JP2000055665A - Angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angular velocity sensor of a small size and a light weight. SOLUTION: In an angular velocity sensor, a fluid 9 is filled in a passage 41 for converting an angular acceleration to a flow speed of a fluid and a light wave guide oscillator 1 comprising an elastic body deformed and oscillated corresponding to the flow speed and having a light transmissivity is installed on the passage. A light of a light emitting device is wave-guided from a fulcrum side of the light wave guide oscillator and the light is radiated from a tip end of the light wave guide oscillator, i.e., a released end. A motion of the radiation point (or line) of the light is detected by a light-receiving device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for detecting the direction of a moving object such as a passenger car or detecting angular velocity or angular acceleration for detecting a shake of a video camera.

[0002]

2. Description of the Related Art Conventionally, a gyrocompass or the like utilizing the power of Coriolis has been used.

[0003]

The one using a spinning top has a short bearing life, consumes a large amount of power to maintain high-speed rotation of the spinning top, has a complicated mechanism, is difficult to reduce in size and weight, and is expensive. There are problems.

[0004] In the case of using a vibrator, for example, in the case of using a ceramic vibrator, it is difficult to form a fulcrum of the vibrator, and an error in assembling the fulcrum greatly affects the performance. The error greatly affects the performance, which makes it difficult to reduce the size and weight and is expensive.

When the angular velocity to be detected is three-dimensional, three sensors are required, so that it is difficult to reduce the size and weight of an apparatus or a product incorporating the three sensors.

[0006]

SUMMARY OF THE INVENTION The present invention does not utilize Coriolis forces. The present invention utilizes inertial force that acts when angular acceleration is applied to an object. For example, when an angular acceleration is applied to a container containing a fluid, the fluid receives a force that maintains motion due to inertia, that is, the fluid receives an angular acceleration in a direction opposite to the applied angular acceleration with respect to the container, and the fluid rotates. The force works and rotates and flows.

Since the flow velocity of the rotational flow is roughly proportional to the time integral of the angular acceleration, the dimension in the unit system is the angular velocity. However, due to friction, it decays with time. Assuming that the flow velocity is Vt, Vt can be expressed by equation (1). θt
Is the angular velocity, k1 is a constant determined by the flow path shape and the fluid, k2
Is a constant related to friction based on viscosity, C is a constant related to initial conditions, and t is time.

[0008]

(Equation 1)

When the angular velocity θt is given by the equation 2, Vt is
It is expressed by Equation 3. When the angular frequency ω is sufficiently large, it is expressed by Equation (4).

[0010]

(Equation 2)

[0011]

(Equation 3)

[0012]

(Equation 4)

The rotational flow is detected to detect the time integral of angular acceleration, that is, the angular velocity. The means for detecting the rotational flow is as follows. A vibrator is formed of an elastic body having light transmittance, and is installed in a flow path. Light is introduced from a fixed portion side of the vibrator, that is, a fulcrum side, and light is emitted from a tip portion, that is, an open end of the vibrator. The light-emitting device is installed at the position, and the displacement of the open end of the vibrator and the displacement of the light emission point due to the flow of the fluid are detected by the light-receiving device installed opposite to the open end.

The above-mentioned vibrator will be called an optical waveguide vibrator. As the material constituting the optical waveguide resonator, a material having high light transmittance, a refractive index to light higher than that of a fluid, and a lower elastic modulus is suitable. Also, in the cross section perpendicular to the light traveling direction, the refractive index is distributed higher toward the center,
Materials that are uniformly distributed can be used, and silicate glass, plastic, and the like can be used.

When the refractive index of the optical waveguide resonator is lower than or close to that of the fluid, the optical waveguide resonator is coated with a substance having a lower refractive index than that of the optical waveguide resonator, and total reflection of light is performed. A surface is preferably formed. Further, a reflective surface may be formed by plating a metal or an alloy such as gold, silver, and aluminum by a method such as vapor deposition.

The shape of the optical waveguide resonator is plate-like or film-like, rod-like or fiber-like.

When the angular acceleration to be detected is one-dimensional, the optical waveguide vibrator can be formed in a plate shape or a film shape to increase the detection sensitivity.

