JPH05256695A - Optical detector - Google Patents

Abstract

PURPOSE:To make a passive type optical detector, detecting the presence of a human body, able to detect the human body so efficiently despite compact in size by receiving an infrared ray to be emitted out of a specified detecting range and detecting it for the end. CONSTITUTION:Each lens in multisplit lenses 2 where plural pieces of lenses- making each focal position to almost the same-are combined together on one plane is formed of the first plane into a flat surface, the second plane into a hyperboloid, and a turning shaft of this hyperboloid of the second plane is formed into such one as skewed to the flat surface of the first plane. In succession, each focal distance of these lenses is set up so as to make each detecting beam 4 of respective lenses become almost the same size on a detecting surface 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical detection device, and more particularly to a passive optical detection device for detecting the presence or absence of a human body by detecting infrared rays emitted from a predetermined detection area.

[0002]

2. Description of the Related Art There is an optical detection device used for detecting whether or not a person is present within a predetermined area and turning on a lighting device when the person is present. in this case,
When constructing a passive type that uses infrared rays emitted by the human body, it is necessary to judge whether the heat source is moving,
It will cause misunderstanding.

Therefore, in this type of detection device, in order to generate a large number of actual detection ranges in the detection area, the number of light receiving elements (pyroelectric elements) as light receiving means is reduced. In order to be able to do so, the form shown in FIG. 11 or 12 is used. The former is composed of a split lens 2 in which a plurality of lenses (Fresnel lenses) having the same focal length are combined with each other, and a light receiving element 1 including a pyroelectric element. Each lens is combined on one plane so that the image magnification is different in each part. It is designed to be constant at. In the latter, the multi-divided lens 2 is a dome lens in which each lens is provided on a hemisphere and the focal position of each lens coincides with the center of the hemisphere.

[0004]

In the former case, obliquely incident light having an angle with respect to the optical axis is used, but in this case, there is a problem of "blur" due to the aberration of the condenser lens. Hang on. This is particularly noticeable when a Fresnel lens is used, and when the detection beam spreads beyond a predetermined size due to "blur", the amount of infrared light that enters the light-receiving element decreases. Therefore, in addition to lowering the sensitivity, if a twin element using a differential output by two elements is used as an infrared detection element for improving the environmental resistance and the disturbance resistance, two elements are used. Since the outputs cancel each other at the portion where the two detection beams generated by the element overlap each other, the decrease in sensitivity becomes more remarkable.

In the latter case, incident light from any direction can be condensed without aberration, but since the distance RO between the lens and the detection surface differs depending on the position of the lens, the size of the detection beam becomes larger toward the periphery. It gets bigger. This makes it difficult to detect a human body efficiently by its movement. Although there is one using a multi-divided mirror in which a parabolic mirror is combined, in this case, the influence of "blur" is small, and the reflectance is usually 90% or more, so that the light can be condensed efficiently. However, there is a problem that the optical system becomes large.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a detection device which is small in size and can detect a human body efficiently.

[0007]

SUMMARY OF THE INVENTION In the present invention, however, a multi-divided lens in which a plurality of lenses having substantially the same focal position are combined on one plane, and a light receiving means arranged at the focal position are provided. Each lens is formed such that the first surface is a flat surface, the second surface is a hyperboloid, and the rotation axis of the hyperbolic surface of the second surface is oblique to the plane of the first surface. In addition, it is characterized in that the focal length of each lens is set so that the detection beam from each lens has substantially the same size on the detection surface.

According to the present invention, the size of the optical system does not become large, the sensitivity does not decrease due to the aberration of the lens, and the movement of the detection target on the detection surface can be detected reliably.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the illustrated embodiments. This detection device detects the movement of an object emitting infrared rays and outputs an output. As shown in FIG. It is composed of a system, an infrared detection element, an amplification section, a judgment section, and an output section. The condensing optical system is composed of a flat type multi-divided lens 2 in which a plurality of lenses are combined on one plane, the light receiving element 1 which is a pyroelectric element as an infrared detection element, and the amplification section is Figure 5 shows the frequency characteristics
As shown in Fig. 1, the center frequency is at 1 Hz, and low frequency components are cut to suppress fluctuations due to temperature changes in the surrounding environment and wind, and unnecessary high frequency components are also cut to prevent electromagnetic noise. It uses the one that ends up. The center frequency is set to 1 Hz so that the movement of the hand of the human body in the speed range of 0.1 to 0.5 m / s can be efficiently detected, as described later. .. The determination unit is configured to cause the output unit to output when the output level of the amplification unit exceeds the threshold level.

As the light receiving element 1 in FIG.
As shown in FIG. 4, the four light-receiving units 11 arranged in a grid pattern are connected with the polarities shown in the figure. The output is one output. The multi-segment lens 2 has a structure shown in FIG.
The lenses 20 are arranged in three rows of five lenses on one plane. As shown in FIG. 6, in each lens 20 here, the first surface is formed as a flat surface 21 and the second surface is formed as a hyperboloid surface 22, but the rotation axis C of the hyperboloid surface 22 is a flat surface of the first surface. Unlike a normal aberration-free single lens that coincides with the normal line H direction of 21, the normal line H of the flat surface 21 of the first surface and the rotation axis C of the hyperboloid surface 22 of the second surface form an angle θ. Is becoming The focal point F of the lens 20 is located on the rotation axis C and apart from the normal line H, and the incident light P reaching the focal point F through the apex O of the lens 2 reaches the normal line H.
The incident light P is focused on the focal point F with no aberration while forming an angle δ with respect to. When the angle θ is increased, the angle δ formed by the incident light P focused on the focal point F without aberration with the normal line H of the first surface 10 is also increased. Considering a single lens 20 having a constant peripheral edge thickness, the lens 20 has an elliptical shape as shown in FIG.

In the multi-divided lens 2 shown in FIG. 2, the detection beam 4 is arranged on the detection surface 3 of the fifteen lenses 20 having different angles .delta. As shown in FIG.
The detection beams 4 are combined so that the detection beams 4 on the detection surface 3 have the same size and the adjacent detection beams 4 have different polarities. However, here the detection device is
As shown in 0, the detection area A is assumed to be mounted on one end side of the sink light 6 installed above the sink 5 to control the lighting of the sink light 6. Is asymmetrical so as to match the certification range, and in many kitchens in recent years the front of the sink 5 is often a counter, and in addition, it may be used upside down. The front and back are symmetrical.

That is, when the center of the light receiving element 1 is X and the vertices of the respective lenses 20 in the multi-divided lens 2 are 01 to 015, these arrangements are as shown in FIG. When the arrangement is decided in this way, each lens 2
0 overlaps as shown in FIG. 9, but this allocates the area of each lens 20 in consideration of the following points. That is, if the area of the lens 20 is S and the angle formed by the normal line H of the first surface 21 whose main optical axis (rotation axis C) is a plane is θ,
Since the power PW of the light incident from the detection surface 3 is PW = k · S · cos ⁴ θ (k: proportional constant), the sensitivity (power PW) in the detection area A
So that the lens 20 has a larger angle θ,
The area S is made large. However, for the lenses 20 having vertices O ₄ , O ₅ , O ₉ , O ₁₀ , O ₁₄ , and O ₁₅ , there are many overlapping portions, so that the central row (vertex O
The area of the lens 20 of ( ₉ , O ₁₀ ) is reduced and the area of the remaining lens 20 is increased. This is determined in consideration of the actual use condition, and when the human body works in the detection area A, when it hits the detection beam 4 in the central row, it always hits the detection beam 4 by the lens 20 in the end row. For this reason, the movement of the human body can be detected more efficiently by increasing the sensitivity of the detection beam 4 by the lens 20 in the end row.
The value of the angle θ is determined by θ = arctan (L / f) (f: focal length), where L is the distance between the vertex O of the lens 20 and the center X of the light receiving element 1. The angle θ is determined from the positional relationship with the light receiving element 1, and the hyperboloid shape is determined.

By the way, such a flat type multi-divided lens 2 can be manufactured at a low cost by injection molding of polyethylene resin. In this case, the transmittance of infrared rays emitted by the human body in the vicinity of the central wavelength of 10 μm is 1 mm in thickness. 40%
Since it is not so good, it is necessary to reduce the thickness of the lens 20. For this reason, it is possible to use a Fresnel lens, but when a Fresnel lens is used, there is a large change in wall thickness, so there is a time lag in the cooling method when cooling and solidifying after injection molding, so-called "sink" Occurs on the surface and local unevenness is generated on the lens surface, so that sufficient accuracy cannot be obtained. Therefore, each lens 20 is not a Fresnel lens here.

However, because of the above-mentioned transmittance, as shown in FIG. 8 (c), the minimum wall thickness t ₀ is set to the minimum value allowed in terms of the fluidity of the resin during molding. 0.3 mm,
Maximum and minimum wall thickness difference Δ that affects securing of effective lens area
t is 0.5 mm, which is the minimum value required to secure the lens area required when using as the light source lamp 6.
The maximum wall thickness t is suppressed to 1 mm or less. Incidentally, the problem of the above-mentioned "sink" will inevitably occur as long as there is a difference in wall thickness, but since the change in wall thickness is gradual, the degree of occurrence of "sink" is small, and in the infrared region it is more Since the permissible error is increased by about 20 times, unevenness, which actually poses a problem, does not occur on the lens surface.

Then, the light receiving element 1 and the multi-divided lens 2
In combination with the above, a total of 4 × 15 detection beams 4 are generated. However, the detection beams 4 are not necessarily made to have the same size on the detection surface 3 and the detection beams 4 are detected. The intervals on the surface 3 are also set to be the same so that the detection ability is the same at various points in the detection area A. Here, the size of the hand is 100 to 100, because the hand to be detected is assumed to be the hand out on the sink 5.
Since it is 150 mm, the size of the detection beam 4 is set to be about 70 mm on one side, and the interval between the detection beams 4 is set to be about 160 mm, that is, substantially the same as the size of the human hand. .. This is because the efficiency is the highest when the interval between the detection beams 4 is 1 to 2 times the size of the detection target.

