JP2002228762A - 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, diffused light emitted from a light projecting element 11 is changed into light with a plurality of parallel optical axes while traveling one round between a sensor body 10 and a multiple-string prism 20, and received by each light receiving element 12. That is, the frequency of round trips of the light is less in comparison with a conventional one, and the light does not pass through a half mirror, so that the decay of light is little. The sufficient light receiving quantity to the light receiving element is thereby secured to permit detection at the high S/N ratio. Furthermore, because of the constitution of providing one light projecting element 11 for a plurality of light receiving elements 12, the number of elements is cut down to attain cost reduction in comparison with the conventional constitution provided with the light projecting elements in the same number as the light receiving 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.
6 is shown in FIG. 6, in which a rotating mirror 3 is arranged near the focal point of a parabolic mirror 2 arranged opposite to a reflector 1 and provided at a position close to the 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]

Means for Solving the Problems <Invention of claim 1> A multi-optical axis photoelectric sensor according to the invention of claim 1 has a reflector disposed opposite to a sensor main body having a light projecting element and a light receiving element. Forms multiple optical axes between the sensor body and the reflector by reflecting the light received from the light emitting element toward the light receiving element, and detects the light blocking state of the optical axis based on the amount of light received by the light receiving element In a multi-optical axis photoelectric sensor, a plurality of light receiving elements are provided for one of the light emitting elements, and the light emitting elements are configured to project diffused light, while the plurality of light receiving elements are arranged in a line. The reflectors are arranged side by side,
A plurality of light-receiving elements are formed along the direction in which the light-receiving elements are gradually changed, and are provided with a plurality of reflecting portions for reflecting divergent light received from the light-emitting elements toward each of the light-receiving elements. It has features.

<Invention of Claim 2> In the multi-optical axis photoelectric sensor according to the invention of claim 2, a reflector is disposed opposite to a sensor body having a light projecting element and a light receiving element, and the reflector receives the light from the light projecting element. A multi-optical axis photoelectric sensor that forms a plurality of optical axes between the sensor body and the reflector by reflecting the reflected light toward the light receiving element, and detects the light blocking state of the optical axis based on the amount of light received by the light receiving element In the above, a plurality of light emitting elements are provided for one of the light receiving elements, and the plurality of light emitting elements are arranged in a line, and the reflector is gradually oriented along the direction in which the plurality of light emitting elements are arranged. Is formed by changing
It is characterized in that a plurality of reflecting portions for reflecting light received from each light emitting element toward one light receiving element are provided.

[0010]

According to the first aspect of the present invention, the light projected from one light projecting element spreads and irradiates the entire reflector, and the reflection angle is changed by each reflector provided on the reflector. Becomes light having a plurality of parallel optical axes,
To each 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.

According to the second aspect of the present invention, the plurality of optical axes are formed between the sensor body and the reflector by the light projected from the plurality of light projecting elements to the reflector, and the light of the reflector is formed. The light reflected by the reflector is collected,
The light is received by one light receiving element. Then, when the detection object is located in a region between the sensor body and the reflector, when the light is blocked, the amount of light received by the light receiving element decreases, whereby the detection object is detected.

[0012]

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 invention of claim 1, a plurality of light receiving elements are provided for one of the light emitting elements, and in the invention of claim 2, the plurality of light emitting elements are provided for one of the light receiving elements. is there. 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.

[0013]

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 multiple prism 20 as a reflector are provided facing each other. The sensor 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 body 10 facing the multiple prism 20. Each of these light emitting and receiving elements includes, for example, one light emitting element 11 arranged at the center of a row, and a plurality (for example, three in this embodiment) of light receiving elements 12 arranged on both upper and lower sides thereof. Wirings 11 and 12 are connected to a signal processing circuit (not shown). Also,
The light projecting element 11 is configured by, for example, an LED that projects 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 multiple prism 20 is provided with each light receiving element 1.
2 are provided. Each prism 21 includes first and second reflecting surfaces 22 and 23 approaching each other as going away from the sensor main body 10 in a direction in which the light emitting and receiving elements 11 and 12 are arranged. More specifically, a group of prisms 21 above the central part P1 facing the light projecting element 11 and a group of prisms 21 below the multi-prism 20 are symmetrical with each other.
In FIG. 1, the angle of the first reflection surface 22 on the side close to the center P1 is different for each prism 21. That is, as the prism 21 is farther away from the center P1, the first
Is raised on the vertical posture side. Specifically, as shown in FIG. 2, the first reflection surface 22 of the prism 21 closest to the central portion P1 is set at an inclination of 45 degrees with respect to the vertical direction, and the prism 21 further away therefrom In the example, the inclination is set to 45 degrees + a predetermined angle α with respect to the vertical direction. Here, the predetermined angle α corresponds to an angle α ′ of the optical axis with respect to a horizontal line, assuming an optical axis from the light projecting element 11 to each first reflection surface 22. That is,
As the prism 21 is farther away from the center P1, the light projecting element 11
Since the inclination of the optical axis toward each of the first reflecting surfaces 22 increases from that of the first reflecting surface 22, the first reflecting surface 22 is also set to have an inclination that is raised toward the side closer to the vertical posture.

On the other hand, the second reflecting surface 23 is set at an inclination of 45 degrees with respect to the vertical direction in all the prisms 21. Therefore, the light reflected in the vertical direction from each first reflection surface 22 is directed in the horizontal direction on the second reflection surface 23.

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 the light emitting element 11,
Each of the prisms 21 of the multiple prism 20 is irradiated. Here, as shown in FIG. 1, the light projected from the light projecting element 11 is irradiated at an angle inclined to the vertical side as the position is further away from the center part P1 of the multiple prism 20. Part P1
Since the first reflection surface 22 is raised toward the vertical position as the position is farther from the light, the light received from the light emitting element 11 is directed to the vertical direction on any of the first reflection surfaces 22. Reflected. The light directed in the vertical direction is directed horizontally in the second reflecting surface 23 of each prism 21 and returned to the sensor body 10 side. Thereby, a plurality of parallel optical axes are formed between the sensor main body 10 and the multiple prism 20. When a detection object is located between the sensor main body 10 and the multiple prism 20 in the multi-optical axis photoelectric sensor, light is blocked and the amount of light received by the light receiving element 12 is reduced. Is detected.

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 multiple prism 20.
The number of reciprocations is smaller than that of the conventional one, and the light does not pass through the 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 includes a plurality of light receiving elements 12
Is provided with one light emitting element 11 for
The cost can be reduced by reducing the number of elements as compared with the conventional one having the same number of light emitting elements as the light receiving elements.

<Second Embodiment> This embodiment is shown in FIG. 3 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 provided in one row include one light receiving element 12 arranged in the center of the row and a plurality of light emitting elements 12 arranged on both upper and lower sides thereof. 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,
The light is opposite to that of the first embodiment, and the light from the plurality of light projecting elements 11 is collected by the multiple prism 20 and received by one light receiving element 12. This allows
The same effects as in the first embodiment can be obtained.

In the configuration of the present embodiment, if the light emission timings of the plurality of light emission elements 11 are sequentially shifted and the light reception amount of the light reception element 12 is checked, which light emission element 11 Can be determined whether or not the light is blocked. This makes it possible to detect at which position the object is located.

If the plurality of light projecting elements 11 are turned on at the same cycle and at the same timing, the object to be detected can be detected instantaneously regardless of the position between the sensor body 10 and the multiple prism 20. It can be performed. <Other Embodiments> The present invention is not limited to the above-described embodiments. For example, embodiments described below are also included in the technical scope of the present invention. Various changes can be made without departing from the scope of the invention.

(1) In the first embodiment, a pair of reflecting surfaces 2 is provided for each of the plurality of light receiving elements 12.
Although two and 23 are provided, for example, as shown in FIG. 4, a configuration in which one reflecting surface 31 is provided on each of the mirror type reflectors 30 corresponding to the plurality of light receiving elements 12 is provided. Good. The diffused light received from one light emitting element 11 is changed by sequentially changing the angles of the reflecting surfaces 31 as the distance from the central portion P1 of the reflector 30 increases.
Light having a plurality of parallel optical axes can be returned to each light receiving element 12 of the sensor main body 10.

(2) In each of the first and second embodiments, the multiple prism 20 is used as a reflector. However, the present invention is not limited to this, and a mirror-type reflector may be used. In this case, each prism 21
The first and second reflecting surfaces 22 and 23 are formed while the
May be configured as, for example, a mirror type on which a metal film is deposited.
At this time, regarding the second reflecting surface 23, the light projecting element 11
It is desirable that the light directly incident from the light source be perpendicularly incident on the second reflection surface 23. By doing so, light that directly enters the second reflection surface from the light projecting element 11 can be returned to the light projecting element 11 so as not to enter another light receiving element 12. When a prism is used as a reflector as in each of the above embodiments, light directly incident on the second reflecting surface 23 from the light projecting element 11 passes through the reflecting surface 23 due to the incident angle and is reflected. Therefore, the light does not enter another light receiving element 12.

(3) Multiple prism 2 of the first embodiment
0, and as shown in FIG. 5, the light receiving surface of the mirror type reflector 40 is curved in a concave mirror shape as a whole,
The light emitting element 11 or the light receiving element 12 may be arranged at the focal position. This is because a plurality of reflectors for reflecting the divergent light received from the light projecting element 11 toward each light receiving element 12 can be configured.

(4) The sensor body 10 of the first embodiment
In the above, the light projecting element 11 is arranged at the center of the light receiving element row, but may be unevenly distributed.

[Brief description of the drawings]

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

FIG. 2 is an enlarged side sectional view of a part of a reflector provided in the multi-optical axis photoelectric sensor.

FIG. 3 is a side sectional view of a multi-optical axis photoelectric sensor according to a second embodiment.

FIG. 4 is a side view of a multi-optical axis photoelectric sensor according to a first modification;

FIG. 5 is a side view of a multi-optical axis photoelectric sensor according to a second modification;

FIG. 6 is a side view of a conventional multi-optical axis photoelectric sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Sensor main body 11 ... Light emitting element 12 ... Light receiving element 20, 30 ... Multiple prism 40 ... Mirror type reflector 21 ... Prism 22 ... 1st reflection surface 23 ... 2nd reflection surface 31 ... 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 light receiving elements are provided, and the light emitting element is configured to emit diffused light, while the plurality of light receiving elements are arranged in a line, and the reflector is provided with the plurality of light receiving elements A plurality of reflectors are formed along the direction, gradually changing the direction, and are provided to reflect divergent light received from the light emitting element toward each of the light receiving elements. Multi-optical axis photoelectric sensor. 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; Along with providing the light projecting element, the plurality of light projecting elements are arranged in a line, and the reflector is formed by gradually changing the direction along a direction in which the plurality of light projecting elements are arranged, A multi-optical axis photoelectric sensor, comprising: a plurality of reflectors for reflecting light received from each of the light projecting elements toward the one light receiving element.