JPH08261762A - Vibration gyro - Google Patents

Abstract

PURPOSE: To provide a vibration gyro capable of being stable in characteristic even when the ambient temperature is varied. CONSTITUTION: The device comprises a vibrator 2 having the shape of a right triangular prism and support members 4 fixed to the vibrator 2 in the vicinity of a node point. Each of the support members 4 consists of a pair of leg sections 5, 5 each one end is respectively fixed to an attachment board 7 and connection section 6 that connects the other ends of the leg sections 5, 5 to each other. The leg sections are made longer such that freedom of the vibration in the direction of an axis of the vibrator 2 is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration gyro, and more specifically, it detects a position of a moving body by detecting a rotational angular velocity, a navigation system for performing appropriate guidance, or an external vibration. The present invention relates to a vibration gyro that can be applied to an anti-vibration system such as an image stabilization device that performs appropriate vibration control.

[0002]

2. Description of the Related Art FIG. 4 is a perspective view of an essential part of an example of a conventional vibrating gyro, which is the background of the present invention. The vibrating gyroscope 31 includes a substantially triangular prism-shaped vibrator 32 made of a constant elastic metal, and substantially rectangular piezoelectric elements 33a, 33b, 33c are attached to the center of each side surface of the vibrator 32 with an adhesive. Has been done. Of these, the piezoelectric elements 33a and 33b are used for driving and detecting an output signal,
3c is used for returning. Then, the piezoelectric element 33
A drive circuit (not shown) including an oscillation circuit and a phase circuit is connected as a feedback loop for self-oscillating the vibrator 32 between the piezoelectric elements 33a and 33b. A detection circuit (not shown) including a differential amplifier circuit is connected to the.

In this vibrating gyroscope 31, when a driving signal is applied from the feedback piezoelectric element 33c to the driving piezoelectric elements 33a and 33b, the vibrator 32 flexurally vibrates in the primary vibration mode. When rotation about the axis of the oscillator 32 is applied in this state, the vibration direction of the oscillator 32 changes due to the Coriolis force. Therefore, an output difference corresponding to the rotation speed occurs between the piezoelectric elements 33a and 33b, and the rotation angular speed can be detected by signal processing the output difference by the detection circuit.

Further, in this vibrating gyroscope 31, in order to prevent the bending vibration of the vibrator 32 from being hindered, the vibration
Near the node points in the next vibration mode, substantially U-shaped support members 34, 34 made of a thin wire having a high elastic modulus are fixed. That is, the piezoelectric element 33a of the vibrator 32,
In the ridgeline portion sandwiched by 33b, the support members 34, 34 are fixed to the entire length 1 of the vibrator 32 at a position of about 0.224l from both end surfaces of the vibrator 32. Then, by fixing the ends of the supporting members 34, 34 to one main surface of the mounting substrate 37 in the shape of a strip made of glass epoxy material or the like, the oscillator 32 is attached to the mounting substrate 37 via the supporting members 34, 34. It is attached.

By the way, the bending vibration of the vibrator 32 of the vibration gyro 31 is actually a combined vibration of the fundamental vibration of the first-order vibration mode and a plurality of harmonic components having a frequency that is an integral multiple thereof. . Therefore, as shown in FIG. 5, the vibrator 32 vibrates not only in the first-order vibration mode A but also in the third-order vibration mode B, for example. In this case, the support member 34,
The position C to which 34 is fixed is a node portion of vibration in the first-order vibration mode A, but is substantially an antinode portion of vibration in the third-order vibration mode B. Therefore, the support members 34, 34 do not hinder the fundamental vibration of the first vibration mode, but they do not hinder the higher harmonics of the third vibration mode. However, since the vibration gyro 31 detects the rotational angular velocity by utilizing the fundamental vibration of the oscillator 32, and since these harmonic components are extremely small compared to the fundamental vibration, the vibration gyro 31 is supported by the oscillator 32. It can be said that the fixing positions of the members 34, 34 are proper.

[0006]

However, these harmonic components have a considerable influence on the temperature characteristics of the vibration gyro 31. That is, when the ambient temperature changes, due to the processing accuracy of the vibrator 32, the shape error of the piezoelectric element, the deviation of the bonding position, and the like, the side surface L side of the vibrator 32 to which the piezoelectric element 33a is bonded, On the side surface R side to which the piezoelectric element 33b is bonded, the balance of impedance frequency characteristics and the like is lost, and a difference occurs in the amplitude and phase of the outputs of the piezoelectric elements 33a and 33b. Bring drift. At this time, as shown in FIG. 6, the resonance frequency D of the fundamental vibration of the primary vibration mode
Since the difference in impedance variation between the side surface L side and the side surface R side is more prominent near the resonance frequency E of the higher harmonic of the third vibration mode than in the vicinity thereof, the higher harmonic of the third vibration mode exerts The impact is relatively large.

