JPH06186352A - Multi-beam human body detector - Google Patents

Abstract

PURPOSE:To obtain an inexpensive, high sensitivity human body detector by a constitution wherein the spatial frequency in the sensitivity distribution of a detection beam formed in grid is set identically in longitudinal and lateral directions by the use of a general purpose dual type infrared detecting element and a multi-split lens. CONSTITUTION:Infrared rays emitted from a human body are condensed through a multi-split condenser lens 1. In the embodiment, a 25 split FRESNEL lens having focal length of 10mm is employed wherein the main points 11 of respective lenses are arranged in grid and the length between main points in the direction normal (lateral) to the arranging direction of sensing elements 21, 21 is set two times as long as the length between main points P. The sensing elements 21 of dual type infrared element 2 has dimensions of 1mm width and 2mm length and when the sense elements are combined with the split lens 1, an accurate grid type light receiving plane can be provided on the screen. Since frequency components of incident power waveform, being produced when the human body moves in longitudinal or lateral direction, have peak values at an identical frequency, signal waveform can be extracted efficiently regardless of the moving direction of the human body thus enhancing detection accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-beam human body for detecting the presence of a human body by detecting the amount of change in infrared rays that occurs when the human body passes through a plurality of detection beams that are radially spread and formed. Regarding the detection device.

[0002]

2. Description of the Related Art As a device for detecting a human body by a change amount of infrared rays, a device generally called a pyroelectric device is widely used. Compared to the method of projecting near infrared rays to detect the amount of change in the reflected light, the method using such a pyroelectric element does not require a light emitting device and can change the optical system condition of the condenser. Since different detection areas can be set easily,
It is rapidly becoming popular as a security intrusion detector and automatic lighting switch.

However, since the pyroelectric element is a change amount detecting element for detecting a change in temperature and detects passage of a detection beam of a human body, it outputs a detection signal when a human is operating. , In the case of continuously detecting the presence of a human body in a limited space, it does not output a detection signal even if a human is present. There was a problem that the control output was reversed and the load such as lighting was turned off even if there were people in the room.

Therefore, in order to prevent such a problem, the present applicants have set a pair of sensing elements arranged in parallel as
Adjacent detection beams using a four-element dual-type pyroelectric element and a multi-segment lens in which four sensing elements, which are vertically combined and arranged, have different polarities in both vertical and horizontal adjacent directions. By expanding and forming the grid in a grid pattern so that the vertical and horizontal directions have mutually opposite characteristics, and setting the size of the detection beam to be approximately the same as the human hand, which is the detection target, We previously proposed a multi-beam type human body detection device that can detect even slight movements of the human body such as hands and head.

[0005]

However, the four-element dual-type pyroelectric element used for such a purpose has low versatility and needs to be specially manufactured, resulting in high cost. This is a factor that increases the cost of the detection device. The present invention is proposed to solve such a problem, and by forming a special detection pattern in a grid pattern by using a versatile dual-type infrared detection element and a multi-segment lens. An object of the present invention is to provide an inexpensive and highly sensitive multi-beam type human body detection device.

[0006]

SUMMARY OF THE INVENTION The present invention proposed to achieve the above object is to provide a multi-division condenser lens on the front surface of a light-receiving infrared detecting element in which two sensing elements having different polarities are arranged in parallel. The present invention relates to an improvement of a multi-beam type human body detection device configured by arranging the above-mentioned arrangements, and in particular, the spatial frequency of the sensitivity distribution of detection beams formed in a grid pattern is configured to be the same in the vertical and horizontal directions. There is.

According to the present invention as set forth in claim 2, the direction in which the adjacent detection beams are orthogonal to the distance between the detection beams in the directions in which the adjacent detection beams have opposite polarities, and the adjacent detection beams have the same polarity. The inter-detection beam distance is doubled.

[0008]

According to the present invention, a dual-type infrared detecting element having high versatility and a multi-division condenser lens are used to develop a grid-like detection pattern having the same spatial frequency in both vertical and horizontal directions. Since it is formed, the center frequency of the bandpass filter circuit required for detecting the detection signal can be set to be the same in both the vertical and horizontal movement directions. Therefore, it is possible to inexpensively provide a human body detection device having high sensitivity for detecting the movement of the human body regardless of the moving direction of the human body.

It is generally known that the frequency of the detection pulse output when the target moves in the detection beam is determined by the spatial frequency of the sensitivity distribution of the detection beam when the moving speed of the target is the same. In the present invention, using this principle, the center frequency of the band-pass filter circuit in the signal processing unit is made common to both vertical and horizontal movements. Therefore, the configuration of the signal processing unit can be simplified.

[0010]

FIG. 1 is a block diagram showing an embodiment of the present invention. This human body detection device includes a multi-division condenser lens 1 that collects infrared rays emitted from a human body, a dual-type infrared detection element 2 that detects the collected infrared rays, and a signal amplification unit 3 that amplifies the output of the infrared detection element 2. A bandpass filter circuit 4 that removes unnecessary frequency components and extracts only the detection signal, a comparison circuit 5 that compares the detection signal with a preset threshold value to determine the detection of the human body, and an output signal when the human body is detected. It is composed of a delay circuit 6 for holding for a predetermined time and an output control unit 7 for outputting a control signal to a connected load, and the control signal from the output control unit 7 turns on / off the lighting etc. installed in the room. It is supposed to do.

FIG. 2 shows an example of a dual type infrared detecting element used in the present invention. Two sensing elements 21 and 21 having different polarities are arranged in parallel, each dimension of the sensing elements 21 and 21 serving as a light receiving surface is 1 mm × 2 mm, and an element interval D is 1 mm. The polarity connected to 21 is selected to give positive and negative electric characteristics. Such a dual type infrared detection element 2
As the material, those widely used in general human body detection devices can be used.

FIG. 3 shows a multi-division condenser lens used with a dual type infrared detection element in the present invention. It is a 25-divided lens with a focal length f = 10 mm, and is composed of a Fresnel lens made of polyethylene, so that the deployment position of the detection beam is determined by the principal point position 11 (center position) of each lens. Has become. In the illustrated example, the principal point positions 11 of the respective lenses are arranged in a grid pattern, and the principal point position p in the direction perpendicular to the principal point distance p in the direction in which the sensing elements 21 and 21 of the infrared detection element 2 are arranged. The distance is set to 2p and they are arranged so as to be doubled, and a detection beam pattern as shown in FIG. 6 is obtained. FIG. 6 shows a detection beam pattern on the floor surface 2 m directly below when the human body detection device of the present invention is installed on a ceiling. The size of one beam is 20 cm × 40 cm.
The distance between frames is 40 cm in the horizontal direction and 80 c in the vertical direction.
It has become m.

Next, the principle adopted in the human body detection of the present invention will be examined based on the spatial filter theory.
Generally, the frequency characteristic V (ω) of the sensor output V (t) of the light receiving type infrared detection element caused by the movement of the target is
When an ideal optical system without aberration is used, a light intensity distribution s in the moving direction of the moving target image formed by the optical system
(X), the spatial frequency characteristic is S (ωx), the transmittance distribution in the moving direction of the target of the light receiving element is r (x),
If this spatial frequency component is R (ωx), the sensitivity frequency characteristic of the element with respect to incident light is D (ω), the frequency characteristic of the amplification section is A (ω), and the moving speed of the target image is m, the frequency is The following relational expressions hold in the domain. V (ω) = R * (ω / m) × S (ω / m) × D (ω) × A (ω) where R * is the complex conjugate number of R. The transmittance distribution r (x) of the light receiving element shows the shape of the light receiving surface.

By the way, from the above equation, the incident power waveform incident on the device is determined by the shape of the target image, the shape of the light receiving surface, and the moving speed of the target image.
It can be said that the electrical frequency characteristics of the elements of the signal processing section and the amplification section must be determined by selecting the optimum characteristics according to the frequency characteristics. Further, in order to obtain a stable output regardless of the moving direction of the target, it is necessary to obtain an incident power waveform with equal frequency characteristics in both the vertical and horizontal directions of the detection beam, but the target shape is constant. In that case, the transmittance distributions of the light receiving elements may be equal in the vertical and horizontal directions.

