JPH0260273B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a situation monitoring device that detects the number and position of people using a pyroelectric infrared detection element, and is used for crime prevention in an elevator car, for example. It can also be used for detecting waiting passengers in elevator halls, canceling prank calls in elevator cars, and optimally performing emergency rescue operations.

[Description of prior art]

Methods for detecting people within a limited range using a pyroelectric infrared detection element (hereinafter simply referred to as a detection element) include scanning the optical system (image plane scanning or object plane scanning) or chipping. There is a method to do this by converting a DC signal to AC using a .
An example of the former is JP-A-59-60587, and an example of the latter is JP-A-56-161271.

[Problem that the invention seeks to solve]

In the optical scanning method, the field of view is scanned by rotating a mirror, so the background that the sensing element sees constantly changes, and there is no point that can be used as a reference point for temperature.
It has the disadvantage that it is easily affected by the inside of the optical system (the inner surface of the case that houses the scanning motor and mirror), that is, it is easily affected by the ambient temperature.
There is a problem with detection accuracy. Furthermore, a relatively large scanning motor is required, and in particular, in the object surface scanning method, a large scanning mirror is required, resulting in an increase in the size of the apparatus.

The method using a chopper simplifies the device configuration, but has the problem that it is more susceptible to background noise (particularly temperature) than the optical scanning method.
Furthermore, in any of the above methods, in order to divide the field of view into multiple fields and detect the number and position of people in each field of view, there is a problem that multiple detection elements must be provided corresponding to each field of view. be.

[Means for solving problems]

The present invention is characterized in that pinholes are used to solve the above problems. In other words, when using a pinhole, (1) the brightness is insufficient, and (2) when the diameter of the pinhole is increased, the difference in brightness between the vicinity of the optical axis and the periphery increases, resulting in a blurred image. Although there is a problem that the target of detection is limited to a relatively short distance (about several meters), (1) there is no distortion in the image because it is generated by point projection, and (2) it can be detected at any distance. It focuses on the ability to focus on objects such as , and is unique in that it performs pinhole scanning.

The present invention has a fixed slit for dividing the visual field into a plurality of parts and setting corresponding visual fields, and a plurality of slits corresponding to each of the fixed slits and intersecting the fixed slit to form a pinhole. A rotary plate in which the positions of the slits are shifted so that the pinholes are not formed at the same time, a means for driving the rotary plate at a constant speed, and a signal synchronized with the rotation of the rotary plate. a signal detection section comprising an infrared detection element that outputs a signal in response to a change in incident infrared rays incident from each field of view through the pinhole; and an output signal of the infrared detection element. and a signal processing section that determines the number of people and positions within each field of view based on the synchronization signal of the rotary plate.

The pinhole is formed at the intersection of the fixed slit and the slit of the rotary plate, and scanning is performed by rotating the rotary plate.

In addition, to divide the field of view, multiple fixed slits are provided, and the slits corresponding to each fixed slit are placed on the rotating plate at different positions, so that the timing of pinhole scanning is different for each field of view, and one detection element Detection of each field of view is performed using .

〔Example〕

FIG. 1A is a diagram showing the appearance of one embodiment of the sensing section according to the present invention. In the figure, 1 is the entire sensing section, 2 is a case, and 3 is a rotating plate attached to the front of the case 2. It is driven at a constant speed by a motor (not shown). The rotating plate 3 has slits S1A to S1C and
S2A to S2C are provided and serve as a reticle plate.

FIG.
LA to LC are provided, and as the rotary plate 3 rotates, slits S1A and S2A intersect with slit LA, and similarly, slits S1B and S2B intersect with slit LA.
LB and slits S1C and S2C intersect with slit LC, respectively. 4 is a detection element fixed inside the case 2. Although the rotating plate 3 (reticle plate) is shown attached to the outside of the case 2 for convenience of explanation, it is actually preferable to attach it to the inside of the case 2 for reasons of design and the like.

