JPH0583981U - Reflective photoelectric switch - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to eliminate an increase or decrease in sensitivity due to the length of the distance between the reflection type photoelectric switch and the reflection sheet in the reflection type photoelectric switch. [Structure] The light projecting element is the same as the conventional one, and the light receiving element has a light receiving surface which is sufficiently larger than the area of the light emitting portion of the light projecting element. ,
The light receiving area formed by the light receiving element and the optical system is sufficiently wide.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a configuration of a reflective photoelectric switch that detects opening / closing of a shutter or the like in a non-contact manner.

[0002]

[Prior Art]

 Conventionally, in this type of reflective photoelectric switch, as shown in FIG. 1, light is projected from the light projecting element 12 toward the retroreflective sheet 15 attached to the shutter 18 and reflected by the reflective sheet 15. The light is incident on the light receiving element 11, and the light receiving element 11 is slightly displaced from the focus position of the lens 13 (a little upward in the drawing) so that the light projecting range 16 and the light receiving range 17 intersect. It was Since the area of the light emitting part in the light projecting element 12 and the area of the part having light receiving sensitivity in the light receiving element 11 were about the same, the light projecting range 16 formed by the lenses 14 and 13 having the same focal length and the light receiving area. The spread angle of the range 17 was almost the same.

[0003]

[Problems to be solved by the device]

 In this type of reflective photoelectric switch, the reflective sheet is used so that the reflective sheet is located at the intersection of the light emitting area and the light receiving area.However, the distance between the reflective photoelectric switch and this reflective sheet is short. Whether it is too long or too long, the cross-sectional area at the intersection of the light projection range and the light reception range is extremely reduced, and the amount of reflected light is accordingly reduced. In other words, the light receiving sensitivity greatly changed depending on the distance.

[0004]

[Means for Solving the Problems]

 In the present invention, the conventional light emitting element is used as it is, and the light receiving element having a light receiving surface which is sufficiently larger than the area of the light emitting portion of the light emitting element is used to solve the conventional problems.

[0005]

[Action]

 Since the light receiving area is made sufficiently larger than the light emitting area, the cross-sectional area at the intersection of the light emitting area and the light receiving area remains large compared to the size of the reflection sheet. Can be less affected by.

[0006]

【Example】

 FIG. 2 shows a cross section of the reflective photoelectric switch of the present invention. The light projecting element 22 is an infrared light emitting diode, and emits pulsed light in response to a pulse signal supplied from an internal oscillation circuit. This light is reflected by the retroreflective sheet 25 attached to the shutter 28 and enters the light receiving element 21. The signal obtained from the light receiving element is processed through an internal amplification section and comparison section, and drives an output section such as a relay. The lenses 23 and 24 have the same shape for both light projection and light reception, but the light receiving element 21 is arranged at a position slightly displaced from the central axis X of the lens 23 as shown in FIG. The light receiving range 27 formed by the light receiving element 21 and the lens 23 is sufficiently wider than the light projecting range 26 formed by. Therefore, in the conventional example shown in FIG. 1, when the distance from the reflection type photoelectric switch to the reflection sheet 15 is shorter or longer than that in this figure, the portion where the light emitting range and the light receiving range intersect (indicated by the diagonal lines in the figure). 2), the ratio of the light occupying area to the reflection sheet 15 is reduced, but in the configuration of the present invention shown in FIG. 2, the light emitting range is the same as before, but the light receiving range is sufficiently larger than the light emitting range. Therefore, even when the distance from the reflection type photoelectric switch to the reflection sheet 25 is shortened or lengthened, the intersection of the light emitting range 26 and the light receiving range 27 can be kept constant in a certain constant section. The proportion of the reflection sheet 25 is the same in that section. In other words, the amount of light incident on the light receiving element 21 is long or short, even if the distance (warning distance) between the reflection type photoelectric switch body (including the light projecting portion and the light receiving portion) and the retroreflective sheet 25 is long or short. Since the (amount of light emitted from the light projecting element and reflected and returned) does not increase or decrease much, stable operation can be obtained at any distance.

[0007]

[Effect of the device]

 Since the reflection type photoelectric switch of the present invention has the light receiving range sufficiently wider than the light emitting range, the difference in sensitivity due to the warning distance can be eliminated. In addition, since the light-receiving range is made sufficiently large, the light-emitting element or the pellet of the light-receiving element is positioned at a position that is slightly displaced, and even if the light-emitting range or light-receiving range is slightly displaced, it occupies the reflection sheet of the intersecting area. The ratio did not change, and as a result, it was possible to prevent fluctuations in the amount of received light.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a conventional reflective photoelectric switch.

FIG. 2 is a cross-sectional view of the reflective photoelectric switch of the present invention.

[Explanation of symbols]

 21 Light receiving element 22 Light emitting element 23 Lens 24 Lens 25 Reflective sheet 26 Light emitting range 27 Light receiving range 28 Shutter

Claims (1)

[Scope of utility model registration request] A reflective photoelectric sensor that attaches a retroreflective sheet to the surface of a movable part such as a shutter, projects infrared rays, and receives the light reflected from this sheet and returned to the light-receiving part to detect the state of the movable part. In the switch, a light receiving element having a light receiving surface that is sufficiently larger than the pellet of the light projecting element is arranged, and the light receiving element and the optical system form a light projecting range formed by the light projecting element and the optical system. A reflective photoelectric switch characterized by a sufficiently wide light receiving range.