JPH0228403Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a device that measures the amount of displacement by converting the amount of mechanical displacement into a change in the amount of light using an optical fiber.

Recently, optical fibers have been increasingly used in place of electric cables. Since optical fibers are not affected by electromagnetic influences like electric cables, they are becoming widely used, especially in the field of communications. However, it is currently only used in a limited number of fields, and it is hoped that it will be used in an even wider range of fields in the future.

This idea was made in view of the above points,
Displacement measurement uses transmission loss due to optical fiber structural scattering (occurred due to interfacial fluctuations between the core and cladding) to measure mechanical displacement, making it possible to measure displacement with a simple structure and high accuracy. The purpose is to provide equipment.

An embodiment of this invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a change measuring device according to this invention. This change measuring device is roughly divided into a measuring section 10, a detecting section 20, and two wires connecting these measuring section 10 and detecting section 20. It is composed of optical fibers 31 and 32.

The measurement unit 10 includes a DC power supply 11, a clock generator 12, and a pulse generator 13 that generates pulses in synchronization with the clock from the clock generator 12.
a, 13b, light emitters 14a, 14b that intermittently operate to emit light in response to pulse outputs from the pulse generators 13a, 13b, and a light receiving window 15 attached to one end of the optical fiber 31 to receive light from the light emitter 14a. , a dimmer 16 for adjusting the level of light from the light projector 14b, a light projection window 17 attached to one end of the optical fiber 32 to output light from the optical fiber 32, and a light projection window 17 disposed opposite to the light projection window 17. A light receiver 18 having a photoelectric conversion function, this light receiver 1
8 and the light projection window 17, the dimmer 1
A semi-transparent mirror HM is arranged at an angle such that the light from the projector 14b obtained through 6 can be supplied to the light receiver 18, and the detection unit 20 receives an electrical signal corresponding to the light from the light receiver 18 and measures It consists of a measuring circuit 19 that outputs a quantity.

The detection unit 20 also includes a fluid passage 21 in which a measured quantity (in this embodiment, fluid flow rate) is detected.
and a detection optical fiber 22 disposed so as to traverse the inside of this fluid passage 21. The detection optical fiber 22 is supported in the fluid passage 21 by support parts 23 ₁ , 23 ₂ , and both ends of the detection optical fiber 22 are connected to the optical fibers 31 , 32 by connectors 24 ₁ , 24 ₂ .
It is connected to the.

Next, the operation of this device constructed as described above will be explained with reference to FIG. Intermittent light as shown in FIG. 2a is emitted from the hole thrower 14a. On the other hand, the light projector 14b emits intermittent light as shown in FIG. 2c. As is clear from FIGS. 2a and 2c, the light emitters 14a and 14b are controlled to alternately emit light. This control timing is performed by a clock generator 12.

Thus, the light from the light projector 14a enters the light receiving window 15, passes through the optical fiber 31, the detection optical fiber 22, and the optical fiber 32, and exits the light projecting window 17 as a somewhat attenuated light as shown in FIG. 2b. It grows old and comes out. The light emitted from the light projection window 17 passes through the semi-transparent mirror HM and enters the light receiver 18. Further, the light from the light projector 14b is adjusted by the dimmer 16 to the same level of light as the light coming out from the light projection window 17 (Fig. 2b), as shown in Fig. 2d, and then the semi-transparent mirror HM is irradiated. Therefore, the light incident on the light receiver 18 becomes continuous light having the same level as shown in FIG. 2e, in which the light in FIG. 2b and the light in FIG. 2d are combined. and,
This continuous light is converted into an electrical signal corresponding to the light level and input to the measuring circuit 19. Measuring circuit 19
Now, when a signal in such a state is input, the measured quantity is determined to be "0", and a signal corresponding to the measured quantity "0" is output.

As described above, before flowing fluid into the fluid passage 21 of the detection unit 20, the level of light emitted from the light projection window 17 and the level of light from the light projector 14b obtained via the dimmer 16 are adjusted in advance. The light of the same level obtained by combining these lights is made to enter the light receiver 18, and the signal from the light receiver 18 at that time is set as a reference level in the measurement circuit.

