JPS63292391A - Person number detecting device - Google Patents

Abstract

PURPOSE:To prevent a malfunction caused by radiation heat from a background which is warned by the human body, by deciding the number of persons by using an output signal from a signal processing part of a plural period portion by a deciding part. CONSTITUTION:The titled device is constituted of an infrared ray detecting element 2, a scanning optical system 1 for scanning a visual field of the infrared ray detecting element 2, a pre-amplifying part 3 for amplifying an output signal of the infrared ray detecting element 2, a signal processing part 4 for converting an output signal of the pre-amplifying part 3 to a signal required for detecting the number of persons, a deciding part 5 for deciding the number of persons based on an output signal of the signal processing part 4, and an output part 6 for outputting the person number information from an output signal of the deciding part 5. In this state, in the deciding part 5, the number of persons is decided by using the output signal from the signal processing part 4 of a plural period portion. In such a way, since the signal of a plural period portion is utilized, radiation heat from the human body and radiation heat from a background which is warmed by the human body can be discriminated, and a malfunction is prevented.

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 developed a highly accurate number of people detection device having a wide detection area with a simple and inexpensive configuration (Japanese Patent Application No. 61-281301).
) has already been proposed. This device for detecting the number of people, the schematic configuration of which is shown in FIG.
, 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 the signal processor 4.
It consists of a determining section 5 that determines the number of people based on the output signal of the determining section 5, and an output section 6 that outputs the number of people information from the output signal of the determining section 5, making it possible to detect the number of people within a wide detection area with high accuracy. It is something.

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. FIG. 6 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. 6(b)) and the reference waveform data (FIG. 6(a)), and the result is Compare newly processed waveform data (
In the comparison processing waveform shown in FIG. 6(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 such a device, if a human body is sitting on a chair or carpet, the heat transferred from the human body warms the background object such as the chair or carpet, and even after the human body leaves, the background object radiates heat, making it appear as if the human body is Since the temperature distribution becomes as if it were present, there was a problem that an error occurred in the number of people detected.

(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 can prevent malfunctions due to radiant heat from a background warmed by human bodies.

(Disclosure of the Invention) FIG. 3 is a block diagram showing a schematic configuration of the present invention. The number of people detecting device of the present invention includes an infrared detecting element 2, a scanning optical system 1 that scans the field of view of the infrared detecting element 2. , 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 a signal processor 4 of the signal processor 4. a determining unit 5 that determines the number of people based on an output signal; and the determining unit 5
and an output section 6 that outputs the number of people information from the output signal of the apparatus, and is characterized in that the judgment section 5 is configured to judge the number of people using the output signals from the signal processing section 4 for a plurality of periods. It is.

In this way, the present invention utilizes signals for multiple cycles, so it is possible to distinguish between radiant heat from the human body and radiant heat from the background warmed by the human body, thereby preventing malfunctions. be.

FIG. 4 is a block diagram showing the circuit configuration of 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, 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. . The output of the bandpass filter 41 is input to the A/D converter 42.
2, the signal is A/D converted and output to the microcomputer 51 constituting the determining section 5.

The motor drive section 12 operates according to a control signal from the microcomputer 51, and drives and stops the motor of the scanning optical system 1 as necessary.

Here, as shown in FIG. 7, the scanning optical system 1 is constructed by, for example, rotating a rotary plate 10 with a motor 14, which is attached to a concave cylindrical mirror M so that its generatrix direction is parallel to the radial direction. The rotation axis 11 of the zero-rotation plate 10 is arranged on the center of the field of view of the light-receiving surface of the infrared detection element 2.

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 scanning optical system 1. The microcomputer 51 controls one of the scanning optical systems 1 based on the synchronization signal from the rotation period detection section 13.
Data from the A/D converter 42 is sequentially taken in every rotation.

FIG. 5 is a flow chart for explaining the basic operation of the determining section 5 in this embodiment. A predetermined number of data is sent from the A/D converter 42 in the signal processing unit 4 at equal angular intervals for one period of the scanning optical system 1, and the data stored in the input buffer of the microcomputer 51 is
The microcomputer 51 is interrupted by the synchronization signal from the rotation period detection section 13, and the microcomputer 51 first takes in the input waveform data accumulated in the input buffer for one cycle of the scanning optical system 1. In this case, an input waveform obtained when a human body is not present within the detection area is stored in advance in the memory as reference waveform data. Micro Combiator 51
reads this pre-stored reference waveform (see Fig. 6 (&)) from memory and converts it to the input waveform (Fig. 6 (b)).
)), thereby generating a comparison processing waveform (see FIG. 6(C) 9). The maximum points are detected from this comparison processed waveform, and the detected maximum points are counted.
The number of people information is output based on the result of counting the maximum points.

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.

Next, the method of detecting the number of people, which is a feature of the present invention, will be explained based on FIG. FIG. 2(a) shows the reference waveform R at time 0 (t-1), when there is one human body, the input waveform is It-+, and this is the input waveform when the zero human body shown in FIG. 2(b) is If you are sitting on a chair or carpet, the heat transmitted from your body warms the background object such as the chair or carpet, and the heat is radiated from the background object even after the human body leaves. FIG. 2(c) shows this situation, and shows the input waveform It after the human body leaves the visual field at time 0 (t-1> and time t
The comparison processing waveforms St-+ and St are shown in FIG. 2(d).
As is clear from this figure, at time t,
If the number of people is detected by counting the maximum points from the comparison processed waveform St obtained by taking the difference between the input waveform It and the reference waveform R, the radiant heat from background objects will be mistakenly detected as a human body.

