JPS63134990A - Person number detecting device - Google Patents

Abstract

PURPOSE:To measure the number of persons with high accuracy even if a detection area is wide, by measuring the number of persons by counting the maximum value of a signal obtained by scanning circularly the visual field of an infrared-ray detecting element. CONSTITUTION:A scanning optical system scans the visual field of an infrared ray detecting element. An output of the infrared-ray detecting element 2 is amplified 3, allowed to pass through a band-pass filter 41, and thereafter, A/D- converted 42, and outputted to a microcomputer 51 for constituting a judgement part 5. The microcomputer 51 inputs data of an input waveform accumulated in an input buffer, by one period portion of a circular scanning optical system 1. Subsequently, the microcomputer 51 reads out a reference waveform stored in advance from a memory, and subtracts it from the input waveform. As a result, a comparison processing waveform is generated. From this comparison processing waveform, the detection of the maximum point, and the counting of the detected maximum point are executed, and based on a result of counting of the maximum point, person number information is outputted.

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 device for detecting the number of people has been proposed that uses a television camera to capture image data in a detection area and performs image processing on the image data to obtain an output for determining the number of people. The method of measuring the number of people by detecting human bodies based on changes in brightness due to light has a poor S/N ratio and does not provide sufficient detection accuracy. Therefore, in order to improve detection accuracy, attempts have been made to store image data in which no human body is present as reference image data in advance and compare this with input image data. It was difficult to distinguish between The processing of such a device for detecting the number of people using a television camera is generally complicated, and the current situation is that sufficient accuracy in detecting the number of people cannot be obtained despite the large size of the system. Furthermore, when using a television camera.

There is a risk of infringing on privacy, and there are many cases where this is not practical.

In addition, attempts have been made to irradiate near-infrared light and capture near-infrared radiation from the human head, especially hair, with a near-infrared camera, but a new near-infrared irradiation light source is required. Furthermore, there is a problem in that when hair cannot be detected, for example, when a person is wearing a hat, or even when the hair is gray, it cannot be detected as a human body.

Furthermore, if we try to improve human body detection ability by using an infrared camera instead of a television camera that uses visible light,
There are problems in that the cost is high, the system is complicated, and it lacks versatility.

On the other hand, a device using an infrared detection element and a scanning optical system has been proposed as a device for detecting the degree of congestion in elevators, etc. (Japanese Patent Laid-Open No. 59-60587).

(Japanese Patent Application Laid-open Nos. 59-83078 and 60-63487), these devices require the use of a large number of infrared detection elements in order to obtain a wide field of view, and also suffer from variations in sensitivity distribution within the detection area. There is a problem that there is a dead zone, and the result of detecting the number of people varies depending on the position and posture of the human body, making it impossible to obtain sufficient accuracy in detecting the number of people.

(Object of the invention) The present invention has been made in view of the above points, and
The purpose is to provide a highly accurate number of people detection device having a wide detection area with a simple and inexpensive configuration.

(Disclosure of the Invention) Figure 5 is a block diagram showing a schematic configuration of the present invention. The number of people detection device of the present invention includes an infrared detection element 2, 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 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 the determining section 5.
The scanning optical system 1 is a circular scanning optical system 1 that circularly scans the field of view of the infrared detection element 2, and the determining section 5 is configured to detect the number of people from the output signal. It is configured to detect the number of people by counting the maximum points of the output signal from the processing section 4, and is capable of detecting the number of people within a wide detection area with high precision.

First, the circular scanning method used in the present invention will be explained. When the human body to be detected is viewed from above, it is as shown in FIG. This is the height 1 shown in Figure 6(a).
A rectangular parallelepiped with dimensions of 70cn+, width 50cm, and depth 20c- is used as a model of an upright human body, as shown in Figures 6(b) and (c).
As shown in , four human body models TrL1 to 'rrL4 are arranged at the vertices of a square with one side of 3111, and the human body model 'rrL1 is projected onto a plane parallel to the floor surface U at a point three inches above the floor surface U. ~As is clear from Figure 0, which is a two-dimensional image by TrL4, the human body image seen from above is centered at the visual field C.
, the side of the human body is also seen, and the image extends in the radial direction from the center of visual field C. Also,
The farther the position of the human body is from the center of visual field C, the more the human body image becomes elongated in the radial direction. Considering the above points, as shown in Fig. 8, a rectangular slit-shaped viewing plane F is provided and a circular scanning method is used in which the viewing plane F is rotated around its end point to effectively and efficiently scan the human body. can be detected, identified, and counted. FIG. 8 shows the scanning situation using the circular scanning method, where F is the field of view, Q is the scanning direction, and F o is the total effective field of view. Also, 1
1 is the rotation center of the field of view F, which coincides with the field of view center C of the infrared detection element 2.

