JP2000002541A - Vibration gyro - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration gyro in which a force which makes a vibrator rotate does not occur and detection efficiency of an angular speed is excellent. SOLUTION: At four corners symmetrical to a center of a substrate 14 of a vibrator 12, vibration pieces 16a to 16d are integrally formed so that each width direction extends along a diagonal line of the substrate 14. Further, driving piezoelectric elements 22a to 22d are stuck on a back surface of the substrate 14 corresponding to a part where the vibration pieces 16a to 16d are formed. Further, a detecting piezoelectric element 24 is stuck on both faces of the vibration piece 16. The one pair of driving piezoelectric elements 22a, 22b and the other pair of driving piezoelectric elements 22b, 22d are disposed so that the polarization directions are reversed mutually. For this reason, the one pair of vibration pieces 16a, 16c and the other pair of vibration pieces 16b, 16d are mutually in a reverse phase and vibrate together with the substrate 14 so that they reciprocate to each width direction. And, a Coriolis force bends the vibration piece 16a to a thickness direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibrating gyroscope, and more particularly, to a piezoelectric vibrating gyroscope used for, for example, a car navigation system or a vehicle body posture control system.

[0002]

2. Description of the Related Art FIG. 3 is an illustrative view showing one example of a vibrator used in a conventional vibrating gyroscope. This vibrator 1
As shown in FIG. 3, for example, it includes a substrate 2 having a plane square shape. At the four corners of the substrate 2, vibrating pieces 3a, 3b, 3c, and 3d each having a square cross section are formed integrally so as to extend in a direction orthogonal to the main surface of the substrate 2.
Therefore, the vibrating bars 3 a and 3 c face one diagonal direction of the substrate 2, and the vibrating bars 3 b and 3 d face the other diagonal direction of the substrate 2. Further, driving and detecting piezoelectric elements 4 are attached to a total of eight surfaces on the outer periphery of the vibrating bars 3a to 3d, respectively. And these piezoelectric elements 4
As shown by solid and broken arrows in FIG. 3, the pair of vibrating bars 3a and 3c and the other pair of vibrating bars 3b and 3d are driven so as to oscillate in a tuning fork manner in the opposite directions.
Further, when an angular velocity is applied in this state, Coriolis force is generated, and the vibrating bars 3a to 3d bend in a direction orthogonal to the driving vibration. The angular velocity can be detected by detecting the amount of deflection by the piezoelectric element 4.

FIG. 4 is an illustrative view showing another example of a vibrator used in a conventional vibrating gyroscope. The vibrator 5 includes a disk-shaped substrate 6. The substrate 6 is supported by a support member (not shown) near its center. Near the outer peripheral portion of the substrate 6, rectangular plate-shaped vibrating bars 7a, 7b, 7
c and 7d are formed integrally with the substrate 6. These vibrating reeds 7 a to 7 d are formed such that their respective width directions extend in the diameter direction of the substrate 6 and their longitudinal directions extend in a direction orthogonal to the main surface of the substrate 6. Then, the detecting piezoelectric elements 8 are attached to both main surfaces of at least one vibrating piece 7a.
In the center of the substrate 6, a disk-shaped driving piezoelectric element 9 is provided.
Is affixed. When the driving piezoelectric element 9 is vibrated,
The substrate 6 makes a speaker-like spreading vibration, and accordingly, FIG.
As shown by arrows, the vibrating bars 7a to 7d vibrate in the same direction as viewed from the center of the substrate 6 in the width direction. When an angular velocity is applied in this state, a Coriolis force is generated in a direction orthogonal to the drive vibration, that is, in the thickness direction of the vibrating bars 7a to 7d, and the vibrating bars 7a to 7d bend. The angular velocity can be detected by detecting the bending by the detecting piezoelectric element 8.

[0004]

However, in the vibrator 1 as shown in FIG. 3, the vibrating reeds 3a to 3d are bent in two directions, a driving direction and a detection direction, respectively. It had to be formed in the shape of a square pillar having a square cross section. However, the quadrangular prism-shaped vibrating pieces 3a to 3d having a square cross section are hardly bent as compared with the thin plate-shaped vibrating pieces, so that the vibrator has a small amplitude in both the driving direction and the detecting direction, and the detection efficiency is low. It was bad.