Therefore, in such a case, it is desirable to determine that the maximum point is a background object without counting it as a human body. However, if the human body moves away from the person in the radial direction from a place relatively close to the people detection device, or if the infrared radiation from the human body temporarily weakens because the detected human body wears a hat or changes its posture, I t-+ and I described above
Since a waveform similar to t may be obtained, it is difficult to distinguish between radiant heat from the human body and radiant heat from a warmed background object. In order to distinguish between heat and heat, the following processing is performed.

FIG. 1 is a flowchart of the number of people detection and foreground object removal routine in this embodiment. First, the number of people is detected from the comparison processing waveform St at time t by counting the number of lost points, and when the detected number of people is 1 Å or more, it is determined whether the maximum point is due to the influence of the background object, and it is determined that the influence of the background object is. When there is a local maximum point, a process is performed to reduce the number of detected people by the number of local maximum points. To explain this in relation to FIG. 2, first, the comparison processing waveform St at time t is divided into an upwardly convex waveform portion B including one maximum point, and flat portions A and C. Then, when the maximum value Mt, that is, the local maximum value, is determined for the upwardly convex waveform portion B, Mt=Max(St> 0th order) Then, the comparison processing waveform S at time (t-1) is obtained.
When calculating the maximum value Mt-+ in section B for t-+, Mt-+ = Max(St-+) days. Compare these maximum values Mt and Mt-+, When it decreases by more than a preset threshold value T (>O), that is, when Mt-+Mt≧T, the waveform of section B at the time will change to the foreground of a chair, etc. after the human body has left. This can be considered to be the effect of residual heat remaining in the object.

However, as described above, there are cases in which it cannot be determined that the object is not a human body based solely on the fact that the maximum value decreases by more than the threshold value T. Therefore, by processing the part surrounded by the one-dot chain line in FIG.
+j (1≦j≦n; n is a preset positive integer)
Find and compare with Mt. If the maximum value Mt is not radiant heat from the human body, the transition of the maximum value during n cycles is N<N
should be within the noise tolerance). Therefore, if Mt・ and Mt+J are in the relationship l M t−M t+j l ≦N, then the maximum value Mt is considered to be the effect of the residual heat of the background object rather than the radiant heat from the human body. , when the maximum value Mt is radiant heat from the human body, the transition of the maximum value during n cycles is larger than the noise tolerance value N, so the condition of the above equation is not satisfied. Therefore, in this case In this case, the maximum value Mt is considered to be the peak due to radiant heat from the human body.

As described above, it is now possible to distinguish between the direct radiant heat of the human body, which could not be distinguished just by comparing the reference waveform and the input waveform, and the heat of the background object warmed by the heat transmitted from the human body. can be reliably detected.

In addition, in Fig. 2, for convenience of explanation, a reference waveform with only one maximum point is shown as an example, but even if there are multiple maximum points, the waveform can be divided into an interval including each maximum point and a flat interval. death,
Needless to say, similar processing is performed for all sections including the local maximum point.

In addition, in this embodiment, the maximum value Mt obtained last time
After detecting that the current maximum value Mt has decreased by more than the threshold value T compared to -+, the maximum value Mt for n cycles is
When the transition of t+j (1≦j≦n) is within the noise tolerance value N, the maximum value Mt is determined to be due to the residual heat of the background object. M
The trend of t+J is monotonically decreasing, that is, Mt+J<M
When t+J-+ (1≦j≦rl), the maximum value Mt
The configuration may be such that it is determined that this is due to the influence of a background object.

Furthermore, in the description of the embodiment, an example was shown in which the field of view of the infrared detection element is scanned by a circular scanning optical system, but it is also possible to scan the field of view of the infrared detection element using another scanning optical system, for example, a parallel scanning optical system. Needless to say, it's a good thing.

(Effects of the Invention) As described above, the present invention uses an infrared detection element and a scanning optical system to detect the human body and count the number of people, so it can be configured easily and inexpensively, and moreover, it can be configured easily and inexpensively. Since it is configured to determine the number of people using the output signal from the signal processing section corresponding to the period, it is effective in preventing malfunctions due to radiant heat from the background warmed by the human body.

[Brief explanation of the drawing]

Figure 1 is a flowchart showing the main operations of the present invention, and Figure 2 (a
) to (d) are operation explanatory diagrams of the present invention, and 3rd e? I is a block diagram showing the basic configuration of the number of people detection device according to the present invention, FIG. 4 is a block diagram showing the circuit configuration used in the same, FIG. 5 is a flowchart for explaining the operation of the same, and FIG. 6 (a) ~(
c) is an operating waveform opening same as above, and FIG. 7 is a schematic configuration diagram of a scanning optical system used in same. 1 is a 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 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. . A number of people detection device, characterized in that the determination unit is configured to determine the number of people using output signals from the signal processing unit for a plurality of periods.