JP3102138B2 - Photoelectric switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regression for detecting the presence or absence of an object by discriminating a change in the amount of light received when an object blocks an optical path which reaches a light receiving element after light emitted from a light emitting element is reflected by a reflector. The present invention relates to a reflection type photoelectric switch.

[0002]

2. Description of the Related Art FIG. 3 shows a side view of a light beam in a conventional photoelectric switch. In this case, the light projecting unit 3 and the light receiving unit 6 are located at upper and lower positions on the front of the case. Here, the photoelectric switch is a light projecting unit 3 including a light projecting element 1 and a light projecting lens 2, and a light receiving element 4
And a light receiving unit 6 comprising a light receiving lens 5 and a reflector 7, and a light projecting beam 8 and a light receiving beam 9 emitted from the light projecting unit 3.
Do not overlap at a distance close to the light projecting unit 3 and the light receiving unit 6, so that a part of the beam overlaps at a long distance, and the optical axis 10 of the light projecting unit 3 and the optical axis 11 of the light receiving unit 6 project. The parts 3 and 3 are arranged so as to expand as the distance from the light receiving part 6 increases. FIG. 4 is a sectional view taken along the arrow A in FIG. With this arrangement, light emitted from the light projecting element 1 is emitted via the light projecting lens 2 and reaches the reflector 7. The light reflected by the reflector 7 is condensed by the light receiving lens 5 and enters the light receiving element 4 where it is converted into an electric signal. At this time,
When an object passes between the light receiving section 6 and the reflector 7 and interrupts the optical path, the amount of light reaching the light receiving element 4 decreases, so that the electric signal changes. The presence or absence of an object is detected based on the change in the electric signal.

Here, the reason why the light projecting beam 8 and the light receiving beam 9 are not overlapped at a distance close to the light projecting portion 3 and the light receiving portion 6 is that the object has a high reflectance such as a white plane or a mirror. In this case, if the light passes through a distance close to the light projecting lens 2, the light reflected directly from the object enters the light receiving element 4 and malfunctions, so that this is avoided.

[0004]

In such a photoelectric switch, the angle between the light projecting beam 8 and the light receiving beam 9 is widened (the light projecting optical axis 10 and the light receiving optical axis 11 are not parallel). (Distance between part 3, light receiving part 6 and reflector 7)
In order to lengthen the length, the area of the reflector 7 must be increased to increase the amount of reflected light. For this reason, when trying to install a plurality of photoelectric switches side by side, there is a problem that the interval between adjacent photoelectric switches cannot be narrowed to be installed.

SUMMARY OF THE INVENTION In view of the above-described problems, an object of the present invention is to provide a photoelectric switch which is configured to be able to be installed with a small distance between adjacent photoelectric switches without increasing the area of the reflector. To provide.

[0006]

According to the present invention, there is provided a light projecting unit for emitting light emitted from a light projecting element via a light projecting lens,
A reflector that reflects the emitted light; and a light receiving unit that is arranged in parallel with the light projecting unit, receives light reflected by the reflector by a light receiving lens, and guides the light to a light receiving element. In a retroreflective photoelectric switch that detects the presence or absence of an object by a change in the amount of light received by a light receiving unit when the object passes through the space with the reflector, the curvature of at least one of the light projecting lens and the light receiving lens is determined by changing the curvature of the lens. The light beam from the lens was selected so as to spread in the arrangement direction of the light projecting lens and the light receiving lens and to be parallel to the direction perpendicular to the arrangement direction.

[0007]

According to the present invention, at least one of the light projecting lens and the light receiving lens has a different curvature in the horizontal direction and the vertical direction. Are parallel to each other in a direction perpendicular to the arrangement direction. Therefore, the cross-sectional area of the portion where the light beam from the light projecting lens and the light beam from the light receiving lens overlap is reduced.

[0008]

FIG. 1 shows an embodiment of the present invention, in which the same reference numerals as in FIG. 3 denote the same parts. FIG. 1 is a plan view of a light beam in a state where the light projecting unit 3 is arranged vertically above the light receiving unit 6 on the same vertical plane (in FIG. 3, a state where the light projecting unit 3 is horizontally arranged in the same vertical plane). is there. FIG. 2 is a sectional view of the light beam shown in FIG. 1 cut in a vertical direction.

In this embodiment, the horizontal curvatures of the light projecting lens 2 and the light receiving lens 5 are determined so that the light projecting beam 8 and the light receiving beam 9 become parallel and do not spread forward. The curvature in the vertical direction of the two lenses 2 and 5 is set to have a curvature similar to that of the conventional example shown in FIG.
This is the same as the curvature of the conventional two lenses 2 and 5. As a result, the sectional shapes of the light projecting beam 8 and the light receiving beam 9 become elliptical as shown in FIG.

The effective portion (hatched portion 12) where the projected beam 8 and the received beam 9 overlap has a smaller area compared to the conventional case, but the ratio of the effective portion to the entire beam area is smaller than that of the conventional case. Therefore, the amount of light returning to the light receiving element 4 is the same. Therefore, even if the reflector 7 having a small area is used, the same detection distance as that of the related art can be obtained. In addition, since the beam spread and the reflector 7 can be reduced, the intervals LA and LB can be shortened when the plurality of photoelectric switches are arranged side by side in FIG.

[0011]

According to the present invention, a lens having different curvatures in the horizontal direction and the vertical direction is used to spread a light beam emitted from the lens in the direction in which the light projecting lens and the light receiving lens are arranged. Since the reflectors are parallel to each other at right angles, even if the distance between the light emitting part and the light receiving part and the reflector is long, an object can be detected using a small-sized reflector. Further, since the reflector is small and the light beam is kept parallel so as to spread in the direction perpendicular to the arrangement direction, the installation interval when a plurality of photoelectric switches are arranged side by side can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of a light beam according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the light beam shown in FIG. 1 cut in a vertical direction.

FIG. 3 is a side view of a light beam in a conventional photoelectric switch.

FIG. 4 is a sectional view taken along the line AA of FIG. 3;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light emitting element 2 light emitting lens 3 light emitting part 4 light receiving element 5 light receiving lens 6 light receiving part 7 reflector 8 light beam 9 light beam

Claims (1)

(57) [Claims] 1. A light projecting unit for emitting light emitted from a light projecting element via a light projecting lens, a reflector for reflecting the emitted light, and a reflected light from the reflector arranged in parallel with the light projecting unit. A light receiving unit that receives light through a light receiving lens and guides the light to a light receiving element. The presence or absence of an object is determined by a change in the amount of light received by the light receiving unit when the object passes through the space between the light emitting unit and the light receiving unit and the reflector. In a recursive reflection type photoelectric switch that detects the light, the curvature of at least one of the light projecting lens and the light receiving lens is set so that the light beam from the lens is expanded in the arrangement direction of the light projecting lens and the light receiving lens. A photoelectric switch, which is selected so as to be parallel to a direction perpendicular to the arrangement direction.