JPH065304B2 - People detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an infrared ray reception type person number detection apparatus for detecting the number of persons by detecting infrared rays emitted from a human body to be detected.

(Background Art) The present inventors have already proposed a high-accuracy occupant detection device having a wide detection region with a simple and inexpensive structure. FIG. 7 shows its block diagram. This number-of-people detecting device includes an infrared detection element 2, a circular scanning optical system 1 for circularly scanning the field of view of the infrared detection element 2, a preamplifier 3 for amplifying an output signal of the infrared detection element 2, and the front portion. A signal processing unit 4 for converting the output signal of the pre-amplification unit 3 into a signal necessary for detecting the number of people.
And a determination unit 5 that determines the number of people based on the output signal of the signal processing unit 4 and an output unit 6 that outputs the number of people information from the output signal of the determination unit 5 to increase the number of people in a wide detection area. It is designed so that it can be accurately detected.

FIG. 8 shows an example of the circular scanning optical system. As shown in FIG. 3A, the rotary plate 10 is arranged at a position at a distance Rb from the front surface of the light receiving surface of the infrared detection element 2, and the rotary shaft 1 at the center of the rotary plate 10 is arranged.
1 is placed on the center c of the visual field of the light receiving surface of the infrared detecting element 2, and the rotary plate 10 is rotated by a drive mechanism such as a motor. As shown in FIG. 8 (b), the rotary plate 10 is provided with a rectangular slit A having a length La and a width Da, and only infrared rays radiated from the object surface B that have passed through the slit A are infrared rays. It is configured to enter the detection element 2. The instantaneous visual field on the object surface 2 is similar to the shape of the slit A, and when the distance from the rotating plate 10 to the object surface B is Ra, the instantaneous visual field length Lv on the object surface and the visual field width Dv are given by become that way.

Further, in the radial direction in the circular scanning, if the viewing angle at which the instantaneous field of view looks at the object plane B is θ, θ becomes as follows.

The above instantaneous visual field is the visual field center of the light receiving surface of the infrared detection element 2.
Circular scanning is performed with c as the axis, and therefore the total viewing angle for viewing 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 surface is the main factor that determines the personnel resolution, and in order to increase the personnel resolution, the instantaneous visual field width Dv should be small. Therefore, it is necessary to reduce the opening width Da of the slit A, but the amount of infrared rays received decreases in proportion to this, and in some cases a sufficient S / N ratio cannot be obtained. In that case, a cylindrical lens is arranged in the slit A portion so as to have a condensing function in the scanning direction, so as to obtain a predetermined instantaneous visual field width Dv and a required optical gain. In FIG. 6, when a convex cylindrical lens is arranged in the slit A, and the diameter of the light receiving surface of the infrared detecting element 2 is d, the visual field length Lv and the visual field width Dv of the instantaneous visual field on the object surface are given by the following equations. Like

As can be seen from the above equation, the instantaneous visual field width Dv does not depend on the aperture width Da of the cylindrical lens, but is appropriate Rd, or
A predetermined instantaneous visual field width Dv can be obtained by selecting d.
Further, the optical gain can be increased by increasing the opening width Da of the cylindrical lens.

As another means for obtaining the optical gain, as shown in FIG. 9, the rotating plate 10 having the concave cylindrical mirror M ° fixed thereon is rotated about the visual field center c of the light receiving surface of the infrared detecting element 2. It may be configured to. 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, and the mirror width is Is Dm and the light-receiving surface diameter of the infrared detecting element 2 is d, the instantaneous visual field length L on the object surface is
The v and the visual field width Dv are expressed by the following equations as in the case of using the cylindrical lens.

Therefore, by selecting an appropriate Rb or d, a predetermined instantaneous visual field width Dv can be obtained, and an optical gain can be increased by increasing the mirror width Dm of the cylindrical mirror M '. In the radial direction of circular scanning, the viewing angle θ at which the instantaneous field of view sees the object plane B is as in the case of the first embodiment, as shown in the following equation.

In addition, the total viewing angle of the object surface B by the circular scanning method is 2
θ.

