JPH04101336U - photoelectric switch - Google Patents

Abstract

(57) [Summary] [Purpose] A photoelectric switch that accurately detects the presence or absence of an object in a detection space without being affected by reflected light from non-detection reflecting objects in the detection space. [Structure] This is a photoelectric switch in which a light emitter and a light receiver are placed facing each other with a detection space in between, and a vertical polarizing filter is placed at the light entrance of the light receiver. The polarizing filter cuts off reflected light from a reflective object, which is a non-detection object, located near the object in the detection space, out of the light projected from the projector.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This idea uses light to optically detect the presence or absence of an object in a predetermined detection space. For details regarding the power switch, please refer to the following for details. The present invention relates to a transmission type photoelectric switch that is effective for manufacturing equipment where an exit space exists.

0002

[Conventional technology]

Conventional structure of a transmission type photoelectric switch that detects the presence or absence of an object in a predetermined detection space will be explained with reference to FIG. This photoelectric switch detects the object (4) to be detected. A pair of emitters (5) and receivers (6) are installed on both sides of the detection space (m) for detecting the presence or absence of ) are placed. The floodlight (5) transmits an infrared beam (A) through a lens (7). It has a light projecting element (1) that projects light toward a light receiver (6) through the light receiving device. The receiver (6) is , are arranged opposite to the projector (5) with their optical axes aligned. The light receiver (6) is a light emitter ( The beam light (A) from 5) is received through the lens (8) and sent to the detection circuit (9). It has a light receiving element (2) that outputs an electrical signal.

0003 An object (4) is on the optical axis of the emitter (5) and receiver (6) in the detection space (m). If so, the object (4) will receive a beam of light (A) projected from the emitter (5) to the receiver (6). ). At this time, the light receiving element (2) of the light receiver (6) does not output an electrical signal. , the presence of an object in the detection space (m) is detected. Object (4) in detection space (m) If there is no light beam (A) from the projector (5), it will pass through the detection space (m). The light is received by the light receiver (6), and the light receiving element (2) outputs an electrical signal to detect the absence of an object. be done.

0004

[Problem that the idea aims to solve]

The infrared beam (A) projected from the projector (5) has a certain directivity angle α. It has directivity, and the light receiver (6) is sensitive to incident light from a certain directivity angle β. Both of these A detection space (m) is set in the area where the light projection angle α region of the person and the light incidence angle β region overlap. By this, the presence or absence of the object (4) in the detection space (m) is detected. On the other hand, photoelectric switch There are various types of manufacturing equipment where switches are used, which are installed on the floor or near walls. There is a reflective object (3), which is a non-detectable object such as a floor or wall, in the detection space (m) of the photoelectric switch. Often exists.

[0005] The reflective object (3) is, for example, a non-metallic floor with a smooth light-reflecting surface. A part of the light is located in the detection space (m) approximately parallel to the optical axis of the projector (5). A part of the spread area of the beam light (A) from the projector (5) is reflected by the object (3). The reflected light (B) enters the light receiver (6), and the light receiver (6) senses it. Sometimes. Then, there is no problem if there is no object (4) in the detection space (m), but When an object (4) exists in the detection space (m), the reflected light from the reflective object (3) ( Due to the sensitivity of the photoreceiver (6) caused by B), the photoelectric switch does not detect the presence of an object. This may cause erroneous detection of the presence of the ing.

[0006] As a solution to this problem, for example, a light beam (A) can be placed in front of the projector (5). By arranging a diaphragm slit to narrow the projection angle, or by adjusting the beam light (A ) The reflective surface is painted black or treated with matte treatment in some cases. There is. However, these solutions are difficult to adapt to various usage environments. There is another problem, and it is not very effective in increasing the reliability of photoelectric switches.

[0007]

[Means to solve the problem]

This idea uses reflected light from a reflective object that is a non-detection object existing in the detection space. In order to achieve the purpose of preventing malfunction, the light from the light emitting element is A photoelectric switch that transmits light through the detection space near the projectile and receives it on the light receiving element. The light from the emitter element is mainly composed of horizontally polarized light components reflected from the reflective object. It is characterized by the addition of a vertical polarizing filter that blocks the transmission of reflected light. shall be.

