JPH0324989B2 - - Google Patents

Description

Detailed Description of the Invention [Background and Objectives of the Invention] The present invention relates to an optical fiber two-dimensional acceleration sensor, and particularly to an optical fiber two-dimensional acceleration sensor suitable for detecting acceleration in two directions with one sensor. It is related to.

Conventionally, electric sensors such as piezoelectric elements and semiconductor elements have been mainly used as acceleration sensors. However, these sensors almost always detect acceleration in a single direction, are susceptible to electromagnetic induction, require noise prevention measures, and are limited by the sensor's usage conditions due to the environmental resistance characteristics of the element. There was a drawback that there was.

In response, various acceleration sensors using optical fibers have been proposed, but most of them detect acceleration in a single direction, and there are currently very few that can detect acceleration in two dimensions. be.

The present invention has been made in view of the above, and its purpose is to be able to detect acceleration in two directions with one sensor, to have a simple structure, and to have excellent stability and reliability. An object of the present invention is to provide an optical fiber two-dimensional acceleration sensor.

[Summary of the Invention] The present invention is characterized by a light transmitting optical fiber, a light receiving optical fiber having three or more fibers, a ferrule to which one end surface of each of the optical fibers is fixed,
A microlens is provided close to this ferrule, and the ferrule of this microlens is provided with a reflecting plate having one end of an elastic support rod fixed to the back surface provided facing the opposite side, and a reflection plate having one end of an elastic support rod fixed to the back surface of the microlens. a housing for housing and fixing the microlens and the ferrule, the other end of which is fixed; a light emitting element connected to the other end of the light transmitting optical fiber;
A light-receiving element connected to the other end of each of the light-receiving optical fibers and a signal obtained by amplifying the output proportional to the amount of light received by each light-receiving element are input, and the acceleration in the two-dimensional direction orthogonal to the elastic support rod is calculated. The light-receiving optical fibers each include a signal processing circuit that sends out corresponding outputs, and each of the light-receiving optical fibers receives the reflected light that enters the light-receiving optical fiber when the acceleration acting on the microlens side end face is zero. They are arranged at a certain point on the same circumference so that the amount of light reflected from the plates is equal.

[Examples] The present invention will be described in detail below using examples shown in FIGS. 1 to 6.

FIG. 1 is an explanatory diagram of the overall configuration of an embodiment of the optical fiber two-dimensional acceleration sensor of the present invention. 1st
In the figure, 1 is an optical fiber for transmitting light, 2 ₁ to 2n
are optical fibers for receiving light, 3 is a ferrule to which one end of each of the optical fibers 1, _{2 1} to 2n is fixed, 4 is a microlens made of a ball lens or a rod lens provided close to the ferrule 3, and 5 is a microlens. A reflector plate 4 has one end of an elastic support rod 6 fixed to the back surface facing the opposite side from the ferrule 3, and a microlens 4 and ferrule 3 have the other end of the elastic support rod 6 fixed. This is a housing that stores and fixes the

When light from a light emitting element 8 such as an LED or a semiconductor laser propagates through the optical fiber 1 for phototravel and enters the microlens 4, this light becomes almost parallel light by the microlens 4, and is reflected by the reflection plate 5. The light enters the microlens 4 again, and the light gathers to form a real image near the ends of the light-receiving optical fibers 2 ₁ to 2n, and then enters and propagates to the light-receiving optical fibers 2 ₁ to 2n. Optical fiber 2 ₁ ~ 2n
The light is received by the light receiving elements 9 ₁ to 9n connected to the other end, respectively. The electrical outputs converted from light to electricity by the light receiving elements 9 ₁ to 9n are sent to the light receiving circuit 10 _{1 .}
The outputs V ₁ to Vn of the light receiving circuits 10 ₁ to 10n, each proportional to the received light level, are input to the signal processing circuit 11 and processed. Outputs Vx and Vy proportional to are sent out.

The elastic support rod 6 has one end fixed to the reflection plate 5 and the other end fixed to the housing 7, so when acceleration is applied to the housing 7, as shown in FIG.
The elastic support rod 6 is deflected from the position shown by the solid line to the position shown by the dotted line, and the angle of the reflection plate 5 changes by θ in proportion to the acceleration. The proportionality constant in this case is determined by the mass of the reflecting plate 5 and the elastic modulus of the elastic support rod 6. At this time, the angle of the reflected light changes by 2θ, and as a result,
The imaging position changes.

Figure 3 shows the light receiving optical fibers 2 ₁ to 2n in Figure 1.
FIG. 3 is an explanatory diagram showing an example of the arrangement of fixed end faces on the ferrule 3, and illustrates a case where there are four light-receiving optical fibers. In FIG. 3, the four-core light-receiving optical fibers 2 ₁ to _{2 4} are arranged in a square arrangement, and when the acceleration is zero and the angle θ of the reflector 5 is 0, the light from the transmitting optical fiber 1 is reflected. The light receiving optical fibers ₂₁ to ₂₄ are connected so that the real image of the light is connected to the approximate center of the optical fibers 21 to ₂₄ as shown in the solid hatched area I, and the received light outputs _V1 = _V2 = _V3 = _V4 . The position of 2 ₄ and the inclination of the microlens 4 and the reflector 5 are adjusted.

