JPS61219886A - Transmission type photoelectric sensor having plural detection levels - Google Patents

Abstract

PURPOSE:To detect the weakening of the light arrival force by judging the quantity of received light on a plurality of detection levels and binarizing the judged result to output the same as external output corresponding to that detection level. CONSTITUTION:The optical signal 11 from a light emitting part 1 transmitted through an article to be detected is received by a light receiving part 2 to be converted to an electric signal 12 which is, in turn, amplified by an amplifier 3. This amplified signal 13 is compared with detection levels (a)-(d) by a level (a) discrimination part 4a, a level (b) discrimination part 4b, a level (c) discrimi nation part 4c and a level (d) discrimination part 4d and, as a result, electric signals 14a-14d are obtained to be outputted as external outputs 15a-15d through output circuits 5a-5d.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transmission type photoelectric sensor that detects the presence or absence of an object using light.

[Technological environment]

In recent years, mechanical devices have become more labor-saving and more diverse, and their control has also become more demanding. M and increasing in scale. Under such circumstances, there is a strong desire throughout the industry to improve the reliability and increase the functionality of sensors, which are the key to control.

There are many types of sensors of this type, but among them, photoelectric sensors, which detect the presence or absence of foreign objects, are essential sensors for the operation of mechanical equipment due to their high reliability and applicability. There is one.

[Common technology]

Generally, in a transmission type photoelectric sensor, a light receiving part is placed opposite a light projecting part that emits light, with an appropriate distance therebetween.

Set up so that the light from the light emitter hits the surface of the light receiver. Therefore, 1. Normally, the surface of the light receiving section will continue to receive the light from the light emitting section, but if there is an object blocking the light between the light projecting section and the light receiving section, the surface of the light receiving section will continue to receive the light from the light emitting section. Light will no longer reach you.

The presence or absence of an object is detected by changes in the amount of light reaching the light receiving section from the light projecting section.

[Prior art]

As shown in the block diagram of FIG. 2, the conventional transmission type electric sensor includes a light projecting section l that emits an optical signal 11, a light receiving section 2 that converts the received optical signal 11t into an electrical signal 12, and an electrical signal. 12 into an electrical signal 13 and an amplifying section 3, which converts the electrical signal 13 into an electrical signal 13.
a level discriminator 4 which compares ' with a detection level, binarizes the result and outputs it as an electrical signal 14;
It is composed of an output circuit 5 that outputs an output to the outside as an external output 15.

[Problem that the invention seeks to solve]

The conventional transmission type photoelectric sensor mentioned above has a detection level of 1
Because only one light beam exists, the light reaching power may be affected by the surface of the light emitting part or light receiving part being dirty or due to adhesion of foreign substances such as water droplets, or due to deterioration of the optical axis between the light emitting part and the light receiving part, etc. Even when it has weakened, it is difficult to detect it, which is one of the causes of detection malfunctions.

Additionally, if the transparency, shape, and size of each object to be detected differed, it was necessary to adjust the sensitivity of the amplification section in advance to achieve the optimal detection level for detecting the object. .

Therefore, in the case of a device with a high detection sensitivity (in the case of a device in which two or more different types of targets are sent in succession, it is necessary to arrange two or more sensors).

[Means to solve the problem]

It is an object of the present invention to eliminate the above-mentioned drawbacks, and to prevent the sensor from reaching the area where the light reaching power is weakened due to other reasons even though there is no cutter blocking the light between the light emitting part and the light receiving part. Deterioration can be amortized externally, and for other applications, it is possible to detect two or more pairs with different detection sensitivities without adjusting the sensitivity in the middle.
The object of the present invention is to provide a transmission type electric sensor named U.

According to the present invention, there is provided a light projecting section that projects light, a light receiving section that converts the received light into an electrical signal, an amplifying section that amplifies the signal photoelectrically converted in the light receiving section, and a signal amplified by the amplifying section. Judge signals at multiple detection levels.

It includes a level discrimination unit that binarizes and outputs the result to an output circuit corresponding to the detection level, and an output circuit that outputs to the outside a binarized signal corresponding to each detection level from the level half division unit. A transmission-type power sensor that uses this as a percentage can be obtained.

