JPS61284689A - Body detecting method - Google Patents

Abstract

PURPOSE:To detect a human body accurately by outputting a human body detection signal according to the difference in the quantity of light between the background and human body. CONSTITUTION:Infrared rays are projected by a projector 2 with a driving signal P1 from a projector driving circuit 8. When the human body enters a detection area, the quantity of reflected light increases and the output of a photodetector 3 also increases. Its output is sent to a sample holding circuit 10 through an amplifier 9 and held with a timing signal P2 from a timing signal generator 11 and the output of the circuit 10 is inputted to integration circuits 12 and 13. The time constant of the circuit 13 is set small, so the quantities of reflected light from the background and human body are obtained at the same time; and the time constant of the circuit 12 is set large, so even when the human body enters the detection area, there is no abrupt variation and the background level before the entry is held for a certain time, thereby obtaining the quantity of reflected light from the background. The outputs of the circuits 12 and 13 are supplied to a differential amplifier 14 to detect the output difference between the circuits 12 and 13, namely, the difference in the quantity of reflected light between the background and human body, thereby outputting the human body detection signal when this difference in the quantity of reflected light exceeds a specific value for longer than a specific time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for detecting a human body in an automatic door.

2. Description of the Related Art An automatic door detects when a human body approaches the door, outputs an opening/closing signal in response to the opening/closing operation, and various methods are known for detecting a human body.

For example, a human body detection method is known that includes a projector that emits infrared light and a receiver that receives the infrared light reflected from the human body, and outputs a detection signal when the receiver receives the infrared light. .

Problems to be Solved by the Invention If sunlight enters the receiver either directly or reflected from some object, a detection signal will be output, which may cause the door to malfunction.

When the infrared light emitted from the projector is reflected by the snow and enters the receiver, a detection signal is output, which may cause the door to malfunction.

It cannot be detected when the human body is stationary.

Measures and effects for solving the problem Based on the background of the infrared light emitted from the projector and the output of the receiver that receives the reflected light from the human body, the difference between the amount of reflection from the background and the amount of reflection from the human body. By determining the difference in reflection amount and outputting a human body detection signal when the difference in reflection amount continues for a predetermined time and exceeds a predetermined value, it will not malfunction due to changes in background conditions or time changes in the luminous efficiency of the floodlight, and will also prevent malfunctions due to snowfall or sunlight. The device does not malfunction and can detect a stationary human body.

Embodiment FIG. 4 is a schematic diagram showing how the emitter and the receiver are installed. The emitter 2 and the receiver 3 are installed on the ceiling 1, and the infrared light from the emitter 2 is directed toward the floor 4 and illuminates the irradiation area 5. The light is emitted as shown in , and the intersection of the light receiving area 6 of the light receiver 3 and the irradiation area 5 becomes 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.

FIG. 1 is a block explanatory diagram showing a human body detection method, and FIG. 2 is a front view showing signal changes of each block.
is the emitter drive signal (pulse) from the emitter drive circuit g
Pl emits infrared rays, and the output of the receiver 3 increases and decreases sequentially due to the intrusion of the human body as shown in FIG. The output level is sent to the sample-and-hold circuit 1o and held by the timing signal from the sample-and-hold timing signal generator 11.

The sample and hold timing signal generator 11
outputs the timing signal (pulse) Pa with a slight time delay from the projector drive signal P1 as shown in FIG. The output level is held until the next timing signal P2 is input, and the output is synchronized with the infrared light projection timing at 5, as shown in FIG. 2(E).

That is, the sample-and-hold timing signal generator 11 receives the projector drive signal P1 and outputs a timing signal P, which is necessary for a sample-and-hold operation in which the infrared light emission timing of the projector 2 is synchronized, to the sample-and-hold circuit 10. , the sample-and-hold circuit 1o holds and outputs the output level of the light receiver 3 amplified by the amplifier 9 every time the projector drive signal P1 is output.

The output level of the sample-and-hold circuit 10 is the first
It is integrated by the second integration circuit 12.13.

First integration circuit 120 time constant (resistance value x capacitor capacity)
is set to a small value, and the temporal change in its output becomes extremely large, as shown in Figure 2 (f), in order to capture the amount of reflection from the background and the human body at the same time.

The time constant of the second integrating circuit 13 is set to an extremely larger value than that of the first integrating circuit 12, and the temporal change in its output is similar to that of the second integrating circuit 13.
As shown in Figure ()), it is much smaller than that of the first integrating circuit, and even if the output level of the sample-and-hold circuit 10 increases rapidly, it does not reach that level quickly, and the human body Even if the human body enters the detection area 7, the output does not suddenly increase and the background level before the human body enters is maintained for a certain period of time, so that the amount of reflection from the background can be taken.

The output levels of the first and second integrating circuits 12 and 13 are sent to the differential amplifier 14, and the difference α between the output levels shown in FIG.
is amplified to obtain the output level shown in FIG. 2 (H).

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 if 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 O, OIV, it is necessary to amplify it.

The output level of the differential amplifier 14 is sent to the comparator 15, and the level set value A of the level setter 160 and K of FIG.
The second
As shown in the figure, the comparator 15 outputs a signal at a predetermined voltage level.

This signal pulse is output to the pulse width discrimination circuit 17, and the pulse width discrimination circuit 17 observes the time during which the signal pulse is output, and if the signal pulse is output for a predetermined time t1 or more, then
Until the signal pole stops (the output of comparator 15 is OFF)
As shown in Figure 2 (N), a signal island of a predetermined voltage level is output.

Here, the predetermined time 11 during which the signal melon is output is
Reflected light from snow or sunlight directly or reflected from the receiver 3
This is the time at which it is possible to distinguish between the time when the light receiver 3 outputs when the light is incident on the human body, and the time when the light receiver 3 receives and outputs the reflected light from the human body, and this makes it possible to malfunction due to snow or sunlight. This can be prevented.

In other words, since the reflected light from snow and sunlight enters the receiver 3 for a very short time, the time during which the signal is output from the comparator 15 described above is shorter than the predetermined time (pulse The width discrimination circuit 17 does not output a signal.

The signal & of the pulse width valve circuit 17 is input to a timer 18, and when the timer 18 receives the signal R2, the relay 1 is activated.
At the same time, the operation of relay 19 is stopped after a predetermined period of time has elapsed since the manual power was removed, and relay 19 is started to operate.
9 continues to output a human body detection signal to a controller (not shown) during operation.

In other words, when the signal R2 is input from the pulse width discrimination circuit 17 as shown in FIG.
9 is activated and even if it is no longer input) the set time tlI
is turned ON and the relay 19 continues to operate.

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 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 receiver, the human body detection signal will not be output, and the luminous efficiency of the projector will be reduced. 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 or a change in the amount of reflection from the floor surface, the human body detection signal is not output, so there is no malfunction.

It can also detect a stationary human body.

Note that the second integrating circuit 13 has a large time constant in order to capture only the amount of reflection from the background, and therefore has the following problem.

If the time constant is large, the amount of reflection from the background changes when the power is turned on or when the orientation of the emitter and receiver changes.
It takes too much time to reach the original integral value.

When the human body continues to be in the detection area, the integral value gradually increases and the difference with the output of the first integrating circuit 12 becomes smaller, resulting in a decrease in detection sensitivity.

When the human body that has been present disappears, it takes time for the integral value that has increased as described above to return to the original integral value.

Therefore, in the second integrating circuit 12, as shown in FIG. ,
A second switch 25 is connected in series to the second resistor 22, and the first switch 24 is connected to a push button switch 26 via a knot gate 27 and to a power source via a timer 28. is knot gate 2
The first switch 24 is connected to the output side of the pulse width discrimination circuit 17 through the switch 9, and the first switch 24 is turned on for a certain time (set by a timer) when the power is turned on and when the push button switch is pressed, and the second switch 24 is turned on for a certain time (set by a timer). 25 is connected so that it is turned off when the pulse width discrimination circuit outputs the signal Rs.

Since it is like this, when the power is turned on, the push button switch 26
Normally when the switch is OFF, no signal is input to the first switch 24, so it is OFF, and since the pulse width discrimination circuit 17 does not output the signal R2, a signal is input to the second switch 25, which turns ON.

Therefore, the capacitor 20 has second and third resistors 22 .
23 are connected in parallel, and the time constant T2 at this time is set to a value sufficient to carry out the above-mentioned integration operation.

Also, when the power is turned on and the push button switch 26 is turned on, the first switch 24 is turned on for the time set by the timer 28, so the capacitor 20 is connected to the first, second and third resistors 21.
, 22, and 23 are connected in parallel so that the combined resistance value is smaller than that described above, so the time constant T3 at this time becomes small.

(Ta>Ts) Therefore, when the power is turned on or when the directions of the emitter 2 and the light receiver 3 are changed, the time constant of the second integration circuit 130 can be made small to obtain the original integral value in a short time.

Furthermore, when the signal R11 is output from the pulse sub-discriminator circuit 17, the second switch 25 turns OFF L, and only the third resistor 23 is connected to the capacitor 20, and the resistance value at that time is large, so the time constant T1 at this time is the highest. growing. ('rx＞'
r,>'r,) Therefore, when the human body enters the detection area, the time constant of the second integrating circuit 130 becomes larger than normal, and the integral value is set so that the integral value does not increase too much if the human body continues to remain in the detection area. This can prevent a decrease in sensitivity, and when the human body that has been present for a long time is no longer present, the pulse width discrimination circuit 17 outputs a signal R2.
is no longer output and the second switch 25 is turned on, so the time constant becomes as small as Ta, and the integral value returns to the original integral value in a short time.

Effects of the Invention Since a human body detection signal is generated 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 there are temporal changes in the luminous efficiency of the floodlight or changes in the background condition, preventing malfunctions. It can detect even a stationary human body.

In other words, since the amount of reflected infrared light from the floor surface varies depending on factors such as 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. In this case, there is a slight temporal fluctuation in the level of the reflection amount itself due to the fluctuation in the amount of reflection mentioned above, so it is necessary to prevent this fluctuation from being detected. This makes it difficult to obtain a long detection distance.

To solve this problem, it would be better to use a differential operation type, which 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 that change. 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 that the human body detection signal may be reflected by snow and enter the light receiving section, or sunlight may be reflected directly or reflected from the light receiving section. Since it does not output a human body detection signal when it enters the
It does not malfunction due to snowfall or sunlight.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a block explanatory diagram showing a human body detection method; FIG. 2 is a color representation showing signal changes in each block; FIG. FIG. 4 is a schematic diagram showing how the projector and receiver are attached. 2 is the emitter, 3 is the receiver.

Claims (1)

[Claims] Emit infrared light from the projector 2, receive the infrared light reflected from the background and the human body by the receiver 3, and calculate the difference between the amount of reflection from the background and the amount of reflection from the human body based on the output of the receiver 3, A human body detection method characterized in that a human body detection signal is output when the difference in reflection amount continues for a predetermined time and is equal to or greater than a predetermined value.