Here, for example, when acceleration is applied in the y direction, the image I moves to the position shown by the broken line, and as a result, the received light outputs V ₁ to _{V 4} change. In this example, V ₂ = V ₄
Since the relationship remains unchanged, Vx=0, and V ₁
A y-direction acceleration output Vy corresponding to −V ₃ is obtained.
If the acceleration is in an arbitrary direction, the x-direction acceleration output Vx and the y-direction acceleration output Vy correspond to V ₂ −V ₄ and V ₁ −V ₃
is obtained. Incidentally, the size of the image I can be changed depending on the wire diameter (the diameter of the core and the cladding) and the number of fibers of the light-traveling optical fiber 1.

In addition, FIG. 4 is an explanatory diagram corresponding to FIG. 3 showing another example of the arrangement of the light receiving optical fibers. In FIG. 4, there are three light receiving optical fibers, and the light receiving optical fibers 2 ₁ - 2 ₃ is an equilateral triangular array. In this case, Vx and Vy can be obtained by processing the received light outputs V ₁ to _{V 3} .

FIG. 5 is a perspective view showing one embodiment of a method for fixing the housing 7 of FIG. 1 to an object to be detected, and FIG. 6 is a perspective view showing another embodiment of the method. In FIG. 5, the housing 7 is attached parallel to the surface of the sensor fixing flange 13 of the object to be detected, and in this case, the acceleration in one direction x parallel to the fixed surface and the acceleration in the direction y perpendicular to the fixed surface can be detected. In addition, in FIG. 6, the housing 7 is attached perpendicularly to the surface of the sensor fixing flange 13, and in this case, acceleration in any direction parallel to the fixing surface (for example, x and y directions perpendicular to each other) can be detected. .

According to the embodiment of the present invention described above, (1) One sensor can detect acceleration in two directions at the same point.

(2) Simple structure and excellent environmental resistance.

(3) There is no influence of induced noise, and it has excellent stability and reliability.

(4) Easy to install on the object to be detected.

(5) Since the acceleration signal is obtained from the relative value of the light reception level of each of the light reception optical fibers 2 ₁ to 2n, the influence of fluctuations in the light emission level of the emission element 8 can be reduced.

[Effects of the Invention] As explained above, according to the present invention, acceleration in two directions can be detected with one sensor,
In addition, the structure is simple, and the structure is excellent in stability and reliability.

[Brief explanation of the drawing]

Fig. 1 is an explanatory view of the overall configuration of an embodiment of the optical fiber two-dimensional acceleration sensor of the present invention, and Fig. 2 is a detailed view of the sensor section to explain the operating principle of Fig. 1 (ferrules are omitted). ), FIG. 3 is an explanatory diagram showing an example of the arrangement of the fixed end face of the light-receiving optical fiber in FIG. 1 to the ferrule, and FIG. An explanatory diagram showing another example of the arrangement of the fixed end surface, FIG.
FIG. 6 is a perspective view showing an embodiment of a method of fixing the housing of FIG. 1 to an object to be detected. DESCRIPTION OF SYMBOLS 1... Optical fiber for light transmission, 2 ₁ - 2n... Optical fiber for light reception, 3... Ferrule, 4... Micro lens, 5... Reflection plate, 6... Elastic supporter, 7... Housing, 8... Light emitting element, 9 ₁ - 9n...light receiving element, 10 ₁
~10n...Light receiving circuit, 11...Signal processing circuit, 12
...Drive times.

Claims (1)

[Claims] 1. A light transmitting optical fiber, a light receiving optical fiber having three or more fibers, a ferrule to which one end of each of the optical fibers is fixed, a microlens provided close to the ferrule, and a microlens provided close to the ferrule. a reflection plate having one end of an elastic support rod fixed to the back surface of the lens opposite to the ferrule; the microlens and the ferrule having the other end of the elastic support rod fixed; A housing for storing and fixing, a light emitting element connected to the other end of the light transmitting optical fiber, a light receiving element connected to the other end of each of the light receiving optical fibers, and an output proportional to the amount of light received by each light receiving element. and a signal processing circuit that inputs each amplified signal and sends out an output corresponding to the acceleration in a two-dimensional direction perpendicular to the elastic support rod, and each of the light receiving optical fibers has a side end surface of the microlens. The light is arranged on the same circumference so that when the acceleration acting on the housing is zero, the amount of light reflected from the reflecting plate that enters each of the light-receiving optical fibers is equal. Fiber two-dimensional acceleration sensor.