JP2008277163A - Multiple optical-axis photoelectric sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multiple optical-axis photoelectric sensor capable of easily confirming results of a countermeasure implemented against interference light. <P>SOLUTION: The multiple optical-axis photoelectric sensor has a normal operation mode, and a test mode. In the normal operation mode, a light-receiving control circuit 45 performs an interference light detection action on the basis of an interference light determination standard established as a normal standard. In the test mode, the light-receiving control circuit 45 performs an interference light detection action on the basis of an interference light determination standard established at a low standard lower than the normal standard. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multi-optical axis photoelectric sensor.

  Conventionally, a multi-optical axis photoelectric sensor for detecting that an object has entered a detection area is known. In the multi-optical axis photoelectric sensor, a light projector provided with a plurality of light projecting elements and a light receiver provided with a plurality of light receiving elements corresponding to each light projecting element are arranged to face each other. The light projecting element provided in the light projector repeatedly performs the light projecting scanning operation in which light is projected sequentially at a predetermined light projecting timing at a predetermined cycle, and based on the light receiving signal from the light receiving element corresponding to each light projecting element. Thus, an object intrusion into the detection area is detected.

  By the way, many detection areas are set in a production line of a factory, and a multi-optical axis photoelectric sensor is installed in each detection area. In such a case, there is a concern about the mutual interference that light from the light projecting element of the multi-optical axis photoelectric switch enters the light receiving element of another multi-optical axis photoelectric switch as interference light. As a result, there is a possibility that the optical axis formed by the light receiving element cannot be detected even though it is blocked. Further, in a place where a plurality of production devices are installed like a factory, there is a possibility that the reflected light from the devices may be incident as interference light. For this reason, some multi-optical axis photoelectric sensors include interference light detection means for detecting interference light (see, for example, Patent Document 1).

As a method of preventing the incidence of interference light, a slit is provided in front of the light projecting element so that the light beam is narrowed so that the light does not reach other multi-optical axis photoelectric switches, or in front of the light receiving element. In some cases, the slit is provided to limit the range of light incident on the light receiving element, thereby avoiding the influence of interference light. These measures are implemented by an operator visiting the installation location of the multi-optical axis sensor.
JP 2006-242572 A

  However, whether or not the above measures are appropriate can be confirmed only by the fact that the multi-optical axis photoelectric sensor does not detect interference light. For this reason, if the position or width of the slit is not appropriate, it can be confirmed after several hours by taking countermeasures, or after several days or even weeks (the multi-optical axis photoelectric sensor detects interference light). Become. Therefore, when the countermeasure is not appropriate, it takes time and effort to confirm the situation or to go to the installation location again and implement a new countermeasure. Moreover, the production line is stopped for the user of the multi-optical axis photoelectric sensor.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a multi-optical axis photoelectric sensor capable of easily confirming the result of countermeasures taken against interference light. .

  In order to achieve the above object, the invention described in claim 1 includes a plurality of light projecting elements, a plurality of light receiving elements provided so as to constitute a plurality of optical axes facing each of the light projecting elements, Light projecting control means for performing a light projecting scan operation for lighting a plurality of light projecting elements at a predetermined timing, and lighting timing of the light projecting elements that form the optical axis opposite to the light reception signals from the respective light receiving elements The light-shielding detection means for detecting the light-shielding state on the optical axis by detecting the light-shielding light, the output means for outputting an output signal based on the light-shielding state from the light-shielding detection means, and the light emitting elements in a predetermined range are turned on Interference light detection means for performing an interference light detection operation for detecting the presence of interference light based on a light reception signal from the light receiving element facing the light projecting element set in advance in the predetermined range in the predetermined range; , The multi-optical axis photoelectric sensor includes a normal operation mode and a test mode, and in the normal operation mode, the interference light detection unit determines an interference light determination period, an interference light determination threshold, and the interference light. The interference light detection operation is performed based on an interference light determination criterion set as a normal reference including a frequency determination value for determining the number of times as abnormal. In the test mode, the interference light detection means includes the interference light determination period and The interference light detection operation is performed based on an interference light determination standard in which at least one of the interference light determination threshold value and the number of times determination value is set to a low standard lower than the normal standard.

  According to this configuration, when the operator operates the multi-optical axis photoelectric sensor in the test mode, the interference light determination standard is lower than that in the normal operation, and the environment is more likely to malfunction than in the normal operation. The operator can easily and accurately confirm the disturbance light incident state in the set state and the quality of disturbance light countermeasures in a shorter time than the normal operation.

  The low standard lower than the normal standard is a standard set to a value at which interference light is easier to detect than the normal standard. The interference light is easily detected by performing at least one of increasing the interference light determination period, lowering the interference light determination threshold, and decreasing the number of times determination value. The interference light determination period is a period during which a received light signal is captured. Increasing this period can be achieved by increasing the continuous time and performing capturing for a predetermined period multiple times.

  According to a second aspect of the present invention, in the multi-optical axis photoelectric sensor according to the first aspect, the normal operation mode and the test mode are switched by an external device connected externally. According to this configuration, it is possible to prevent inadvertent switching to the test mode.

  According to a third aspect of the present invention, in the multi-optical axis photoelectric sensor according to the first or second aspect of the present invention, when the interference light is detected, a notification means for notifying the fact is provided. According to this configuration, the operator can easily know the detection of the interference light.

  According to a fourth aspect of the present invention, in the multi-optical axis photoelectric sensor according to the third aspect of the present invention, the multi-optical axis photoelectric sensor includes a display unit that indicates a position of the light receiving element that detects the interference light. According to this configuration, the light receiving element on which the interference light is incident can be easily confirmed, and a countermeasure can be implemented.

  A fifth aspect of the present invention is the multi-optical axis photoelectric sensor according to the fourth aspect, wherein the display means is provided for each of the light receiving elements. According to this configuration, it is possible to easily identify the light receiving element on which the interference light is incident, and to take measures against the interference light.

  A sixth aspect of the present invention is the multi-optical axis photoelectric sensor according to the fourth or fifth aspect, wherein the display mode of the display means is changed according to the amount of the interference light. According to this configuration, it is possible to implement a countermeasure according to the amount of incident interference light in the light receiving element.

  A seventh aspect of the present invention is the multi-optical axis photoelectric sensor according to any one of the first to sixth aspects, wherein the interference light detection means is in a light-shielded state on each optical axis by the light-shielding detection means. The interference light detection operation is performed in at least one period before and after the detection. According to this configuration, the interference light detection operation for each light receiving element can be reliably performed.

  As described above, according to the present invention, it is possible to provide a multi-optical axis photoelectric sensor capable of easily confirming a countermeasure result taken against interference light.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the multi-optical axis photoelectric sensor includes a light projector 10 and a light receiver 20 that are arranged to face each other.

  The projector 10 has a main body case 10a having a substantially U-shaped cross section made of a long body, and includes a basic unit 30 and a desired number (three in this example) of extension units 31 inside the main body case 10a. A plurality of units are detachably accommodated. The basic unit 30 and the extension unit 31 each have a prismatic shape, the extension unit 31 is connected to the upper end surface of the basic unit 30, and another extension unit 31 is connected to the upper end surface of the extension unit 31. Thus, the units 30 and 31 are connected in series. End caps 10b and 10c are provided at both ends of the main body case 10a, and each unit in the main body case 10a is fitted by fitting the end caps 10b and 10c at both ends in a state where the units 30 and 31 are accommodated in the main body case 10a. The positions 30, 31 are held. In the present embodiment, each of the basic unit 30 and the extension unit 31 corresponds to a “light projecting unit”. The main body case 10a and the end caps 10b and 10c constitute a “first case”.

  The basic unit 30 and the extension unit 31 are provided with, for example, four light projecting elements 32 made of light emitting diodes (LEDs) arranged in a line in the longitudinal direction (vertical direction in the drawing). The light projecting elements 32 are positioned in a straight line when the units 30 and 31 are connected to each other.

  Similar to the projector 10, the light receiver 20 has a main body case 20a having a substantially U-shaped cross section made of an elongated body. Inside the main body case 20a, the basic unit 40 and a desired number (three in this example) are provided. A plurality of units including the additional unit 41 are detachably accommodated. Each of the basic unit 40 and the extension unit 41 has a prismatic shape, the extension unit 41 is connected to the upper end surface of the basic unit 40, and another extension unit 41 is connected to the upper end surface of the extension unit 41. Thus, the units 40 and 41 are connected in series. End caps 20b and 20c are provided at both ends of the main body case 10a, and the end caps 20b and 20c are fitted at both ends in a state in which the units 40 and 41 are accommodated in the main body case 20a. The positions 40 and 41 are held. In the present embodiment, each of the basic unit 40 and the extension unit 41 corresponds to a “light receiving unit”. The main body case 20a and the end caps 20b and 20c constitute a “second case”.

  In the basic unit 40 and the extension unit 41, for example, four light receiving elements 42 made of photodiodes (PD) are arranged in a line in the longitudinal direction (vertical direction in the drawing), for example. When the units 40 and 41 are connected to each other, the light receiving elements 42 are positioned and held in a state of being aligned on a straight line. In addition, when distinguishing the extension units 41 connected up and down, “a”, “b”, and “c” are added to the end of the code in order from the extension unit 41 on the upper end side.

  Each light projecting element 32 disposed in the light projector 10 and each light receiving element 42 disposed in the light receiver 20 are paired with each other, with elements disposed in the same order in the vertical direction being a normal counterpart. The optical axis L is formed by the elements.

  For example, in the present embodiment, 12 light projecting elements 32 and 12 light receiving elements 42 form 12 optical axes L sequentially in a time-division manner at a predetermined timing. A detection area within a predetermined range is set between 10 and the light receiver 20. If there is an object to be detected in this detection area, the light passing between the projector 10 and the light receiver 20 will be blocked. At that time, if one of the 12 optical axes mentioned above is also blocked. A detection signal indicating that a detected object exists in the detection area is output to an external device (not shown).

  The basic unit 40 of the light receiver 20 is provided with a display lamp 43 as a notification means and a display means on the side surface on which the light receiving element 42 is disposed. As shown in FIG. 2, the indicator lamp 43 includes a plurality of (for example, four) display units 43a to 43d. Each display part 43a-43d consists of a 2 color light emitting diode (LED) which light-emits red and green, for example, respectively, and displays the operation state of each unit 40 and 41. FIG. For example, when the units 40 and 41 are operating normally, the display units 43a to 43d corresponding to the units 40 and 41 emit green light. On the other hand, when the interference light is detected, the display units 43a to 43d corresponding to the unit that detected the interference light are blinked in red.

FIG. 2 is a block diagram showing an electrical configuration of the multi-optical axis photoelectric sensor.
Each of the basic unit 30 and the extension unit 31 of the projector 10 is provided with one projector circuit 33 connected to each of the four projector elements 32, and each projector circuit 33 is connected to each of the units 30 and 31. Electrical connection is made via a connector (not shown) provided in the connection portion. Each light projecting circuit 33 operates based on a timing signal from a light projecting control circuit 34 serving as a light projecting control unit including a CPU or the like provided in the basic unit 30. For example, the light projecting element 32 on the upper end side of the projector 10. The operation of sequentially supplying a drive signal from the light source to the light projecting element 32 on the lower end side is repeated at a high cycle. Thereby, an optical signal is sequentially emitted from the light projecting element 32 on the upper end side of the projector 10 in a time division manner.

  On the other hand, each of the basic unit 40 and the extension unit 41 of the light receiver 20 is provided with one light receiving circuit 44 connected to each of the four light receiving elements 42, and each light receiving circuit 44 corresponds to each of the units 40 and 41. Electrical connection is made via a connector (not shown) provided in the connection portion.

  Here, although not shown in the figure, each light receiving circuit 44 is provided with four switch elements connected to the four light receiving elements 42 and one shift register connected to the switch elements. A drive signal from a light receiving control circuit 45 as a light shielding detecting means, an output means, and an interference light detecting means comprising a CPU or the like provided in the above is sequentially given to each switch element via a shift register of each light receiving circuit 44. It is like that. At that time, each switch element is always in an off state, and the light reception signal of the light reception element 42 connected to the switch element turned on by the drive signal supplied from the light reception control circuit 45 is sequentially taken into the light reception control circuit 45. It has become.

  More specifically, the light receiving control circuit 45 takes in the timing signal from the light projecting control circuit 34 via the line 50 connecting the basic unit 30 of the projector 10 and the basic unit 40 of the light receiver 20, and this timing. A predetermined switch element is turned on in response to the signal. The light projection control circuit 34 includes a light shielding detection timing signal Sr whose period and phase coincide with those of the light projection timing signal St, an interference light detection timing signal Si whose phase is slightly advanced from the light shielding detection timing signal Sr, and the signal. The interference light detection timing signal Sj whose phase is slightly delayed from Sr is transmitted to the light reception control circuit 45.

  The light reception control circuit 45 that has received the light shielding detection timing signal Sr and the interference light detection timing signals Si and Sj faces the light projecting element 32 in correspondence with the timing at which the light projecting element 32 at a predetermined position projects the optical signal. The switch element connected to the light receiving element 42 to be turned on is turned on. A light reception signal output from the light receiving element 42 via the switch element that has been turned on is taken into the light reception control circuit 45 via the light receiving circuit 44.

  Then, when the light reception control circuit 45 receives the light shielding detection timing signal Sr, each light projecting element 32 is in a lighting state, so that the light reception detection (detection / non-detection of the detected object) is performed depending on the presence or absence of the light reception signal from the light receiving element 42. Detection). Specifically, the light reception control circuit 45 sequentially checks the magnitude relation between the light reception determination threshold and the received light reception signal. Then, the light reception control circuit 45 does not detect an object to be detected between the projector 10 and the light receiver 20 when the light reception signals of all the light receiving elements 42 in the extension unit 41a exceed the light reception determination threshold (non-detection). If any one of the received light signals falls below the reference voltage, it is determined that an object to be detected exists (detected) between the projector 10 and the light receiver 20. The light reception control circuit 45 detects the detected object entering the detection area in this way, and outputs a detection signal of a level according to whether or not the detected object is detected to the outside (external device). For example, the light reception control circuit 45 outputs a detection signal of H level when detecting the detected object and L level when not detecting.

  Further, when receiving the interference light detection timing signals Si and Sj, the light reception control circuit 45 detects the interference light depending on the presence or absence of the light reception signal from the light receiving element 42 because the light projecting element 32 is in a non-lighting state. Specifically, the light reception control circuit 45 sequentially checks the magnitude relationship between the interference light determination threshold and the captured light reception signal. Then, when the light reception signal of the light receiving element 42 exceeds the interference light determination threshold value, the light reception control circuit 45 determines that interference light is incident on the light receiving element 42 (detection), and the light reception signal interferes. If it falls below the light determination threshold, it is determined that no interference light is incident on the light receiving element 42 (non-detection). The light reception control circuit 45 detects the presence or absence of interference light with respect to each light receiving element 42 in this way, and blinks the display units 43a to 43d corresponding to the light receiving element 42 that has detected the interference light. Note that a signal corresponding to detection / non-detection of interference light may be output to the outside (external device). That is, a circuit that outputs a signal corresponding to the detection / non-detection of the interference light may be provided as a notification unit.

  An external device (external controller) 70 is connected to the light reception control circuit 45. The external device 70 is connected to switch the operation mode of the light reception control circuit 45 between the normal operation mode and the test mode. In the normal operation mode, the light reception control circuit 45 sets the interference light determination criterion including the interference light determination threshold as a normal reference, and performs light shielding detection and interference light detection. On the other hand, in the test mode, the light reception control circuit 45 sets the above-described interference light determination reference to a low reference lower than the normal reference, and performs light shielding detection and interference light detection. In the present embodiment, the interference light determination criteria are interference light determination periods S1 and S2, in which interference light is captured, interference light determination thresholds J1 and J2, and the number of times determination value K. A low standard means that it is easy to detect interference light. The low criterion is a criterion in which at least one of the interference light determination periods S1 and S2, the interference light determination thresholds J1 and J2, and the number of times determination value K is set to a value at which interference light is easier to detect than the normal reference. is there. For example, if the interference light determination periods S1 and S2 are lengthened, the light reception level in the light receiving element 42 is likely to increase, and is likely to be larger than the interference light determination thresholds J1 and J2. If the interference light determination thresholds J1 and J2 are set to small values, even a small amount of light is detected as interference light. The light reception control circuit 45 counts the number of times that the light reception signal is determined to be larger than the interference light determination thresholds J1 and J2, and when the number of times becomes equal to or greater than the number of times determination value K, the light reception control circuit 45 performs abnormal output as detecting the interference light. Therefore, if the number-of-times determination value K is set to a small value, the period until it is determined that interference light has been detected is shortened. By detecting the interference light with a low standard, it becomes easy to detect the interference light, that is, the result of the countermeasure against the interference light can be confirmed in a short time.

Next, a light receiving process for performing the above-described light blocking detection and interference light detection will be described with reference to FIGS.
In step 81, the light reception control circuit 45 determines whether or not the operation mode is the test mode. When the operation mode is the normal operation mode, the process proceeds to step 82. When the operation mode is the test mode, the process proceeds to step 83.

  In step 82, the light reception control circuit 45 sets the interference light determination reference to the normal reference. On the other hand, in step 83, the light reception control circuit 45 sets the interference light determination criterion to a low criterion.

  Next, in step 84, the light reception control circuit 45 determines whether or not it is the interference light detection timing 1 based on the interference light detection timing signal Si. That is, the light reception control circuit 45 waits until an interference light detection timing signal Si of a predetermined level is input, and when the interference light detection timing signal Si is input, the process proceeds to step 85.

  In step 85, the light reception control circuit 45 takes in the light reception signal in the interference light determination period S1. Next, in step 86, the light reception control circuit 45 compares the light reception signal with the interference light determination threshold value J1, and determines whether interference light is received based on the comparison result. The light reception control circuit 45 stores the determination result in a storage means (not shown).

  In step 87, the light reception control circuit 45 determines whether it is a light reception detection timing based on the light shielding detection timing signal Sr. That is, the light reception control circuit 45 waits until the light shielding detection timing signal Sr of a predetermined level is input, and proceeds to Step 88 when the light shielding detection timing signal Sr is input.

  In step 88, the light reception control circuit 45 takes in the light reception signal of the light reception period T. Next, at step 89, the light reception control circuit 45 compares the light reception signal with a light reception (light shielding) determination threshold value H and stores the comparison result in a storage means (not shown).

  In step 90, the light reception control circuit 45 determines whether or not it is the interference light detection timing 2 based on the interference light detection timing signal Sj. That is, the light reception control circuit 45 waits until an interference light detection timing signal Sj of a predetermined level is input. When the interference light detection timing signal Sj is input, the process proceeds to step 91.

  In step 91, the light reception control circuit 45 takes in the light reception signal in the interference light determination period S2. Next, in step 92, the light reception control circuit 45 compares the light reception signal with the interference light determination threshold value J2, and determines whether interference light is received based on the comparison result. The light reception control circuit 45 stores the determination result in a storage means (not shown).

  In step 93, the light reception control circuit 45 determines whether or not the determination on the number N of optical axes has been completed. N at this time is the number of optical axes L formed between the light projector 10 and the light receiver 20, that is, the number of pairs of the light projecting element 32 and the light receiving element 42. That is, the light reception control circuit 45 repeatedly executes the processing of steps 84 to 92 for each of all the optical axes L of the multi-optical axis photoelectric sensor. When the determination is completed for all the optical axes L, the light reception control circuit 45 proceeds to Step 94.

  In step 94, the light reception control circuit 45 reads out the determination results in steps 86 and 92 from the storage means. If interference light is detected in steps 86 and 92, the process proceeds to step 95, and no interference light is detected. Then, the process proceeds to step 96.

  In step 95, the light reception control circuit 45 determines whether or not there is interference light detection equal to or greater than the number of times determination value K on the same optical axis. That is, the light reception control circuit 45 counts the number of times interference light is detected on each optical axis, and stores the count value in a storage unit (memory) (not shown). The light reception control circuit 45 proceeds to step 96 when the count value for each optical axis is smaller than the number determination value K, and proceeds to step 97 when the count value is greater than or equal to the number determination value K.

  In step 96, the light reception control circuit 45 reads the comparison result of step 89 from the storage means, and performs object detection determination based on the comparison result. Based on the determination result, the light reception control circuit 45 outputs a signal corresponding to whether or not the detected object is detected (the presence or absence of light shielding by the detected object).

  In step 97, the light reception control circuit 45 performs an abnormal output, that is, blinks the light emitting units 43a to 43d (see FIG. 2) corresponding to the position of the light receiving element 42 that has detected the interference light. 1 and 2, the light receiver 20 includes four units 40 and 41a to 41c, and each of the units 40 and 41a to 41c is provided with four light receiving elements 42, respectively. Therefore, each light receiving element 42 of the unit 40 corresponds to the display unit 43a, each light receiving element 42 of the unit 41c corresponds to the display unit 43b, each light receiving element 42 of the unit 41b corresponds to the display unit 43c, Each light receiving element 42 of the unit 41c corresponds to the display unit 43d. For example, when the light receiving control circuit 45 detects the incidence of interference light in the light receiving element 42 of the unit 41c, the light receiving control circuit 45 blinks the display unit 43d in red.

  An operator who executes processing corresponding to the interference light of the multi-optical axis photoelectric sensor causes the light receiver 20 (light reception control circuit 45) to be executed in the test mode by the external device 70 shown in FIG. And the interference which visually recognizes display part 43a-43d and attaches the board which formed the slit, for example to the light projector 10 and the light receiver 20 with respect to the light receiving element 42 of the position corresponding to the display part 43a-43d. Implement light countermeasures.

  As described above, in the test mode, the interference light determination criterion is set to a low criterion. Therefore, it is easy to detect the interference light, that is, the result of the countermeasure can be confirmed in a short time.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The multi-optical axis photoelectric sensor of this embodiment includes a normal operation mode and a test mode. In the normal operation mode, the light reception control circuit 45 performs interference light based on the interference light determination criterion set as the normal reference. In the test mode, the light reception control circuit 45 performs the interference light detection operation based on the interference light determination standard set to a low standard lower than the normal standard.

  As a result, when the operator operates the multi-optical axis photoelectric sensor in the test mode, the interference light judgment standard lower than the normal operation is set in an environment where the malfunction is more likely to occur than in the normal operation. The operator can easily and accurately confirm the disturbance light incident state in the set state and whether the disturbance light countermeasures are good or bad in a shorter time.

  (2) The interference light determination criterion includes a determination period for capturing the interference light, a determination threshold value to be compared with the interference light, and a frequency determination value for determining the number of times the interference light has been determined to be abnormal. And at least one of the number determination values is changed. For this reason, a low reference lower than the normal reference can be easily set, and interference light can be easily detected.

(3) The normal operation mode and the test mode are switched by the external device 70 connected externally. For this reason, it is possible to prevent inadvertent switching to the test mode.
(4) An indicator lamp 43 indicating the position of the light receiving element that detected the interference light is provided. For this reason, it is possible to easily confirm the light receiving element on which the interference light is incident, and to take countermeasures.

In addition, you may implement the said embodiment in the following aspects.
In the above embodiment, the presence or absence of interference light with respect to the basic unit 40 and the extension unit 41 (41a to 41c) is displayed by the indicator lamp 43 provided in the basic unit 40. As shown in FIG. Each unit 101a to 101c may be provided with an indicator lamp 102 to output the presence or absence of interference light in each unit 41a to 41c. Furthermore, an indicator lamp may be provided for each light receiving element 42, and the light receiving element 42 on which the interference light enters can be identified more easily.

  In the above embodiment, the number of extension units 31 and 41, the number of light projecting elements 32 of each unit 30 and 31, the number of light receiving elements 42 of each unit 40 and 41, and the indicator lamp 43 provided in the basic unit 40 You may implement by changing suitably the number of the display parts to comprise, the number of the display parts 43a-43d which comprise the indicator lamp 43, etc.

  In the above embodiment, the external device 70 is connected to the light receiver 20, and the operation mode of the light receiver 20 is switched between the normal operation mode and the test mode by the external device 70. You may make it set the operation mode of the light receiver 20 from the external device which receives the detection signal to output.

  In the above embodiment, the indicator lamp 43 is provided in the basic unit 40, but may be provided in the external device 70. Since the position of the light receiving element that has detected the interference light only needs to be confirmed in the test mode, it is not necessary to provide the indicator lamp 43 in the basic unit 40, and the configuration of the basic unit 40 can be simplified.

  In the above embodiment, the projector 10 is configured by connecting the basic unit 30 and the extension unit 31, and the light receiver 20 is configured by connecting the basic unit 40 and the extension unit 41. You may comprise by.

  In the above embodiment, the display mode of the indicator lamp 43 may be changed according to the level of the received light signal in the interference light determination period, that is, the incident light amount of the interference light. To change the display correspondence, change the blinking period, change the number of blinks in a certain time, change the lighting intensity, change the number of display elements (LED, etc.) that blink according to the level of the received light signal, Including signal level numerically. In this way, the operator can easily confirm the incident light amount of the interference light, and can take measures according to the incident light amount.

