JPH028780A - Human body detector - Google Patents

Abstract

PURPOSE:To judge the presence of a human body by simple and inexpensive constitution by a method wherein the peak values and output times of a plurality of infrared detection elements are detected from the outputs thereof when a human body is detected using difference between the quantities of infrared rays emitted from the moving human body and the background thereof and mutually compared while output order is considered. CONSTITUTION:An output-order judging part 51 is provided to a human body detector and the output rising order of a plurality of infrared detection elements A-D are calculated from the outputs thereof. When it is detected that the outputs of the elements provided diagonally appear in succession, an order-abnormality judgement signal for informing the order-abnormality is sent to a judging part 5 and, only when conditions are satisfied with respect to a peak value and output time and an order- abnormality judgement signal is not emitted from the output order judge part 51, it is regarded that a human body is detected. In such a case that the order-abnormality judgement signal is emitted from the judge part 51, even if two conditions described previously are satisfied, it is regarded that the human body is absent. By this method, erroneous operation is prevented even when there are internal noise, a temp. change and disturbance light.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an infrared receiving type that detects the difference between the amount of infrared rays emitted from the human body and the amount of infrared rays emitted from the background such as the floor surface by the movement of the human body. The present invention relates to a human body detection device.

[Prior art] An infrared receiving type human body detection device is a device that detects a human body by detecting the temperature difference between the human body and the background as a difference in the amount of infrared energy using an infrared detection element such as a pyroelectric element. , which has become widely contradictory in recent years, and along with this, improvements in reliability are required. Possible causes of malfunction of infrared-receiving human body detection devices include temperature changes within the detection area, internal noise, and the influence of high-energy disturbance light such as headlights and sunlight. Various proposals have been made in the past to eliminate causes of malfunction.

One of them is a method of arranging two infrared detection elements horizontally and using their differential outputs to detect a human body. This method can prevent malfunctions caused by changes in background temperature across the detection areas of both infrared detection elements, but when the human body moves in the vertical direction, the outputs of both infrared detection elements cancel each other out. , it has the disadvantage of not being able to provide output as a differential output. Furthermore, there is a risk of malfunction due to background temperature changes only within the detection area of one infrared detection element.

Therefore, a method of obtaining two sets of differential outputs using four infrared detection elements has been proposed (Japanese Patent Laid-Open No. 58-21339
FIG. 5 shows an example of the detection operation using this method. Four detection areas 1 to 2 are set on the object surface by four infrared detection elements, and differential outputs A and B are obtained from the detection areas 1 and 1, and the detection areas 1 and 2, respectively. In the case of FIG. 5(a), the human body is detected in the detection areas I, I[I to 11. IV, and both differential outputs A and B are obtained. In the case of FIG. 6B, the human body moves from detection areas I and II to ■ and ■, and differential outputs A and B are both obtained.

[Problem to be Solved by the Invention] However, in the case shown in FIG. 2(c), differential output A is obtained, but differential output B is detected in the detection area ■.

Since the human body simultaneously shuts down (1), the outputs are canceled and differential output B is not generated. Therefore, in order to reliably detect the movement of a human body, it is necessary to generate a human body detection output when either of the differential outputs A and H generates an output.

In this case, the differential output A due to temperature changes occurring within one sensing area.

There is a possibility that one of the B outputs may cause malfunction. Further, even if one infrared detection element produces an output due to internal noise or the like, one of the differential outputs A and B may produce an output, resulting in malfunction.

Therefore, the inventors of the present invention detect the presence or absence of a human body by extracting independent outputs from a plurality of infrared detection elements and calculating the ratio of the peak value and the variation in output time from the output of each infrared detection element. A system has been proposed (Japanese Patent Application No. 62-242090), but the output order of each infrared detection element has not been considered. For this reason, there is a problem in that a human body detection signal is generated even in cases where the order of the outputs of the infrared detecting elements cannot be considered to be due to the presence of a human body.

The present invention has been made in view of these points, and its purpose is to extract independent outputs from a plurality of infrared detection elements, and to determine the presence or absence of a human body by taking into consideration the order of the outputs. By doing so, it is an object of the present invention to provide a human body detection device that has a simple and inexpensive configuration and is highly reliable.

