JPH0452696Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an integrating device used in a human body detection method for automatic doors.

Prior Art As shown in Japanese Patent Application No. 126348/1980, the present applicant has previously proposed that the background of infrared light emitted from a projector and the output of a light receiver that receives reflected light from a human body can be detected from the background. The applicant has filed an application for a human body detection method that calculates the difference between the amount of reflection from the human body and the amount of reflection from the human body, and outputs a human body detection signal when the difference in the amount of reflection continues for a predetermined period and exceeds a predetermined value.

This human body detection method has the advantage that it does not malfunction due to changes in background conditions or temporal changes in the luminous efficiency of the projector, does not malfunction due to snowfall or sunlight, and can detect a stationary human body.

To implement such a human body detection method, the output of the light receiver is integrated by a first integrating circuit with a small time constant, and the average value of the sum of the amount of reflection from the background and the increase in the amount of reflection from the human body is calculated. At the same time, the output of the light receiver is integrated by a second integrating circuit with a large time constant so that the average value of the amount of reflection from the background does not increase even if the amount of reflection from the human body is received. The human body detection signal is configured to be output when the difference between the outputs of the two integrating circuits is greater than a predetermined value for a predetermined period of time or more.

However, if the time constant of the second integration circuit is large, it will take time to reach the original integrated value when the power is turned on or when the amount of reflection from the background changes due to changing the direction of the emitter and receiver. Therefore, the integrating device equipped with the first and second integrating circuits of the previously filed human body detection method is constructed as shown in FIG. 5.

That is, the output of the photoreceiver a is inputted to a first integrating circuit c and a second integrating circuit d via a sample-and-hold circuit b, and the first integrating circuit c is composed of a resistor e and a capacitor f, and the second integrating circuit c is composed of a resistor e and a capacitor f. A circuit d is connected to a capacitor g with first, second, and third resistors h, i, and j in parallel, and a first switch k is connected to the first resistor h.
Assume that a second switch l is connected in series to the second resistor i, and the first switch k is turned on for a predetermined time when the power is turned on and when a push button switch (not shown) is pressed. , the second switch l is set to turn off when a human body enters the detection area.

By doing this, under normal conditions when the power is turned on and the push button switch is OFF, and the human body is not in the detection range, the first switch k is
OFF, the second switch l is turned ON, and the time constant of the second integrating circuit d becomes an intermediate value _T2 corresponding to the combined resistance value of the second and third resistors i and j, and the amount of reflection from the background is determined. In addition to being able to integrate in the state of Value T ₁ (T ₂
> T ₁ ), the original integral value can be obtained in a short time, and when a human body enters the detection area under normal conditions, the second switch l is turned OFF, and a large value T ₃ corresponding to the resistance value of the third resistor j is obtained. (T ₃ > T ₂ > T ₁ ), and even if the amount of light reflected from the human body is received, the integral value does not increase much and a decrease in sensitivity can be prevented.

Problems to be Solved by the Invention With such an integrating device, the maximum value _T3 of the time constant of the second integrating circuit d becomes a value commensurate with the resistance value of the third resistor j, and the magnitude of the third resistor j Since there is a limit to the maximum value _T3 of the time constant, when the amount of reflection from the human body is input during normal times, the integral value of the second integration circuit d is determined by the increase in the amount of reflection. continues to rise little by little, and the sensitivity decreases.

In other words, if the human body continues to be in the detection area, the integral value of the second integrating circuit d increases sequentially, and the integral value of the first integrating circuit c
Since the difference between the integral value and the integral value becomes smaller, the sensitivity decreases.

Means and action for solving the problem A second integrating circuit connected to the output side of the photoreceiver is connected to a capacitor and a resistor when a human body enters the detection area.
As a structure connected via a switch that turns OFF,
When the human body enters the detection area under normal conditions, the time constant of the second integrating circuit becomes approximately infinite, so that even if the amount of reflection from the human body is input, the integrated value hardly increases.

Embodiment FIG. 4 is a schematic diagram showing how a light emitter and a light receiver are installed. A light emitter 2 and a light receiver 3 are disposed on a ceiling 1, and infrared light is directed from the floodlight 2 toward a floor 4 in an irradiation area 5. As shown in
The intersection of the light receiving area 6 and the irradiation area 5 is the detection area 7.

