Light curtain

Abstract

The invention provides a light curtain. The light curtain is miniaturized while the dustproof and waterproof performance is maintained. The light curtain includes: a housing having a metal housing extending in a longitudinal direction and an end member fixed to one end of the metal housing, and having one of a pair of light projecting elements and light receiving elements disposed therein, the light projecting elements and the light receiving elements forming a plurality of optical axes in the longitudinal direction; a cover through which the light emitted by the light projecting element passes and which is attached to the housing so as to intersect the plurality of optical axes; a substrate which is disposed in a sealed space formed by the housing and the cover and on which one of the optical elements is mounted; a conductive fixing member which fixes the end member to the metal housing and is electrically connected to the metal housing; and an AC discharge unit that capacitively couples between the metal case and the ground line of the substrate by means of a fixture.

Description

TECHNICAL FIELD

[0001] The present application relates to a light curtain. BACKGROUND

[0002] A light curtain is a form of a multi-optical axis photoelectric sensor. A light curtain detects a person or an object based on whether a plurality of optical axes formed between a light projector and a light receiver are blocked by light.

[0003] For example, a light curtain is used as a means for detecting an intruder in a dangerous area and outputting a stop signal to a machine. Therefore, a light curtain is often used in a dusty or water-splashing environment in a factory where a plurality of machines are installed. A light curtain used in such an environment needs to have a certain level or higher of dust and water resistance.

[0004] Furthermore, among the specifications indicating dust and water resistance, the IP [Ingress Protection] level is widely recognized. In a conventional light curtain, for example, an extrusion-molded product housing in a cross-sectional U shape is adopted, and a certain level or higher of the IP level is ensured by liquid-tightly joining a front cover constituting a light projecting / receiving window to the housing (Japanese Patent Application Publication No. 2004-311384).

[0005] In addition, in order to improve the ruggedness of a light curtain, a metal housing is sometimes adopted. This makes it easier to ensure a higher IP level.

[0006] In addition, in a light curtain, as one of the EMC [electromagnetic compatibility] countermeasures, an alternating current signal such as noise is discharged from a ground line of a control circuit board to a metal housing by capacitive coupling. However, the surface of the metal housing is usually covered with an insulating layer formed by a surface treatment such as painting or anodizing. Therefore, in a conventional light curtain, a terminal is usually pressed against a cut end surface of the metal housing, which is not covered with the insulating layer, to achieve electrical continuity. However, in the above-described conventional structure, in order to extend the terminal to the cut end surface of the metal housing, a circuit board different from the control circuit board or a custom-made part needs to be provided. Therefore, this can have a significant impact on the size and cost of the light curtain.

[0007] For example, in the case where a circuit board on which a capacitor for coupling is mounted is prepared separately from a main control circuit board, two circuit boards need to be accommodated inside the metal housing. Therefore, the size of the metal housing tends to be large. On the other hand, in the case where coupling is performed using a capacitor mounted on the control circuit board, a wire harness or the like needs to be arranged to the cut end surface of the metal housing. Therefore, this can also be a factor that hinders the miniaturization of the metal housing. Furthermore, the cut end surface area of the metal housing is very small. Therefore, it is difficult to ensure stable conduction between the cut end surface of the metal housing and the terminal as it is. SUMMARY

[0008] An object of the present application is to realize a small-sized light curtain while maintaining dustproof and waterproof properties in view of the above-described problems.

[0009] The light curtain of the present application, for example, includes a housing having a metal case extending in a long side direction and an end member fixed to one end of the metal case, one of a pair of light projecting elements and a light receiving element having a plurality of optical axes formed in the long side direction being arranged inside the housing; a cover which transmits light emitted from the light projecting element and is installed in the housing in a manner intersecting the plurality of optical axes; a substrate arranged inside a sealed space formed by the housing and the cover and mounting the one of the optical elements; an electrically conductive fixing member which fixes the end member to the metal case and electrically connects the metal case; and an alternating current discharge portion which performs capacitive coupling between the metal case and a ground line of the substrate via the fixing member.

[0010] Furthermore, other features, elements, steps, advantages, and characteristics will be further clarified through the following detailed description and its related drawings.

[0011] According to the present application, capacitive coupling between the metal case and the ground line is performed via the electrically conductive fixing member for fixing the metal case of the housing and the end member, so that the light curtain can be realized in a small size while maintaining dustproof and waterproof properties. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 FIG. 1 is a diagram showing the overall structure of a light curtain according to the present application; Figure 2 FIG. 2 is a perspective view showing the overall structure of a light projector; Figure 3 FIG. 3 is a front view showing the overall structure of the light projector; Figure 4 FIG. 4 is a perspective view showing one end portion of the light projector; Figure 5 FIG. 5 is a functional block diagram of the light curtain; Figure 6 FIG. 6 is a diagram showing a first embodiment of the light projector; Figure 7 FIG. 7 is a diagram showing an arrangement example of a pilot light source in the first embodiment; Figure 8 FIG. 8 is a diagram showing a new-old comparison of the relationship between the presence or absence of a function expansion and a mounting member; Figure 9 FIG. 9 is a diagram showing the relationship between the presence or absence of a function expansion and the size in the thickness direction; Figure 10 FIG. 10 is a diagram showing a mounting mechanism of an end cover; Figure 11 FIG. 11 is a new-old comparison diagram of a cable connection structure; Figure 12 FIG. 2 is a cross-sectional view showing an example of a cable connection of a direct drawing type; Figure 13 FIG. 3 is a cross-sectional view showing an example of a fixing structure between a metal case and an end cap; Figure 14 FIG. 4 is a view showing a bottom surface of a case, an α-α cross section, and a β-β cross section; Figure 15 FIG. 5 is a view showing an example of a configuration of an alternating current discharge portion; Figure 16 FIG. 6 is a view showing an example of a configuration of a conduction member; Figure 17 FIG. 7 is a cross-sectional view showing an outer shape of a case. DETAILED DESCRIPTION

[0013] <Light curtain> Figure 1 FIG. 1 is a view showing a schematic configuration of a light curtain. The light curtain 1 of the present configuration example is a form of a multi-optical-axis photoelectric sensor, and generally includes a pair of a light projector 100 and a light receiver 200.

[0014] The light curtain 1 detects a person or an object by detecting whether at least one of a plurality of optical axes (six optical axes Oax1 to Oax6 in the present drawing) formed at intervals from each other is blocked, between the light projector 100 and the light receiver 200 arranged in parallel.

[0015] The light projector 100 and the light receiver 200 each include an elongated (more than 2 m in maximum) case 110 and 210, and cables 120 and 220 connected thereto.

[0016] The case 110 has a hollow metal case 111 extending in a longitudinal direction, and hollow end caps 112 and 113 (corresponding to end members) connected to both ends of the metal case 111, respectively. Similarly, the case 210 has a hollow metal case 211 extending in a longitudinal direction, and hollow end caps 212 and 213 (corresponding to end members) connected to both ends of the metal case 211, respectively. In the present embodiment, the longitudinal direction refers to a direction in which the plurality of optical axes formed between the light projector 100 and the light receiver 200 are arranged at intervals in a direction substantially parallel to each other.

[0017] Thus, by using the metal housings 111 and 211 having high rigidity as the outer shells of the housings 110 and 210, respectively, the elongated housings 110 and 210 are less likely to be deformed. Therefore, the arrangement adjustment (e.g., the angle adjustment for arranging the light projector 100 and the light receiver 200 in parallel) becomes relatively easy. In addition, the metal housings 111 and 211 can be formed of, for example, an aluminum extrusion product, which is inexpensive and light. In this case, the metal housings 111 and 211 are cut at any position in the extrusion direction (= the long side direction), and the cross sections thereof have the same shape.

[0018] The end covers 112, 113, 212, and 213 can be formed by injection molding using a resin material, or can be formed by die casting using a metal material such as zinc. In addition, the end covers 113 and 213 on the lower side in the drawing can be provided with interfaces with the cables 120 and 220. Therefore, the end covers 113 and 213 can be larger than the end covers 112 and 212 on the upper side in the drawing.

[0019] <Light Projector> Figure 2 and Figure 3 are a perspective view and a front view, respectively, showing the overall structure of the light projector 100. In addition, Figure 4 is a perspective view showing one end portion of the light projector 100.

[0020] As described above, the light projector 100 is provided with the housing 110 and the cable 120. In addition, the housing 110 has the metal housing 111 and the end covers 112 and 113. Further, the light projector 100 is provided with the front cover 130, the indicator lamp 140, and the buffer portion 150.

[0021] The front cover 130 is an elongated light-transmissive plate that covers the front opening portion (= the detection window) of the housing 110. In the front opening portion of the housing 110, the light projecting elements 161 to 166 that form the plurality of optical axes Oaxl to Oax6 are arranged at equal intervals in the long side direction. That is, the front cover 130 is attached to the housing 110 so as to intersect the plurality of optical axes Oaxl to Oax6. The front cover 130 can be a light-transmissive resin plate (e.g., an acrylic plate) formed by extrusion molding, or can be a glass plate. In the present embodiment, the light-transmissivity of the component used as the front cover 130 means the light-transmissivity at which the light of the light projecting elements 161 to 166 that form the plurality of optical axes Oaxl to Oax6 is not excessively diffused outside the optical axes, but is received by the light receiving elements 261 to 266 described later with a light amount of a certain degree or more. Since the front cover 130 uses such a light-transmissive component, an operator can see the light projecting elements 161 to 166 through the front cover 130.

[0022] In addition, in the end cover 113, it is preferable to arrange the light projecting element corresponding to at least one of the plurality of optical axes Oaxl to Oax6 (in the present embodiment, the light projecting element 161) in a position where the light projecting element 161 is not blocked by the end cover 113. In addition, in the end cover 213, it is preferable to arrange the light projecting element corresponding to at least one of the plurality of optical axes Oaxl to Oax6 (in the present embodiment, the light projecting element 161) in a position where the light projecting element 161 is not blocked by the end cover 213. Figure 3The light projecting elements 161 to 166 are preferably arranged at equal intervals along the entire region from one end to the other end of the light projector 100 in the longitudinal direction of the light projector 100. In addition, the cable 120 is preferably extended from the back surface (or side surface) of the end cover 113, rather than from the bottom surface of the end cover 113. With this structure, the light projector 100 can be installed very close to the installation surface (e.g., the floor). Thus, a dead space can be eliminated.

[0023] The indicator lamp 140 is turned on and off in a corresponding light emission color, for example, in accordance with the operation state (light axis detection state and self-diagnosis result, etc.) of the light curtain 1 or the work instruction related to the passage of the article, etc. In other words, the indicator lamp 140 functions as an operation indicator lamp or a work indicator lamp. Thus, the operator can visually recognize the operation state or the work instruction of the light curtain 1 by observing the indicator lamp 140 of the light curtain 1.

[0024] In particular, the indicator lamp 140 is arranged outside the outer surface of at least one of the front cover 130 and the housing 110 in the longitudinal direction, or is formed integrally with the front cover 130 (the details of the structure will be described later). According to the present drawing, the indicator lamp 140 is provided on both sides of the front cover 130. The indicator lamp 140 arranged or formed in this way can achieve a highly visible display without impairing the rigidity of the housing 110. More specifically, the indicator lamp 140 is an extrusion molded product, and the indicator lamp 140 is arranged in the longitudinal direction of the housing 110. Note that the indicator lamp 140 can be any structure arranged in the longitudinal direction of the housing 110, and the manufacturing method is not limited to extrusion molding, and the shape of the indicator lamp 140 is not necessarily elongated. For example, it can be a structure in which a plurality of components that function as the indicator lamp 140 are arranged in the longitudinal direction of the housing 110.

[0025] Further, the indicator lamp 140 is a light diffusion member that diffuses light incident from an indicator lamp light source 170 (not shown in the drawing) housed inside the housing 110 in various directions. More specifically, the indicator lamp 140 contains a light diffusion body that diffuses light in various directions. In a structure in which the indicator lamp 140 as a light diffusion member contains a light diffusion body, even if the indicator lamp light source 170 is small relative to the size of the surface of the indicator lamp 140, the indicator lamp 140 can be made to emit light relatively uniformly, and thus a display with high visibility can be achieved. In the present embodiment, the indicator lamp 140 is composed of a transparent resin to which microparticles are added, and thus appears milky white. When the resin that is the base is opaque and of a specific color, a color that is a mixture of the specific color and the milky white color appears. In addition to the structure in which the indicator lamp 140 contains a light diffusion body, the indicator lamp 140 can also be composed of a milky white resin (such as silicone resin or the like), and in this case as well, the effect of causing the indicator lamp 140 to emit light relatively uniformly can be obtained. The indicator lamp 140 as a light diffusion member can be a member that diffuses light from the indicator lamp light source 170 so as to be visible from more directions, or a member that diffuses light from the indicator lamp light source 170 to such a degree that the outline of the indicator lamp light source 170 is difficult to recognize from the outside of the indicator lamp 140. For example, a light diffusion member whose surface is processed to diffuse light from the indicator lamp light source 170 can be disposed as the indicator lamp 140. As surface processing that diffuses light, rough processing is known, for example. With a structure in which a light diffusion member whose surface is processed is disposed as the indicator lamp 140, when a region that diffuses light relatively easily and a region that diffuses light relatively difficultly are provided in one member, such a member can be manufactured more easily.

[0026] The buffer portions 150 are disposed on the outer surface of the front cover 130, protruding outside the region that intersects the plurality of optical axes Oaxl to Oax6, along the longitudinal direction of the housing 110 (the details of the structure will be described later).

