JPH0260151B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of arranging elements of a crowding level detection device that measures crowding level from infrared rays emitted by a human body.

[Prior art and problems to be solved by the invention] With the aim of accurately detecting the number of people from infrared rays emitted by the human body with a simple and inexpensive configuration, the applicant previously filed Japanese Patent Application No. 57-172379 `` "Congestion Level Detection Device" (Japanese Unexamined Patent Publication No. 1983-60587) and Japanese Patent Application No. 1983-
No. 192763, ``Congestion Level Detection Device'' (Japanese Unexamined Patent Publication No. 1983-83078) was proposed. Although detailed explanations of these will be omitted, one embodiment of the basic configuration is shown in FIG.

In Fig. 1, 1 is a condensing lens 2, a plane reflecting mirror (scanning mirror) 3 that rotates at a constant period, and a detection element 4 (hereinafter simply referred to as the detection element) that responds to changes in the incident infrared rays. 5 is a scanning motor that drives the plane reflecting mirror 3, 6 is a preamplifier, 7 is a bandpass filter for removing noise components, etc.;
8 is a main amplifier; 9 is a comparator that outputs a pulse signal with an input signal of a predetermined level or higher; 10 is a multiplexer circuit that outputs a sequence of clock pulses corresponding to the pulse width of the pulse signal; 11
3 is a counting circuit, 3a is a synchronization signal synchronized with the rotation of the plane reflecting mirror 3, and 12 is a synchronization circuit that inputs this synchronization signal 3a and outputs a window pulse 12a for setting the field of view. In the above configuration, the field of view in the scanning direction is set by a synchronous signal 3a generated by a disc with a slit (not shown) and a photo interrupter (not shown) mounted coaxially with the plane reflecting mirror 3. 12 by setting the width of the wind pulse 12a, and utilizing the relationship that the width of the waveform of the output signal of the detection element 4 obtained by scanning the field of view with the plane reflecting mirror 3 is approximately proportional to the number of people to be measured. and multiplexer 10
The number of clock pulses output from the sensor is counted to measure the number of people within the field of view. Note that FIG. 1 shows only one channel with one sensing element 4, and the other channels are omitted.

By the way, in the above-mentioned crowding degree detection device, in order to obtain a wide field of view in a direction perpendicular to the scanning direction, a plurality of infrared detection elements are used side by side, and the field of view is divided to form a multi-channel configuration. At this time, since the infrared sensing elements are individually housed in cases such as the TO-5 type, it is physically impossible to make the distance between the sensing elements zero, resulting in gaps in the field of view between each channel. This situation is shown in FIG. 2, taking the case of three channels as an example. In the figure, 4a to 4c are infrared detection elements, A
is the crowding detection surface, A ₁ is the field of view of the first channel corresponding to the detection element 4a, A ₂ and A ₃ are the field of view of the second and third channels corresponding to the detection elements 4b and 4c, and A ₀ is the field of view. Holes and other parts that are the same as those in FIG. 1 are indicated by the same reference numerals. In order to minimize this field-of-view gap, increasing the number of sensing elements and arranging them at narrow intervals requires as many sensing elements and signal processing circuits such as amplifiers as the number of channels, making the device larger and more expensive. I become confused.

The present invention has been made in view of the above points, and it is an object of the present invention to utilize the defocus of an optical system to provide a wide detection field of view with a minimum number of infrared detecting elements and no missing parts of the field of view.

[Means to solve the problem]

The feature of the present invention is that in the congestion level detection device as shown in FIG. Place multiple pieces in
Further, the spacing between the infrared sensing elements is adjusted so that adjacent parts of the fields of view corresponding to the sensing elements overlap.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a diagram illustrating how the field of view is expanded due to the out-of-focus of the optical system, where a shows the case where the blur is not used, and b shows the case where the blur is used. In the figure, La to Lc are point light sources, Ma to Mc are their imaging points, a is the distance between the crowding level detection surface A and the condensing lens 2, b is the distance between the condensing lens 2 and the imaging plane B, k is the distance between the imaging plane B and the detection element position p, r is the radius of the condenser lens, and l is the amount of field expansion. In addition, the third
In the figure, it is assumed that the image formation formula 1/a+1/b=1/f (1) (where f is the focal length of the condenser lens 2) holds true.

In FIG. 3a, light emitted from a point light source La passes through a condenser lens 2 and forms an image at an imaging point Ma. Therefore, when a dot-like sensing element is placed at the imaging point Ma, its field of view on the detection surface A becomes a dot-like field of view at the position La.

On the other hand, if a point-shaped detection element is placed at a point p behind the imaging plane B by k as shown in FIG.
Images are formed at imaging points Mb and Mc, and a part of the imaged light is further incident on a point p where the detection element is located. That is, by placing the dot-like sensing element by k behind the imaging plane B, the field of view can be expanded from a dot-like field of view to a field of view with a width of 2l. Here, if the distance between the imaging points Mb and Mc is 2m, m=b/al...(2) ^m _k =r/b+k...(3) From this, the field of view expansion amount l is l=a/b× rk/b+k...(4). In the above example, the sensing element is placed after the imaging plane, but the same effect can be obtained even if it is placed in front of the imaging plane.

