JPH06100661B2 - 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) Conventionally, as a person number detection device, a device for obtaining a person number determination output by capturing image data of a detection area using a television camera and performing image processing on the image data has been proposed. In the method of measuring the number of people by detecting the human body by the change in luminance, the S / N ratio is poor and sufficient detection accuracy is not obtained. Therefore, in order to improve the detection accuracy,
Image data without a human body is stored in advance as reference image data, and a method of comparing this with input image data has been attempted, but it was difficult to distinguish an object other than a human body from a human body. . The number of people detecting apparatus using such a television camera is generally complicated in processing, and at present, sufficient accuracy for detecting the number of people is not obtained although the system is large. Further, when a television camera is used, there is a risk of invading privacy, and there are many cases where it is not practically preferable.

In addition, it has been attempted to irradiate near-infrared light with a near-infrared camera by irradiating with near-infrared light, but a new near-infrared irradiation light source is required. In addition, there is a problem that the human body cannot be detected when the hair cannot be detected, for example, when the person wears a cap or even when the hair is white.

Furthermore, if an infrared camera is used instead of a TV camera with visible light to enhance human detection capability,
There are problems that the cost becomes high, the system becomes complicated, and the versatility is poor.

On the other hand, as a device for detecting the degree of congestion of an elevator or the like, a device using an infrared detecting element and a scanning optical system has been proposed (Japanese Patent Laid-Open Nos. 59-60587, 59-83078, and Sho-59-83078). 60
-63487), these devices require the use of a large number of infrared detection elements to obtain a wide field of view, and there are variations in the sensitivity distribution and dead zones within the detection area, which may affect the position and posture of the human body. As a result, there is a problem in that the detection results of the number of persons vary, and it is not possible to obtain sufficient number of persons detection accuracy.

(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 high-accuracy people detection device having a simple and inexpensive structure and a wide detection area.

(Disclosure of the Invention) Configuration FIG. 5 is a block diagram showing a schematic configuration of the present invention. The device for detecting the number of people of the present invention includes an infrared detection element 2, a scanning optical system 1 for scanning the field of view of the infrared detection element 2, and a preamplifier 3 for amplifying an output signal of the infrared detection element 2.
A signal processing unit 4 for converting the output signal of the preamplification unit 3 into a signal necessary for detecting the number of people; a judgment unit 5 for judging the number of people based on the output signal of the signal processing unit 4; 5, a scanning optical system 1 is a circular scanning optical system 1 for circularly scanning the field of view of the infrared detecting element 2.
The determination unit 5 is configured to detect the number of people by counting the maximum points of the output signal from the signal processing unit 4, so that the number of people in a wide detection area can be detected with high accuracy. It is the one.

First, the circular scanning method used in the present invention will be described. When the human body to be detected is viewed from above, it is as shown in FIG. This is the height 17 shown in Fig. 6 (a).
As a model of a human body in which a rectangular parallelepiped having a width of 0 cm, a width of 50 cm, and a depth of 20 cm is erected, four human body models m1 to m4 are arranged at the vertices of a square having a side of 3 m, as shown in FIGS. 6 (b) and (c). Then
It is a two-dimensional image by the human body models m1 to m4 projected on a plane parallel to the floor surface U at a point 3 m above the floor surface U. As is clear from the figure, the human body image seen from above looks at the side surface of the human body except when it is arranged at the center c of the visual field.
The image extends in the radial direction from the visual field center c. Further, the further the position of the human body is from the visual field center c, the more the human body image becomes in the radial direction. In consideration of the above points, as shown in FIG. 8, a rectangular slit-shaped field surface F is provided, and a circular scanning method in which the field surface F is rotated around the end points thereof is used to effectively and efficiently measure the human body. It can be detected, identified, and counted. FIG. 8 shows a scanning situation by the circular scanning method, where F is the visual field plane, Q is the scanning direction, and F ₀ is the entire effective visual field. Further, 11 is the rotation center of the visual field plane F, which coincides with the visual field center c of the infrared detection element 2.

