JP2008058291A - Photoelectric sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric sensor capable of executing a detection operation and a diagnostic operation for an object at the same time. <P>SOLUTION: An operation switch includes a plurality of sets of light projection elements 11a, 11b and light receiving elements 12a, 12b, and one-portions of projection lights from the respective sets of light projection elements 11a, 11b are photoreceived by the other sets of light receiving elements 12a, 12b by an optical waveguide. A CPU 21 of the operation switch light-projection-drives sequentially the respective sets of light projection elements 11a, 11b, and detects an object to be detected, based on a detection signal X1 output from a detecting comparator 24, in response to light receiving quantities of the light receiving elements 12a, 12b arranged opposedly to the light-projection-driven light projection elements 11a, 11b, in light projection timings in the respective sets. The CPU 21 further judges a failure, based on a determination signal X2 output from a failure determining comparator 25, in response to light receiving quantities of the other sets of light receiving elements 12a, 12b for receiving the one-portions of the projection lights from the respective sets of light-projection-driven light projection elements 11a, 11b, in the light projection timings in the respective sets. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a photoelectric sensor that detects the presence / absence of an object by the amount of incident light.

  Conventionally, a photoelectric sensor is used to detect the presence or absence of an object. The photoelectric sensor includes a light projecting element and a light receiving element that are arranged to face each other, and outputs a signal corresponding to a change in the amount of light received by the light receiving element. The presence / absence of an object can be detected by comparing the level of this signal with the determination level.

By the way, if the light projecting element or the light receiving element fails or the light projecting element deteriorates, the detection of the object is hindered. For this reason, some photoelectric sensors detect a decrease in sensitivity by reducing the drive current supplied to the light projecting element (see, for example, Patent Document 1).
Japanese Utility Model Publication No. 57-102875

  However, since the photoelectric sensor reduces the drive current supplied to the light projecting element to reduce the amount of light irradiated toward the light receiving element, the object detection operation and the sensitivity decrease detection operation can be performed simultaneously. There is a problem that it is not possible.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a photoelectric sensor capable of simultaneously performing an object detection operation and a diagnosis operation.

  In order to achieve the above object, the invention described in claim 1 includes: a light projecting unit that irradiates light toward the detection region; and a light receiving unit that receives light from the detection region in a pair with the light projecting unit. In a photoelectric sensor that includes a plurality of sets and detects an object to be detected in the detection area, a part of the light from the light projecting means of each set is not passed through the detection area by a light receiving means different from the light projecting means. Based on the amount of light received by the light receiving means paired with the light projecting means to be projected and driven at the light projecting timing of each set. Based on the amount of light received by the detecting means for detecting the detected object and the light receiving means of the other set in which a part of the light of the light projecting means driven for light projection can be received at the light projecting timing of each set. Failure determination means for performing failure determination.

  According to this configuration, when the detection object is detected by one set of light projecting means and light receiving means, the light receiving means capable of receiving a part of the light from the light projecting means of the set fails. In order to perform the determination, it is possible to determine the failure while continuing the normal detection operation.

  According to a second aspect of the present invention, in the photoelectric sensor according to the first aspect, each set of the light projecting means and the light receiving means is arranged to face each other with the detection region interposed therebetween. According to this configuration, the light projecting element and the light receiving element form an optical axis that passes through the detection region, and the detected object is easily detected by blocking the detected object.

  According to a third aspect of the present invention, in the photoelectric sensor according to the second aspect, the light projecting means and the light receiving means are alternately arranged for each set. According to this configuration, since the light projecting unit and the light receiving unit in different sets are arranged adjacent to each other, it is easy to receive a part of the light from the light projecting unit as the monitor light.

  According to a fourth aspect of the present invention, in the photoelectric sensor according to any one of the first to third aspects, the light from the light projecting unit is disposed between the adjacent light projecting unit and the light receiving unit. Is provided with light guiding means for guiding a part of the light to the light receiving means. According to this configuration, a part of the light from the light projecting unit is received by the light guide unit.

  According to a fifth aspect of the present invention, in the photoelectric sensor according to any one of the first to third aspects, each set of the light projecting unit does not pass through the other region of the light receiving unit and the detection region. The light receiving means of each set is arranged to face the other light projecting means without passing through the detection area. According to this configuration, the light emitted from each set of light projecting means is directly incident on another set of light receiving means without being blocked by the detected object in the detection region, so that the detection operation is performed simultaneously. Failure determination is possible.

  According to a sixth aspect of the present invention, in the photoelectric sensor according to any one of the first to fifth aspects, the output signal level of the light receiving means is compared with a comparison determination level, and the comparison result is determined. A comparator for detection that outputs a detection signal, a comparator for failure determination that compares an output signal level of the light receiving means and a failure determination level, and outputs a determination signal according to the comparison result, and each of the sets of light receiving means Opening / closing means connected to each of the detection comparator and the failure determination comparator, and each set of light receiving means are sequentially connected to the detection comparator, and arranged opposite to the light receiving means connected to the detection comparator. The control means for controlling the opening / closing means to connect another set of light receiving means capable of receiving a part of the light from the projected light projecting means to the failure determination comparator. Those having a means.

  According to this configuration, since each set of light receiving means is sequentially connected to the detection comparator and the failure determination comparator, it is not necessary to provide a detection comparator and a failure determination comparator for each set, and the scale of the entire photoelectric sensor Can be suppressed.

  As described above, according to the present invention, it is possible to provide a photoelectric sensor capable of simultaneously performing an object detection operation and a diagnosis operation.

Hereinafter, an embodiment in which the photoelectric sensor of the present invention is embodied as an operation switch will be described with reference to FIGS.
As shown in FIG. 1, the operation switch 1 is provided on the operation table S of the processing apparatus. The operation switch 1 is operated by an operator to start and stop the machining apparatus.

  The operation switch 1 includes a hollow case 2 that opens to the lower side, and the opening of the case 2 is closed by a plate-like base 3 constituted by screws (not shown). The case 2 is made of a light-transmitting material, and has a base portion 4 that is open in the lower side and formed in a substantially square box shape in plan view, and a protrusion that is formed in a substantially rectangular parallelepiped box shape that extends upward from the base portion 4. And a setting part 5.

  A first substrate 6 is fixed in the base portion 4, and a second substrate 7 is fixed in the protruding portion 5 so as to be orthogonal to the first substrate 6. As shown in FIG. 2, a plurality of pairs (two pairs in this embodiment) of light projecting elements 11a and 11b and light receiving elements 12a and 12b as light receiving means are disposed in the case 2. Yes. Two pairs of light projecting / receiving elements facing each other (the first light projecting element 11a and the first light receiving element 12a, the second light projecting element 11b and the second light receiving element 12b) are adjacent to each other, and the light projecting element and the light receiving element for each set. The elements are arranged alternately.

  More specifically, the first light emitting element 11a and the second light receiving element 12b are mounted on the first substrate 6, and the first light receiving element 12a and the second light projecting element 11b are mounted on the second substrate 7. Is arranged. Further, the first light projecting element 11 a and the second light receiving element 12 b mounted on the first substrate 6 are arranged along the side of the base portion 4, and the second light projecting element mounted on the second substrate 7. The optical element 11 b and the first light receiving element 12 a are disposed in the vicinity of the upper end of the protruding portion 5. And the projection light from the 1st light projection element 11a mounted on the 1st board | substrate 6 permeate | transmits the upper surface (outer surface 4a) of the base part 4, and is radiate | emitted on the outer side of the case 2, and the convex part 5 Is incident on the first light receiving element 12a disposed inside the case 2 (inside the projecting portion 5). Further, the light emitted from the second light projecting element 11b mounted on the second substrate 7 is transmitted through the outer surface 5a to be emitted to the outside of the case 2, and is transmitted through the outer surface 4a to pass through the inside of the case 2 ( The light is incident on the second light receiving element 12b disposed in the base portion 4).

  As shown in FIG. 1, the base portion 4 and the projecting portion 5 are formed such that the outer surface 4a and the outer surface 5a form a substantially right angle, more specifically, an angle equal to or greater than a right angle. . Then, optical axes L1 and L2 are formed between the light projecting elements 11a and 11b and the light receiving elements 12a and 12b facing the space formed between the outer side surfaces 4a and 5a. Specifically, a first optical axis L1 is formed in which the projection light from the light projecting element 11a on the first substrate 6 is received by the light receiving element 12a on the second substrate 7. Similarly, a second optical axis L2 is formed in which the projection light from the light projecting element 11b on the second substrate 7 is received by the light receiving element 12b on the first substrate 6.

  When the operator grips the convex portion 5 with his / her hand, the finger enters the space formed between the outer side surfaces 4a and 5a, and at least one of the first optical axis L1 and the second optical axis L2 Block. Then, since the projection light from the light projecting elements 11a and 11b is not received by the opposing light receiving elements 12a and 12b, the object (in this case, the operator's finger) is moved based on the output signals of the light receiving elements 12a and 12b. It can be detected without contact.

  Furthermore, since the outer side surfaces 4a and 5a are formed so as to form an angle equal to or greater than a right angle, the outer side surfaces 4a and 5a can easily enter the space even when wearing thick fingers or gloves, and the first and second optical axes L1. , L2 is blocked, so that the operator's hand can be detected reliably.

  On the first substrate 6, between the first light projecting element 11a and the second light receiving element 12b, light as a light guide means for guiding a part of the projection light from the light projecting element 11a to the light receiving element 12b. A waveguide 13a is provided. Similarly, on the second substrate 7, between the second light projecting element 11b and the first light receiving element 12a, light guiding means for guiding a part of the projection light from the light projecting element 11b to the light receiving element 12a. An optical waveguide 13b is provided.

  Therefore, the projection light from the first light projecting element 11a mounted on the first substrate 6 is the first light mounted on the second substrate 7 via the detection region A1 for detecting an object (a hand in the present embodiment). The light is received by the first light receiving element 12a and is received by the second light receiving element 12b mounted on the first substrate 6 without passing through the detection region A1. Similarly, the projection light from the second light projecting element 11b mounted on the second substrate 7 is received by the second light receiving element 12b mounted on the first substrate 6 via the detection area A1, and is detected in the detection area. The light is received by the first light receiving element 12a mounted on the second substrate 7 without passing through A1. That is, the optical axis L12 is formed between the first light projecting element 11a and the second light receiving element 12b, and the optical axis L21 is formed between the second light projecting element 11b and the first light receiving element 12a. 1 and 2 schematically show the detection region A1.

Next, the electrical configuration of the operation switch 1 will be described.
As shown in FIG. 3, the operation switch 1 includes a CPU 21, first and second light projecting circuits 22a and 22b, first and second light receiving circuits 23a and 23b, a detection comparator 24, a failure determination comparator 25, and an opening / closing means. 1 to 4 switches SW1 to SW4, first and second light projecting elements 11a and 11b, and first and second light receiving elements 12a and 12b. The circuit to which these are connected is configured by connecting electronic components (not shown) mounted on the first substrate 6 and the second substrate 7.

  First and second light projecting circuits 22a and 22b serving as light projecting means are connected to the CPU 21 serving as the drive means, the detecting means, the failure judging means, and the control means. The CPU 21 alternately outputs the first and second light projection signals P1 and P2 to the first and second light projection circuits 22a and 22b. First and second light projecting elements 11a and 11b are connected to the first and second light projecting circuits 22a and 22b, respectively. The first and second light projecting circuits 22a and 22b drive the first and second light projecting elements 11a and 11b in response to the first and second light projecting signals P1 and P2. Accordingly, the first and second light projecting elements 11a and 11b are alternately lit.

  As described above, the projection light from the first light projecting element 11a is received by the first and second light receiving elements 12a and 12b, and the projection light from the second light projecting element 11b is received by the first and second light receiving elements 12a, 12a. The light is received by 12b. The first and second light receiving elements 12a and 12b are respectively connected to first and second light receiving circuits 23a and 23b as light receiving means. The first and second light receiving circuits 23a and 23b output signals K1 and K2 corresponding to the currents flowing through the first and second light receiving elements 12a and 12b.

  The first light receiving circuit 23a is connected to the detection comparator 24 via the first switch SW1, and is connected to the failure determination comparator 25 via the third switch SW3. The second light receiving circuit 23b is connected to the detection comparator 24 through the second switch SW2, and is connected to the failure determination comparator 25 through the fourth switch SW4.

