JPH06100660B2 - 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 detection 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.

In the determination unit 5 of this number-of-people detector, the output waveform from the signal processing unit 4 when the human body does not exist in the detection area is stored in the memory as reference waveform data in advance, and the input waveform is stored in the memory. The presence / absence of a human body and the number of persons are simultaneously determined by comparison with the reference waveform. FIG. 4 is an explanatory diagram showing this state, in which the comparison calculation is performed between the input waveform data (FIG. 4 (b)) and the reference waveform data (FIG. 4 (a)) to the determination unit 5, and the result is shown. Is newly used as comparison processing waveform data (FIG. 4 (c)). In the comparison processing waveform, the voltage level is almost zero in the portion where the human body does not exist, and a convex waveform appears in the portion where the human body exists. Maximum points are detected for this comparison processed waveform, and the number of maximum values is counted as the number of people. 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.

In this way, the reference waveform data when the human body to be detected does not exist is stored in advance as the background data and the comparison calculation with the input waveform data is performed, so that the number of people can be detected without being affected by the environmental change in the detection area. It can be performed. However, in this method, since the reference waveform cannot be updated unless the number of detected persons becomes 0, the same reference waveform may be used for a long time without being updated. In this case, over time, the ambient environment of the person detection device changes significantly due to changes in room temperature, changes in the amount of direct sunlight, turning on and off of air conditioning, etc. A convex waveform may appear even in a nonexistent portion, which causes erroneous detection.

As described above, in the conventional example, when the human body does not exist, the reference waveform is updated by using the input waveform as the reference waveform, and the influence of the environmental change can be removed. If the detection continues, the reference waveform cannot be updated, and there is a problem that the influence of the environmental change in the detection area cannot be removed.

(Object of the Invention) The present invention has been made in view of the above points,
It is an object of the present invention to provide a number-of-people detection device capable of highly accurately detecting the number of people by removing the influence of environmental changes in the detection area.

DISCLOSURE OF THE INVENTION In the number-of-people detection device according to the present invention, as shown in FIG. 2, 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 the output signal of the infrared detection element 2, a signal processor 4 for converting the output signal of the preamplifier 3 into a signal necessary for detecting the number of people, and an output signal of the signal processor 4. In the number-of-people detecting device, which comprises a judging section 5 for judging the number of people based on the above, and an output section 6 for outputting the number of people information from the output signal of the judging section 5, the judging section 5 performs signal processing when there is no human body to be detected. An input waveform from the unit 4 is stored in advance as a reference waveform, the number of persons is determined based on the difference between the input waveform and the reference waveform, and at least a portion of the reference waveform other than a portion corresponding to the detected human body is detected. To update parts sequentially It is composed of components.

FIG. 2 is a diagram showing a schematic configuration of the number-of-people detecting device according to one embodiment of the present invention. 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, an inexpensive pyroelectric element that does not require cooling is used. Since this pyroelectric element contains a lot of low frequency components as background noise, the band-pass filter 41 cuts unstable low frequency components and also cuts unnecessary high frequency components, thereby improving the S / N ratio. . The output of the bandpass filter 41 is input to the A / D converter 42 and is output by the A / D converter 42.
It is A / D converted and output to the microcomputer 51 that constitutes the determination unit 5. The motor drive unit 12 operates according to a control signal from the microcomputer 51, and drives and stops the motor as necessary. In the rotation cycle detector 13,
A periodic signal is output to the microcomputer 51 for each rotation in synchronization with the scanning of the circular scanning optical system. Microcomputer 51, based on the synchronization signal from the rotation cycle detection unit 13,
The data from the A / D converter 42 is sequentially taken in every one rotation.

FIG. 3 is a flow chart for explaining the operation of the judgment unit 5 in this embodiment. From the A / D converter 42 in the signal processing unit 4, a predetermined number of data for one cycle of the circular scanning optical system 1 are sent at equal angular intervals and are stored in the input buffer of the microcomputer 51. A microcomputer is generated by the synchronization signal from the rotation cycle detector 13.
51 interrupted, first, the microcomputer
Reference numeral 51 fetches the input waveform data accumulated in the input buffer for one period of the scanning system. In the microcomputer 51, the input waveform when a human body does not exist in the detection area is stored in the memory as reference waveform data in advance. The microcomputer 51 reads this previously stored reference waveform from the memory and subtracts it from the input waveform. As a result, a comparison processing waveform is generated. The maximum point is detected and counted from this comparison processing waveform, and the number of people information is output. When the number of detected persons is 0, the reference waveform is entirely updated by the input waveform. When the number of people to be detected is one or more, the reference waveform is divided into a portion where the detected human body exists and a portion where the detected human body does not exist, and updated by the method described below.

FIG. 1 is an explanatory view showing a method of updating a reference waveform in the present embodiment. FIG. 1A shows a reference waveform X stored in advance in the judging section 5, and FIG. The input waveform Y is shown, FIG. 6C shows the comparison processing waveform Z obtained by subtracting the reference waveform Y from the input waveform X, and FIG. 7D shows the reference waveform X after updating. In each of these waveforms, the time T ₀ through T ₁ part _{X A, Y A, Z A} , X C corresponds to the non-existent parts of the body, the time T ₁ through T ₂ parts X _B, Y _B, Z _B and X _D correspond to the part where the human body exists. In order to detect the portion where the human body is present, for example, a portion of the comparison processing waveform Z that has a maximum value whose absolute value is equal to or higher than a predetermined level and has a height corresponding to the human body may be searched.

