JPH0627866B2 - Heat ray type human body detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat ray type human body detector that detects a heat ray emitted from a human body by a pair of heat ray detecting elements known as twin elements and gives an alarm.

[Prior Art] Conventionally, in a heat ray type human body detector using a so-called twin element provided with a pair of heat ray detecting elements, as shown in FIG. B exists,
The heat rays when a person passes through the caution areas A and B are collected by the Fresnel lens of the detector 1 and incident on the twin element provided inside, and the passage of a person is detected based on the detection output of the twin element. is doing.

FIG. 4 shows a circuit configuration of a conventional heat ray type human body detector using a twin element.

In FIG. 4, reference numeral 10 denotes a detection unit having twin elements, 1
Reference numeral 2 is an amplifier circuit, 14 is an absolute value circuit, 16 is a comparator, 18 is a timer circuit, and 20 is an alarm circuit.

The operation of such a conventional circuit will be described below with reference to the signal waveform diagram of FIG.

First of all, the detection unit 10 includes the two warning areas A shown in FIG.
When a person passes through the warning areas A and B having B, a detection output a having positive, negative and positive amplitude polarities continuously changing as shown in FIG. That is, the detection output is an output obtained by temporally combining the outputs of the two heat ray detecting elements. Detector 1
The detection output a of 0 is amplified by the amplifier circuit 12, and then converted by the absolute value circuit 14 into an absolute value output b which is only a positive amplitude change, as shown in FIG. Absolute value circuit 1
The output b of 4 is input to the comparator 16 and is compared with the threshold level V _r shown by the broken line in FIG. 5 (b), and when it exceeds the threshold level V _r , it rises to the H level and becomes a constant pulse width. The comparator output c shown in FIG. 5C is generated. That is, the comparator 16 outputs a pulse train consisting of three consecutive pulses c1, c2, c3 as shown in the figure when a person passes by.

The timer circuit 18 measures the constant time T1 from the rising of the first pulse c1 output from the comparator 16
Timer and a certain time T2 from the time when the certain time T1 has elapsed
A second timer for setting the frame time of is provided, and a timer output is generated only when the second pulse c2 is obtained within the frame time T2 after T1 time has elapsed from the first pulse c1. By this, the alarm circuit 20 is activated to issue an alarm.

Here, the T1 time of the timer circuit 18 is the warning area A,
It is determined based on the shortest passage time of a person with respect to B, and even if the pulse C2 is detected in a shorter time than this, it is ignored as noise to prevent false alarm. Also, T2 time is in warning area A,
It is set based on the longest time required for a person to pass through B, and even if the pulse C2 is detected for a longer time, it is ignored as noise (low frequency noise) to prevent false alarms. In other words, T1 time should be set to prevent false alarms for high-frequency noise that occurs continuously in a short time, while T2 time should be set to prevent false alarms for low-frequency noise such as atmospheric fluctuations. I have to.

[Problems to be Solved by the Invention] However, in such a conventional heat ray type human body detector using a twin element, as shown in FIG. The amplitude change of the negative polarity that occurs at 1 is a gradual change with respect to the amplitude change of the positive polarity before and after, and therefore, the second pulse of the comparator is determined by the method of determining the threshold level V _r shown in FIG. The output timing of c2 changes greatly, and the threshold level V is set so that the timing of the timer circuit 18 exceeds T1 time.
There was a problem that the adjustment work for determining _r becomes complicated.

In addition, the frequency of the twin element output can be correctly detected by capturing the amplitude peak, but in the past, it was determined by measuring that the frequency exceeded the threshold level,
There was a problem that the frequency could not be detected accurately.

The present invention has been made in view of such a conventional problem, and has a highly reliable hot-wire human body configured to accurately detect a frequency change from a detection output of a twin element and prevent false alarms and false alarms. The purpose is to provide a detector.