  The first to fourth switches SW1 to SW4 are connected to the CPU 21 and are turned on / off in response to control signals S1 to S4 output from the CPU 21. The CPU 21 uses the first to fourth switches SW1 to SW4 so that the output signals K1 and K2 of the first and second light receiving circuits 23a and 23b are complementarily input to the detection comparator 24 and the failure determination comparator 25. To control. More specifically, the CPU 21 turns on the first switch SW1 to input the output signal K1 of the first light receiving circuit 23a to the detection comparator 24, and turns on the fourth switch SW4 to output the signal from the second light receiving circuit 23b. K2 is input to the failure determination comparator 25. Further, the CPU 21 turns on the second switch SW2 to input the output signal K2 of the second light receiving circuit 23b to the detection comparator 24, and turns on the third switch SW3 to give the output signal K1 of the first light receiving circuit 23a. Input to the failure determination comparator 25.

  The detection comparator 24 compares the levels of the output signals K1 and K2 of the first or second light receiving circuits 23a and 23b with the detection determination level, and outputs a detection signal X1 corresponding to the comparison result. For example, the detection comparator 24 detects the H level detection signal X1 when the levels of the output signals K1 and K2 are equal to or higher than the detection determination level, that is, when the amount of light incident on the first or second light receiving element 12a or 12b is equal to or higher than a predetermined level. When the level of the output signals K1 and K2 is smaller than the detection determination level, that is, the incident light quantity is less than the predetermined level, the L level detection signal X1 is output.

  The CPU 21 determines the presence or absence of an object based on the detection signal X1 at the timing (determination period) corresponding to the first or second light projection signals P1 and P2. In the above example, the CPU 21 determines that no object exists on the optical axes L1 and L2 based on the detection signal X1 at the H level, and determines that an object exists on the optical axes L1 and L2 based on the detection signal X1 at the L level. .

  The failure determination comparator 25 compares the levels of the output signals K1 and K2 of the first or second light receiving circuits 23a and 23b with the failure determination level, and outputs a determination signal X2 corresponding to the comparison result. For example, the detection comparator 24 determines the H level determination signal X2 when the levels of the output signals K1 and K2 are equal to or higher than the failure determination level, that is, when the amount of light incident on the first or second light receiving element 12a, 12b is equal to or higher than a predetermined level. When the level of the output signals K1 and K2 is lower than the failure determination level, that is, the incident light quantity is lower than the predetermined level, the L level determination signal X2 is output.

  The CPU 21 determines whether or not there is a failure based on the determination signal X2. In the above example, the CPU 21 has incident light on the light receiving element at that time based on the H level determination signal X2, that is, the light emitting element at that time and the light receiving circuit and the light receiving element connected to the failure determination comparator 25 have failed. It is determined that it is not. On the other hand, the CPU 21 determines based on the L level determination signal X2 that there is no incident light in the light receiving element at that time, or that no signal is input to the light receiving circuit or the failure determination comparator 25, that is, a failure has occurred.

The operation of the operation switch 1 configured as described above will be described with reference to the timing chart of FIG.
At a predetermined timing, the CPU 21 outputs the first light projecting signal P1, and the first light projecting circuit 22a drives the first light projecting element 11a. Further, the CPU 21 outputs first and fourth control signals S1 and S4, connects the first light receiving circuit 23a to the detection comparator 24, and connects the second light receiving circuit 23b to the failure determination comparator 25.

  The projection light from the first light projecting element 11a enters the first light receiving element 12a when the object does not exist on the optical axis L1, and enters the first light receiving element 12a when the object exists on the optical axis L1. Not. Further, the projection light from the first light projecting element 11a is incident on the second light receiving element 12b via the optical waveguide 13a.

  When no object is present on the optical axis L1, the detection comparator 24 outputs an H level detection signal X1. Further, the failure determination comparator 25 outputs an H level determination signal X2. Therefore, the CPU 21 determines that no object exists based on the detection signal X1 at the H level. The CPU 21 determines that there is no failure based on the determination signal X2 at the H level.

  Next, the CPU 21 similarly outputs the second light projection signal P2, and the second light projection circuit 22b drives the second light projection element 11b. Further, the CPU 21 outputs the second and third control signals S2 and S3, connects the second light receiving circuit 23b to the detection comparator 24, and connects the first light receiving circuit 23a to the failure determination comparator 25.

