JPH04225191A - Human organism detector - Google Patents

Abstract

PURPOSE:To correct the dispersion of sensitivity to prevent misjudgment in the case where a plurality of infrared sensors are used. CONSTITUTION:When a quantity of infrared energy made incident on a plurality of infrared sensors 11, 12 is equivalent, a correction factor for agreeing two outputs each other is calculated to correct the outputs of the infrared sensors 11, 12 in accordance with said correction factor. The presence of a human organism can be detected on the basis of the level of its difference by the use of a difference calculation part 18.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a human body detector that detects infrared rays emitted from a human body using an infrared detection element.

0002

[Prior Art] Conventional human body detectors using infrared rays include a detector using a pyroelectric infrared element having AC characteristics, and a human body detector using an infrared detector such as a thermopile having DC characteristics. ing. A human body detector using an infrared sensor such as a thermopile measures infrared rays within a detection area using direct current. As shown in FIG. 6A, such a detector discriminates signals from an infrared sensor such as a thermopile using a predetermined threshold value Vref1 to detect the presence or absence of a human body.

[0003] In human body detectors using infrared sensors having such direct current characteristics, the infrared sensor may be affected by ambient temperature changes, sunlight radiation, or floor temperature changes caused by air conditioning equipment, etc. output voltage drifts. Therefore, as shown in FIG. 6(b), if the output voltage becomes higher than the reference voltage Vref1, there is a drawback that the presence of a person is detected even though there is no person within the infrared detection range.

0004

[Problem to be solved by the invention] Therefore, Fig. 7 (a), (
As shown in FIG. 7(B), the infrared rays in the plurality of detection areas A and B are focused on the infrared sensors 2 and 3 by the concave mirror 1, and these infrared rays are calculated by the difference calculation unit 4 as shown in FIG. 7(B). It is conceivable to calculate the difference between the two, and when the difference exceeds a predetermined threshold value Vref2, the determination unit 5 determines that there is a person present. In this way, even if the outputs of the infrared sensors 2 and 3 have a temperature drift of ΔV per unit time as shown in FIG. 8(a),
B) When the difference exceeds the threshold level Vref2 as shown in c), a human body detection output can be output as shown in FIG. 8(a) d.

However, even with this configuration, 2
If there are variations in sensitivity between the two infrared sensors 2 and 3, there is a risk of malfunction. For example, as shown in FIG.
(V/min) and ΔV2 (V/min). In this case, the output of the difference calculating section 4 will undergo a temperature drift by (ΔV1 - ΔV2) (V/min). Therefore, even if the deceased enters detection area B and leaves this area, if the output of the difference calculation unit 4 exceeds the threshold value Vref2 due to the influence of drift,
As shown in FIG. 8(b)c and d, there is a drawback that the judgment unit 5 outputs a human body detection output.

The present invention has been made in view of the problems of human body detectors using a plurality of infrared sensors. The technical challenge is to provide a human body detector that is free from the risk of

[0007]

[Means for Solving the Problems] The present invention includes a plurality of infrared detection elements having DC output characteristics corresponding to the temperature of a detection area, a detection area that is divided into a plurality of partial areas, and an infrared ray of each partial area. A difference calculating section having a light focusing means for focusing light on each of the plurality of infrared detecting elements, a subtracter for detecting the difference in the output of each infrared detecting element, and an adder for adding the outputs, and an output of the signal processing section. An identification signal is output from a part that determines the presence or absence of a human body by making a discrimination based on a predetermined threshold value, a human body non-detection state identification means that identifies a state in which a human body does not come into the detection area of each infrared detection element, and a human body non-detection state identification means. A correction coefficient calculation unit that calculates a correction coefficient for matching the outputs from each infrared detection element when obtained, and a correction unit that corrects the output of the infrared detection element based on the output of the correction coefficient calculation unit. It is characterized by:

[0008]

[Operation] According to the present invention having such characteristics, the presence or absence of a human body is determined by using a plurality of infrared detection elements and calculating the difference between them. The human body non-detection state identifying means identifies that no human body has come to the detection area of any of the infrared detection elements. When such an identification signal is issued, it is calculated by a correction coefficient calculation unit to match the outputs of the infrared detection elements, and thereafter the output of each infrared detection element is corrected by the correction unit to eliminate variations in sensitivity. The presence or absence of a human body is accurately detected.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the structure of a human body detector according to a first embodiment of the present invention. As shown in this figure, in this embodiment, two infrared sensors having DC characteristics, for example, thermopiles, are used as infrared sensors 11 and 12. The detection area of the infrared sensors 11 and 12 is the mirror 13.
As shown in FIG. 7(a), the areas are adjacent to each other. Here, the mirror 13 is a condensing means that divides the detection area into a plurality of partial areas and focuses infrared rays of each partial area onto an infrared detection element. Now, the outputs of the respective infrared sensors 11 and 12 are applied to amplifiers 14 and 15, respectively. Amplifier 14
, 15 amplify the respective input signals, and their outputs are given to a correction coefficient calculating section 16. Also amplifier 15
The output is given to the difference calculation unit 18 via the correction unit 17,
The output of the amplifier 14 is directly given to the difference calculation section 18. The difference calculation unit 18 detects these output differences,
Consists of a subtracter and an absolute value circuit. The output of the difference calculation section 18 is given to the judgment section 19. The determining unit 19 determines whether a person has arrived in any of the detection areas by discriminating input signals using a predetermined threshold value. In this embodiment, correction is automatically performed so that the output levels of the two infrared sensors match during a time period such as midnight when no one is expected to come to the detection area. The timer section 20 is a human body non-detection state identification means that outputs a timing signal for performing a correction operation at midnight or the like,
The output is given to the correction coefficient calculating section 16. Further, the determining section 16 prohibits the trigger signal from the timer section 20 from being sent to the timer section 20 even in the middle of the night when the determining section is outputting an output.

Now, the output voltages V14(t) and V15(t) of the amplifiers 14 and 15 at time t are expressed by the following equations. V14(t) =A・K11・P11(t) +V
140 V15(t) =A・K12・P12(t
) +V150...(1) However, A
: proportionality constant P11(t),
P12(t): Amount of infrared energy incident on the infrared sensors 11, 12 K11, K12: Infrared sensors 11,
12 sensitivity V140, V150: Amplifier 1
Voltage offset values 4 and 15 Now, it is assumed that the correction unit 17 corrects the output of the infrared sensor 12 using the sensitivity K11 and the voltage offset value V140 of the amplifier 14 as a reference. It is assumed that the correction coefficient calculation unit 16 calculates the correction coefficient Kb and the offset value Vb0 using the following equation. Kb =K11/K12 Vb0=V140 -Kb ・V150 ・・
- (2) Also, the correction unit 17 uses the correction coefficient K calculated in this way.
b Using the offset value Vb0, calculate the output of V15 using the formula (1
), (2) and outputs V17(t) expressed by the following equation. V17(t) =Kb ・V15(t) +Vb0
=A・K11・P12(t) +
V150...(3)

As described above, the timer section 20 outputs a pulse for correction, for example at midnight, if the judgment section 19 does not detect a human body for a predetermined period of time, for example, three hours or more. FIG. 2 is a time chart showing the operation after pulse generation. 2(a) shows the output of the timer 20, and FIGS. 2(b) and 2(c) show the outputs of the amplifiers 15 and 14. Here, it is assumed that the outputs of the infrared sensors 11 and 12 change over time due to variations in their sensitivities as shown in the figure, and the amount of change per unit time is different. Now, when the timer output is obtained at time t5, the correction coefficient calculating section 16 reads the outputs of the amplifiers 14 and 15. This input signal V14 (t5), V15 (t5)
are respectively expressed by equation (4). V14(t5)=A・K11・P11(t5)+V
140 V15(t5)=A・K12・P12(t
5) +V150...(4) Then time t5
At time t6, a predetermined time has elapsed since then, the outputs of the amplifiers 14 and 15 expressed by the following equation are read again. V14(t6)=A・K11・P11(t6)+V
140 V15(t6)=A・K12・P12(t
6) +V150...(5)

