JPH0381686A - Reflection type human body detecting circuit - Google Patents

Abstract

PURPOSE:To eliminate malfunction due to a fast body and a disturbing light noise by reflecting a light emission pulse by a human body and receiving it by a photodetecting circuit, converting the pulse into a DC voltage by the DC voltage converting circuit consisting of an integration circuit and a comparing circuit, and regarding the current constant of smoothing as a speed matching the human body speed. CONSTITUTION:When the light pulse is reflected by the human body, the pulse with wide pulse width is obtained from the photodetecting circuit 3 and an output with narrow pulse width is obtained with a reflected pulse from a body which moves faster than the human body. Therefore, when the reflected light from the human body is made incident, the output of the integration circuit 41 exceeds a threshold value, but when the reflected light from the fast body is made incident, the output of the circuit 41 does not exceed the threshold value. Here, the time constant of the circuit 41 is set to, for example, 200 - 500ms and a comparing circuit 42 does not decide that there is human body in response to a body which is faster than the set value and disturbing light. The presence of a human body is detected for a body which is slower than the set value or the human body.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a reflective human body detection circuit, and is particularly suitable for preventing an object moving faster than a human body from being mistakenly detected as a human body. Related to human body detection circuit.

[Conventional technology]

Conventional human body detection circuits are not limited to human body detection; in order to provide versatility, they are configured to be able to detect objects that move faster than the human body. In addition, as related to the above-mentioned prior art, Japanese Patent Application Laid-Open No. 157-1983
There is an invention disclosed in Publication No. 297.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into consideration the fact that only human bodies are detected, and there is a problem in that even high-speed objects are detected.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reflective human body detection circuit that can detect only a human body and an object that moves at a similar speed to the human body, without detecting high-speed objects.

[Means to solve the problem]

The reflective human body detection circuit of the present invention includes a light emitting circuit for lighting a light emitting diode in pulses, a light receiving circuit for receiving one reflected light pulse, an integrating circuit for smoothing the output of the light receiving circuit, and a predetermined output from the integrating circuit. In a reflection-type human body detection circuit consisting of a comparison circuit that determines the presence or absence of a human body by comparing it with a threshold value determined by The feature is that the value is set to .

[Effect]

In the reflective human body detection circuit of the present invention, a light emitting pulse is reflected by the human body, this light is received and received by a light receiving circuit, and a DC voltage conversion circuit consisting of an integrating circuit and a comparison circuit converts the output of the light receiving circuit from a pulse to a DC voltage. Convert. At this time, the smoothing time constant is set at a speed commensurate with the human body speed (for example, 200 m s
~500 m s) to prevent malfunctions caused by high-speed objects or disturbance light noise.

〔Example〕

The present invention will be described in more detail below with reference to embodiments shown in the accompanying drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. As shown in FIG. 1, one light emitting diode 2 outputs a light pulse based on the output of the oscillation circuit 1.

The light pulses output from the light emitting diode 2 are reflected by the human body or other objects and enter the light receiving circuit 3. The light receiving circuit 3 outputs the light receiving output to the DC voltage conversion circuit 4. The DC voltage conversion circuit 4 includes an integrating circuit 41 and a comparing circuit 42.
The integrating circuit 41 integrates the light receiving output from the light receiving circuit 3 with a predetermined time constant, and outputs the value to the comparing circuit 42.

The comparison circuit 42 compares the input integral value with a predetermined threshold value, and determines H (human body detection) only when the threshold value is exceeded.

FIG. 2 is a waveform diagram showing an example of the operation of the embodiment shown in FIG. As shown by the solid line in FIG. 2, when a light pulse is reflected by the human body, a pulse with a wide pulse width is obtained from the light receiving circuit 3. Further, when a light pulse is reflected by an object moving faster than a human body, an output with a narrow pulse width is obtained from the light receiving circuit 3 as shown by the dotted line. Therefore, when the reflected light from the human body is incident,
The output of the integrating circuit 41 exceeds the threshold value, but when reflected light from an object moving faster than the human body enters,
The output of the integrating circuit 41 does not exceed the threshold. Here, the time constant of the integrating circuit 41 is, for example, 200 m5 to 500 m5.
It is set between ms and s.

When the object is faster than this set value and the disturbance light noise is present, it is not determined that a human body is present. Further, in the case of an object or a human body that moves slower than the set value, it is detected that a human body is present.

According to this embodiment, human bodies and low-velocity objects similar to human bodies can be detected reliably, and there is no malfunction in the case of objects with higher velocity than the time constant setting value or ambient light noise, and the presence of human bodies can be accurately detected. effective.

The reflective human body detection circuit of the present invention can be widely used as a trigger signal for ATM (Full Automatic Transaction Machine) guidance or as a trigger signal for toilet flushing.

〔Effect of the invention〕

According to the present invention, objects and human bodies that are slower than the time constant set between 200 m5 and 500 m s can be reliably detected, and in the case of objects that are faster than that or disturbance light noise, It is never determined that a human body has been detected. Therefore, there is an effect that the human body can be detected reliably.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a waveform diagram for explaining the operation of the embodiment shown in FIG. 1...Oscillation circuit. 2... Light emitting diode. 3... Light receiving circuit 4... DC voltage conversion circuit. 41... Integral circuit. 42... Comparison circuit.

Claims (1)

[Claims] 1. A light emitting circuit that pulses the light emitting diode, a light receiving circuit that receives reflected light pulses, an integrating circuit that smoothes the output of the light receiving circuit, and a comparison between the output of the integrating circuit and a predetermined threshold value. A reflective human body detection circuit comprising a comparison circuit for determining the presence or absence of a human body, characterized in that the time constant when the integrating circuit smoothes the output of the light receiving circuit is set to a value corresponding to the moving speed of the human body. Reflective human body detection circuit.