JPH0679049U - Reflective photoelectric switch - Google Patents

Abstract

(57) [Summary] [Purpose] Stable and highly reliable operation by measuring the distance to the object to be detected regardless of the reflectance and correcting the detection signal value obtained from the received light amount. Realizes a reflective photoelectric switch. A reflective photoelectric switch for detecting the presence or absence of the detected object by irradiating the detected object with light emitted from a light projecting element and receiving reflected light from the detected object by a light receiving element. The light receiving elements are arranged on the light receiving axis and at positions displaced from the light receiving axis, respectively, and the object to be detected is detected from detection signals from the plurality of light receiving elements.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a reflective photoelectric switch, and more particularly to a reflective photoelectric switch that is less susceptible to changes in the distance to an object to be detected and reflectance.

[0002]

[Prior art]

 As shown in FIG. 3, the conventional reflection type photoelectric switch irradiates the light emitted from the light projecting element to an unillustrated object to be detected through a light projecting lens, and reflects light from the object to be detected through a light receiving lens. Light is received by the light receiving element, and the presence or absence of the detected object is detected by the received light signal.

Here, since the conventional device shown in FIG. 3 has a compound eye configuration, the relationship between the distance to the detected object and the amount of received light is as shown in FIG. The characteristics in Fig. 4 show the relationship between the amount of reflected light received and the distance to the detected object when the detected object is a white paper and a black paper, and the characteristics are clearly different. I understand. For this reason, even if the same object is located at different distances or with different reflectivities, abnormal detection occurs. In other words, even if there was an object to be detected, it could be judged as "none."

[0004]

[Problems to be solved by the device]

 The present invention has been made in view of the above-mentioned problems of the prior art, and measures the distance to the detected object regardless of the reflectance and corrects the detection signal value obtained from the received light amount. By so doing, it is intended to provide a reflective photoelectric switch that operates stably and has high reliability.

[0005]

[Means for Solving the Problems]

 The configuration of the present invention for solving the above-mentioned problems is achieved by irradiating the light emitted from the light projecting element to the detected object and receiving the reflected light from the detected object by the light receiving element. In the reflective photoelectric switch for detecting the presence or absence of the light receiving element, the light receiving elements are arranged on the light receiving axis and at positions deviated from the light receiving axis, and the detected object is detected from the detection signals from the plurality of light receiving elements. It is characterized by being configured.

[0006]

[Action]

 According to the present invention, the outputs of a plurality of light receiving elements are calculated, distance detection is performed without depending on the reflectance of the object, and the light reception output is corrected by the distance measurement value.

[0007]

【Example】

 Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the reflection type photoelectric switch of the present invention. In FIG. 1, 1 is a light projecting element such as an LED, 2 is a collimator lens that makes the light emitted from the light projecting element 1 normal light, 3 is a half mirror, 4 is an object to be detected, and 5 is arranged on the optical axis. The light receiving element 6 is a light receiving element which is arranged so as to be displaced from the optical axis.

In such a configuration, the outputs I _PD1 and I _PD2 of the light receiving elements 5 and 6 are related to the distance L from the photoelectric switch to the detected object 4 as shown in FIG. And Here, ( _{IPD1− IPD2} ) / _IPD1 is calculated from the outputs _IPD1 and _IPD2 of the light receiving elements 5 and 6, and the relationship with the distance L from the photoelectric switch to the detected object 4 is obtained. The relationship is as shown in 2 (b). The distance L to the detected object 4 is obtained from the relationship shown in FIG. 2B, and the distance L to the detected object 4 is obtained by correcting the relationship between the distance L and the light receiving element output shown in FIG. On the other hand, a flat received light output can be obtained. The relationship shown in FIG. 2B does not depend on the reflectance of the object. Therefore, it is possible to detect an object that does not depend on the distance to the object or the reflectance of the object.

In the above embodiment, the light projection / light reception coaxial type optical system has been described, but the distance detection independent of the object reflectance is possible even if the optical system is not the coaxial type. Further, if the reflectance of the object does not change, it is possible to perform detection regardless of the distance to the object, only by calculating the outputs of the two light-receiving elements ( _{IPD1- IPD2} ).

As described above, according to the present invention, the outputs of the light receiving elements arranged on the light receiving axis and at the positions deviated from the light receiving axis are calculated, and the distance detection independent of the reflectance of the object is realized. As a result, the received light output is corrected based on the measured distance value. As a result, it is possible to realize a stable, highly reliable and highly reliable photoelectric switch that does not depend on the distance to the object or the object reflectance.

[0011]

[Effect of device]

 As described above in detail with reference to the embodiments, according to the present invention, it is possible to realize a highly reliable reflection type photoelectric switch with stable operation and high reliability.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a reflective photoelectric switch of the present invention.

[FIG. 2] Distance and output of light receiving element and distance (I _PD1 −I
It is a figure which shows the relationship of _PD2 ) / _IPD1 .

FIG. 3 is a conventional example of a reflective photoelectric switch.

FIG. 4 is a diagram showing a relationship between distance and received light amount.

[Explanation of symbols]

 1 Light emitting element 4 Detected object 5 Light receiving element placed on the optical axis 6 Light receiving element placed off the optical axis

Claims (1)

[Scope of utility model registration request] 1. A reflective photoelectric sensor for detecting the presence or absence of the detected object by irradiating the detected object with light emitted from a light projecting element and receiving light reflected by the detected object by a light receiving element. In the switch, the light-receiving element is arranged on the light-receiving axis and at a position displaced from the light-receiving axis, and the object to be detected is detected from detection signals from the plurality of light-receiving elements. Photoelectric switch.