The correction coefficient calculation section 16 calculates correction coefficients Kb and Vb0 based on these four values. Kb = K11/K12 = {V14(t6)-V14(t5)}/
{V15(t6)-V15(t5)} Vb0=V1
40 −Kb ・V150 =V14(t
6) - Kb ・V15(t6) ...(6) Then, after time t6, the process of equation (3) is performed using the correction coefficient Kb and Vb0 obtained by equation (6), and V17(t)
Output. In this way, the outputs of the corrector 17 and the amplifier 14 become equal, as shown in FIG. 2(d). Therefore, the output of the difference calculation unit 18 that calculates the absolute value of these differences is also shown in FIG. 2(e).
As shown in , it becomes 0, and the two infrared sensors 11,
It becomes possible to equivalently match the two sensitivities.

In the first embodiment described above, a human body detector is described in which the detection area is divided into two parts using two infrared sensors, but the same applies when the detection area is divided into three or more parts. It can be corrected by FIG. 3 is a diagram showing the configuration of a human body detector according to a second embodiment, which uses three or more infrared sensors 21a to 21n to detect the presence or absence of a human body. In this embodiment, infrared sensors 21a to 21n are arranged corresponding to a plurality of detection areas,
The output of each infrared sensor is given to a correction coefficient calculation section 23 and a correction section 24 via amplifiers 22a to 22n. The other configurations are the same as those of the first embodiment described above. In this case, the output V22a of the amplifiers 22a to 22n at time t
(t) to V22n(t) are expressed by the following formula. V22a(t)=A・K21a・P21a(t)
+V22a0 V22b(t)=A・K21b・P
21b(t)+V22b0 ・ ・V22n(t)=A・K21n ・P21n(t)
+V22n0...(7) However, A
: proportionality constant P2
1a(t), P21b(t) to P21n(t): Amount of infrared energy incident on the infrared sensors 21a, 21b to 21n K21a, K21b to K21n:
Sensitivity V22a0, V22b0-V22n0 of infrared sensors 21a, 21b-21n: Voltage offset value of amplifiers 22a, 22b-22n

The correction unit 24 calculates the sensitivity K21a of the infrared sensor 21a and the voltage offset value V22a of the amplifier 22a.
Corrections are made to the outputs of other elements using 0 as a reference. That is, correction coefficients Kb to Kn and offset values Vb0 to Vn0 shown in the following equation (8) are calculated. Next, the process shown in Equation (9) is performed using the correction coefficient of Equation (8) to correct variations in sensitivity of the infrared sensor and offset value of the amplifier, and the differences are calculated as outputs V24a(t) to V24n(t), respectively. A signal is output to section 18. Kb = K21a /K21b ・ ・ Kn = K21a / K21n Vb0 = V22a0-Kb ・V22b0 ・ ・ Vn0 = V22a0-Kn ・V22b0 ・・
・(8) V24a(t)=V22a(t) V24b(t)=Kb ・V21b(t)+Vb0・ ・V24n(t)=Kn ・V21n(t)+Vn0
...(9)

[0015] This correction coefficient is calculated when a trigger pulse is output from the timer section, as in the first embodiment in which the detection area is divided into two. For example, the amplifier 22
b output V22b correction coefficient Kb and offset value V
b0 is the amplifier 22a which is referenced to V22b(t)
It is calculated from the output V22a(t) of. Kb = K21a /K21b = {V22a(t6) −V22a(t5
) }/{V22b(t6) −V22b(t5) }
Vb0=V22a0-Kb ・V22b0
=V22a(t6) -Kb ・V22b(t
6) ...(10) In this way, the correction coefficient Kb
~Kn, Vb0~Vn0 are calculated in the same manner. In this way, variations in sensitivity can be corrected when the amount of infrared rays input to each infrared sensor is equal.