〔Example〕

Next, two embodiments of the present invention will be described in detail with reference to one drawing.

FIG. 1 is a configuration block diagram showing an embodiment of the present invention.
A light projecting section l that emits an optical signal 11, a light receiving section 12 that converts the received optical signal 11 into an electrical signal 12, an amplifying section 3 that amplifies the electrical signal 12 into an electrical signal 13, and an amplifying section 3 that converts the optical signal 11 into an electrical signal 13; Compare a to d and binarize the results to generate electrical signal 1
A level a discrimination section, a level b discrimination section, a level C discrimination section, and a L/ /</L/ d discrimination section, which are outputted as 42 to 14d to each output circuit 53 to 5d, and the mki 1d 14a-
14d and t-output circuits 5a to 5d that output as external outputs 158 to 15d, respectively.

Now, enter the level determination section! The logic is set so that when the fi signal is above the detection level, the external output is ft0N, and when it is below the detection level, the external output is OFF.Detection level a is the highest signal level, and below the detection level If the signal level is low in the order of b, c, and d, and there is no object blocking the light between the emitter and receiver, the external outputs 15a to 15d are all output between the ONL emitter and receiver. When light is blocked, external output 15a-=
Set so that all d are turned off.

For example, there are detectable objects C and D with different detection sensitivities, and detectable object C has a detection sensitivity that exceeds detection level d but does not exceed detection level C, and detectable object has a detection sensitivity that does not exceed detection level d. If you think about it.

Objects C and D can be detected by monitoring external outputs 15c and 15d corresponding to detection levels c and d.

In addition, when the external output 15a or 15b is OFF and the external output 15C or 15d is ON, the detected object C
Alternatively, it can be determined that the change in the amount of light received is due to a cause other than D. That is, it is possible to detect deterioration due to contamination or the like on the surface of the light projector or the light receiver, or a shift in the optical axis.

Therefore, the surface of the light emitting part 1 or the light receiving part 2 has deteriorated due to dirt or foreign matter such as water droplets.
Due to factors such as misalignment of the optical axis between the two.

If the light reaching power is weakened, it can be detected relatively early because the external output corresponding to the higher detection level is turned off even under the condition that there is no object blocking the light.

In addition, as another application, even if the optimal detection level differs between objects to be detected due to differences in transparency, shape, size, etc., it is possible to adjust the detection level corresponding to each object to be detected, so that the external By monitoring the ON/OFF status of the output.

A single sensor can detect multiple detection targets with different light detection sensitivities.

Note that here, the number of detection levels is four.

Needless to say, this number is variable.

〔Effect of the invention〕

As explained above, the transmission type photoelectric sensor of the present invention has the following features:
The amount of received light is judged at multiple detection levels, and the results are binarized and the corresponding detection level is determined. If the original axis between the light emitting part and the light receiving part is shifted, This has the effect that it is possible to detect even when the reaching power of light is weakened, and that a single sensor can detect a plurality of detection targets with different original detection sensitivities for <r applications.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a transmission type photoelectric sensor showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional transmission type photoelectric sensor. l...Light emitter, 2...Light receiver, 3...
...Amplification section, 4...Level discrimination fB, 4
a...Level a discrimination section, 4b...Level b 44JM section, 4c...Level C44J
Printing section, 4d...Level d discrimination section, 5...
・Output circuit, 5a... Output circuit, 5b...
...Output circuit, 5c...Output circuit, 5d...
...-output circuit, ii...original signal, 12...
...electrical signal, 13.old...electrical signal, 14.old...
Electrical signal, 14a... Electrical signal, 14b...
...Electric signal, 14C...Electric signal, 14d
...Electrical signal, 15...External output, 1
5a...External output, 15b...External output, isc...External output, 15d...
External output.

Claims (1)

[Claims] A light emitting section that emits light, a light receiving section that converts the received light into an electrical signal, an amplifying section that amplifies the signal photoelectrically converted in the light receiving section, and a signal amplified by the amplifying section that is sent to multiple detection levels. a level discriminator that makes a binary judgment and outputs the result to an output circuit corresponding to the detection level, and an output circuit that outputs to the outside a binary signal corresponding to each detection level from the level discriminator. A transmission type photoelectric sensor comprising: