectric ceramic cylinder is polarized using the plurality of band-shaped electrodes; A piezoelectric vibration characterized by comprising: an AC power supply that applies an AC voltage with a frequency equal to the resonance frequency of the vibration mode; and a voltage detection unit that detects the voltage of a second predetermined electrode among the plurality of strip electrodes. gyro.