Using this scanning method, the four human body models shown in Fig. 6(a) are arranged as shown in Fig. 6(b) and (c), and the situation is circularly scanned from above at each time. FIG. 9 shows one period of the incident energy change on the rectangular slit-shaped viewing plane F in . However, it is assumed that the surface of the human body models 'rrt1 to m4 has a higher temperature than the floor surface U, and therefore the radiated infrared energy is also larger.

Since the infrared detection element 2 has a characteristic that the larger the incident energy, the larger the output signal, the convex portions above 41Il in the waveform shown in FIG. ? It+44. J [; is doing. In the present invention, the number of people is detected by detecting maximum points in the output signal from the infrared detection element 2 and counting the number of detected maximum points.

Reality 1''LL FIG. 1 is a diagram for explaining an example of a local maximum point detection method. As shown in FIG. 1, there is a characteristic that the polarity of the slope is reversed before and after the maximum point. Therefore, a point where the polarity of the slope is reversed can be detected as a maximum value.

FIG. 10 is a block diagram showing the circuit configuration used in this embodiment. The output of the infrared detection element 2 is amplified by the preamplifier 3 and then input to the bandpass filter 41. As the infrared detection element 2, a pyroelectric element that does not require cooling and is inexpensive is used. Since this pyroelectric element contains many low frequency components as background noise, the bandpass filter 41 cuts out unstable low frequency components and also cuts unnecessary high frequency components to improve the S/N ratio. . The output of the bandpass filter 41 is input to the A/D converter 42.
2, the signal is A/D converted and output to the microcomputer 51 constituting the determining section 5.

The motor drive section 12 operates according to a control signal from the microcomputer 51, and drives and stops the motor as necessary. In the rotation period detection section 13, a synchronization signal is outputted to the microcomputer 51 every rotation in synchronization with the scanning of the circular scanning optical system 1. The microcomputer 51 sequentially captures data from the A/D converter 42 every rotation of the circular scanning optical system 1 based on the synchronization signal from the rotation period detection section 13 .

FIG. 11 is a flowchart for explaining the operation of the determining section 5 in this embodiment. A predetermined number of data are sent from the A/D converter 42 in the signal processing section 4 at equal angular intervals for one cycle of the circular scanning optical system 1, and are stored in the input buffer of the microcomputer 51. When the microcomputer 51 is interrupted by a synchronization signal from the rotation period detection section 13, the microcomputer 51 first takes in data of the input waveform accumulated in the input buffer for one period of the circular scanning optical system 1.

In the microcomputer 51, input waveforms obtained when a human body does not exist within the detection area are stored in advance in the memory as reference waveform data. The microcomputer 51 reads this pre-stored reference waveform from the memory and subtracts it from the input waveform, thereby generating a comparison processing waveform. From this comparison processing waveform, the first
Detection of local maximum points as shown in the figure and counting of detected local maximum points are performed, and number of people information is output based on the result of counting local maximum points. Note that if the number of detected persons is 0, the reference waveform is updated by the input waveform.

The output unit 6 displays the number of people information based on the number of people information given from the microcomputer 51. In a conference room, etc., the number of people or the degree of congestion is displayed outside the room so that others can grasp the usage status of the room.

In addition, in rooms used by individuals, the number of people information
The indoor situation is determined based on “0 people”, “1 person”, and “2Å or more”.
By displaying outside the room as ``absent,''``present,'' or ``visitor,'' others can easily and simply grasp the indoor situation. Furthermore, various environmental facilities such as air conditioning can be operated stably and effectively based on the information on the number of people.

