JPH01140279A - Number of persons detector - Google Patents

Abstract

PURPOSE:To correctly detect the number of persons by scanning the visual field of an infrared ray detecting element, removing the influence of a low frequency component included in a difference signal obtained by subtracting a reference waveform from an input waveform obtained thereby and detecting the number of the persons. CONSTITUTION:A light receiving output obtained by scanning the visual field of the infrared ray detecting element 2 is A/D converted by a signal processing part 4 and inputted to a decision part 5. In a reference waveform storing part 51, the input waveform when a human body is not present within the range of detecting is previously stored as the reference waveform. In a comparison part 52, the reference waveform is subtracted from the input waveform to form the difference waveform. In a low frequency component extracting part 53, only the low frequency component is extracted from the difference waveform and outputted. To the number of person detecting part 54, the difference waveform outputted from the comparison part 52 and the low frequency component outputted from the extracting part 53 are inputted. In the detecting part 54, a comparison operation is executed to form the waveform obtained by subtracting the low frequency component from the difference waveform and a maximum point on this waveform is counted, thereby, the correct number of the persons can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an infrared receiving type people detection device that detects the number of people by detecting infrared rays emitted from a detected human body.

(Background Art) Conventionally, a number of people detection device as shown in FIG. 6 has been proposed (Japanese Patent Application No. 61-281301). This number of people detection device includes an infrared detection element 2, a circular scanning optical system 1 that circularly scans the field of view of the infrared detection element 2, a preamplifier 3 that amplifies the output signal of the infrared detection element 2, and a preamplifier 3 that amplifies the output signal of the infrared detection element 2. a signal processing section 4 that converts the output signal of the amplifier section 3 into a signal necessary for detecting the number of people; a determining section 5 that determines the number of people based on the output signal of the signal processing section 4; and an output signal of the determining section 5. and an output section 6 that outputs information on the number of people, and is capable of detecting the number of people within a wide detection area with high precision.

In the judgment unit 5, the input waveform when there is no human body in the detection area is stored in advance as a reference waveform in the memory, and the input waveform is compared with the reference waveform in the memory to determine the presence or absence of a human body and the number of people. judged at the same time. Figure 7 is an explanatory diagram showing this situation, and the input waveform (Figure 7(b)
) and the reference waveform (FIG. 7(a)), and the result is used as a new difference waveform (FIG. 7(C)). In the differential waveform, the voltage level is almost zero in the part where the human body is not present, and an upwardly convex waveform appears in the part where the human body is present. The determination unit 5 detects maximum points for this difference waveform, and counts the number of maximum points as the number of people.

In this way, by storing the reference waveform in advance when the detected human body is not present as data indicating the background temperature distribution, and performing a comparison operation with the input waveform, the detection area can be easily influenced by environmental changes within the detection area. It is possible to detect the number of people without any trouble. However, in cases where multiple human bodies exist side by side in the scanning direction as seen from the detection device, in the difference waveform obtained by subtracting the reference waveform from the input waveform,
As shown in Figure 7(e), there is a problem in that it is difficult to detect the maximum points because low frequency components are superimposed.For example, in the case of Figure 7(c), there are three maximum points. Since the number of people detected should be three, the second maximum point has a small front-to-back slope, and the third maximum point is low in height, so it is difficult to detect it as a maximum point. There is a problem.

(Object of the invention) The present invention has been made in view of the above points, and
The aim is to create a people detection device that increases the accuracy of people counting by removing the influence of low frequency components superimposed on the difference waveform when multiple human bodies are present side by side in the scanning direction. It is about providing.

(Disclosure of the Invention) In order to achieve the above object, the number of people detection device according to the present invention has an infrared detection element 2 as shown in FIG.
, a scanning optical system 1 that scans the field of view of the infrared detection element 2, a preamplifier 3 that amplifies the output signal of the infrared detection element 2, and an output signal of the preamplifier 3 necessary for detecting the number of people. a signal processing unit 4 that converts the signal into a signal; a determination unit 5 that determines the number of people based on the output signal of the signal processing unit 4;
In the number of people detection device comprising an output section 6 that outputs number of people information from the output signal of the judgment section 5, the judgment section 5 includes:
a reference waveform storage unit 51 that stores in advance the output signal from the signal processing unit 4 when a human body is not present; and the signal processing unit 4
a comparison section 52 that compares the output signal from the reference waveform with the reference waveform in the reference waveform storage section 51 to obtain a difference waveform; and a low frequency component extraction section 53 that extracts only low frequency components from the difference waveform output from the comparison section 52. and a number of people detection section 54 that detects the number of people from the difference waveform outputted from the comparison section 52 and the low frequency component outputted from the low frequency component extraction section 53.

FIG. 2 is a diagram illustrating the configuration of the scanning optical system 1 used in the above-mentioned number of people detection device. This scanning optical system 1 is constructed by using a motor 12 to rotate a rotary plate 10 on which a concave cylindrical mirror 11 is attached so that its generatrix direction is parallel to the radial direction. The rotation axis 13 of the rotary plate 10 is arranged on the visual field center C of the light-receiving surface of the infrared detection element 2. Infrared rays emitted from the background or the human body are
The light is reflected by a mirror 11 attached to a rotating plate 10 and guided to an infrared detection element 2 . FIG. 3 is a diagram showing the instantaneous field of view F and the entire field of view S by the scanning optical system 1.

The instantaneous field of view F is rotated and scanned as shown by arrow A with the center of field of view C of the infrared detection element 2 as an axis, and the entire field of view S is circular.
It forms the

Infrared energy collected by the scanning optical system 1 is received by an infrared detection element 2 and converted into an electrical signal. After the output of the infrared detection element 2 is amplified by the preamplifier 3,
The signal is input to the signal processing section 4.

In the signal processing section 4, first, the input signal is input to a bandpass filter to cut unstable low frequency components and unnecessary high frequency components, thereby improving the S/N ratio.

The output of the bandpass filter is A/D converted and input to the determining section 5.

FIG. 4 is a diagram for explaining the operation of the determining section 5 in one embodiment of the present invention. Below, referring to Figure 4,
The operation of the present invention will be explained.

The output signal from the signal processing unit 4 has the input waveform (Fig. 4(b)
reference) is input to the judgment unit 5. Reference waveform storage unit 5
1 stores in advance an input waveform when there is no human body within the detection range as a reference waveform (see FIG. 4(a)). The comparison unit 52 subtracts the reference waveform from the input waveform to generate a difference waveform (see the solid line in FIG. 4(c)). The low frequency component extractor 53 extracts low frequency components (see FIG. 4(e)) from this differential waveform using a low pass filter or the like.
(see dashed line) is extracted and output. Needless to say, this low-pass filter may be constructed from a digital filter. The number of people detection unit 54 receives the difference waveform output from the comparison unit 52 and the low frequency component output from the low frequency component extraction unit 53. The waveform obtained by performing a comparison calculation between the two components and subtracting the low frequency component from the difference waveform (Figure 4 (d)
), and by counting the maximum points of this waveform, the number of people is detected. In the case of Figure 4(d),
Since there are three maximum points, the number of detected people is determined to be three. Note that methods for determining the maximum point include, for example, a method in which a point where the amplitude is greater than or equal to a predetermined value is determined to be a maximal point, and a method in which a point where the longitudinal slope is greater than or equal to a predetermined value is determined to be a maximal point. , these methods are used alone or in combination to determine local maximum points, and the number is detected as the number of people.

FIG. 5 is a diagram for explaining the operation of the determining section 5 in another embodiment of the present invention. Fig. 5(a) shows the 9-ray waveform, Fig. 5(b) shows the input waveform, the solid line in Fig. 5(c) shows the differential waveform, and the broken line shows its low frequency component.
, ) to (e). That is, in this embodiment, the operations of the reference waveform storage section 51, comparison section 52, and low frequency component extraction section 53 are the same as in the embodiment shown in FIG.
Only the operation of the number of people detector 54 is different. The number of people detection unit 54 of this embodiment compares and calculates the slope of the difference waveform output from the comparison unit 52 and the slope of the low frequency component output from the low frequency component extraction unit 53, 5(d)) is greater than a predetermined positive threshold A + , A
2.

A3. . . . , and then a set (A + , B
l), (A 2.82).

(A3.B3), by counting the number of...
The number of local maximum points is detected and the detected number is output as the number of people information. In the case of No. 5121(d), since there are three sets as described above, the number of detected persons is determined to be three.

In the output section 6 of the fit f&, the number of people information is displayed based on the number of people information given from the judgment section 5, and is transmitted to a remote point as necessary.

(Effects of the Invention) As described above, the present invention provides an infrared receiving type people detection device that detects the number of people by detecting infrared rays emitted from a human body to be detected. Since the number of people is detected by removing the influence of low frequency components included in the difference waveform obtained by subtracting the reference waveform from the waveform, it is possible to accurately detect the number of people even when there are multiple detected human bodies lined up in the scanning direction. This has the effect of being able to detect the number of people.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of the present invention, FIG. 2 is a schematic configuration diagram of a scanning optical system used in the above, FIG. 3 is an explanatory diagram showing the field of view of the same, and FIG. 4 is an embodiment of the present invention. FIG. 5 is a waveform diagram for explaining the operation of another embodiment of the present invention, FIG. 6 is a block diagram of the conventional example, and FIG. 7 is a waveform diagram for explaining the operation of the same example. FIG. 1 is a scanning optical system, 2 is an infrared detection element, 3 is a preamplification section, 4 is a signal processing section, 5 is a judgment section, 6 is an output section, 51 is a reference waveform storage section, 52 is a comparison section, 53 is a low The frequency component extractor 54 is a number of people detector.

Claims (1)

[Claims] (1) An infrared detection element, a scanning optical system that scans the field of view of the infrared detection element, a preamplification section that amplifies the output signal of the infrared detection element, and an output signal of the preamplification section that is used to detect the number of people. In a number of people detection device that includes a signal processing unit that converts into a necessary signal, a determination unit that determines the number of people based on the output signal of the signal processing unit, and an output unit that outputs number of people information from the output signal of the determination unit. , the determination unit compares the output signal from the signal processing unit and the reference waveform of the reference waveform storage unit with a reference waveform storage unit that stores in advance the output signal from the signal processing unit when a human body is not present. a comparison section that calculates a difference waveform; a low-frequency component extraction section that extracts only low-frequency components from the difference waveform output from the comparison section; A number of people detection device comprising: a number of people detection section that detects the number of people from a low frequency component.