  The projection light from the second light projecting element 11b enters the second light receiving element 12b when the object does not exist on the optical axis L2, and enters the second light receiving element 12b when the object exists on the optical axis L2. Not. Further, the projection light from the second light projecting element 11b is incident on the first light receiving element 12a through the optical waveguide 13b.

  When the object does not exist on the optical axis L2, the detection comparator 24 outputs an H level detection signal X1. Further, the failure determination comparator 25 outputs an H level determination signal X2. Therefore, the CPU 21 determines that no object exists based on the detection signal X1 at the H level. The CPU 21 determines that there is no failure based on the determination signal X2 at the H level.

  On the other hand, when the L level detection signal X1 and the H level determination signal X2 are input, the CPU 21 determines that there is no failure based on the determination signal X2, and based on the L level detection signal X1. It is determined that an object exists on the optical axis L1 (L2).

  When at least one of the first light projection signal P1 and the second light projection signal P2 is output and the L level determination signal X2 is input, the CPU 21 determines that a failure has occurred. For example, when an L-level discrimination signal X2 is input when the first light projection signal P1 is output, on the path through which the discrimination signal X2 is input from the CPU 21 via the first light projecting element 11a and the second light receiving element 12b. It can be determined that a failure or disconnection has occurred.

  Further, the failure location can be determined by using the detection signal X1. For example, when the first light projecting signal P1 is output and the H level detection signal X1 and the L level discrimination signal X2 are input, the projection light from the first light projecting element 11a is applied to the first light receiving element 12a. Incident. Therefore, it can be determined that a failure or disconnection occurs between the second light receiving element 12b and the CPU 21.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The operation switch 1 includes a plurality of sets of light projecting elements 11a and 11b and light receiving elements 12a and 12b. The pair of light receiving elements 12b and 12a can receive light. Then, the CPU 21 of the operation switch 1 sequentially projects the light projecting elements 11a and 11b of each group, and receives the light projecting elements 11a and 11b that are driven to project at the light projecting timing of each group. The detection object is detected based on the detection signal X1 output from the detection comparator 24 in accordance with the amount of received light 12a and 12b. Further, the CPU 21 determines a failure according to the amount of light received by the other light receiving elements 12b and 12a that receive a part of the projection light from the light projecting elements 11a and 11b that perform light emission driving at the light projection timing of each group. The failure is determined on the basis of the determination signal X2 output from the comparator 25.

  Therefore, when a detection object is detected by one set of light projecting element and light receiving element (for example, the light projecting element 11a and the light receiving element 12a), a part of the projection light from the light projecting element 11a. Is received by the light receiving element 12b by the optical waveguide 13a, and the failure is determined based on the amount of light received by the light receiving element 12b. Therefore, the failure can be determined while continuing the normal detection operation.

  (2) The light projecting elements 11a and 11b and the light receiving elements 12a and 12b are alternately arranged for each group, and the light projecting element 11a and the light receiving element 12b, the light projecting element 11b and the light receiving element 12a, which are adjacent to each other. Are provided with optical waveguides 13a and 13b for guiding a part of the projection light from the light projecting elements 11a and 11b to the light receiving elements 12b and 12a. Accordingly, since the projection light from the light projecting elements 11a and 11b can be directly received by the adjacent light receiving elements 12b and 12a, it is possible to determine a failure with little influence of disturbance light or the like.

  (3) Switches SW1 to SW4 are provided between the light receiving circuits 23a and 23b connected to the light receiving elements 12a and 12b and the detection comparator 24 and the failure determination comparator 25 to control the switches SW1 to SW4. Thus, the light receiving circuits 23a and 23b are sequentially switched and connected to the detection comparator 24 and the failure determination comparator 25. Therefore, it is not necessary to provide a detection comparator and a failure determination comparator for each of the light receiving circuits 23a and 23b, and an increase in the scale of the entire operation switch 1 can be suppressed.

In addition, you may implement each said embodiment in the following aspects.
In the above embodiment, the photoelectric sensor is embodied as an operation switch including two sets of light projecting elements 11a and 11b and light receiving elements 12a and 12b. However, the multi-light including three or more sets of light projecting elements and light receiving elements is provided. It may be embodied in an axial photoelectric sensor. In the case of a photoelectric sensor including three or more sets of light projecting elements and light receiving elements, a part of the projection light from the light projecting elements can be received by another adjacent light receiving element as in the above embodiment. It may be. Further, it is possible to receive the projection light from each light projecting element every two sets, that is, a plurality of configurations shown in FIG. 2 may be provided.

  In the above embodiment, the optical waveguides 13a and 13b guide the projection light from the light projecting elements 11a and 11b for the detection operation to the light receiving elements 12b and 12a that do not perform the detection operation without passing through the detection region A1. However, other light guiding means such as an optical fiber may be used.

  In the above embodiment, the first substrate 6 includes the light projecting element 11a, the light receiving element 12b, and the optical waveguide 13a, and the second substrate 7 includes the light projecting element 11b, the light receiving element 12a, and the optical waveguide 13b. However, as shown in FIG. 5, it is good also as a structure which equips the 1st board | substrate 6 with light projection element 11a, 11b, and equips the 2nd board | substrate 7 with light receiving element 12a, 12b. Then, a part of the projection light from the first light projecting element 11a is received by the second light receiving element 12b by an optical fiber (not shown) as a light guide means, and a part of the projection light from the second light projecting element 11b. May be received by the first light receiving element 12a.

  In the above-described embodiment, a so-called transmission type optical sensor in which the light projecting elements 11a and 11b and the light receiving elements 12a and 12b are arranged so as to detect the presence / absence of the detected object by the presence / absence of light blocking by the detected object The operation switch 1 used is embodied. In other words, it is an operation switch that can detect a detected object and detect a failure using a plurality of pairs of light projecting elements and light receiving elements, and the incident light amount of the light receiving element may be changed depending on the presence or absence of the detected object. An operation switch using a so-called reflection-type optical sensor that detects the presence or absence of the detection object based on the presence or absence of reflection of light by the detection object may be embodied. Further, the present invention may be embodied in an operation switch using a so-called limited reflection type optical sensor that detects the presence or absence of an object to be detected within a predetermined range from the light projecting element and the light receiving element. The configuration and operation for detecting a failure may be the same as those in the above embodiment.

  As shown in FIG. 6, light is emitted from the light projecting element 11a and the light receiving element 12a into the detection area A2, and the reflected light from the object to be detected in the detection area A2 enters the light receiving element 12a. To be arranged. Similarly, light is emitted from the light projecting element 11b and the light receiving element 12b to the detection area A2 from the light projecting element 11b, and the reflected light from the object to be detected in the detection area A2 is incident on the light receiving element 12b. Deploy. Further, the light projecting element 11a and the light receiving element 12b are arranged to face each other without using the detection area A2, and the light projecting element 11b and the light receiving element 12a are arranged to face each other without using the detection area A2. According to this configuration, as in the above-described embodiment, the light for failure determination is incident on the light receiving elements 12a and 12b without passing through the detection area A2, so that the detected object exists in the detection area A2. It is possible to receive failure determination light without being obstructed by the detected object even when the vehicle is being detected, that is, to perform failure determination while continuing normal detection operation. Furthermore, since the optical waveguides 13a and 13b in the above embodiment are not required, the number of parts is small, the manufacturing is easy, and the cost can be reduced.

  6 shows the arrangement of the light projecting elements 11a and 11b and the light receiving elements 12a and 12b with respect to the detection area A2, the optical axes L1 and L2 for detecting the detected object, and the optical axes L12 and L21 for determining the failure. Is schematically shown. When the arrangement relationship of the detection area, the light projecting elements 11a and 11b, and the light receiving elements 12a and 12b is applied to, for example, the photoelectric switch having the shape shown in FIGS. The light receiving element 12b is provided, and the light projecting element 11b and the light receiving element 12a are provided on the second substrate 7. The photoelectric switch shown in FIGS. 1 and 2 is merely an example, and it goes without saying that the outer shape of the photoelectric switch may be changed as appropriate.

  In the above embodiment, a plurality of sets of light projecting elements and light receiving elements are provided, and the detected object in the detection area is detected by each set of light projecting elements and light receiving elements. The optical axis for determining the failure may be formed without passing through the detection region, and the arrangement of the light projecting element and the light receiving element is not limited. For example, as shown in FIG. 7, a plurality of sets of light projecting elements 11a and 11b and light receiving elements 12a and 12b that constitute a transmission type optical sensor are arranged in different sets of light projecting elements 11a and 12b, and light projecting elements. 11b and the light receiving element 12a are arranged to face each other without the detection region A2. In FIG. 7, the optical axes L1 and L2 formed to detect the detection object intersect within the detection area A2, but the two light projecting elements 11a and 11b are alternately controlled to project light. Will not interfere. According to this configuration, as in the above-described embodiment, the light for failure determination is incident on the light receiving elements 12a and 12b without passing through the detection area A2, so that the detected object exists in the detection area A2. The failure determination light can be received without being interrupted by the object to be detected, that is, the failure determination can be performed while continuing the normal detection operation. Furthermore, since the optical waveguides 13a and 13b in the above embodiment are not required, the number of parts is small, the manufacturing is easy, and the cost can be reduced.

  7, as in FIG. 6, the arrangement of the light projecting elements 11 a and 11 b and the light receiving elements 12 a and 12 b with respect to the detection area A <b> 2, the optical axes L <b> 1 and L <b> 2 for detecting an object to be detected, and failure determination These optical axes L12 and L21 are schematically shown, and needless to say, they are arranged according to the outer shape of the photoelectric switch.

The side view which shows schematic structure of an operation switch. The front view which shows schematic structure of an operation switch. The block diagram which shows the electric constitution of an operation switch. The timing chart which shows operation | movement of an operation switch. Explanatory drawing which shows arrangement | positioning of a light projection element and a light receiving element. Explanatory drawing which shows arrangement | positioning of another light projecting element and a light receiving element. Explanatory drawing which shows arrangement | positioning of another light projecting element and a light receiving element.

Explanation of symbols

  11a, 11b ... light projecting element, 12a, 12b ... light receiving element, 13a, 13b ... optical waveguide, 21 ... CPU, 22a, 22b ... light projecting circuit, 23a, 23b ... light receiving circuit, 24 ... detection comparator, 25 ... failure Discriminating comparator, A1, A2... Detection region, SW1 to SW4... Switch, P1, P2... Projection light, X1.

Claims (6)

A photoelectric sensor comprising a plurality of sets of light projecting means for irradiating light toward the detection area and light receiving means for receiving light from the detection area in pairs with the light projecting means, and detecting an object to be detected in the detection area In
A part of light from the light projecting means of each set can be received by the light receiving means of a set different from the light projecting means without passing through the detection region
Driving means for sequentially projecting and driving each set of light projecting means;
Detecting means for detecting an object to be detected based on the amount of light received by the light receiving means paired with the light projecting means driven by light projection at each set of light projection timing;
A failure determination means for performing a failure determination based on the amount of light received by another set of light receiving means capable of receiving a part of the light of the light projecting means to be projected and driven at the light projection timing of each set;
A photoelectric sensor comprising: The photoelectric sensor according to claim 1,
Each set of light projecting means and light receiving means are arranged to face each other with the detection area interposed therebetween. The photoelectric sensor according to claim 2,
The photoelectric sensor, wherein the light projecting means and the light receiving means are alternately arranged for each set. In the photoelectric sensor as described in any one of Claims 1-3,
A photoelectric sensor comprising a light guide means for guiding a part of light from the light projecting means to the light receiving means between adjacent pairs of light projecting means and light receiving means. In the photoelectric sensor as described in any one of Claims 1-3,
The light projecting means of each set is disposed opposite to the other light receiving means without the detection area,
Each set of the light receiving means is disposed to face another set of light projecting means without passing through the detection area. In the photoelectric sensor as described in any one of Claims 1-5,
A comparator for detection that compares an output signal level of the light receiving means with a comparison determination level, and outputs a detection signal according to the comparison result;
A failure determination comparator that compares the output signal level of the light receiving means and a failure determination level, and outputs a determination signal according to the comparison result;
Opening / closing means connected to each of the light receiving means of each set, the detection comparator and the failure determination comparator,
Each set of light receiving means is connected to the detection comparator in turn, and another set in which a part of the light from the light projecting means arranged opposite to the light receiving means connected to the detection comparator can be received. Control means for controlling the opening and closing means to connect the light receiving means to the failure determination comparator,
A photoelectric sensor comprising:

Images