Next, the relationship between the mounting position of the detection element and the center position of the field of view of the channel will be explained with reference to FIG. Fourth
In the figure, h is the vertical distance from the center of lens 2 to crowding detection surface A, N is the vertical distance from the center of lens 2 to detection element mounting surface C (corresponding to b+k in Figure 3), and α is the vertical distance of the detection element. The mounting position, x is the visual field center position at that time, and x ₀ is the visual field center position when α=0. From Figure 4, α=Ntanθ ₁ =Nsinθ ₁ /cosθ ₁ ……(5) By rearranging these, α=Nh(x−x ₀ )/h ² +x ₀ x (8) is obtained. Here, N and h are determined by the specifications of the detection device, and therefore, if x is determined, the position α of the detection element can be found. Also, from equation (8), x = Nhx ₀ + αh ² /Nh - αx ₀ ... (9) If the diameter of the element is 2Δα, the width of the field of view x _w is x _w = Nhx ₀ + (α ±Δα)h ² /Nh−(α±Δα)x ₀ ……(1
0).

FIG. 5 is a diagram illustrating an example where the field of view is divided into three channels, where S is the required planar field of view, S ₁ to _{S 3} are the fields of view of the first to third channels, respectively, and X ₁ , X ₀ and X ₂ are the visual field centers of each channel, respectively. In this case, the detection element mounting positions α ₁ to _{α 3} of each channel are X ₁ , X ₀ or
Obtained by substituting X ₂ for X in the above formula (8),
Also, the field of view width can be obtained from equation (10). Here, the width of the field of view can be expanded by adjusting the distance N as described above by utilizing the blur of the lens, and it is possible to eliminate missing parts of the field of view.

By the way, when using the blur of the optical system, the field of view is expanded, but the detection resolution is reduced. Furthermore, when using blur, the field of view is expanded, but the optical gain within the field of view is maximum at the center of the field of view and decreases at the periphery. To prevent this, the optical gain can be made constant at each field point by determining the spacing of the sensing elements so that adjacent portions of the field of view of each channel overlap.

In addition, when designing the optical system, the number of channels, that is, the number of detection elements, their spacing, and their front and rear positions with respect to the lens (blurring level) should be determined by the mounting height of the crowding detection device,
It may be determined based on the required resolution, the width of the field of view, etc., so that there is no omission of the field of view.

〔Effect of the invention〕

As described above, according to the present invention, the plurality of detection elements are not placed on the imaging plane of the condenser lens, but are placed on a surface a predetermined distance before or after the imaging plane in a direction perpendicular to the scanning direction. In this way, the blurring of the optical system is utilized, and the resulting decrease in optical gain is compensated for by adjusting the spacing of each sensing element so that adjacent parts of each field of view corresponding to each sensing element overlap, Since the field of view of the sensing element is expanded, it is possible to eliminate the field of view and to minimize the number of sensing elements and signal processing circuits, that is, to provide an economical configuration.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the overall configuration of the congestion level detection device.
Figure 2 is a diagram showing the arrangement of the detection element and the state of field omission, Figure 3 is a diagram explaining the expansion of the field of view due to defocusing of the optical system, and Figure 4 is the mounting position of the detection element and the center position of the field of view of the channel. Diagram showing the relationship between
The figure is a diagram showing an example of division of the field of view. 1... Optical system housing case, 2... Condensing lens,
3...Flat reflecting mirror, 4, 4a, ~4c...detection element, A...crowding level detection surface, _A1 to _A3 ...field of view of each channel, _A0 ...out of field of view, B...result image plane,
La~Lc...point light source, Ma~Mc...imaging point, a...
...Distance between the lens and the crowding detection surface, b...Distance between the lens and the imaging surface, k...Distance between the imaging surface and the detection element, l...Amount of field of view expansion.

Claims (1)

[Scope of Claims] 1. A condensing lens that condenses infrared rays emitted from objects within a field of view, a scanning mirror that rotates at a constant cycle, and changes in the infrared rays incident through the condensing lens and the scanning mirror. an infrared detection element that outputs a signal according to the rotation of the scanning mirror, a synchronization circuit that generates a wind pulse for setting the field of view in the scanning direction of the infrared detection element in synchronization with the rotation of the scanning mirror, and an output signal of the infrared detection element. , a circuit that extracts only the signal having a predetermined value or more within the field of view set by the wind pulse, and a circuit that determines the number of people or the degree of crowding within the field of view from the waveform width of the signal having the predetermined value or more. In the degree detection device, a plurality of the infrared detection elements are arranged in a direction perpendicular to the scanning direction on a surface a predetermined distance before or after the imaging plane of the condenser lens, and each field of view corresponds to each of the detection elements. 1. A method for arranging elements of a congestion degree detection device, characterized in that the distance between the infrared detection elements is adjusted so that adjacent parts of the elements overlap.