The inventors of the present invention have impedances on the side surface L side and the side surface R side closer to the resonance frequency E of the harmonic of the third vibration mode than to the resonance frequency D of the fundamental vibration of the first vibration mode. As a cause of the remarkable difference in the fluctuation of the above, attention was paid to the support structure of the vibrator 32. Then, the support members 34, 3
It was found that 4 is one of the causes that the degree of freedom of the harmonic component, especially the degree of freedom in the axial direction of the oscillator 32 is obstructed.

Therefore, a main object of the present invention is to provide a vibrating gyroscope whose characteristics are stable even with a change in ambient temperature by increasing the degree of freedom of the support member with respect to vibration in the axial direction of the vibrator. It is to be.

[0009]

In order to achieve the above object, the present invention provides a vibrating gyroscope comprising a columnar vibrator and a support member fixed near a node point of the vibrator. The member is characterized in that the member has a degree of freedom with respect to the vibration of the vibrator in the axial direction.

[0010]

According to the above structure, since the supporting member maintains the degree of freedom with respect to the vibration of the vibrator in the axial direction, the flexural vibration of the vibrator, in particular the harmonic component thereof, can be brought closer to the free vibration. .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. 1 is a side view of a vibrating gyroscope according to a first embodiment of the present invention, and FIG. 2 is a circuit diagram thereof. The vibration gyro 1 includes a vibrator 2. The vibrator 2 is made of, for example, a constant elastic metal such as elinvar, or a material that generally causes mechanical vibration such as quartz, glass, crystal, or ceramic, and has a length of about 40.0 mm and a side of about 3.5 mm in a substantially regular triangular prism shape. It is formed. Piezoelectric elements 3a, 3b, 3c are formed on each side surface of the vibrator 2. Piezoelectric element 3
a, 3b and 3c have a width of about 2.0 mm and a length of about 5.0 m
Electrodes are formed on both sides of a piezoelectric ceramic having a thickness of m and a thickness of about 0.2 mm, and one of these electrodes is bonded to the side surface of the vibrator 2 with an adhesive or the like. Among them, the piezoelectric elements 3a and 3b are used for driving and detecting an output signal,
c is used for returning. Then, the piezoelectric elements 3a,
A drive circuit 11 including an oscillation circuit and a phase circuit is connected as a feedback loop for causing the vibrator 2 to self-oscillate between the piezoelectric elements 3a and 3b. The detection circuit 12 formed of a circuit is connected.

In this vibration gyro 1, when a driving signal is applied from the feedback piezoelectric element 3c to the driving piezoelectric elements 3a and 3b, the vibrator 2 flexurally vibrates in the primary vibration mode.
When rotation about the axis of the vibrator 2 is applied in this state, the vibration direction of the vibrator 2 is changed by the Coriolis force.
Therefore, an output difference corresponding to the rotation speed occurs between the piezoelectric elements 3a and 3b. Then, the output angular difference is calculated by the differential amplifier circuit of the detection circuit 12, and the differential voltage is subjected to signal processing and taken out as an angular velocity detection signal, whereby the rotational angular velocity can be detected.

In addition, in this vibrating gyro 1, the vibrator 2
In order not to hinder the flexural vibration of the support member 4, the support members 4 and 4 are fixed near the node point in the primary vibration mode of the vibrator 2. That is, at the ridgeline portion of the vibrator 2 sandwiched by the piezoelectric elements 3a and 3b, the support members 4 and 4 are fixed to the entire length 1 of the vibrator 2 at positions of about 0.224l from both end surfaces of the vibrator 2. . The supporting members 4 and 4 are made of a thin wire material having a high elastic modulus such as tungsten,
It is composed of a pair of legs 5 and 5, and a connecting portion 6 that connects between the upper ends of the legs 5 and 5. Then, the central portion of the connecting portion 6 is fixed to the vibrator 2 by, for example, welding, and the leg portions 5,
The lower end of 5 is fixed to one main surface of a substantially strip-shaped mounting substrate 7 made of a glass epoxy material or the like by soldering or the like, whereby the vibrator 2 is mounted on the mounting substrate 7 via the supporting members 4 and 4.
Attached to.

