JP3310029B2 - Vibrator - Google Patents

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 a vibrator used for a vibrator gyroscope.

[0002]

2. Description of the Related Art Conventionally, mechanical rotary gyroscopes have been used as inertial navigation devices for airplanes and ships. Although it has stable performance, it is bulky, expensive and difficult to incorporate into small equipment.

In recent years, a vibration type angular velocity sensor which vibrates an object and detects Coriolis force from a detection element on the vibrating object has been put into practical use.

[0004] In these, the motion of the mass constituting the gyroscope is oscillating. Therefore, when a rotational force is applied, the Coriolis force is generated as a force perpendicular to the vibration direction at a frequency equal to the frequency of the mass.

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

As an example of an angular velocity sensor based on the above principle, FIG. 2 shows an example of a composite vibrator disclosed in Japanese Patent Laid-Open Publication No. Hei 3-226621.

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

Here, a pair of driving piezoelectric elements 105, 10
When an AC signal is applied between the opposing surface as a common electrode and an unillustrated driving electrode provided on the outer surface of the driving piezoelectric elements 105 and 106 in order to drive the Tuning fork vibration is started around the elastic coupling member 107 to be driven.

The detecting piezoelectric elements 101 and 102 are connected to the driving piezoelectric elements 105 and 106 via connecting members 103 and 104, respectively.

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

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

That is, a pair of detecting piezoelectric elements 101,
Opposite Coriolis forces act on each other and deform in opposite directions, and a voltage is generated on the surface by the piezoelectric effect.

[0013]

However, in the above-described conventional composite vibrator, the detecting piezoelectric elements 101 and 102 and the driving piezoelectric elements 105 and 106 are connected to the coupling members 103 and 1.
04, and two driving piezoelectric elements 105,
It is necessary to couple 106 with an elastic coupling member 107. For this reason, high assembly accuracy is required, and it cannot be said that mass production is difficult.

Further, 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 leak component signal is generated. There is a problem that a so-called null voltage due to the leak component signal appears as a drift in a measurement error, and significantly lowers accuracy.

[0015] In order to solve these problems, an object of the present invention is to provide a vibrator that detects only the rotational torque due to the Coriolis force of a 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 employs the following configuration.

The vibrator of the present invention is provided through a slit.
Tuning fork and rotational torque due to Coriolis force generated in the tuning fork
The vibrator is integrally formed with the detection unit that detects
Te, to connecting the tuning fork and the detecting portion to the slit portion
And a base portion of the tuning fork at one end of the connection portion.
Connected to the other end of the connecting portion and to the tip of the tuning fork.
Connecting the detection unit, wherein the detection unit is tapered,
A support portion is coupled to an end of the tapered detection portion.
And wherein the Tei Rukoto.

[0018]

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 vibrated at the velocity v, the two tuning fork portions are proportional to the product of the velocity v and the input angular velocity ω. The generated Coriolis forces Fc are generated, and the tuning fork is caused to alternately vibrate around the tuning fork axis at the same frequency as the tuning fork.

Accordingly, the detection unit formed integrally with the tuning fork also vibrates at the same frequency around the tuning fork axis, and generates a detection output proportional to the angular velocity.

When no angular velocity is applied, the detecting section does not vibrate. Therefore, no detection output is generated and no leakage voltage is generated.

Further, in the vibrator of the present invention, the detecting section
With a tapered shape, and the end of the tapered detector
Deformation in the detector because the support is connected
The amount is increased, and the detection sensitivity is improved.

[0022]

FIG . 1 is a perspective view showing a vibrator according to a reference example. As shown in FIG. 1, the vibrator is formed integrally from one quartz substrate by photolithography and etching.

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, detecting portions 4 and 5 are arranged at the other end of the connecting portion 3, and the ends of the detecting portions 4 and 5 are connected to a ring-shaped support portion 6. The detection units 4 and 5 are provided with electrodes (not shown), and these electrodes are formed of a metal film such as gold by a vacuum deposition method.

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 the vibrator about the z-axis, a Coriolis force Fc corresponding to the angular velocity ω is generated in both tuning forks 1 and 2 in parallel and in opposite directions.

[0025] 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 looks like this: 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 given by: T = 2Fc (L / 2) = 2Lmωa · sinω ₀ t (3) When the detection units 4 and 5 are caused to vibrate in an alternating angle, the detection units 4 and 5 generate a voltage by a piezoelectric effect.