[Means for Solving the Problem] In order to achieve the above object, the present invention has the following features:
As shown in the figure, an optical system 1 that collects infrared rays from a detection area, a plurality of infrared detection elements A to D that receive the infrared rays collected by the optical system 1, and a plurality of infrared detection elements A to D
an amplifying section 3 that amplifies each output of D, a signal processing section 4 that processes each output of the infrared detection elements A to D amplified by the amplifying section 3 into a signal suitable for human body detection; Detect the peak la V A~·VD and the output time tA~to from each output of the infrared detecting elements A~D processed by,
Judgment unit 5 that compares these with each other to determine the presence or absence of a human body.
and an output unit 6 that outputs the determination result of the determination unit 5, an output order determination unit that determines the presence or absence of a human body based on the order of rise of each output of the infrared detection elements A to D. 51 is added to the determination unit 5.3 [Function] In the present invention, as described above, the infrared detection elements A to D
Peak value vA~Vo and output time t^~to
The determination unit 5 that detects and compares these with each other to determine the presence or absence of a human body is provided with an output order determination unit 51 that determines the presence or absence of a human body based on the order in which the outputs of the infrared detection elements A to D rise. Therefore, if the order of the outputs of the infrared detection elements A to D cannot be considered to be due to the presence of a human body, no human body detection signal is generated, and therefore no noise This makes it possible to reduce the probability of false detection caused by such factors.

[Example 11 FIG. 1(,) is an overall configuration diagram of an embodiment of the present invention.

The optical system 1 that collects infrared rays uses a mirror or a lens. When providing a plurality of detection areas, a multi-segment mirror or a multi-segment lens is used to collect infrared rays from the plurality of detection areas. As the infrared detection elements A to D, pyroelectric elements are used which are inexpensive and can operate at room temperature. In addition to the pyroelectric element, a thermomobile can also be used. Multiple infrared detection elements A
By arranging ~D on the focal plane 2 of the optical system 1, multiple detection areas A~D° on the object plane through the optical system 1 are arranged in the same way as the infrared detection elements A~D on the focal plane 2. As the human body moves within the detection areas A° to D°, each of the infrared detecting elements A to D produces an output as a change in temperature difference with the background. In the amplifying section 3, the outputs of the infrared detecting elements A to D are each independently amplified. In the signal processing section 4, a bandpass filter is provided to extract only necessary frequency components from each output. Each output that has passed through the bandpass filter is sequentially A/D converted using a multiplexer and an A/D converter. Each A/D converted output is sent to a micro combinator μC that constitutes the judgment unit 5.
In the determination unit 5, the characteristics of each output waveform are determined by the peak value (1) to VD and the time at which the output exceeds a certain level (8 to t).

2. The presence or absence of human body detection is determined by mutually comparing the peak value (2) to VD and the output time tA to to for each output.

FIG. 1(b) shows the main structure of an embodiment of the present invention. As shown in the figure, four infrared detection elements A to D are arranged on the focal plane 2 of the optical system 1.

At this time, detection areas A° to D′ are formed on the object surface by the optical system 1 in the same arrangement as the arrangement of the elements, but the size of the human body is such that it covers each detection area A to D′. Design the optical system l.

Figures 2 (a) to (c) show main examples where a human body passes through detection areas A'-D'' and the output waveforms of each infrared detection element A to D in that case. First, each output Waveform peak M
When considering V to V, it is considered that the human body passes through the entire detection area A° to D' regardless of the direction of movement when the human body moves, so similar peak values are obtained. Here, the temperature distribution on the surface of the human body and the detection areas A~D
Considering the difference in the area of the human body surface occupied by the output, there will be some variation in the peak values ■A to V of each output.The peak values ■A to VD are also affected by the ambient temperature. , when the ambient temperature is low, the peak value increases, and when it is high, it decreases.Therefore, it is only necessary to perform a relative calculation for each peak value vA~■D, and the maximum value at each peak value vA~■D is With VIallX and 4-, a threshold level is set based on VIIIax, and when all other peak values exceed the threshold level, it is determined that a human body is present.

That is, the minimum value VII at each peak value VA to VD
The following equation may be satisfied for the threshold level K (0<K<1) where the ratio of Ii n and the maximum value Vmax is satisfied.

Vmin/Vwax＞K
---■Next, focusing on the output time LA%to, when a human body moves through all detection areas A° to D', it moves from one detection area to another regardless of the direction of movement. There are two detection areas that require travel time. The travel time is indicated by the time difference between the output times at which the outputs of the infrared detection elements A to D rise. This time difference is limited to a certain range by considering the size of the detection area and the moving speed of the human body.The moving speed of the human body is from sIl:u+/sec) to S2Cm/see:]
(Sl<82), the lower limit speed S
1, the upper limit value T2 (see) of the time difference can be determined, and the lower limit value T, [5ee] of the time difference can be determined with respect to the upper limit speed s2. If the time difference between the output times is Δt, it is determined that a human body is present when the following equation is satisfied.