FIG. 12 shows a specific example of a circular scanning optical system used in the number of people detection device. As shown in FIG. 2(a), a rotary plate 10 is placed at a distance JilRb from the front surface of the light receiving surface of the infrared detection element 2.
The rotary shaft 11 of the rotary plate 10 is placed on the field of view center C of the light-receiving surface of the infrared detection element 2, and the rotary plate 10 is rotated by a drive mechanism such as a motor. As shown in FIG. 12(b), a rectangular slit A having a length La and a width Da is provided in the rotary plate 10, and only the infrared rays radiated from the object surface B that pass through the slit A are infrared rays. Detection element 2
Configure it so that it is incident on the . The instantaneous visual field on the object plane is similar to the shape of the slit A, and if the distance from the rotating plate 10 to the object plane B is Ra, then the instantaneous visual field on the object plane is Lv.
, and the visual field width Dv are expressed by the following equation.

Further, in the radial direction in circular scanning, if the instantaneous field of view is the viewing angle at which the object surface B is seen, θ is expressed as in the following equation.

La θ=tan-' − Rb The above instantaneous field of view is circularly scanned around the field center C of the light-receiving surface of the infrared detection element 2 as an axis, and therefore, the total viewing angle looking into the object surface B by the circular scanning method is 2θ.

In detecting the number of people, the instantaneous visual field width Dv on the object plane is the main factor determining the number of people resolution, and in order to increase the number of people resolution, the smaller the instantaneous visual field width Dv is, the better. Therefore, although it is necessary to reduce the opening width Da of the slit A, the amount of infrared light received decreases proportionally, and a sufficient S/N ratio may not be obtained. In that case, a convex cylindrical lens is placed in the slit A to have a condensing effect in the scanning direction to obtain a predetermined instantaneous field of view width Dv and a necessary optical gain.

In Fig. 12, when a cylindrical lens is arranged in the slit A, and if the diameter of the light-receiving surface of the infrared detection element 2 is d, then the field of view of the instantaneous field on the object surface is Lv,
The visual field width Dv is expressed by the following equation.

Rh+Ra Lv=□・La Rb La Dv==□・d h As can be seen from the above equation, the instantaneous visual field width Dv is determined by selecting an appropriate Rb or d, regardless of the aperture width Da of the cylindrical lens. Instantaneous visual field width DV can be obtained. Furthermore, the optical gain can be increased by increasing the aperture width Da of the cylindrical lens.

As another means for obtaining optical gain, as shown in FIG. 13, a rotary plate 10 to which a concave cylindrical mirror M is fixed is configured to rotate about the center of field of view C of the light-receiving surface of the infrared detection element 2. It's okay. The distance from the mirror surface of the cylindrical mirror M to the light receiving surface of the infrared detection element 2 is Rb, the distance from the mirror surface of the cylindrical mirror M to the object surface B is R&, the mirror length of the cylindrical mirror M is Le+, the mirror width is Dm, When the diameter of the light-receiving surface of the infrared detection element 2 is d, the instantaneous field of view on the object surface is also Lv.

And the field width Dv is expressed by the following equation as in the case of using a cylindrical lens.

Rh + Ra Lv=□"Lea h La Dv=□・d Rb Therefore, by selecting an appropriate Rb or d, a predetermined instantaneous field of view width Dv can be obtained, and the mirror width ring of the cylindrical mirror M can be The viewing angle θ at which the instantaneous field of view looks at the object surface B in the radial direction in zero-circular scanning in which the optical gain can be increased by increasing the angle θ is given by the following equation.

L ring θ=jan″″1□ Rb large 1ヱ[L FIGS. 2(a) to 2(d) are diagrams for explaining other examples of the maximum value detection method. As described above, in the judgment unit 5 of the number of people detection device, the output waveform from the signal processing unit 4 when there is no human body within the detection area is stored in advance in the memory as reference waveform data, and the input waveform is is compared with a reference waveform in memory to determine the presence or absence of a human body and the number of people at the same time.

FIG. 2 is an explanatory diagram showing this situation, and shows the input waveform data to the judgment unit 5 (FIG. 2(b)) and the reference waveform data (second waveform data).
Comparison calculations are performed with the data in FIG. 2(a), and the results are newly used as comparison processed waveform data (FIG. 2(C)).

