JPS63134989A - Person number detector - Google Patents

Abstract

PURPOSE:To eliminate influence of an environmental variation in a detection area, and to detect the number of persons with high accuracy by deciding the number of persons by comparing an input waveform obtained by scanning circularly a visual field of an infrared ray detecting element, with a reference waveform when the human body to be detected does not exist, and also, updating successively the reference waveform. CONSTITUTION:A visual field of an infrared ray detected element 2 is scanned circularly, and an output of this element 2 is amplified 3 and led to a band pass filter 41, and thereafter, A/D-converted 42, and outputted to a microcomputer 51 for constituting a deciding part 5. The deciding part 5 stores in advance as a reference waveform an input waveform from a signal processing part 4 when the human body to be detected does not exist, decides the number of persons based on a difference between the input waveform and the reference waveform and also, updates successively other parts than the part corresponding to at least the human body to be detected in the reference waveform.

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. This device consists of an output unit 6 that outputs information on the number of people, and can detect the number of people within a wide detection area with high accuracy.

In the determination unit 5 of this 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 the memory as reference waveform data, and the input waveform is stored in the memory as reference waveform data. The presence or absence of a human body and the number of people are determined at the same time. FIG. 4 is an explanatory diagram showing this situation, in which a comparison operation is performed between the input waveform data to the judgment unit 5 (FIG. 4(b)) and the reference waveform data (FIG. 4(a)), and the result is Compare newly processed waveform data (
In the comparison processing waveform shown in FIG. 4(C), 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.

Local maximum points are detected for this comparison processed waveform, and the number of local maximum values is counted as the number of people. 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.

In this way, the reference waveform data when there is no human body to be detected is stored in advance as background data, and by performing comparison calculations with the input waveform data, it is possible to detect the number of people without being affected by environmental changes within the detection area. It can be performed. However, in this method, the reference waveform cannot be updated unless the number of detected people becomes 0, so the same reference waveform may be used for a long time without being updated. In this case, as time passes, the surrounding environment of the people detection device changes significantly due to factors such as changes in room temperature, changes in the amount of direct sunlight, and the importance of air conditioning.

In the comparison processing waveform, there is a possibility that an upwardly convex waveform may appear even in a portion where a human body does not exist, which may cause false detection.

In this way, in the conventional example, when the human body is not present, the reference waveform can be updated by using the input waveform as the reference waveform and the influence of environmental changes can be removed. If the detection continues, the reference waveform cannot be updated, and there is a problem in that the influence of environmental changes within the detection area cannot be removed.

(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 detect the number of people with high accuracy by removing the influence of environmental changes within the detection area.

(Disclosure of the Invention) As shown in FIG. 2, the number of people detection device according to the present invention 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, and a preamplifier 3 that amplifies the output signal of the infrared detection element 2; a signal processor 4 that converts 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 detection device, which includes a judgment section 5 that judges the number of people based on the number of people, and an output section 6 that outputs the number of people information from the output signal of the judgment section 5, the judgment section 5 performs signal processing when there is no detected human body. The input waveform from unit 4 is stored in advance as a reference waveform, and the number of people is determined based on the difference between the input waveform and the reference waveform. It is configured so that parts are updated sequentially.

FIG. 2 is a diagram showing a schematic configuration of a number of people detection device according to an 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, 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. . bandpass filter 4
The output of 1 is input to the A/D converter 42, A/D converted by the A/D converter 42, and output to the microcomputer 51 constituting the determination section 5. The motor drive section 12 is controlled by a control signal from the microcomputer 51.
operates, and drives and stops the motor as necessary. In the rotation period detection section 13, a synchronization signal is output to the microcomputer 51 every rotation in synchronization with the scanning of the circular scanning optical system. The microcomputer 51 uses the A/D for each rotation based on the synchronization signal from the rotation period detection section 13.
Data from the converter 42 is taken in sequentially.

FIG. 3 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 unit 4 at equal angular intervals for one period of the circular scanning optical system 1, and the data stored in the input buffer of the microcomputer 51 is
When the microcomputer 51 is interrupted by the synchronization signal from the rotation period detection section 13, the microcomputer 51 first takes in the input waveform data accumulated in the input buffer for one period of the scanning system.

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 memory and subtracts it from the input waveform. This generates a comparison processing waveform. The maximum point is detected and counted from this comparison processed waveform, and the number of people information is output. If the number of detected people is 0, all nine waveforms are updated by the input waveform. Number of people detected is 1
In the case of Å or more, the reference waveform is divided into a part where the detected human body exists and a part where the detected human body does not exist and is updated using the method described below.