The projector 2 emits infrared light modulated at a predetermined frequency, and the receiver 3 receives the infrared light reflected from the background or the human body in the detection area 7, converts it into an electrical signal, and outputs it.

Figure 2 is a block diagram showing the human body detection method;
FIG. 3 is a table showing signal changes of each block. The emitter 2 emits infrared rays according to the emitter drive signal (pulse) _P1 from the emitter drive circuit 8, and the output of the receiver 3 is As shown in FIG. 3B, the output increases and decreases sequentially due to the intrusion of the human body, and the output is AC amplified by the amplifier 9 to reach the output level shown in FIG. , and held by the timing signal from the sample-and-hold timing signal generator 11.

The sample-and-hold timing signal generator 11 generates a projector drive signal as shown in FIG.
A timing signal (pulse) _P2 is output with a slight time delay from _P1 , and the sample-and-hold circuit 11 uses the output level of the amplifier 9 at the time when the above-mentioned timing signal _P2 is input as the next timing signal _P2 . It is held until the time when it is input, and its output is synchronized with the infrared light projection timing as shown in FIG. 3E.

In other words, the sample-and-hold timing signal generator 11 receives the projector drive signal P ₁ and generates a timing signal necessary for a sample-and-hold operation synchronized with the infrared emission timing of the projector 2.
Output P ₂ to the sample and hold circuit 10,
A sample-and-hold circuit 10 converts the output level of the light receiver 3 amplified by the amplifier 9 into a light emitter drive signal.
Hold and output every time P ₁ is output.

The output level of the sample and hold circuit 10 is integrated by first and second integration circuits 12 and 13.

The time constant (resistance value x capacitor capacity) of the first integrating circuit 12 is set small, and the temporal change in its output becomes very large, as shown in Figure 3, and the amount of reflection from the background and the human body is reduced. I try to capture both at the same time.

The second integrating circuit 13 has a time constant that is much larger than that of the first integrating circuit 12 and is set to approximately infinity, and the temporal change in its output is similar to that of the first integrating circuit 13 as shown in FIG.
It is much smaller than that of the integrating circuit, and even if the output level of the sample-and-hold circuit 10 suddenly increases, it does not reach that level immediately, and even if a human body enters the detection area 7, the output level does not reach that level. This means that the amount of reflection from the background can be captured by retaining almost the background level before the human body invades without increasing the amount of light.

The output levels of the first and second integrating circuits 12 and 13 are sent to a differential amplifier 14, which amplifies the difference a between the output levels shown in FIG. 3F to obtain the output level shown in FIG. 3H.

This makes it possible to extract the difference between the level of reflection from the background and the level of reflection from the human body when the human body enters the detection area 7, that is, the change in the output level of the light receiver 3, and amplify that change. Even when the background environment changes and the level of reflection from the background changes, only the amount of change in the output level of the light receiver 3 can be extracted and the amount of change can be amplified.

That is, since the amount of change mentioned above is very small, for example, about 0.01V, it is necessary to amplify it.

The output level of the differential amplifier 14 is determined by the comparator 15.
It is compared with the level setting value A of the level setter 16 as shown in FIG.
If this is the case, the comparator 15 outputs a signal _R1 at a predetermined voltage level, as shown in FIG.

This signal R ₁ is output to the pulse width discrimination circuit 17, and the pulse width discrimination circuit 17 observes the time during which the signal R ₁ is output, and detects that the signal R 1 has been output for a predetermined time t ₁ or more.
If R ₁ is output, the signal R ₂ remains at a predetermined voltage level until the signal R ₁ stops (until the output of the comparator 15 turns OFF) as shown in FIG.
Output.

Here, the predetermined time t ₁ during which the signal R ₁ is output
When reflected light from snow or sunlight enters the light receiver 3 directly or reflected, the light receiver 3 outputs it, and when the light receiver 3 receives and outputs reflected light from the human body. The time is long enough to distinguish between the two, and this prevents malfunctions caused by snow or sunlight.

In other words, the reflected light from the snow and the sun's rays are transmitted to the receiver 3.
Since the signal R 1 is input for a very short time, the time during which the signal R ₁ is outputted from the comparator 15 is shorter than the predetermined time, and the pulse width discrimination circuit 17
Do not output R ₂ .