[0027] According to the present drawing, the buffer portions 150 are formed in a pair protruding from both sides of the front cover 130. That is, the front cover 130 is installed in a narrow valley sandwiched by a pair of buffer portions 150 (double buffer proposed by the present applicant) that protrude forward from both sides. Therefore, even if an object strikes the front of the light projector 100, the impact is absorbed by the buffer portions 150. Therefore, the front cover 130 is not easily damaged. Further, the buffer portions 150 can also be formed of a hard material such as metal.

[0028] Further, the structure of the light receiver 200 is basically the same as that of the light projector 100. Therefore, in the description of the light projector 100, the light projector 100 and the light projecting elements 161 to 166 are replaced by the light receiver 200 and the light receiving elements 261 to 266, respectively, and the other 100-series symbols are appropriately replaced by 200-series symbols, and the structure of the light receiver 200 can be understood. The following description also applies equally. Figures 2 to 4 the light projector 100, the light projector 100 and the light projecting elements 161 to 166 are replaced by the light receiver 200 and the light receiving elements 261 to 266, respectively, and the other 100-series symbols are appropriately replaced by 200-series symbols, and the structure of the light receiver 200 can be understood. The following description also applies equally.

[0029] <Function Module> Figure 5 is a functional block diagram of the light curtain 1. In the light curtain 1 of the present configuration example, the light projector 100 is provided with the indicator lamp 140, the light projecting elements 161 to 166, the indicator lamp light source 170, the control circuit 181, and the communication circuit 182.

[0030] The light projecting elements 161 to 166 are arranged at regular intervals in the longitudinal direction of the light projector 100 at regular intervals. The light projecting elements 161 to 166 sequentially project a plurality of light beams that form a plurality of optical axes Oaxl to Oax6 in a time-division manner to the light receiver 200 (particularly, the light receiving elements 261 to 266) based on a light projecting control signal input from the control circuit 181. Further, the light projecting elements 161 to 166 can be, for example, infrared light emitting diodes.

[0031] The indicator lamp light source 170 supplies light for display to the indicator lamp 140 according to a display control signal input from the control circuit 181. The indicator lamp light source 170 can switch a plurality of light emission colors (for example, red, green, and orange) according to the operation state of the light curtain 1 or a job instruction, and the like.

[0032] Further, the indicator lamp light source 170 is preferably pulsed on at a timing that is offset in time from the light projecting / receiving timing of each of the plurality of optical axes Oaxl to Oax6. With this on / off control, interference with optical axis detection by the indicator lamp light source 170 can be suppressed.

[0033] The indicator lamp 140 diffuses light incident from the indicator lamp light source 170 in various directions. An operator can visually recognize the operation state of the light curtain 1 or a job instruction, and the like by observing the indicator lamp 140.

[0034] The control circuit 181 receives an instruction from the light receiver 200, generates a light projecting control signal to sequentially drive the light projecting elements 161 to 166 in a time-division manner. Further, the control circuit 181 generates a display control signal to pulse on and off the indicator lamp light source 170 in an arbitrary light emission color. In addition, the control circuit 181 exchanges various information with the communication circuit 182.

[0035] The communication circuit 182 performs wired or wireless communication with the light receiver 200 (particularly, the communication circuit 282). The communication circuit 182, for example, receives information input from the light receiver 200 regarding the operation state (optical axis detection state and self-diagnosis result, and the like) of the light curtain 1, and conveys it to the control circuit 181.

[0036] On the other hand, the light receiver 200 is provided with an indicator lamp 240, light receiving elements 261 to 266, an indicator lamp light source 270, a control circuit 281, a communication circuit 282, an output circuit 283, and an input circuit 284.

[0037] The light receiving elements 261 to 266 are arranged at equal intervals along the longitudinal direction of the light receiver 200 at the same intervals as the light projecting elements 161 to 166. The light receiving elements 261 to 266 sequentially receive a plurality of light beams forming a plurality of optical axes Oaxl to Oax6 in a time-division manner based on a light receiving control signal input from the control circuit 281. Further, the light receiving elements 261 to 266 can be photodiodes or phototransistors that output an electric signal according to the amount of received infrared light.

[0038] The indicator lamp light source 270 supplies light for display to the indicator lamp 240 based on a display control signal input from the control circuit 281. The indicator lamp light source 270 can be the same as the indicator lamp light source 170 and can switch a plurality of emission colors (for example, red, green, and orange) according to the operation state of the light curtain 1 or a job instruction.

