JP2011107019A - Photoelectric sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric sensor that can detect an object adjacent to a lens or also detect an object at the position away from the lens by adjusting the size of a dead zone. <P>SOLUTION: The optical axis 12a of a projection lens 12 is shifted to the side of a light receiving element 13 from the center 11a of the light emitting face of a projection element 11, so that a projection area A is made wider on the side of a light receiving lens 14. In addition, the optical axis 14a of a light receiving lens 14 is shifted to the side of the projection element 11 from the center 13a of the light sensitive face of the light receiving element 13, so that a light receiving visual field B is made wider on the side of the projection lens 12. Thus a dead zone C is made small. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a photoelectric sensor that receives reflected light of diffused light projected on a detection region and detects an object in the detection region.

Conventionally, a diffuse reflection type photoelectric sensor is used to detect the presence or absence of a detection target object in a detection region (see, for example, Patent Document 1).
FIG. 5 is a cross-sectional view showing a configuration of a conventional diffuse reflection photoelectric sensor 100. The diffuse reflection photoelectric sensor 100 includes a light projecting element 101 that projects light toward the detection area, a light projecting lens 102 that refracts the light projected from the light projecting element 101 and irradiates the light toward the detection area, and a detection area. A light receiving lens 104 that collects the light reflected by the detection target object, a light projecting lens 102 that receives the light collected by the light receiving lens 104, and a case 105 that accommodates these lenses. The case 105 holds the light projecting lens 102 and the light receiving lens 104 so that the optical axes 102a and 104a are parallel to each other. Further, the center 101a of the light emitting surface of the light projecting element 101 is aligned with the optical axis 102a of the light projecting lens 102, and the center 103a of the photosensitive surface of the light receiving element 103 is aligned with the optical axis 104a of the light receiving lens 104. Has been.

  In the case of the diffuse reflection type photoelectric sensor 100 shown in FIG. 5, the light projecting area A and the light receiving field B are determined based on the divergence angles of the light projecting lens 102 and the light receiving lens 104. The area to be detected is the detection range.

JP 2001-267625 A

  Since the conventional diffuse reflection type photoelectric sensor is configured as described above, as shown in FIG. 5, there is a non-intersecting region of the light projection region A and the light receiving field B, that is, the dead zone C, between the lenses 102 and 104. In this dead zone C, the detection target object cannot be detected. Then, since the size of the dead zone C is restricted by the size of the lenses 102 and 104, there is a problem that it is difficult to adjust.

  The present invention has been made to solve the above-described problems, and provides a photoelectric sensor capable of detecting an object in the vicinity of the lens or an object at a position away from the lens by adjusting the size of the dead zone. The purpose is to do.

  The photoelectric sensor according to claim 1 of the present invention is arranged such that the center of the light emitting surface of the light projecting element is shifted from the optical axis of the light projecting lens.

  According to a second aspect of the present invention, there is provided a photoelectric sensor in which the center of the photosensitive surface of the light receiving element is displaced from the optical axis of the light receiving lens.

  In the photoelectric sensor according to claim 3 of the present invention, the center of the light emitting surface of the light projecting element and the optical axis of the light projecting lens are shifted, and the center of the photosensitive surface of the light receiving element and the optical axis of the light receiving lens are shifted. Are arranged.

  According to a fourth aspect of the present invention, the optical axis of the light projecting lens is arranged so as to be shifted from the center of the light emitting surface of the light projecting element toward the light receiving element.

  The photoelectric sensor according to claim 5 of the present invention is arranged such that the center of the light emitting surface of the light projecting element is shifted from the optical axis of the light projecting lens toward the light receiving element.

  According to a sixth aspect of the present invention, the photoelectric sensor is arranged such that the optical axis of the light receiving lens is shifted from the center of the photosensitive surface of the light receiving element toward the light projecting element.

  According to a seventh aspect of the present invention, the center of the photosensitive surface of the light receiving element is arranged so as to be shifted from the optical axis of the light receiving lens toward the light projecting element.

  According to the first to third aspects of the present invention, the center of the light emitting surface of the light projecting element and the optical axis of the light projecting lens are shifted from each other, or the center of the photosensitive surface of the light receiving element and the optical axis of the light receiving lens. Since at least one of the two is shifted, the size of the dead zone is adjusted, and a photoelectric sensor capable of detecting an object in the vicinity of the lens or an object at a position away from the lens is provided. Can be provided.

  According to the invention of claim 4, since the optical axis of the light projecting lens is arranged to be shifted from the center of the light emitting surface of the light projecting element to the light receiving element side, the crossing position of the light projecting area and the light receiving field The dead zone can be reduced by moving the lens closer to the lens, and as a result, an object can be detected in the vicinity of the lens.

  According to the invention of claim 5, since the center of the light emitting surface of the light projecting element is arranged to be shifted to the light receiving element side from the optical axis of the light projecting lens, the crossing position of the light projecting area and the light receiving field The dead zone can be increased by moving the lens away from the lens, and as a result, an object can be detected at a position away from the lens.

  According to the sixth aspect of the present invention, the optical axis of the light receiving lens is arranged so as to be shifted from the center of the photosensitive surface of the light receiving element to the light projecting element side. The dead zone can be reduced close to the lens, and as a result, an object can be detected near the lens.

  According to the seventh aspect of the present invention, the center of the photosensitive surface of the light receiving element is arranged so as to be shifted from the optical axis of the light receiving lens toward the light projecting element side. The dead zone can be increased away from the lens, and as a result, the object can be detected at a position away from the lens.

It is sectional drawing which shows the structure of the diffuse reflection type photoelectric sensor 10 which concerns on Embodiment 1 of this invention. It is a top view which shows the structure of the diffuse reflection type photoelectric sensor 10 shown in FIG. 1, and shows 2 examples of Fig.2 (a) and FIG.2 (b). It is sectional drawing which shows the structure of the diffuse reflection type photoelectric sensor 10a which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure of the diffuse reflection type photoelectric sensor 10b which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the structure of the conventional diffuse reflection type photoelectric sensor.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing a configuration of a diffuse reflection photoelectric sensor 10 according to Embodiment 1 of the present invention. A diffuse reflection photoelectric sensor 10 shown in FIG. 1 includes a light projecting element 11 that projects light toward a detection area, and a light projection lens 12 that refracts the light projected from the light projecting element 11 and irradiates the light toward the detection area. The light receiving lens 14 condenses the light reflected on the detection target object in the detection area, the light receiving element 13 that receives the light collected by the light receiving lens 14, and a case 15 that houses them.

  The configuration of the control circuit that controls the light emission of the light projecting element 11 and the detection circuit that detects the amount of light received by the light receiving element 13 are the same as those of the conventional diffuse reflection photoelectric sensor described in Patent Document 1 and the like. Since it is good, illustration and description are omitted.

  In this example, a chip-type light emitting diode is used as the light projecting element 11, and its light emitting surface is directed to the light projecting lens 12. Further, a chip-type photodiode is used as the light receiving element 13, and its photosensitive surface is directed to the light receiving lens 14. Further, convex lenses are used as the light projecting lens 12 and the light receiving lens 14.

  The case 15 accommodates the light projecting element 11 and the light projecting lens 12, the light receiving element 13 and the light receiving lens 14 side by side, and holds the light projecting lens 12 and the light receiving lens 14 so that the optical axes 12a and 14a are parallel to each other. To do. In addition, the center 11a of the light emitting surface of the light projecting element 11 and the optical axis 12a of the light projecting lens 12 are shifted from each other, and the center 13a of the photosensitive surface of the light receiving element 13 and the optical axis 14a of the light receiving lens 14 are shifted. Are arranged.

When the optical axis 12 a of the light projecting lens 12 is shifted from the center 11 a of the light emitting surface of the light projecting element 11 in the direction of the light receiving element 13, the light projecting area A is moved to the light receiving lens 14 side by the inversion action of the light projecting lens 12. The dead zone C becomes smaller.
Similarly, when the optical axis 14 a of the light receiving lens 14 is shifted from the center 13 a of the photosensitive surface of the light receiving element 13 in the direction of the light projecting element 11, the light receiving field B is changed to the light projecting lens 12 by the inversion action of the light receiving lens 14. It spreads to the side and the dead zone C becomes smaller.
Accordingly, the crossing position of the light projecting area A and the light receiving field B is close to the diffuse reflection type photoelectric sensor 10 and the dead zone C is reduced, so that it is closer than the conventional diffuse reflection type photoelectric sensor 100 shown in FIG. The detection target object can be detected stably.

FIG. 2 is a view of the diffuse reflection photoelectric sensor 10 shown in FIG. 2 as viewed from the front side where the lenses 12 and 14 are installed, and shows two examples of FIGS. 2 (a) and 2 (b). As shown in FIG. 2A, when the light projecting lens 12 and the light receiving lens 14 are arranged side by side so as to be parallel to the longitudinal side of the front surface of the case 15, the center 11 a of the light emitting surface of the light projecting element 11, The optical axis 12 a of the light projecting lens 12, the center 13 a of the photosensitive surface of the light receiving element 13, and the optical axis 14 a of the light receiving lens 14 do not necessarily have to be aligned.
Further, as shown in FIG. 2B, even when the light projecting lens 12 and the light receiving lens 14 are arranged diagonally on the front surface of the case 15, the center 11 a of the light emitting surface of the light projecting element 11, the light projecting lens, and the like. The optical axis 12 a of 12, the center 13 a of the photosensitive surface of the light receiving element 13, and the optical axis 14 a of the light receiving lens 14 do not have to be aligned.

  Further, in the cross-sectional view in the side direction shown in FIG. 1, the optical axis 14a of the light receiving lens 14 is arranged to be shifted from the center 13a of the photosensitive surface of the light receiving element 13 toward the light projecting element 11. When viewed from the front direction shown in FIG. 2B, the optical axis 14a of the light receiving lens 14 is shifted from the center 13a of the photosensitive surface of the light receiving element 13 toward the light projecting element 11 as viewed diagonally. Well, the positional relationship in the left-right direction does not matter. Even if the optical axis 14a of the light receiving lens 14 is shifted from the center 13a of the photosensitive surface of the light receiving element 13 toward the light projecting element 11 in the horizontal positional relationship, the light of the light receiving lens 14 in the positional relationship viewed diagonally. It is only necessary that the shaft 14 a is shifted from the center 13 a of the photosensitive surface of the light receiving element 13 toward the light projecting element 11. The arrangement relationship between the light projecting element 11 and the light projecting lens 12 is the same.

  For convenience of explanation, it has been described that the optical axes 12 a and 14 a of the light projecting lens 12 and the light receiving lens 14 are shifted, but the center 11 a of the light emitting surface of the light projecting element 11 and the center 13 a of the photosensitive surface of the light receiving element 13. Needless to say, it may be shifted.

  As described above, according to the first embodiment, in the diffuse reflection type photoelectric sensor 10, the optical axis 12 a of the light projecting lens 12 is shifted from the center 11 a of the light emitting surface of the light projecting element 11 toward the light receiving element 13. In addition, the optical axis 14 a of the light receiving lens 14 is arranged so as to be shifted from the center 13 a of the photosensitive surface of the light receiving element 13 toward the light projecting element 11. For this reason, the position where the light projection area A of the light emitted from the light projection lens 12 intersects the light receiving field B of the light condensed on the light receiving lens 14 approaches the diffuse reflection type photoelectric sensor 10 and the object to be detected is close. Stable detection is possible even at a distance.

  In the first embodiment, the arrangement of the light projecting element 11 and the light projecting lens 12 and the arrangement of the light receiving element 13 and the light receiving lens 14 are both shifted. However, the present invention is not limited to this. Alternatively, only one of the arrangements may be shifted. For example, FIG. 3 shows a cross-sectional view of a diffuse reflection photoelectric sensor 10a having a configuration in which the arrangement of the light projecting element 11 and the light projecting lens 12 is shifted. In this case, even if the light receiving field B remains as it is, the light projecting area A spreads toward the light receiving lens 14 and the dead zone C becomes smaller, so that the detection target is closer to the conventional diffuse reflection photoelectric sensor 100 shown in FIG. An object can be detected.

  Also, contrary to the example of FIG. 3, the center 11 a of the light emitting surface of the light projecting element 11 and the optical axis 12 a of the light projecting lens 12 are arranged to coincide with each other, and the optical axis 14 a of the light receiving lens 14 is Even if it is shifted from the center 13a of the photosensitive surface in the direction of the light projecting element 11, the dead zone C becomes small, so that the object to be detected is located at a position closer to the conventional diffuse reflection photoelectric sensor 100 shown in FIG. Can be detected.

Embodiment 2. FIG.
4 is a cross-sectional view showing the configuration of a diffuse reflection photoelectric sensor 10b according to Embodiment 2 of the present invention. In FIG. 4, the same or corresponding parts as those in FIG. To do.

In the diffuse reflection photoelectric sensor 10 b shown in FIG. 4, when the center 11 a of the light emitting surface of the light projecting element 11 is shifted from the optical axis 12 a of the light projecting lens 12 toward the light receiving element 13, the light projecting lens 12 is inverted. As a result, the light projection area A spreads in the opposite direction to the light receiving lens 14 and the dead zone C becomes larger. In the example of FIG. 4, since the dead zone C is large, the intersecting region of the light projection region A and the light receiving field B is out of the illustrated range.
Similarly, when the center 13 a of the photosensitive surface of the light receiving element 13 is shifted from the optical axis 14 a of the light receiving lens 14 in the direction of the light projecting element 11, the light receiving field B is changed to the light projecting lens 12 by the inversion action of the light receiving lens 14. The dead zone C increases in the opposite direction.
Therefore, since the crossing position of the light projection area A and the light receiving field B moves away from the diffuse reflection type photoelectric sensor 10b and the dead zone C becomes larger, the detection is performed at a position farther than the conventional diffuse reflection type photoelectric sensor 100 shown in FIG. It is possible to detect the target object and not detect the detection target object at a close position.

  As described above, according to the second embodiment, in the diffuse reflection photoelectric sensor 10b, the center 11a of the light emitting surface of the light projecting element 11 is shifted from the optical axis 12a of the light projecting lens 12 toward the light receiving element 13 side. At the same time, the center 13 a of the photosensitive surface of the light receiving element 13 is arranged so as to be shifted from the optical axis 14 a of the light receiving lens 14 toward the light projecting element 11. For this reason, the position where the light projection area A of the light emitted from the light projection lens 12 intersects the light receiving field B of the light condensed on the light receiving lens 14 is away from the diffuse reflection type photoelectric sensor 10b, and is detected at a short distance. It is possible not to detect the target object.

  In the second embodiment, the arrangement of the light projecting element 11 and the light projecting lens 12 and the arrangement of the light receiving element 13 and the light receiving lens 14 are both shifted. However, the present invention is not limited to this. You may comprise so that only either one arrangement | positioning may be shifted. Even in the case of this configuration, the crossing position of the light projection area A and the light receiving field B moves away from the diffuse reflection type photoelectric sensor 10c and the dead zone C becomes large, so that the conventional diffuse reflection type photoelectric sensor 100 shown in FIG. In comparison with this, it is possible to detect the detection target object at a farther position and not detect the detection target object at a close position.

  In the first and second embodiments, a light emitting diode is used as the light projecting element 11 and a photodiode is used as the light receiving element 13. However, the present invention is not limited to this. In an arrangement using an optical fiber, the optical fiber optical axis for the light projecting element 11 and the optical axis 12a of the light projecting lens 12 are shifted, and the optical fiber optical axis for the light receiving element 13 and the optical axis 14a of the light receiving lens 14 are shifted. Even so, the same effect as in the first and second embodiments can be obtained.

  In the first and second embodiments, the arrangement of the light projecting element 11 and the light receiving element 13 is shifted. However, the present invention is not limited to this, and the light emitting surface of the light projecting element 11 and the photosensitivity of the light receiving element 13 are not limited thereto. The projection area A and the light receiving field B may be widened by enlarging the surface, or the light emitting surface of the light projecting element 11 and the photosensitive surface of the light receiving element 13 may be reduced to narrow the light projecting area A and the light receiving field B. You may make it do.

Further, when the light projecting element 11 is constituted by a plurality of (for example, two) elements, the light emitting surfaces of the plurality of elements are regarded as a single wide light emitting surface, and this is shifted from the optical axis 12 a of the light projecting lens 12. May be arranged. Similarly, when the light receiving element 12 is composed of a plurality of (for example, two) elements, the photosensitive surfaces of the plurality of elements are regarded as a single wide photosensitive surface, and this is shifted from the optical axis 14 a of the light receiving lens 14. You may make it the structure to arrange | position.
In particular, when the light projecting element 11 (or the light receiving element 12) is composed of two elements, the first element is aligned with the optical axis 12a of the light projecting lens 12 (or the optical axis 14a of the light receiving lens 14). By disposing and disposing the second element, the first element detects an object in the same detection range as before, and the second element is an object in a range closer or farther than the conventional detection range. Since detection can be performed, the detection range can be expanded.

  In the first and second embodiments, the diffuse reflection type photoelectric sensors 10, 10a, and 10b have been described as examples. However, the present invention is not limited to the diffuse reflection type, and may be applied to other reflection type photoelectric sensors. Good. For example, in the first and second embodiments, the center 11a of the light emitting surface of the light projecting element 11, the center 13a of the photosensitive surface of the light receiving element 13, the optical axis 12a of the light projecting lens 12, and the optical axis 14a of the light receiving lens 14 are parallel. Although the photoelectric sensor having a configuration in which the light emitting side and the light receiving side are arranged at an angle like the limited reflection type photoelectric sensor, the photoelectric sensor may be applied. .

DESCRIPTION OF SYMBOLS 10 Diffuse reflection type photoelectric sensor 11 Emitting element 11a Center of light-emitting surface 12 Projection lens 12a Optical axis 13 Light receiving element 13a Center of photosensitive surface 14 Light receiving lens 14a Optical axis 15 Case 100 Diffuse reflection type photoelectric sensor 101 Light emitting element 101a Light emission Center of surface 102 Emitting lens 102a Optical axis 103 Light receiving element 103a Center of photosensitive surface 104 Receiving lens 104a Optical axis 105 Case A Light emitting area B Light receiving field C Dead zone

Claims (7)

A light projecting element that projects light toward the detection area;
A light projection lens that refracts the light projected from the light projecting element and irradiates the light toward the detection region;
A light receiving lens for collecting the light reflected from the detection region;
A light receiving element that receives light collected by the light receiving lens;
In the photoelectric sensor that includes the light projecting element and the light projecting lens, the light receiving lens and the light receiving element arranged side by side, and a case that holds the light projecting lens and the light receiving lens.
A photoelectric sensor, wherein a center of a light emitting surface of the light projecting element and an optical axis of the light projecting lens are shifted from each other. A light projecting element that projects light toward the detection area;
A light projection lens that refracts the light projected from the light projecting element and irradiates the light toward the detection region;
A light receiving lens for collecting the light reflected from the detection region;
A light receiving element that receives light collected by the light receiving lens;
In the photoelectric sensor that includes the light projecting element and the light projecting lens, the light receiving lens and the light receiving element arranged side by side, and a case that holds the light projecting lens and the light receiving lens.
A photoelectric sensor, wherein a center of a photosensitive surface of the light receiving element and an optical axis of the light receiving lens are shifted from each other. A light projecting element that projects light toward the detection area;
A light projection lens that refracts the light projected from the light projecting element and irradiates the light toward the detection region;
A light receiving lens for collecting the light reflected from the detection region;
A light receiving element that receives light collected by the light receiving lens;
In the photoelectric sensor that includes the light projecting element and the light projecting lens, the light receiving lens and the light receiving element arranged side by side, and a case that holds the light projecting lens and the light receiving lens.
The center of the light emitting surface of the light projecting element and the optical axis of the light projecting lens are shifted from each other, and the center of the photosensitive surface of the light receiving element and the optical axis of the light receiving lens are shifted from each other. Photoelectric sensor.   4. The photoelectric sensor according to claim 1, wherein the optical axis of the light projecting lens is arranged to be shifted toward the light receiving element from the center of the light emitting surface of the light projecting element.   The photoelectric sensor according to claim 1 or 3, wherein the center of the light emitting surface of the light projecting element is arranged so as to be shifted to the light receiving element side from the optical axis of the light projecting lens.   4. The photoelectric sensor according to claim 2, wherein the optical axis of the light receiving lens is arranged to be shifted from the center of the photosensitive surface of the light receiving element toward the light projecting element.   4. The photoelectric sensor according to claim 2, wherein the center of the photosensitive surface of the light receiving element is arranged to be shifted toward the light projecting element side from the optical axis of the light receiving lens.

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