JPS63134983A - Person number detector - Google Patents

Abstract

PURPOSE:To reduce a photodetecting sensitivity difference in infrared rays due to a distance, and to reduce a level difference in a human body detecting signal due to the distance, by rotating a visual field surface formed by a slit whose opening width is widened as it is placed away from the rotation center. CONSTITUTION:A circular scanning optical system 1 is provided with a slit X whose opening width is widened as it is placed away from the rotation center, and by rotating a visual field surface formed by this slit X, a visual field of an infrared ray detecting element 2 is scanned circularly. When this slit X is placed in front of a cylindrical mirror M, as for a level of a signal obtained by the infrared ray detecting element 2, the level becomes low in the near part, and the level becomes high in the distant part. In such a way, a photodetecting sensitivity difference in infrared rays due to the distance in a detection area can be reduced, and the number of persons can be measured exactly.

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) The present inventors have already proposed a highly accurate number of people detection device that has a simple and inexpensive configuration and a wide detection area. FIG. 7 shows its configuration diagram. 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. The output section 6 outputs information on the number of people in a wide range of detection areas, making it possible to detect the number of people within a wide detection area with high precision.

First, the circular scanning method will be explained. When the human body to be detected is viewed from above, it is as shown in FIG. This has a height of 170 cm and a width of 50 cm as shown in Figure 8(a).
Using a rectangular parallelepiped with a depth of 20 CTI as an upright human body model, four human body models 'm, i to TL4 are placed at the vertices of a square with a side of 3 m, as shown in Fig. 8(b) and (c). This is a two-dimensional image projected onto a plane parallel to the floor surface U at a point 3 m above the floor surface U by the human body model desks 1 to TrL4. As is clear from the figure, the human body seen from above is
Except when placed at the center C of the visual field, the side of the human body is also viewed, resulting in an image extending in the radial direction from the center C of the visual field.

Further, as the position of the human body moves away from the visual field center C, the human body image becomes more elongated in the radial direction. Considering the above points,
It can be seen that human bodies can be effectively and efficiently detected, identified, and counted by providing a rectangular slit-shaped viewing surface and using a circular scanning method in which the viewing surface is rotated around its end point.

FIG. 10 shows an example of a circular scanning optical system. As shown in the figure (,), distance R from the front of the light receiving surface of the infrared detection element
The rotary plate 10 is placed at position b, the rotating 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. 10(b), the rotating plate 10 has a length L.
A and a rectangular slit A having a width Da are provided so that only the infrared rays radiated from the object surface B that pass through the slit A enter the infrared detecting element 2. The instantaneous field of view on the object plane has the same shape as the slit A, and if the distance from the rotary plate 10 to the object plane B is Ra, then the instantaneous field of view length Lv and the field width Dv on the object plane are calculated by the following formula. become that way.

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.

The above-mentioned instantaneous field of view is circularly scanned with 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 FIG. 10, if a convex cylindrical lens is provided at the slit A, a desired optical gain can be obtained.

Furthermore, as another means for obtaining optical gain, as shown in FIG. There are also examples of configuration. 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 Ra, the mirror length of the cylindrical mirror M is Lm, the mirror width is Da, When the diameter of the light-receiving surface of the infrared detection element 2 is d, the instantaneous field of view length Lv on the object surface is
, and the visual field width Dv are expressed by the following equation.

Therefore, by selecting an appropriate Rb or d, a predetermined instantaneous field of view width Dv can be obtained, and the optical gain can be increased by increasing the mirror width R of the cylindrical mirror M. In the radial direction during scanning, the viewing angle θ at which the instantaneous visual field looks at the object surface B is expressed by the following equation, and the total viewing angle is 2θ.

In the optical system of this device, the greater the distance between the detected human body and the human body detection device, the lower the infrared detection sensitivity, so the signal level obtained from a nearby human body and a distant human body changes greatly, and the signal processing In extreme cases, small signals may not be detected.

