JPH10172075A - Optical block for beam sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a protection cover from being melted or burnt even in the case that sunlight is made incident on the optical block for beam sensor and infrared rays of sunlight reflected by a parabolic mirror are converged on the protection cover. SOLUTION: A protection cover 7 is made of a material through which infrared rays are transmitted. Thus, even if sunlight is made incident and infrared rays of sunlight reflected by a parabolic mirror 2 are converged on a side face of the protection cover 7, the protection cover is prevented from being melted or burnt because these infrared rays are not absorbed by the protection cover 7 but are transmitted through. Further, a reflection layer which reflects infrared rays may be formed on the surface of the protection cover 7 or the protection cover 7 is made of a material having a high heat resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical block of a light emitter and a light receiver of a beam sensor.

[0002]

2. Description of the Related Art Conventionally, as one of systems for detecting an intruder, a beam sensor system in which a light emitter and a light receiver are arranged to face each other is known. The light emitter is provided with at least one light emitting optical block, and the light receiver is provided with the same number of light receiving optical blocks as the number of light emitting optical blocks, and the corresponding light emitting optical blocks and light receiving optical blocks are correctly opposed. Is installed as follows.

FIG. 1 shows a configuration example of a light receiving optical block.
FIG. 1 is an exploded perspective view of the light receiving optical block.
Is a housing, 2 is a parabolic mirror, 3 is a filter, 4 is an opening, 5 is a light receiving element, 6 is an element substrate, 7 is a protective cover, 8, 9, and 1.
0 indicates a locking portion.

A parabolic mirror 2 is formed on the inner surface of the housing 1. The filter 3 is made of a material that blocks visible light and transmits infrared light, at least near infrared light, such as a colored polycarbonate resin or acrylic resin. At a predetermined position of the filter 3, an opening 4 for inserting a light receiving element 5 having sensitivity to infrared rays and locking portions 8, 9, and 10 for engaging an element substrate 6 are provided.

[0005] The light receiving element 5 is mounted on an element substrate 6. Note that a circuit for driving the light receiving element 5 may be mounted on the element substrate 6. The protective cover 7 is for preventing dust from adhering to the element substrate 6, and is usually made of inexpensive AB for the purpose of cost reduction.
S resin (acrylonitrile butadiene styrene copolyme
r).

Attachment of the light receiving element 5 to the filter 3
The light receiving element 5 is inserted into the opening 4 of the filter 3 and the element substrate 6
Is locked to the locking portions 8, 9, 10. Then, a protective cover 7 is attached to the filter 3 so as to cover the element substrate 6. The attachment of the protective cover 7 to the filter 3 may be performed by an appropriate method.

When the filter 3 having the light receiving element 6 mounted thereon is mounted on the front surface of the housing 1, the assembly of the light receiving optical block as shown in FIG. 2 is completed. The attachment of the filter 3 to the housing 1 may be performed by a well-known appropriate method. It should be noted that the light receiving element 5 is naturally located at the focal point of the parabolic mirror 2 in an assembled state as shown in FIG.

FIG. 3 is a sectional view taken along the line AA 'of FIG. 2. Since the light receiving element 5 is disposed at the focal point of the parabolic mirror 2 as described above, the light receiving element 5 is moved from the opposing light projecting optical block. The emitted substantially parallel rays of infrared light are reflected by the parabolic mirror 2 and converge on the light receiving element 5 as shown in FIG.

Although the structure of the light receiving optical block has been described above, the light projecting optical block has the same structure.
That is, in the configuration shown in FIG. 1, if a light emitting element that emits infrared light is used instead of the light receiving element 5, a light projecting optical block can be obtained. Of course, since the light emitting element is configured to be located at the position of the focal point of the parabolic mirror, the infrared light emitted from the light emitting element is obtained by reversing the arrow in the ray diagram of FIG. The light is projected toward the light receiving optical block.

[0010]

However, depending on the installation condition of the light receiving optical block, sunlight may enter the light receiving optical block, and depending on the incident angle of the sunlight at that time, the parabolic mirror 2 may be used. It has been found that the reflected infrared rays of sunlight may converge on the side surface of the protective cover 7 as shown in FIG. 4, and in that case, the protective cover 7 may melt.

If the protective cover 7 melts and flows out, the surroundings are adversely affected and the function may be impaired. In particular, when the ABS resin that has melted and flowed out of the protective cover 7 adheres to the element substrate 6, the function as the light receiving optical block may be impaired.

Further, if the protective cover 7 is melted to form a hole, dust may enter through the hole. Furthermore, when the intensity of the infrared rays of the incident sunlight is very strong, it is possible that the protective cover 7 may burn out. It is clear that the above problem is the same for the light projecting optical block.

The present invention solves the above-mentioned problems, and sunlight enters the light receiving optical block and the light projecting optical block, and the infrared rays of the sunlight reflected by the parabolic mirror converge on the protective cover. It is an object of the present invention to provide an optical block of a beam sensor that does not melt out or burn out even if it does.