FIG. 2 is a partially enlarged view of FIG. 1, showing how pinholes are formed by the intersection of the slits. Here, a pinhole P formed by the slits LA and S1A is shown, and as the rotating plate 3 rotates in the direction of the arrow, the pinhole P moves from the left end to the right end of the slit LA. Similarly, pinholes are sequentially formed in the slits LB and LC, which move as the rotary plate 3 rotates.

FIG. 3 is a diagram showing, as an example, a state in which a sensing section is attached to the ceiling of an elevator car in order to monitor the inside of the elevator car as a visual field. 5 is an elevator car, and here an example is shown in which the field of view is divided into three fields of view, zones A to C. The range of the A zone is set by the distance between the slit LA and the detection element 4 and the size of the slit LA.
The zone is set by the slit LB, and the C zone is set by the slit LC. When the rotary plate 3 rotates, the movement of the pinhole causes A
~C zone is sequentially scanned, and in this example, the rotary plate 3
Each zone will be scanned twice in one rotation of .

Figure 4 shows the relationship between the scanning position and the waveform of the output signal of the detection element 4 for the A zone over time on the horizontal axis. An example of a signal waveform is shown. Here, A zone is further divided into three parts a to c, B is when there is no person in A zone, C is when there is one person in a of A zone, and D is when there is one person in A zone. When there is one person in each of a to c,
E is the output waveform of each detection element 4 when two people are present in a of the A zone. Note that t ₁ is the start point of scanning in zone A, that is, slit S1A.
t2 indicates the point at which the LAs begin to intersect, and _t2 indicates the point at which scanning of the A zone ends, that is, the point at which the slits S1A and LA end their intersection.

Considering the case where the rotating plate 3 is attached to the inside of the case 2, no pinhole is formed just before time _t1 , and the detection element 4 is looking at the rotating plate 3, which is the background (reference). becomes.

Here, the radiant energy W from the target is given by the following equation according to the Stefan-Boltzmann law.
W=εδT ⁴ …(1) where ε: Target emissivity<1 δ: Stefan-Boltzmann constant T: Absolute temperature Therefore, the incident energy W ₁ on the sensing element 4 just before time t ₁ is the Assuming that the temperature is T ₀ (equal to the ambient temperature) and the emissivity is ε ₀ , W ₁ =ε ₀ δT ⁴ ₀ (2). And at time t ₁ a pinhole is formed,
At this time, assuming that there is no one in the field of view, radiant energy from the floor is added through the pinhole, and the incident energy W ₂ to the detection element 4 increases the floor temperature.
When T _f and the emissivity of the floor are ε _f , W ₂ = ε _f δT ⁴ _f (3). Incident energy W ₁ at this time t ₁
Due to the change from to W ₂ , the detection element 4 emits an output, but since there is almost no difference between T _f and T ₀ , the waveform becomes as shown in (b). Also, in general, T _f <
Since T ₀ , if we choose the emissivity so that ε _f > ε ₀ ,
The difference between W ₁ and W ₂ can be reduced.

If there is a person within the field of view, the incident energy _W3 to the sensing element 4 will increase the surface temperature of the human body.
When T _n and emissivity are ε _n (skin is 0.99), W ₃ =ε _n δT ⁴ _n (4). Since ε _n and T _n are large compared to others,
Due to the change from W ₁ to W ₃ or from W ₂ to W ₃ , the output waveform of the sensing element 4 becomes as shown in C or D. Furthermore, when two people are present in close contact with each other, the output is approximately twice as large as when there is only one person, as shown in E.

In this way, the detection element 4 sequentially outputs signals corresponding to zones A to C as the rotary plate 3 rotates, so by setting appropriate thresholds, it is possible to detect the presence or absence of people and the number of people at each position. can be detected.

