JPH063110A - Position detector - Google Patents

Abstract

PURPOSE:To enlarge the diameter of a light flux, to widen a range of detection and also to make excellent the uniformity of the light quantity distribution on the section of the light flux and the linearity of a signal, without making construction large in size, in a position detector which detects the position of displacement of an object of measurement by a light source and a photodetector. CONSTITUTION:The title detector is provided with a light source 4 and a first parabolic mirror which is positioned in the rear of the light source 4 and has a paraboloid reflecting a divergent light 4a of the light source 4 and making it a parallel light flux 4b. Moreover, it is provided, in its construction, with a second parabolic mirror 6 which has a paraboloid converging the parallel light flux 4b by reflection at a position corresponding to the paraboloid of the first parabolic mirror 5, and with a photodetector 7 which is disposed at a point of convergence and detects the position of an object 3 of measurement being displaced in such an intersecting manner as to intercept part of the parallel light flux 4b, from a change in the quantity of light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical position detecting device for detecting the position of a displaced object in a non-contact manner.

[0002]

2. Description of the Related Art FIG. 4 shows, for example, JP-A-60-13140.
It is a block diagram which shows the outline of the conventional position detection apparatus described in the 5th publication. In the figure, 1 is a light source such as a light emitting diode which emits light 1a, 2 is a photodetector arranged facing the light source 1, and here, a phototransistor 5 is a light source 1
The object to be measured is displaced between the light detector 2 and the light detector 2 so as to block the light 1a.

Next, the operation will be described. The light 1a emitted from the light source 1 travels while diverging, and is irradiated onto the photodetector. When the DUT 3 placed at a position that blocks this light 1a is displaced in the direction of the arrow in the figure, the amount of light emitted to the photodetector 2 changes, so the output signal of the photodetector 2 is the output signal of the DUT 3. It depends on the displacement. FIG. 5 is a graph showing the relationship between the variable position of the DUT 3 and the output signal of the photodetector 2 described above.

[0004]

Since the conventional position detecting device is configured as described above, since the divergent light is used as it is from the light source, the light amount distribution uniformity of the cross section of the light beam is poor. Therefore, as shown in FIG. 5, only an output with poor linearity can be obtained. Further, in order to widen the detection range, there is a problem that the distance between the light source and the object to be measured must be increased and the light receiving surface of the photodetector must be increased.

The present invention has been made in order to solve the above problems, and has a large luminous flux diameter, a wide detection range, a uniform light quantity distribution in a cross section of the luminous flux, and a good linearity of an output signal. The purpose is to obtain a detection device.

[0006]

A position detecting device according to the present invention comprises a light source and a first parabola located behind the light source and having a parabolic surface that reflects divergent light from the light source to form a parallel light beam. A face mirror and a second parabolic mirror having a parabolic surface for reflecting and condensing a light beam parallel to the parabolic surface of the first parabolic mirror are arranged at a condensing point and are parallel to each other. And a photodetector that detects the position of an object to be measured that intersects and displaces so as to block a part of the luminous flux by a change in the amount of light.

Further, an ellipsoidal mirror whose inner surface is an elliptical reflecting surface, a light source arranged at one of the two focal points of the ellipsoidal mirror to emit divergent light, and another light source disposed at the other focal point of the two focal points. It is composed of a photodetector for detecting the position of the object to be measured which changes so as to block a part of the divergent light between the focal points by a change in the light amount.

[0008]

In the position detecting device according to the present invention, the first parabolic mirror irradiates the object to be measured with a light beam in parallel, which improves the uniformity of the light amount distribution in the cross section of the light beam, and the second parabolic mirror. The light amount detection area of the photodetector can be reduced by condensing with.

[0009]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a block diagram showing an outline of a position detecting device according to a first embodiment of the present invention. In the figure, 4 is a light source such as a light emitting diode that emits divergent light 4a, and 5 is a first parabolic mirror located behind the light source 4 and having a parabolic surface that reflects the divergent light 4a into a parallel light beam 4b. , 6 is the first parabolic mirror 5
A second parabolic mirror having a parabolic surface for condensing the light beam 4b parallel to the position corresponding to the second parabolic mirror, and 7 is an object to be measured which is arranged at the condensing point of the second parabolic mirror 6 and is displaced. 3 is a photodetector such as a photodiode that detects the position of 3.