The signal R ₂ from the pulse width discrimination circuit 17 is input to a timer 18, and the timer 18 starts operating the relay 19 when the signal R ₂ is input, and also starts operating the relay 19 after a predetermined time has elapsed since the signal R 2 is no longer input. The operation is stopped, and the relay 19 continues to output a human body detection signal to a controller (not shown) during operation.

In other words, as shown in Figure 3, the timer 18 operates the relay ₁₉ when the signal R2 is input from the pulse width discrimination circuit 17, and remains ON for the set time _t2 to operate the relay 19 even if the signal R2 is not input. Continue to do so.

As described above, the difference between the amount of reflection from the background and the amount of reflection from the human body, etc. is detected, and a human body detection signal is sent only when the difference in the amount of reflection is greater than a predetermined value and continues for a predetermined period of time. Therefore, if the duration of the difference in reflection amount is relatively short, such as when sunlight or reflected light from snow enters the light receiving unit, the human body detection signal will not be output, and the light emitting efficiency of the projector will change. If the difference in the amount of reflection is small, such as when there is a change in the amount of reflection from the floor surface, no human body detection signal is output, so no malfunction occurs.

It can also detect a stationary human body.

In addition, since the second integrating circuit 13 has a large time constant of approximately infinity in order to capture only the amount of reflection from the background, it has the following problem.

If the time constant is large, it will take too long to reach the original integral value when the power is turned on or when the amount of reflection from the background changes due to changing the direction of the emitter/receiver.

Therefore, as shown in FIG.
are connected in parallel, a first switch 24 is connected in series to the first resistor 21, a second switch 25 is connected in series to the second resistor 22, and the first switch 24
is connected to the push button switch 26 via the not gate 27, and connected to the power source via the timer 28,
The second switch 25 is connected to the output side of the pulse width discrimination circuit 17 via a not gate 29, and
The first switch 24 is activated by the time set by the timer 28 and the push button switch 26 when the power is turned on.
When the second switch 25 is turned on, it is turned on, and when the pulse width discrimination circuit 17 is outputting the signal R2, the second switch ₂₅ is turned off.

Because of this, under normal conditions when the power is continuously turned on and the push button switch 26 is OFF, no signal is input to the first switch 24, so it is OFF, and the pulse width discrimination circuit 17 does not output the signal _R2 , so the second switch is turned OFF. When a signal is input to 25, it turns ON.

Therefore, the second resistor 22 is connected to the capacitor 20.
is connected, and the time constant at this time becomes an intermediate value _T2 corresponding to the resistance value of the second resistor 22, which is a value sufficient to perform the above-mentioned integration operation.

In addition, when the power is turned on, the first switch 24 is turned on when the timer 28 is set and the push button switch 26 is turned on, so the first and second resistors 21 and 22 are connected in parallel to the capacitor 20, and the combined resistance value is as described above. The time constant at this time becomes the minimum value T ₁ (T ₂ >T ₁ ).

Therefore, when the power is turned on or when the push button switch 26 is turned on by changing the orientation of the emitter 2 and the receiver 3, the time constant of the second integrating circuit 13 can be made small and the original integral value can be obtained in a short time. .

In addition, in the above-mentioned normal state, when the human body enters the detection area and the pulse width discrimination circuit 17 outputs the signal _R2 , the second switch 25 is turned OFF, and the first and second resistors 21,
22 is not connected to the output side of the light receiver 3, and the capacitor 20 is connected to the first and second switches 24 and 25.
The leakage current when OFF starts to flow, and the resistance value at that time becomes almost infinite, so the time constant at that time is a nearly infinite value T ₃ regardless of the resistance values of the first and second resistors 21 and 22. becomes.

Therefore, when a human body enters the detection area, the second
The time constant of the integrating circuit 13 becomes almost infinite, so that if a human body continues to be in the detection area, the integral value will hardly increase and there will be almost no decrease in sensitivity. 17, the signal R ₂ is no longer output, and the second
Since the switch 25 is turned on, the time constant becomes small to _T2 , so the integral value returns to the original integral value in a short time.

Note that the first integrating circuit 12 includes a capacitor 23a and a resistor 23b, and its time constant T ₄ is small (T ₄ ≈T ₁ ).

The human body detection method described in the above embodiments has the following effects.