[0005] In the vibrator 5 as shown in FIG.
Since a Coriolis force is generated in the same direction with respect to each of the vibrating bars 7a to 7d, a force for rotating the vibrator 5 in the circumferential direction is generated, so that a torsion force is applied to the support member of the substrate 6. In addition, adverse effects are caused by the reaction force.

[0006] Therefore, a main object of the present invention is to provide a vibrating gyroscope that does not generate a force for rotating the vibrator and has good angular velocity detection efficiency.

[0007]

A vibrating gyroscope according to the present invention comprises a substrate and a plurality of vibrating gyros formed on the substrate such that their width directions extend along straight lines passing through the center of the substrate at positions symmetrical with respect to the center of the substrate. A plate-shaped vibrating piece, a driving means provided on the substrate for vibrating the substrate such that the plurality of vibrating pieces vibrate in respective width directions, and a Coriolis force when an angular velocity is applied in the outer peripheral direction of the substrate A vibrating gyroscope including at least one detecting element provided on at least one vibrating piece for detecting bending of the vibrating piece in a thickness direction, wherein the plurality of vibrating pieces are offset by Coriolis force acting on each of the vibrating pieces as a whole. A vibrating gyroscope that vibrates so as to be driven.

In the vibrating gyroscope according to the present invention, since the driving means is attached to the substrate and the detecting means is attached to the vibrating reed, the area of the detecting means can be increased. Also,
In the driving vibration, the substrate vibrates by bending (warping). At this time, the plate-shaped vibrating piece vibrates in its width direction, that is, the vibrating piece itself reciprocates without bending. Therefore, the detecting means provided on the resonator element does not receive stress due to the drive vibration. As a result, in the vibration gyro, the drive vibration and the detection vibration can be respectively increased, and it is not necessary to remove the component of the drive vibration from the detection signal, and the detection efficiency of the angular velocity can be improved. Moreover, since the plurality of vibrating pieces vibrate so that the Coriolis force acting on each of the vibrating pieces is offset as a whole, no force for rotating the substrate constituting the vibrator is generated, and the supporting material for supporting the substrate is provided. No torsional force is applied. Therefore, a reaction force from the housing as in the related art does not occur.

Further, in the vibrating gyroscope according to the present invention,
The vibrating bar has four symmetrical points with respect to the center of the substrate.
One pair of vibrating bars and the other pair of vibrating bars are formed so as to extend in the width direction on two straight lines that pass through the center of the substrate and are orthogonal to each other, and oppose each other across the center of the substrate. Preferably, it vibrates. In this case, the stress of the driving vibration is not applied to the detecting piezoelectric element, and the Coriolis force acting on each vibrating piece can be offset as a whole.

In the vibrating gyroscope according to the present invention, it is preferable that the driving means is formed on the back side of the portion where the vibrating piece is formed on the substrate, in order to obtain the above-mentioned effects.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention with reference to the accompanying drawings.

[0012]

FIG. 1 is an illustrative view showing one example of a vibrating gyroscope according to the present invention. This vibrating gyro 10
Includes a vibrator 12 formed of a constant elastic metal material such as an elinvar. The vibrator 12 includes, for example, a substrate 14 having a substantially square shape when viewed from a plane. At the four corners symmetrical with respect to the center of the substrate 14, each of the strip-shaped vibrating pieces 16 is formed so that the longitudinal direction extends in a direction orthogonal to the main surface of the substrate 14.
a, 16b, 16c and 16d are integrally formed of the same material as the substrate 14. Moreover, these vibrating bars 16a to 16a
16d is formed so that each width direction extends along a straight line, that is, a diagonal line extending through the center of the substrate 14 to four corners. Since the substrate 14 is substantially square, two diagonal lines are orthogonal to each other through the center of the substrate 14.