For example, as shown in FIG. 11, a person Tn, A, aa standing near the detection device has his or her entire body within its field of view, whereas a person standing far away has the entire body within its field of view. TrLc is about 1/2 of the whole body, and a person standing further away, 'rrLD, is about 11% of the whole body.
Only about 500 yen can be seen within the field of view, so the signal level from a long distance becomes extremely low.

In addition, although the entire body of humans nA and ne is within the field of view, even so, compared to the level of infrared rays emitted from the human A at a close distance, the level of infrared rays received from the human IrrL at a far distance is There has been a problem in that the level of received infrared rays emitted is low.

Therefore, it is desirable to make the output obtained from the human body within the detection area as uniform as possible, but if you try to achieve this with a rectangular aperture, the field of view of the infrared detection element 2 will be considerably larger than the required detection area. It becomes necessary to make the mirror wider, and for this purpose the length of the mirror M must be increased.
There is a problem that the optical system becomes large.

(Object of the invention) The present invention has been made in view of the above points, and
The purpose is to provide a number of people detection device that can reduce the difference in infrared reception sensitivity depending on the distance within the detection area and can reliably count the number of people.

(Disclosure of the Invention) In the number of people detection device according to the present invention, as shown in FIG. 1, the circular scanning optical system 1 is provided with a slit X whose aperture width becomes wider as the distance from the rotation center increases. By rotating the field of view formed by this slit X, the field of view of the infrared detection element 2 is made to scan in a circular manner. When this slit Compared to the case of the solid line in the figure used, the level is lower in the vicinity, and the level is higher in the distance. This makes it possible to reduce the difference in infrared light reception sensitivity depending on the distance within the detection area, making it possible to accurately count the number of people.

Hereinafter, the principle of the present invention will be explained while comparing it with a conventional example.

First, it is assumed that the power radiated from a microscopic surface flds of a certain object is PT, and the distribution of power emitted from this surface is based on the cosine law. @ Let ψ be the angle between the normal direction of the small surface WIdS and the direction in which the detection device is viewed from the small area dS. At this time, the diameter of the infrared detection element 2 is d, the mirror width of the cylindrical mirror M is D, the distance between the infrared detection element 2 and the mirror M is Rb, and the minute area from the mirror is dS.
If the distance to the infrared detection element 2 is Ra, the power dP received by the infrared detection element 2 from the minute area dS is approximately expressed by the following equation.

Considering the directivity characteristics of the infrared detection element 2, the sensitivity in the normal direction of the light-receiving surface follows the habocosine law, so the output signal dS0 of the element due to the incident power from a point tilted by θ from the normal direction is given by the following formula: become that way.

Based on this formula, the human body is considered to be a rectangular parallelepiped as shown in FIG. 8, and the results of calculating the element output at each distance are shown in a graph in FIG. At this time, the shape of the cylindrical mirror M shown in FIG. 11(b) is used without a slit.

Fourth, assume that a pyroelectric element is used as the infrared detection element 2, and two people 'rrLA, ms are standing as shown in the figure. In Figure 4, Q is the rotation direction of the field of view,
Fo indicates the entire effective field of view of the detection device.

In this case, the incident power from the first person 'rrL8 is large as shown in FIG. 5(a), but the incident power from the second person 'a
The incident power from B is small as shown in Fig. 5(b), so the signal obtained by the first person 'm, A is large as shown in Fig. 5(e), and the signal obtained by the second person The signal obtained by 'aB' becomes small as shown in FIG. 5(d). Therefore, the detection output of the infrared detection element 2 becomes as shown in FIG. 5(e), and since the signal corresponding to the first person aA is too large, the signal corresponding to the second person 'Is is There are problems such as the mountain being hidden or the mountain becoming smaller, it is impossible to find the maximum value of the mountain in order to detect the number of people, and there are problems such as which level or higher the maximum value should be regarded as a human body.

Therefore, in the present invention, a trumpet-shaped slit X as shown in FIG. ing. In FIG. 1, the shaded portion is a light-shielding portion, and the other portions are light-transmitting portions. When this trumpet-shaped slit It gets expensive. In Figure 2,
The horizontal axis shows the distance from the detection device, the vertical axis shows the level of the signal obtained by the infrared detection element 2, and the solid line shows the characteristics of a PA using a rectangular slit as a comparative example.