In order to obtain a wide detection area, it is necessary in the circular scanning method to have a large total viewing angle for viewing the object surface B, and for that purpose, it is necessary to take a large angle θ at which the light receiving surface at the moment looks at the object surface B. is there. In order to increase θ from the equations (3) and (8), the slit length or the lens length La of the cylindrical lens, or the mirror length Lm of the cylindrical mirror M ′ may be set large. However, due to the directional sensitivity characteristic of the infrared detection element 2 with respect to the incident light, the sensitivity decreases as the angle between the incident light and the visual field center c of the light receiving surface increases, and the sensitivity becomes zero at a certain angle αmax or more. FIG. 10 shows an example of directional sensitivity characteristics of the pyroelectric element used as the infrared detection element 2. As is apparent from this figure, in the circular scanning optical system, the total viewing angle looking into the object plane is limited by the directional sensitivity characteristic of the infrared detection element 2 and cannot be sufficiently wide. There is a problem in that the sensitivity decreases so much that the sensitivity becomes nonuniform in the detection region.

(Object of the Invention) The present invention has been made in view of the above points,
An object of the invention is to provide a small-sized person detecting device having a simple and inexpensive structure and having a wide detection region with a uniform sensitivity distribution.

DISCLOSURE OF THE INVENTION FIG. 1 shows the shape of a modified saddle-shaped mirror M used in the number-of-people detecting device of the present invention. The deformed saddle mirror M is a concave surface having a continuous curvature change in one direction, and a convex surface in the other direction substantially perpendicular thereto, and the mirror M is rotationally driven with the forming direction of the convex surface as the radial direction. The field of view of the infrared detection element 2 is circularly scanned. The modified saddle mirror M has a convex shape that expands the instantaneous visual field of the light-receiving surface in the radial direction, and a concave shape has a light condensing function in the scanning direction in the circular scan.

In the scanning optical system shown in FIG. 2, the mirror surface shows a cross section taken along line XX ′ of the modified saddle-system mirror M of FIG.
Incident light entering from the point B ₁ on the object surface enters the light receiving surface S via the mirror end point M _1, and incident light entering from the point B ₂ on the object surface enters the light receiving surface S via the mirror end point M _2. Shall be incident on. The center of curvature of the convex surface of the mirror surface is O, and the normals η ₁ and η ₂ at the mirror end points M ₁ and M ₂ are the center of the visual field of the light receiving surface S.
c, that is, the angles formed with the rotation axis of the mirror M are α ₁ and α ₂ as shown in the figure. Further, the angles formed by the incident light entering the light receiving surface S via the mirror end points M ₁ and M ₂ and the center c of the field of view of the light receiving surface are θ ₁ and θ ₂ , respectively. Here, the point B ₁ on the object surface
The incident light entering the mirror end point M ₁ from the
And When parallel, the angle the incident light and the light receiving surface field center c incident from the point B ₂ on the object plane to the mirror end surfaces M ₂ beta
₂ is the radiating method instantaneous viewing angle in which the light receiving surface at an instant looks into the object plane B through the mirror M.

For each angle, there is the following relationship.

α ₁ = θ _1/2 (9) β ₂ = 2α ₂ + θ ₂ (10) From the above equation, the viewing angle (θ ₂ −θ ₁ ) on the light receiving surface S is on the object surface B via the mirror M. On the other hand, it can be seen that the viewing angle is expanded in the radial direction corresponding to the viewing angle β ₂ .
If (θ ₂ −θ ₁ ) is not relatively large, in the directional sensitivity characteristic on the light receiving surface S, there is no significant change in the directional sensitivity characteristic when the angle formed with the center c of the light receiving surface field of view is between θ ₁ and θ ₂ .
It is possible to obtain a detection area having a relatively uniform sensitivity distribution with respect to the object surface B. A normal line η _{2 at the} mirror end point M ₂ and an angle α ₂ formed with the light-receiving surface visual field center c, and an angle θ _{1 with} respect to the light-receiving surface visual field center c expected by the light-receiving surface S with respect to the mirror surface end points M ₁ , M ₂ .
By properly providing θ ₂ , a scanning optical system having a desired viewing angle can be obtained. That is, a scanning optical system having a desired viewing angle can be obtained by changing the convex curvature radius and the curvature center in the radiation direction of the mirror surface.

In FIG. 1, the modified saddle mirror M has a concave surface in the scanning direction of the mirror surface in order to have a converging function in the scanning direction, but the focal length to the light receiving surface S differs depending on each position of the mirror surface. In FIG. 3, 1 on the mirror surface
At the point Mt, Mt is an arc from the starting diameter ▲ ▼ on an arc
Let t be the point. It is assumed that infrared rays from the point P on the object surface are incident on the light receiving surface S via the point Mt, and based on the normal line ηt at the point Mt, the distance Rb from the light receiving surface to the point Mt on the mirror surface, the mirror surface The distance Ra from the point Mt on the top to the point P on the object surface is obtained. Here, the distance Rb varies depending on the position of the point Mt on the mirror surface. That is, Rb = Rb (t) ... (11). The concave surface in the scanning direction has an arc shape, and in order to collect the incident light from the point P on the object surface on the light receiving surface S, a concave surface having a focal length ft satisfying the following expression is formed at the point Mt on the mirror surface. do it.

In order to have the focal length ft, the concave surface may be formed so that the radius of curvature Rt is Rt = 2ft (13) at the point Mt on the mirror surface. On the mirror surface, the point Mt is located at the center in the width direction of the deformed saddle mirror M, the concave surface curvature center Ot is placed on the extension line of the line segment, and a concave surface may be formed so that the line segment matches the radius of curvature Rt. .

From equations (11), (12), and (13), Therefore, Rb (t) changes continuously, and the radius of curvature Rt also needs to change continuously. Further, the object plane B to be focused is a plane parallel to the horizontal plane, and the point Mt on the mirror surface is
Let R be the distance from the to the in-focus plane, and the relationship between the distance R and the distance Ra is that the angle between the line segment and the normal line ηt is θ _M , and the angle between the line segment and the light-receiving surface visual field center c is θ _F. Then, Therefore, the distance Ra also continuously changes. In this way, the concave surface of the mirror may be formed by changing the radius of curvature in consideration of the surface to be focused.

FIG. 4 shows a specific embodiment according to the present invention. The distance L ₁ from the light-receiving surface visual field center c to the mirror end surface M ₁ is 10 mm, and the distance L ₂ from the light-receiving surface S to the mirror end point M _{1 in} the visual field center direction is 4
0 mm, α ₁ = 7.018 °, α ₂ = 16.982 °,
Further, when the radius of curvature L _{3 of the} convex surface is 50 mm, the angle θ ₁ between the mirror end points M ₁ and M ₂ of the light receiving surface S and the visual field center c,
θ ₂ is θ ₁ = 14.0363 ° and θ ₂ = 36.3, respectively.
It becomes 031 °. The angle of viewing the object plane B through the mirror M is β ₂ = 70.267 °, and the total viewing angle with respect to the object plane B in the scanning optical system is 140.534 °.

FIG. 5 shows the radius of curvature of the concave surface of the deformed saddle mirror M in the scanning optical system. The position on the mirror surface is the angle t with the end surface M _{1 when} viewed from the convex curvature center O of the mirror surface. It is represented by. The radii of curvature at the end points M ₁ and M ₂ are 80.19111 mm and 61.4864 mm, respectively. The mirror width Dm is 40 mm, and the focusing position with respect to the object plane B is parallel to the horizontal plane and the mirror end surface M ₂
2m away from the bottom.

FIG. 6 shows the relationship between the angle θ formed by the light-receiving surface S and the center c of the light-receiving field of view of each mirror surface and the angle β of the object surface B through the mirror.