[0014]

In order to achieve the above object, an optical block of a beam sensor according to claim 1 comprises:
A housing in which a parabolic mirror is formed on the inner surface, a filter disposed in front of the housing for blocking visible light, and a parabolic mirror formed on the inner surface of the housing, the filter being attached to the filter. In an optical block of a beam sensor including a light emitting element or a light receiving element disposed at a focal position and a protective cover attached to a filter so as to cover the light emitting element or the light receiving element, the protective cover is formed of a material that transmits infrared rays. It is characterized by having.

According to a second aspect of the present invention, there is provided an optical block for a beam sensor, comprising: a housing having a parabolic mirror formed on an inner surface thereof; a filter disposed on a front surface of the housing for blocking visible light; A light emitting element or a light receiving element disposed at a focal position of a parabolic mirror formed on the inner surface of the housing, and a protection cover attached to a filter so as to cover the light emitting element or the light receiving element. In the optical block of the sensor, a reflection layer that reflects infrared rays is formed on the surface of the protective cover.

Further, the optical block of the beam sensor according to the third aspect is a housing having a parabolic mirror formed on an inner surface thereof, a filter disposed on a front surface of the housing for blocking visible light, and attached to the filter. A light emitting element or a light receiving element disposed at a focal position of a parabolic mirror formed on the inner surface of the housing, and a protection cover attached to a filter so as to cover the light emitting element or the light receiving element. In the optical block of the sensor, the protective cover is formed of a material having high heat resistance.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical block of a beam sensor according to the present invention will be described below.

The structure of the optical block of the beam sensor according to the present invention is the same as that of the above-mentioned conventional light receiving optical block and light projecting optical block, but the material for forming the protective cover 7 is different.

It is considered that the above-mentioned problem occurs in the related art because the protective cover 7 is made of ABS resin and absorbs converged infrared rays of sunlight.

Therefore, if the protective cover 7 is formed of a material that transmits infrared rays, even if the infrared rays of sunlight reflected by the parabolic mirror 2 converge on the side surface of the protective cover 7 as shown in FIG. Since the infrared rays are transmitted without being absorbed by the protective cover 7, the protective cover 7 does not melt or burn as in the related art.

It is also effective to form a reflection layer for reflecting infrared rays on the surface of the protective cover 7. According to this configuration, even if the infrared rays of the sunlight reflected by the parabolic mirror 2 converge on the side surface of the protective cover 7 as shown in FIG. 4, the infrared rays are reflected by the surface of the protective cover 7 and dispersed. This is because the protection cover 7 can be prevented from melting or burning as in the related art.

Further, the protective cover 7 may be formed of a material having high heat resistance, for example, a laminate for forming the element substrate 6. That is, since the sunlight moves with time, the time when the infrared rays of the sunlight converge on the side surface of the protective cover 7 is short as shown in FIG. The problem described above can be avoided by using a heat-resistant material that does not melt or burn out while the infrared rays of sunlight are converging.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible. For example, various structures other than those shown in the drawings are known as the structure of the optical block of the beam sensor, but it is a matter of course that the present invention can be applied to those structures.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an optical block of a beam sensor.

FIG. 2 is a perspective view of an optical block of the assembled beam sensor.

FIG. 3 is a sectional view taken along line AA ′ of FIG. 2;

FIG. 4 is a diagram for explaining a problem of the optical block of the beam sensor according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Parabolic mirror, 3 ... Filter, 4 ... Opening, 5
... Light receiving element, 6 ... Element board, 7 ... Protective cover, 8, 9,
10. Locking part.

Claims (3)

[Claims] 1. A housing having a parabolic mirror formed on an inner surface thereof, a filter for blocking visible light disposed on a front surface of the housing, and a filter mounted on the inner surface of the housing. In the optical block of the beam sensor, which includes a light emitting element or a light receiving element arranged at the focal position of the parabolic mirror and a protective cover attached to a filter so as to cover the light emitting element or the light receiving element, the protective cover transmits infrared light. An optical block of a beam sensor, wherein the optical block is formed of a material that changes. 2. A housing having a parabolic mirror formed on an inner surface thereof, a filter disposed on a front surface of the housing for blocking visible light, and a filter mounted on the inner surface of the housing. In the optical block of the beam sensor including the light emitting element or the light receiving element arranged at the focal position of the parabolic mirror and the protective cover attached to the filter so as to cover the light emitting element or the light receiving element, the surface of the protective cover An optical block of a beam sensor, wherein a reflection layer that reflects infrared rays is formed. 3. A housing having a parabolic mirror formed on an inner surface thereof, a filter disposed on a front surface of the housing for blocking visible light, and attached to the filter, wherein the filter is formed on an inner surface of the housing. In the optical block of a beam sensor including a light emitting element or a light receiving element arranged at a focal position of a parabolic mirror and a protective cover attached to a filter so as to cover the light emitting element or the light receiving element, the protective cover has heat resistance. An optical block of a beam sensor, wherein the optical block is formed of a high material.