[Means for Solving the Problem] In order to achieve this object, in the heat ray type human body detector of the present invention, the heat ray emitted from the human body passing through the predetermined warning area is detected, and the amplitude polarity is temporally changed. A detection unit including a pair of heat ray detection elements that generate a detection output that changes positively, negatively, and positively or vice versa; an amplification circuit that amplifies the output of the detection unit; and an output of the amplification circuit An absolute value circuit for converting into an absolute value signal having only the amplitude change of the polarity of; a clip circuit for extracting a signal waveform exceeding a predetermined level from the output of the absolute value circuit; a peak for detecting a peak of the output signal of the clip circuit A detection circuit; and a timer circuit which outputs only when a next peak detection signal is obtained within a predetermined time T2 after a lapse of a predetermined fixed time T1 from the time when the first peak detection signal is obtained from the peak detection circuit And an alarm circuit which is activated by the output of the timer circuit and issues an alarm.

[Operation] According to the heat ray type human body detector of the present invention having such a configuration, since the peak of the twin element detection output is detected, the frequency can be accurately discriminated, and noise and passage of the human body can be detected. Accurate identification is performed, and even if the detection frequency is close to noise, no false alarm or false alarm occurs, and high reliability is obtained.

[Embodiment] FIG. 1 is a configuration diagram of an embodiment showing one embodiment of the present invention.

In FIG. 1, 10 is a detection unit using a twin element, which has two warning areas A and B as shown in FIG. 3, and heat rays emitted from a human body passing through the two warning areas A and B. To detect. Reference numeral 12 is an amplifier circuit that amplifies the detection output of the detection unit 10, and 14 is an absolute value circuit that converts the output of the amplifier circuit 12 into an absolute value signal that is only a positive polarity amplitude change.

A clip circuit 22 and a peak detection circuit 24 are provided following the absolute value circuit 14.

The clip circuit 22 sets a constant clip level Vc for the output signal of the absolute value circuit 14,
Only signal waveforms that exceed

That is, in the clip circuit 22, the clip level Vc created by the series circuit of the resistor R1, the variable resistor VR and the resistor R2 is set on the non-inverting input side of the operational amplifier 28, and the output of the operational amplifier 28 is provided on the inverting input side of the operational amplifier 28. Will be returned. The output signal from the diode D1 is additionally connected to the cathode side of the diode D2 provided at the output of the operational amplifier 28.

In the operation of the clip circuit 22, the diode D1 is turned off and the output of the operational amplifier 28 is at the clip level when the input signal from the absolute value circuit 14 is below the clip level Vc. When the output signal from the absolute value circuit 14 exceeds the clip level Vc, the diode D1 is turned on and the signal is sent to the peak detection circuit 24.

By providing such a clipping circuit 22, it is possible to remove noise components below the clipping level Vc.

Following the clip circuit 22, a peak detection circuit 24 is provided. The peak detection circuit 24 detects the peak value of the clip output of the clip circuit 22. That is, the peak detection circuit 24 has a comparator 30, the output of the clip circuit 22 is connected to the non-inverting input of the comparator 30, and the inverting input functions as a voltage source in which a resistor R4 and a capacitor C1 are connected in parallel. Is connected to the tank circuit. This resistance R
In the tank circuit in which 4 and the capacitor C1 are connected in parallel, the output of the clip circuit 22 is given via the resistor R3. Further, the tank circuit in which the resistor R4 and the capacitor C1 are connected in parallel is connected to the output of the comparator 30 through the series circuit of the diode D3 and the resistor R5, and the diode D3 and the resistor R5 form a discharging circuit of the capacitor C1. ing. Further, the output of the comparator 30 is pulled up to the power supply voltage by the resistor R6.

