JP3060601B2 - Human body detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a human body detecting device for detecting the presence of a person based on a radiation temperature and a temperature change in a detection area.

[0002]

2. Description of the Related Art Conventionally, there has been known a human body detecting device which detects infrared rays radiated from a human body using an infrared detector such as a thermopile to detect the presence of a person in a detection area. . This thermopile converts the absolute intensity of infrared rays emitted from the detection area into a DC signal and outputs the DC signal. As shown in FIG. 4 (a), when no person exists in the detection area, the output of the infrared detector is set to V, and the reference voltage V set higher than this is set.
If a value exceeding ref is obtained, it is determined that a person exists in the detection area.

[0003]

However, in a thermopile having a DC characteristic for detecting the absolute temperature radiated from an object or a person in the detection area, when a person enters the detection area, for example, a heating device is activated. If there is a rise in ambient temperature and floor surface temperature due to the presence of a person,
The output V changes. Then, as shown in FIG. 4 (b), after the heating device is activated or the ambient temperature and the floor surface temperature rise, even if a person goes out of this detection area, the output voltage V of the infrared detector becomes higher than the reference voltage Vref. May also be higher. For this reason, the human body detecting device determines that a person exists even though no person exists in the detection area, and it is not possible to accurately detect a person even if a person enters or exits the same detection area thereafter. Had.

The present invention has been made in view of such a conventional problem, and can automatically recover from an erroneous detection state even if the detection temperature increases due to a heat source other than a human body in the detection area. An object is to provide a human body detection device.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a human body detecting apparatus for detecting the presence of a person by means of radiated infrared rays, comprising a first infrared detecting element having a DC characteristic for detecting a radiation temperature in a detection area; A second infrared detecting element having an alternating current characteristic for detecting a change in the radiation temperature of the detection area, a maximum time setting means for setting an estimated maximum time that a person stays in the detection area, and a first infrared detecting element. The output exceeds the reference voltage,
A human body presence detecting means for determining that a person is present in the detection area when an AC output is detected by the second infrared detecting element; and a second infrared detecting means in which the output of the first infrared detecting element is equal to or less than the reference voltage. A human body absence detecting means for determining the absence of a person when the AC output of the element is not detected; and a signal indicating the presence or absence of the person from the human body presence detecting means and the human body absence detecting means are not detected. Reference voltage setting means for setting a reference voltage based on the output signal level of the first infrared detection element when the time set by the longest time setting means elapses when no AC output is detected from the infrared detection element. It is characterized by doing.

[0006]

According to the present invention having the above features, the first
The infrared ray detecting element detects the absolute radiation temperature radiated from the object and the person in the detection area, and the second infrared ray detecting element detects a change in the radiation temperature in the same detection area. The presence and absence of a person are detected by DC and AC signals from the two infrared detection elements. When these signals are not detected and an AC signal cannot be obtained, a reference voltage corresponding to a new ambient temperature is automatically set based on a value obtained from the first infrared detecting element after the time set by the longest time setting means. Set. Next, when the output of the first infrared detecting element exceeds the reference voltage and an AC signal is obtained when the person stops again in the detection area, it is determined that a person actually exists.

[0007]

FIG. 1 is a block diagram showing an entire configuration of a human body detecting apparatus according to one embodiment of the present invention. The first infrared detecting element 1 (hereinafter, referred to as a detector 1) is a detector having a DC characteristic for detecting an absolute radiation temperature from an object and a person in a detection area, and uses, for example, a thermopile. On the front surface of the detector 1, a Fresnel lens 1a is provided for specifying a detection area. The Fresnel lens 1a is a lens for collecting infrared rays radiated from within the detection area to the detector 1. The output of the detector 1 is supplied to an A / D converter 3 via an amplifier 2. On the other hand, the second infrared detecting element 4 (detector 4) is a detector having an AC characteristic for detecting a change in radiation temperature of the heat source, and uses, for example, a pyroelectric element. The detector 4 is also provided with the same Fresnel lens 4b as the detector 1. The Fresnel lenses 1a and 4a are installed to collect infrared rays from the same detection area. Detector 4
Is output through an amplifier 5 to a band-pass filter (BPF) 6
Given to. The BPF 6 is a filter having a pass band of, for example, 0.2 to 10 Hz, and its output is given to the A / D converter 3. The A / D converter 3 converts the analog output signals of the amplifier 2 and the BPF 6 into digital signals, respectively, and outputs the signals to a microcomputer (CPU) 7.

The output of both channels of the A / D converter 3 and the output of the DIP switch 8 in this embodiment are supplied to the CPU 7. The CPU 7 stores operation procedures in a program memory, and has functions of a reference voltage setting unit 7a, a human body presence detecting unit 7b, and a human body non-existence detecting unit 7c as described later. The dip switch 8 sets a minimum rest time Tm, which is a maximum time during which a person is expected to stay in the detection area.

