JPH06117862A - Vibrator - Google Patents

Abstract

PURPOSE:To obtain a vibrator which is suitable for mass production and has high measurement accuracy by only detecting the rotational torque generated by the Coriolis force of tuning forks integrally formed with a detecting section. CONSTITUTION:Tuning forks 1 and 2 are arranged on both sides of the connecting section 3 of an integrally formed vibrator and base sections of the forks 1 and 2 are arranged on one end side of the section 3. In detecting sections 4 and 5 arranged on the other end side of the section 3, electrodes constituted of metallic films of gold, etc., by vapor deposition are provided. When an angular velocity omega is applied to the vibrator around the Z-axis while the forks 1 and 2 make automatic vibrations in the X-axis direction at a certain resonance frequency, Coriolis forces corresponding to the angular velocity omega are generated in parallel in both forks in the opposite direction. The alternating torque T caused by the Coriolis force acting on one fork generates a voltage by causing the detecting sections 4 and 5 to make alternate angular vibrations through the section 3. The deflection of the alternate angular vibrations is obtained from the electrode of each section 4 and 5 as electric signals. Since the vibrator has such an integrated structure, the vibrator is suitable for mass production and, since the detecting sections are separated from the tuning forks by the connecting section, no leakage component which appears in a measurement error is generated and the measurement accuracy is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibrator, and more particularly to the structure of a vibrator used in a vibrator gyroscope.

[0002]

2. Description of the Related Art Conventionally, a mechanical rotary gyroscope has been used as an inertial navigation system for airplanes and ships. Although it has stable performance, the size of the device is large, the price is high, and it is difficult to incorporate it in a small device.

Further, in recent years, a vibrating angular velocity sensor for vibrating an object and detecting the Coriolis force from a detecting element on the vibrating object has been put into practical use.

In these, the movement of the mass which constitutes the gyroscope is vibration. Therefore, when the rotational force is applied, the Coriolis force is generated as a force having a frequency equal to the frequency of the mass and perpendicular to the vibration direction.

The principle of the vibration type angular velocity sensor is to measure the angular velocity by detecting the vibration caused by this force.

As an example of the angular velocity sensor based on the above principle, an example of the composite vibrator disclosed in Japanese Patent Laid-Open No. 3-226621 is shown in FIG.

In the perspective view of FIG. 2, 101 and 102 are detection piezoelectric elements, 103 and 104 are coupling members, and 105,
Reference numeral 106 denotes a driving piezoelectric element, 107 denotes an elastic coupling member, 10
Reference numeral 8 indicates a support pin.

Here, a pair of driving piezoelectric elements 105, 10
In order to drive 6, when a common electrode is used as the facing surface and an AC signal is applied to a driving electrode (not shown) provided on the outer surface of the driving piezoelectric elements 105 and 106, it is supported by the support pin 108. The tuning fork vibration starts around the elastic coupling member 107.

The detecting piezoelectric elements 101 and 102 are coupled to the driving piezoelectric elements 105 and 106 via coupling members 103 and 104.

When the detection piezoelectric element 101 of mass m is vibrating at the velocity v, when the rotation of the angular velocity ω is applied, a Coriolis force having a magnitude of 2 mvω perpendicular to the velocity v is generated in the detection piezoelectric element 101. .

Since the angular velocity sensor vibrates in the tuning fork, the other detecting piezoelectric element 102 vibrates at the velocity -v, and the Coriolis force is -2 mvω.

That is, a pair of detection piezoelectric elements 101,
Corresponding Coriolis forces act on each other, and they are deformed in opposite directions, so that a voltage is generated on the surface by the piezoelectric effect.

[0013]

However, in the above-mentioned conventional composite vibrator, the detecting piezoelectric elements 101 and 102 and the driving piezoelectric elements 105 and 106 are connected by the coupling members 103 and 1 respectively.
04, and two driving piezoelectric elements 105,
It is necessary to connect 106 with the elastic connecting member 107. Therefore, high assembly precision is required, and it is difficult to mass-produce it.

Furthermore, the detecting piezoelectric elements 101, 10
Even if the angular velocity is not applied to 2, an acceleration component due to vibration is generated on the detection axis, so that a leakage component signal is generated. The so-called null voltage due to the leak component signal appears as a drift in the measurement error, and there is a problem that the accuracy is significantly deteriorated.

