JPS63134987A - Person number detector - Google Patents

Abstract

PURPOSE:To eliminate influence of an environmental variation of a detection area, and to detect the number of persons with high accuracy by storing in advance a waveform which is inputted successively to a deciding part at every one rotation of an optical system for scanning circularly a visual field of an infrared ray detecting element, and using the difference between the previous scanning waveform and the present scanning waveform. CONSTITUTION:A rotary plate 10 provided with a slit A is placed in a position of a distance Rb from the front of the photodetecting surface of an infrared ray detecting element 2, and among infrared rays radiated from an object surface B, only that which has passed through the slit A is made incident on the infrared ray detecting element 2. A storage part 5a for storing a waveform which is inputted successively from a signal processing part 4 to a deciding part 5 at every one rotation of such a circular scanning optical system 1 is provided on the deciding part 5, and the deciding part 5 decides the number of persons by using a waveform of a difference obtained by subtracting a waveform of the previous scanning period stored in the storage part 5a, from a waveform of the present scanning period inputted to the deciding part 5 from the signal processing part 4.

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. 6 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 field/external ray detection element 2, and a preamplifier 3 that amplifies the output signal of the infrared detection element 2. a signal processing unit 4 that converts the output signal of the preamplifier 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 section 6 that outputs the number of people information from the output signal of the determining section 5. This allows for accurate detection.

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 in 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. It is compared with a reference waveform, and the presence or absence of a human body and the number of people are determined at the same time. In other words, a comparison operation is performed between the input waveform data and the reference waveform data, the result is used as new comparison processed waveform data, local maximum values are detected in the comparison processed waveform data, and the number of local maximum values is counted as the number of people. . In the comparison processing waveform data, if the detected number of people is 0, 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, with this method, the reference waveform cannot be updated unless the number of detected people reaches O, so the same reference waveform may be used for a long time without being updated. In this case, environmental changes within the detection area There was a problem that it was not possible to remove the influence of

(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. 1, 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 detecting device, which includes a determining section 5 that determines 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 determining section 5, the signal processing section The determining unit 5 is provided with a storage unit 5a for storing waveforms sequentially inputted from 4 to the determining unit 5.
The number of people is determined using the waveform of the difference obtained by subtracting the waveform of the previous scanning period stored in a from the waveform of the current scanning period input from the signal processing section 4 to the determining section 5. It is something.

In other words, the invention! I! The characteristic is that the waveform sequentially outputted from the signal processing section 4 to the judgment section 5 is synchronized with the rotation of the circular scanning optical system 1, and the judgment section 5 is outputted every cycle of the circular scanning optical system 1.
By accumulating it in the storage unit 5a and taking the difference between waveforms corresponding to temporally adjacent cycles, the influence of waveform fluctuations other than the human body due to changes in the surrounding environment is removed, and the number of people can be detected with high precision. There is a particular thing.

FIG. 2 shows one period of the output waveform output from the signal processing section 4 to the judgment section 5. FIG. As an example, the figure (b) shows the output waveform of one cycle Tn following the one cycle in the figure (,). Since the maximum value of the output waveform corresponds to a human body, in the case of figure (a), three human bodies are detected, and in the case of figure (b), two human bodies are detected. There will be. On the other hand, the same figure (c) is the same figure (
This is a waveform obtained by subtracting the waveform in (a) of the same figure from the waveform in (b), indicating that the number of people has decreased by one.

