JPH09257470A - Optical displacement sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical displacement sensor which can measure a displacement highly accurately without generating measuring errors because of a partial reflected light from an object to be measured. SOLUTION: The sensor is provided with a light-projecting means 1 for projecting light beams to a surface of an object to be measured and forming projection light spots, a photodetecting means 2 for converging a reflecting light from the spots by a photodetecting lens 21 and outputting signals corresponding to a photodetecting position of a photodetecting element 22, and a light-transmitting plate 3 having a reflecting face 31 for reflecting a part of the reflecting light from the object to be measured. Light beams pass through the plate 3 while intersecting a light projection axis 1a. A displacement of the object to be measured in a projecting direction of light beams is measured according to the triangulation surveying a triangle of a light-projecting/receiving plane 12a defined by the light projection axis 1a of the light beams and a photodetecting axis 2a of the reflecting light. The reflecting face 31 of the plate 3 is inclined to the light-projecting/receiving plane 12a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a triangulation for measuring a displacement of an object to be measured in a light beam irradiation direction by measuring a triangle of a light projecting and receiving plane formed by a light beam projecting axis of a light beam and a light receiving axis of reflected light. The present invention relates to an optical displacement sensor that is measured by a method.

[0002]

2. Description of the Related Art Conventionally, as this type of optical displacement sensor,
6 and 7 exist. In this device, a light projecting means A for irradiating a light beam on the surface of the object to be measured to form a light projecting spot, and reflected light from the light projecting spot is converged by a light receiving lens B1 and a light receiving position B3 of a light receiving element B2.
Corresponding to the light receiving means B for outputting a signal, and the reflecting surface C2 for reflecting a part of the reflected light C1 from the object to be measured, the light beam crosses the light projecting axis A1 and is transmitted. Transparent plate C
And

More specifically, the light projecting means A is composed of a light source section A2 such as a semiconductor laser and a light projecting lens A3. When the reference surface of the object to be measured is displaced, the distance from the reference surface to the displacement surface is measured by a triangulation measuring the triangle of the projection / reception plane D formed by the projection axis A1 of the light beam and the reception axis B4 of the reflected light. It can be measured by the method.

That is, the length of the perpendicular line drawn from the center of the light receiving lens B1 to the light projecting axis A1, the light projecting axis A1 and the light receiving axis B4.
If the light receiving angle formed by and the distance between the light receiving lens B1 and the light receiving element B2 are set to constant values, the distance from the light receiving position B3 of the reflected light on the reference surface to the light receiving position on the displacement surface is measured. Therefore, the distance from the reference plane to the displacement plane, that is, the displacement amount can be measured.

[0005]

In the above-mentioned conventional optical displacement sensor, the displacement of the object to be measured from the reference plane can be measured by receiving the reflected light from the object to be measured.

However, the partially transparent light which is a part of the reflected light from the object to be measured intersects with the light projecting axis A1.
The reflected light of the light beam and the partially reflected light are present on the surface of the object to be measured.

As shown in FIG. 7, when a plurality of these light beams are converged by the light receiving lens B1 and formed an image on the light receiving surface of the light receiving element B2, the light receiving element forms an image forming position B3 of reflected light necessary for measurement.
The current corresponding to the position where the image formation position B5 of the partially reflected light and the image formation position is combined is output. This causes a measurement error. Here, when the surface of the light-transmitting plate is coated, the light-transmitting plate can reduce reflection of partially reflected light, but since it cannot be reduced to zero, a measurement error due to partially reflected light is unavoidable.

The present invention has been made in view of the above reasons, and an object thereof is to measure displacement with high accuracy without causing a measurement error due to partially reflected light from the object to be measured. An object is to provide an optical displacement sensor that can be used.

[0009]

In order to solve the above-mentioned problems, according to a first aspect of the present invention, a light projecting means for irradiating a surface of an object to be measured with a light beam to form a light projecting spot, and a light projecting means. It has a light receiving unit that converges the reflected light from the light spot with a light receiving lens and outputs a signal corresponding to the light receiving position of the light receiving element, and a reflecting surface that partially reflects the reflected light from the DUT. And a light-transmitting plate through which the light beam crosses the light-projecting axis, and the displacement of the DUT in the light-beam irradiation direction is formed by the light-beam projecting axis and the reflected-light receiving axis. In an optical displacement sensor for measuring by a triangulation method for measuring a triangle of a light emitting and receiving plane, the reflecting surface of the light transmitting plate is provided so as to be inclined with respect to the light emitting and receiving plane.