In order to solve these problems, an object of the present invention is to provide a vibrator which detects only the rotational torque due to the Coriolis force of the tuning fork and is suitable for mass production and has high measurement accuracy.

[0016]

In order to achieve the above object, the vibrator of the present invention adopts the following structure.

The vibrator of the present invention is characterized by having a tuning fork and a detecting portion provided integrally with the tuning fork for detecting the rotational torque due to the Coriolis force generated in the tuning fork.

The vibrator of the present invention is a vibrator having a tuning fork and a detector provided integrally with the tuning fork for detecting a rotational torque due to the Coriolis force generated in the tuning fork, and a piezoelectric material is provided in the detector. And

A vibrator according to the present invention is a vibrator having a tuning fork and a detecting portion provided integrally with the tuning fork for detecting a rotational torque due to a Coriolis force generated in the tuning fork, and a piezoelectric material is provided for the tuning fork and the detecting portion. It is characterized by

[0020]

In the vibrator of the present invention, when an angular velocity of ω is applied around the tuning fork axis while the tuning fork is vibrating at the velocity v, the two tuning fork parts are proportional to the product of the velocity v and the input angular velocity ω. Coriolis force Fc is generated, and the tuning fork is alternately vibrated around the tuning fork shaft at the same frequency as the tuning fork.

Along with this, the detection portion formed integrally with the tuning fork also vibrates at the same frequency around the tuning fork shaft, and a detection output proportional to the angular velocity is generated.

The detector does not vibrate when no angular velocity is applied. Therefore, no detection output is generated and no leakage voltage is generated.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings. 1 is a perspective view showing a vibrator according to a first embodiment of the present invention. As shown in FIG. 1, the vibrator is integrally formed from one crystal substrate by a photolithography technique and an etching technique.

The tuning forks 1 and 2 are arranged around the connecting portion 3, and the bases of the tuning forks 1 and 2 are arranged at one end of the connecting portion 3.
Further, the detecting portions 4 and 5 are arranged at the other end of the connecting portion 3, and the end portions of the detecting portions 4 and 5 are connected to a ring-shaped support portion 6. Electrodes (not shown) are provided on the detectors 4 and 5, and a metal film of gold or the like is formed on the electrodes by a vacuum deposition method.

It is assumed that a voltage is applied to the tuning forks 1 and 2 by an electrode (not shown), and the tuning forks 1 and 2 are self-excited at a resonance frequency in the x-axis direction. When an angular velocity ω is applied to this oscillator about the z-axis, Coriolis force Fc corresponding to the angular velocity ω is generated in both tuning forks 1 and 2 in directions opposite to each other.

[0026] Here, the velocity v of the vibration _{v = a · sinω 0 t ‥‥‥} (1) a: the amplitude of the vibration tuning fork ω _0: If the period of the vibration, the Coriolis force Fc acting on one of the tuning fork is It becomes as follows. Fc = 2mωv = 2mωa · sinω ₀ t ··· (2) m: mass of vibrating part of tuning fork

The alternating torque T due to the Coriolis force is T = 2Fc (L / 2) = 2Lmωasinω ₀ t (3) L: distance between tuning forks, and this alternating torque is transmitted through the connecting portion 3. When the detectors 4 and 5 are vibrated at an alternating angle, the detectors 4 and 5 generate a voltage by the piezoelectric effect.

The declination of this alternating angle vibration is obtained as an electric signal from the electrodes (not shown) of the detection units 4 and 5.

Further, if this electric signal is amplified, synchronously detected in the vibration cycle of the tuning fork, and rectified, a voltage proportional to the angular velocity is obtained, and an angular velocity detecting device (gyroscope) can be realized.

Next, another embodiment of the vibrator of the present invention will be described. FIG. 3 shows a vibrator according to the second embodiment of the present invention.

As shown in FIG. 3, the detecting portions 4 and 5 are tapered with respect to a supporting portion (not shown). As shown in FIG. 3, the detectors 4 and 5 have a tapered shape, which has the effect of increasing the amount of deformation of the detectors 4 and 5 and improving the sensitivity.

FIG. 4 shows a vibrator according to the third embodiment of the present invention. The vibrator shown in FIG. 4 is formed by forming two sets of tuning forks having the same phase and the same frequency, thereby increasing the alternating torque shown in the equation (3) and increasing the deformation amount of the detecting portion.

In FIG. 4A, the detectors 4 and 5 are linear, and in FIG. 4B, the detectors 4 and 5 are tapered.
Two sets of tuning forks are provided at both ends of the detectors 4 and 5. In the structure shown in FIG. 4, the deformation amount is further increased.

FIG. 5 shows a vibrator according to the fourth embodiment of the present invention.

As shown in FIG. 5, the connecting portion 3 is provided in the direction opposite to the tuning fork side of the embodiment shown in FIG. 1, and the detecting portions 4 and 5 are provided at the tip of the connecting portion 3. .

In the vibrator shown in FIG. 5, by providing the tuning forks 1 and 2 above the connecting portion 3, the upper part of the connecting portion 3 becomes a complete tuning fork vibrator, so that the length of the entire vibrator increases. However, there is an advantage that the vibration is stable.

In FIG. 5A, the detecting portions 4 and 5 are linear, and in FIG. 5B, the detecting portions 4 and 5 are tapered, so that the deformation amount is further increased.

FIG. 6 shows a vibrator according to the fifth embodiment of the present invention.

The connecting portion 3 is provided in the direction opposite to the tuning fork side of the embodiment shown in FIG. 1, and the detecting portion 4 is provided at the connecting portion 3 on the opposite side of the tuning fork.
5 is provided, and two sets of tuning forks having the same frequency and the same frequency are formed, thereby increasing the alternating torque shown in the above equation (3) and increasing the deformation amount of the detecting portion.

In FIG. 6A, the detecting portions 4 and 5 are linear, and in FIG. 6B, the detecting portions 4 and 5 are tapered, so that the deformation amount is increased.

In the embodiment described above, an example of two detecting parts is shown, but the number of detecting parts is not limited to this, and the detecting parts 4 shown in FIG. Only one detection unit 5 may be provided, or four detection units may be provided by combining the vibrators shown in FIGS. 1 and 5.

Furthermore, in order to increase the sensitivity of the detecting section, a piezoelectric material may be applied or adhered to the detecting section. As this piezoelectric material, piezoelectric ceramics (barium titanate, lead zirco titanate, multi-component solid solution ceramics)
Alternatively, barium titanate single crystal can be applied.

Furthermore, in order to increase the stability of the vibrator,
A piezoelectric material may be applied or adhered to the tuning fork portion.

Further, the example of the material of the oscillator substrate is quartz, but a material having piezoelectricity such as lithium tantalate single crystal, lithium niobate single crystal, or lithium borate single crystal may be used. Alternatively, a piezoelectric material may be applied or adhered to the above to form the vibrator.

[0045]

As is apparent from the above description, the vibrator according to the present invention has an effect that it has an integrated structure as a whole and that mass productivity is good. Furthermore, since the detection unit and the tuning fork are separated from each other via the connection unit, the detection unit does not vibrate in a state where no angular velocity is applied, so that no detection output is generated and no leak signal component is generated. Therefore, the drift due to the leak signal component does not appear in the measurement error, and the measurement accuracy is greatly improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a vibrator according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a vibrator in a conventional example.

FIG. 3 is a perspective view showing a vibrator according to a second embodiment of the present invention.

FIG. 4 is a plan view showing a vibrator according to a third embodiment of the present invention.

FIG. 5 is a plan view showing a vibrator according to a fourth embodiment of the present invention.

FIG. 6 is a plan view showing a vibrator according to a fifth embodiment of the present invention.

[Explanation of symbols]

 1 tuning fork 2 tuning fork 3 connecting part 4 detecting part 5 detecting part 6 supporting part

Claims (3)

[Claims] 1. A vibrator comprising a tuning fork and a detector provided integrally with the tuning fork to detect a rotational torque due to a Coriolis force generated in the tuning fork. 2. A vibrator having a tuning fork and a detector provided integrally with the tuning fork for detecting a rotational torque due to Coriolis force generated in the tuning fork, wherein the detector is provided with a piezoelectric material. 3. A vibrator having a tuning fork and a detecting section provided integrally with the tuning fork for detecting a rotational torque due to Coriolis force generated in the tuning fork, wherein a piezoelectric material is provided in the tuning fork and the detecting section. Oscillator.