Using this scanning method, four human body models shown in FIG. 6 (a) are arranged as shown in FIGS. 6 (b) and 6 (c), and each time when circularly scanned from above. FIG. 9 shows one cycle of change in incident energy on the rectangular slit-shaped visual field surface F in FIG. However, it is assumed that the surface of the human body model m1 to m4 has a higher temperature than the floor surface U, and therefore the radiated infrared energy is also large. Since the infrared detection element 2 has a characteristic that the larger the incident energy is, the larger the output signal is. Therefore, among the waveforms shown in FIG.
The four convex portions correspond to the human body models m2, m1, m3, and m4, respectively. Therefore, in the present invention, the number of people is detected by detecting the maximum points in the output signal from the infrared detecting element 2 and counting the number of the detected maximum points.

Example 1 FIG. 1 is a diagram for explaining an example of a maximum point detection method. As shown in FIG. 1, there is a feature that the polarity of the inclination is inverted before and after the maximum point. Therefore, the point where the polarity of the inclination is reversed can be detected as the maximum value.

FIG. 10 is a block diagram showing a circuit configuration used in this embodiment. 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, in the band-pass filter 41, it cuts unstable low frequency components and also cuts unnecessary high frequency components, and S /
Improve N ratio. The output of the bandpass filter 41 is input to the A / D converter 42, A / D converted by the A / D converter 42,
It is output to the microcomputer 51 that constitutes the judgment 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. The rotation cycle detection unit 13 synchronizes with the scanning of the circular scanning optical system 1 for each rotation, and
The sync signal is output to 51. The microcomputer 51 sequentially takes in data from the A / D converter 42 for each rotation of the circular scanning optical system 1 based on the synchronization signal from the rotation cycle detection unit 13.

FIG. 11 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 captures the input waveform data accumulated in the input buffer for one cycle of the circular scanning optical system 1. 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. From this comparison processing waveform, the maximum points as shown in FIG. 1 are detected and the detected maximum points are counted, and the number of people information is output based on the maximum point count result. When the number of detected persons is 0, the reference waveform is updated with the input waveform.

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. 12 shows a specific example of a circular scanning optical system used in the 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. 12 (b), the rotating 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. 12, when a 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 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 an optical gain, as shown in FIG. 13, a rotating plate 10 having a concave cylindrical mirror M fixed thereto is used.
May be configured to rotate about the visual field center 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 is Rb, the distance from the mirror surface of the cylindrical mirror M to the object surface B is Ra, and the mirror length of the cylindrical mirror M is L.
Assuming m, the mirror width is Dm, and the light receiving surface diameter of the infrared detecting element 2 is d, the instantaneous visual field length Lv on the object surface and the visual field width Dv are as in the case of using a cylindrical lens as shown in the following equations. .

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.

Embodiment 2 FIGS. 2 (a) to 2 (d) are views for explaining another example of the maximum value detection method. As described above, in the determination unit 5 of the number-of-people detection device, 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 , The presence / absence of a human body and the number of persons are simultaneously judged by comparing with the reference waveform in the memory. FIG. 2 is an explanatory diagram showing this state,
A comparison calculation is performed between the input waveform data (FIG. 2 (b)) and the reference waveform data (FIG. 2 (a)) to the determination unit 5, and the result is newly compared with the comparison waveform data (FIG. 2 (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. The upward convex waveform has one maximum point and large positive and negative slopes on both sides thereof. FIG. 2D is a graph showing the inclination at each point, and shows that there are large positive and negative inclinations before and after the maximum point. Therefore, the slope of each point is calculated, and the slope 0 from the point having a slope larger than the preset positive slope α to the point having a slope smaller than the preset negative slope β is 0. Can be detected as the maximum point.

