JPS63134986A - Person number detector - Google Patents

Abstract

PURPOSE:To obtain a uniform sensitivity distribution over a wide detection area by providing a first mirror for scanning circularly a visual field of an infrared ray detecting element, and a second mirror for reflecting again infrared rays reflected by the first mirror, and making it incident on the infrared ray detecting element. CONSTITUTION:It is supposed that the photodetecting surface S of an infrared ray detecting element is placed in parallel to the floor surface, and the visual field center (c) of the photodetecting surface S is vertical to the horizontal plane. In a radial direction end part of an instantaneous visual field, incident light B1 is made incident on the photodetecting surface S through an end point M3 of a mirror MB, and an end point M1 of a mirror MA, and incident light B2 is made incident on the photodetecting surface S through an end point M4 of the mirror MB, and an end point M2 of the mirror MA. In a directional sensitivity characteristic of the infrared ray detecting element 2, when an angle made by the incident light when the sensitivity becomes zero, and the visual field center (c) of the photodetecting surface is denoted as alphamax, an angle 2theta of the instantaneous visual field in which the photodetecting surface S views an object surface can be taken up to the maximum 2alphamax.

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. Figure 4 shows its configuration. 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.

An example of a circular scanning optical system is shown in FIG. 5. As shown in FIG.
The rotary plate 10 is placed at a position, 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. 5(b), the rotary plate lO has a length La,
A rectangular slit A with a width Da is provided, and only the infrared rays radiated from the object surface B that pass through the slit A are
The configuration is such that the infrared rays are incident on the infrared detection element 2. The instantaneous visual field on the object plane is similar to the shape of the slit A, and if the distance from the rotary plate 10 to the object plane B is Ra, then the instantaneous visual field length Lv and visual field width DV on the object plane are expressed by the following equation. It becomes like this.

Rb+Ra Lv=□・La...(1)Rb Rb+Ra Dv=□・Da...(2)Rb Also, in the radial direction in circular scanning, the viewing angle at which the instantaneous visual field looks at the object surface B is θ. Then, θ becomes as shown in the following equation.

Ra θ=jan-'□ ... (3) 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, and therefore the entire field of view looking into the object surface B by the circular scanning method. The angle 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. 5, when a cylindrical lens is placed in the slit A, and the diameter of the light-receiving surface of the infrared detection element 2 is d, the field of view of the instantaneous field of view on the object surface is Lv, and the field width is D.
v is as shown in the following equation.

Rb + Ra LV=□・La...(4)h Ra Dv=□・d...(5)Rb As can be seen from the above equation, the instantaneous visual field width Dv is independent of the aperture width Da of the cylindrical lens. , Rb, or d can be selected to obtain a predetermined instantaneous visual field width DV. Furthermore, the optical gain can be increased by increasing the aperture width Da of the cylindrical lens.

Further, as another means for obtaining optical gain, as shown in FIG. 6, a rotary plate 10 to which a concave cylindrical mirror M is fixed is rotated about the center of field of view C of the light-receiving surface of the infrared detection element 2. The distance from the mirror surface of the cylindrical mirror M to the light receiving surface of the infrared detection element 2 may be Rb, the distance from the mirror surface of the cylindrical mirror M to the object surface B may be -Ra, and the cylindrical mirror M
When the mirror length of is L+*, the mirror width is D+s, and the diameter of the light-receiving surface of the infrared detection element 2 is d, the instantaneous field of view length L on the object surface is
v and the visual field width Dv are expressed by the following equations as in the case of using a cylindrical lens.

Rb + Ra L, v=□・L−...(6) Rb Ra Dv=□・d...(7)h Therefore, by selecting an appropriate Rb or d, a predetermined instantaneous visual field width can be obtained. Dv can be obtained and the optical gain can be increased by increasing the mirror width of the cylindrical mirror M. In the radial direction in 0 circular scanning, the viewing angle θ at which the instantaneous field of view looks at the object surface B is determined by Similarly to Example 1, the following equation is obtained.

L- θ==tan-J
becomes θ.

In order to obtain a wide detection area, in the circular scanning method,
It is necessary to take a large total viewing angle when looking at object surface B, and to do so, the angle θ at which the light-receiving surface looks at object surface B at an instant must be increased.
It is necessary to take a large value.

From equations (3) and (8), in order to increase θ, the slit length or the lens length of the cylindrical lens L
m, or the mirror length Lm of the cylindrical mirror M may be increased.6However, due to the directional sensitivity characteristics of the infrared detection element 2 to the incident light, as the angle between the incident light and the center of field of view of the light-receiving surface C increases, the sensitivity decreases. decreases,
Above a certain angle αmax, the sensitivity becomes zero. An example of the directional sensitivity characteristics of the pyroelectric element used as the infrared detecting element 2 is shown in Fig. 7.As is clear from this figure, in the circular scanning optical system, the total viewing angle looking onto the object surface is the same as that of the infrared detecting element 2. It is limited by the directional sensitivity characteristics of the sensor, and cannot be made sufficiently wide.Furthermore, in the field of view, the sensitivity in the peripheral area decreases, resulting in non-uniformity in sensitivity within the detection area.