In the case where the trumpet-shaped slit X is added, it is assumed that human breasts A and na stand at the position shown in FIG. 4. In this case, the incident power from the first person 'aA decreases as shown by the solid line in FIG.
as shown by the solid line. Therefore, the signal obtained by the first person TrLA becomes small as shown by the solid line in FIG. 3(c), and the signal obtained by the second person 'la becomes small as shown by the solid line in FIG. 3(d). growing. Therefore, the detection output of the infrared detection element 2 is
As shown by the solid line in Figure (e), signals that were hidden when a rectangular slit was used can now be fully detected. Furthermore, since the difference between the field of view seen from the infrared detection element 2 and the detection area is narrowed, the influence of noise from outside the detection area is reduced. In addition, Fig. 3 (a) to (e
), the broken line shows the characteristics when a rectangular slit having the same length as the trumpet-shaped slit X is used as a comparative example.

Here, the circuit configuration of a device for detecting the number of people using the optical system will be explained based on FIG. 7. The output of the infrared detection element 2 is amplified by the preamplifier 3 and then input to the bandpass filter in the signal processing unit 4, which cuts unstable low frequency components and unnecessary high frequency components, and improves the S/N. improve the ratio. The output of the bandpass filter is A/D converted and output to the microcomputer that constitutes the judgment section 5. This microcomputer sequentially captures A/D converted waveforms every rotation in synchronization with the rotation of the circular scanning optical system 1.

In the determination unit 5, the output waveform when a human body is not present in the detection area is stored in memory as reference waveform data, 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 are determined simultaneously.

In this example, a comparison operation is performed between input waveform data and reference waveform data, the result is used as new comparison processing waveform data, local maximum values are detected in the comparison processing waveform data, and the number of local maximum values is counted as the number of people. are doing. In the comparison processing waveform data, when the detected number of people is O, the current input waveform data is updated as reference waveform data and stored in the memory. By performing comparison calculations with the input waveform data using the reference waveform data in this way, it is possible to detect the number of people with high precision without being affected by environmental changes within the detection area. The output unit 6 is designed to display the number of people information based on the number of people information given by the determination unit 5. 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 is "0 people".

Based on “one person” and “more than 2 Å”, the indoor situation is determined as follows:
By displaying outside the room as “in room” or “visitor”,
Others can easily and simply understand 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.

(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. By rotating the field of view that is formed, the field of view of the infrared detection element is circularly scanned, and the amount of infrared rays received through the slit increases as the distance from the center of rotation increases. Since the difference in light reception sensitivity can be reduced and the difference in the level of the human body detection signal depending on the distance can be reduced, there is an effect that the number of people can be counted accurately.

[Brief explanation of the drawing]

Fig. 1 is a front view of the slit used in the number of people detection device according to the present invention, Figs. 2 to 4 are explanatory diagrams of the same operation as above, Figs. 5 and 6 are explanatory diagrams of the operation of the conventional example, and Fig. 7 8 is a block diagram of the conventional example, FIG. 8(a) is a perspective view showing a human body model for explaining the operation of the above, FIG. ) is a plan view showing the arrangement of the human body model as above, FIG. 9 is a plan view showing a two-dimensional image of the arrangement of the human body model as seen from above, and
Figure (a) is a schematic diagram of the optical system used in the conventional example;
1]) is a bottom view of the main parts of the same as above, FIG. 11(a) is a schematic configuration diagram of an optical system used in another conventional example, and FIG. 11(b) is a bottom view of the main parts of the same. 1 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 or slit.

Claims (1)

[Claims] (1) An infrared detection element, a circular scanning optical system that circularly 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 A number of people detection unit that includes a signal processing unit that converts into a signal necessary for detection, 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. In the apparatus, the circular scanning optical system is an optical system that circularly scans the field of view of the infrared detection element by rotating a field of view formed by a slit whose aperture width becomes wider as the distance from the center of rotation increases. A device to detect the number of people.