JP3090337B2 - Optical detector - Google Patents

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 and detecting infrared rays emitted from a predetermined detection area.

[0002]

2. Description of the Related Art There is an optical detection device used to detect whether a person is in a predetermined area and to turn on a lighting device when a person is present. in this case,
When constructing a passive type using infrared rays emitted by the human body, it is necessary to judge whether the heat source is moving,
This will lead to misperception.

For this reason, in this type of detecting device, the number of light receiving elements (pyroelectric elements) as light receiving means is reduced in order to generate a large number of actual detection ranges in the detection area. In order to be able to do this, the configuration shown in FIG. 11 or FIG. 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, and a light receiving element 1 composed of a pyroelectric element. Is to be constant. The latter uses 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, oblique incident light having an angle with respect to the optical axis is used. In this case, however, the problem of "blur" due to the aberration of the lens is associated. . 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 incident on the light receiving element decreases. To
In addition to causing a decrease in sensitivity, when a twin element using a differential output by two elements is used as an infrared detection element to improve environmental resistance and disturbance resistance,
Since the outputs cancel each other out at the portion where the two detection beams generated by the two elements overlap each other, the sensitivity is more significantly reduced.

In the latter case, incident light from an arbitrary direction can be collected without aberration. However, since the distance RO between the lens and the detection surface varies depending on the position of the lens, the size of the detection beam increases as it goes to the periphery. It gets bigger. This makes it difficult to efficiently detect a human body by its movement. There is a mirror using a multi-segment mirror in which a parabolic mirror is combined. In this case, the effect of "blur" is small, and since the reflectivity is usually 90% or more, light can be efficiently collected. However, there is a problem that the optical system becomes large.

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

[0007]

According to the present invention, there is provided a multi-segment 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. Wherein each lens is formed such that the first surface is a plane, the second surface is a hyperboloid, and the rotation axis of the hyperboloid of the second surface is oblique to the plane of the first surface. Angle between the axis of rotation and the normal to the plane of the first surface
Degree θ, the incident light reaching the focal point through the vertex of the lens
The angle formed by the notation line is δ, the vertex of the lens and the center of the light receiving element
L, focal length f, refraction of lens material
When the ratio is n, δ = arctan (L / f) θ = arcsin (sinδ / n) , and 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. Then, it is characterized in that it is arranged in a grid at intervals of 1 to 2 times the size of the detection target on the detection surface, and that the polarities of adjacent detection beams are inverted.

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

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the illustrated embodiment. This detecting device detects the movement of an object emitting infrared rays and outputs an output. As shown in FIG. It consists of a system, an infrared detector, an amplifier, a determiner, and an output. The condensing optical system includes a flat multi-segment lens 2 in which a plurality of lenses are combined on one plane, the light receiving element 1 including a pyroelectric element as an infrared detecting element, and the amplifying unit includes: Fig. 5
As shown in the figure, there is a center frequency of 1 Hz, and low-frequency components are cut in order to suppress fluctuations due to temperature changes in the surrounding environment and wind, and unnecessary high-frequency components are also cut in order to prevent electromagnetic noise. Uses things that get lost. The center frequency is set to 1 Hz because, as described later, the movement of the hand of the human body in the speed range of 0.1 to 0.5 m / s can be detected efficiently. . The judging section is configured to output the output to the output section when the output level of the amplifying section exceeds the threshold level.

In this case, the light receiving element 1 is a third light receiving element.
As shown in the figure, a structure in which four light receiving units 11 are arranged in a lattice pattern and connected with the illustrated polarity is used. The output is one output. The multi-segment lens 2 includes the 1 shown in FIG.
A lens in which five lenses 20 are arranged in three rows of five on one plane is used. Each lens 20 here is shown in FIG.
As shown in the figure, the first surface is a plane 21 and the second surface is a hyperboloid 22
The rotation axis C of the hyperboloid 22
Is different from a normal single lens having no aberration coincident with the normal H direction of the plane 21 of the first surface, the normal H of the plane 21 of the first surface and the rotation axis C of the hyperboloid 22 of the second surface are different from each other. It forms an angle θ. The focal point F of the lens 20 is located on the rotation axis C and away from the normal H, and the incident light P reaching the focal point F through the vertex O of the lens 2 is And the incident light P is converged on the focal point F without aberration. When the angle θ is increased, the angle δ between the incident light P condensed at the focal point F with no aberration and the normal H to the plane 10 of the first surface also increases. Further, considering a single lens having a constant peripheral edge thickness, such a lens 20 has an elliptical shape as shown in FIG.

In the multi-segment lens 2 shown in FIG. 2, the fifteen lenses 20 having different angles δ are arranged on the detection surface 3 so that the detection beam 4 is arranged as shown in FIG.
The detection beams 4 are combined so that the sizes of the detection beams 4 on the detection surface 3 are the same, and the polarities of the adjacent detection beams 4 are different. However, here, the detecting device is the one shown in FIG.
As shown in FIG. 0, the detection area A is assumed to be attached to one end of a sink lamp 6 installed above the sink 5 to control the lighting of the sink lamp 6. Is set to be asymmetrical to match the lighting range, and in recent kitchens, there are many cases where the front of the sink 5 is a counter, and in addition, it is sometimes used by being inverted. The front and rear are symmetrical.

That is, when the center of the light receiving element 1 is X and the vertices of the lenses 20 in the multi-segment lens 2 are O _{1 to} O ₁₅ , these arrangements are as shown in FIG. When the arrangement is determined in this way, each lens 20
Are overlapped as shown in FIG. 9, and the area of each lens 20 is distributed in consideration of the following points. That is,
Assuming that the area of the lens 20 is S, and the angle between the main optical axis (rotation axis C) and the normal H of the first surface 21 that is a plane is θ, the power PW of light incident from the detection surface 3 is PW = k・ S · cos ⁴ θ (k: proportional constant), so that sensitivity (power PW) in the detection area A
So that the lens 20 having a larger angle θ
The area S is set to be large. However, since the lenses 20 having vertices of O ₄ , O ₅ , O ₉ , O ₁₀ , O ₁₄ , and O ₁₅ have many overlapping portions, the area of the lenses 20 in the central row (vertices of O ₉ , O ₁₀ ) is reduced. It is made smaller and the area of the remaining lens 20 is made larger. This is determined in consideration of the actual use conditions. When the human body works in the detection area A, the detection beam 4 in the center row is always applied to the detection beam 4 by the lens 20 in the end row when the human body works in the detection area A. For,
This is because the movement of the human body can be detected more efficiently if the sensitivity of the detection beam 4 by the lens 20 in the end row is increased.
When the distance between the vertex O of the lens 20 and the center X of the light receiving element 1 is L, the focal point F passes through the vertex O of the lens 2.
The angle δ that the incident light P makes with respect to the normal H is δ = arctan (L / f) (f: focal length) , and n × sin θ = sin δ (n: (Refractive index) , the angle θ is determined by θ = arcsin (sin δ / n) . The angle θ is determined from the positional relationship with the light receiving element 1, and the shape of the hyperboloid is determined.

By the way, such a flat type multi-segment lens 2 can be manufactured at low cost by injection molding of a polyethylene resin. In this case, the transmittance of the infrared ray emitted from the human body near the center wavelength of 10 μm is 1 mm in thickness. 40%
Therefore, it is necessary to reduce the thickness of the lens 20. For this reason, it is conceivable to use a Fresnel lens. However, when a Fresnel lens is used, the wall thickness changes greatly, so that when cooled and solidified after injection molding, a time shift occurs in the cooling method, so-called “hike”. Is generated on the surface, and local irregularities are generated on the lens surface, and sufficient accuracy cannot be obtained. For this reason, each lens 20 is not a Fresnel lens here.

However, due to the above-mentioned transmittance, as shown in FIG. 8 (c), the minimum thickness t ₀ is set to the minimum value 0 which is allowable in terms of the fluidity of the resin during molding. .3 mm, the maximum and minimum thickness difference Δt that affects the securing of the effective lens area
Is set to 0.5 mm, which is the minimum value necessary for securing the lens area required for use in the sink light 6, and the maximum thickness t is suppressed to 1 mm or less. In addition, the "hike"
The problem of inevitably arises because there is a thickness difference,
Since the change in wall thickness is gradual, the degree of occurrence of sink marks is small, and the allowable error is about 20 times larger in the infrared region than in the case of visible light. It does not occur on the surface.

The light receiving element 1 and the multi-segment lens 2
In this case, a total of 4 × 15 detection beams 4 are generated. In addition to the fact that the size of each detection beam 4 on the detection surface 3 is equal, the detection of each detection beam 4 The intervals on the surface 3 are also the same so that the detection capabilities at various points in the detection area A are the same. Here, as the detection target, a hand extended on the sink 5 is assumed.
Since it is 150 mm, the size of the detection beam 4 is set so that one side is about 70 mm, and the interval between the detection beams 4 is about 160 mm, that is, approximately equal to the size of the hand of the human body. . This is because the efficiency is highest when the interval between the detection beams 4 is 1 to 2 times the size of the detection target.

[0016]

As described above, the present invention comprises a multi-segment lens in which a plurality of lenses having substantially the same focal position are combined on one plane, and light receiving means disposed at the focal position. The first surface of each lens is flat,
The second surface is a hyperboloid, and the rotation axis of the hyperboloid of the second surface is formed as oblique to the plane of the first surface, and the rotation axis and the normal to the plane of the first surface. The angle made
θ, the incident light reaching the focal point through the vertex of the lens
Δ, the angle between the line and the vertex of the lens and the center of the light receiving element
L is the distance between the lenses, f is the focal length, and the refractive index of the lens material is
When n, δ = arctan (L / f) θ = arcsin (sinδ / n) , and 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. Each lens which is arranged in a grid pattern at intervals of 1 to 2 times the size of the detection target on the detection surface, and in which the polarities of adjacent detection beams are inverted, constitutes a multi-segment lens However, even if the lens is not directed in the required direction, it is possible to efficiently collect light from this direction without aberration, and this lens is combined on one plane to form a multi-segment lens. The focal length of each lens is set so that the detection beam from each lens is approximately the same size on the detection surface, and The detection beam from each lens is detected. Since the detection beams are arranged in a grid at intervals of 1 to 2 times the size of the detection target on the known surface and the polarities of the adjacent detection beams are inverted, detection of the detection target within the detection area is performed by each unit. It can be performed evenly and very efficiently.

[Brief description of the drawings]

FIGS. 1A and 1B show a detection area and an arrangement of detection beams according to an embodiment of the present invention, wherein FIG. 1A is a front view and FIG. 1B is a plan view.

FIG. 2 shows a specific example of the multi-segment lens according to the first embodiment (a).
Is a front view, and (b) is a bottom view.

FIGS. 3A and 3B show a specific example of the above light receiving element, wherein FIG. 3A is a front view and FIG. 3B is a side view.

FIG. 4 is a block diagram showing the same.

FIG. 5 is a characteristic diagram of the amplifier unit according to the first embodiment;

FIG. 6 is an explanatory diagram of a lens constituting the multi-segment lens according to the first embodiment.

FIGS. 7A and 7B are explanatory views of the shape of the above lens, and FIG.
(b) is a front view.

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

FIG. 9 is an explanatory diagram of an overlap of each lens in the 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.

11A and 11B show a conventional example, in which FIG. 11A is a perspective view and FIG. 11B 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]

 Reference Signs List 1 light receiving element 2 multi-segment lens 3 detection surface 4 detection beam

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-186801 (JP, A) JP-A-2-2344091 (JP, A) JP-A-1-118394 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) G01J 1/02-1/04 G01J 5/02 G01V 9/04 G08B 13/19-13/191

Claims (1)

(57) [Claims] 1. A multi-segment lens in which a plurality of lenses having substantially the same focal position are combined on one plane, and a light receiving means disposed at the focal position. The first surface is a plane, the second surface is a hyperboloid, and the rotation axis of the hyperboloid of the second surface is formed as oblique to the plane of the first surface. Plane
The angle between the normal of the lens and the focal point through the vertex of the lens
The angle between the incident light and the above normal is δ, the vertex of the lens
The distance between the lens and the center of the light receiving element is L, the focal length is f,
When the refractive index of the lens material is n, δ = arctan (L / f) θ = arcsin (sinδ / n) , and each lens is formed so that the detection beam by each lens has substantially the same size on the detection surface. Are set in a grid pattern at intervals of 1 to 2 times the size of the detection target on the detection surface, and the polarities of adjacent detection beams are inverted. Optical detection device.