Here, a circuit configuration of a person number detecting device using the optical system will be described with reference to FIG. The output of the infrared detection element 2 is amplified by the preamplifier 3 and then input to a bandpass filter in the signal processor 4 to cut unstable low frequency components and high frequency components and improve the S / N ratio. Let The output of the bandpass filter is A / D converted and output to the microcomputer forming the determination unit 5. This microcomputer synchronizes the rotation of the circular scanning optical system 1 with A /
The D-converted waveform is sequentially captured. In the determination unit 5, the output waveform when the human body does not exist in the detection area is stored in the memory as reference waveform data in advance,
The input waveform is compared with the reference waveform in the memory, and the presence or absence of a human body and the number of people are simultaneously determined. In the present embodiment, the comparison calculation is performed between the input waveform data and the reference waveform data, the result is newly set as the comparison processing waveform data, the maximum value is detected in the comparison processing waveform data, and the number of the maximum values is counted as the number of people. is doing. In the comparison processed waveform data, when the number of detected persons is 0, the current input waveform data is updated as the reference waveform data and stored in the memory. By performing the comparison calculation with the input waveform data using the reference waveform data in this way, it is possible to detect the number of people with high accuracy without being affected by the environmental change in the detection region.
The output unit 6 is configured to display the number-of-people information based on the number-of-people information provided from the determination unit 5. In a meeting room or the like, the number of people or the degree of congestion are displayed outside the room so that other people can understand the indoor usage situation outside the room. In addition, in a room used by an individual, based on the number information "0 person", "1 person", "2 or more persons", the indoor status is set as "absent", "present", or "guest" By displaying in, the other person can easily and simply grasp the indoor situation. Furthermore, based on the number of people information, various environmental facilities such as air conditioning can be operated stably and effectively.

(Effect of the invention) As described above, the present invention is an infrared ray receiving type person detecting device for detecting the number of persons by detecting infrared rays emitted from a human body to be detected, in which a concave surface having a continuous curvature change in one direction, By providing a deformed saddle mirror having a convex surface in another direction substantially perpendicular thereto, and by rotating the deformed saddle mirror with the forming direction of the convex surface of the deformed saddle mirror as a radial direction, the infrared detection element Since the field of view is scanned circularly, there is an effect that the size can be easily reduced, the structure can be configured easily and inexpensively, and a uniform sensitivity distribution can be obtained over a wide detection region.

[Brief description of drawings]

FIG. 1 is a perspective view of an essential part of an optical system used in the number-of-people detecting apparatus according to the present invention, FIGS. 2 to 4 are explanatory diagrams of the operation of the optical system of the above, and FIGS. 5 and 6 are optical systems of the same. FIG. 7 is a block diagram of a conventional example, FIG. 8 (a) is a schematic configuration diagram of an optical system used in the conventional example, FIG.
Figure (a) is a schematic configuration diagram of an optical system that uses another for the conventional example,
(b) is a bottom view of the main part of the above, and FIG. 10 is a directional characteristic diagram of the infrared detecting element used in the same. Reference numeral 1 is a circular scanning optical system, 2 is an infrared detection element, 3 is a preamplifier, 4 is a signal processing section, 5 is a judgment section, 6 is an output section, and M is a deformed saddle mirror.

Front page continued (72) Inventor Takashi Horii 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. (72) Hiroshi Matsuda, 1048, Kadoma, Kadoma, Osaka Prefecture (72) Inventor, Princess Hime Hidekazu Sawa 1048 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd.

Claims (1)

[Claims] 1. An infrared detecting element, a scanning optical system for scanning a field of view of the infrared detecting element, a preamplifier for amplifying an output signal of the infrared detecting element, and an output signal of the preamplifier for the number of persons. Number of people detection including a signal processing unit for converting into a signal necessary for detection, a determination unit for determining the number of people based on the output signal of the signal processing unit, and an output unit for outputting the number of people information from the output signal of the determination unit In the apparatus, the scanning optical system is provided with a deformed saddle mirror having a concave surface having a continuous curvature change in one direction and a convex surface in the other direction substantially perpendicular thereto, and forming the convex surface of the deformed saddle mirror. A people detection apparatus, which is an optical system for circularly scanning the field of view of the infrared detection element by rotationally driving the deformed saddle mirror with the direction as a radial direction.