At the center of the surface of the substrate 14 on which the vibrating bars 16a to 16d are formed, for example, a cylindrical support member 18 is formed integrally with the substrate 14 using the same material. The other end of the support member 18 is fixed to the housing 20. The material for forming the vibrator 12 is not limited to the elinvar, but may be a material that generally generates mechanical vibration, such as an iron-nickel alloy, quartz, glass, quartz, or ceramics.

On the back surface of the portion where the vibrating bars 16a to 16d are integrally formed on the substrate 14, strip-shaped driving piezoelectric elements 22a to 22d as driving means are provided on the substrate 1 respectively.
4 is attached along the diagonal line. Driving piezoelectric element 22a
Nos. 22d are electrodes formed on both surfaces of a piezoelectric layer polarized in the thickness direction, for example. In this case, the driving piezoelectric elements 22a to 22d face each other diagonally across the center of the back surface of the substrate 14, but are arranged so that the polarization directions are the same as each other. The driving piezoelectric elements 22b and 22d on the other diagonal line are arranged so that the polarization directions are opposite to each other. Therefore, when in-phase drive signals are input to the drive piezoelectric elements 22a to 22d, the drive piezoelectric elements 22a and 22c and the drive piezoelectric elements 22a to 22d are driven.
b and 22d oscillate in opposite phases. Accordingly, the vibrating bar 1 opposing on one diagonal line of the surface of the substrate 14
6a and 16c (hereinafter, referred to as one pair) and the vibrating pieces 16b and 16d (hereinafter, referred to as the other pair) opposing on the other diagonal vibrate together with the substrate 14 so as to reciprocate in the respective width directions in opposite phases. .

Further, a detecting piezoelectric element 24 as a detecting means is attached to both surfaces in the thickness direction of the vibrating reed 16a. The detecting piezoelectric element 24 is also formed, for example, by forming electrodes on both surfaces of a piezoelectric body polarized in the thickness direction.

The housing 20 further includes a drive detection circuit 28
Has been fixed. The drive detection circuit 28 includes the lead 2
6, the driving piezoelectric elements 22a to 22d and the detecting piezoelectric element 24 are connected. The support member 18 is connected to a reference electrode of the drive detection circuit 28. The drive detection circuit 28 includes an addition amplification circuit 30 and a phase adjustment circuit 32. The signals from the two detection piezoelectric elements 24 are added and amplified by the addition amplification circuit 30. Addition amplification circuit 3
The output signal of 0 is shifted to a phase that easily oscillates by the phase adjustment circuit 32 to be a drive signal, and is input to the four driving piezoelectric elements 22a to 22d. Therefore, an oscillation loop is formed by the detection piezoelectric element 24, the addition amplification circuit 30, the phase adjustment circuit 32, and the driving piezoelectric elements 22a to 22d. Further, the difference between the signals from the two detecting piezoelectric elements 24 is amplified by the differential amplifier circuit 34, and the output signal thereof is rectified by the rectifier circuit 36, and the vibration gyro 10
Output.

In this vibrating gyroscope 10, one pair of vibrating bars 16a and 16c and the other pair of vibrating bars 16b and 1b are used.
As shown by the solid and dashed arrows in FIG. At this time, when an angular velocity indicated by ω is applied, a Coriolis force is generated in a direction orthogonal to the driving vibration, that is, in a thickness direction of the vibrating bars 16a to 16d. In this direction, the vibrating reed 1
Since the rigidity of 6a to 16d is low, the vibrating bars 16a to 16d bend as indicated by the dashed-dotted arrows. Then, the alternating current signals in the opposite directions are output from the detection piezoelectric elements 24 attached to both surfaces of the resonator element 16a. Therefore, a DC output signal corresponding to the angular velocity can be obtained by amplifying and rectifying these differential outputs.