[0008]

[Effect]

This idea utilizes the following properties of light. In other words, in a photoelectric switch The light from the light emitting element is unbiased, consisting of a horizontally polarized component and a vertically polarized component. This random light is generated by non-metallic surfaces with smooth reflective surfaces such as floors and walls. The reflected light reflected from a reflective object of the genus has the physical property that it is mainly horizontally polarized light. do. Therefore, it is recommended to place a vertical polarizing filter in the light incidence path on the photodetector side. Then, the vertically polarized light among the random light from the light emitting element will be polarized in the same vertical direction. It passes through a polarizing filter and enters the photodetector, and a photoelectric switch detects the desired normal operation. make a work On the other hand, the random light from the light emitting element is reflected by a non-measurable reflective object. When the incident light reaches the polarizing filter, this reflected light is horizontally polarized light, so it becomes vertically polarized. It is cut by a direct polarizing filter and does not enter the light receiving element. This results in Malfunction of the photoelectric switch due to unwanted reflected light is prevented.

[0009]

【Example】

An embodiment of this invention will be described based on FIG. In addition, Figure 2 of the photoelectric switch in Figure 1 The same or equivalent parts are given the same reference numerals, and the explanation will be omitted.

0010 The difference between the embodiment of FIG. 1 and the photoelectric switch of FIG. 2 is that the light entrance of the light receiver (6) This is because a vertical polarizing filter (10) has been added to the. This vertical orientation The polarizing filter (10) filters the beam light (A) from the projector (5) and the reflective object (3). ) of the reflected light (B), the vertically polarized light is transmitted, but the horizontally polarized light is transmitted. is the polarizer to be cut. The polarizing filter (10) adjusts the light incidence angle of the receiver (6). The reflected light (B) from at least the central part of the β region where the optical axis is located is incident. It is placed in the area where it is located.

[0011] Infrared beam light (A) is emitted from the light emitting element (1) of the light emitter (5) into the inspection space (m ) towards the receiver (6), a non-metallic reflective object ( 3), the receiver (6) can be inspected without being affected by the reflected light (B). To accurately detect the presence or absence of an object (4) in space (m). In other words, in the inspection space (m) When there is an object (4), the light near the optical axis of the beam light (A) is blocked by the object (4). and does not reach the receiver (6). Also, at this time, if the beam light (A) is separated from the optical axis, A part of the spread light is reflected by the reflective object (3), and the reflected light (B) is reflected by the light receiver (6). ), this reflected light (B) is horizontally polarized light, so it is reflected vertically at the receiver (6). It is cut by a direct polarizing filter (10). As a result, the photoreceiver (6) becomes Detects the presence of an object. If there is no object (4) in the inspection space (m), the beam light (A) passes through the inspection space (m) and reaches the receiver (6), and its vertically polarized light component The light passes through the polarizing filter (10) and is received by the light receiving element (2). outputs an electric signal to the detection circuit (9), and the absence of an object is detected. The reaction at this time The presence or absence of reflected light (B) from the projectile object (3) has no effect on the receiver (6). stomach.

0012

[Effect of the idea]

According to this idea, there is a non-detection reflecting object along the inspection space, and this reflection Even if an object reflects the light from the emitter to the receiver, this reflected light has a horizontally polarized component. Since the light is mainly composed of The light is cut by the router and does not enter the light receiving element. Therefore, there are no non-detectable objects in the inspection space. Detecting the presence or absence of an object in the inspection space is always accurate, regardless of the presence or absence of a reflective object. A highly reliable photoelectric switch can be provided. Also, the direction perpendicular to the photodetector side is Simply attach a directional polarizing filter, and it can be used in environments with various reflective objects. It is possible to provide a highly versatile photoelectric switch that is easy to adapt to.

[Brief explanation of drawings]

[Fig. 1] A front view showing an embodiment of the photoelectric switch according to this invention.

[Figure 2] Front view of a conventional photoelectric switch

[Explanation of symbols]

1 Light projecting element 2 Light receiving element 3 Reflective object 10 Vertical polarizing filter

Claims (1)

[Scope of utility model registration request] 1. A photoelectric switch that transmits light from a light emitting element through a detection space near a reflective object that is a non-detection object and is received by a light receiving element, the light emitting element being on the side of the light receiving element. 1. A photoelectric switch characterized in that a vertically polarizing filter is attached for blocking the transmission of reflected light whose main component is a horizontally polarized component that is reflected from the reflective object.