FIG. 5 is a block diagram showing an embodiment of the overall configuration of the present invention, in which 10 is a signal processing section;
is a preamplifier, 12 is a low-pass filter for removing noise components, etc., 13 is a comparator, 1
4 is an output circuit, and 15 is a synchronization signal circuit.

Since the output signal of the detection element 4 has the waveform as described above, the preamplifier 11 and the low-pass filter 1
By appropriately setting the level of the comparator 13 via 2, it is possible to determine the presence or absence of a person. Furthermore, the distinction between one person and two people can be easily made by providing two comparator setting levels. In addition, since the rotary plate 3 always rotates at a constant rotational speed, the position can be determined by obtaining a synchronization signal for each rotation using, for example, a slit in the rotor plate and a photo interrupter, and based on this, the synchronization signal circuit 1
Timer (monostable multivibrator) by 5
etc., by generating synchronizing signal pulses with a width corresponding to the scanning period of each position in correspondence with each scanning period, and taking the logical product of these synchronizing signal pulses and the output of the comparator 13, it is easy to calculate the difference for each position. number of people can be obtained.

FIG. 6 shows, as an application example of the present invention, the number of people at each position obtained by the signal processing section is displayed on a display device to monitor the inside of an elevator car. be.

20 is a display device installed in a manager's room, etc., and a total of nine two-color LEDs 21 are installed corresponding to the positions of a to c in zones A to C in the car. If there is one person in zone a, the two-color LED 21 at the corresponding position lights up green, and in b, if there are two people in zone a, the two-color LED 21 corresponding to that position lights up. This shows how the LED lights up in red.

This allows the manager to know the status of the passengers in the car, and can be effective in preventing crime without infringing on privacy as with monitor TV.

It should be noted that the signal representing the number of people by location obtained by the present invention can be applied not only to the above embodiments but also to various forms of display devices and alarm devices, and can be used not only for crime prevention purposes. It can be used in a wide range of applications, such as detecting waiting passengers in elevator halls, canceling prank calls in elevator cars, and optimally controlling abnormal situations.

〔Effect of the invention〕

According to the present invention, since the field of view is scanned using a pinhole, there is no distortion in the image, and objects at any distance can be focused, as well as being immune to the effects of ambient temperature. High-precision detection can be performed with almost no interference, and only one detection element is required for multiple fields of view without using lenses or mirrors, making it possible to construct a compact and inexpensive structure.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the appearance of one embodiment of the sensing section in the present invention, FIG. 2 is a partially enlarged view of FIG. 1, and FIG.
The figure shows the sensor of the present invention installed in an elevator car, Figure 4 shows the relationship between the scanning position and an example of the waveform of the output signal of the detection element for zone A, and Figure 5 shows the present invention. FIG. 6 is a block diagram showing an embodiment of the overall structure of the invention, and FIG. 6 is a diagram showing an application example of the invention. 1... Sensing section, 2... Case, 3... Rotating plate, 4
...Detection element, 5...Elevator car, 10...
...Signal processing unit, 11...Preamplifier, 12...Low pass filter, 13...Comparator, 14...
...Output circuit, 15...Synchronization signal circuit, LA to LC,
S1A~S1C, S2A~S2C...slit, P...pinhole.

Claims (1)

[Claims] 1. It has a fixed slit for dividing the field of view into a plurality of parts and setting the corresponding field of view, and a plurality of slits corresponding to each of the fixed slits and forming a pinhole by intersecting the fixed slit, and each pinhole. a rotary plate in which the positions of the respective slits are shifted so that the slits are not formed at the same time; means for driving the rotary plate at a constant speed; and means for outputting a signal synchronized with the rotation of the rotary plate. , a signal detection unit including an infrared detection element that outputs a signal in response to a change in incident infrared rays incident from each field of view through the pinhole; and an output signal of the infrared detection element and the rotation plate. A situation monitoring device comprising a signal processing unit that determines the number of people and positions within each field of view based on a synchronization signal.