The fluid needs to have a melting point lower than the ambient temperature of use and a light transmitting property, and it is desirable that the fluid has a large specific gravity, a refractive index lower than that of the optical waveguide resonator, and a low viscosity. A liquid such as water, ethyl alcohol, methyl alcohol, glycerin, diethyl ether, paraffin oil, silicone oil, or a mixture of several kinds thereof can be used.

As the light emitting device, a light emitting diode element, a semiconductor laser element or the like can be used.

The light receiving device is a one-dimensional or two-dimensional optical sensor, and can use a photodiode element, a photodiode array element, a phototransistor element, a phototransistor array element, a CCD (charge coupled element) optical sensor, or the like.

When the angular acceleration to be detected is one-dimensional, the flow path of the fluid is annular. For example, a pipe can be bent into a donut shape to form a flow path.

If the angular acceleration to be detected is two-dimensional or more, the flow path of the fluid has a hollow spherical shape. That is, a spherical structure (hereinafter referred to as “structure B”) is arranged in a structure (hereinafter referred to as “structure A”) having a spherical space therein, and the hollow sphere is formed by the structures “A” and “B”. And a space is defined as a flow path.

At least a part of the structure constituting the flow path is made of an elastic material, and absorbs a change in pressure of the fluid based on a difference in thermal expansion coefficient. As the elastic body, a rubber-like substance such as synthetic rubber, polyurethane resin, or silicone resin, or a plate or foil having a small spring constant such as metal or plastic can be used.

The structure B has a space formed therein, and a gas such as air is sealed in the space with a lid made of an elastic material.
Alternatively, the pressure of the fluid can be increased by forming a space inside the structure A, sealing the gas in the space with a lid made of an elastic body, and contacting the lid with the fluid filled in the hollow spherical space. Changes can be absorbed, and the degree of freedom in selecting the fluid to be used can be increased.

If the angular acceleration to be detected is three-dimensional, two sets of light emitting devices, optical waveguide vibrators and light receiving devices are installed in one hollow spherical channel. However, the light emitting device may be common and may be one.

[0026]

Embodiment 1 FIGS. 1, 2 and 3 show an embodiment in which the angular acceleration to be detected is one-dimensional. FIG. 2 is an enlarged sectional view of the detector (5) in FIG. 1, and FIG. 3 is a top view when the element holder lid (52) is removed and FIG. 2 is used as a reference.

As shown in FIG. 3, a film-shaped optical waveguide vibrator (1) is inserted into a slit (53) formed in an element holder (51), and a position opposing an end face of the optical waveguide vibrator. Together with the light-emitting diode element incorporated in the device is fixed by a transparent adhesive (8).

In the optical waveguide vibrator (1), aluminum is vapor-deposited on the front and back surfaces of the polyethylene terephthalate film, cut into a predetermined shape, and the aluminum facing the light emitting diode element (21) is brought into contact with the slit (53). It is the thing removed by the etching method to the extent of about one half of the part.

When an angular acceleration θt is applied in the direction of the arrow shown in FIG. 1, the open end of the optical waveguide vibrator (1) moves in the direction of the arrow shown in FIG.

A photodiode array element (3) is assembled at a position facing the open end of the optical waveguide resonator (1), and is fixed with an adhesive (8).

An element holder lid (52) was bonded and fixed to the element holder (51) to form a flow path (4), thereby forming a detector (5).

As shown in FIG. 1, a pipe made of fluororubber was formed into a bent annular flow path (41), and was bonded and fixed to a detector (5).

From the fluid sealing hole (54) of the element holder lid (52), white kerosene was sealed and sealed to form an angular velocity sensor.

[0034]

Embodiment 2 FIG. 3 shows an embodiment in which the angular acceleration to be detected is three-dimensional. Structure A (61) and Structure B
By (62), a hollow spherical flow path (42) is formed. The structure B (62) includes the support 1 (631) and the support 2 (63).
2) It is fixed to the structure A (61) by the support 3 (633).

A fiber made of silicate glass and two optical waveguide fibers coated with silicate glass having a lower refractive index than the glass are passed through the inside of the structure B (62) from the support portion 3 (633). The optical waveguide vibrator 1 (11) and the optical waveguide vibrator 2 (12) were formed by projecting into the hollow spherical flow path (42). A cylindrical hole (621) is formed to increase the length between the open end and the fulcrum of the optical waveguide resonator, reduce the spring constant, and increase the sensitivity.