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

Further, if the electric signal is amplified, synchronously detected at the oscillation period of the tuning fork, and rectified, the voltage becomes proportional to the angular velocity, and an angular velocity detecting device (gyroscope) can be realized.

Next, an embodiment according to the present invention will be described with reference to the drawings . FIG. 3 shows a vibrator according to an embodiment of the present invention .

As shown in FIG. 3, the detectors 4 and 5 are tapered with respect to a support (not shown). By forming the detection units 4 and 5 in a tapered shape as shown in FIG. 3, there is an effect that the amount of deformation of the detection units 4 and 5 is increased and the sensitivity is improved.

FIG. 4 shows a vibrator according to a reference example, not an embodiment of the present invention. In the vibrator shown in FIG. 4, by forming two sets of tuning forks having the same phase and the same frequency, the alternating torque shown by the above-mentioned equation (3) is increased, and the amount of deformation of the detecting section is increased.

FIG. 4A shows the detectors 4 and 5 having a linear shape, and FIG. 4B shows the detectors 4 and 5 having a tapered shape.
Two sets of tuning forks are provided at both ends of the detection units 4 and 5. In the configuration shown in FIG. 4, the amount of deformation is further increased.

FIG. 5 shows a vibrator according to a reference example, not an embodiment of the present invention.

As shown in FIG. 5, the connecting portion 3 is provided in the direction opposite to the direction of the tuning fork 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, since the tuning forks 1 and 2 are provided above the connecting portion 3, the upper portion of the connecting portion 3 becomes a complete tuning fork vibrator, and the overall length of the vibrator increases. However, there is an advantage that the vibration is stabilized.

FIG. 5 (a) shows the detectors 4 and 5 in a linear shape, and FIG. 5 (b) shows the detectors 4 and 5 in a tapered shape to further increase the amount of deformation.

FIG. 6 shows a vibrator according to a reference example, not an 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 on the connecting portion 3 on the side opposite to the tuning fork.
5 and further, two sets of tuning forks having the same phase and the same frequency are formed, thereby increasing the alternating torque shown by the above-mentioned equation (3) and increasing the amount of deformation of the detecting section.

FIG. 6 (a) shows the detectors 4 and 5 in a linear shape, and FIG. 6 (b) shows the detectors 4 and 5 in a tapered shape to further increase the amount of deformation.

In the embodiment described above, an example of two detectors has been described. However, the number of detectors is not limited to this, and the detector 4 shown in FIG. Only one detecting unit 5 may be provided, or the number of detecting units may be four by combining the transducers shown in FIGS.

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

Further, 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 in which the material of the substrate of the vibrator is quartz is described. However, a material having piezoelectricity such as a single crystal of lithium tantalate, a single crystal of lithium niobate, and a single crystal of lithium borate may be used. For example, a vibrator may be formed by applying or bonding a piezoelectric material.

[0044]

As is apparent from the above description, the vibrator according to the present invention has an integral structure and has an effect that mass productivity is good. Further, since the detecting section and the tuning fork are separated via the connecting section, the detecting section 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 leakage signal component does not appear in the measurement error, and the measurement accuracy is greatly improved.

Further, in the vibrator of the present invention, the detecting unit
With a tapered shape, and the end of the tapered detector
Deformation in the detector because the support is connected
This has the effect of increasing the amount and improving the detection sensitivity.
You.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a vibrator according to a reference example, not an 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 the embodiment of the present invention .

FIG. 4 is a plan view showing a vibrator according to a reference example, not an example of the present invention.

FIG. 5 is a plan view showing a vibrator according to a reference example, not an example of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tuning fork 2 Tuning fork 3 Connecting part 4 Detecting part 5 Detecting part 6 Supporting part

Claims (1)

(57) [Claims] 1. A tuning fork provided through a slit, and a detector for detecting a rotational torque caused by a Coriolis force generated in the tuning fork.
And a connecting part that connects the tuning fork and the detection part to the slit part, and connects a base part of the tuning fork to one end of the connecting part. The other end and the tip of the tuning fork are connected to the detection unit , and the detection unit has a tapered shape, and the tapered shape is
A vibrator , wherein a support portion is coupled to an end of the detection portion .