The peak detection circuit 24 directly inputs the output signal from the clipping circuit 22 to the non-inverting input terminal of the comparator 30, and slightly delays the inverting input terminal by a tank circuit in which a resistor R4 and a capacitor C1 are connected in parallel. The detected signal is input, and the output of the comparator 30 is inverted at the signal cross between the non-inverted input and the inverted input at the peak timing of the input signal to detect the peak. That is, the signal level of the inverting input reaches the peak with a certain delay time after the input signal to the non-inverting input of the comparator 30 reaches the peak. At this time, since the non-inverting input side has passed the peak, the signal becomes the non-inverting input. On the other hand, the inverting input becomes larger, and at this time, the output of the comparator 30 is inverted from the H level to the L level. When the output of the comparator 30 is inverted to the L level, the charge stored in the capacitor C1 is rapidly discharged through the diode D3 and the resistor R5, and the inverting input is forcibly lowered so that the output of the comparator 30 returns to the H level again. Like
The resistor R4 and the capacitor C1 also have a function as a noise filter. That is, the relationship between the non-inverting input and the inverting input depends on the time constant of the capacitor C1 and the resistor R4, and the inverting input follows the non-inverting input of the comparator 30 for low frequencies such as fluctuations exceeding the clip level. It does not detect peaks and has a high-pass filter function.

The output of the peak detection circuit 24 is input to the timer circuit 26. The timer circuit 26 is provided with two timers 32 and 34 and a delay circuit 36. The timers 32 and 34 operate according to the peak detection signal from the peak detection circuit 24, and generate timer outputs for a fixed time.

More specifically, the timer 32 is activated by the first peak signal from the peak detection circuit 24 and produces a timer output over a detection window time T2 which determines the frequency range corresponding to the passage of the human body. The timer output of the timer 32 is delayed by the delay circuit 36, and the delay time of the delay circuit 36 is the non-detection time T1 until the start time of the detection window time T2 set after the first peak detection signal is obtained from the peak detection circuit 24. Is set as the delay time.

When the timer 34 receives the first peak detection signal from the peak detection circuit 24, the output of the delay circuit 36 is at L level, and the delayed output of the delay circuit 36 is given to the reset terminal of the timer 34. The timer 34 is reset in the initial state and does not operate even when receiving the first peak detection signal. The timer 34 is released from the reset state when a delay output of H level is obtained from the delay circuit 36 based on the first peak detection signal, and then the peak detection signal (second) output from the peak detection circuit 24. And outputs a timer output having a predetermined time width to the alarm circuit 20. The time of the timer output generated by the timer 34 has only to be a time width sufficient for operating the alarm buzzer and the indicator lamp provided in the alarm circuit 20, and is unrelated to the detection frequency range of human body passage and the noise frequency. .

Next, the operation of the embodiment of FIG. 1 will be described with reference to the signal waveform diagram of FIG. 2A.

The detection unit 10 has two warning areas A and B shown in FIG. 3, and when a person passes through the warning areas A and B, the detection output a shown in FIG. That is, the detection output A is an output in which the amplitude polarity continuously changes to positive, negative, and positive in response to the passage of a person. The detection output a of the detection unit 10 is amplified by the amplification circuit 12, and then converted by the absolute value circuit 14 so as to have all positive amplitude components, and becomes the absolute value signal b shown in FIG. 2A (b). Absolute value output b from absolute value circuit 14
Is input to the clipping circuit 22, and only the amplitude component above the clip level Vc shown by the broken line in FIG. 2A (b) is extracted, and the noise level below the clip level Vc is cut. The clip output of the clip circuit 22 is input to the peak detection circuit 24. As shown in FIG. 2B, the operation of the peak detection circuit 24 is such that the signal d shown by the solid line is input to the non-inverting input of the comparator 30, while the signal having a slight tracking delay shown by the broken line to the inverting input. e inputs. Therefore, when the signal d reaches the peak and then slightly lowers, the signal e reaches the peak with a delay, so that the signal d which was larger than e becomes larger than the signal e, and therefore the signal e becomes larger than d. The output of is inverted from H level to L level at this point. When the output of the comparator 30 is inverted to the L level, a discharge circuit is formed for the capacitor C1 via the diode D3 and the resistor R5, and the capacitor C1 is formed.
The rapid discharge of 1 causes the signal e to drop sharply, and when the signal d falls below the signal d again, the output of the comparator 30 returns to the H level. As a result, the peak detection circuit 24 generates the peak detection signal, that is, the peak detection pulse c at a timing very slightly delayed from the peak of the clip signal from the clipping circuit 22.

