JP2007315991A - Object detection sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To install an object detection sensor that can narrow a detection area and also has high detection sensitivity. <P>SOLUTION: Light from a light emitting element 1 is projected forward through a slit 10. The irradiation range of this light emission is narrowed by the slit 10. The irradiation range is a region surrounded by the innermost side (light emitting element 2 side) surface (a), the outermost side surface (b), the uppermost side surface (c), and the lowermost side surface (d). When an object to be detected exists in this region, a reflected light occurs. Light having passed the slit 20, of the reflected light, is received by the light emitting element 2. Of the reflected light, light that has passed the slit 20 and can be received by the light emitting element 2 is within the range surrounded by the innermost side surface (e) and the outermost side surface (f). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an object detection sensor for detecting an object such as a human body, and in particular, a light emitting element that emits light toward a detected object, a light receiving element that receives reflected light from the detected object, and the light emitting element and The present invention relates to an object detection sensor including a slit disposed on the front side of a light receiving element.

A conventional example of this type of object detection sensor is disclosed in Japanese Utility Model Laid-Open No. 5-87538. The slit of the same number consists of a rectangular cut-out hole (opening) formed in a plate material (directivity control plate) disposed on the front side of the light emitting element and the light receiving element. By installing this directivity control plate with slits, the detection area can be narrowed (paragraph 0017 of the same publication).
Japanese Utility Model Publication No. 5-87538

  The slit described in Japanese Utility Model Laid-Open No. 5-87538 is composed of a single rectangular hole (opening) formed by hollowing out a plate material having a predetermined thickness. In such a slit, when the opening is made small in order to narrow the detection area, both the light amount projected on the detected object and the light amount incident on the light receiving element from the detected object are reduced, and the detection sensitivity is lowered. .

  An object of the present invention is to install an object detection sensor that can narrow a detection area and also has good detection sensitivity.

  An object detection sensor according to the present invention (Claim 1) is provided with a light emitting element that emits light toward a detected object, a light receiving element that receives reflected light from the detected object, and a front side of the light emitting element. A light-emitting slit, and the light-emitting element and the light-receiving element are arranged so that each optical axis is included in the same plane (hereinafter referred to as an optical axis plane). Is characterized by comprising a plurality of plates that are substantially perpendicular to the optical axis plane and that extend in a direction substantially parallel to the optical axis direction of the light emitting element.

  The object detection sensor according to claim 2 is a light emitting element that emits light toward the object to be detected, a light receiving element that receives reflected light from the object to be detected, and a light receiving side slit disposed on a front side of the light receiving element. In the object detection sensor, the light-emitting element and the light-receiving element are arranged so that each optical axis is included in the same plane (hereinafter referred to as an optical axis plane). It is characterized by comprising a plurality of plates that are substantially perpendicular to the axial surface and extend in a direction substantially parallel to the optical axis direction of the light emitting element.

  An object detection sensor according to a third aspect of the present invention is the object detection sensor according to the first aspect, further comprising a light receiving side slit disposed on a front surface of the light receiving element, the light receiving side slit being connected to the optical axis surface. It is characterized by comprising a plurality of plates that are substantially vertical and extend in a direction substantially parallel to the optical axis direction of the light receiving element.

  According to a fourth aspect of the present invention, the object detection sensor according to the first or third aspect is characterized in that the plates of the light emitting side slits are substantially parallel to each other.

  According to a fifth aspect of the present invention, the object detection sensor according to the second or third aspect is characterized in that the plates of the light receiving side slit are substantially parallel to each other.

  The object detection sensor according to claim 6 is the object detection sensor according to claim 1 or 3, wherein the plate of the light emitting side slit is substantially parallel to each other except the plate on the most light receiving element side, and the plate on the most light receiving element side is from the light emitting element. It arrange | positions so that it may separate from an adjacent plate, so that it isolate | separates.

  The object detection sensor according to claim 7 is the object detection sensor according to claim 2 or 3, wherein the plate of the light receiving side slit is substantially parallel to each other except for the plate closest to the light emitting element, and the plate closest to the light emitting element is separated from the light receiving element. It arrange | positions so that it may separate from an adjacent plate, so that it isolate | separates.

  An object detection sensor according to an eighth aspect of the present invention is the object detection sensor according to any one of the first, third, fourth, and sixth aspects, wherein each plate of the light emitting side slit is oriented so as to be closer to the light receiving element as being separated from the light emitting element. It is characterized by this.

  The object detection sensor according to a ninth aspect of the present invention is the object detection sensor according to any one of the second, third, fifth, and seventh aspects, wherein each plate of the light receiving side slit is oriented so as to be closer to the light emitting element as being separated from the light receiving element. It is characterized by this.

  An object detection sensor according to a tenth aspect of the present invention is the object detection sensor according to any one of the first to ninth aspects, wherein each of the slits includes a connecting plate that connects side edges of the plates in a direction parallel to the optical axis surface. It is what.

  In the object detection sensor according to the first aspect of the present invention, the light emission side slit disposed on the front surface side of the light emitting element has a plurality of plates. Light from the light emitting element is projected between the plates and onto the object to be detected. For this reason, by increasing the number of plates or reducing the distance between the plates, the projection area can be narrowed without significantly reducing the amount of light projected.

  Moreover, in the 2nd aspect of this invention, the light-receiving side slit arrange | positioned at the front side of a light receiving element has several plates. The reflected light from the object to be detected passes between the plates and is received by the light receiving element. For this reason, by increasing the number of plates or reducing the distance between the plates, the detection area can be narrowed without significantly reducing the amount of received light.

  In the present invention, the plates of the light emitting side slits may be substantially parallel to each other, or the plates of the light receiving side slits may be substantially parallel to each other, thereby narrowing the detection area and increasing the projection light amount and the received light amount. Can do.

  In the present invention, the light emitting side slit plates are substantially parallel to each other except the light receiving element side plate, and the light receiving element side plates are separated from the adjacent plates as they are separated from the light emitting elements. It is good also as the structure arrange | positioned, By this, the projection light from a light emitting element can be widely projected to the light receiving element side.

  In the present invention, the plates of the light receiving side slits are substantially parallel to each other except for the plate closest to the light emitting element, and the plates closest to the light emitting element are arranged so as to be separated from the adjacent plates as they are separated from the light receiving element. Therefore, the detection area by the light receiving element can be expanded to the light emitting element side.

  In the present invention, each plate of the light emitting side slit is oriented so as to be closer to the light receiving element as it is separated from the light emitting element, and each plate of the light receiving side slit is oriented so as to be on the light emitting element side as it is separated from the light receiving element. It is preferable. Thereby, a detection area | region can be made close to a sensor.

  In the present invention, each slit preferably has a connection plate in which side edges in a direction substantially parallel to the optical axis surface of each plate are connected to each other. Thereby, the detection area can be narrowed also in the direction perpendicular to the optical axis plane.

The object detection sensor of the present invention has the following effects.
(1) The detection range is limited, and the color difference of the detection target can be reduced.
(2) It is possible to eliminate detection of an object to be detected at an unnecessary long distance or short distance.
(3) The light projecting direction and the light receiving direction can be configured not to be limited to the vertical direction (the vertical direction in FIG. 1B described later), and the amount of light can be increased.
(4) There are a plurality of optical paths as compared with a single slit, and the amount of light increases.
(5) It is insensitive to the three-dimensional misalignment between the light emitting element and the light receiving element and the slit, and the tolerance is large.
(6) The slit is not required to be designed and manufactured with a complicated and high accuracy like a lens, and can be optically designed and controlled relatively easily and inexpensively.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 shows an object detection sensor according to an embodiment, where (a) is a horizontal sectional view, and (b) is a side view (viewed along the line BB in FIG. 1 (a)). (C) is a perspective view showing the slit 10 on the light emitting element side.

  The object detection sensor includes a light emitting element 1 that projects light toward a detected object such as a human body, a light receiving element 2 that receives reflected light from the detected object, and a light emitting element disposed on the front side of the light emitting element 1. It has a side slit 10 and a light receiving side slit 20 arranged on the front side of the light receiving element 2.

  Both the light emitting element 1 and the light receiving element 2 have their optical axes in the plane of FIG. 1 (a) and substantially parallel to the optical axis direction. In this embodiment, the paper surface of FIG. 1 (a) is the optical axis surface.

  The light emitting side slit 10 includes a plurality of (11 in this embodiment) plates 11, 12, 13, 14, and 15 perpendicular to the optical axis plane, and parallel to the optical axis plane of each of the plates 11 to 15. It has the top plate 16 as a connection plate which connects one side edge (upper edge of FIG.1 (c)), and the bottom plate 17 as a connection plate which connects the other side edge (lower edge).

  Each plate 11-15 is rectangular shape, and is arrange | positioned substantially parallel mutually.

  In this specification, “substantially parallel” means that the extended surfaces of the plates are parallel so that they do not intersect at all, or the crossing angle between the extended surfaces is less than 3 °.

  The top plate 16 and the bottom plate 17 are substantially parallel to each other, and are substantially perpendicular to the plates 11 to 15. Note that “substantially perpendicular” means that the crossing angle is in the range of 87 to 93 °.

  The top plate 16 and the bottom plate 17 are parallelograms having one inner angle θ of about 70 to 89 °.

  The light emission side slit 10 is installed so that it may become the light receiving element 2 side, so that each plate 11-15 is separated from the light emitting element 1. FIG.

  Although the light receiving side slit 20 is omitted from the perspective view, the light receiving side slit 20 is symmetrical to the light emitting side slit 10. The light-receiving side slit 20 also includes plates 21 to 25, a top plate (not shown) that connects the upper edges of the plates 21 to 25, and a bottom plate (not shown) that connects the lower edges of the plates 21 to 25. And have. The light receiving side slit 20 is installed so that the plates 21 to 25 are closer to the light emitting element 1 as the plates 21 to 25 are separated from the light receiving element 2.

  In the object detection sensor configured as described above, the light from the light emitting element 1 is projected forward through the slit 10. The emission range of this light emission is narrowed by the slit 10. This irradiation range is an area surrounded by the innermost surface (light receiving element 2 side) surface a, the outermost surface b, the uppermost surface c, and the lowermost surface d. is there. When a detected object exists in this area, reflected light is generated. The reflected light that has passed through the slit 20 is received by the light receiving element 2. The reflected light that passes through the slit 20 and can be received by the light receiving element 2 is a range surrounded by the innermost surface e and the outermost surface f. Therefore, geometrically, a spatial region surrounded by these surfaces a to f is a detectable region. However, since the amount of light decreases as the distance from each of the elements 1 and 2 increases, a detected object farther than the vicinity indicated by E in the figure is not detected (note that E varies depending on the color and gloss of the detected object). . Therefore, a region surrounded by the surfaces a to f and closer to the elements 1 and 2 than E is a detection region. Dots are attached to this detection area.

  In the above embodiment, the plates 11 to 15 are substantially parallel to each other, and the plates 21 to 25 are substantially parallel to each other. However, the present invention is not limited to this, and is the innermost as shown in FIG. The side plate 11 may be inclined toward the light receiving element 2 side. Further, the innermost plate 21 may be inclined toward the light emitting element 1. That is, the distance between the plate 11 and the adjacent plate 12 increases as the distance from the light emitting element 1 increases. Further, the distance between the plate 21 and the adjacent plate 22 increases as the distance from the light receiving element 2 increases. In this case, it is preferable that the crossing angle of the extension surfaces of the plates 11 and 12 and the crossing angle of the extension surfaces of the plates 21 and 22 are both 3 to 60 °.

  According to the object detection sensor provided with the slits 10 'and 20' in FIG. 2, the light receiving / emitting characteristics are restricted to be wider (for example, sensitivity is made closer) or narrower (the sensitivity is concentrated in a specific area). Is possible. As a result, it is possible to determine a sensor area having a wider range and desired sensitivity. In practice, it is effective to provide sensitivity at a short distance.

  In the present invention, when the distance from the elements 1 and 2 to the nearest detection region is D, the length L in the optical path direction of the slits 10 and 20 is preferably about 20 to 50% of D. In the case of a human body detection sensor for a faucet or toilet, the distance W between the parallel plates 11 to 15 is preferably about 20 to 50% of L.

  The thickness of the plates 11 to 15 and 21 to 25 is preferably as thin as possible within the range having the strength and durability required as a slit. The slit is preferably made of synthetic resin. When the slit is manufactured by injection molding, the thickness of the plate is practically about 0.1 to 0.5 mm.

  The inner surface of the slit is preferably black. In addition, the inner surface of the slit may be roughened or flocked to suppress light reflection.

  An LED is suitable as the light emitting element. In the illustrated embodiment, one slit is arranged on the front side of one light emitting element, but a plurality of light emitting elements are arranged with the light emitting direction in the same direction, and one slit is arranged in front of them. A slit may be arranged. However, the number of light emitting elements is preferably as small as possible in order to reduce costs.

  As the light receiving element, a photodiode, a phototransistor, or the like is preferable. As for the light receiving element, one slit may be provided for one light receiving element, or a plurality of light receiving elements and one slit may be combined.

  In the present invention, a light converging lens, a reflecting mirror, or the like may be disposed between the light emitting element and the slit or between the light receiving element and the slit. Thereby, the ability of light emission or condensing improves and the loss of light decreases. For this reason, since the optical SN ratio is improved, it is possible to create a sensor that is resistant to noise and has a long detection distance with a simple circuit.

  In the present invention, it is preferable that the optical axis of the light emitting element and the optical axis of the light receiving element intersect as far as possible in order to increase sensitivity in the distance. The distance from the light emitting element or the light receiving element to the intersection of the optical axes is practically about 2 to 20 times the distance between the light emitting element and the light receiving element.

  In the above-described embodiment, there is a difference in the amount of reflected light such that the amount of reflected light is larger at the crossing side between the surfaces e and a and the amount of reflected light is smaller at the intersecting side between the surfaces f and b. In order to reduce this reflected light amount difference as much as possible, the distance between the plates 11 to 15 may be increased as the distance from the light emitting element increases, and the distance between the plates 21 to 25 may be increased as the distance from the light receiving element increases.

  In the above-described embodiment, each of the light-emitting side slit 10 and the light-receiving side slit 20 includes a plurality of plates 11 to 15 and 21 to 25. However, only one of the slits is applied. The other slit may have a configuration other than this.

It is explanatory drawing of embodiment. It is explanatory drawing of another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting element 2 Light receiving element 10 Light emitting side slit 11-15 Plate 16 Top plate 17 Bottom plate 20 Light receiving side slit 21-25 Plate

Claims (10)

A light emitting element that emits light toward the object to be detected, a light receiving element that receives reflected light from the object to be detected, and a light emitting side slit disposed on the front side of the light emitting element,
In the object detection sensor, the light emitting element and the light receiving element are arranged so that each optical axis is included in the same plane (hereinafter referred to as an optical axis plane).
The light emitting side slit includes a plurality of plates that are substantially perpendicular to the optical axis plane and extend in a direction substantially parallel to the optical axis direction of the light emitting element. A light emitting element that emits light toward the object to be detected, a light receiving element that receives reflected light from the object to be detected, and a light receiving side slit disposed on the front side of the light receiving element,
In the object detection sensor, the light emitting element and the light receiving element are arranged so that each optical axis is included in the same plane (hereinafter referred to as an optical axis plane).
The light receiving side slit comprises a plurality of plates that are substantially perpendicular to the optical axis surface and extend in a direction substantially parallel to the optical axis direction of the light emitting element. In Claim 1, the object detection sensor further includes a light receiving side slit disposed in front of the light receiving element,
The light receiving side slit includes a plurality of plates that are substantially perpendicular to the optical axis surface and extend in a direction substantially parallel to the optical axis direction of the light receiving element.   4. The object detection sensor according to claim 1, wherein the plates of the light emitting side slits are substantially parallel to each other.   4. The object detection sensor according to claim 2, wherein the plates of the light receiving side slit are substantially parallel to each other.   5. The light emitting side slit plate according to claim 1, wherein the light emitting side slit plates are substantially parallel to each other except for the light receiving element side plate, and the farthest light receiving element side plate is separated from the adjacent plate as the distance from the light emitting element is increased. An object detection sensor characterized by being arranged so as to.   4. The light receiving side slit plate according to claim 2, wherein the light receiving side slit plates are substantially parallel to each other except for the light emitting element side plate, and the farthest light emitting element side plates are separated from the adjacent plates as they are separated from the light receiving elements. An object detection sensor characterized by being arranged so as to.   7. The object detection sensor according to claim 1, wherein each plate of the light emitting side slit is oriented so as to be closer to the light receiving element as being separated from the light emitting element.   8. The object detection sensor according to claim 2, wherein each plate of the light receiving side slit is oriented so as to be closer to the light emitting element as being separated from the light receiving element. 9.   10. The object detection sensor according to claim 1, wherein each of the slits includes a connecting plate that connects side edges of each plate in a direction parallel to the optical axis surface.

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