JPH0674773A - Oscillator for oscillation gyro - Google Patents

Abstract

PURPOSE:To enhance detection accuracy of angular speed by stabilizing self- oscillation altitude of an oscillator. CONSTITUTION:Planar parts 16a, 16b having resonance frequencies identical or close to the resonance frequency of an oscillator 3 in the exciting direction are disposed at parts closer to the end part than a position corresponding to a node of the oscillator 3 comprising at least two piezoelectric elements 2a, 2b arranged on the side faces 15a, 15b of a rectangular pillar oscillator 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibrator for a vibrating gyroscope for detecting an angular velocity, and more particularly, it enables highly accurate detection of an angular velocity by stabilizing a vibration posture during self-excited vibration. It is a thing.

[0002]

2. Description of the Related Art Conventionally, as a vibrator for a vibrating gyroscope, there is one as shown in FIG. This conventional vibrator 3 includes a first piezoelectric element 2a on one side surface 1a of the vibrating body 1 having a quadrangular cross section, and a second piezoelectric element 2a on the other side surface 1b adjacent to the side surface 1a. It is configured by sticking the elements 2b, respectively.

In this conventional vibrator 3, on the ridge lines of the vibrating body 1 which oppose each other, the supporting points 4, 5 at positions corresponding to or near the respective nodes of the vibrator 3 are provided.
The supporting strips 6 and 7 are connected to each other, and the supporting strips 6 and 7 are bent in a substantially U shape as a whole.
A vibrating gyro is constructed by fixing both ends of the to one support base 8. Under such a supporting state, the oscillator 3 can be self-oscillated in the X-axis direction of the three-dimensional Cartesian coordinate system, and the Coriolis force is generated due to the rotational movement around the Z-axis. With this, it is possible to vibrate in the Y-axis direction.

By the way, in a vibrating gyroscope using such a vibrator 3, as shown in FIG.
2b is connected to the output side of the driving device 9 via the impedance elements Z ₁ and Z ₂ , respectively, and the capacitive element C is connected to the output side of the driving device 9 via another impedance element Z _3. However, the driving device 9 simultaneously applies an AC voltage to the piezoelectric elements 2a and 2b and the capacitive element C.

Impedance elements Z ₁ and Z ₂ and piezoelectric element
The connection points 10a and 10b with 2a and 2b are connected to the input terminal of the adder 11, and the output terminal of the adder 11 and the connection point 10c between the impedance element Z ₃ and the capacitive element C are differential. It is connected to the input terminal of the amplifier 12, and its differential output is fed back to the driving device 9. Also,
Impedance elements Z _1, Z ₂ and the piezoelectric elements 2a, the connection points 10a and 2b, 10b is also connected to the input terminal of the differential amplifier 13, after the differential output is detected by the synchronous detector 14, It is smoothed by a smoothing circuit (not shown) and is taken out as an angular velocity detection signal. The output of the driving device 9 is also supplied to the synchronous detector 14.

In such a conventional vibrating gyro, by applying an alternating voltage from the driving device 9 to the piezoelectric elements 2a, 2b, the vibrator 3 can be vibrated in the X-axis direction of the three-dimensional orthogonal coordinate system. In this self-excited vibration state,
The output obtained from the connection points 10a and 10b is a combined output of the voltage supplied from the drive device 9 and the voltage output from each piezoelectric element 2a, 2b due to the distortion of each piezoelectric element 2a, 2b. Therefore, if the sum of the two combined outputs is obtained by the adder 11 and the difference between the output and the output corresponding to the supply voltage from the connection point 10c is obtained by the differential amplifier 12, it is based on the vibration in the X-axis direction. Since only the voltage generated from the piezoelectric elements 2a and 2b can be extracted, the output of the differential amplifier 12 is set to the driving device 9
By virtue of being fed back to, the vibrator 3 can be sufficiently stably self-excited.

Further, when the vibrator 3 is rotated around the Z axis while the vibrator 3 is self-excited, the vibrator 3 is moved in the Y axis direction by the Coriolis force proportional to its angular velocity. Vibrating causes a difference between the outputs from the connection points 10a and 10b. Therefore, if the difference is obtained by the differential amplifier 13, the voltage associated with the generation of the Coriolis force can be separated and detected, and the output of the differential amplifier 13 is detected by the synchronous detector 14 and then smoothed. An angular velocity detection signal can be obtained by smoothing with a circuit.

[0008]

In the conventional vibrator 3 as described above, the cross-sectional shape of the vibrating body 1 is set in the X-axis direction and the Y-direction in order to obtain a predetermined sensitivity to Coriolis force.
The shapes are substantially the same over the entire length so that the respective resonance frequencies in the axial direction have the same or close values. However, when the resonance frequencies of the X-axis direction and the Y-axis direction of the vibrator 3 are made equal to or close to each other, the respective vibrations of the X-axis direction and the Y-axis direction are likely to affect each other, and in particular, When the attachment state of the piezoelectric elements 2a, 2b to the vibrating body 1 changes due to a change in the ambient temperature, the self-excited vibration posture of the vibrator 3 changes and the vibration direction includes a vibration component in the Y-axis direction. Therefore, there is a problem that the detection accuracy of the angular velocity is lowered. This invention
It was made paying attention to such problems of the conventional technology, and the self-excited vibration posture of the vibrator is made sufficiently stable,
A vibrator for a vibrating gyroscope capable of detecting an angular velocity with high accuracy.

