JPH04265814A - Displacement measuring apparatus - Google Patents

Abstract

PURPOSE:To measure the displacement while securing resistances to noise and surge. CONSTITUTION:A lens 14 with chromatic aberration whereby the position where a focal point is met is changed depending on the wavelength of light is used. A light source 18 emits light by the amount not smaller than a predetermined level in the measuring range. The light from the light source 18 is brought into the lens 14, so that a focal point is met at the position corresponding to each wavelength. A reflecting mirror 15 which shifts in accordance with the displacement of an object to be measured is shifted on a line connecting the focal points. A reflecting returning light of a specific wavelength which meets a focal point on the reflecting surface of the reflecting mirror 15 is detected by a spectrum distribution measuring part 21. The displacement of the object is measured by a displacement measuring part 22 from the position on the spectrum distribution of the reflecting returning light.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement measuring device for measuring the displacement of an object to be measured.

0002

[Prior Art] Conventionally, for example, when detecting an accident point that has occurred in a gas-insulated switchgear, the gas pressure in the section including the accident point increases, so this is detected by a pressure/displacement converter. I was going.

FIGS. 4A and 4B and FIG. 5 show examples of conventional pressure/displacement conversion type displacement measuring devices.

In these figures, reference numeral 1 denotes a pressure/displacement converter to which gas pressure is transmitted, and a disc-shaped diaphragm 3 is airtightly attached to the opening of a pressure vessel 2 that hardly deforms. It has a structure in which strain gauges 4a and 4b are attached to the surface at different positions in the radial direction.

5 denotes these strain gauges 4a, 4b and a resistor R.
1 and R2, 6 is a DC power supply connected between the input terminals of the bridge circuit 5, and 7 is connected between the output terminals of the bridge circuit 5 to amplify its output. It is a high input impedance amplifier.

In such a device, the diaphragm 3 converts changes in gas pressure into changes in mechanical position. The displacement of the diaphragm 3 is detected as a change in the resistance value of the strain gauges 4a, 4b. The output signal of the bridge circuit 5 based on the resistance value change of these strain gauges 4a, 4b is amplified, and the displacement of the diaphragm 3, that is, the pressure change is measured from the output signal.

[0007]

[Problem to be Solved by the Invention] However, when locating the fault point of high-voltage electrical equipment using such a conventional device, there was a problem that the amplifier 7 etc. were easily damaged by lightning surges, accident surges, etc. .

[0008] Furthermore, there is a problem that malfunctions may occur due to electromagnetic waves or surge noise.

An object of the present invention is to provide a displacement measuring device having noise resistance and surge resistance.

0010

[Means for Solving the Problems] To explain the configuration of the present invention to achieve the above object, the displacement measuring device according to the present invention includes a light source that emits light having an amount of light emitted at a predetermined level or more in a measurement range. , a lens with chromatic aberration that focuses the light from the light source at a position corresponding to each wavelength; and a lens with chromatic aberration that focuses the light from the light source at a position corresponding to each wavelength; a reflector that reflects light with a wavelength of The present invention is characterized in that it is configured to include a displacement measurement section that measures displacement of an object.

[0011]

[Operation] Lenses with chromatic aberration have the characteristic that their refractive index changes depending on the wavelength of light. When light from a light source passes through such a lens with chromatic aberration and hits a reflecting mirror that moves as the object to be measured moves, only the light whose wavelength matches the focal point of the reflecting mirror returns as reflected return light. Become. When a change in the spectral distribution of this reflected return light is detected, the displacement of the object to be measured can be measured from the change in the spectral distribution.

Since this device performs optical detection, it will not malfunction due to lightning surges or accidental surges.

[0013]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the first displacement measuring device according to the present invention.
This shows an example.

In the figure, 8 indicates light having an amount of light emitted at a predetermined level or higher in the measurement range, preferably as shown in FIG. 2(a).
A light source that emits light with a substantially flat spectrum distribution as shown in FIG. 9, a condenser consisting of a lens that condenses the light from the light source 8, and an optical fiber 10 that transmits the light condensed by the condenser 9. , 11 is a splitter placed at the tip of the optical fiber 10. For example, the light source 8 has a wavelength of 700n.
A material having a substantially flat spectrum distribution in the range of m to 900 nm is used. Specific examples of the light source 8 include a light emitting diode, a xenon lamp, and a white lamp.

12 is an optical fiber that transmits the light that has passed through the splitter 11; 13 is a micro convex lens that passes the light that exits from the optical fiber 12; 14 is a chromatic aberration lens that is a convex lens that passes the light that has passed through the micro convex lens 13; This is a reflecting mirror that is supported by the object to be measured so as to be displaced as the object is displaced, and projects light that has passed through the chromatic aberration lens 14. As the lens 14 with chromatic aberration, a lens whose chromatic aberration is not corrected is used.

Reference numeral 16 denotes an optical fiber for extracting the reflected return light from the reflecting mirror 15 via the splitter 11, and 17 denotes the optical fiber 1.
18 is a fiber collimating lens that converts the reflected return light outputted from 6 into a parallel beam; 18 is a fiber collimating lens 1;
7 is a diffraction grating that diffracts the reflected return light of the parallel light beam outputted from 7 according to the wavelength; 19 is a condenser lens that condenses the reflected return light arranged in the order of wavelength after passing through the diffraction grating 18; 20 is a condenser lens 19 This is an array sensor that converts the reflected return light that is collected at different positions depending on the wavelength through the 2-wavelength sensor into an electrical signal that corresponds to the wavelength. As the array sensor 20, for example, a photodiode array, a light receiving sensor array such as a CCD, etc. is used.

A spectral distribution measuring section 2 detects changes in the spectral distribution of the reflected return light from the reflecting mirror 15 using the optical fiber 16, fiber collimating lens 17, diffraction grating 18, condensing lens 19, and array sensor 20.
1.

Reference numeral 22 denotes a displacement measuring unit comprising a central processing unit (CPU) that measures the displacement of the object to be measured based on the spectrum distribution measurement result from the spectrum distribution measuring unit 21.

In such a displacement measuring device, light having a substantially flat spectrum distribution as shown in FIG. , when light is projected onto the chromatic aberration lens 14 through the micro convex lens 13, the focal length of the chromatic aberration lens 14 varies from several μm to several μm depending on each wavelength in the light.
It changes by several mm.

On the other hand, the position of the reflecting mirror 15 is displaced in accordance with the displacement of the object to be measured. Only light of a specific wavelength whose focal point is present at the displaced position of the reflecting mirror 15 is reflected as reflected return light, returns to the optical fiber 12 through the opposite route, and is branched to the optical fiber 16 side by the splitter 11.

At this time, the light that is not focused on the reflecting mirror 15 is diffused and does not return to the optical fiber 12.

The reflected return light branched to the optical fiber 16 side by the splitter 11 is converted into a parallel beam by the fiber collimating lens 19, diffracted by the diffraction grating 18 in a direction corresponding to its wavelength, and then reflected by the condenser lens 19. The light is focused on a specific position on the array sensor 20. The array sensor 20 outputs an electric signal according to the wavelength of the reflected return light focused on its surface, as shown in FIG. 2(b).

This electric signal is diffracted by the displacement measuring section 22, and the displacement of the object to be measured corresponding to the position of the reflecting mirror 15 is calculated.

FIG. 3 shows the second displacement measuring device according to the present invention.
This shows an example. This embodiment shows an example in which a green lens is used as the chromatic aberration lens 14 instead of a convex lens. The Grid lens is a cylindrical lens having a characteristic that the refractive index distribution changes in the radial direction, and even when such a lens is used, the same displacement detection operation as in the first embodiment can be performed.

[0026]

Effects of the Invention As explained above, the displacement measuring device according to the present invention takes advantage of the fact that the focal point of the lens with chromatic aberration changes depending on the wavelength of light, and uses the characteristic that the focal position of the lens with chromatic aberration changes depending on the wavelength of light to detect the emission of light above a predetermined level in the measurement range. The light from a light source that emits light having a certain amount of light is passed through the chromatic aberration lens so that it is focused at a position corresponding to each wavelength, and a reflecting mirror that is displaced according to the displacement of the object to be measured aligns these focal points. The object to be measured is displaced on a line, and the reflected return light of a specific wavelength focused on the reflecting surface of the reflecting mirror is detected, and the displacement of the object to be measured is detected from the position on the spectrum distribution of this reflected return light. Therefore, the displacement of the object to be measured can be detected optically.

By converting mechanical displacement into the wavelength of light and detecting it in this way, it is possible to prevent electronic circuits from being damaged or malfunctioning due to lightning surges, accidental surges, and the like.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a first embodiment of a displacement measuring device according to the present invention.

FIG. 2(a) is a wavelength distribution of a light source, and FIG. 2(b) is an output waveform diagram of a wavelength focused at a position where a reflecting mirror is present.

FIG. 3 is a schematic configuration diagram of a second embodiment of the displacement measuring device according to the present invention.

FIGS. 4(a) and 4(b) are a plan view and a sectional view of a conventional pressure/displacement conversion type displacement measuring device.

FIG. 5 is an electrical circuit diagram of the conventional displacement measuring device shown in FIG. 4;

[Explanation of symbols]

8 Light source 9 Condenser lens 10 Optical fiber 11 Brancher 12 Optical fiber 13 Micro convex lens 14 Chromatic aberration lens 15 Reflector 16 Optical fiber 17 Fiber collimating lens 18 Diffraction grating 19 Condenser lens 20 Array sensor 21 Spectrum distribution measuring section 22 Displacement measurement Department

Claims (1)

[Claims] 1. A light source that emits light having an amount of light emitted at a predetermined level or higher in a measurement range, a lens with chromatic aberration that focuses the light from the light source at a position corresponding to each wavelength, and a lens that focuses the light from the light source at a position corresponding to each wavelength. A reflector that is displaced in accordance with the displacement of the object to be measured on a line arranged in line and reflects light of a wavelength that is focused on a reflective surface as reflected return light, and a change in the spectral distribution of the reflected return light from the reflector. A displacement measuring device comprising: a spectrum distribution measuring section for detecting the spectrum distribution; and a displacement measuring section for measuring the displacement of the object based on the measurement result of the spectrum distribution.