Now, the output waveform (Fig. 2(a)) at period Tn is
Consider a case where the output waveform (FIG. 2(b)) in the next cycle 'rn++ is inputted while being stored in the storage unit 5a of the determining unit 5. It is assumed that the number of people is detected as "3 people" from the output waveform in Fig. 2 (a) at period Tn.From the output waveform of +l (Fig. 2 (h)), the output waveform at period Tn (Fig. 2 (a)) to calculate the difference waveform (Fig. 2 (C)). The local maximum value and local minimum value are detected from the zero-order difference waveform. In this case, the voltage zero level The local maximum value is detected for the part of the waveform that is above the voltage level, and the local minimum value is detected for the part of the waveform that is below the voltage zero level, and the number of local maximum values and local minimum values are counted. , assign a positive sign to the number of local maximum values and a negative sign to the number of local minimum values, and add each number to obtain the fluctuating number of people 0 For example, Fig. 2 (c) In this case, there is no local maximum value in the positive voltage area, and one local minimum value exists in the negative voltage area, so using the above calculation method, the number of fluctuating numbers is: o + (-1) = -1 (person). Therefore, the number of people detected in period Tn+l is the number of people detected in period Tn (in this example, ``3 people'') and the fluctuating number of people detected by the difference waveform (in this example, ``-1 person'').
) is calculated as "2 people".

In this detection method, the detection of local maximum values (or minimum values) for detecting the number of people is performed using only the waveform after removing the influence of waveform fluctuations due to changes in the surrounding environment other than the human body, so it is highly accurate. It is possible to detect the number of people. That is, the second
The waveforms in Figures (a) and (b) are both affected by the surrounding environment and show fluctuations in the waveforms in areas other than the human body detection section. Therefore, if the local maximum value is detected directly from these waveforms, there will be a detection error. However, in this detection method, as shown in Fig. 2(a)(b)
We avoid detecting local maximum values directly from the waveforms of , but instead detect local maximum and minimum values from the waveform that is the difference between the two (Figure 2 (C)). Waveform fluctuations due to changes have been removed. In addition, compared to the conventional method in which the reference waveform is always stored in the judgment unit 5 and the number of people is detected using the difference between the reference waveform and the input waveform from the signal processing unit 4 to the judgment unit 5, the reference waveform The problem of how to update the data has also been resolved. Moreover, Fig. 2 (a
) The temporal difference in the waveforms shown in (b) is due to the circular scanning optical system 1.
Since it is one period of , it is short in terms of time, and fluctuations in the waveform due to changes in the surrounding environment during that period are relatively small, so the accuracy of detecting the number of people is improved.

In addition, in the case of FIG. 2, the period T. After the number of people detected at +l is calculated as “2 people”, the storage unit 5a of the judgment unit 5
The output waveform at period Tn shown in (a) of the same figure, which was stored in , is no longer needed, so it is stored in (b) of the same figure instead.
The output waveform at the period Tn□ shown in is stored in the storage section 5a. Then, in the next cycle of T n+ 2, the output waveform from the signal processing section 4 is taken in, and the cycle is T. The output waveform at period T n+ 1 is subtracted from the output waveform at period T n+ 1 to calculate the difference waveform. The following processing is similar to the above processing.

FIG. 3 illustrates how each waveform changes over four cycles. 3(a), (b), and (c) show the waveform stored in the storage unit 5a, the waveform output from the signal processing unit 4 to the determination unit 5, and the difference between the waveforms at the period Tn+1, respectively. It shows. In this case, the number of local maximum values of the waveform stored in the storage unit 5a is X=3, and the difference waveform,
Since the change that appeared in is Y=-1, the number of detected people is (X+
Y)=2.

Next, FIG. 3(d), (e), and (f) show the difference between the waveform stored in the storage unit 5a and the waveform output from the signal processing unit 4 to the determination unit 5 at the period T n+. The waveforms are shown respectively. The third
The waveform in Figure (d) shows that the signal processing unit 4
The waveform is the same as the waveform shown in FIG. The number of maximum values in this waveform is X=2, and the change appearing in the difference waveform is Y=±0, so the number of detected people is (X+Y)=2.

Next, FIG. 3(g)(h)(i) shows the waveform stored in the storage unit 5a and the signal processing unit Jh)AI! in the period Tn+1. 1II17r! 6. The waveforms shown in FIG.
It is the same as the waveform shown in FIG. 3(e) outputted to the signal processing section 4A/R determination section 5 in YA. The number of local maxima in this waveform is X=2, and the change that appears in the difference waveform is Y=
+1, so the number of detected people is (X+Y)=3.