Now, it is assumed that the portion Z _B in the comparison processing waveform Z is determined to be the portion where the human body exists. In the comparison processing waveform Z, even in the portion Z _A where no human body exists, it is not exactly zero due to the influence of environmental changes. At this time, first, the input waveform Y _{A of the} portion where the human body does not exist is newly set as the reference waveform X _C. Furthermore, the average change in the part Z _A where the human body does not exist is obtained. That is, the average value a of the Z _A part is Is. The value a at each point of the portion of the X _B in the reference waveform by adding the average variation is updated as a new reference waveform X _D.

As described above, the feature of the present invention is that the reference waveform X is divided into the portion X _A where the human body does not exist and the portion X _B where the human body exists, and the input waveform Y at that time is applied to the portion X _A where the human body does not exist. _A
To update as reference waveform X _C. As a result, the reference waveform can be constantly updated at least in the portion where the human body does not exist. Further, regarding the portion X _{B where} the human body exists, it is possible to constantly update the reference waveform by estimating the change due to the environment and adding the average change amount a to the current reference waveform X _B.

The output unit 6 displays the number of people information based on the number of people information provided from the microcomputer 51. 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 persons or more”, the indoor status is set as “absent”, “present room”, “visitor” and outdoors. 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.

FIG. 5 shows an example of a circular scanning optical system used in the above-mentioned number of people detecting device. 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,
The rotating shaft 11 at the center of the rotating plate 10 is arranged on the visual field center c of the light receiving surface of the infrared detecting element 2, and the rotating plate 10 is rotated by a drive mechanism such as a motor. As shown in FIG. 5 (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 enter the infrared detection element 2. The instantaneous visual field on the object surface 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 Like

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 circularly scanned around the visual field center c of the light receiving surface of the infrared detecting element 2, and therefore, the total visual field angle for viewing the object plane B by the circular scanning method is 2θ.

When detecting the number of people, the instantaneous visual field width Dv on the object surface is the main factor that determines the person resolution, and in order to increase the number of people 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 convex cylindrical lens is arranged in the slit A portion so as to have a condensing action in the scanning direction to obtain a predetermined instantaneous visual field width Dv and a required optical gain. In FIG. 5, when a cylindrical lens is arranged in the slit A, and the diameter of the light receiving surface of the infrared detection 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 as follows. become.

As can be seen from the above expression, the instantaneous visual field width Dv can be obtained as a predetermined instantaneous visual field width Dv by selecting an appropriate Rb or d regardless of the aperture width Da of the cylindrical lens. 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 the embodiment of FIG. 6, the rotating plate 10 to which the concave cylindrical mirror M is fixed 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, the mirror width is Dm, Assuming that the light receiving surface diameter of the infrared detecting element 2 is d, the instantaneous visual field length Lv and the visual field width Dv on the object surface
Is similar to the case where a cylindrical lens is used, as in the following equation.

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 in circular scanning, the viewing angle θ at which the instantaneous field of view sees the object surface B is
It becomes like the following formula.

By using such a circular scanning optical system, one input waveform can be obtained for each rotation, and thus the presence or absence of human bodies and the number of human bodies can be easily detected by the determination unit 5 having the above-described configuration.

(Effects of the Invention) As described above, the present invention is obtained by circularly scanning the field of view of an infrared detection element in an infrared-reception-type people detection device that detects infrared rays emitted from a detected human body to detect the number of people. The number of people is determined by comparing the input waveform with an input waveform stored in advance as a reference waveform when there is no detected human body, and at least the portion of the reference waveform other than the portion corresponding to the detected human body is updated sequentially. Therefore, the reference waveform is updated even when the human body is present in the detection area, and the effect of being able to detect the number of people with high accuracy by removing the influence of the environmental change in the detection area. There is.

[Brief description of drawings]

FIG. 1 is an operation explanatory view of an embodiment of the present invention, FIG. 2 is a block diagram showing a schematic configuration of the embodiment described above, FIG. 3 is a flow chart showing processing of a judgment unit used in the same, FIG. FIGS. 5A to 5C are diagrams for explaining the operation of the determination unit of the above, FIG. 5A is a schematic configuration diagram of an optical system used in the embodiment of the above, and FIG. FIG. 6 (a) is a schematic configuration diagram of an optical system used in another embodiment of the present invention, FIG. 6 (b) is a bottom view of an essential part of the same, and FIG. 7 is a block diagram showing a schematic configuration of a conventional example. . Reference numeral 1 is a circular scanning optical system, 2 is an infrared detection element, 3 is a preamplifier, 4 is a signal processor, 5 is a judgment section, and 6 is an output section.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Horii 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (72) Hiroshi Matsuda, 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Works, Ltd. (72) Inventor Shinji Kiribata 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd.

Claims (1)

[Claims] 1. An infrared detecting element, a circular scanning optical system for circularly 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. A signal processing unit that converts the number of people into a signal necessary for detecting the number of people, 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 the number of people information from the output signal of the determination unit. In the number-of-people detection device, the determination unit is configured to store in advance the input waveform from the signal processing unit when the human body to be detected does not exist as a reference waveform, and determine the number of people based on the difference between the input waveform and the reference waveform. Further, the number-of-persons detecting device is configured to sequentially update at least a portion other than a portion corresponding to the detected human body in the reference waveform.