JPH0567418A - Optical sensor - Google Patents

Abstract

PURPOSE:To eliminate influence of disturbance light by using a lens to provide a light shielding part having a small aperture in the vicinity of a focal plane thereof. CONSTITUTION:A light shielding part 4 having an aperture equivalent to a light converging spot is provided in the vicinity of a focal plane of a light receiving lens 3. With this constitution, only light within a narrow angular range can reach a light receiving element 5 so that malfunction due to disturbance light can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical sensor having a light emitting element and a light receiving element for detecting light reflected from an object.

[0002]

2. Description of the Related Art Conventionally, for example, in an automatic door or the like, in order to detect the arrival of a person in front of the door, light is emitted from a light emitting element such as an LED and an object enters the reach of the light. When it arrives, a moving object detector that detects that a moving object has entered a predetermined area is incorporated by using an optical sensor that detects light reflected from the object by a photodiode or the like.

[0003]

However, since such a conventional optical sensor has a broad light receiving sensitivity directivity of the light receiving element, it has a problem that it is easy to receive ambient light and thus the detection distance is short. Was.

In order to solve such a problem, it is an object of the present invention to eliminate the influence of ambient light by using a lens and providing a light shielding portion having a small opening near the focal plane thereof.

[0005]

In order to solve such a problem, the first invention is that the light emitted from the light emitting portion is reflected by an object and is focused by the light receiving lens and detected by the light receiving element. In the optical sensor described above, a light shielding portion having an opening sufficiently smaller than the lens aperture is provided between the lens and the light receiving element and near the focal plane of the lens. A second invention is characterized in that, in the first invention, the light emitting section is configured such that the light output from the light emitting element is output through a light projecting lens. A third invention is characterized in that, in the first invention or the second invention, the light receiving element is optically sealed so that light other than light passing through the opening of the light shielding portion does not reach. A fourth invention is characterized in that, in the first invention to the third invention, the light projecting lens and the light receiving lens are integrally formed. A fifth invention is characterized in that, in the first invention to the fourth invention, the light shielding portion has a plurality of openings. A sixth invention is characterized in that a plurality of light receiving elements are provided in the fifth invention. The seventh invention is
In the first invention to the sixth invention, a plurality of light-receiving lenses are provided. An eighth invention is characterized in that, in the first to seventh inventions, at least one mounting angle of the light projecting element, the light receiving element, the light projecting lens, and the light receiving lens is variable. A ninth invention is characterized in that, in the first invention to the eighth invention, at least one of the light projecting lens and the light receiving lens is composed of an unequal interval diffraction grating provided on a transparent flat plate.

[0006]

In the optical sensor having the above structure, the extraneous light in the unnecessary portion is eliminated by the light shielding portion having the opening sufficiently smaller than the lens aperture.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of an optical sensor of the present invention, in which reference numeral 1 denotes a light emitting element such as an LD or SLD that emits light having high emission energy, and the light generated there is passed through a light projecting lens 2. Is irradiated to the outside. At this time, the positional relationship between the light emitting element 1 and the light projecting lens 2 determines whether the light emitted from the light emitting element 1 is collimated or focused.

Reference numeral 3 denotes a light-receiving lens which focuses light entering the lens, and which has a light-shielding portion near the focal plane of the light-receiving lens 3 and which has an opening of the same size as the focal spot of the lens. 4 is provided, and only the light passing through the opening of the light shielding portion 4 reaches the light receiving element 5.

In this example, the light receiving element 5 is provided at a position deviated from the optical axis of the light receiving lens 3, and therefore, of the light emitted to the outside of the casing 6 through the light projecting lens 2, Reflected light is obtained when a moving object comes to the shaded portion. As can be seen from FIG. 1, this range is very deep, and therefore, the distance range that can be detected by this configuration is large.

As described above, since the light-shielding portion 4 having the opening of the same size as the focal spot is provided in the vicinity of the focal plane position of the light-receiving lens 2, the calculation basis is omitted, but the lens diameter and the focus are omitted. When the distances are 4.6 mm, the focused spot diameter 2w is 2.1 μm. Assuming that the thickness of the light shielding portion 4 is ignored and the aperture diameter is 2w, assuming that the amount of light reaching the light receiving element 5 is halved when the focal position of the lens deviates by w on the focal plane, the light receiving relative sensitivity The light receiving angle θ at which 50% becomes 50% is 0.013 °.

Therefore, by providing such a light-shielding portion 4, only the input light in an extremely narrow range can be received, so that the directivity becomes sharp and the disturbance light is less likely to be disturbed.

2 and 3 show an example in which the optical axis of the light receiving lens 3 and the center of the aperture of the light shielding portion 4 are aligned. Figure 4
Is designed to take in the light reaching the light receiving element 5 only through the opening of the light shielding portion 4, and since it is possible to prevent the interference due to the scattered light in the housing 6, the influence of the ambient light becomes more difficult.

FIGS. 5 (a) to 5 (f) show a structure in which the light projecting lens and the light receiving lens are integrally formed, which makes the mounting easy. FIG. 6 shows the one provided with a plurality of openings,
FIG. 7 shows that a plurality of light receiving elements are provided, and FIG. 8 shows that a plurality of light receiving lenses and light receiving elements are provided.

FIG. 9 shows the position and inclination of at least one of the light projecting element 1, the light receiving element 5, the light shielding portion 4, the light projecting lens 2 and the light receiving lens 3 which are variable. Can be received most efficiently. In the example of FIG. 9, the light emitting element 1 and the light projecting lens 2 are collectively configured to form one light projecting unit 10, and the light receiving lens 3, the light shielding portion 5, and the light receiving element 5 are collectively configured to be one light receiving unit 11. The light receiving unit 11 can be rotated by the angle setting shaft 12 to facilitate the adjustment.

[0015]

As described above, in the optical sensor according to the present invention, since the light-shielding portion having the opening of the same size as the focused spot of the lens is provided in the vicinity of the focal plane position of the light receiving lens, the directivity is improved. Since it can be sharpened, it is less susceptible to the influence of ambient light and has the effect of making it less likely to cause malfunction.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a fourth exemplary embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a fifth exemplary embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a sixth exemplary embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a seventh exemplary embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of an eighth embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a ninth embodiment of the present invention.

[Explanation of symbols]

 1 Light-Emitting Element 2 Light-Emitting Lens 3 Light-Receiving Lens 4 Light-Shielding Part 5 Light-Receiving Element 6 Body 10 Light-Emitting Unit 11 Light-Receiving Unit 12 Angle Setting Axis

Claims (9)

[Claims] 1. An optical sensor in which light output from a light-emitting portion is reflected by an object and focused by a light-receiving lens and detected by a light-receiving element, wherein the light-receiving element is between the lens and the light-receiving element and on the focal plane of the lens. An optical sensor characterized in that a light-shielding portion having an opening sufficiently smaller than a lens aperture is provided in the vicinity. 2. The optical sensor according to claim 1, wherein the light emitting section has a configuration in which light output from the light emitting element is output via a light projecting lens. 3. The optical sensor according to claim 1 or 2, wherein the light receiving element is optically sealed so that light other than light passing through the opening of the light shielding portion does not reach. 4. An optical sensor according to claim 1, wherein the light projecting lens and the light receiving lens are integrally formed. 5. An optical sensor according to claim 1, wherein the light shielding portion has a plurality of openings. 6. The optical sensor according to claim 5, wherein a plurality of light receiving elements are provided. 7. An optical sensor according to claim 1, wherein a plurality of light receiving lenses are provided. 8. The optical sensor according to claim 1, wherein the mounting angle of at least one of the light projecting element, the light receiving element, the light projecting lens, and the light receiving lens is variable. 9. The optical sensor according to claim 1, wherein at least one of the light projecting lens and the light receiving lens comprises an unequal-spaced diffraction grating provided on a transparent flat plate.