By such peak detection by the peak detection circuit 24, the peak detection circuit 24 outputs the peak detection signal shown in FIG. 2A (c), that is, three peak detection pulses c1, c2, c3 synchronized with the peak timing of the clip output. To do.

The timer circuit 26 is triggered by the first peak detection pulse c1 and produces a timer output for the detection window time T2. The first peak detection pulse c1 is also input to the timer 34,
At this time, since the reset signal to the timer 34 by the delay circuit 36 is at the L level, the timer 34 is not placed in the reset state and is not triggered by the first peak detection pulse c1.

The timer output of the timer 32 is delayed by the delay circuit 36 for T1 time. Therefore, when the delay time T1 elapses after the first peak detection pulse c1 is obtained, the output of the delay circuit 36 becomes H.
The level becomes level and the reset state of the timer 34 is released.

Delay time T1 after the first peak detection pulse c1 is obtained
If the second peak detection pulse c2 is output while the reset state of the timer 34 after the lapse is released, the timer 34 is triggered by the peak detection pulse c2, and the timer 34 warns the timer output of the predetermined time width. The signal is output to the circuit 20, and the alarm circuit 20 performs an alarm operation by turning on an alarm indicator lamp, ringing a buzzer, or the like.

Of course, the timer 32 which is first triggered stops the timer output when the set time T2 elapses, and the output of the delay circuit 36 also becomes the L level after the delay time T1 after the timer output of the timer 32 is stopped and the timer 34 is restarted. Reset.

As described above, according to the present invention, the peak timing of the detection output of the detection unit 10 using the twin element is accurately detected, and the human body is detected by comparison with the preset detection frequency range, specifically, the timer setting time. It is possible to accurately detect the detection frequency due to the passage of the human body with respect to popcorn noise, noise with a high frequency, and low frequency noise due to atmospheric fluctuations, etc., and it is possible to reliably prevent false alarms and false alarms.

In the above embodiment, the timer 32 and the delay circuit 36
With, the T1 time for ignoring the peak detection pulse as noise and the frame time T2 for discriminating the peak detection pulse due to passage of the human body after T1 time have been set. However, the first timer prohibits detection at the first T1 time. The
The second timer may be started after the time T1 to set the detectable time.

As described above, according to the present invention, since the peak of the detection output of the twin element is detected, the frequency fluctuation of the detection output due to the passage of a person to the two warning areas based on the twin element is accurately detected. Therefore, the noise and the passage of the human body can be accurately identified, and high reliability can be obtained without causing false alarm.

[Brief description of drawings]

1 is a block diagram of an embodiment of the present invention; FIG. 2A is a signal waveform diagram showing the operation of FIG. 1; FIG. 2B is a signal waveform showing the operation of a comparator provided in the peak detection circuit of FIG. FIG. 3 is an explanatory diagram of a monitoring area of a twin element; FIG. 4 is a configuration diagram of a conventional device; FIG. 5 is a signal waveform diagram showing an operation of the conventional device. 10: Detection unit (twin element) 12: Amplification circuit 14: Absolute value circuit 20: Alarm circuit 22: Clip circuit 24: Peak detection circuit 26: Timer circuit 28: Operational amplifier 30: Comparator 32, 34: Timer 36: Delay circuit

Claims (1)

[Claims] 1. A pair of heat wires that detect heat rays emitted from a human body passing through a predetermined monitoring area and output detection signals whose amplitude polarities continuously change from positive polarity to negative polarity and vice versa, or vice versa. A detection unit having a detection element; an amplification circuit for amplifying the output of the detection unit; an absolute value circuit for converting the output of the amplification circuit into an absolute value signal which is an amplitude change of only one polarity; and the absolute value. A clip circuit that extracts a signal waveform exceeding a predetermined level from the output of the circuit; a peak detection circuit that detects a peak of the output signal of the clip circuit; a predetermined from the time when the first peak detection signal is obtained from the peak detection circuit And a timer circuit that outputs only when the next peak detection signal is obtained within a predetermined time after the elapse of a certain time; and an alarm circuit that issues an alarm by the output of the timer circuit; Human body detector.