Light curtain

Abstract

Wiring efficiency is improved in a case where an operating indicator light is provided on a light curtain of an optical synchronization system. The light curtain includes a synchronization unit (optical axis for time synchronization) that synchronizes the light projection time of a light transmitter and the light reception time of a light receiver via optical communication. A safety signal, generated based on whether the optical axis formed between the light transmitter and the light receiver is in a light-shielding state or not, is transmitted to an external system.The light curtain comprises a first operating indicator lamp provided in the light transmitter, a second operating indicator lamp provided in the light receiver, optical elements (optical axes) provided and configured in each of the light transmitter and the light receiver to lock and indicate the first operating indicator lamp and the second operating indicator lamp, and a control circuit configured to lock and indicate the first operating indicator lamp and the second operating indicator lamp using the at least one set of optical elements.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The invention relates to a light curtain. 2. Description of the state of the art

[0002] A light curtain is an aspect of a multi-optical-axis photoelectric sensor. The light curtain detects a person or object depending on whether a multitude of optical axes formed between a light emitter and a light receiver are blocked or not.

[0003] Some light curtains include a power indicator light. The power indicator light is used, for example, to indicate information such as (1) a power supply being on or off, (2) an output signal switching device (OSSD) being on or off, that is, a light receiving state and a light shielding state, and (3) a fault state. For example, the power indicator light is off when all of a plurality of light receiving elements provided in a light receiver are receiving light beams emitted by a plurality of light projection elements provided in a light emitter, and is on otherwise. Furthermore, the power indicator light also changes to an on state when a fault occurs in the light curtain.A worker can visually determine the operating status of the light curtain by looking at the operating indicator light of the light curtain.

[0004] Furthermore, with a light curtain, it is necessary to coordinate the control times of the light projection element and the light reception element; that is, to synchronize the light projection time and the light reception time, with regard to the detection principle of an optical axis. Two types of synchronization systems have become known: a wired synchronization system and an optical synchronization system.

[0005] In a wired synchronization system, the light source and receiver are connected by a cable, and the light projection and reception times are synchronized via wired communication over the cable. Wired synchronization systems are more resistant to mutual light interference than optical synchronization systems. However, wired synchronization systems require significant cabling work. This becomes particularly complex when the light source and receiver are physically separated.

[0006] In an optical synchronization system, a synchronization pulse is projected from the light source. This pulse signal, used for time synchronization, has a unique pulse pattern. The light receiver synchronizes its light reception time with the light projection time of the synchronization pulse. The optical synchronization system requires no wiring between the light source and receiver and offers greater flexibility in wiring configuration. However, it is less susceptible to mutual light interference than a wired synchronization system.

[0007] Note that in recent years, to improve resistance to mutual light interference, redundancy of detection pulses has been promoted by increasing the speed of a detection circuit, improving interference resistance, and the like.

[0008] Thus, the number of light curtains adopting the optical synchronization system increases.

[0009] The operating indicator light of the light curtain is generally provided in both the light transmitter and the light receiver. In this case, it is necessary to lock the operating indicator light's state in both the transmitter and the receiver. For example, for (1) the power supply being on or off, and (3) the fault condition described above, the states of the transmitter and receiver may differ. On the other hand, for (2) the OSSD output being on or off—that is, the light receiving state and the light shielding state—the operating indicator light must be in the same state in both the transmitter and the receiver.

[0010] Accordingly, to improve the visibility of the operating indicator light, it is desirable to lock and indicate its status in both the light transmitter and the light receiver. To implement such locking and indication of the operating indicator light, it is necessary to inform the light transmitter about the on or off state of the OSSD output from the light receiver.

[0011] For example, as disclosed in Japanese patent application 2002-124169, in a light curtain that adopts a wired synchronization system, a light transmitter and a light receiver are originally connected via a cable. Therefore, it is sufficient to add a communication line for locking and display control within the cable.

[0012] On the other hand, with a light curtain that uses an optical synchronization system, there is no communication path from the light receiver to the light transmitter. Therefore, it is necessary to run separate communication lines for interlocking and indicator control between the light transmitter and the light receiver in order to lock and display the operating indicator light in both devices. This means that wiring work between the light transmitter and the light receiver is required, and the advantage of the optical synchronization system is diminished. BRIEF SUMMARY OF THE INVENTION

[0013] In view of the problems mentioned above, one objective of the invention is to improve the wiring efficiency in a case where an operating indicator light is provided in a light curtain of an optical synchronization system.

[0014] A light curtain according to the invention comprises, for example, a light transmitter comprising a plurality of first light projection elements, a light receiver arranged opposite the light transmitter comprising a plurality of first light receiving elements configured to receive light beams projected by the plurality of first light projection elements, a synchronization unit configured to synchronize a light projection time of the light transmitter and a light reception time of the light receiver by optical communication, and a safety signal generated based on whether each of a plurality of optical axes formed between the light transmitter and the light receiver is in a light-shielding state is emitted to an outside world.The light curtain comprises a first operating indicator lamp provided in the light transmitter and configured to indicate an operating state of the light curtain, a second operating indicator lamp provided in the light receiver and configured to indicate the operating state of the light curtain, at least one set of optical elements provided in each of the light transmitter and the light receiver and configured to lock and indicate the first operating indicator lamp and the second operating indicator lamp, and a control circuit configured to lock and indicate the first operating indicator lamp and the second operating indicator lamp using the at least one set of optical elements.

[0015] Note that other features, elements, steps, benefits and properties will become clearer from the following detailed description and accompanying drawings.

[0016] According to the invention, dedicated wiring for interlocking the operating indicator lights, which are provided in both the light transmitter and the light receiver, becomes unnecessary. Accordingly, wiring efficiency can be improved in a case where the operating indicator light is located in the light curtain of the optical synchronization system. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a diagram illustrating a schematic configuration of a light curtain; Fig. Figure 2 is a perspective view illustrating the overall configuration of a light source; Fig. Figure 3 is a front view illustrating the overall configuration of the light emitter; Fig. Figure 4 is a perspective view illustrating one end of the light source; Fig. 5 is a functional block diagram of the light curtain; Fig. Figure 6 is a diagram illustrating a first embodiment of the light emitter; Fig. 7 is a diagram illustrating an example arrangement of indicator lamp sources according to the first embodiment; Fig. Figure 8 is a diagram illustrating a relationship between a light emission color and an operating mode; Fig. 9 is a diagram illustrating an arrangement example of indicator lamp sources according to a second embodiment; Fig. 10 is a diagram illustrating a display pattern example according to the second embodiment; Fig. 11 is a diagram illustrating an arrangement example and a display pattern example of indicator lamp sources according to a third embodiment; Fig. 12 is a diagram illustrating an arrangement example and a display pattern example of indicator lamp sources according to a fourth embodiment; Fig. Figure 13 is a diagram illustrating a relationship between an average amount of light received and a display pattern; Fig. Figure 14 is a diagram illustrating a relationship between a minimum amount of light received and a display pattern; Fig. 15 is a diagram illustrating an illuminated image (first example) of a light curtain; Fig. Figure 16 is a diagram illustrating an illuminated image (second example) of a light curtain; Fig. Figure 17 is a functional block diagram of a light curtain with a display pattern control function; Fig. 18 is a diagram illustrating a processing flow of the display pattern control; Fig. 19 is a diagram illustrating a configuration example of a light curtain according to a fifth embodiment; Fig. Figure 20 is a schematic view illustrating an example of optical axis formation; Fig. 21 is a diagram illustrating a processing flow of the locking and display control; Fig. Figure 22 is a top view illustrating a configuration example of a light receiver; Fig. Figure 23 is a perspective view illustrating a configuration example of the light receiver; Fig. Figure 24 is a diagram illustrating an example of mutual light interference under a multitude of light curtains; Fig. Figure 25 is a diagram illustrating an example of an optical axis drive control; and Fig. Figure 26 is a longitudinal section view illustrating an example of a light receiver including a light leakage suppression mechanism. DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS <lichtvorhang>

[0017] Fig. Figure 1 is a diagram illustrating a schematic configuration of a light curtain. The light curtain 1 of the present configuration example is an aspect of a multi-optical-axis photoelectric sensor and generally comprises a pair of a light transmitter 100 and a light receiver 200.

[0018] The light curtain 1 detects a person or object depending on whether at least one of a plurality of optical axes (six optical axes Oax1 to Oax6 in this drawing), which are spaced apart between the parallel light transmitter 100 and the light receiver 200, is blocked. For example, the light curtain 1 is provided at an entrance or the like of a hazardous area where a hazard such as a press is located and can be used as a safety device to detect the intrusion or presence of a worker.

[0019] The light transmitter 100 and the light receiver 200 each comprise extended (up to 2 m or more) housings 110 and 210 and associated cables 120 and 220.

[0020] The housing 110 comprises a hollow metal housing 111 extending in a longitudinal direction and hollow end caps 112 and 113 (corresponding to end pieces), each connected to both ends of the metal housing 111. Similarly, the housing 210 comprises a hollow metal housing 211 extending in a longitudinal direction and hollow end caps 212 and 213 (corresponding to end pieces), each connected to both ends of the metal housing 211. In the present embodiment, the longitudinal direction is a direction that is substantially parallel to a direction in which the plurality of optical axes formed between the light emitter 100 and the light receiver 200 are spaced apart.

[0021] As described above, if the metal housings 111 and 211 are assumed to have high stiffness as the housings for housings 110 and 210, the extended housings 110 and 210 are less likely to deform. Accordingly, adjusting the arrangement (for example, adjusting the angle to arrange both housings parallel) of the light transmitter 100 and the light receiver 200 becomes relatively simple. Note that, for example, a cost-effective and lightweight extruded aluminum product can be used as the metal housings 111 and 211. In this case, the metal housings 111 and 211 all have the same cross-section, regardless of where the metal housings are cut in an extrusion direction (= longitudinal direction).

[0022] Each of the end caps 112, 113, 212, and 213 can be formed by injection molding using a resin material or by die casting using a metal material such as zinc. Note that interfaces with cables 120 and 220 can be mounted on the underside of end caps 113 and 213 in this drawing. Therefore, end caps 113 and 213 can be larger than end caps 112 and 212 in this drawing. <lichtsender>

[0023] Fig. 2 and Fig. Figure 3 is a perspective view or a front view illustrating the overall configuration of the light transmitter 100. Furthermore, Fig. 4 a perspective view illustrating one end of light transmitter 100.

[0024] As described above, the light transmitter 100 comprises the housing 110 and the cable 120. Additionally, the housing 110 includes the metal housing 111 and the end caps 112 and 113. Furthermore, the light transmitter 100 includes a front cover 130, indicator lamps 140, and bumper 150.