According to a second aspect of the present invention, in the light transmitting plate according to the first aspect, the partially reflected light reflected from the reflecting surface is coupled to the surface of the object to be measured by the light receiving lens. The reflecting surface is provided so as to be inclined so as to enter the outside of the imaged image of the light receiving element.

According to a third aspect of the present invention, a light projecting means for irradiating a surface of the object to be measured with a light beam to form a light projecting spot, and a light receiving lens for converging reflected light from the light projecting spot by a light receiving lens. The light transmitting means for outputting a signal corresponding to the light receiving position and the reflecting surface for reflecting a part of the reflected light from the object to be measured and transmitting the light beam through the projection axis. A light plate is provided, and the displacement of the DUT in the light beam irradiation direction is measured by the triangulation method that measures the triangle of the light emitting and receiving plane formed by the light beam emitting axis and the reflected light receiving axis. In the optical displacement sensor, the translucent plate is configured so that the partially reflected light reflected from the reflecting surface enters outside the range of the light receiving element image formed on the surface of the object to be measured by the light receiving lens. , The structure in which the reflecting surface is provided to be inclined with respect to the projection axis And Aru.

According to a fourth aspect of the present invention, in the third aspect, the translucent plate has a side of the light receiving lens side with respect to the light projecting axis, among angles formed by the reflecting surface and the light projecting axis. The angle on the opposite side is obtuse.

According to a fifth aspect of the present invention, a light projecting means for irradiating a surface of the object to be measured with a light beam to form a light projecting spot, and a light receiving element for converging light reflected from the light projecting spot by a light receiving lens. The light transmitting means for outputting a signal corresponding to the light receiving position and the reflecting surface for reflecting a part of the reflected light from the object to be measured and transmitting the light beam through the projection axis. A light plate is provided, and the displacement of the DUT in the light beam irradiation direction is measured by the triangulation method that measures the triangle of the light emitting and receiving plane formed by the light beam emitting axis and the reflected light receiving axis. In the optical displacement sensor, the light-transmitting / receiving plane and the light-projecting plane are arranged so that the reflecting surface of the light-transmitting plate enters outside the range of the light-receiving element image formed on the surface of the object to be measured by the light-receiving lens. It is configured so as to be inclined with respect to the axis.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

A light projecting means 1 is provided with a light source section 11 made of a semiconductor laser or a light emitting diode and a light projecting lens 12 made of transparent resin, and a light beam emitted from the light source section 11 is a parallel light beam by the light projecting lens 12. As a bundle, the surface of the object to be measured is irradiated with a light beam to form a light projection spot.

Reference numeral 2 denotes a light receiving means, which is provided with a light receiving lens 21 made of a transparent resin and a light receiving element 22 made of a position detecting element, and the reflected light from the projected spot is converged by the light receiving lens 21 to be received by the light receiving element 22. Image on the surface
2 outputs two kinds of current signals to both ends corresponding to the image forming position 22a, that is, the light receiving position. Further, the light beam projecting axis 1a and the reflected light receiving axis 2a are formed by the projecting and receiving plane 12a.
Are arranged so that the light receiving surface of the light receiving element 22 is orthogonal to the light projecting and receiving plane 12a.

The light receiving element 22 receives two types of electric currents by receiving the reflected light of the light beam and outputting them. The difference between the two current outputs corresponds to the image forming position on the light receiving surface of the light receiving element 22, and
The sum of both current outputs corresponds to the total amount of light received and is constant in this case. Therefore, the division value obtained by dividing the difference between both current outputs by the sum of both current outputs becomes the value corresponding to the image forming position.

Reference numeral 3 denotes a light-transmitting plate, which is made of glass or transparent resin that transmits light, and a part of the reflected light 23 reflected from the surface of the object to be measured is reflected by the light beam. It has a surface 3131 and is provided so as to intersect with the light projecting axis 1a and seal the opening. It has a dustproof and waterproof function, and transmits a light beam.

The reflecting surface 31 is provided so as to be inclined with respect to the light emitting / receiving plane 12a formed by the light beam projecting axis 1a and the reflected light receiving axis 2a, and is reflected from the reflecting surface 31. The partially reflected light 23 is inclined so that the light receiving element 22 does not enter the range 24 of the light receiving element image which is converged by the light receiving lens 21 and formed on the surface of the object to be measured, that is, it enters outside the range 24. Is provided.