In the vibrating gyro 1 as described above, conventionally, the length of the leg portion and the connecting portion of the supporting member are each about 6.0 mm, but here, only the length of the leg portions 5 and 5 is about 9. It has been extended to 0.0 mm. Therefore, the distance between the lower end serving as the fulcrum of the leg portions 5 and 5 and the upper end serving as the force point is extended, and the leg portions 5 and 5 are easily bent.
The degree of freedom with respect to the vibration of the vibrator 2 in the axial direction at is increased. As a result, the bending vibration of the vibrator 2, especially 1
It is possible to bring harmonic components other than the fundamental vibration of the next vibration mode closer to free vibration. Although the length of the leg portions 5 and 5 of the support member 4 is set to about 9.0 mm here, if the length of the leg portions 5 and 5 is too long, the supporting strength decreases.
The length of the legs 5, 5 is preferably about 9.0 to 10.0 mm.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The vibrating gyroscope 21 of the second embodiment has a central portion of substantially linear support members 24, 24 made of a thin wire material having a high elastic modulus, such as tungsten, in the vicinity of a node point in the first vibration mode of the vibrator 2. Are fixed, for example, by welding. The vibrator 2 is arranged between the pair of wall portions 28, 28 which stand upright on both side edges in the width direction of the substantially strip-shaped mounting substrate 27,
Walls 28 and 2 where both ends of the support members 24 and 24 are fixed portions
The vibrator 2 is fixed to the upper end of the mounting substrate 2 by soldering or the like, so that the vibrator 2 is mounted on the mounting substrate 2 via the supporting members 24, 24.
It is attached to 7.

In such a vibrating gyro 21, the conventional
The length of the support members 24, 24 was set to about 12.0 mm, but here, it is extended to about 20.0 mm. Therefore, the distance between the both ends, which are fulcrums of the supporting members 24, 24, and the fixing portion of the vibrator 2, which is the force point, is extended, and the supporting member 2
The support members 24, 24 are easily deformed.
The degree of freedom with respect to the axial vibration of the vibrator 2 at 24 is increased. Thereby, the flexural vibration of the vibrator 2, in particular, the harmonic components other than the fundamental vibration of the first vibration mode can be brought closer to the free vibration. Here, the length of the legs 5, 5 of the support member 4 is set to about 20.0 mm, but if the length of the support members 24, 24 is too long, the support strength decreases, so that the support members 24, 24 have Length is about 20.0
It is preferably about 25.0 mm.

The vibrating gyroscope 1 of the first embodiment as described above.
In the vibrating gyroscope 21 of the second embodiment, the length of the legs of the substantially U-shaped support member is about 6.0 mm, and other portions are the same as those of the vibrating gyroscope 1 of the first embodiment. The temperature drift and the variation in the sensitivity temperature characteristic can be improved by about 20% as compared with the vibration gyro.

In the vibrating gyroscope of each of the above-mentioned embodiments, a substantially triangular prism-shaped vibrator is used. However, the shape of the vibrator may be another triangular prism, a polygonal prism such as a square prism, or a cylinder. Well, it is not particularly limited. The number of piezoelectric elements is not limited to three, and the number of piezoelectric elements may be increased or decreased as necessary.

[0019]

As described above, according to the vibrating gyroscope of the present invention, the flexural vibration, especially the harmonic component thereof can be brought closer to the free vibration, so that the vibration can be prevented even when the ambient temperature changes. It is possible to improve the impedance variation in the vicinity of the resonance frequency of the higher harmonic component of the child and stabilize the characteristics of the vibration gyro.

[Brief description of drawings]

FIG. 1 is a perspective view of essential parts showing a vibrating gyroscope according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of the vibration gyro shown in FIG.

FIG. 3 is a perspective view of essential parts showing a vibrating gyroscope according to a second embodiment of the present invention.

FIG. 4 is a perspective view of a main part of a conventional vibrating gyro.

FIG. 5 is an explanatory diagram showing a vibration mode of a vibrator.

FIG. 6 is an explanatory diagram showing impedance frequency characteristics of a vibrator.

[Explanation of symbols]

 1 Vibration Gyro 2 Vibrator 3a Piezoelectric Element 3b Piezoelectric Element 3c Piezoelectric Element 4 Supporting Member 5 Legs 6 Connecting Part 7 Mounting Board

Claims (1)

[Claims] 1. A vibrating gyroscope comprising a columnar vibrator and a support member fixed near a node point of the vibrator, wherein the support member has a degree of freedom with respect to vibration of the vibrator in an axial direction. A vibrating gyro that is characterized by being kept.