If this condition is set, the fluid passage 2
A change depending on the magnitude of the flow velocity of the fluid flowing through the measuring circuit 19 can be obtained from the measuring circuit 19. That is, due to the flow of the fluid, the detection optical fiber 22 undergoes structural scattering in accordance with the speed of the flow, and the light emitting window 1
7 makes a difference to the light level from the projector 14b obtained via the dimmer 16. Therefore, in the waveform of the input light to the light receiver 18, a difference occurs between the light level from the light projection window 17 and the light level from the dimmer 16, and an output corresponding to the difference is output from the measurement circuit 19. It is something that can be taken out. Therefore, it is possible to take out an output from the measurement circuit 19 that corresponds to the magnitude of the flow velocity of the fluid flowing within the fluid passage 21.

Furthermore, since the noise component generated in the measurement unit 10 is included in the light output from the dimmer 16 and the light output from the light projection window 17 to approximately the same extent, the levels of the two lights are adjusted to be equal. By setting the value as the reference level (0 level), the receiver 1 can be
It is possible to regard the change appearing in the input light of No. 8 as a good measurement value with little noise component. Therefore, measurement accuracy (S/N ratio) can be improved.

Note that the measuring section 10 according to this invention can be similarly implemented even if it is configured not like the embodiment shown in FIG. 1 but as shown in FIG. 3. In FIG. 3, the same parts as in FIG. 1 are given the same reference numerals. In the case of _this FIG.
It is controlled by second electronic shutters 40a and 40b to produce light as shown in FIGS. 2a and 2c.
Even with such a configuration, the same purpose as the above embodiment can be achieved. Further, in the above embodiment, the case where the flow velocity and flow rate of a fluid is measured has been described as an example, but the present invention is not limited to this and can be applied to measurement in a wide range of fields. Furthermore, in the above embodiment, the optical fiber used for detection is separately provided as a detection optical fiber and connected to the transmission optical fiber using a connector, but instead of this configuration, a single optical fiber is used. A portion of the fiber may be used as a detection optical fiber. Note that the detection optical fiber 22 may be a fiber with larger structural scattering than the optical fibers 31 and 32. In addition, this invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without departing from the gist.

As explained above, according to this invention, the amount of mechanical change is measured using the transmission loss caused by the structural scattering of the optical fiber, so the displacement can be measured with a simple structure and with high accuracy. We can provide quantity measuring devices. In addition, since the output light of the optical transmission line and the intermittent light from the intermittent light generating means are combined,
Stable and highly accurate displacement measurement becomes possible without being affected by attenuation of the optical transmission line.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of this invention, Figs. 2 a to e are diagrams showing the operation of the same embodiment, and Fig. 3 is a block diagram of main parts showing a modification of the above embodiment. be. 10... Measuring section, 19... Measuring circuit, 20...
Detection unit, 31, 32...optical fiber.

Claims (1)

[Scope of utility model registration request] An intermittent light generating means that alternately generates intermittent light at predetermined intervals, one intermittent light emitted from the intermittent light generating means is inputted from one end side, and this input light is provided at a predetermined position from the other end side. an optical transmission line using an optical fiber arranged so as to output to a light receiver, the middle part of which is arranged in a measured quantity detection section; and a link between the other end of the optical transmission line and the light receiver. A means for combining the output light of the optical transmission line with the other intermittent light generated from the intermittent light generating means, and a means for combining the output light of the optical transmission line with the other intermittent light generated from the intermittent light generating means, and a means for combining the output light of the optical transmission line with the other intermittent light generated from the intermittent light generating means, and a means for combining the output light of the optical transmission line with the other intermittent light generated from the intermittent light generating means, and a A displacement amount measuring device comprising means for adjusting the other intermittent light in advance so that the other intermittent light becomes light, and a measuring circuit that receives the output from the light receiver and outputs the displacement as a measured amount. .