Here, the partially reflected light 23 is reflected by the transparent plate 3 and is reflected again by the object to be measured. However, the reflecting surface 3 of the translucent plate 3 is arranged so that the partially reflected light 23 enters outside the range 24 of the light receiving element image formed on the surface of the object to be measured.
1 is inclined with respect to the light emitting / receiving plane 12a, the partially reflected light 23 reflected again is received by the light receiving element 22.
No image is formed on the light receiving surface of. Further, since the reflecting surface 31 is inclined with respect to the light projecting / receiving plane 12a, the optical axis of the partially reflected light 23 reflected again deviates from the light projecting / receiving plane 12a.

The operation of the above will be described. When the reference surface of the object to be measured is displaced in the irradiation direction of the light beam, the image forming position of the object to be measured formed on the light receiving surface of the light receiving element 22 moves. The movement amount of the image forming position of the object to be measured is determined by the light receiving element 22.
Based on the output of the above, the distance calculation means (not shown) calculates and obtains
It is possible to measure the distance from the reference plane of the object to be measured in the irradiation direction of the light beam to the reference plane and the displaced plane.

In the optical displacement sensor of the first embodiment, as described above, the partially reflected light 23 reflected from the reflecting surface 31 is imaged on the surface of the object to be measured by the light receiving lens 21. Since the reflecting surface 31 of the translucent plate 3 is provided so as to be inclined with respect to the light projecting / receiving plane 12a so as not to enter the image range 24, that is, to enter the outside of the range 24, the partially reflected light 23 is received. The displacement can be measured with high accuracy by reducing the measurement error without forming an image on the light receiving surface of 22.

In the first embodiment, the partially reflected light 23
However, the reflection surface 31 is provided so as to be inclined with respect to the light emitting and receiving plane 12a so as to enter the outside of the range 24 of the light receiving element image formed on the surface of the object to be measured. May be.

In this case, as shown in FIG. 4, the partially reflected light 23 forms an image on the light receiving surface of the light receiving element 22 at the image forming position 22b. However, since the reflecting surface 31 is inclined with respect to the light projecting / receiving plane 12a, the optical axis of the partially reflected light 23 reflected again by the object to be measured is deviated from the light projecting / receiving plane 12a, and the image forming position 22b is formed. Is positioned in a direction orthogonal to the detection direction for detecting the position of the light receiving surface.
Therefore, the light receiving element 22 can output a signal corresponding to the light receiving position 22a with a small error to reduce the measurement error and measure the displacement.

A second embodiment of the present invention will be described below with reference to FIG. In the second embodiment, functions different from those in the first embodiment will be described, and members having substantially the same functions as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

In the translucent plate 3, among the angles formed by the reflecting surface 31 and the light projecting axis 1a, the angle on the side opposite to the light receiving lens 21 side with respect to the light projecting axis 1a is an obtuse angle and is reflected from the reflecting surface 31. The partially reflected light 23 is tilted with respect to the projection axis 1a of the light beam so that the light receiving element 22 enters outside the range 24 of the light receiving element image formed on the surface of the object to be measured by the light receiving lens 21. It is provided.

Here, the partially reflected light 23 is reflected by the transparent plate 3 and is reflected again by the object to be measured. However, the reflecting surface 3 of the translucent plate 3 is arranged so that the partially reflected light 23 enters outside the range 24 of the light receiving element image formed on the surface of the object to be measured.
1 is inclined with respect to the projection axis 1a,
The partially reflected light 23 reflected again does not form an image on the light receiving surface of the light receiving element 22.

Further, the light receiving lens 21 with respect to the light projecting axis 1a.
Since the angle on the side opposite to the side is an obtuse angle, the partially reflected light 23 is incident on the surface of the DUT located away from the light receiving lens 21 with respect to the projection axis 1a, and only the partially reflected light 23 is present. However, the probability that scattered light resulting from the incidence of the partially reflected light 23 on the object to be measured is incident on the light receiving lens 21 is reduced.