[0025] The front cover 130 is an extended translucent plate attached to cover a front opening (detection window) of the housing 110. Light projection elements 161 to 166 are arranged at equal intervals along a longitudinal direction in the front opening of the housing 110 to form the plurality of optical axes Oax1 to Oax6. That is, the front cover 130 is attached to the housing 110 such that it intersects the plurality of optical axes Oax1 to Oax6. The front cover 130 can be an extruded translucent resin plate (acrylic plate or the like) or a glass plate.The translucent properties of the element used as the front cover 130 in the present embodiment relate to translucency such that light rays from the light projection elements 161 to 166, which form the plurality of optical axes Oax1 to Oax6, are not excessively scattered from the optical axes and are received by the light receiving elements 261 to 266, to be described later, with a certain amount of light or more. As described above, a worker can visually detect the light projection elements 161 to 166 through the front cover 130, since the translucent element is used for the front cover 130.

[0026] Note that the light projection element (the light projection element 166 in Fig. 3) which corresponds to at least one optical axis among the plurality of optical axes Oax1 to Oax6, can be arranged in the end cap 113. That is, the light projection elements 161 to 166 can be arranged at equal intervals in the longitudinal direction over the entire area from one end to the other of the light transmitter 100. In addition, the cable 120 can originate from a rear (or side) surface of the end cap 113 instead of from a bottom surface of the end cap 113. With such a configuration, the light transmitter 100 can be installed close to an installation surface (floor surface or the like). Accordingly, a dead-space-free state can be achieved.

[0027] The indicator lamps 140 are controlled to be switched on or off with a light emission color that corresponds, for example, to an operating state of the light curtain 1 (an optical axis detection state, a self-diagnostic result, or the like) or to a work instruction regarding the insertion and removal of an object. That is, the indicator lamp 140 functions as an operating indicator light or as a work instruction light. Accordingly, the worker can visually recognize the operating state or work instruction of the light curtain 1 by looking at the indicator lamps 140 of the light curtain 1.

[0028] In particular, the indicator lamps 140 are arranged outwards from an outer surface of at least one of the front cover 130 and the housing 110 along a longitudinal direction or formed in series with the front cover 130 (details of the structure are described later). Referring to this drawing, the indicator lamps 140 are provided on both sides of the front cover 130. With the indicator lamps 140 arranged or formed in this way, it is possible to provide a clearly visible display without compromising the rigidity of the housing 110. More precisely, the indicator lamp 140 is an elongated extruded product and is arranged such that its longitudinal direction runs along the longitudinal direction of the housing 110.Note that the indicator lamps 140 can be arranged along the longitudinal direction of the housing 110, and the manufacturing method for this is not limited to extrusion, and the shape of the indicator lamp 140 need not be the elongated shape. For example, a variety of elements functioning as indicator lamps 140 can be arranged along the longitudinal direction of the housing 110.

[0029] Furthermore, the indicator lamp 140 is a light-diffusing element that scatters light incident from an indicator lamp source 170 (not shown), which is housed inside the casing 110, in various directions. More precisely, the indicator lamp 140 contains a light-diffusing element that scatters light in different directions. In the configuration where the light-diffusing element, as the indicator lamp 140, contains the light-diffusing element, a clearly visible display can be achieved even if the number of indicator lamp light sources 170 is small relative to the surface area of ​​the indicator lamp 140, since the indicator lamp 140 can be illuminated relatively uniformly. In the present embodiment, the indicator lamp 140 is milky white because it is made of a transparent resin to which fine particles have been added.In a case where a base resin is not transparent but has a specific color, the specific color is mixed with a milky white resin. In a case where the indicator lamp 140 is made of a milky white resin (silicone or the like), in addition to the configuration in which the light-diffusing element contains the light-diffusing body, it is possible to achieve a relatively uniform illumination of the indicator lamp 140. The light-diffusing element, in the case of the indicator lamp 140, can be an element that scatters the light from the indicator lamp source 170 in such a way that the light can be visually detected from more directions, or an element that scatters the light from the indicator lamp source 170 to such an extent that it is difficult to visually discern a contour of the indicator lamp source 170 from the outside of the indicator lamp 140.For example, a light-diffusing element with a machined surface to diffuse the light from the indicator lamp source 170 can be arranged as an indicator lamp 140. For example, embossing is a known surface treatment for diffusing light. With the configuration in which the light-diffusing element with the machined surface is arranged as an indicator lamp 140, it is easy to manufacture such an element in a case where an area in which light is diffused relatively easily and an area in which light is diffused relatively less easily are provided within the element.

[0030] The bumpers 150 protrude outwards from an area of ​​the outer surface of the front cover 130 which intersects the plurality of optical axes Oax1 to Oax6, and are arranged along the longitudinal direction of the housing 110 (details of a structure will be described later).

[0031] Referring to this drawing, a pair of bumpers 150 are formed such that they project from both sides of the front cover 130. That is, the front cover 130 is arranged in a narrow valley that is wedged between the pair of bumpers 150 (double bumpers proposed by the applicant of the present application), which are positioned on both sides of it and project forward. Thus, even if the object collides with a front face of the light emitter 100, the impact is absorbed by the bumpers 150. Accordingly, the front cover 130 is less likely to be damaged. Note that the bumper 150 can be made of a hard material such as metal.

[0032] Furthermore, a configuration of the light receiver 200 is essentially similar to a configuration of the light transmitter 100. Accordingly, the description of the Fig. Sections 2 to 4 describe the configuration of the light receiver 200 by reading the light transmitter 100 and the light projection elements 161 to 166 in the same way as the light receiver 200 and the light receiving elements 261 to 266, respectively, and by replacing the reference numerals in other 100s series with corresponding reference numerals in 200s series. The same applies to the following description. <funktionsblock>

[0033] Fig. Figure 5 is a functional block diagram of the light curtain 1. In the light curtain 1 of the present configuration example, the light transmitter 100 comprises the indicator lamps 140, the light projection elements 161 to 166, the indicator lamp source 170, a control circuit 181 and a communication circuit 182.

[0034] The light projection elements 161 to 166 are arranged at equal intervals with a predetermined spacing along the longitudinal direction of the light source 100. The light projection elements 161 to 166 sequentially project a plurality of light beams to form the plurality of optical axes Oax1 to Oax6 to the light receiver 200 (in particular to the light receiving elements 261 to 266) in a time-division multiplexing procedure based on a light projection control signal input by the control circuit 181. Note that the light projection elements 161 to 166 can, for example, be light-emitting diodes emitting infrared light beams.

[0035] The indicator lamp source 170 supplies light for display to the indicator lamps 140 based on a display control signal input from the control circuit 181. The indicator lamp source 170 can be switched between a variety of light emission colors (for example, red, green, and orange), in accordance with the operating state of the light curtain 1, the work instructions, or the like.

[0036] Note that the indicator lamp source 170 can be switched on in pulses at a time offset from a light projection or light reception time of each of the plurality of optical axes Oax1 to Oax6. According to such switch-on or switch-off control, interference with the detection of the optical axis by the indicator lamp source 170 can be suppressed.

[0037] The indicator lamp 140 scatters light incident from the indicator lamp source 170 in various directions. The worker can visually determine the operating status of the light curtain 1, the work instructions, or the like by looking at the indicator lamps 140.

[0038] In response to an instruction from the light receiver 200, the control circuit 181 generates the light projection control signal to sequentially drive the light projection elements 161 to 166 using time-division multiplexing. The control circuit 181 also generates the display control signal to switch the display lamp source 170 on or off in each light emission color. Furthermore, the control circuit 181 exchanges various types of information with the communication circuit 182.

[0039] The communication circuit 182 performs wired or wireless communication with the light receiver 200 (in particular with the communication circuit 282). For example, the communication circuit 182 receives input information regarding the operating state (an optical axis detection state, a self-diagnostic result, and the like) of the light curtain 1 from the light receiver 200 and transmits the information to the control circuit 181.

[0040] On the other hand, the light receiver 200 comprises an indicator lamp 240, light receiving elements 261 to 266, an indicator lamp source 270, a control circuit 281, a communication circuit 282, an output circuit 283 and an input circuit 284.

[0041] The light receiving elements 261 to 266 are arranged at equal intervals along the longitudinal direction of the light receiver 200, with the same spacing as the light projection elements 161 to 166. The light receiving elements 261 to 266 sequentially receive a plurality of light beams to form the plurality of optical axes Oax1 to Oax6 in a time-division multiplexing procedure based on a light receiving control signal input by the control circuit 281. Note that the light receiving elements 261 to 266 can be, for example, photodiodes or phototransistors that output electrical signals corresponding to a received amount of infrared light.

[0042] The indicator lamp source 270 supplies light for the display to the indicator lamp 240 based on a display control signal input from the control circuit 281. Similar to the indicator lamp source 170, the indicator lamp source 270 can be switched between a variety of light emission colors (for example, red, green, and orange), in accordance with the operating state of the light curtain 1, the work instructions, or the like.

[0043] Note that the indicator lamp source 270 can be switched on in pulses at a time offset from the light projection or light reception time of each of the plurality of optical axes Oax1 to Oax6. According to such switch-on or switch-off control, interference with the detection of the optical axis by the indicator lamp source 270 can be suppressed.

[0044] Furthermore, a case is considered in which the indicator lamp source 270 is continuously switched on. In this case, it is desirable to provide a saturation prevention circuit (= a subtraction circuit for a DC component) so that the electrical signals output by the light receiving elements 261 to 266 are not saturated, even though DC light from the indicator lamp source 270 is received by the light receiving elements 261 to 266.

[0045] The indicator lamp 240 disperses the light incident from the indicator lamp source 270 in various directions. The worker can visually recognize the operating status of the light curtain 1, the work instructions, or the like by looking at the indicator lamp 240.

[0046] Furthermore, since the indicator lamps 140 and 240 are each provided on both the light transmitter 100 and the light receiver 200, a clearly visible display can be carried out.

[0047] Control circuit 281 generates the light reception control signal to sequentially activate the light receiving elements 261 to 266 in a time-division multiplexing procedure, synchronized with the activation time of each of the light projection elements 161 to 166. Furthermore, control circuit 281 generates the display control signal to switch the display lamp source 270 on or off in each light emission color. Control circuit 281 also exchanges various types of information with communication circuit 282, output circuit 283, and input circuit 284.

[0048] Furthermore, the control circuit 281 monitors the light incidence or light shielding state of each of the plurality of optical axes Oax1 to Oax6. For example, the control circuit 281 can output an operating permit signal (ON signal) when all of the plurality of optical axes Oax1 to Oax6 are in the light incidence state. Conversely, the control circuit 281 can output an operating denial signal (OFF signal) when at least one of the plurality of optical axes Oax1 to Oax6 is in the light shielding state.

[0049] Furthermore, the control circuit 281 can have a self-diagnostic function to monitor whether the light incidence or light shielding state of each of the plurality of optical axes Oax1 to Oax6 is being monitored correctly. Note that, as a self-diagnostic method, for example, the control circuit 281 and the output circuit 283 (for example, an output signal switching device [OSSD] output) can be multiplexed, and the agreement or mismatch of the multiplexed signals can be determined.

[0050] For example, if the multiplexed signals match, an OK diagnosis (a diagnostic result indicating that the condition can be monitored correctly) is generated. Conversely, if the multiplexed signals do not match, an NG diagnosis (a diagnostic result indicating that the condition cannot be monitored correctly) is generated. Note that in a case where the NG diagnosis is generated, the disable signal (OFF signal) can be output regardless of the light incidence condition of each of the multiple optical axes Oax1 to Oax6.

[0051] Note that information that can be used for safety control is safety information, and general information that cannot be used for safety control is non-safety information. For example, the OSSD output is a piece of safety information. The signal used to turn on or off each of the indicator lamp sources 170 and 270 can be a signal indicating safety information or a signal indicating non-safety information.

[0052] The communication circuit 282 performs wired or wireless communication with the light transmitter 100 (in particular with the communication circuit 182). For example, the communication circuit 282 receives an input of information regarding the operating state (an optical axis detection state, a self-diagnostic result, and the like) of the light curtain 1 from the control circuit 281 and transmits the information to the light transmitter 100.

[0053] Output circuit 283 performs wired or wireless communication with an external device (for example, a safety controller). For example, output circuit 283 receives an input regarding the operating status (an optical axis detection state, a self-diagnostic result, or the like) of the light curtain 1 from the control circuit 281 and transmits the information to an external device.

[0054] The input circuit 284 performs wired or wireless communication with an external device (for example, a safety controller). For example, the input circuit 284 receives an input of a work instruction regarding the insertion and removal of an object from an external device and transmits the work instruction to the control circuit 281. <Erste Ausführungsform>

[0055] Fig. Figure 6 is a diagram (= a schematic sectional view when a metal housing 111 of a light emitter 100 is cut at any position in the longitudinal direction) illustrating a first embodiment of the light emitter 100. The light emitter 100 of the present embodiment comprises a housing 110 (only one metal housing 111 is shown in this drawing), a front cover 130, indicator lamps 140, a bumper 150, a control lamp light source 170, a substrate 190, and a light shielding plate 191.

[0056] The metal housing 111 is an extruded product extending in the longitudinal direction of the light emitter 100. Referring to this drawing, the metal housing 111 includes a body 111a, a pair of first projecting strips 111b, and a pair of second projecting strips 111c.

[0057] Body 111a is a hollow body with a U-shaped cross-section and an opening on one top surface (= one front surface of the light source 100). The indicator lamp source 170, the substrate 190, and the light shielding plate 191 are housed within the interior of body 111a.

[0058] The pair of first projecting strips 111b protrudes from the inner surfaces of the left and right side walls of the body 111a toward an inner side of the opening. That is, the pair of first projecting strips 111b are arranged such that they face each other at a predetermined distance and clamp an optical axis intersection region X (= a region that intersects a plurality of optical axes Oax1 to Oax6). Note that the pair of first projecting strips 111b act as cover fixing elements to support the front cover 130. As described above, a translucent element is used for the front cover 130, provided that the translucent element is provided at least within the optical axis intersection region X and does not interfere with the optical axes Oax1 to Oax6.For example, in the present embodiment, a part that comes into contact with the pair of first projecting strips 111b need not necessarily have light-transmitting properties.

[0059] The pair of second projecting strips 111c extends further upwards in the drawing from the upper ends of the left and right side walls of the body 111a. Furthermore, each of the pair of second projecting strips 111c has a distal end that is bent towards the inside of the opening. Note that the pair of second projecting strips 111c functions as the bumpers 150 to protect the front cover 130. That is, in the present embodiment, the bumpers 150 described above are formed from the metal housing 111. Accordingly, the strength of the light transmitter 100 can be improved.

[0060] The front cover 130 is supported (suspended) at both ends by the pair of first projecting strips 111b. The front cover 130 allows light rays forming the plurality of optical axes Oax1 to Oax6 to pass through the optical axis intersection area X. Processing to improve liquid resistance is carried out between the front cover 130 and the pair of first projecting strips 111b (see thick line α). For example, processing involves applying a gasket and bonding with a liquid-resistant adhesive. As described later, since the adhesive properties between the front cover 130 and the first projecting strips 111b are improved by the indicator lamps 140, the liquid resistance is further enhanced.

[0061] The indicator lamps 140 are arranged on both sides of the front cover 130, adjacent to the bumpers 150. Referring to this drawing, the indicator lamps 140 are arranged along the longitudinal direction of the light source 100 in areas that are clamped between the first projecting strips 111b and the distal ends (curved sections) of the second projecting strips 111c, that is, in areas that are clamped between the bumpers 150 and the front cover 130.

[0062] Note that the indicator lamp 140 scatters the light entering from the indicator lamp source 170 via the front cover 130 in various directions. For example, the indicator lamp 140 may have a tapered shape to refract and scatter the light entering from the indicator lamp source 170 towards the inside of the opening.

[0063] With the indicator lamps 140 arranged in this way, it is easy to see even from one side of the light source 100. Accordingly, with the small-format (small-caliber) light curtain 1, which uses the metal housing 111, it is possible to implement a highly visible display without compromising the rigidity of the housing 110. In particular, in a case where the pair of bumpers 150 are designed to protrude from both sides of the front cover 130, the effect of the aforementioned arrangement on improved visibility can be more noticeable.

[0064] Furthermore, in the light transmitter 100 of the present embodiment, the indicator lamps 140 also function as pressure elements for pressing and securing the front cover 130 downwards (i.e., in one direction towards the first projecting strips 111b). Accordingly, since the adhesive properties between the front cover 130 and the first projecting strip 111b are improved, the liquid resistance can be enhanced by preventing liquid from penetrating the interior of the metal housing 111. Note that it is desirable for the indicator lamps 140 to possess suitable elasticity so that they can function as pressure elements.

[0065] The indicator lamp source 170 is mounted on a main surface (= a surface facing the front cover 130) of the substrate 190. The indicator lamp source 170 provides light for display in the direction of the indicator lamps 140 via the front cover 130. Referring to this drawing, the light emitted by the indicator lamp source 170 passes between the pair of first projecting strips 111b without being shielded by the pair of first projecting strips 111b and is delivered to the indicator lamps 140 via the front cover 130.

[0066] Note that the number of indicator lamp sources 170 is not limited. For example, several indicator lamp sources 170 can be arranged intermittently or in series along the longitudinal direction of the light source 100.

[0067] Furthermore, the indicator lamp source 170 can include a lens for controlling the direction of the emitted light. For example, a lens can be provided that is optically designed to reduce the propagation angle of the light in a left-right direction and increase the propagation angle of the light in a depth direction. With such a lens, it is possible to reduce the number of indicator lamp light sources 170 while suppressing interference along the multiple optical axes Oax1 to Oax6.

[0068] Note that one type of lens can be a point-symmetric lens (single-lens arrangement) or a cylindrical lens (row arrangement by extrusion product).

[0069] The light-shielding plate 191 is arranged between the indicator lamp source 170 and the optical axis intersection area X. Accordingly, since the light from the indicator lamp source 170 is shielded in the direction of the optical axis intersection area X, it is less likely that the light emitted by the indicator lamp source 170 will interfere with the plurality of optical axes Oax1 to Oax6.

[0070] Furthermore, a case is considered in which the optical axes Oax1 to Oax6 are formed by infrared light and visible light (red light, green light, orange light, or the like) is emitted by the indicator lamp source 170. In this case, a filter that transmits infrared light and blocks visible light can be provided in the light receiver 200. In particular, in a case in which the indicator lamps 240 are provided in the light receiver 200, a filter that transmits infrared light and blocks visible light can be arranged such that it does not block the display of the indicator lamps 240. Filters can be provided in the light receiving elements 261 to 266, or a filter can be provided in a lens that directs light to the light receiving elements 261 to 266.

[0071] Fig. Figure 7 is a diagram illustrating an example arrangement of the indicator lamp source 170 according to the first embodiment. As shown in this drawing, the light projection elements 161 to 166 can be arranged at equal intervals along a longitudinal direction of the substrate 190 in a central region 190a of the substrate 190. Conversely, the indicator lamp source 170 can be arranged at equal intervals along the longitudinal direction of the substrate 190 in an end region 190b of the substrate 190.

[0072] In particular, the light projection elements 161 to 166 and the control lamp light sources 170 can be arranged such that their positions are offset (staggered) from one another along the longitudinal direction of the substrate 190. According to such an arrangement, mutual interference between the light projection elements 161 to 166 and the control lamp light sources 170 is suppressed.

[0073] Note that the number and arrangement of the indicator lamp sources 170 are not limited to the arrangement example in this drawing. For example, the number of indicator lamp sources 170 can be reduced so that the light beams supplied to the indicator lamps 140 exhibit a certain degree of unevenness. <anzeigeinhalt>

[0074] Fig. Figure 8 is a diagram illustrating the relationship between the light emission color of indicator lamp 140 and an operating mode. As shown in this diagram, indicator lamp 140 can be switched to any mode, either the operating indicator lamp mode or the work instruction lamp mode. For example, a control signal for switching the operating mode of indicator lamp 140 could be a 2-bit (four-value) digital signal input into input circuit 284.

[0075] First, a case is described in which the indicator lamp 140 is set to the operating indicator lamp mode. When the operating indicator lamp mode is set, the indicator lamp 140 is controlled to be switched on or off with a light emission color that corresponds to the operating state of the light curtain 1.

[0076] Referring to this drawing, for example, when the light curtain 1 is in a normal state (for example, a state in which all of the plurality of optical axes Oax1 to Oax6 are not shielded), the indicator lamp 140 is illuminated green. Conversely, when the light curtain 1 is in a fault state (for example, an emergency stop state in which at least one of the plurality of optical axes Oax1 to Oax6 is shielded), the indicator lamp 140 is illuminated red. Furthermore, the indicator lamp 140 flashes red when the light curtain 1 is in an alarm notification state (for example, an NG diagnostic state triggered by a self-diagnostic function).

[0077] Next, a case is described in which the indicator lamp 140 is set to the work instruction lamp mode. When the work instruction lamp mode is set, the indicator lamp 140 is controlled to be turned on or off with a light emission color that corresponds to the work instruction signal received by the input circuit 284.

[0078] Referring to this drawing, for example, when the work instruction signal indicates a "work permitted" state, indicator lamp 140 will illuminate green. Conversely, when the work instruction signal indicates a "work prohibited" state, indicator lamp 140 will illuminate red. Additionally, when the work instruction signal indicates "self-diagnosis," indicator lamp 140 will flash red. Note that in work instruction lamp mode, indicator lamp 140 may illuminate orange. The method for using an illuminated state may vary depending on the user.

[0079] Furthermore, in a case where the light curtain 1 is used in an environment where light emission from the indicator lamp 140 is not desirable, the indicator lamp 140 can be switched off permanently. <Betrachtung zur Reduzierung der Lichtempfangsmenge auf der optischen Achse>

[0080] As described above, the light curtain comprises two parts, the light source and the light receiver, and the multiple light-projecting and light-receiving elements are arranged along a single axis. When the light curtain is used, the light source and light receiver are positioned parallel to each other, and an angle is adjusted so that a sufficient amount of light passes through all elements. The greater the distance between the light source and the light receiver, the more difficult it is to determine if the alignment is correct, and the more difficult it is to see the display. Therefore, adjusting the angle is challenging.

[0081] The light curtain can be used in harsh environments, such as those exposed to dirt or impacts. Therefore, a bumper-shaped guard is incorporated to protect the front cover of the detection unit. However, preventing dirt from accumulating on the front cover is challenging. If dirt accumulates and the light-receiving elements cannot receive sufficient light, the optical axis is in a light-shielding state, and the device's activation may be blocked by the light curtain's safety output. Therefore, regular maintenance to clean the front cover's glass surface is necessary to prevent any impact on the optical axis's detection performance.

[0082] In environments where dirt accumulates, the light curtain must be installed to ensure a sufficient light reception level on the optical axis, with a safety margin to compensate for a decrease in light reception due to dirt (i.e., the light reception level of each optical axis, which serves as the criterion for determining whether the optical axis is in the light-shielding state or not). Furthermore, maintenance is required before the optical axis enters the light-shielding state by verifying any decrease in light reception level over time.

[0083] Furthermore, it is difficult to notice a decrease in the amount of light received on the optical axis during the operation of the light curtain, unless the small indication described above is taken into account and confirmed.

[0084] On the other hand, large-format indicator lamps 140 and 240 are provided in the light curtain 1 described so far in the present specification, so that an activation state of the light curtain 1 can be easily visually recognized, while at the same time both size reduction and high visibility are achieved.

[0085] In view of the above considerations, a novel embodiment is proposed below in which a display linked to the amount of light received on the optical axis can be carried out with high visibility by the indicator lamps 140 and 240. <Zweite Ausführungsform>

[0086] Fig. Figure 9 is a diagram illustrating an example arrangement of an indicator lamp source according to a second embodiment. In the present embodiment, several (two in this drawing) substrates 190 with identical structure are cascaded along a longitudinal direction. With such a configuration, a light curtain 1 can be easily extended by simply increasing the number of cascades of the substrates 190.

[0087] In this drawing, which illustrates a light transmitter 100, light projection elements 161 to 166 can be arranged at equal intervals along the longitudinal direction of the substrate 190 in a central area 190a of the substrate 190, similar to the one described above. Fig. 7. Referring to this drawing, the light projection elements 161 to 163 are arranged on the substrate 190 on the right side of the drawing in a sequence shown, from right to left. Conversely, on the substrate 190 on the left side of the drawing, the light projection elements 164 to 166 are arranged in a sequence shown, from right to left. Note that if a configuration of a light receiver 200 is understood, each of the light projection elements 161 to 166 can be read as light receiving elements 261 to 266.

[0088] On the other hand, the indicator lamp light sources 170 can be arranged at equal intervals along the longitudinal direction of the substrate 190 in an end region 190b of the substrate 190. In particular, the indicator lamp light sources 170 can be distinguished as indicator lamp light sources 170a, 170b, and 170c depending on a difference in each control system. With reference to this drawing, the indicator lamp light sources 170a, 170b, and 170c are arranged on two substrates 190 in a sequence shown from left to right of the drawing. Note that, although not shown in this drawing, the light curtain 1 includes an OSSD indicator lamp whose display aspect changes according to an OSSD output, separate from the indicator lamp light source 170. Thus, the display aspect of the indicator lamp light source 170 changes to indicate light receiving states of the light receiving elements 261 to 266.

[0089] As described above, the light projection elements 161 to 163 (or 164 to 166) and the indicator lamp sources 170a, 170b and 170c are arranged as a unit on the common substrate 190. In particular, the indicator lamp sources 170a, 170b and 170c are unified as a set of three light sources.

[0090] Note that, as a modification, the light projection elements 161 to 163 (or 164 to 166) and the indicator lamp sources 170a, 170b and 170c can be separate units. That is, a unit in which the light projection elements 161 to 163 (or 164 to 166) are arranged and a unit in which the indicator lamp sources 170a, 170b and 170c are arranged can be independent of each other.

[0091] Fig. Figure 10 is a diagram illustrating a display pattern example according to the second embodiment. The upper part of this drawing shows an "on state." In this "on state," the indicator lamp sources 170a are switched on, and both the indicator lamp sources 170b and 170c are switched off. Accordingly, a display pattern is obtained in which "one on, two off" is repeated from the left to the right side of the drawing.

[0092] In the central part of this drawing, an "off-on state" is depicted. In this "off-on state," both indicator lamp sources 170a and 170b are switched on, and indicator lamp source 170c is switched off. Accordingly, a display pattern is obtained in which "two on, one off" is repeated from one left side to one right side of the drawing.

[0093] The lower part of this drawing shows an "ABC-on state". In this "ABC-on state", all indicator lamp sources 170a, 170b and 170c are switched on.

[0094] As described above, in a display pattern example according to the present embodiment, the indicator lamp sources 170a, 170b, and 170c are switched on at appropriately intermittent intervals. Accordingly, the display pattern is switched to one of the three patterns mentioned above according to the amount of light received on the optical axis, and thus the amount of light received on the optical axis can be distinguished only by observing the large-format indicator lamps 140 and 240. As a result, the light curtain 1 is provided, which can be easily adjusted at the time of initial setup and exhibits high maintainability. <Dritte Ausführungsform>

[0095] Fig. Figure 11 is a diagram illustrating an arrangement example and a display pattern example of indicator lamp sources according to a third embodiment. In the present embodiment, two indicator lamp sources 170a, two indicator lamp sources 170b, and two indicator lamp sources 170c are arranged as a single unit on a common substrate 190. That is, the indicator lamp sources 170a, 170b, and 170c are unified as a set of six light sources.

[0096] Referring to this drawing, two indicator lamp sources 170a, two indicator lamp sources 170b and two indicator lamp sources 170c are arranged on the substrate 190 in the sequence shown from a left side to a right side of the drawing.

[0097] The upper part of this drawing depicts an "on state." In this "on state," indicator lamp sources 170a are switched on, and both indicator lamp sources 170b and 170c are switched off. Accordingly, a display pattern is obtained in which "two on, four off" is repeated from the left to the right side of the drawing.

[0098] In the central part of this drawing, an "off-on state" is depicted. In this "off-on state," both indicator lamp sources 170a and 170b are switched on, and indicator lamp sources 170c are switched off. Accordingly, a display pattern is obtained in which "four on, two off" repeats from the left to the right side of the paper surface.

[0099] The lower part of this drawing shows an "ABC-on state". In this "ABC-on state", all indicator lamp sources 170a, 170b and 170c are switched on.

[0100] Note that in the second embodiment described above ( Fig. 10) the number of indicator lamp sources 170a, 170b and 170c in a non-switched-on state (off state) is increased or decreased by one for each display pattern, such as 2, 1 and 0.

[0101] On the other hand, in the arrangement example of the indicator lamp sources and the display pattern example according to the present embodiment, the number of indicator lamp sources 170a, 170b and 170c in the off state is increased or decreased by two, such as 4, 2 and 0 for each display pattern. Accordingly, in comparison to the second embodiment described above ( Fig. 10) A large difference in distance exists between the light sources that are to be switched on intermittently. As a result, the switching of the display pattern (and the change in the amount of light received on the optical axis) is easily detected by the light diffuser. <Vierte Ausführungsform>

[0102] Fig. Figure 12 is a diagram illustrating an arrangement example and a display pattern example of indicator lamp sources according to a fourth embodiment. Similar to the second embodiment described above ( Fig. 10) In the present embodiment, indicator lamp sources 170a, 170b and 170c are unified as a set of three. However, the arrangement order of the indicator lamp sources 170a, 170b and 170c on each substrate 190 differs.

[0103] Referring to this drawing, the indicator lamp sources 170a, 170b, and 170c are arranged on the substrate 190 on the left side of the drawing in the sequence shown, from left to right. On the other side, the indicator lamp sources 170a, 170b, and 170c are arranged on the substrate 190 on the right side of this drawing in the sequence shown, from right to left.

[0104] The upper part of this drawing depicts an "on state." In this "on state," indicator lamp sources 170a are switched on, and both indicator lamp sources 170b and 170c are switched off. Accordingly, a display pattern is obtained in which "one on, four off, one on" is repeated from the left to the right side of the drawing.

[0105] A lower part of this drawing depicts a "BC-on state". In this "BC-on state", indicator lamp source 170a is switched on, and both indicator lamp light sources 170b and 170c are switched off. Accordingly, a display pattern is obtained in which "one off, four on, one off" is repeated from the left to the right side of the drawing.

[0106] As described above, in the arrangement example and the display pattern example of the indicator lamp sources according to the present embodiment, the number of indicator lamp sources 170a, 170b, and 170c in the off state is increased or decreased by two, such as 4, 2, and 0 for each display pattern, while maintaining a set of three units. Accordingly, similar to the third embodiment described above ( Fig. 11), the switching of the display pattern (and the change in the amount of light received on the optical axis) is easily detected. <Beziehung zwischen Lichtempfangsmenge auf der optischen Achse und Anzeigemuster>

[0107] Fig. Figure 13 is a diagram illustrating the relationship between the amount of light received on the optical axis (average light received) and the display pattern. The amount of light received on the optical axis is converted by an analog-to-digital converter and compared to a threshold value. An average value (= average light received) of the light received values ​​on the optical axes can be used as a criterion for determining the display pattern.

[0108] First, an ON state of the OSSD indicates a state where the condition that "the light reception levels of all optical axes are at least a first threshold" is met for the light-receiving elements 261 to 266, and the OSSD output is ON. For simplicity, in the present embodiment, a state in which the light-receiving elements 261 to 266 meet the condition and the OSSD output can be switched on is defined as the determining ON state, and the determining ON state is a state in which "the light reception levels of all optical axes are at least the first threshold." The first threshold is identical to a threshold for determining whether each individual optical axis is in the light-shielding state.Therefore, the average light reception in this state is high to a certain extent and cannot be low enough to be considered "complete light blocking". That is, since the light reception values ​​of all optical axes are at or above the first threshold, the average light reception cannot fall below the first threshold.

[0109] Accordingly, the "OFF" indication, when the average light reception falls below the first threshold, can be understood as an indication where the light reception elements 261 to 266 do not meet the condition that "the light reception values ​​of all optical axes are the first threshold or higher," that is, they are only in a determined OFF state. A horizontal axis is introduced in this drawing to illustrate this indication. The horizontal axis shows the result of the individual light reception determination for each optical axis (= the number of optical axes that were determined to be in the light-shielding state by individual optical axis determination).Note that an OFF state of the OSSD indicates a state in which the condition that "the light reception levels of all optical axes are the first threshold or higher" is not met for the light reception elements 261 to 266, and the OSSD output is OFF. For the sake of simplicity, in the present embodiment, a state in which the light reception elements 261 to 266 do not meet the condition that "the light reception levels of all optical axes are the first threshold or higher"—that is, a state in which "the light reception levels of at least one or more optical axes are lower than the first threshold"—is considered the determined OFF state. This means that in the determined ON state, the number of optical axes in the light-shielding state is 0. Conversely, in the determined OFF state, the number of optical axes in the light-shielding state is 1 or more.

[0110] Note that the individual determination of light received quantity for each optical axis is only performed in the determination-ON state (indicator color: green) and the determination-OFF state (indicator color: red). Therefore, performing this determination in a flowchart described later is the same step as comparing the average light received quantity with the threshold value.

[0111] Furthermore, in the ON and OFF states, a threshold value is shifted as a criterion for switching the number of indicator lamp sources 170a, 170b, and 170c that are switched on. First, the ON state is described. As described above, the ON state is a state in which the light received by all optical axes is at or above the first threshold value. Therefore, in the ON state, threshold values ​​for switching the number of indicator lamp sources that are switched on (a fourth and a fifth threshold value in this diagram) are provided within a range where the average light received is relatively high.

[0112] Referring to this diagram, if the average light received is lower than the fourth threshold in the ON state, one green light is illuminated (= a state in which only indicator lamp 170a is illuminated in green). If the average light received is higher than the fourth threshold and lower than the fifth threshold, two green lights are illuminated (= a state in which indicator lamp sources 170a and 170b are illuminated in green). If the average light received is higher than the fifth threshold, three green lights are illuminated (= a state in which indicator lamp sources 170a, 170b, and 170c are illuminated in green). That is, as the average light received increases, the number of illuminated green lights also increases.

[0113] Note that as the distance between light source 100 and light receiver 200 increases, the amount of light received on each optical axis decreases. Although light source 100 and light receiver 200 are arranged in parallel and can normally receive light without impurities, it is also conceivable that the amount of light received decreases simply due to an increase in the distance between light source 100 and light receiver 200.

[0114] If the number of indicator lamp sources 170a, 170b, and 170c that are switched on is reduced in such a situation, information regarding installation and maintenance cannot be transmitted correctly. Therefore, it is desirable to adjust the threshold to extend the range in which the number of indicator lamp sources 170a, 170b, and 170c that are switched on is 3. Referring to this drawing, in the ON state, the fifth threshold for switching the number of indicator lamp sources 170a, 170b, and 170c that are switched on is set relatively low between three and two.

[0115] Next, the off-state is described. Switching the display pattern in the off-state is useful when light transmitter 100 and light receiver 200 are installed. For example, consider a case where the installation positions of light transmitters 100 and 200 are set starting from the off state, in which the number of illuminated indicator light sources is 0. In this case, it is desirable for the display pattern to switch even if the average amount of light received increases or decreases slightly, in order to detect the directional dependence of the setting (i.e., whether the installation positions are close to the correct installation positions or not).

[0116] Thus, in the OFF state, the thresholds (the first, second, and third thresholds in this drawing) are provided for switching the number of indicator lamp sources turned on in an area where the average amount of light received is relatively low. For example, a relationship between the thresholds can be first threshold < second threshold < third threshold < fourth threshold < fifth threshold, as shown in this drawing. In the embodiment shown in this drawing, the first, second, and third thresholds do not affect the switching of the number of indicator lamp sources turned on in the ON state.

[0117] Referring to this diagram, if the average light received is lower than the first threshold in the OFF state, the state becomes the OFF state (a state in which indicator lamp sources 170a, 170b, and 170c are off), as described above. If the average light received is higher than the first threshold and lower than the second threshold, one red light is switched on (a state in which only indicator lamp source 170a is switched on in red). If the average light received is higher than the second threshold and lower than the third threshold, two red lights are switched on (a state in which indicator lamp sources 170a and 170b are switched on in red).If the average light reception is higher than the third threshold, three red lights are switched on (= a state in which the indicator lamp sources 170a, 170b and 170c are switched on in red). That is, if the average light reception increases, the number of switched-on red lights increases.

[0118] As described above, the purpose of switching the display pattern in the ON and OFF states differs depending on the amount of light received on the optical axis. Specifically, it is assumed that switching the display pattern to green light in the ON state is useful for detecting dirt accumulation (maintenance requirements) after the light curtain 1 has been in operation. Conversely, switching the display pattern to red light in the OFF state is useful for optical axis alignment when the light curtain 1 is installed. Therefore, to set individually optimal thresholds for the ON and OFF states, it is desirable to shift the thresholds between these states.

[0119] However, in contrast to the description above, it is also advantageous to align the thresholds between the ON state and the OFF state. For example, in this drawing, from the perspective of the average light reception, "one green light is on" in the ON state and "three red lights are on (or two red lights are on)" in the OFF state are adjacent. Therefore, if the optical axis is blocked and the ON state is switched to the OFF state while maintaining the average light reception, the display pattern will change from "one green light is on" to "three red lights are on (or two with red lights on)."

[0120] This means that if one focuses solely on the number of lights switched on, there is a possibility that the display pattern will switch with a feeling of unease, as if the number of lights on increases even though the optical axis is shielded. Therefore, if the goal is to communicate the amount of light received by the optical axis in an easily understandable way, it can be said that it is desirable to adjust the thresholds between the ON and OFF states in such a way that a reverse effect in the number of lights switched on does not occur.

[0121] Fig. Figure 14 is a diagram illustrating the relationship between the amount of light received on the optical axis (minimum amount of light) and the display pattern. As shown in this diagram, the determining criterion for the display pattern can be a minimum value (= minimum amount of light) of the amount of light received on each optical axis.

[0122] In this case, for example, a first threshold, a second threshold, and a third threshold are defined as threshold settings. A relationship between the thresholds can be: first threshold < second threshold < third threshold.

[0123] Regarding this diagram, if the minimum light level is lower than the first threshold, three red lights are illuminated (= a state in which indicator lamp sources 170a, 170b, and 170c are illuminated in red). This state corresponds to the off-determination state. As described above, in the off-determination state, the number of illuminated red lights is fixed at three. If the minimum light level is higher than the first threshold and lower than the second threshold, one green light is illuminated (= a state in which only indicator lamp source 170a is illuminated in green). If the minimum light level is higher than the second threshold and lower than the third threshold, two green lights are illuminated (= a state in which indicator lamp sources 170a and 170b are illuminated in green).If the minimum light level is higher than the third threshold, three green lights are switched on (= a state in which the indicator lamp sources 170a, 170b and 170c are switched on in green). That is, if the minimum light level increases, the number of switched-on green lights also increases.

[0124] As described above, an average value (= average amount of light received) of the amounts of light received in the optical axes can be assumed as a determining criterion for determining the display pattern, or the minimum value (= minimum amount of light received) can be assumed. <Eingeschaltetes Bild>

[0125] Fig. Figure 15 is a diagram illustrating an illuminated image (first example) of the light curtain 1. This drawing shows the second embodiment described above ( Fig. 9 and Fig. 10) as an example arrangement and display pattern of the indicator lamp sources 170a, 170b and 170c. Furthermore, the relationship between the amount of light received on the optical axis and the display pattern is based on the above with reference to Fig. The switching control described in section 13 of the display pattern is assumed.

[0126] First, the operating-OFF state (four states on the left side of this diagram) is described. In a complete light-shielding state, the light curtain 1 is switched off (= a state in which the indicator lamp sources 170a, 170b, and 170c are switched off). At a low light level, one red light is switched on (= a state in which only the indicator lamp source 170a is switched on red). At a medium light level, two red lights are switched on (= a state in which the indicator lamp sources 170a and 170b are switched on red). At a high light level, three red lights are switched on (= a state in which the indicator lamp sources 170a, 170b, and 170c are switched on red).

[0127] Next, the determining ON state (three states on the right side of this diagram) is described. At low light level, one green light is switched on (= a state in which only indicator lamp 170a is switched on in green). At medium light level, two green lights are switched on (= a state in which indicator lamp sources 170a and 170b are switched on in green). At high light level, three green lights are switched on (= a state in which indicator lamp sources 170a, 170b, and 170c are switched on in green).

[0128] Note that a light diffuser is positioned over each of the indicator lamp sources 170a, 170b, and 170c. Therefore, it is desirable to adjust the arrangement and display pattern of the indicator lamp sources 170a, 170b, and 170c so that the switching of the display pattern can also be detected by the light diffuser. This point is also as described above.

[0129] Fig. Figure 16 is a diagram illustrating an illuminated image (second example) of the light curtain 1. In this drawing, a bar graph of the light curtain 1 is displayed according to the amount of light received on the optical axis. Specifically, each of the three substrates 190x, 190y, and 190z, which are cascaded along the longitudinal direction of the light curtain 1 (more precisely, a group of indicator lamp sources 170 embedded therein), is controlled as an individual unit to be switched on or off.

[0130] First, the operating-OFF state (four states on the left side of this diagram) is described. In a complete light-shielding state, light curtain 1 is switched off (= a state in which substrates 190x, 190y, and 190z are switched off). At low light levels, 1 / 3 of light curtain 1 is switched on with a red bar (= only substrate 190x is switched on in red). At medium light levels, 2 / 3 of light curtain 1 is switched on with a red bar (= a state in which substrates 190x and 190y are switched on in red). At high light levels, the entire light curtain 1 (3 / 3) is switched on with a red bar (= a state in which substrates 190x, 190y, and 190z are switched on in red).

[0131] Next, the determining ON state (three states on the right side of this diagram) is described. At low light intensity, 1 / 3 of light curtain 1 is switched on with a green bar (= only substrate 190x is switched on in green). At medium light intensity, 2 / 3 of light curtain 1 is switched on with a green bar (= substrates 190x and 190y are switched on in green). At high light intensity, the entire light curtain 1 (3 / 3) is switched on with a green bar (= a state in which substrates 190x, 190y, and 190z are switched on in green).

[0132] As described above, in the activated image of the second example ( Fig. 16) The switching of the display pattern according to the amount of light received on the optical axis is easier to perceive compared to the first example described above ( Fig. 15) Note that in a case where the above-described turned-on image is realized based on the configuration in which the multiple substrates 190x, 190y and 190z are cascaded, the degree of design difficulty and cost may increase. <Modifikation des Anzeigemusters entsprechend der Lichtempfangsmenge auf der optischen Achse>

[0133] The above description illustrates a configuration in which the number (specifically, the interval between interruptions) of the 170 illuminated indicator lamp sources is switched according to the amount of light received on the optical axis. However, various other modifications are conceivable.

[0134] For example, the timing of indicator lamp 140 (e.g., whether it is constantly on, flashes at 1-second intervals, or flashes at 2-second intervals) can be changed according to the amount of light received on the optical axis. Furthermore, the amount or color of light emitted by indicator lamp 140 can also be changed according to the amount of light received on the optical axis. In a case where these aspects are considered, it is not necessary to individually control the multiple indicator lamp light sources 170 at the time of changing the display pattern. Thus, for example, an optical fiber can be used as the indicator lamp 140. <Funktionsblock (mit Anzeigemustersteuerfunktion)>

[0135] Fig. Figure 17 is a functional block diagram of light curtain 1 with a display pattern control function. Note that in this drawing, with reference to the one described above... Fig. 5, Control systems of the indicator lamp sources 170a, 170b and 170c and the indicator lamp sources 270a, 270b and 270c instead of light emission and light reception systems of the optical axes Oax1 to Oax6 are the focus.

[0136] Furthermore, according to the second embodiment described above ( Fig. 9 and Fig. 10) the indicator lamp sources 170a, 170b and 170c and the indicator lamp sources 270a, 270b and 270c arranged as a set of three in the sequence shown (in the order of a, b, c, a, b and c from the top of this drawing).

[0137] Control circuit 181 controls the two indicator lamp light sources 170a by means of a common control signal. The same applies to indicator lamp light sources 170b and 170c. Furthermore, control circuit 281 controls the two indicator lamp light sources 270a by means of a common control signal. The same applies to indicator lamp light sources 270b and 270c.

[0138] Note that the light received by each of the optical axes Oax1 to Oax6 is compared with the threshold value in the control circuit 281. In this case, the control circuit 281 may contain an analog-to-digital converter that converts an analog signal output by each of the light receiving elements 261 to 266 into a digital signal. Additionally, the control circuit 281 may contain a computation circuit that calculates an average value (= average light received) or a minimum value (= minimum light received) from the light received by each of the optical axes Oax1 to Oax6.

[0139] Control circuit 281 performs on / off control of each of the indicator lamp sources 270a, 270b, and 270c based on a comparison between the average (or minimum) light received and the threshold value. Furthermore, control circuit 281 transmits the comparison result to control circuit 181 via communication circuits 282 and 182. Control circuit 181 then performs on / off control of each of the indicator lamp sources 170a, 170b, and 170c based on the comparison result transmitted by control circuit 281. <verarbeitungsablauf>

[0140] Fig. Figure 18 is a diagram illustrating a processing flow of the display pattern control based on the average amount of light received. When the processing flow of this drawing is started, in step S1 the optical axis to be driven, Oax(i) (where i = 1, 2, ..., and imax(6) and an initial setting value i = 1), is set.

[0141] In the subsequent step S2, the light projection element 16i is switched on. That is, first the light projection element 161 is switched on to form the optical axis Oax1.

[0142] In step S3, it is determined whether the amount of light received Li in the light receiving element 26i is greater than the first threshold. Note that, as described above, the first threshold corresponds to the threshold used to determine whether each of the optical axes Oax1 to Oax6 is in the light-shielding state. The process then proceeds to step S4 if a "yes" determination is made. Conversely, the process proceeds to step S8 if a "no" determination is made. In step S8, the safety output (OSSD) is switched to the OFF state without waiting for the display pattern control to complete. This allows for the immediate shutdown of a hazard such as a press. Additionally, in step S8, besides the safety output (OSSD) being switched to the OFF state, the display aspect of the OSSD indicator lamp can be changed according to the safety output (OSSD) being switched to the OFF state.Note that steps S3 and S8 are not directly related to the display pattern control. Therefore, steps S3 and S8 are represented by dashed lines in this drawing.

[0143] If a YES determination is made in step S3, the amount of light received Li is recorded in a register or the like in step S4.

[0144] In the subsequent step S5, it is determined whether the optical axis is the last optical axis (that is, i = imax(6)). If the answer is YES, the process continues to step S6. Conversely, if the answer is NO, the process returns to step S1 after incrementing the variable i by one (++i). Steps S1 through S5 are then repeated until a YES answer is reached in step S5.

[0145] If a "yes" determination is made in step S5, a comparison is performed in step S6 between the average value (= average light reception quantity) or the minimum value (= minimum light reception quantity) of the light reception quantities and the multitude of threshold values. The comparison in this step was carried out with reference to the above-described Fig. 13 and Fig. 14 described. Therefore, the superfluous description is omitted.

[0146] In the subsequent step S7, the switched-on state (display pattern) of each of the indicator lamps 140 and 240 is updated according to the comparison result obtained in step S6. The process then returns to step S1, and the processing sequence is repeated.

[0147] Note that this diagram is drawn with the understanding that in step S6, comparative processing can be performed between the average value (= average light reception) of the light reception amounts and the multitude of threshold values. That is, the comparative processing in step S6 is not performed for each optical axis, but rather after the light reception amounts of all optical axes have been recorded.

[0148] However, in a case where the comparison processing is performed between the minimum value (= minimum light received quantity) and the multitude of threshold values, step S5 can be omitted. That is, the comparison processing in step S6 can be performed sequentially for each optical axis at one time point in time, without waiting for the light received quantities of all optical axes to be recorded.

[0149] For example, if the amount of light received by the first light receiving element 261 is the second threshold or less, it is sufficient to switch to a green light (= a state in which only the indicator lamp source 170a is switched on in green) without comparing the amount of light received by each of the other light receiving elements 262 to 266 with the threshold (see Fig. 14). Accordingly, the subsequent comparison processing can be omitted. <zusammenfassung>

[0150] In the above described Fig. In sections 9 to 18, the light curtain 1 with the function of switching the display pattern according to the amount of light received on the optical axis was proposed. Briefly, this configuration can be described as: “A light curtain comprising a housing with a metal casing in which an element of a pair consisting of a light-projecting element and a light-receiving element, forming a plurality of optical axes, is arranged inside along a longitudinal direction and extends in the longitudinal direction, and end pieces connected to both ends of the metal casing to form the plurality of optical axes at intervals from one another; a cover that allows light from the light projection element to pass through and is attached to the housing in such a way that it intersects the multitude of optical axes; an indicator lamp, which is a light-diffusing element, arranged outwards from an outer surface of at least one of the cover and the housing along the longitudinal direction or formed in series with the cover; and a display lamp source that is housed inside the casing and provides light for display in the direction of the display lamp, wherein, when an operating indicator lamp mode is set, the indicator lamp source performs an on or off control in a display pattern corresponding to a light emission color corresponding to an operating state of the light curtain and a light reception quantity of the light receiving element" are expressed. <Fünfte Ausführungsform>

[0151] Fig. Figure 19 is a diagram illustrating a configuration example of a light curtain 1 according to a fifth embodiment. The light curtain 1 of the present embodiment comprises a pair of a light transmitter 100 and a light receiver 200.

[0152] As described above, the light source 100 comprises a plurality of light projection elements 161 to 166. Furthermore, the light receiver 200 is arranged opposite the light source 100 and comprises a plurality of light receiving elements 261 to 266, which receive light rays projected by the plurality of light projection elements 161 to 166. For the sake of simplicity, however, this drawing only shows optical axes Oax1 to Oax6 formed between the light projection elements 161 to 166 and the light receiving elements 261 to 266. The light projection elements 161 to 166 and the light receiving elements 261 to 266 are described with reference to the optical axes Oax1 to Oax6 described above. Fig. 3 and Fig. 5 described.

[0153] Light curtain 1 emits a safety signal generated based on whether each of the multiple optical axes Oax1 to Oax6, formed between light transmitter 100 and light receiver 200, is in a light-shielding state, that is, whether it is emitting the OSSD signal described above to the outside world. It goes without saying that the number of optical axes Oax1 to Oax6 is arbitrary.

[0154] Furthermore, the light curtain 1 includes a synchronization unit that synchronizes the light projection time of each of the light projection elements 161 to 166 in the light transmitter 100 with the light reception time of each of the light reception elements 261 to 266 in the light receiver 200 by means of optical communication. That is, an optical synchronization system is assumed to be the synchronization system for the light projection and light reception times in the light curtain 1.

[0155] Referring to this drawing, the optical axes Oax1 and Oax6, formed at both the upper and lower ends of the light curtain 1, can be redirected for time synchronization under the optical axes Oax1 to Oax6 for light incidence detection and light shielding detection. For example, the light transmitter 100 can transmit the synchronization pulse via optical axis Oax1 before the start of the optical axis scanning in order to sequentially detect the light incidence and light shielding of each of the optical axes Oax1 to Oax6. As described above, the synchronization pulse is a pulse signal for time synchronization and has a specific pulse pattern. The light receiver 200 synchronizes the light reception time so that it coincides with the light projection time of the synchronization pulse.

[0156] The optical synchronization system is adopted, and therefore cabling between the projector 100 and the light receiver 200 is unnecessary. Accordingly, one degree of freedom in the cabling of the light curtain 1 can be increased.

[0157] Furthermore, the light curtain 1 includes indicator lamps 140 and 240. Indicator lamp 140 is located in the light transmitter 100. Indicator lamp 240 is located in the light receiver 200. Indicator lamps 140 and 240 can function as operating indicator lights to show the operating status of the light curtain 1. A worker can visually determine the operating status of the light curtain 1, for example, whether the OSSD output is on or off, by looking at indicator lamps 140 and 240 of the light curtain 1.

[0158] Furthermore, the light curtain 1 includes a locking and indicator unit for locking and indicating the indicator lamps 140 and 240 by optical communication from the light receiver 200 to the light transmitter 100. With reference to this drawing, optical axes Com1 and Com2 for locking and indicator control between the light transmitter 100 and the light receiver 200 are formed separately from the optical axes Oax1 to Oax6 for light incidence detection, light shielding detection, and time synchronization.

[0159] Note that the optical axes Com1 and Com2 can be formed, for example, near both the upper and lower ends of the light curtain 1. Referring to this drawing, the optical axis Com1 is formed between the optical axis Oax1 and the optical axis Oax2. Additionally, the optical axis Com2 is formed between the optical axis Oax5 and the optical axis Oax6. However, one of the optical axes Com1 and Com2 can be omitted. Furthermore, the optical axes Com1 and Com2 can be formed in the upper and lower central regions of the light curtain 1.

[0160] Fig. Figure 20 is a schematic diagram illustrating an example of optical axis formation. As shown in this drawing, the light curtain 1 of the present embodiment comprises at least one pair of a light projection element 160 and a light receiving element 260, which are provided for locking and display control of the indicator lamps 140 and 240, separate from at least one pair of a light projection element 310 and a light receiving element 320, which are provided for light incident detection and light shielding detection. In addition, the control circuits 181 and 281 described above are shown in this drawing as units that integrate the complete operation of each of the light transmitters 100 and the light receiver 200.

[0161] The light projection element 160 is an optical element provided in the light transmitter 100. The light projection element 160 can be understood as the light projection elements 161 to 166 described above. The light projection element 160 can, for example, be a light-emitting diode (LED). The light receiving element 260 is an optical element provided in the light receiver 200. The light receiving element 260 can be understood as the light receiving elements 261 to 266 described above. The light receiving element 260 can, for example, be a photodiode or a phototransistor. An optical axis Oax for light incidence detection and light shielding detection or time synchronization is formed between the light projection element 160 and the light receiving element 260. The optical axis Oax corresponds to the optical axes Oax1 to Oax6 described above.

[0162] The light projection element 310 is an optical element provided in the light receiver 200. The light projection element 310 can, for example, be a light-emitting diode (LED). The light receiving element 320 is an optical element provided in the light transmitter 100. The light receiving element 320 can, for example, be a photodiode or a phototransistor. An optical axis Com for locking and display control, which differs from the optical axis Oax, is formed between the light projection element 310 and the light receiving element 320. The optical axis Com corresponds to the optical axes Com1 and Com2 described above.

[0163] Control circuits 181 and 281 lock and display indicator lamps 140 and 240 by means of optical communication for locking and display control using the optical axis Com, which is formed between the light projection element 310 and the light receiving element 320. Note that the optical axis Com can be understood as the optical communication path from the light receiver 200 to the light transmitter 100.

[0164] For example, the control circuit 281 of the light receiver 200 determines the on or off state of the OSSD output depending on whether the optical axis Oax, formed between the light projection element 160 and the light receiving element 260, is in the light-shielding state. The control circuit 281 then performs on or off control of the indicator lamp source 270 according to the on or off state of the OSSD output. At this point, the control circuit 281 drives the light projection element 310 to transmit the on or off state of the OSSD output to the light transmitter 100. The control circuit 181 of the light transmitter 100 performs on or off control of the indicator lamp source 170 according to the on or off information of the OSSD output received by the light receiving element 320.

[0165] In the light curtain 1 of the present embodiment, the indicator lamps 140 and 240 can be locked and displayed without the need for wiring between the light transmitter 100 and the light receiver 200. Accordingly, the visibility of the indicator lamps 140 and 240 can be improved while utilizing the advantages of the optical synchronization system.

[0166] Note that, as described above, the optical axis Com for locking and display control can be formed as a dedicated optical axis separate from the optical axis Oax for light incidence detection and light shielding detection or time synchronization. This configuration increases one degree of freedom in the design of both the light projection element 310 and the light receiving element 320. Furthermore, in a configuration where the optical axis Oax and the optical axis Com are formed separately, one degree of freedom in the design, such as the number of light projection pulses or the pulse interval, increases.

[0167] For example, for the optical axis Oax for light incidence detection and light shielding detection, in order to accurately detect the light shielding state, a light projection scattering angle of the light projection element 160, a light reception viewing angle of the light reception element 260, a size of a lens provided in a light guidance path from each of the light projection element 160 and the light reception element 260, and the like may be strictly limited by safety standards.

[0168] On the other hand, the restriction described above is not imposed on the optical axis Com for locking and display control. For example, the light projection element 310 can be designed to have a larger light projection spread angle than the light projection element 160. Furthermore, the light receiving element 320 can be designed to have a larger light receiving viewing angle than the light receiving element 260. Additionally, a lens provided in the light path of both the light projection element 310 and the light receiving element 320 can be designed to be larger than the lens provided in the light path of both the light projection element 160 and the light receiving element 260.

[0169] According to such a design, the optical axis Com is easily established between the light transmitter 100 and the light receiver 200. Accordingly, for example, if the alignment of the optical axis is carried out during the installation of the light curtain 1, the locking and display of the indicator lamps 140 and 240 can be performed quickly. As a result, since the status indicator (see Fig. 13 or Fig. 14), which is locked on the optical axis with the amount of light received described above, the alignment of the optical axis can be easily carried out.

[0170] Note that, for example, in the above described Fig. 5. If at least one pair of light projection elements and light receiving elements, among the light projection elements 161 to 166 and the light receiving elements 261 to 266, is exchanged between the light transmitter 100 and the light receiver 200, it is not impossible to use one optical axis for both light incidence detection and light shielding detection, as well as for interlocking and display control in a time-division multiplexing method. According to the present modification, since the light projection element 310 and the light receiving element 320 are omitted, this can contribute to a cost reduction of the light curtain 1. However, at least some of the light incidence and light shielding information of the optical axes Oax1 to Oax6 is received not by the light receiver 200, but by the light transmitter 100.Accordingly, in order to output the OSSD through the light receiver 200, optical communication is also required to transmit the light incidence and light shielding information received from the light transmitter 100 to the light receiver 200.

[0171] Furthermore, multiple sets of the light projection element 310 and the light receiving element 320 can be provided. For example, as described above. Fig. Figure 19 shows a plurality of optical axes Com1 and Com2 for locking and display control. With this configuration, even if one of the optical axes Com1 and Com2 is blocked, information transmission from the light receiver 200 to the light transmitter 100 can continue.

[0172] Fig. Figure 21 is a diagram illustrating the processing sequence of the locking and display control. In the processing sequence shown in this drawing, the actuation is changed in step S7, and steps S9 to S11 are subsequently changed after step S7 to the one described above. Fig. 18 added. The following mainly describes processing content after step S7 and subsequent steps.

[0173] In step S7, the light receiver 200 determines an on state (display pattern) for each of the indicator lamps 140 and 240 according to the comparison result obtained in step S6. The process then continues with step S9 without returning to step S1.

[0174] In step S9, the light receiver 200 performs a pulse drive of the optical axis Com to project pulse information corresponding to the switched-on state (display pattern) determined in step S7. That is, after the light incident and light shielding states of all optical axes Oax(i) have been detected, the light receiver 200 performs optical communication that reflects the detection result. The aforementioned pulse information could, for example, be a specific pulse pattern.

[0175] Subsequently, in step S10, the light transmitter 100 receives the pulse information via the optical axis Com and compares the pulse information with predetermined internal information. Note that the internal information can be a table that links the pulse information to the on or off state of the indicator lamp 140.

[0176] In the subsequent step S11, the light transmitter 100 updates the switched-on state (display pattern) of the indicator lamp 140 according to the comparison result in step S10, that is, the determined content in step S7. Furthermore, the light receiver 200 updates the switched-on state (display pattern) of the indicator lamp 240 according to the comparison result in step S6 and the determined content in step S7. This control enables the locking and display of the indicator lamps 140 and 240.

[0177] Note that after the on state (display pattern) of each of the indicator lamps 140 and 240 is updated, the process returns to step S1, and the processing sequence is repeated.

[0178] Fig. 22 and Fig. Figure 23 shows a top view and a perspective view illustrating a configuration example of the light receiver 200. In both drawings, the longitudinal direction of the light receiver 200 is the X-axis, the transverse direction is the Y-axis, and the thickness direction (depth direction) is the Z-axis.

[0179] Fig. Figure 22 can be understood as an xy-view top view of the light receiver 200, viewed from the front. Furthermore, Fig. Figure 23 can be understood as a perspective view in which the light receiver 200 is slightly rotated around the X-axis, so that the z-axis of Fig. 22 is inclined towards the back of the drawing.

[0180] However, it illustrates Fig. 23 a state in which a metal housing 211 and an end cap 212 of the light receiver 200 are removed. Accordingly, represents Fig. 23 represents a substrate 190 and a holder 216, which are contained within the metal housing 211 and the end cap 212.

[0181] As shown in both drawings, a plurality of lenses 214 are arranged at equal intervals along a longitudinal direction of the light receiver 200 on a front face of the light receiver 200. Each of the plurality of lenses 214 forms a light-guiding path (light-receiving path) of the optical axis Oax. All of the plurality of lenses 214 are supported by the holder 216. Note that among the plurality of lenses 214, some lenses 214 may be positioned at locations corresponding to a front face of the end cap 212.

[0182] Furthermore, among the plurality of lenses 214, a lens 215 can be provided between two adjacent lenses 214. The lens 215 forms a light-guiding path (light projection path) of the optical axis Com. The lens 215 is supported by the holder 216. The optical axis Com can be formed, for example, near both ends of the light curtain 1. In this drawing, the lens 215 is positioned at a location corresponding to the front face of the end cap 212. One size of the lens 215 can be designed to be larger than any size of the plurality of lenses 214.

[0183] Fig. Figure 24 is a diagram illustrating an example of mutual light interference between a light curtain 1A and a light curtain 1B. Light curtain 1A comprises a pair of a light source 100A and a light receiver 200A. Light curtain 1B comprises a pair of a light source 100B and a light receiver 200B.

[0184] Light curtains 1A and 1B are installed such that the light transmitter 100A of light curtain 1A and the light transmitter 100B of light curtain 1B are back-to-back. Viewed from another perspective, light curtains 1A and 1B are installed such that the light receiver 200A of light curtain 1A and the light receiver 200B of light curtain 1B are opposite each other.

[0185] In such an installation, it is less likely that an optical axis OaxA emitted by light transmitter 100A of light curtain 1A will be received by light receiver 200B of light curtain 1B. Furthermore, it is less likely that an optical axis OaxB emitted by light transmitter 100B of light curtain 1B will be received by light receiver 200A of light curtain 1A.

[0186] However, as described above, in light curtains 1A and 1B, the light receiver 200A of light curtain 1A and the light receiver 200B of light curtain 1B are positioned opposite each other. Therefore, an optical axis ComA emitted by light receiver 200A of light curtain 1A can be received by light receiver 200B of light curtain 1B. Furthermore, an optical axis ComB emitted by light receiver 200B of light curtain 1B can be received by light receiver 200A of light curtain 1A. Consequently, problems may arise in the detection of light incidence and light shielding along the optical axes OaxA and OaxB.

[0187] In light of the above considerations, an optical axis drive control is proposed below which is capable of suppressing mutual light interference.

[0188] Fig. Figure 25 is a diagram illustrating an example of optical axis control. As shown in this drawing, the light curtain 1 of the present embodiment repeats drive periods T1 and T2 in a time-division multiplexing method as the control mechanism for the optical axes Oax and Com. The optical axis Oax can be understood as one of the optical axes OaxA and OaxB described above. The optical axis Com can be understood as one of the optical axes ComA and ComB described above.

[0189] The drive period T1 can be understood as the time period during which the light projection element 160 and the light receiving element 260 are driven; that is, a time period during which the optical axis Oax between the light projection element 160 and the light receiving element 260 is established and light incidence detection and light shielding are performed. The drive period T1 can have a length that depends on the number i of optical axes Oax, for example, several ms (= several tens of µs × i).

[0190] The drive period T2 can be understood as the time period during which the light projection elements 310 and 320 are driven; that is, a time period during which the optical axis Com between the light projection element 310 and the light receiving element 320 is established and the pulse information for locking and display control is transmitted. The drive period T2 can have a length depending on the amount of information to be transmitted, for example, several hundred µs.

[0191] Furthermore, as shown in this diagram, a sampling period Ts can encompass the drive periods T1 and T2. However, the drive period T2 can be skipped once per sampling period Ts, or a multiple of them. This means that optical communication using the optical axis Com can be performed after the light incidence and light shield detection of the optical axis Oax have been repeated two or more times. In other words, the optical communication interval can be set longer than the optical axis detection interval.

[0192] In this case, since the frequency of interference of the optical axis Com with respect to the detection of the optical axis Oax is once or less every two times, the light receiver 200 can operate in such a way that it ignores the influence of interference of the optical axis Com.

[0193] According to this control, it is possible to suppress the mutual light interference that can occur between light curtain 1A and light curtain 1B, even under a Fig. 24 situations depicted.

[0194] Note that in this diagram, for the sake of simplicity in the description, the skipped drive period T2 is represented by a dashed frame. Thus, the length of the sampling period Ts appears to be constant regardless of whether the drive period T2 is skipped or not. In reality, the sampling period Ts can be shortened by the skipped drive period T2, causing the next drive period T1 to arrive earlier.

[0195] According to such an optical axis drive control, it is possible to implement the locking and display control of indicator lamps 140 and 240 while keeping the response time of the OSSD output as short as possible. Note that a skip frequency of the drive period T2 only affects the response time of each of the indicator lamps 140 and 240, that is, the update frequency of the on or off state. Accordingly, the skip frequency of the drive period T2 can be set relatively freely.

[0196] Furthermore, as another method for suppressing mutual light interference, the optical axes Oax and Com can have different wavelengths. For example, the optical axis Oax can be formed by infrared light, and the optical axis Com can be formed by red light. In this case, a lens that directs the optical axis Com to the light receiving element 320 of the light source 100 can be subjected to filtering to block infrared light. According to this configuration, the penetration of the optical axis Oax into the light receiving element 320 can be suppressed. <Nichtherstellung der optischen Kommunikation>

[0197] In a case where a specific pulse pattern is not received by the light receiving element 320 due to light shielding of the optical axis Com or the like, optical communication using the optical axis Com cannot be established. Furthermore, even in a case where an unexpected pulse pattern is received by the light receiving element 320 due to mutual light interference or the like, optical communication using the optical axis Com may still not be established.

[0198] In a case where optical communication via the optical axis Com is not established during the drive period T2, the light transmitter 100 falls into a state in which the light incidence and light shielding state of the light receiver 200 cannot be known. In such a case, the indicator lamp 140 can be retained in its previous display state. According to this control, it is less likely that the locking and display of the indicator lamps 140 and 240 will be disrupted if optical communication is temporarily lost.

[0199] However, indicator lamp 140 can be switched to the off state if optical communication via optical axis Com is continuously lost over a large number of drive cycles T2. According to such a control system, it is possible to notify the operator that optical communication has been lost. By switching to the off state, it is possible to directly inform the user that optical communication via optical axis Com has failed.

[0200] Furthermore, in a case where the optical axis Com is positioned between the optical axis Oax(i) and the optical axis Ox(i+1), it is unlikely that only the optical axis Com will be shielded. Therefore, if optical communication via the optical axis Com is not continuously established over the multitude of drive periods T2, the indicator lamp 140 may switch to a display state indicating the OSSD output is off, for example, a state with the red light on. However, if the light curtain is aligned with the optical axis, in a case where the light curtain is in the red light-on state when optical communication via the optical axis Com is not established, the user may be confused regarding the meaning of red.Therefore, as described above, it is preferable to switch to the off state if optical communication of the optical axis Com is not established. Note that indicator lamp 140 may flash green at the time of locking (the user can easily detect a locked state by the flashing green rather than a solid green light), or it may be lit orange at the time of muting. Since the information displayed by indicator lamp 140 is non-safety-related, not establishing optical communication of the optical axis Com is permissible. In other words, even if optical communication of the optical axis Com is not established, the OSSD will not be switched off.

[0201] In a case where the light transmitter and light receiver are connected in series, the indicator lamp 140 can be operated independently. Specifically, for example, in a case where three light transmitters (light receivers) are connected in series, if optical communication of the optical axis Com in the middle light transmitter (light receiver) is not established, only the middle light transmitter (light receiver) can be caused to perform a non-establishment operation (for example, switching to the off state). All indicator lamps 140 can be operated according to a predetermined optical communication state of the optical axis Com in the light transmitter (light receiver), in addition to independent operation of each unit.For example, in a case where three light transmitters (light receivers) are connected in series, if optical communication of a predetermined optical axis Com is not established, all indicator lamps 140 can be switched to the off state.

[0202] Furthermore, as described above, two optical axes Com are provided for a light transmitter (light receiver) according to the present embodiment. In a case where the information from the two optical axes Com does not match, it is conceivable to switch to different switched-on states. For example, if only one of the optical axes Com is manufactured, the indicator lamp 140 can be switched based on the information from the manufactured optical axis Com. Additionally, if both optical axes Com are manufactured, but their information does not match, a previous state of the indicator lamp 140 can be maintained. <lichtleckage>

[0203] Note that in a case where the optical axis Oax is used for light incidence and light shielding detection and the optical axis Com is used for locking and display control, light leakage may occur via the light transmission paths of the optical axes Oax and Com.

[0204] Fig. Figure 26 is a longitudinal sectional view illustrating an example of the light receiver 200, which includes a light leakage suppression mechanism. This drawing can be understood as a diagram showing an α-α cross-section in the manner described above. Fig. 22 represents, in particular a diagram in which a circumference of the lens 215 is partially magnified.

[0205] In the light receiver 200 of the present configuration example, the plurality of light-receiving elements 260 are arranged on a surface of the substrate 190 at a constant distance d1 along the longitudinal direction of the light receiver 200. Each of the plurality of light-receiving elements 260 can be understood as an optical element for detecting the optical axis Oax, which enters from outside the light receiver 200 through the plurality of lenses 214.

[0206] Furthermore, the light projection element 310 is arranged on the surface of the substrate 190 between two adjacent light receiving elements 260. The light projection element 310 can be understood as an optical element that emits the optical axis Com for locking and display control via the lens 215 to the outside of the light receiver 200.

[0207] In this case, as indicated by a solid arrow in this drawing, optical axis Oax light leakage can occur in the form of an ingress in the opposite direction from the light path of the light projection element 310, bypassing the light receiving element 260. In such a case, the optical axis Oax may be incorrectly detected at the light receiving element 260, which is adjacent to the light projection element 310. Specifically, the incident light is falsely detected even though the optical axis Oax, which should be incident on the light receiving element 260, is blocked by an object M. In such a situation, a very dangerous condition can arise because a correct OSSD output is not generated.

[0208] Therefore, the light receiver 200 of the present configuration example includes a light-shielding wall 330. The light-shielding wall 330 is shaped to shield the light that travels around the light-receiving element 260 from the light-guiding path of the light-projecting element 310. For example, the light-shielding wall 330 can be shaped to surround a perimeter of the light-projecting element 310. With this configuration, the light leakage of the optical axis Oax is suppressed. Accordingly, it is possible to improve the reliability of the light curtain 1 by reducing the erroneous detection of the optical axis Oax in the light-receiving element 260.

[0209] Note that the light-shielding wall 330 can be molded as a single piece as part of the holder 216. Alternatively, the light-shielding wall 300 can be formed as an additional part that is attached to the holder 216.

[0210] Furthermore, the light-shielding wall 330 and its circumferential components should reflect as little light as possible from the optical axis Oax. For example, the substrate 190 and the holder 216 are preferably blackened.

[0211] Furthermore, as another method for suppressing light leakage, the optical axes Oax and Com can have different wavelengths, as in the method for suppressing mutual light interference. For example, the optical axis Oax can be formed by infrared light, and the optical axis Com can be formed by red light. In this case, the lens 215, which directs the optical axis Com to the outside of the light receiver 200, can be subjected to filtering to block infrared light. According to this configuration, the penetration of the optical axis Oax through the lens 215 can be suppressed. <Andere Modifikationen>

[0212] Note that, in addition to the embodiments mentioned above, various modifications to different technical features disclosed in this specification may be made without departing from the spirit of the invention. That is to say, the embodiments mentioned above are in every respect exemplary and not limiting, and the technical scope of the invention is defined by the claims and includes all modifications that fall within the meaning and scope defined by the claims. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2002-124169

[0011] < / lichtleckage> < / zusammenfassung> < / verarbeitungsablauf> < / anzeigeinhalt> < / funktionsblock> < / lichtsender> < / lichtvorhang>

Claims

[1] A light curtain that includes a light transmitter comprising a variety of initial light projection elements, a light receiver arranged to face the light emitter and comprising a plurality of first light receiving elements configured to receive light beams projected by the plurality of first light projection elements, and a synchronization unit configured to synchronize a light projection time of the light transmitter and a light reception time of the light receiver through optical communication, wherein a safety signal, generated based on whether each of a plurality of optical axes formed between the light emitter and the light receiver is in a light-shielding state, is emitted to an outside world, the light curtain comprising: a first operating indicator light, which is provided in the light transmitter and configured to indicate an operating status of the light curtain; a second operating indicator light, which is provided in the light receiver and configured to indicate the operating status of the light curtain; at least one set of optical elements, provided and configured in each of the light transmitter and light receiver, to lock and indicate the first operating indicator light and the second operating indicator light; and a control circuit configured to lock and display the first operating indicator light and the second operating indicator light using at least one set of optical elements. [2] The light curtain according to claim 1, wherein the at least one set of optical elements comprises a second light projection element provided in the light receiver and a second light receiving element provided in the light transmitter. [3] The light curtain according to claim 2, wherein a plurality of sets of the second light projection element and the second light receiving element are provided. [4] The light curtain according to claim 2, wherein the second light projection element is a light-emitting diode and the second light receiving element is a photodiode or a phototransistor. [5] The light curtain according to claim 2, wherein in the second light projection element at least one of a light projection scattering angle and lens size is larger than the first light projection element, and in the second light receiving element at least one of a light receiving viewing angle and lens size is larger than the first light receiving element. [6] The light curtain according to claim 2, wherein a first optical axis for light incidence detection and light shielding detection or time synchronization is formed between the first light projection element and the first light receiving element, and a second optical axis for locking and display control, which differs from the first optical axis, is formed between the second light projection element and the second light receiving element. [7] The light curtain according to claim 6, wherein a first period, in which each of the first light projection element and the first light receiving element is driven, and a second period, in which each of the second light projection element and the second light receiving element is driven, are repeated in a time-division multiplexing procedure, and The light receiver drives the second optical axis in the second period according to a recognition result of the first optical axis, which is obtained in each of a plurality of the first periods. [8] The light curtain according to claim 7, wherein if optical communication via the second optical axis is not established in the second period, the first operating indicator light is retained in a previous display state. [9] The light curtain according to claim 8, wherein, if optical communication via the second optical axis is not continuously established over a plurality of the second time periods, the first operating indicator light is switched to an off state or to an indicator state that shows an off state of the safety signal. [10] The light curtain according to claim 6, wherein the light receiver comprises a light-shielding wall formed in such a way as to shield light passing around the first light-receiving element from a light-guiding path of the second light-projecting element. [11] The light curtain according to claim 2, wherein the second light projection element is arranged between the plurality of first light receiving elements, and the second light receiving element is arranged between the plurality of first light projection elements.

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