(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 has a simple and inexpensive configuration and has a uniform sensitivity distribution over a wide detection area.

(Disclosure of the Invention) Fig. 1 is a schematic configuration diagram when viewed from the side of a circular scanning optical system using two reflecting mirrors MA+MB used in the number of people detection device according to the present invention.
The light-receiving surface S of is arranged parallel to a horizontal plane, that is, the floor surface, and the field of view center C of the light-receiving surface S is perpendicular to the horizontal surface. At the radial end of the instantaneous field of view, the incident light B is reflected by the mirror M,
through the end point M1 of the mirror MA and the end point M of the mirror MA.
The incident light B2 enters the light receiving surface S via the end point M1 of the mirror MB and the end point M2 of the mirror MA. Incident light B
, is incident on the mirror M perpendicularly from the horizontal plane, then the angle that the incident light B2 makes with the field of view center C1 of the light-receiving surface S, that is, the rotation axis of the mirrors MA and MB, is the angle that the incident light B2 makes with the light-receiving surface in the circular scanning optical system of the present invention. S is the instantaneous viewing angle looking into the object surface. The effective viewing angle of the light-receiving surface S is determined by the mirrors MA, and the mirrors are arranged below the light-receiving surface S so that each mirror has an effective viewing angle of an angle θ from the viewing center C.

At this time, the angle that the incident light B2 makes with the visual field center of the light receiving surface S is 2
θ, and the instantaneous viewing angle at which the light-receiving surface S looks at the object surface is 2θ. Assuming that the incident light B2 is reflected by the end point M4 of the mirror MB and the optical path when it enters the end point M2 of the mirror MA is parallel to the horizontal plane, the angles α and β made by the mirror MA and the mirror MB with the horizontal plane are expressed by the following formula % Formula % In the directional sensitivity characteristic of the infrared detection element 2, the angle between the incident light and the center of field of view of the light-receiving surface C when the sensitivity becomes zero is αw
ax, the angle 2θ of the instantaneous field of view at which the light-receiving surface S looks at the object surface by the optical system can be up to 2αwax. Furthermore, by using a range in which the directional sensitivity characteristics of the infrared detection element 2 are relatively uniform, a wide detection area having a relatively uniform sensitivity distribution can be obtained.

In a circular scanning optical system, in order to improve human body resolution, it is necessary to reduce the instantaneous field of view width, but if mirror MA is a concave cylindrical mirror, in order to increase the focal length, the circular scanning optical system must become larger. Therefore, mirror MA is a plane mirror, and mirror M is a concave cylindrical mirror. By using a concave cylindrical mirror, a condensing effect can be obtained in the scanning direction. This circular scanning optical system is equivalently shown in Fig. 2, and in Fig. 2, the equivalent light-receiving surface is S'' If the distance from the equivalent light-receiving surface S' to mirror M is Rb, the distance from mirror MB to the in-focus surface is Ra, and the focal length of mirror MB is f, then there is the following relationship. The surface is parallel to the surface of the mirror M and makes an angle β with the horizontal plane.

The light condensing situation by the optical system is shown in FIG.

Let the width of the concave cylindrical mirror MB be L, and the width on the plane mirror MA of the beam of light condensed via the end point M of the concave cylindrical mirror MA! 3. If the width of the ray bundle condensed through the end point M of the concave cylindrical mirror M on the plane mirror MB is 12, then 0 In this example, L<12, so it is a single plane mirror. MA is 1 Ru Naguto i, B1. It suffices if it is a rectangle with length M and length M2.

Here, the circuit configuration of the number of people detection device using the optical system will be explained based on FIG. 4. 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 forming 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 judgment unit 5, the output waveform of thirst in which no human body is 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 judged at the same time. In this example, three comparison operations are performed between input waveform data and reference waveform data, the results are 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, if the detected number of people is 0, the current input waveform data is updated as snowy weather 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 section 6 displays the number of people information based on the number of people information given from the judgment section 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 2Å”, the indoor situation is determined as “absent person”.
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 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. and a second mirror that re-reflects the infrared rays reflected by the first mirror and makes them enter the infrared detecting element, the directional sensitivity characteristics of the infrared detecting element can be effectively used, and a wide range of This has the advantage that a uniform latitude distribution can be obtained over the detection area, and that it can be constructed simply and at low cost.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of an optical system used in the people detection device according to the present invention, Figs. 2 and 3 are explanatory diagrams of the operation of the same optical system, Fig. 4 is a block diagram of a conventional example, and Fig. 5 (a) is a schematic configuration diagram of the optical system used in the conventional example, FIG. 6 (b) is a bottom view of the main parts of the same as above, and FIG. (b) is a bottom view of the essential parts of the same as above, and FIG. 7 is a directivity characteristic diagram of the infrared detecting element used in the above. 1 is a circular scanning system, 2 is an infrared camera, 3 is a preamplifier, 4 is a signal processing function, 5 is a judgment unit, 6 is an output unit, MA
,M, is a mirror.

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. 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 includes a first mirror that circularly scans the field of view of the infrared detection element, and a second mirror that reflects the infrared rays reflected by the first mirror again and makes them enter the infrared detection element. A number of people detection device characterized by comprising: