JPH05213485A - Object detection device - Google Patents

Abstract

PURPOSE:To provide an object detection device on a conveyor for conveying objects such as paper, capable of regulating the output of a sensor portion at checking prior to operation even if the output is lowered. CONSTITUTION:A common threshold-level setting portion 4 is provided which can vary a threshold level to be compared with the output of a sensor portion 2 which receives the light of the LED of a light emitting portion 1. The output of the threshold-level setting portion 4 is regulated during checking prior to operation, so that detection is made possible without mistakes even if the output of the sensor portion 2 is lowered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object detecting device, and more particularly to an object detecting device for detecting the presence / absence of an object on a conveying device for conveying an object such as paper, depending on whether or not the object is in an optical path.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, an object detecting apparatus of this type includes a light emitting section 1 capable of turning on and off an LED,
Sensor unit 2 that outputs a signal according to the amount of light received from the LED
And a comparison unit 3 which compares the output of the sensor unit 2 with a fixed threshold level and outputs a logical value signal of "1" or "0".

With the above arrangement, the output of the comparison section 3 is checked while the LED is emitting light before the object detection. If the LED emits light normally and the sensor unit 2 also outputs a signal according to the amount of received light, the output of the sensor unit 2 exceeds the threshold level in the comparison unit 3, so the output of the comparison unit 3 becomes "0". , "No object" state. However, when there is a disconnection in the light emitting unit 1 or the sensor unit 2 and the output of the sensor unit 2 is lost, or paper dust or dust that accompanies the transportation of the object is accumulated between the light emitting unit 1 and the sensor unit 3, etc. By this, when the output of the sensor unit 3 decreases and becomes lower than the threshold level, the output of the comparison unit 3 becomes "1", indicating the "object present" state, and the abnormality of the object detection device can be known. Next, the output of the comparison unit 3 is checked with the LED turned off. When the LED is normally extinguished, the output of the sensor unit 2 disappears, so the output of the comparison unit 3 becomes "1", indicating the "object present" state. However, if the output of the sensor unit 2 exceeds the threshold level due to some failure of the light emitting unit 1 or the sensor unit 2, the output of the comparison unit 3 is "0".
Then, the "no object" state is shown, and the abnormality of the object detection device can be known.

[0004]

In the above-mentioned conventional object detecting device, since the threshold level is fixed, the LED is in the light emitting state and the output of the comparing section is "1",
That is, when the state of "object present" is shown, there is a drawback that the object detection device cannot be used as a failure unless something is repaired because the light emitting part or the sensor part is abnormal regardless of the cause. is there.

It is an object of the present invention to provide an object detecting device which can be used in a wide range by checking before the operation even if the output of the sensor unit is lowered.

[0006]

SUMMARY OF THE INVENTION An object detecting device of the present invention is an object detecting device that detects the presence or absence of an object on a conveying device that conveys an object, such as paper, by checking whether the object is in the optical path. .LE capable of controlling lights out
A light emitting part having D, a sensor part for outputting an electric signal according to the amount of light received from the LED of the light emitting part, and a threshold level generating part which can be arbitrarily set in output level and is provided commonly to a plurality of object detection devices. And a comparator which compares the magnitude of the output from the threshold level generator with the electrical signal output from the sensor to output a signal of logical value "1" or "0". .

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention.
The embodiment shown in FIG. 1 comprises a light emitting section 1, a sensor section 2, a comparing section 3, and a threshold level setting section 4. The light emitting unit 1 is composed of an LED and a power source for controlling lighting and extinguishing of the LED. The sensor unit 2 receives the light from the LED and outputs an output signal according to the amount of received light. The comparison unit 3 compares the output signal from the sensor unit 2 and the output from the threshold level setting unit 4 and outputs a logical value “0” when the output signal is large and a logical value when the output signal is small. Value "1"
Is output. The threshold level setting unit 4 is a common power supply capable of arbitrarily changing the threshold levels of the plurality of object detecting devices to the comparing unit 3, and is commonly provided for the plurality of object detecting devices.

Next, a description will be given of a check before operation when a plurality of object detection devices having the above-described configuration are provided in the transport device. First, while the LED is emitting light, the upper limit value that can set the threshold level is set first, and all the object detection devices are in the "no object" state, that is, the comparison unit 3
Check if the output of "0" is "0", and if "no object", 1/2 of the threshold level at that time.
Is the threshold level for object detection.
If there is at least one detector with "object" in the setting of the upper limit value, the threshold level is lowered and a check is performed, and all detectors are lowered until "no object". However, the threshold level when all the detection devices are in the "no object" state is the limit value, that is, the output of the LED is transmitted through the object though the detection device actually has an object due to the variation in sensitivity. If the output of the sensor unit 2 becomes high and the output of the comparison unit 3 becomes "no object", it is determined that the sensor unit 2 of the corresponding detection device is defective, and the device is It is considered a failure. When the threshold level does not fall below the limit value, 1/2 of the threshold level at that time is set as the threshold level at the time of object detection. Next, after setting the threshold level for object detection, turn off the light emitting part,
Check if the state of all detectors is "object present". If all the sensors have "objects", it is normal, but if there is even one "no object" detection device, it is regarded as abnormal and the detection device fails.

[0010]

As described above, according to the present invention, the threshold level of the comparison section can be set to an arbitrary value, so that the paper dust and dust of paper sheets are accumulated and the output of the sensor section is lowered. However, it is possible to lower the threshold level, which is not the same as the threshold level, and it is possible to prolong the operation time without bringing the device into a failure state. In addition, the output level of each sensor can be considered to be almost the same as the threshold level when the state changes from "with object" to "without object", so sensor output without using a tester or other measurement device. The level can be known, and by knowing the output level of the sensor, it is possible to recognize that the paper dust and dust of the sensor unit and the LED unit can be removed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional object detection device.

[Explanation of symbols]

 1 Light emission part 2 Sensor part 3 Comparison part 4 Threshold level setting part

Claims (1)

[Claims] 1. An object detection device for detecting the presence / absence of an object on a transfer device for transferring an object such as paper, according to whether or not the object is in an optical path. A light emitting section having, a sensor section for outputting an electric signal according to the amount of light received from the LED of the light emitting section, an output level can be arbitrarily set, and a threshold level generating section commonly provided for a plurality of object detection devices, Object detection, comprising: a comparison unit that compares the magnitude of the output from the threshold level generation unit with the electric signal output from the sensor unit and outputs a signal of logical value "1" or "0". apparatus.