Next, the operation of the human body detecting device will be described with reference to FIG.
This will be described with reference to the time chart of FIG. FIG. 2 shows the waveforms of the respective parts a to c in FIG. 1. When a person enters or exits the detection area of the detector 1, as shown in FIG. A changing signal is obtained. (B) shows an AC waveform output from the detector 4, and (c) shows an output waveform of the CPU 7. FIG.
3 shows a signal processing procedure of the CPU 7 when a person enters and exits the place where the human body detection device is installed.

For example, consider a case where the human body detecting device of the present embodiment is installed in an automatic teller machine (ATM). At the time of installation, the longest rest time Tm is set in advance by the dip switch 8. The longest stationary time Tm represents a predetermined elapsed time from the time when the AC output of the detector 4 is stopped, and for example, A
At the place where the TM is installed, it takes about one minute. At time t ₀ for starting the operation, first, in step 11 CPU 7 determines that no one to its output L. Then, a reference temperature higher than the ambient temperature by a specified temperature is set, and the detector 1
The voltage Vref1 is set as the output conversion reference voltage (step 12). In step 13, the output voltage V (t ₀ ) from the detector 1 is read together with the detector 4, and in step 14, it is checked whether or not the output of the CPU 7 is at the L level indicating that no person exists. Because there are no time t ₀ the human in the detection area, the radiation temperature emitted from an object other than a human becomes a low value. The output voltage V (t ₀ ) of the detector 1 indicates, for example, the temperature of the floor on which the human body detection device is installed, and it is assumed that the heating device installed in the same place is not operating. Also, no AC output is obtained from the detector 4 as shown in FIG. Therefore, unless a person enters the detection area, the process returns from step 15 to step 13, and C
PU7 holds the output at L level.

Next, in a loop of steps 13, 14, and 15,
If at time t ₁ person enters the detection region, the output of the detector 1 by radiant heat from the human body is increased as shown in FIG. 2 (a), a voltage higher than the first reference voltage Vref1 is output.
When the person moves in the detection area from the detector 4, an AC output shown in FIG. 2B is obtained. The pass band of BPF6 is set to a frequency corresponding to the movement of a person, and is 10 Hz.
It is determined that the signal of the temperature change that changes at the following speed is emitted from a person in the detection area. In this case step 15
From step to the step 16, and as shown in FIG.
7 outputs an H level signal indicating the presence of a person. Thereafter, the loop of steps 13, 14, 15, and 16 is repeated, and the CP
U7 holds the H level.

[0012] The person at the time t _2, as shown in FIG. 2 (a) is AT
It is assumed that a predetermined operation has been completed before M and the user has left the detection area. At this time, the AC output from the detector 4 disappears. However, if a person stays at the ATM and the floor temperature or the surface temperature of the ATM device rises due to the heat of the human body, or if the detected temperature rises due to the activation of a heating device, etc., FIG. As shown, the output voltage V of the detector 1
(T ₂ ) becomes higher than the initial voltage V (t ₀ ). This voltage V
Since (t ₂ ) is slightly larger than the first reference voltage Vref1,
Although there is actually no person in the detection area, C
The PU 7 continuously outputs the H-level signal. in this case,
The process branches from step 14 to step 17, and proceeds to step 18 because the output voltage of the detector 1 is higher than Vref1. Then, since the detector 4 does not output the AC signal, the process proceeds to step 19. Then, the measurement of the rest time T is started, and the rest time T is compared with the longest rest time Tm (step 20). Because of immediately after the time t ₂ rest time T has not reached the maximum rest time Tm, the output of the CPU7 returns to the previous step 13 remains held in the H level. The output of the CPU 7 indicates that the person is parked in the detection area. Such an erroneous detection state is a result of the fact that the ambient temperature of the detection area has risen due to the stoppage of the person despite the fact that no human movement occurs and the AC output from the detector 4 becomes zero. is there.

[0013] Now still time from the time t ₂ in step 19 T
Is measured, and in step 20, the longest rest time Tm
Is compared to If the quiescent time T is less than the longest quiescent time Tm, the process returns to step 13 and repeats the same processing.
As shown in FIG. 2C, the CPU 7 holds the output at the H level. Elapsed time from the time t ₂ longest still time Tm more
In t _3, the process proceeds from step 20 to step 21, while the output of the CPU7 the L level, further updates only high voltage Vref2 as a reference voltage ΔV from the voltage V (t ₂₎ as shown in FIG. 2 (a) (Step 22), and return to Step 13.

[0014] Next, at time t ₃ unmanned state for a while from the continued, when a new person came at time t _4, the detector 1 and the detector 4, the time t in FIG. 2 (a), (b) An output waveform similar to the waveform from ₁ is obtained. In this case, steps 13, 14,
The process proceeds to step 16 via 15, and the CPU 7 outputs an H-level signal indicating that a person is present again. The output level of the detector 1 when this person has exited at the time t ₅ is lower than the voltage Vref2, becomes the same level as the voltage V (t _2), also eliminates the AC output from the detector 4. Therefore, the process proceeds from step 14, 17 to step 23, and an output indicating that the person no longer exists is output to the CPU.
7 to an output unit 9. Thus even if already changed ambient temperature in the detection area, upon entering the time t ₄ the person can accurately detect the presence or absence of a person automatically updates the reference voltage. In this way, in the present embodiment, the presence of a person after erroneous detection, which cannot be detected unless the CPU 7 is manually reset in the related art, can be automatically corrected and detected.

Here, when the time set by the longest time setting means has elapsed in steps 18 to 22, the CPU 7
The function of the reference voltage setting means 7a for setting the reference voltage based on the output signal level of the detector 1 is achieved. And C
The PU 7 comprises steps 15 and 16 in which a human body presence detecting means for determining that a person exists in the detection area when the output of the first infrared detecting element exceeds the reference voltage and the AC output is detected by the second infrared detecting element. Steps 17 and 23 are performed when the output of the first infrared detecting element is equal to or lower than the reference voltage and the AC output of the second infrared detecting element is not detected. The function of the absence detecting means 7c is achieved. In this embodiment, the dip switch 8 is used as the maximum time setting means, but a variable resistor or a rotary switch may be used. The reference voltage Vref1 in this embodiment is determined by the environment in which the human body detection device is installed, and the second reference voltage Vref2 is the maximum resting time Tm of a person expected in an ATM or other equipment. The ambient temperature after the lapse has been set, and these values differ depending on the place where each human body detection device is installed. In this embodiment, a thermopile is used as the first infrared detecting element having a DC type characteristic. However, a similar configuration can be made by using a thermistor bolometer or the like. Second
A similar effect can be obtained by using a microwave element instead of the infrared detecting element.

[0016]

As described above in detail, according to the present invention, a first infrared detecting element having a DC characteristic such as a thermopile and a second infrared detecting element having an AC characteristic such as a pyroelectric element are combined. With this arrangement, even when a person stops in the detection area, the stop of the person can be accurately detected. From the point in time when both the outputs of the first and second infrared detecting elements decrease, the reference voltage is automatically set based on the output of the first infrared detecting element detected when the time set by the longest time setting means is exceeded. Has been corrected. Therefore, even if the radiation temperature radiated from other than the human body in the detection area changes, the effect that the presence or absence of a person can be accurately detected is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a human body detection device according to an embodiment of the present invention.

FIG. 2 is a time chart illustrating the operation of the present embodiment.

FIG. 3 is a flowchart illustrating the operation of the present embodiment.

FIG. 4 is a time chart showing an example of the operation of the conventional human body detection device.

[Explanation of symbols]

 1, 4 infrared detecting element 1a, 4a Fresnel lens 2, 5 amplifier 3 A / D converter 6 band-pass filter 7 CPU 7a reference voltage setting means 7b human body presence detecting means 7c human body absence detecting means 8 dip switch 9 output unit

Continuation of front page (72) Inventor Kenji Matsui 10 Omron Co., Ltd., Hanazono Todocho, Ukyo-ku, Kyoto-shi (56) References JP-A-3-42592 (JP, A) JP-A-2-196931 (JP) JP-A-3-32329 (JP, A) JP-A-4-339292 (JP, A) JP-A-2-129525 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB G01V 8/20 G01J 5/12 G08B 13/19

Claims (1)

(57) [Claims] 1. A human body detection device for detecting the presence of a person by using radiated infrared rays, comprising: a first infrared detection element having a DC characteristic for detecting a radiation temperature in a detection area; A second infrared detecting element having an alternating current characteristic to be detected, a longest time setting means for setting an expected maximum time during which a person stays in the detection area, and an output of the first infrared detecting element sets a reference voltage. A human body presence detecting means for determining that a person is present in the detection area when an AC output is detected by the second infrared detecting element, and when the output of the first infrared detecting element is lower than the reference voltage. ,
A human body absence detecting means for determining the absence of a person when the AC output of the second infrared detecting element is not detected, and indicating the presence and absence of a person from the human body presence detecting means and the human body absence detecting means. When no signal is detected and no AC output is detected from the second infrared detection element, the reference is set based on the output signal level of the first infrared detection element when the time set by the longest time setting means elapses. And a reference voltage setting means for setting a voltage.