The open ends of the optical waveguide vibrator 1 (11) and the optical waveguide vibrator 2 (12) are respectively connected to the CCD optical sensor 1 (71) through engineering windows (611) made of a material having optical transparency. And the CCD optical sensor 2 (72). CCD light sensor 1 (71) and CCD
The optical sensor 2 (72) is a two-dimensional optical sensor.

The light emitting diode element (22) was bonded and fixed to the support portion 3 (633) at a position facing the end face of the optical waveguide fiber with a transparent adhesive (83).

A cavity (622) was formed in the structure B (62), and air was sealed in the cavity (622) with a lid (623) made of fluoro rubber and an adhesive.

The hollow spherical channel (42) was sealed with ethylene glycol.

[0040]

The angular velocity sensor according to the present invention detects the time integral of the angular acceleration and has a characteristic that the integral attenuates with time. Therefore, the angular velocity sensor is most suitable for detecting a camera shake of a video camera, for example. is there.

Semiconductors can be used for the light emitting device and the light receiving device, and their miniaturization and weight reduction are extremely easy.
Therefore, a small and lightweight angular velocity sensor can be obtained.
In particular, when the angular acceleration to be detected is three-dimensional, three sensors are conventionally required, but in the present invention, only one sensor is required, which greatly contributes to reduction in size and weight.

There is no mechanical contact part such as a bearing, and the life is long.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of the detector (5) of FIG.

FIG. 3 is a top view of FIG. 2 showing an element holder lid (52).
FIG.

FIG. 4 is a sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 optical waveguide oscillator 11 optical waveguide oscillator 1 12 optical waveguide oscillator 2 111 fulcrum of optical waveguide oscillator 1 112 optical waveguide fiber 21, 22 light emitting diode element 211 light emitting diode chip 212, 222 light emitting diode element lead 3 photodiode array Element 31 Photodiode array chip 32 Photodiode element lead 4 Flow path 41 Annular flow path 42 Hollow spherical flow path 5 Detector 51 Element holder 52 Element holder lid 53 Slit 54 Liquid sealing hole 61 Structure A 611 Engineering window 62 Structure Body B 621 Tube upper hole 622 Cavity 623 Lid 631 Support 1 632 Support 2 633 Support 3 71 CCD optical sensor 1 713 CCD optical sensor lead 72 CCD optical sensor 2 8, 81, 83 Adhesive 9 Fluid

Claims (7)

[Claims] An annular flow path filled with a fluid is made of a light-transmitting elastic body, one end of which is mechanically supported (hereinafter, referred to as a support end), and the other end of which is open (hereinafter, open). An angular velocity sensor in which an optical waveguide vibrator is installed, a light emitting device is installed facing a support end of the optical waveguide oscillator, and a light receiving device is installed facing an open end. 2. The angular velocity sensor according to claim 1, wherein at least a part of the annular flow path is formed of an elastic body. 3. The optical waveguide resonator according to claim 1, wherein said optical waveguide resonator is in the form of a film.
Angular velocity sensor 4. A spherical structure (hereinafter referred to as a structure B) in a structure having a spherical space therein (hereinafter referred to as a structure A).
It is written. ), A hollow spherical space is formed by the structure A and the structure B, and the hollow spherical space is filled with a fluid, and a fiber made of an elastic material having a light transmitting property is attached to the support portion of the structure B. And one end of the fiber penetrates the structure B
The optical waveguide vibrator is constructed by projecting and opening into a hollow spherical space so as to face the inner wall surface of A. An angular velocity sensor in which a light receiving device is installed at the site and a light emitting device is installed at the other end of the fiber. 5. The angular velocity sensor according to claim 4, wherein at least a part of the structure A or at least a part of the structure B in claim 4 is formed of an elastic body. 6. The angular velocity sensor according to claim 4, wherein the structure B according to claim 4 is configured such that a space is formed therein and gas is sealed in the space with a lid made of an elastic material. 7. The structure A according to claim 4, wherein a space is formed therein, and gas is sealed in the space with a lid made of an elastic material, and the lid comes into contact with the fluid filled in the hollow spherical space. The angular velocity sensor according to claim 4, wherein: