JP2001250979A - Optical sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a conventional optical sensor causes misdetection as if an object to be detected were in a detection object area although there is no object in the area since part of the light from a light emitting element is repeatedly reflected by the top and reverse surfaces of a transparent cover, propagates in the transparent cover, and made incident on a light receiving element 93 if a drop of water or dirt sticks on the top surface of the transparent cover. SOLUTION: The optical sensor 1 has couples of light emitting elements 3 and light receiving elements 4 arranged in a case 2, having an opening in the front, across a light shield wall 2a and is equipped with the transparent cover 9 in front of those light emitting element 3 and light receiving elements 4; and the transparent cover 9 is provided with a light absorbing member 11 in contact with the top or reverse surface of a part positioned above the light shield wall 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical sensor for detecting the presence or absence of an object such as a person or an object in a detection area, a distance to the object, and the like. The light emitted from the light emitting element is reflected by the object to be detected, and the reflected light is received by the light receiving element to detect the presence or absence of the object, the distance to the object, and the like. The present invention relates to an optical sensor of the type.

[0002]

2. Description of the Related Art As an example of this type of conventional optical sensor 90, for example, it is configured as shown in FIG.
A pair of a light emitting element 92 and a light receiving element 93 are disposed on a substrate 94 within a light-shielding wall 91a. Light emitting element 9
An LED or the like is used as 2, and a photodiode, a phototransistor or the like is used as the light receiving element 93. Condensing lenses 95 and 96 are provided in front of the light emitting element 92 and the light receiving element 93, respectively. The light emitted from the light emitting element 92 is condensed by the lens 95 and irradiated toward the detection target area. When an object is present in the detection target area, the light reflected by the object is condensed by a lens 96 and received by a light receiving element 93 to detect the presence or absence of an object and a distance. Is what you do. Reference numeral 97 denotes the light emitting element 92 and the light receiving element 9
3 is an integrated circuit for driving and signal processing, and is mounted on the same substrate 94 as the light emitting element 92 and the light receiving element 93.

[0005] Reference numeral 98 in FIG. 5 denotes a transparent cover provided in front of the light emitting element 92 and the light receiving element 93 so as to cover the opening of the case 91. This is provided to prevent intrusion of dust and the like. Note that the light emitting element 92
As a filter having a characteristic of selectively transmitting the emission wavelength range. In this case, the transparent cover 98 selectively transmits only the light in the wavelength region emitted from the light emitting element 92, and when an object is present in the detection target area, selectively reflects only the light reflected from the object. And the light receiving element 93 receives the light, thereby preventing malfunction due to disturbance light such as sunlight.

Reference numeral 99 denotes a transparent cover 98 and a light shielding wall 91a.
The elastic member is provided between the transparent cover 98 and the light-shielding wall 91a. The rectangular member is formed of an elastic material such as rubber along the upper surface of the light-shielding wall 91a so that stray light does not enter the gap between the transparent cover 98 and the light-shielding wall 91a. Is formed.

[0005]

However, in the case of such a conventional optical sensor 90, when water droplets and dirt 100 adhere to the surface of the transparent cover 98 as shown in FIG. The light is reflected without being emitted from the front surface of the transparent cover 98, and further reflected on the back surface of the transparent cover 98, and is repeatedly reflected on the front surface and the back surface of the transparent cover 98, so that light propagates inside the transparent cover 98. Would. An elastic member 99 is provided above the light shielding wall 91a. The elastic member 99 shields light leaking from a gap between the transparent cover 98 and the light shielding wall 91a, and propagates in the transparent cover 98. It is not possible to block even light. The light propagating in the transparent cover 98 thus finally enters the light receiving element 93 and is erroneously detected as if there is no object in the detection target area. And the solution of this point is an issue.

[0006]

According to the present invention, as a specific means for solving the above-mentioned conventional problems, a pair of light-emitting elements and a light-receiving element are arranged in a case having an opening on the front face with a light-shielding wall interposed therebetween. And a light sensor having a transparent cover in front of the light emitting element and the light receiving element,
An object of the present invention is to solve the problem by providing an optical sensor, wherein a light absorbing member is provided in close contact with a surface or a back surface of a portion located above the light shielding wall in the transparent cover.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail based on an embodiment shown in the drawings.

In FIG. 1, reference numeral 1 denotes an optical sensor according to the present invention. In this optical sensor 1, a pair of a light emitting element 3 and a light receiving element 4 are provided in a case 2 with a light shielding wall 2a therebetween.
It is arranged above. As the light emitting element 3, an LED or the like is used, and as the light receiving element 4, a photodiode, a phototransistor, or the like is used. Condensing lenses 6 and 7 are provided in front of the light emitting element 3 and the light receiving element 4, respectively. The light emitted from the light emitting element 3 is condensed by the lens 6 and emitted toward the detection target area. When an object is present in the detection target area, the light reflected by the object is condensed by a lens 7 and received by a light receiving element 4 to detect the presence or absence of the object. is there. Reference numeral 8 denotes an integrated circuit for driving the light emitting element 3 and the light receiving element 4 and for processing the signal.
And the light receiving element 4 is mounted on the same substrate 5.

Reference numeral 9 in FIG. 1 denotes a transparent cover provided in front of the light emitting element 3 and the light receiving element 4 so as to cover the opening of the case 2. This is provided to prevent intrusion of dust and the like. Note that a function as a filter having a characteristic of selectively transmitting the emission wavelength region of the light emitting element 3 is provided as needed. In this case, the transparent cover 9 selectively transmits only light in the wavelength region emitted from the light emitting element 3,
When an object to be detected exists in the detection target area, only the light reflected from the object to be detected is selectively transmitted and received by the light receiving element 4, so that a malfunction due to disturbance light such as sunlight is prevented. I have.

Reference numeral 10 denotes a transparent cover 9 and a light shielding wall 2.
and a rectangular member made of an elastic material such as rubber along the upper surface of the light shielding wall 2a so that stray light does not enter through a gap between the transparent cover 9 and the light shielding wall 2a. It is formed in a column shape.

In the present invention, up to this point, in the present invention, a light absorbing member 11 such as a black tape is attached to the rear surface of the transparent cover 9 at a portion located above the light shielding wall 2a by means of bonding or the like. It is stuck closely. Thus, as shown in FIG. 2, when the dirt 12 adheres to the surface of the transparent cover 9, even if the light emitted from the light emitting element 3 propagates repeatedly in the transparent cover 9, the light is absorbed. Since the light is absorbed by the portion where the member 11 is attached, the light does not propagate any more, and such light does not accidentally enter the light receiving element 4.

The portion to which the light absorbing member 11 is attached is the elastic member 10 above the light shielding wall 2a other than the light receiving / emitting path.
Between the light absorbing member 1 and the transparent cover 9.
There is no effect on the light receiving and emitting by attaching 1.

Although the light absorbing member 11 is provided on the back side of the transparent cover 9, it may be provided on the front side of a portion located above the light shielding wall 2a.

In the above embodiment, the light absorbing member 11
Has been described with an example in which a black tape is adhered and adhered by adhesion. However, the present invention is not limited to this, and a silicone-based black rubber having an adhesive force may be adhered, and in this case, an elastic member is used. 10 and the light absorbing member 11 can be shared.

In addition, as the light absorbing member 11,
A film having a light absorbing effect may be formed by means such as coating or vapor deposition. In addition, various members and means having a light absorbing effect can be selected as necessary.

Further, as in the second embodiment shown in FIG. 3, the light absorbing member 11 may be integrally formed in a portion of the transparent cover 9 located above the light shielding wall 2a, and the same as in the first embodiment. The effect is obtained. In this case, for example, a transparent resin forming the transparent cover 9 and a black resin forming the light absorbing member 11 can be obtained by means of two-color molding.

Further, as in the third embodiment shown in FIG. 4, the light absorbing member 11 is not provided in a portion of the transparent cover 9 located above the light shielding wall 2a, and a V-shaped notch groove 13 is formed in the light shielding wall 2a. It may be formed along. In this case, the light that has propagated inside the transparent cover 9 is not absorbed as in the first and second embodiments, but is transmitted through the cutout groove 13 so as not to be further reflected. ,
A similar effect can be obtained in that the propagation of light in the transparent cover 9 is prevented.

The cut-out groove 13 may be on either the front surface or the back surface of the transparent cover 9 as long as it is located above the light shielding wall 2a. For example, when it is desired to reduce the thickness of the groove 9, a plurality of small notches 13 may be formed due to a problem of strength. further,
A plurality may be alternately formed on the front surface and the back surface. Further, the cutout groove 13 is not limited to the V-shape, but may be a U-shape or a concave shape.

[0019]

As described above, according to the optical sensor of the present invention, a pair of light-emitting elements and a light-receiving element are arranged in a case having an opening on the front face with a light-shielding wall interposed therebetween.
A transparent cover is provided in front of the light emitting element and the light receiving element, and the light absorbing member is provided in close contact with the front surface or the back surface of the portion located above the light shielding wall with respect to the transparent cover, Even if water droplets and dirt adhere to the surface of the transparent cover and part of the light from the light emitting element repeatedly reflects on the front and back surfaces of the transparent cover and propagates inside the transparent cover, the light absorbing member is stuck. Since the light is absorbed by the part, the light does not propagate any more, so that such light does not accidentally enter the light receiving element and malfunction does not occur. It has an extremely excellent effect.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of an optical sensor according to the present invention.

FIG. 2 is an explanatory diagram showing a light receiving and emitting state when dirt adheres to the surface of a transparent cover of the optical sensor of the present invention.

FIG. 3 is a cross-sectional view showing a second embodiment of the optical sensor according to the present invention.

FIG. 4 is a sectional view showing a third embodiment of the optical sensor according to the present invention.

FIG. 5 is a sectional view showing a conventional example.

FIG. 6 is an explanatory diagram showing a light receiving and emitting state when dirt adheres to the surface of a transparent cover of a conventional optical sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical sensor 2 ... Case 2a ... Shielding wall 3 ... Light emitting element 4 ... Light receiving element 5 ... Substrate 6 ... Light emitting element side lens 7 ... Light receiving element side lens 8 ... Circuit element 9 ... Transparent cover 10 Elastic member 11 Light absorbing member 12 Dirt 13 Notch groove

Continued on the front page (72) Inventor Mitsuaki Misugi 2-9-13-1 Nakameguro, Meguro-ku, Tokyo Inside Stanley Electric Co., Ltd. (72) Takaaki Fujii 2-9-13-1 Nakameguro, Meguro-ku, Tokyo Stanley F term (reference) in Electric Co., Ltd. 2F065 AA00 AA06 CC16 DD11 GG07 GG12 JJ01 JJ15 JJ18 PP22 UU02 5F089 BB02 CA04 DA15

Claims (3)

[Claims] 1. An optical sensor comprising: a pair of light-emitting elements and a light-receiving element disposed in a case having an opening on a front surface with a light-shielding wall interposed therebetween; and a transparent cover in front of the light-emitting element and the light-receiving element. 3. The optical sensor according to claim 1, wherein the transparent cover is provided with a light absorbing member in close contact with a surface or a back surface of a portion located above the light shielding wall. 2. A light sensor comprising: a pair of light-emitting elements and a light-receiving element disposed in a case having an opening on a front surface with a light-shielding wall interposed therebetween; and a transparent cover in front of the light-emitting element and the light-receiving element. 3. The optical sensor according to claim 1, wherein a light absorbing member is formed integrally with the transparent cover at a portion located above the light shielding wall. 3. An optical sensor having a pair of light-emitting elements and a light-receiving element disposed in a case having an opening on a front surface with a light-shielding wall interposed therebetween, and having a transparent cover in front of the light-emitting elements and the light-receiving elements. 3. The optical sensor according to claim 1, wherein the transparent cover has a cutout groove formed in at least one of a front surface and a back surface of a portion located above the light shielding wall.