Next, Fig. 3 (j) (k) (Z) is the period T n+
4 shows the waveform stored in the storage section 5a, the waveform output from the signal processing section 4 to the judgment section 5, and the waveform of the difference therebetween. The waveform of No. 31J(j) stored in the storage section 5a is the same as the waveform of FIG. 3(h) outputted from the signal processing section 4 to the determination section 5 at the period Tn+3. The number of local maxima in this waveform is X=
3, and the change appearing in the difference waveform is Y=-3, so the detected number of people is (X+Y)=O.

Hereinafter, the detected number of people can be obtained in the same manner after the period Tn+5.

FIG. 4 shows an embodiment of the circular scanning optical system used in the above-mentioned number of people detection device. As shown in FIG. The rotating shaft 11 at the center of the rotating plate 10 is placed on the field of view 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. 4(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 field of view 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 field of view length Lv and the 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.

When detecting people, the instantaneous field of view Dv on the object surface is the main factor that determines the number of people resolution.In order to increase the number of people resolution, the smaller the instantaneous field of view Dv, the better.Therefore, the aperture width Da of slit A should be made smaller. However, the amount of infrared light received decreases in proportion to this, 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. 4, when a cylindrical lens is placed in the slit A, and if the diameter of the light-receiving surface of the infrared detection element 2 is d, then 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.

Ra Dv=□・d Rb As can be seen from the above equation, the instantaneous visual field width Dv is determined by an appropriate Rb or dt! regardless of the aperture width Da of the cylindrical lens. - can be selected to obtain a predetermined instantaneous field width DV; 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. 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, and the cylindrical mirror M
The mirror length is Lm, the mirror width is Da, 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=□・L ring Rb Therefore, by selecting an appropriate Rb or d, a predetermined instantaneous field of view width Dv can be obtained, and by increasing the mirror width DI11 of the cylindrical mirror M, the optical gain can be increased. In the radial direction in zero circular scanning that can be performed, the viewing angle θ at which the instantaneous visual field looks at the object surface B is given by the following equation.

Next, the circuit configuration of a device for detecting the number of people using the optical system will be explained based on FIG. 1. 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 the A/D converted waveform every rotation in synchronization with the rotation of the circular scanning optical system 1, and subtracts the waveform in the previous scanning period stored in the storage section 5a from the input waveform. The output unit 6, which detects the number of people using the waveform of the difference obtained, displays the number of people information based on the number of people information given from the judgment 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
Evaluate the indoor situation based on ``0 people,'' ``1 person,'' and ``2Å or more.''
By displaying "absent,""present," and "guest" outside the room, others can easily and simply grasp 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 optical system that circularly scans the field of view of an infrared detection element in an infrared receiving type people detection device that detects the number of people by detecting infrared rays emitted from a detected human body. The waveforms that are sequentially input to the judgment unit every rotation are stored, and the number of people is judged using the waveform obtained by subtracting the stored waveform of the previous scanning period from the waveform of the current scanning period. Therefore, there is an effect that the influence of environmental changes within the detection area can be removed and the number of people can be detected with high accuracy.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the basic configuration of the present invention, Figure 2 (
a) to (e) and FIGS. 3(a) to (1) are explanatory diagrams of the operation of the present invention, FIG. 4(a) is a schematic configuration diagram of an optical system used in an embodiment of the present invention, and FIG. b) is a bottom view of the main parts of the same as above,
FIG. 5(a) is a schematic configuration diagram of an optical system used in another embodiment of the present invention, FIG. 5(b) is a bottom view of the main parts of the same, and FIG. 6 is a block diagram of a conventional 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, 6 is an output section, 5a
is the storage 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 provided with a storage unit that stores waveforms sequentially input from the signal processing unit to the determining unit every rotation of the circular scanning optical system, and the determining unit stores the waveforms of the previous scanning period stored in the storage unit. 1. A number of people detection device, characterized in that the number of people detection device is configured to determine the number of people using a waveform obtained by subtracting a waveform from a waveform of a current scanning period inputted from a signal processing unit to a determination unit.