Next, the operation will be described. The divergent light 4a emitted from the light source 4 is reflected by the first parabolic mirror 5 and becomes a parallel light beam 4b. Further, it is focused on one point by the second parabolic mirror 6 and guided to the photodetector 7. When the DUT 3 placed so as to block a part of the parallel light beam 4b is displaced in the direction of the arrow in the figure, the amount of light reaching the photodetector 7 changes. Therefore, an output corresponding to the displacement of the DUT 3 is obtained. Note that FIG. 2 is a graph showing the relationship between the displacement amount of the DUT 3 and the output signal of the photodetector 7.

Embodiment 2. The second embodiment of the present invention will be described below with reference to FIG. In the figure, 8 is an ellipsoidal mirror whose inner surface is an elliptical reflecting surface, 9 is a light source such as a light emitting diode which is located at one focal point of the ellipsoidal mirror 8 and emits divergent light 9a, and 10 is the other of the ellipsoidal mirror 8. Is a photodetector such as a photodiode for detecting the position of the DUT 3 which is located at the focal point and is displaced across the focal points.

Next, the operation will be described. The ellipsoidal mirror has the property that the light emitted from one of the focal points reaches the other focal point in all directions. Therefore, if there is no DUT 3, all the divergent light 9a emitted from the light source 9 reaches the photodetector 10. When the device under test 3 is displaced in the direction of the arrow in the figure, the amount of light reaching the photodetector 10 changes, so that an output corresponding to the displacement of the device under test 3 is obtained. The relationship between the displacement amount of the DUT 3 and the output signal has the same tendency as FIG. 2 shown in the first embodiment.

[0013]

As described above, the position detecting device of the present invention includes the first parabolic mirror located behind the light source and having the parabolic surface that reflects the divergent light of the light source to form a parallel light beam. A second parabolic mirror having a parabolic surface for reflecting and condensing a light flux parallel to the parabolic surface of the first parabolic mirror, and one of the parallel light fluxes arranged at the converging point. Since it is composed of a photodetector that detects the position of the measured object that intersects and displaces so as to block the part by changing the amount of light, the luminous flux becomes parallel at the position of the measured object and the light amount distribution in the cross section becomes almost uniform. . In addition, an ellipsoidal mirror whose inner surface is an elliptical reflecting surface and an ellipsoidal mirror
A light source that is placed at one of the focal points and emits divergent light;
Since it is configured with a photodetector that is located at the other of the focal points and changes the position of the measured object between the focal points so as to block some of the divergent light, it is configured with a photodetector. The light beam diameter is large, the light amount distribution on the light beam cross section is uniform, and in each case, there is an effect that a position detection device having good linearity and a wide detection range can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of a position detection device according to a first embodiment of the present invention.

FIG. 2 is a graph illustrating an output signal of the device according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing an outline of a position detection device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram showing an outline of a conventional device.

FIG. 5 is a graph illustrating an output signal of a conventional device.

[Explanation of symbols]

 3 object to be measured 4 light source 4a divergent light 4b parallel light flux 5 first parabolic mirror 6 second parabolic mirror 7 photodetector 8 ellipsoidal mirror 9 light source 9a divergent light 10 photodetector

Claims (2)

[Claims] 1. A first parabolic mirror having a light source, a first parabolic mirror located behind the light source and having a parabolic surface that reflects divergent light from the light source to form a parallel light flux, and the first parabolic surface. A second parabolic mirror having a parabolic surface for converging the parallel light flux at a position corresponding to the parabolic surface of the mirror by reflection, and one of the parallel light fluxes arranged at the converging point. A position detector, comprising: a photodetector that detects the position of an object to be measured that intersects and displaces so as to block a portion by a change in the amount of light. 2. An ellipsoidal mirror whose inner surface is an elliptical reflecting surface, a light source arranged at one of the two focal points of the ellipsoidal mirror to emit divergent light, and another focal point of the other two focal points. A position detector comprising: a photodetector arranged to detect a position of an object to be measured, which is displaced between the two focal points so as to block a part of the divergent light, based on a change in the amount of light.