FIG. 4 is a block diagram of a human body detector according to a third embodiment in which a light amount sensor is used instead of a timer to correct the output of the infrared sensor. In this figure, 3
Reference numeral 1 denotes a light amount sensor such as a photodiode that detects the amount of light in a detection area, and its output is given to a light amount determining section 33 via an amplifier 32. The light amount determination unit 33 detects a state in which the amounts of infrared rays incident on the detection area are equal. In other words, it detects when there are no people in the detection area and there are no temperature fluctuations due to sunlight or air conditioning equipment, for example, when the lights in the room are turned off and the room is unoccupied.
When such a state is detected, a trigger signal is given to the correction coefficient calculating section 16. Here, a light amount sensor 31, an amplifier 3
2 and the light amount determining unit 33 constitute a human body non-detection state identifying means for identifying a state in which a human body does not come into the detection area of the infrared detection element.

Next, the operation of this embodiment will be explained. 5(a) is a diagram showing the output of the light amount sensor 31, and FIG. 5(b) is a diagram showing the output of the light amount determining section 33. As shown in this figure, the light amount determining unit 33 outputs a trigger signal as shown in FIG. 5(b) after a predetermined time Δt7 when the indoor light amount becomes equal to or less than the threshold value Vref3. In this way, the two infrared sensors 11, 1
Since the amount of infrared energy of 2 is almost the same, the 1st
As in the embodiment, the outputs can be corrected to match.

[0018]

Effects of the Invention As described in detail above, according to the present invention, when determining the presence or absence of a human body by dividing the infrared sensors into a plurality of regions using a plurality of infrared sensors having DC characteristics, the It is possible to correct variations in output level. Therefore, by determining the level of the difference in output, it is possible to accurately detect the presence or absence of a human body without being affected by the ambient temperature.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a human body detector according to a first embodiment of the present invention.

FIG. 2 is a time chart showing the operation of the first embodiment.

FIG. 3 is a block diagram showing the configuration of a human body detector according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing the configuration of a human body detector according to a third embodiment of the present invention.

FIG. 5 is a time chart showing the operation of the third embodiment.

FIG. 6 is a time chart showing an example of the operation of a conventional infrared detector.

FIG. 7(a) is a diagram showing an optical system portion of an infrared sensor having a plurality of detection areas, which is the premise of the present invention, and FIG. 7(b) is a block diagram showing the overall configuration.

[Fig. 8] (a) is a time chart showing the operation of the human body detection sensor in Fig. 7 when there is no variation in sensor sensitivity, and (b) is a time chart showing the operation when there is variation between the two infrared sensors. It is.

[Explanation of symbols]

11, 12, 21a to 21n infrared sensor 12
Mirrors 14, 15, 22a to 22n, 32 Amplifiers 16, 2
3 Correction coefficient calculation sections 17, 24 Correction section 18 Difference calculation section 19 Judgment section 20 Timer section 31 Light amount sensor 33 Light amount judgment section

Claims (1)

[Claims] 1. A plurality of infrared detection elements having DC output characteristics corresponding to the temperature of a detection area, a detection area divided into a plurality of partial areas, and infrared rays of each partial area transmitted to the plurality of infrared detection elements. a condensing means that condenses light respectively;
a difference calculating section having a subtracter that detects a difference in output of each of the infrared detection elements and an adder that adds the outputs; and determining the presence or absence of a human body by discriminating the output of the signal processing section using a predetermined threshold value. a human body non-detection state identification means for identifying a state in which a human body does not arrive in the detection area of each of the infrared detection elements; a correction coefficient calculation unit that calculates a correction coefficient for matching the output;
A human body detector comprising: a correction section that corrects the output of the infrared detection element based on the output of the correction coefficient calculation section.