In the dual type infrared element 2 shown as an embodiment of the present invention in FIG. 2, the sensing elements 21 and 21 serving as the light receiving surfaces are 1 mm in the horizontal direction and 2 mm in the vertical direction, so that they are viewed as one element. In this case, the spatial frequency characteristics differ in the vertical and horizontal directions, and thus the incident power waveform varies depending on the moving direction. However, in the human body detecting apparatus of the present invention using such a dual type infrared element 2 in combination with the multi-division condenser lens 1, the light receiving surface on the image plane and the detection beam arrangement on the object plane. Can be considered to be arranged in a grid pattern. The light-receiving surface transmittance distribution at that time is as shown in FIG. 8 in the horizontal direction r1 (x) and the vertical direction r2 (x), and thus the spatial frequency characteristics thereof are as shown in FIG. (Ωx) and R2 (ωx) in the vertical direction, and although the values of the DC component are different, it can be seen that the center frequencies showing the maximum level above that are the same.

Generally, since the light receiving type infrared detecting element such as the dual type infrared detecting element is a change detecting element, the direct current component can be neglected. Therefore, the frequency of the incident power waveform generated in response to the movement of the target in the horizontal and vertical directions. The component takes a peak value at the same frequency, and therefore the signal waveform can be efficiently extracted regardless of the moving direction by the element sensitivity frequency characteristic and the amplification section frequency characteristic.

[0017]

As described above, the present invention uses the dual type infrared detecting element and the multi-divided condenser lens to detect the spatial distribution of the spatial frequency of the sensitivity distribution of the detection beam radiatively expanded in a lattice pattern. Since they are made the same, the signal component can be efficiently extracted regardless of the moving direction of the target, and an inexpensive and high-performance human body detection device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing an internal configuration of a human body detection device of the present invention.

FIG. 2 is a structural explanatory view showing an embodiment of a dual type infrared detecting element used in the present invention.

FIG. 3 is a structural explanatory view showing an embodiment of a multi-division condenser lens used in the present invention.

FIG. 4 is an explanatory diagram of a detection beam pattern developed and formed by the human body detection device of the present invention.

5A is a diagram showing a moving target image intensity distribution, FIG.
FIG. 7B is a diagram showing a light receiving surface transmittance distribution.

6A is a diagram showing frequency characteristics of a target image, and FIG. 6B)
Is a diagram showing the light receiving surface transmittance frequency characteristic, c) is a diagram showing the element sensitivity frequency characteristic, and d) is a diagram showing the amplification unit frequency characteristic.

FIG. 7 is a diagram showing a light receiving surface transmittance distribution (lateral direction) by the human body detection device of the present invention.

FIG. 8 is a diagram showing a spatial frequency characteristic of a light receiving surface transmittance distribution (horizontal direction) by the human body detection device of the present invention.

FIG. 9 is a diagram showing a light receiving surface transmittance distribution (longitudinal direction) according to the human body detection device of the present invention.

FIG. 10 is a diagram showing a spatial frequency characteristic of a light receiving surface transmittance distribution (longitudinal direction) by the human body detection device of the present invention.

[Explanation of symbols]

 1 ... Multi-division condensing lens 2 ... Dual type infrared detection element 21 ... Sensing element

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[Procedure amendment]

[Submission date] June 23, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

Next, the principle adopted in the human body detection of the present invention will be examined based on the spatial filter theory.
Generally, the frequency characteristic V (ω) of the sensor output V (t) of the light receiving type infrared detection element caused by the movement of the target is
When an ideal optical system without aberration is used, a light intensity distribution s in the moving direction of the moving target image formed by the optical system
(X), the spatial frequency characteristic is S (ωx), the transmittance distribution in the moving direction of the target of the light receiving element is r (x),
If this spatial frequency component is R (ωx), the sensitivity frequency characteristic of the element with respect to incident light is D (ω), the frequency characteristic of the amplification section is A (ω), and the moving speed of the target image is m, the frequency is The following relational expressions hold in the domain. V (ω) = R * (ωx / m) × S (ωx / m) × D (ω) × A (ω) where R * is the complex conjugate number of R. The transmittance distribution r (x) of the light receiving element shows the shape of the light receiving surface.

Claims (2)

[Claims] 1. A multi-beam type human body detection device comprising a multi-division condensing lens arranged in front of a light-receiving infrared detecting element in which two sensing elements having different polarities are arranged in parallel to each other. A multi-beam type human body detection device, characterized in that the spatial frequencies of the sensitivity distribution of the detection beam formed in the above are configured to be the same in the vertical and horizontal directions. 2. The multi-beam type human body detection device according to claim 1, wherein adjacent detection beams are orthogonal to a distance between the detection beams in directions of opposite polarities, and adjacent detection beams have the same polarity. A multi-beam type human body detection device in which the distance between the detection beams in the direction to be doubled is doubled.