Third Embodiment Still another example of the maximum point detection method will be described with reference to FIGS. 3 and 4. FIG. 3 shows the time change of the signal including the maximum point. A filter that replaces the value at time t with the maximum value of (2i + 1) pieces of data from time (t-i) to time (t + i) is an intra-section maximum value replacement filter. ) To time (t + i), the filter that replaces the value at time t with the minimum value of the (2i + 1) pieces of data is referred to as an intra-section minimum value replacement filter.

As shown in FIG. 4 (a), first, when the intra-section minimum value replacement filter is applied to the entire comparison processed waveform, the waveform shown by the solid line is converted to the waveform shown by the dotted line. When the intra-section maximum value substitution filter is further applied to the converted waveform, the waveform is converted into a waveform indicated by a chain line. Then, by subtracting the waveform indicated by the alternate long and short dash line from the waveform indicated by the solid line, only the maximum point has a positive value, and the remaining portion has a value of 0 in FIG. 4 (b).
It is possible to obtain a waveform as shown in, and the maximum point can be detected and counted from this waveform.

(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 light-receiving type people detection device that detects infrared rays emitted from a detected human body to detect the number of people. Since the number of people is measured by counting the maximum value of the signal, the configuration is simple and inexpensive, and the detection result of the number of people may vary depending on the position and posture of the human body while having a wide detection area. This has the effect that the number of people can be measured with high accuracy.

[Brief description of drawings]

FIG. 1 is an operation explanatory view of one embodiment of the present invention, and FIG. 2 (a).
(D) is an operation explanatory view of another embodiment of the present invention, FIGS. 3 and 4 are operation explanatory views of still another embodiment of the present invention,
FIG. 5 is a block diagram showing the basic configuration of the number-of-people detecting device according to the present invention, FIG. 6 (a) is a perspective view showing a human body model for explaining the operation of the present invention, and FIG. FIG. 7C is a side view showing the arrangement of the models, FIG. 7C is a plan view showing the arrangement of the human body model above, and FIG. 7 is a plan view showing a two-dimensional image of the arrangement of the human body model above seen from above. , 8th
FIG. 9 is an explanatory diagram showing a situation of circular scanning used in the present invention, FIG. 9 is an explanatory diagram showing a temporal change of incident energy by the circular scanning, and FIG. 10 is a circuit configuration used in the embodiment of FIG. FIG. 11 is a block diagram, FIG. 11 is an operation explanatory diagram of the same as above, FIG. 12 (a) is a schematic configuration diagram showing an example of an optical system used in the embodiment of the same, and FIG.
FIG. 13A is a schematic configuration diagram showing another example of the optical system used in the above-mentioned embodiment, and FIG. 13B is a bottom view of relevant parts. 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.

Front page continuation (72) Inventor Takashi Horii 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. (72) Inventor, Hiroshi Matsuda 1048, Kadoma, Kadoma, Osaka Prefecture (72) Inventor, Kiritahata Shinji 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd.

Claims (3)

[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 a circular scanning optical system that circularly scans the field of view of the infrared detection element, and the determination unit is configured to detect the number of people by counting the maximum points of the output signal from the signal processing unit. An apparatus for detecting the number of people, characterized by comprising: 2. The determination unit determines that a slope sandwiched between a point where the slope of the output signal from the signal processing unit is a positive slope equal to or larger than a predetermined value and a point where the slope is a negative slope equal to or smaller than a predetermined value. The number-of-people detecting device according to claim 1, wherein the number of zero points is counted as a maximum point. 3. The determination unit replaces the value of the output signal from the signal processing unit at each time point with the minimum value within a predetermined interval including the value, and a minimum value replacement filter within the interval. A maximum value replacement filter within a section that replaces the value of the output signal of the value replacement filter at each time point with the maximum value within a predetermined section including the value, and performs signal processing on the output signal of the maximum value replacement filter within the section. The person number detecting apparatus according to claim 1, wherein the maximum number is counted by a signal subtracted from the output signal from the unit.