  In the above embodiment, the indicator lamp 43 is provided as a notification means with a circuit that outputs a signal corresponding to the detection / non-detection of interference light, but other means (for example, sound) are provided. Also good.

  In the above embodiment, the interference light detection operation is performed in the period (steps 84 to 86, 90 to 92) before and after performing the light shielding detection (steps 87 to 89). An interference light detection operation may be performed. Further, an interference light detection operation may be performed in a preset light receiving element.

  In the above embodiment, the interference light detection operation is performed during one projection scan operation. However, the interference light detection operation is performed between the projection scan operation and the next projection scan operation. It may be. Further, the interference light detection operation may be performed for each of a plurality of light projection scanning operations.

  In the above embodiment, the interference light determination periods S1 and S2 are lengthened to facilitate the detection of the interference light, but the interference light determination period is made constant and the number of the interference light determination periods is changed. You may make it lengthen the period which takes in the light reception signal from a light receiving element in the period when the light projection element is not substantially lighting.

  In the embodiment described above, the interference light determination operation may be performed in the light receiving element that is not affected by the lit light projecting element. That is, the range affected by the light-projecting element in one multi-optical axis photoelectric sensor is known in advance. For this reason, the interference light detection operation may be performed in a period in which the light projecting element within the range (predetermined range) that is not affected is not lit.

The perspective view which shows the multi-optical axis photoelectric sensor of one Embodiment. The block diagram which shows the electrical constitution of a multi-optical axis photoelectric sensor. The flowchart of a light reception process. The flowchart of a light reception process. The perspective view which shows another multi-optical axis photoelectric sensor.

Explanation of symbols

  32 ... Light projecting element, 34 ... Light projecting control circuit, 42 ... Light receiving element, 43 ... Indicator lamp, 45 ... Light receiving control circuit, 70 ... External device, S1, S2 ... Interference light determination period, J1, J2 ... Interference light determination Threshold value, K: number of times determination value, L: optical axis.

Claims (7)

A plurality of light emitting elements;
A plurality of light receiving elements provided to constitute a plurality of optical axes facing each light projecting element;
Projection control means for performing a projection scan operation for lighting the plurality of projection elements at a predetermined timing;
A light-blocking detection means for detecting a light-blocking state on the optical axis by detecting a light-receiving signal from each of the light-receiving elements so as to coincide with a lighting timing of a light projecting element that forms the optical axis facing the light-receiving signal;
An output means for outputting an output signal based on a light shielding state from the light shielding detection means;
Interfering light that detects the presence of interference light based on a light receiving signal from the light receiving element facing the preset light projecting element in the predetermined range during a period when the light projecting element in the predetermined range is not lit. Interference light detecting means for performing detection operation;
A multi-optical axis photoelectric sensor comprising:
It has a normal operation mode and a test mode,
In the normal operation mode, the interference light detection means includes an interference light determination period, an interference light determination threshold, and an interference light determination criterion set as a normal reference including a number of times determination value for determining the number of times the interference light is determined as abnormal. The interference light detection operation is performed based on
In the test mode, the interference light detection means includes an interference light determination criterion in which at least one of the interference light determination period, the interference light determination threshold, and the number of times determination value is set to a low reference lower than the normal reference. The interference light detection operation is performed based on
A multi-optical axis photoelectric sensor.   The multi-optical axis photoelectric sensor according to claim 1, wherein the normal operation mode and the test mode are switched by an external device connected externally.   The multi-optical axis photoelectric sensor according to claim 1, further comprising an informing means for informing when the interference light is detected.   4. The multi-optical axis photoelectric sensor according to claim 3, wherein the notifying means is a display means for indicating a position of a light receiving element that detects the interference light.   The multi-optical axis photoelectric sensor according to claim 4, wherein the display unit is provided for each of the light receiving elements.   6. The multi-optical axis photoelectric sensor according to claim 4, wherein a display mode of the display unit is changed according to the amount of the interference light.   The interference light detection means performs an interference light detection operation in at least one period before and after detection of a light shielding state on each optical axis by the light shielding detection means. The multi-optical axis photoelectric sensor according to one item.

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