[0016]

As described above, according to the present invention, each lens constituting the multi-divided lens can efficiently collect light from this direction without aberration even if the lens is not directed in the required direction. It is possible, and because these lenses are combined on one plane to form a multi-divided lens, they are small and have excellent light-collecting efficiency, and the detection beam from each lens is on the detection surface. Since the focal lengths of the respective lenses are set to have substantially the same size, it is possible to uniformly and efficiently detect the detection target in the detection area.

[Brief description of drawings]

FIG. 1 is a front view and (b) is a plan view showing the arrangement of a detection area and a detection beam in one embodiment of the present invention.

FIG. 2 shows a specific example of the above multi-segment lens (a).
Is a front view and (b) is a bottom view.

FIG. 3 shows a specific example of the above light receiving element, (a) is a front view and (b) is a side view.

FIG. 4 is a block configuration diagram of the above.

FIG. 5 is a characteristic diagram of the amplification unit of the above.

FIG. 6 is an explanatory diagram of a lens forming the above multi-segment lens.

FIG. 7 (a) is a side view showing the shape of the above lens,
(b) is a front view.

FIG. 8 is an explanatory diagram of the arrangement and sectional shape of each lens in the above multi-segment lens.

FIG. 9 is an explanatory diagram of the overlap of each lens in the above multi-segment lens.

FIG. 10 shows an installation example and a detection area of the above,
(a) is a plan view, (b) is a front view, and (c) is a side view.

FIG. 11 shows a conventional example, (a) is a perspective view and (b) is an explanatory view.

FIG. 12 shows another conventional example, in which (a) is a sectional view,
(b) is an explanatory view.

[Explanation of symbols]

 1 light receiving element 2 multi-divided lens 3 detection surface 4 detection beam

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[Procedure amendment]

[Submission date] May 7, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

[0004]

In the former case, obliquely incident light having an angle with respect to the optical axis is used, but in this case, there is a problem of "blur" due to the aberration of the condenser lens. Hang on. This is especially noticeable when a Fresnel lens is used, and when the detection beam spreads beyond a certain size due to "blur", the amount of infrared light that enters the light receiving element decreases. To
In addition to reducing the sensitivity, if a twin element that uses a differential output of two elements is used as an infrared detection element in order to improve environmental resistance and disturbance resistance,
Since the outputs cancel each other at the overlapping portion of the two detection beams generated by the two elements, the decrease in sensitivity will be more remarkable.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

In the multi-divided lens 2 shown in FIG. 2, the detection beam 4 is arranged on the detection surface 3 of the fifteen lenses 20 having different angles .delta. As shown in FIG.
The detection beams 4 are combined so that the detection beams 4 on the detection surface 3 have the same size and the adjacent detection beams 4 have different polarities. However, here the detection device is
As shown in 0, the detection area A is assumed to be mounted on one end side of the sink light 6 installed above the sink 5 to control the lighting of the sink light 6. Is asymmetrical so as to match the lighting range, and in many kitchens in recent years, the front of the sink 5 is often a counter, and in addition, it may be used upside down. The front and back are symmetrical.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

That is, when the center of the light receiving element 1 is X and the vertices of the respective lenses 20 in the multi-divided lens 2 are 01 to 015, these arrangements are as shown in FIG. When the arrangement is decided in this way, each lens 2
0 overlaps as shown in FIG. 9, but this allocates the area of each lens 20 in consideration of the following points. That is, if the area of the lens 20 is S and the angle formed by the normal line H of the first surface 21 whose main optical axis (rotation axis C) is a plane is θ,
Since the power PW of the light incident from the detection surface 3 is PW = k · S · cos ⁴ θ (k: proportional constant), the sensitivity (power PW) in the detection area A
So that the lens 20 has a larger angle θ,
The area S is made large. However, for the lenses 20 having vertices O ₄ , O ₅ , O ₉ , O ₁₀ , O ₁₄ , and O ₁₅ , there are many overlapping portions, so that the central row (vertex O
The area of the lens 20 of ( ₉ , O ₁₀ ) is reduced and the area of the remaining lens 20 is increased. This is determined in consideration of the actual use conditions. When the human body works in the detection area A, when it hits the detection beam 4 in the central row, it always hits the detection beam 4 by the lens 20 in the end row. For this reason, the movement of the human body can be detected more efficiently by increasing the sensitivity of the detection beam 4 by the lens 20 in the end row.
The value of the angle θ is determined by δ = arctan (L / f) (f: focal length), where L is the distance between the vertex O of the lens 20 and the center X of the light receiving element 1. The angle θ is determined from the positional relationship with the light receiving element 1, and the hyperboloid shape is determined.

Claims (1)

[Claims] 1. A multi-divided lens in which a plurality of lenses having substantially the same focal position are combined on one plane, and a light receiving means arranged at the focal position, each lens comprising: The first surface is a flat surface, the second surface is a hyperboloid, and the rotation axis of the hyperbolic surface of the second surface is oblique to the plane of the first surface, and the detection beam by each lens is detected. The optical detection device is characterized in that the focal lengths of the respective lenses are set so that they have substantially the same size on the surface.