In the vibrating gyroscope 10, the driving piezoelectric elements 22a to 22d are mounted on the substrate 14, and the detecting piezoelectric elements 24 are mounted on the vibrating pieces 16a to 16d. Can be. Further, the vibrating reeds 16a to 16d vibrate in the respective width directions due to the bending of the substrate 14 at the time of the drive vibration, and bend at the respective thickness directions at the time of the detection vibration. Therefore, the substrate 14 is designed to be easily bent only in the driving and detecting directions.
And, the vibrating pieces 16a to 16d are formed thin. Further, the detecting piezoelectric element 24 is not subjected to the driving vibration stress by the driving piezoelectric elements 22a to 22d. Therefore, in the vibrating gyroscope 10, the driving vibration and the detected vibration can be respectively increased, and it is not necessary to remove the component of the driving vibration from the detection signal, and the detection efficiency of the angular velocity can be improved. Moreover, the vibrating piece 16a of the vibrating gyroscope 10
16 to 16d, the one pair of vibrating bars 16a and 16c and the other pair of vibrating bars 16b and 16d vibrate in opposite phases so as to alternate between inside and outside as viewed from the center of the substrate 14, so that the Coriolis force acting on each of them is offset as a whole. Is done. Therefore, no force for rotating the substrate 14 is generated, and the substrate 1
No torsional force is applied to the supporting member 18 supporting the fourth member 4. Therefore, adverse effects due to the reaction force from the housing 20 are reduced.

Next, a modified example of the above-described vibrating gyroscope 10 will be described. In this modification, although not specifically shown, the above-described vibrator 12 is integrally formed of a piezoelectric material such as a ceramic. Then, drive electrodes are formed in place of the drive piezoelectric elements 22a to 22d as drive means, and detection electrodes are attached in place of the detection piezoelectric elements 24 as detection means. Also, one pair of vibrating bars 16a
In order to vibrate the other pair of vibrating bars 16b and 16d in opposite phases, the pair of vibrating bars 1
6a and 16b and the other pair of vibrating bars 16
The portions corresponding to b and 16d are polarized in the opposite direction. In the case of this modification, since the vibrator 12 is formed of a piezoelectric material, the portion where each electrode is attached functions in the same manner as the piezoelectric element, and the same operation and effect as described above can be obtained.

[0020]

According to the vibrating gyroscope according to the present invention,
Since no force is required to rotate the vibrator, there is no adverse effect due to the reaction force from the housing. In addition, this vibrating gyroscope has good angular velocity detection efficiency.

[Brief description of the drawings]

FIG. 1 is an illustrative view showing one example of a vibrating gyroscope according to the present invention;

FIG. 2 is an illustrative view showing a vibration state of the vibration gyro shown in FIG. 1;

FIG. 3 is an illustrative view showing one example of a conventional vibrating gyroscope;

FIG. 4 is an illustrative view showing another example of the conventional vibrating gyroscope;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vibration gyroscope 12 Vibrator 14 Substrate 16a-16d Vibrating piece 18 Support member 20 Housing 22a-22d Drive piezoelectric element 24 Detection piezoelectric element 26 Lead wire 28 Drive detection circuit 30 Addition amplification circuit 32 Phase adjustment circuit 34 Differential amplification Circuit 36 Rectifier circuit

Claims (3)

[Claims] A substrate, a plurality of plate-shaped vibrating reeds formed on the substrate such that respective width directions extend along a straight line passing through the center of the substrate at symmetrical positions with respect to the center of the substrate; A driving unit provided on the substrate for vibrating the substrate so that the plurality of vibrating pieces vibrate in respective width directions; and a thickness of the vibrating piece due to Coriolis force when an angular velocity is applied in an outer peripheral direction of the substrate. A vibrating gyroscope including at least one of the vibrating reeds for detecting deflection in a direction, wherein the plurality of vibrating reeds cancel out Coriolis forces acting on the respective vibrating reeds as a whole. Vibrating gyroscope that vibrates like driving. 2. The vibrating reed is formed so as to extend in the width direction on two straight lines passing through the center of the substrate and orthogonal to each other at four positions symmetrical with respect to the center of the substrate. The vibrating gyroscope according to claim 1, wherein one pair of the vibrating pieces and the other pair of the vibrating pieces opposing each other are driven and vibrated in opposite phases. 3. The vibrating gyroscope according to claim 1, wherein the driving unit is formed on a back side of a portion where the vibrating piece is formed on the substrate.