FIG. 1 is an explanatory diagram showing the method of updating the reference waveform in this embodiment, in which (a) shows the reference waveform X stored in advance in the judgment unit 5, and (b) shows the reference waveform X input to the judgment unit 5. The input waveform Y shown in FIG. 12(c) shows the comparison processing waveform 2 obtained by subtracting the reference waveform Y from the input waveform X, and the figure (d) shows the updated reference waveform X, respectively. In each of these waveforms, the portion X A + Y A , Z from time T0 to TI
A, XC correspond to the non-existing parts of the human body, and the parts X8.X from time T1 to T2. Y...2 days.

XD corresponds to the existing part of the human body. In order to detect a portion where a human body is present, for example, it is sufficient to search for a portion of the comparison processing waveform Z whose absolute value is equal to or higher than a predetermined level and which includes a maximum point of height corresponding to the human body.

Now, assume that it is determined that a portion ZB in the comparison processing waveform Z is a portion where a human body exists. This comparison processing waveform Z
, even in the part zA where the human body is not present, it is not exactly zero due to the influence of environmental changes. At this time, first, the input waveform YA of the part where the human body does not exist is set as a new reference waveform Xc. Furthermore, the average amount of change in the part zA where the human body does not exist is determined. That is, z
The average value a of the part A is: This value a is added as an average change to each point of the part XB in the reference waveform, and updated as a new reference waveform Xo.

As described above, the feature of the present invention is to divide the reference waveform X into a portion xA where a human body does not exist and a portion XB where a human body exists,
For the portion xA where the human body does not exist, the current input waveform YA is updated as the reference waveform XC. With this, it is possible to always update the reference waveform at least for parts where the human body does not exist. Furthermore, regarding the portion XB where the human body is present, it is possible to constantly update the reference waveform by estimating changes due to the environment and adding the average change amount a to the current reference waveform XB.

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'', ``in the room'', or ``guest'', others 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 stabilized. Moreover, it can be operated effectively.

FIG. 5 shows an example of a circular scanning optical system used in the above-mentioned number of people detection device. As shown in FIG. 2(a), the rotary plate 10 is placed at a distance Rb from the front surface of the light receiving surface of the infrared detecting element 2, and the rotating shaft 11 of the rotary plate 10 is positioned in the field of view of the light receiving surface of the infrared detecting element 2. It is placed on the center C, and the rotating plate 10 is rotated by a drive fi ellipse such as a motor. As shown in FIG. 5(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. It is configured so that it enters the 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 rotating plate 10 to the object plane B is Ra, then the instantaneous visual field length LV and the visual field width Dv on the object plane are expressed by the following equation. It becomes like this.

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 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 length Lv of the instantaneous field of view on the object surface, and the field width D
v is as shown in the following equation.

Rb+Ra Lv=□・La Rb Ra Dv=□・d Rb As can be seen from the above equation, the instantaneous visual field width Dv can be determined by selecting an appropriate Rb or d at a given instant, regardless of the aperture width Da of the cylindrical lens. The 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 the embodiment of FIG. It may be configured as follows. 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 cylindrical mirror M
The mirror length is LM, the mirror width is Dm, and the infrared detection element 2
When the diameter of the light-receiving surface is d, the instantaneous field of view length Lv on the object surface is
And the field width Dv is expressed by the following equation as in the case of using a cylindrical lens.

Rb+Ra Lv=□Laa Rb Ra Dv=□・d Rb Therefore, appropriate Rh or dt! - By selecting, a predetermined instantaneous field width Dv can be obtained, and by increasing the mirror width DM of the cylindrical mirror M, the optical gain can be increased. In the radial direction in circular scanning, the viewing angle θ at which the instantaneous visual field looks at the object surface B is expressed by the following equation.

By using such a circular scanning optical system, one input waveform can be obtained for each rotation, so that the presence or absence of a human body and the number of people can be easily detected by the determining section 5 having the above-described configuration.

(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. 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 human body to be detected, and at least the portion of the reference waveform other than the portion corresponding to the human body to be detected is updated sequentially. Because of this, the illumination waveform is updated even if a human body exists within the detection area, which has the effect of eliminating the effects of environmental changes within the detection area and allowing highly accurate detection of people. There is.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the operation of an embodiment of the present invention, FIG. 2 is a block diagram showing a schematic configuration of the embodiment of the invention, FIG. a) to (
c) is an explanatory diagram of the operation of the judgment unit same as above, FIG.
) is a bottom view of the essential parts of the same as above, 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 essential parts of the same as above, and FIG. 7 is a conventional FIG. 2 is a block diagram showing a schematic configuration of an example. 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.

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 determining unit is configured to store in advance the input waveform from the signal processing unit when no detected human body is present as a reference waveform, and determine the number of people based on the difference between the input waveform and the reference waveform, and . A number of people detection device, characterized in that it is configured to sequentially update at least a portion of the reference waveform other than the portion corresponding to the detected human body.