JP2002228763A - Multi-optical-axis photoelectric sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-optical-axis photoelectric sensor capable of detecting at a high S/N ratio and reducing cost by cutting down the number of elements. SOLUTION: In this multi-optical-axis photoelectric sensor, light projected to a reflector 20 from a plurality of light projecting elements 11 provided at a sensor body 10 enters one end of each reflector constituent body 21 arranged with level difference. The light is offset by a prescribed quantity, returned to the sensor body 10 side from the other end of the reflector constituent body 21 and received by one light receiving element 12. When the light is shielded by a detection object, the light receiving quantity of the light receiving element 12 is reduced, and the detection object is thereby detected. Sine the light emitted from the light projecting element thus makes only one round trip between the sensor body 10 and the reflector 20, the number of round trips is small, and the decay of light is little compared with a conventional one. Cost can be reduced by cutting down the number of elements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflector reflection type multi-optical axis photoelectric sensor.

[0002]

2. Description of the Related Art A first conventional example of a multi-optical axis photoelectric sensor disclosed in Japanese Utility Model Laid-Open Publication No. 63-27798 is disclosed in Japanese Patent Application Laid-Open No. 63-27798. A plurality of pairs of elements are arranged, and the same number of optical axes as the pairs of light emitting and receiving elements are formed between the sensor body and the reflector. Then, when the detected object is located between the sensor main body and the reflector and blocks light, the amount of light received by the light receiving element is reduced, whereby the detected object is detected.

As a second conventional example, Japanese Patent Application Laid-Open No.
Japanese Patent No. 60545 has a pair of reflectors arranged opposite to each other, and one light emitting element and one light receiving element are arranged at both ends of one reflector. The light from the light projecting element is reflected back and forth a plurality of times between the two reflectors and then received by the light receiving element, so that a plurality of optical axes are formed between the two reflectors.

Further, as a third conventional example, Japanese Patent Publication No.
FIG. 8 shows an example disclosed in U.S. Pat. No. 6,1591, in which a rotating mirror 3 is arranged near a focal point of a parabolic mirror 2 arranged opposite to a reflector 1 and provided near a parabolic mirror 2. Light (for example, laser light) is projected from the light projecting element 4 toward the rotating mirror 3. Then, the rotation of the rotating mirror 3 causes the light to be distributed and radiated to the entire parabolic mirror 2, becomes parallel light, and travels toward the reflector 1, thereby forming a plurality of optical axes. The light returning in the reverse order is changed in direction by a half mirror 5 provided in front of the light projecting element 4 and received by the light receiving element 6.

[0005]

However, in the above-mentioned first conventional example, a plurality of pairs of a light projecting element and a light receiving element are required in correspondence with the number of optical axes. It cannot meet the demand for cost reduction by reducing the cost. On the other hand, in the second conventional example, the cost can be reduced by reducing the number of elements. However, when a wide detection area is secured, the number of round trips of light between the two reflectors increases, and the number of round trips increases accordingly. As a result, the light is attenuated and a sufficient amount of received light cannot be obtained, so that the S / N ratio is lowered and stable detection cannot be performed.

In the third conventional example, the cost can be reduced by reducing the number of elements, but the parabolic mirror 2 and the rotating mirror 3 are required, which leads to an increase in cost more than the reduction in the number of elements. . Furthermore, the rotating mirror 3
, There is a problem that the scanning speed is low and the detection speed is low.
In addition, since it receives reflected light via a half mirror,
Again, the amount of received light is attenuated, the S / N ratio is reduced, and stable detection cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a multi-optical axis photoelectric sensor capable of reducing the number of elements to reduce costs and performing detection at a high S / N ratio. With the goal.

[0008]

According to a first aspect of the present invention, there is provided a multi-optical axis photoelectric sensor.
A reflector is arranged opposite to a sensor body having a light emitting element and a light receiving element, and the reflector reflects light received from the light emitting element toward the light receiving element, so that a plurality of light beams are generated between the sensor body and the reflector. In a multi-optical axis photoelectric sensor that forms an axis and detects a light blocking state of an optical axis based on the amount of light received by a light receiving element, a plurality of light receiving elements are provided for one of the light projecting elements, and the plurality of light receiving elements are arranged in a line. A light-emitting element is arranged on an extension line arranged in a row, and the reflector is configured by arranging a plurality of reflector structures corresponding to a plurality of light-receiving elements in a direction orthogonal to the element arrangement direction in which the light-emitting and light-receiving elements are arranged. The body has a length corresponding to the distance from each corresponding light receiving element to the light emitting element, extends in the element arrangement direction, and has, at both ends thereof, a pair of reflecting surfaces whose directions are different from each other by 90 degrees, In addition, no reflective surface One of them has a wavy structure in which a plurality of small reflecting surfaces whose directions are different from each other by 90 degrees are alternately connected in series, and one reflecting surface of each reflector structure is arranged side by side, and the diffused light emitted from the light emitting element is formed. It is characterized in that light is applied to one of the reflecting surfaces of all the reflector structures, and travels from the other reflecting surface to each light receiving element.

In the multi-optical axis photoelectric sensor according to a second aspect of the present invention, a reflector is disposed to face a sensor body having a light emitting element and a light receiving element, and the light received by the reflector from the light emitting element is directed to the light receiving element. One of the light receiving elements in a multi-optical axis photoelectric sensor that forms a plurality of optical axes between the sensor body and the reflector by reflecting the light, and detects a light blocking state of the optical axis based on the amount of light received by the light receiving elements. A plurality of light emitting elements are provided, and a plurality of light emitting elements are arranged in a line. A light receiving element is arranged on an extension line, and the reflector emits and receives a plurality of reflector structures corresponding to the plurality of light emitting elements. The elements are arranged side by side in a direction orthogonal to the element arrangement direction in which the elements are arranged, and each reflector structure has a length corresponding to the distance from each corresponding light emitting element to the light receiving element, and extends in the element arrangement direction, and At both ends, the orientation of each other Comprising a 0 ° from the pair of reflecting surfaces,
Further, any one of the reflection surfaces has a wave structure in which a plurality of small reflection surfaces having directions different from each other by 90 degrees are alternately arranged in a row, and one reflection surface of each reflector structure is arranged side by side. Then, the light emitted from each light emitting element is irradiated on the other reflecting surface arranged in a step, and the light is directed from the other reflecting surface of each reflector structure to the light receiving element. It has features.

[0010]

According to the first and second aspects of the present invention, the other reflecting surface (reference numeral 23 in FIG. 2) provided on each reflector structure is provided.
2) and a pair of adjacent small reflecting surfaces (reference numeral 2 in FIG. 2).
As shown in FIG. 3, the three directions are different from each other by 90 degrees (see reference numerals 23, 24, and 24 in FIG. 3). And converts the received light into light parallel to the light. The amount of offset between the received light and the returned light is an amount corresponding to the length of each reflector structure. In the present invention, the length corresponds to the distance between the light emitting element and the light receiving element. Let me do it.

According to the first aspect of the present invention, the light projected from one light projecting element provided in the sensor main body spreads and enters one end of each reflector structure, and is offset by a predetermined amount, so that each of the reflector structures is offset. It is returned to the sensor body from the other end of the reflector structure. At this time, the light is divided into light having a plurality of optical axes, and each light is received by the light receiving element, depending on the difference in the length of each reflector constituent body. And since the detection object is located between the sensor main body and the reflector, when the light is blocked, the amount of light received by the light receiving element is reduced, whereby the detection object is detected.

According to the second aspect of the present invention, the light projected from the plurality of light projecting elements provided on the sensor main body to the reflector is incident on one end of each of the reflector constituents arranged stepwise, and has a predetermined amount. And the light is returned to the sensor body from the other end of the reflector structure, and is received by one light receiving element. And since the detection object is located between the sensor main body and the reflector, when the light is blocked, the amount of light received by the light receiving element is reduced, whereby the detection object is detected.

[0013]

As described above, according to the multi-optical axis photoelectric sensor of the first and second aspects, the light emitted from the light projecting element is
Since only one reciprocation is made between the sensor main body and the reflector, the number of reciprocations is smaller than that of the conventional one, and there is no interposition of a half mirror unlike the conventional one, so that light attenuation is small. Therefore, a sufficient amount of light received by the light receiving element is secured, and detection with a high S / N ratio can be performed. Moreover, in the first aspect of the present invention, a plurality of light receiving elements are provided for one of the light emitting elements.
A plurality of light emitting elements are provided for each. That is, according to the present invention, one of the light emitting and receiving elements can be made smaller than the number of optical axes, and the number of light emitting and receiving elements is reduced by the number of elements as compared with the conventional one in which both of the light emitting and receiving elements are provided by the same number as the optical axes Cost can be reduced.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> An embodiment of the present invention will be described below with reference to FIGS. The multi-optical axis photoelectric sensor according to the present embodiment includes a sensor body 10 provided separately.
And a reflector 20 are provided so as to face each other. The sensor main body 10 has a columnar shape extending in the vertical direction in FIG. 1, and a plurality of light emitting and receiving elements are arranged in a line on a surface of the sensor main body 10 facing the reflector 20. These light emitting and receiving elements include, for example, one light receiving element 12 arranged at the upper end of a row, and a plurality (for example, three in this embodiment) of light emitting elements 11 arranged below the light receiving element 12. Wirings connected to the elements 11 and 12 are connected to a signal processing circuit (not shown). The light emitting element 11 is
For example, it is configured by an LED that emits diffused light. On the other hand, the light receiving element 12 outputs a light receiving signal of a level corresponding to the amount of received light to the signal processing unit. Further, the signal processing unit outputs a detection signal when the light receiving signal falls below a predetermined reference value set in advance.

Now, the reflector 20 is provided for each of the light projecting elements 11.
(In this embodiment, three) in a horizontal direction (a direction orthogonal to the element arrangement direction in which the light emitting and receiving elements 11 and 12 are arranged).

Here, FIG. 2 shows one reflector component 21 separately from the other reflector components 21. As shown in FIG.
At each end of the prism, a pair of reflecting surfaces 22 and 23 whose directions are different from each other by 90 degrees are formed, and among them, the first reflecting surface 22 shown on the upper side in FIG. It has a wavy structure in which small reflecting surfaces 24 are connected. Also,
The directions of the adjacent small reflection surfaces 24 are different from each other by 90 degrees.

Accordingly, the second reflecting surface 23 shown on the lower side in FIG. 2 and a pair of small reflecting surfaces 24 adjacent to the first reflecting surface 22 are schematically shown in FIG. As shown, three orthogonal planes having directions mutually different by 90 degrees are formed.
Here, as shown in comparison with FIG. 3A and FIG. 3B, the light projected toward the three orthogonal planes is one on each of the planes 23, 24, and 24 constituting the three orthogonal planes. When reflected and returned each time, the optical axis J1 of the projected light (see FIG. 3) and the optical axis J2 of the returned light (see FIG. 3) always have a parallel relationship.

This will be described with reference to the reflector structure 21. As shown in FIG. 4, the light of the optical axis J1 which is oblique to the vertical direction and travels toward the second reflection surface 23 of the reflector structure 21 is shown in FIG. The light is reflected by the second reflecting surface 23 and the pair of small reflecting surfaces 24, 24, and is returned as light of the optical axis J2 parallel to the optical axis J1 offset by a predetermined amount. . Alternatively, as shown in FIG. 5, the second
Similarly, the light of the optical axis J1 toward the reflection surface 23 returns as the light of the optical axis J2 parallel to the optical axis J1 offset by a predetermined amount.

Here, the offset amount between the two optical axes J1 and J2 corresponds to the length of each reflector structure 21, and in the present embodiment, the length of each reflector structure 21 corresponds to the corresponding length. It is set based on the distance from the light projecting element 11 to the light receiving element 12. Then, the reflector 20 is configured by arranging the reflector components 21 side by side in the order of length from the right side in FIG.

The reflector 20 is used by being housed in a case 50 as shown in FIG.
Has a structure in which an intermediate portion in the longitudinal direction of each reflector component 21 is covered, and a window 51 is formed in a portion facing a position near an end of the reflector component 21. This prevents light from the light emitting element 11 from being reflected on the outer surface of the reflector 20.

Next, the operation and effect of the multi-optical axis photoelectric sensor of this embodiment will be described. When the start switch of the multi-optical axis photoelectric sensor is turned on, diffused light is emitted from each light emitting element 11 and enters the lower end of each reflector structure 21 as shown in FIG. Then, the second of each reflector structure 21
1 is reflected upward in FIG. 1 by the first reflecting surface 22 at a position offset by a predetermined amount, and reflected by a pair of adjacent small reflecting surfaces 24, 24 so that each of the reflector structures 21 Light is emitted from the upper end of the.

Here, the optical axis J1 of the light entering each reflector component 21 and the optical axis J2 of the emitted light are offset in parallel by an amount corresponding to the length of the reflector component 21 and are parallel. become. Thereby, each reflector structure 2
1 receives light from the corresponding light emitting element 11 at the lower end,
Assuming that the sensor body 10 and each of the reflector components 21 are
Even if it is shifted, it always goes to the light receiving element 12 from the upper end of each reflector structure 21. Thereby, a plurality of parallel optical axes connecting the light emitting and receiving elements are formed between the sensor body 10 and the reflector 20. The sensor body 10 and the reflector 20 of the multi-optical axis photoelectric sensor
When the detected object is located between the positions, the light is blocked, and the amount of light received by the light receiving element 12 is reduced. Thus, the detected object is detected.

The light received by one end of each reflector 20 from the uncorresponding light projecting element 11 and emitted from the other end is reflected in a direction different from that of the light receiving element 12.

As described above, according to the multi-optical axis photoelectric sensor of the present embodiment, the light emitted from the light projecting element 11 travels only one round trip between the sensor body 10 and the reflector 20. The number of reciprocations is smaller than that of the prior art, and the light does not pass through a half mirror unlike the conventional one, so that light attenuation is small. Therefore, a sufficient amount of light received by the light receiving element 12 is secured, and detection with a high S / N ratio can be performed. Moreover, the multi-optical axis photoelectric sensor of the present embodiment has a configuration in which one light projecting element 11 is provided for a plurality of light receiving elements 12, so that the conventional one having the same number of light projecting elements as the light receiving elements. Rather, the cost can be reduced by reducing the number of elements.

<Second Embodiment> This embodiment is shown in FIG. 7 and has a configuration in which the light emitting element and the light receiving element of the first embodiment are interchanged. That is, the sensor body 10
The plurality of light emitting and receiving elements arranged in a row
It comprises one light emitting element 11 and a plurality of light receiving elements 12 arranged below the light emitting element 11. Other configurations are the same as those of the first embodiment, and thus the same configurations are denoted by the same reference numerals and overlapping description will be omitted.

According to the multi-optical axis photoelectric sensor of this embodiment,
With respect to the first embodiment, the light is turned in the opposite direction, and the light from the plurality of light projecting elements 11 is collected by the reflector 20 and received by the light receiving element 12. Thereby, the first
An effect similar to that of the embodiment is obtained.

It should be noted that the present invention is not limited to the above-described embodiment, and can be implemented with various modifications other than the first and second embodiments without departing from the scope of the invention.

[Brief description of the drawings]

FIG. 1 is a perspective view of a multi-optical axis photoelectric sensor according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing one reflector structure.

FIG. 3 is a perspective view showing three orthogonal surfaces.

FIG. 4 is a side view of a reflector structure.

FIG. 5 is a perspective view of the reflector assembly viewed from obliquely above.

FIG. 6 is a side sectional view showing a cover;

FIG. 7 is a perspective view of a multi-optical axis photoelectric sensor according to a second embodiment.

FIG. 8 is a side view of a conventional multi-optical axis photoelectric sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Sensor main body 11 ... Light projection element 12 ... Light receiving element 20 ... Reflector 21 ... Reflector structure 22, 23 ... Reflection surface 24 ... Small reflection surface

Claims (2)

[Claims] 1. A sensor body having a light emitting element and a light receiving element, wherein a reflector is disposed to face the sensor body, and the reflector reflects light received from the light emitting element toward the light receiving element, whereby the sensor body is provided. And a plurality of optical axes formed between the reflector and the light-receiving element, a multi-optical axis photoelectric sensor for detecting a light-shielded state of the optical axis based on the amount of light received by the light-receiving element; A plurality of the light receiving elements are provided, and the light emitting element is arranged on an extension line in which the plurality of the light receiving elements are arranged in a line. The reflector includes a plurality of reflector structures corresponding to the plurality of the light receiving elements. The light-receiving elements are arranged side by side in a direction orthogonal to the element arrangement direction, and each of the reflector structures has a length corresponding to a distance from each of the corresponding light-receiving elements to the light-projecting element, and is arranged in the element arrangement direction. In And at both ends thereof, a pair of reflecting surfaces whose directions are different from each other by 90 degrees, and one of the reflecting surfaces is a plurality of small reflecting surfaces whose directions are different from each other by 90 degrees. It has a waveform structure, one reflective surface of each of the reflector components, side-by-side, diffused light emitted from the light emitting element is irradiated to one reflective surface of all the reflector components, A multi-optical axis photoelectric sensor, wherein the other reflection surface is directed toward each of the light receiving elements. 2. A sensor body having a light emitting element and a light receiving element, wherein a reflector is disposed to face the sensor body, and the reflector reflects the light received from the light emitting element toward the light receiving element, whereby the sensor body is provided. A plurality of optical axes formed between the light receiving element and the reflector, and detecting a light blocking state of the optical axis based on the amount of light received by the light receiving element; The light emitting element is provided, and the light receiving element is arranged on an extension line in which the plurality of light emitting elements are arranged in a line.The reflector includes a plurality of reflector structures corresponding to the plurality of light emitting elements. The light emitting and receiving elements are arranged side by side in a direction orthogonal to the element array direction, and each of the reflector structures has a length corresponding to a distance from each of the corresponding light emitting elements to the light receiving element, and the element array is formed. Extend in the direction And at both ends thereof, a pair of reflecting surfaces whose directions are different from each other by 90 degrees, and one of the reflecting surfaces is a plurality of small reflecting surfaces whose directions are different from each other by 90 degrees. It has a waveform structure, while irradiating the light emitted from each light-emitting element to the other reflecting surface arranged stepwise, while arranging one reflecting surface of each reflector structure side by side Wherein the light is directed from the other reflection surface of each of the reflector structures to the light receiving element.