[0009]

A vibrator for a vibrating gyroscope according to the present invention is a vibrator in which at least two piezoelectric elements are arranged on two mutually different side surfaces of a vibrator having a polygonal cross section. This is characterized in that a plate-shaped portion having a resonance frequency that matches or is close to the resonance frequency in the excitation direction of the vibrator is provided in the portion of the child, which is closer to the end than the position corresponding to the node.

[0010]

This vibrator for a vibrating gyroscope of the present invention basically performs the same function as described in the prior art to perform self-excited vibration, and the piezoelectric element is generated based on the Coriolis force generated according to the angular velocity. A difference in output voltage occurs. Therefore, the angular velocity can be detected by obtaining the difference.
In addition, in this vibrator, the plate-shaped portion provided at the end side from the position corresponding to the node and having a resonance frequency matching or close to the resonance frequency in the excitation direction of the vibrator is When the self-excited vibration is made, it makes a large movement in the exciting direction. For this reason, the oscillator is self-excited as being restricted by the movement of the plate-like portion, and the excitation direction is sufficiently stable. Therefore, the angular velocity can be detected with high accuracy.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the present invention. Here, the vibrating body 15 is formed into a substantially rectangular column shape as a whole.
When the plate-like portions 16a and 16b are formed at the respective end portions of the
The first piezoelectric element 2a is attached to 15a, and the second piezoelectric element 2b is attached to the other side surface 15b adjacent to the side surface 15a to form the vibrator 3. In this case, each of the plate-shaped portions 16a,
16b is located closer to the end than the respective positions corresponding to the two nodes of the vibrator 3. The wide surfaces of the plate-shaped portions 16a and 16b have a width orthogonal to the X-axis direction which is the self-excited vibration direction of the vibrator 3.
Here, the plate thickness t and the length l of the plate-shaped portions 16a and 16b are such that the resonance frequency of the plate-shaped portions 16a and 16b in the X-axis direction matches the resonance frequency of the vibrator 3 in the excitation direction. Alternatively, determine so that the values are close to each other. That is, the plate thickness t and the length l thereof are E, Young's modulus, ρ
Where is the density, the natural frequency of the cantilever shown in Equation 1

[Equation 1] Based on.

The vibrator 3 having the above-described structure is supported on the supporting base by the supporting strips 6 and 7 connected to the vibrator 3 in the same manner as described in the prior art. When AC voltage is applied to the piezoelectric elements 2a and 2b of 3,
The vibrator 3 is largely bent in the X-axis direction and vibrates at its resonance frequency or a vibration frequency close to the resonance frequency to cause self-excited vibration. At this time, a plate-shaped portion having a resonance frequency matching or close to the resonance frequency of the vibrator 3 is generated. 16a and 16b are also transducer 3
Because of the vibration frequency of, the vibration is large in the X-axis direction. Here, since the resonant frequencies of the plate-shaped portions 16a and 16b in the X-axis direction are significantly different from the resonant frequencies of those portions in the Y-axis direction, the above-described X-axis resonance of the plate-shaped portions 16a and 16b is performed. When axially vibrating, they are extremely small, even if they may contain a vibrating component in the Y-axis direction. Thus, the oscillator 3 includes the plate-like portion 16a and
Under the influence of the accurate vibration of 16b in the X-axis direction, the self-excited vibration direction is regulated so that the bending vibration accurately occurs in the X-axis direction. It will always be stable regardless of how it is done. Therefore,
It is possible to sufficiently improve the detection accuracy of the angular velocity.

FIG. 2 is a perspective view showing another embodiment of the present invention, which is a plate-like portion 16a, 16b similar to that described above.
The mass portions 17A and 17b are attached to the tip of the, and the stability of the vibration direction of the vibrator 3 is further enhanced by the mass effect of these mass portions 17a and 17b. Although the present invention has been described above based on the illustrated example, the cross-sectional shape of the vibrating body may be a polygonal shape other than a quadrangle, and the plate-shaped portion may be formed only on one end portion of the vibrating body. It is also possible to provide.

[0014]

Thus, according to the present invention, in particular,
The vibration posture of the vibrator is always stabilized by regulating the self-excited vibration direction of the vibrator by vibrating the plate-shaped part that has a resonance frequency that matches or is close to the resonance frequency of the vibrator. Can be effectively improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a perspective view showing another embodiment of the present invention.

FIG. 3 is a diagram showing a conventional example.

[Explanation of symbols]

 2a, 2b Piezoelectric element 3 Vibrator 4,5 Support point 6,7 Support strip 8 Support stand 15 Vibrator 15a, 15b Side surface 16a, 16b Plate-like part 17a, 17b Mass part

Claims (1)

[Claims] 1. A vibrator in which at least two piezoelectric elements are arranged on mutually different side surfaces of a vibrating body having a polygonal cross-sectional shape, the vibrator being located at a position corresponding to a node. In the part near the edge,
A vibrator for a vibrating gyroscope, wherein a plate-shaped portion having a resonance frequency that matches or is close to the resonance frequency in the excitation direction of the vibrator is provided.