In the comparison processing 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. An upwardly convex waveform has one maximum point and large positive and negative slopes on both sides of the maximum point. Figure 2 (d
) is a graph showing the slope at each point, and shows that there are large positive and negative slopes before and after the maximum point. Therefore, the slope of each point is calculated, and the slope is calculated between a point with a slope larger than a preset positive slope α and a point with a slope smaller than a preset negative slope β. A point of 0 can be detected as a local maximum point.

Still another example of the local maximum point detection method will be explained based on FIGS. 3 and 4. FIG. 3 shows the temporal change of the signal including the maximum point. A filter that replaces the value at time t with the maximum value of (2i+1) data from time (t-i) to time (t+i) is defined as an interval maximum value replacement filter; ) to time (t+i), a filter that replaces the value at time t with the minimum value of (2i+ 1 ) pieces of data from time (t+i) is defined as an intra-interval minimum value replacement filter.

As shown in FIG. 4(a), when the interval minimum value replacement filter is first applied to the entire comparison processing waveform (2), the waveform (2) shown by the solid line is converted into the waveform (2) shown by the dotted line. When the maximum value replacement filter within the interval is applied to this converted waveform ■, the waveform shown by the dashed line becomes the waveform ■
is converted to

Then, by subtracting the waveform ■ shown by the dashed-dotted line from the waveform ■ shown by the solid line, a waveform as shown in Figure 4 (b) is created in which only the vicinity of the maximum point has a positive value and the rest has a value of O. can be obtained, and the local maximum points can be detected and counted from this waveform.

(Effects of the Invention) As described above, the present invention is 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 counted by counting the maximum value of the signal, the configuration is simple and inexpensive, and it has the advantage of being able to count the number of people with high accuracy while having a wide detection area.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the operation of an embodiment of the present invention, Figure 2 (a)
3 and 4 are explanatory diagrams of operation of still another embodiment of the present invention,
FIG. 5 is a block diagram showing the basic configuration of the number of people detection device according to the present invention, FIG. 6(a) is a perspective view showing a human body model for explaining the operation of the present invention, and FIG. A side view showing the arrangement of the models; Figure (c) is a plan view showing the arrangement of the above human body model; and Fig. 7 is a plan view showing a two-dimensional image of the arrangement of the above human body model seen from above. , 8th
The figure is an explanatory diagram showing the situation of circular scanning used in the present invention, FIG. 9 is an explanatory diagram showing the time change of incident energy by the same circular scanning, and FIG. 10 is a circuit configuration used in the embodiment of FIG. 1. A block diagram, FIG. 11 is an explanatory diagram of the same operation as above, FIG. 12(a) is a schematic configuration diagram showing an example of an optical system used in the embodiment same as above, FIG. 12(b) is a bottom view of the main part of same as above,
FIG. 13(a) is a schematic configuration diagram showing another example of the optical system used in the above embodiment, and FIG. 13(b) is a bottom view of the essential parts of the same. 2 is a circular 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, and 6 is an output section.

Claims (3)

[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. A number of people detection device comprising a signal processing section that converts into a necessary signal, a determining section that determines the number of people based on an output signal of the signal processing section, and an output section that outputs number of people information from the output signal of the determining section. , the scanning optical system is a circular scanning optical system that circularly scans the field of view of the infrared detection element, and the determining section is configured to detect the number of people by counting the maximum points of the output signal from the signal processing section. A number of people detection device characterized by: (2) The determination unit determines that the slope between the point where the slope of the output signal from the signal processing unit becomes a positive slope of a predetermined value or more and the point where the slope becomes a negative slope of a predetermined value or less is zero. 2. The number of people detecting device according to claim 1, wherein the device is configured to count a point as a maximum point. (3) The determination unit includes an intra-interval minimum value replacement filter that replaces the value of the output signal from the signal processing unit at each point in time with a minimum value within a predetermined interval that includes the value, and the intra-interval minimum value replacement filter. The value of the output signal of the filter at each point in time is
and an intra-interval maximum value replacement filter that replaces the value with the maximum value within a predetermined interval that includes the value, and a local maximum point is obtained by subtracting the output signal of the within-interval maximum value replacement filter from the output signal from the signal processing unit. 2. The number of people detecting device according to claim 1, wherein the device is configured to count the number of people.