In the optical displacement sensor according to the second embodiment, as described above, the partially reflected light 23 reflected from the reflecting surface 31 is imaged on the surface of the object to be measured by the light receiving lens 21. The reflection surface 31 of the translucent plate 3 is provided so as to be inclined with respect to the projection axis 1a so that it does not enter the area 24, that is, outside the range 24.
Does not form an image on the light receiving surface of the light receiving element 22, the measurement error can be reduced, and the displacement can be measured with high accuracy.

Further, among the angles formed by the reflecting surface 31 and the light projecting axis 1a, the angle of the light transmitting plate 3 on the side opposite to the light receiving lens 21 side with respect to the light projecting axis 1a is an obtuse angle, so that a part of the reflected light is reflected. 23 is incident on the surface of the object to be measured located away from the light receiving lens 21 with respect to the projection axis 1a, and not only the partially reflected light 23 but also scattered light resulting from the incidence of the partially reflected light 23 is received by the light receiving element. 22
The probability of forming an image on the light receiving surface of is reduced, and the measurement error can be further reduced.

In the second embodiment, of the angles formed by the reflecting surface 31 and the light projecting axis 1a, the angle on the side opposite to the light receiving lens 21 side with respect to the light projecting axis 1a is an obtuse angle, and some reflection occurs. The range 24 of the light receiving element image in which the light 23 is formed on the surface of the DUT.
The light-transmitting plate 3 is provided so as to be inclined with respect to the projection axis 1a of the light beam so as to be incident to the outside, but when the scattered light resulting from the incidence of the partially reflected light 23 on the surface of the object to be measured is small. The angle on the side opposite to the light receiving lens 21 side with respect to the light projecting axis 1a does not have to be an obtuse angle.

Further, in the second embodiment, among the angles formed by the reflecting surface 31 and the light projecting axis 1a, the angle on the side opposite to the light receiving lens 21 side with respect to the light projecting axis 1a is an obtuse angle and partially reflected. The range 24 of the light receiving element image in which the light 23 is formed on the surface of the DUT.
The light-transmitting plate 3 is provided so as to be inclined with respect to the projection axis 1a of the light beam so that the light-transmitting plate 3 is further incident in this state.
The reflecting surface 31 may be inclined with respect to the light emitting / receiving plane 12a, and is not limited.

[0033]

According to the first aspect of the present invention, since the reflecting surface of the translucent plate is provided so as to be inclined with respect to the light emitting / receiving plane, the optical axis of the partially reflected light reflected again by the object to be measured is light emitting / receiving. Even if a part of the reflected light forms an image on the light receiving surface of the light receiving element because it is out of the plane, it forms an image in the direction orthogonal to the detection direction for detecting the image forming position on the light receiving surface, Can output a signal corresponding to the light receiving position with a small error, reduce the measurement error, and measure the displacement with high accuracy.

According to the second aspect, in addition to the effect of the first aspect, the partially reflected light reflected from the reflecting surface is
Since the reflecting surface of the light-transmitting plate is provided so as not to enter the range of the light-receiving element image formed on the surface of the object to be measured by the light-receiving lens, that is, to enter outside the range, part of the reflected light It is possible to further reduce the measurement error without forming an image on the light receiving surface of the light receiving element.

According to the third aspect of the present invention, the partially reflected light reflected from the reflecting surface is prevented from entering the light receiving element image formed on the surface of the object to be measured by the light receiving lens, that is, outside the range. Since the reflecting surface of the translucent plate is inclined with respect to the projection axis, a part of the reflected light does not form an image on the light receiving surface of the light receiving element, and the measurement error is reduced to measure the displacement with high accuracy. be able to.

According to a fourth aspect of the invention, in addition to the effect of the third aspect, among the angles formed by the reflecting surface and the projection axis,
Since the angle of the translucent plate on the side opposite to the light receiving lens side with respect to the light emitting axis is an obtuse angle, part of the reflected light is incident on the surface of the DUT located away from the light receiving lens with respect to the light emitting axis. As a result, the probability that not only partially reflected light but also scattered light resulting from the incidence of partially reflected light will form an image on the light receiving surface of the light receiving element, and the measurement error can be further reduced.

According to a fifth aspect of the present invention, the light emitting / receiving plane and the light projecting axis are arranged so that the reflecting surface of the light transmitting plate enters outside the range of the light receiving element image formed on the surface of the object by the light receiving lens. Since it is provided so as to be inclined, the reflected light is not focused on the light receiving surface of the light receiving element, the measurement error can be reduced, and the displacement can be measured with high accuracy.

