JP6598556B2 - Photoelectric sensor - Google Patents

Description

  The present invention relates to a photoelectric sensor that detects a transparent body and whose light projecting axis and light receiving axis are not coaxial.

2. Description of the Related Art Conventionally, a reflector reflection type photoelectric sensor that detects a transparent body having high transmittance is known (see, for example, Patent Document 1). In this transparent body detection photoelectric sensor, for example, as shown in FIG. 5, a light projecting axis of a light projecting unit 1016 having a light projecting element 1012 and a light projecting lens 1013, and a light receiving unit having a light receiving lens 1014 and a light receiving element 1015. There is a photoelectric sensor 101 whose light receiving axis 1017 is not coaxial. In this photoelectric sensor 101, the light projecting element 1012 is arranged in accordance with the central axis of the light projecting lens 1013, so that the projected light can be blown straight and the detection distance can be increased. The light receiving element 1015 is also arranged in accordance with the central axis of the light receiving lens 1014. In FIG. 5, reference numeral 1011 denotes a circuit board.
(For example, refer to Patent Document 1).

JP 2009-152813 A

In such a transparent body detecting photoelectric sensor, as shown in FIG. 6, the light incident on the light receiving unit 1017 passes through the transparent body 5 to be detected and is reflected by the reflector (reflector) 2. The combined light 502 and the light 503 reflected from the surface of the transparent body 5 are combined. In FIG. 6, reference numeral 501 denotes light projected from the light projecting unit 1016, and reference numeral 504 denotes the transport direction of the transparent body 5.
Here, for example, as shown in FIG. 7, when the transparent body 5 is inclined and conveyed, the amount of light 503 b reflected on the surface of the transparent body 5 is larger than the light 502 reflected by the reflector 2. . Therefore, stable detection cannot be performed.

  Therefore, conventionally, for example, as shown in FIG. 8, the photoelectric sensor 101 and the reflector 2 are arranged so as to be inclined more than an angle at which the transparent body 5 is inclined. That is, when the maximum inclination angle of the transparent body 5 is α and the inclination angle of the photoelectric sensor 101 and the reflector 2 is β, the transparent body 5 is inclined so that β> α.

  Alternatively, in order not to be affected by the tilt of the transparent body 5, for example, as shown in FIG. 9, the plane including the light projecting unit 1016 and the light receiving unit 1017 of the photoelectric sensor 101 with respect to the plane in which the transparent body 5 tilts. The photoelectric sensor 101 is vertically installed so that is vertical.

  However, when the photoelectric sensor 101 is used for positioning the transparent body 5 (when the transparent body 5 is stopped at a predetermined position for operation), the photoelectric sensor 101 and the reflector 2 are tilted as shown in FIG. There is a problem that it cannot be arranged. That is, if the photoelectric sensor 101 and the reflector 2 are disposed obliquely, high positioning accuracy cannot be realized.

  Further, when the transparent body 5 is inclined only in the two-dimensional direction, this can be dealt with by changing the mounting direction of the photoelectric sensor 101 as shown in FIG. However, when a high-speed conveyor or the like is used, or when the transparent body 5 itself is light, the transparent body 5 may be inclined in a three-dimensional direction. As described above, when the transparent body 5 is tilted in the three-dimensional direction, there is a problem that the mounting direction of the photoelectric sensor 101 as shown in FIG.

  The present invention has been made to solve the above-described problems, and in a photoelectric sensor for detecting a transparent body in which a light projecting axis and a light receiving axis are not coaxial, the photoelectric sensor is transparent without being disposed obliquely. An object of the present invention is to provide a photoelectric sensor capable of avoiding malfunction due to body tilt.

The photoelectric sensor according to the present invention includes a light projecting element and a light projecting lens, and is disposed at a position different from the light projecting axis of the light projecting unit and the light projecting axis of the light projecting unit. In the photoelectric sensor for detecting the transparent body, the light projecting element has a light projecting distance opposite to the light projecting element with respect to the central axis of the light projecting lens. It is a distance that allows light to reach the disposed reflector , and is shifted to the light receiving portion side by a predesigned value so that it is difficult for reflected light from the transparent body to enter the light receiving portion.

  According to the present invention, since it is configured as described above, in the photoelectric sensor for detecting a transparent body in which the light projecting axis and the light receiving axis are not coaxial, malfunctioning due to the inclination of the transparent body without arranging the photoelectric sensor obliquely. Can be avoided.

It is a figure which shows the structural example of the photoelectric sensor which concerns on Embodiment 1 of this invention, (a) It is a figure which shows the state seen from the element arrangement direction, (b) The state seen from the direction perpendicular | vertical to an element arrangement direction FIG. It is a figure explaining the effect of the photoelectric sensor which concerns on Embodiment 1 of this invention, (a) It is a figure which shows the state seen from the element arrangement direction, (b) The state seen from the direction perpendicular | vertical to an element arrangement direction FIG. It is a figure explaining the effect of the photoelectric sensor which concerns on Embodiment 1 of this invention. It is a figure which shows another example of a structure of the photoelectric sensor which concerns on Embodiment 1 of this invention, (a) It is a figure which shows the state seen from the element arrangement direction, (b) It sees from the direction perpendicular | vertical to an element arrangement direction. FIG. It is a figure which shows the structural example of the conventional photoelectric sensor. It is a figure explaining the light which enters into a light-receiving part in the conventional photoelectric sensor. It is a figure which shows the case where a detection body is conveyed diagonally in the conventional photoelectric sensor. It is a figure which shows the case where the conventional photoelectric sensor and reflector are arrange | positioned diagonally. It is a figure which shows the case where the conventional photoelectric sensor is installed vertically.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a photoelectric sensor 1 according to Embodiment 1 of the present invention, (a) a view seen from the element arrangement direction, and (b) a direction perpendicular to the element arrangement direction. It is a figure which shows the state seen from.
The photoelectric sensor 1 shown in FIG. 1 detects a transparent body 5 such as a plastic bottle, and is a photoelectric sensor in which the light projecting axis of the light projecting unit 16 and the light receiving axis of the light receiving unit 17 are not coaxial. The detection principle and basic configuration of the transparent body 5 by the photoelectric sensor 1 are the same as the conventional configuration, and only the configuration related to the present invention will be described below. In FIG. 1, illustration of the housing of the photoelectric sensor 1 is omitted.

A light projecting element 12 and a light receiving element 15 are connected to a printed circuit board 11 on which various circuits of the photoelectric sensor 1 are mounted. In addition, the photoelectric sensor 1 is provided with a light projecting lens 13 disposed to face the light projecting element 12 and a light receiving lens 14 disposed to face the light receiving element 15. Here, the light projecting element 12 and the light projecting lens 13 constitute a light projecting part 16, and the light receiving lens 14 and the light receiving element 15 constitute a light receiving part 17.
As shown in FIG. 2, a reflector (reflecting plate) 2 that recursively reflects light projected from the photoelectric sensor 1 is provided on the opposite side of the photoelectric sensor 1 across the detection region. For example, a corner cube reflector is used as the reflector 2.

The light projecting element 12 emits light. For example, an LED is used as the light projecting element 12. An example of the arrangement of the light projecting elements 12 will be described later.
The light projecting lens 13 condenses the light emitted by the light projecting unit 16. The light projecting lens 13 does not have an inclination angle with respect to the light projecting element 12. The light condensed by the light projecting lens 13 is projected onto the detection area. The projected light passes through the transparent body 5 to be detected existing on the detection area, is reflected by the reflector 2, and is reflected by the surface of the transparent body 5.

The light receiving lens 14 collects the light projected and reflected by the light projecting unit 16.
The light receiving element 15 converts the light collected by the light receiving lens 14 into an electric signal (current). For example, a photodiode is used as the light receiving element 15. In the photoelectric sensor 1, the transparent body 5 is detected using the electrical signal converted by the light receiving element 15.

Next, the arrangement of the light projecting element 12 will be described.
In the present invention, as shown in FIG. 1A, the light projecting element 12 is arranged with respect to the central axis of the light projecting lens 13. In the arrangement direction (hereinafter referred to as element arrangement direction), the light-receiving element 15 is displaced (shift amount l ₁ ). Thereby, for example, as shown in FIG. 2A, the light 201 projected from the light projecting unit 16 can be directed outward (right side) with respect to the light projecting axis. As a result, even when the transparent body 5 is inclined in the two-dimensional direction, the light 203 reflected by the surface of the transparent body 5 can be made difficult to enter the light receiving unit 17. In FIG. 2, reference numeral 202 indicates the light reflected by the reflector 2, and reference numeral 204 indicates the transport direction of the transparent body 5.

Further, in FIG. 1B, the light projecting element 12 is shifted from the central axis of the light projecting lens 13 in a direction perpendicular to the element arrangement direction (shift amount l ₂ ). As a result, for example, as shown in FIG. 2B, the light 201 projected from the light projecting unit 16 can be directed outward (upward) with respect to the light projection axis. As a result, even when the transparent body 5 is inclined in the three-dimensional direction, the light 203 reflected by the surface of the transparent body 5 can be made difficult to enter the light receiving unit 17.

Note that as the shift amounts l ₁ and l _{2 of the} light projecting element 12 increase, the light projected from the light projecting unit 16 can be directed to the outside of the light projecting axis, and the light reflected from the surface of the transparent body 5. Becomes difficult to enter the light receiving unit 17. However, when the shift amounts l ₁ and l _{2 of the} light projecting element 12 are increased, the light projecting distance is shortened. For this reason, the shift amounts l ₁ and l ₂ of the light projecting element 12 are set to values that can fly the light projected from the light projecting unit 16 to the necessary light projecting distance according to the use of the photoelectric sensor 1. Pre-designed. For example, in a normal transparent body detection application, when the diameter of the projection lens 13 is about φ6 to 6.5 and the distance between the projection element 12 and the projection lens 13 is about 10 mm, the projection is performed. The element 12 is shifted about 200 μm from the central axis of the light projecting lens 13.

  In this way, by shifting the light projecting element 12 from the central axis of the light projecting lens 13, it is not necessary to dispose the photoelectric sensor 1 and the reflector 2 obliquely as in the prior art. Therefore, for example, as shown in FIG. 3, the photoelectric sensor 1 can be used for positioning the transparent body 5. That is, the photoelectric sensor 1 and the reflector 2 can be arranged straight in a direction perpendicular to the conveying direction 204 of the conveyor, and high positioning accuracy with respect to the transparent body 5 can be realized. In FIG. 3, reference numeral 301 indicates a position where the transparent body 5 is positioned.

  Further, by shifting the light projecting element 12 from the central axis of the light projecting lens 13 in the element arrangement direction and in a direction perpendicular to the element arrangement direction, there is no restriction on the mounting direction of the photoelectric sensor 1 and vertical and horizontal placement is free. Can be decided. In addition, when the transparent body 5 is conveyed by a high-speed conveyor or the like, or when the transparent body 5 itself is light, the transparent body 5 is reflected on the surface of the transparent body 5 even when it is inclined in the three-dimensional direction. It becomes difficult for light to enter the light receiving unit 17.

  In the above description, the case where the light projecting element 12 is surface-mounted on the printed board 11 has been described. However, as shown in FIG. 4, the present invention is similarly applied to the case where the light projecting element 12 is a dip component. Is applicable.

  In the above description, the case where the light projecting element 12 is shifted from the central axis of the light projecting lens 13 in the element array direction and the direction perpendicular to the element array direction is shown. It may be shifted only in the element arrangement direction. Thereby, it is possible to cope with the case where the transparent body 5 is displaced only in the two-dimensional direction.

  As described above, according to the first embodiment, the light projecting unit 16 that projects the light and the light projecting axis of the light projecting unit 16 are different from each other. In the photoelectric sensor 1 for detecting the transparent body 5, the light projecting element 12 is arranged at the center of the light projecting lens 13. The light receiving unit 17 receives the light projected and reflected by the light projecting unit 16. Since the light-projecting axis and the light-receiving axis are not coaxial, the photoelectric sensor 1 for detecting a transparent body in which the light-projecting axis and the light-receiving axis are not coaxial with each other, the photoelectric sensor 1 and the reflector 2 are obliquely arranged with a simple configuration. Therefore, it is possible to avoid malfunction due to the inclination of the transparent body 5.

  Further, by shifting the light projecting element 12 from the central axis of the light projecting lens 13, not only the detection of the transparent body 5 is stabilized, but also the malfunction resistance to the mirror body (light shielding body) can be enhanced. That is, in an actual line, when a mirror body such as SUS is arranged on the line, when a mirror body is attached to a part of the transparent body 5, the mirror body is transported together with the transparent body 5. There are cases. Even in such a case, by shifting the light projecting element 12 from the central axis of the light projecting lens 13, it is possible to make it difficult for light from the mirror body to enter the light receiving unit 17, and to avoid malfunction. .

  Moreover, since the light projection lens 13 can be configured without using a special lens, the light projection lens 13 can be used in common with a lens for other purposes (for example, a long distance detection purpose). As a result, cost can be suppressed.

  In the present invention, any constituent element of the embodiment can be modified or any constituent element of the embodiment can be omitted within the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Photoelectric sensor 2 Reflector 5 Transparent body 11 Printed circuit board 12 Light projection element 13 Light projection lens 14 Light reception lens 15 Light reception element 16 Light projection part 17 Light reception part

Claims (2)

Light that has a light projecting element and a light projecting lens, is disposed at a position different from the light projecting axis of the light projecting unit, and is projected and reflected by the light projecting unit. A photoelectric sensor that detects a transparent body,
It said light emitting element, said the center axis of the projection lens, the reflection of the distance of projection distance light can reach reflector disposed opposite to the light projecting element and from the transparent body to the light receiving portion A photoelectric sensor, wherein the photoelectric sensor is arranged so as to be shifted toward the light receiving portion by a value designed in advance so that light does not easily enter. The photoelectric sensor according to claim 1, wherein the light projecting element is arranged so as to be shifted in a direction perpendicular to an arrangement direction of the light projecting unit and the light receiving unit with respect to a central axis of the light projecting lens.

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