T, Δ1, T2 ...■ In Figure 2, if we take the time difference between the output time of the most tJ) and the output time of the most tJ in Figure 2, then (,) (b)
, (c), the time difference is determined by setting AL=to- to 8, and whether or not this satisfies the equation 0 is determined by °
1'+1 should be constant.

Although a human body can be detected with accuracy of 74 degrees using the above two determination conditions, in order to further reduce the amount of work required, the order in which the outputs of the infrared detection elements A to D rise is determined. First, as described above, the times 1A to 1to at which the outputs of the respective infrared detection elements A to D rise are determined and their order is determined.

FIG. 3 shows the moving directions (a) to (11) of the human body, and the infrared detection elements A to 1 for each moving direction (u) to (11).
The output of D is shown in FIGS. 4(a) to 4(11), respectively.

As can be seen from FIGS. 4(,) to (11), the output order of the infrared detection elements A to D differs depending on the moving direction of the human body.

In the moving direction (a), the outputs of infrared detection elements A and B rise almost simultaneously, and then the outputs of infrared detection elements C and
The outputs of D rise almost simultaneously.

In the moving direction (b), the output of the infrared detecting element A rises first, followed by the output of the infrared detecting element BC, and the outputs of the infrared detecting elements rise starting from the first. As described above, depending on the direction of movement of the human body, the order in which the infrared detection gamma rays rise appears regularly. In other words, there is an order of rises that will never occur. For example, in the movement direction (IJ), the output of infrared detection element A rises first, but the output of infrared detection element A never rises second; and in the movement direction (a), Although the outputs of the infrared detection elements A and B rise almost simultaneously, there is a difference in the rise time due to various conditions such as the movement of the body at the time of intrusion and the unevenness of the human body. Here, if the output of infrared detecting element A rises first, the output of infrared detecting element B will necessarily rise second, and the output of infrared detecting element A will be the third at the earliest, never the second. In this way, it is impossible for an element whose output is diagonal to the element whose output rises first to rise second.

Based on the above, the output order determination section 51 is provided to determine the rise order of the output of each element from the outputs of the plurality of infrared detection elements A to D, and as described above, the output of the elements having a diagonal positional relationship is determined. ”1i, an order abnormality determination signal is sent to the judgment unit 5 to notify the order abnormality.
As described above, in the judgment unit 5, only when the conditions regarding the peak value and the output time are satisfied and there is no order abnormality judgment signal from the output order judgment unit 51, the human body is deemed to be detected i-, and the output order is judged. If there is an order abnormality determination signal from the unit 51, it is assumed that no human body exists even if the above two conditions are met.

By using such a determination method, the internal Xtff
It is possible to prevent malfunctions caused by general or local temperature changes or ambient light, and it is possible to detect a human body with high precision.

[Effects of the Invention] As described above, the present invention provides an infrared receiving type human body detection device that detects the difference between the amount of infrared rays 1 emitted from the human body and the amount of infrared rays emitted from the background by the movement of the human body. The device detects the peak value and output time from the output of each infrared detection element, compares these with each other, and also takes into account the output order of each infrared detection element to determine the presence or absence of a human body. Therefore, there is an effect that highly reliable human body detection can be performed with a simple and inexpensive configuration.

[Brief explanation of the drawing]

FIG. 1(a) is a block diagram showing the overall configuration of the present invention, FIG. 1(b) is a configuration diagram of the main parts of the same as above, FIGS. 2 to 4 are explanatory diagrams of the same as above, and FIG. 5 is a conventional FIG. 3 is an explanatory diagram of an example operation. 1 is an optical system, 2 is a focal plane, 3 is an amplification section, 4 is a signal processing section, 5 is a judgment section, 6 is an output section, A, I3. C. D is an infrared detection element, and 51 is an output order determining section.

Claims (1)

[Claims] (1) An optical system that collects infrared rays from a detection area, a plurality of infrared detection elements that receive the infrared rays collected by the optical system, and an amplifier that amplifies each output of the plurality of infrared detection elements, respectively. , a signal processing section that processes each output of the infrared detection element amplified by the amplifier section into a signal suitable for human body detection; and a signal processing section that detects the peak value and output time from each output of the infrared detection element processed by the signal processing section. In a human body detection device comprising a judgment unit that compares these with each other to determine the presence or absence of a human body, and an output unit that outputs the judgment result of the judgment unit, the detection unit detects the presence of a human body based on the rising order of each output of the infrared detection element. A human body detection device characterized in that an output order determining section for determining the presence or absence of a human body is added to the determining section.