[Brief description of drawings]

FIG. 1 is a projection / reception plane 12a showing a first embodiment of the present invention.
It is the front view seen from the orthogonal direction with respect to.

FIG. 2 is a bottom view seen from a direction parallel to the light emitting / receiving plane 12a of the above.

FIG. 3 is a bottom view showing an image formation state of partially reflected light 23 viewed from a direction parallel to the light projecting / receiving plane 12a.

FIG. 4 is an image forming state diagram showing an image forming state on a light receiving surface of the above light receiving element 22.

FIG. 5 is a projection / reception plane 12a showing a second embodiment of the present invention.
It is the front view seen from the orthogonal direction with respect to.

FIG. 6 is a front view of a conventional example seen from a direction orthogonal to a light projecting / receiving plane 12a.

FIG. 7 is a correspondence diagram between the image forming position on the light receiving surface of the light receiving element 22 and the light intensity of the image forming light.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light emitting means 1a Light emitting axis 12a Light emitting / receiving plane 2 Light receiving means 2a Light receiving axis 21 Light receiving lens 22 Light receiving element 23 Partially reflected light 24 Range 3 Light transmitting plate 31 Reflective surface

Claims (5)

[Claims] 1. A light projecting means for irradiating a surface of an object to be measured with a light beam to form a light projecting spot, and light reflected from the light projecting spot is converged by a light receiving lens to correspond to a light receiving position of a light receiving element. And a light-transmitting plate through which a light beam crosses the projection axis and transmits light, the light-receiving unit outputting a signal and outputting a signal, and having a reflecting surface for reflecting a part of the reflected light from the object to be measured. In an optical displacement sensor for measuring the displacement of the measured object in the light beam irradiation direction by a triangulation method for measuring a triangle of a light projecting / receiving plane formed by a light beam projecting axis and a reflected light receiving axis, An optical displacement sensor, wherein the reflecting surface of the light transmitting plate is provided to be inclined with respect to the light emitting and receiving plane. 2. The light-transmitting plate is configured such that the partially reflected light reflected from the reflecting surface enters outside the range of the light-receiving element image formed on the surface of the DUT by the light-receiving lens. The optical displacement sensor according to claim 1, wherein the reflection surface is provided so as to be inclined. 3. A light projecting means for irradiating a surface of an object to be measured with a light beam to form a light projecting spot, and light reflected from the light projecting spot is converged by a light receiving lens to correspond to a light receiving position of a light receiving element. And a light-transmitting plate through which a light beam crosses the projection axis and transmits light, the light-receiving unit outputting a signal and outputting a signal, and having a reflecting surface for reflecting a part of the reflected light from the object to be measured. In an optical displacement sensor for measuring the displacement of the measured object in the light beam irradiation direction by a triangulation method for measuring a triangle of a light projecting / receiving plane formed by a light beam projecting axis and a reflected light receiving axis, The translucent plate has the reflecting surface so that the partially reflected light reflected from the reflecting surface enters outside the range of the light receiving element image formed on the surface of the object to be measured by the light receiving lens. An optical displacement cell characterized by being provided so as to be inclined with respect to the projection axis. Support. 4. The light-transmitting plate is characterized in that, among angles formed by the reflecting surface and the light-projecting axis, an angle on the side opposite to the light-receiving lens side with respect to the light-projecting axis is an obtuse angle. The optical displacement sensor according to claim 3. 5. A light projecting means for irradiating a surface of an object to be measured with a light beam to form a light projecting spot, and light reflected from the light projecting spot is converged by a light receiving lens to correspond to a light receiving position of a light receiving element. And a light-transmitting plate through which a light beam crosses the projection axis and transmits light, the light-receiving unit outputting a signal and outputting a signal, and having a reflecting surface for reflecting a part of the reflected light from the object to be measured. In an optical displacement sensor for measuring the displacement of the measured object in the light beam irradiation direction by a triangulation method for measuring a triangle of a light projecting / receiving plane formed by a light beam projecting axis and a reflected light receiving axis, The reflecting surface of the translucent plate is tilted with respect to the light projecting and receiving plane and the light projecting axis so that the reflecting surface is incident outside the range of the light receiving element image formed on the surface of the object to be measured by the light receiving lens. An optical displacement sensor characterized by being provided as.