Since a human body detection signal is output based on the difference between the amount of reflection from the background and the amount of reflection from the human body, the human body can be accurately detected even if the luminous efficiency of the projector changes over time or the state of the background changes, preventing malfunctions. Not only is there no need to worry, it can also be detected even when the human body is stationary.

In other words, since the amount of reflected infrared light from the floor surface varies depending on temporal changes in the luminous efficiency of the floodlight and changes in the condition of the floor surface, the level of the amount of reflected infrared light is simply used to determine human body detection. When used, there is a slight temporal fluctuation in the reflection level itself due to the above-mentioned fluctuation in the reflection quantity, so it is necessary to prevent such fluctuations from being detected. It becomes difficult to detect the difference and the detection distance cannot be increased.

To solve this problem, it would be better to use a differential operation type that captures not the magnitude of the reflection amount itself but how much it has changed and obtains a detection signal based on the magnitude of the change, but in this way, the human body remains stationary. In this case, the amount of reflection does not change, so it cannot be detected.

In addition, since a human body detection signal is output when the difference in the amount of reflection described above continues for a predetermined period of time and exceeds a predetermined value, it is possible to prevent sunlight from reflecting off of snow and entering the light receiving unit, or from receiving direct or reflected sunlight. Since it does not output a human body detection signal when the sensor enters the area, it will not malfunction due to snowfall or sunlight. These drawbacks have also been resolved.

Effects of the invention When a human body enters the detection area under normal conditions, the first and second
Switches 24 and 25 are turned off and the second integrating circuit 1
Since the time constant of No. 3 is approximately infinite regardless of the resistance values of the first and second resistors 21 and 22, the integral value hardly increases even if the amount of reflection from the human body is input, and the sensitivity decreases. There are almost no

Normally, the second switch 25 is turned on, and the time constant of the second integrating circuit 13 becomes an intermediate value corresponding to the resistance value of the second resistor 22, so that the amount of reflection from the background can be integrated in a relatively short time.

After turning on the power, press the push button switch 26 for a predetermined period of time.
When turned on, the first and second switches 24 and 25 are turned on.
ON, the time constant of the second integration circuit 13 is the first and second
This is the minimum value corresponding to the resistance values of the resistors 21 and 22, and the amount of reflection from the background can be integrated in a short time.

[Brief explanation of the drawing]

1 to 4 show embodiments of the present invention.
Figure 2 is an explanatory diagram of the integration circuit, Figure 2 is a block diagram of the human body detection method, Figure 3 is a table diagram showing signal changes in each block, Figure 4 is a schematic diagram showing the mounting state of the emitter and receiver, FIG. 5 is an explanatory diagram showing an example of an integrating circuit. 3 is a photoreceiver, 12 is a first integration circuit, 13 is a second
Integrating circuit, 20 is a capacitor.

Claims (1)

[Claim for Utility Model Registration] The difference between the amount of reflection from the background and the amount of reflection from the human body is detected, and the human body is detected only when the difference in the amount of reflection is greater than a predetermined value and continues for a predetermined period of time. This is an integrating device used in a human body detection method that outputs a signal, and includes a first integrating circuit 12 on the output side of the light receiver 3 that has a small time constant and integrates the amount of reflection from the background and the human body;
A second integration circuit 13 whose time constant changes from almost infinite to an intermediate value and a minimum value and integrates the amount of reflection from the background.
are connected in parallel, and the first integrating circuit 12 is made up of a resistor 23b and a capacitor 23a that grounds the output side of the resistor 23b, and the time constant (resistance value x capacitor capacity) is set to a small value; 13, a first resistor 21 connected to the output side of the light receiver 3 via a first switch 24 which is turned ON for a predetermined time after the power is turned on and when the push button switch 26 is turned ON, and a first resistor 21 which is connected to the output side of the light receiver 3 and turned OFF when a human body enters the detection area. The light receiver 3 is connected via the second switch 25.
A second resistor 22 connected to the output side of (Resistance value x
When the first switch 24 is OFF and the second switch 25 is ON, the time constant is equal to the resistance value of the second resistor 22 and the capacitor 2.
When the first and second switches 24 and 25 are turned on, the time constant becomes the minimum value that matches the parallel resistance value of the first and second resistors 21 and 22 and the capacitance of the capacitor 20. What is claimed is: 1. An integrating device used in a human body detection method, characterized by having a configuration as follows.