[0039] Further, the indicator lamp light source 270 is preferably pulsed on at a timing that is shifted in time from the light projecting / receiving timing of each of the plurality of optical axes Oaxl to Oax6. By this on / off control, it is possible to suppress the interference of the indicator lamp light source 270 with the optical axis detection.

[0040] In addition, a case where the indicator lamp light source 270 is continuously on is considered. In this case, even if the direct current light emitted from the indicator lamp light source 270 is received by the light receiving elements 261 to 266, in order to prevent the saturation of the electric signal output from the light receiving elements 261 to 266, a saturation prevention circuit (i.e., a direct current component subtraction circuit) is preferably provided.

[0041] The indicator lamp 240 diffuses the light incident from the indicator lamp light source 270 in various directions. By observing the indicator lamp 240, the operator can visually recognize the operation state of the light curtain 1 or a job instruction.

[0042] In addition, since the indicator lamps 140 and 240 are respectively provided on both the light projector 100 and the light receiver 200, it is possible to perform display with high visibility.

[0043] The control circuit 281 generates a light receiving control signal to sequentially activate the light receiving elements 261 to 266 in a time-division manner in synchronization with the drive timing of each of the light projecting elements 161 to 166. Further, the control circuit 281 generates a display control signal to turn on and off the indicator lamp light source 270 in an arbitrary emission color. In addition, the control circuit 281 exchanges various information with the communication circuit 282, the output circuit 283, and the input circuit 284.

[0044] Furthermore, the control circuit 281 monitors the light-receiving / light-blocking state of each of the multiple optical axes Oax1 to Oax6. For example, when all of the multiple optical axes Oax1 to Oax6 are in the light-receiving state, the control circuit 281 can output an operation permission signal (ON signal). On the other hand, when at least one of the multiple optical axes Oax1 to Oax6 is in the light-blocking state, the control circuit 281 can output an operation disallowance signal (OFF signal).

[0045] Furthermore, the control circuit 281 may have a self-diagnostic function to determine whether it is in a state capable of correctly monitoring the light-receiving / light-blocking state of each of the multiple optical axes Oax1 to Oax6. As a self-diagnostic method, for example, the control circuit 281 and the output circuit 283 (e.g., OSSD [Output Signal Switching Device] output) may be multiplexed, and then the consistency / inconsistency of the multiplexed signals may be determined.

[0046] For example, if the multiplexed signals are consistent, an OK diagnosis will be given (meaning the status can be monitored correctly). On the other hand, if the multiplexed signals are inconsistent, an NG diagnosis will be given (meaning the status cannot be monitored correctly). Furthermore, in the case of an NG diagnosis, an OFF signal can be output, regardless of the light-receiving status of each of the multiple optical axes Oax1 to Oax6.

[0047] Furthermore, information that can be used for safety control is called safety information, while general information that cannot be used for safety control is called non-safety information. For example, OSSD output is one type of safety information. Signals used to control the lighting and extinguishing of indicator lights 170 and 270 can be either signals indicating safety information or signals indicating non-safety information.

[0048] The communication circuit 282 communicates with the projector 100 via wired or wireless communication (specifically, the communication circuit 182). For example, the communication circuit 282 receives information input from the control circuit 281 regarding the operating status of the light curtain 1 (optical axis detection status and self-diagnostic results, etc.) and transmits it to the projector 100.

[0049] The output circuit 283 communicates with external devices (such as a safety controller) via wired or wireless communication. For example, the output circuit 283 receives input from the control circuit 281 regarding the operating status of the light curtain 1 (optical axis detection status and self-diagnostic results, etc.) and transmits it to the external device.

[0050] The input circuit 284 communicates with external devices (such as safety controllers) via wired or wireless communication. For example, the input circuit 284 receives operation instructions from external devices regarding the entry and exit of items and transmits them to the control circuit 281.

[0051] <First Implementation> Figure 6 This is a diagram showing a first embodiment of the projector 100 (a schematic cross-sectional view of the metal casing 111 of the projector 100 cut at any position along its long side). The projector 100 of this embodiment includes a housing 110 (only the metal casing 111 is depicted in this figure), a front cover 130, an indicator light 140, a buffer section 150, an indicator light source 170, a substrate 190, and a light shield 191.

[0052] The metal casing 111 is an extruded product extending along the long side of the projector 100. As shown in this figure, the metal casing 111 consists of a body 111a, a pair of first protruding strips 111b, and a pair of second protruding strips 111c.

[0053] The main body 111a is a hollow U-shaped component with an opening on the paper surface (i.e., the front side of the projector 100). The internal space of the main body 111a houses the indicator light source 170, the substrate 190, and the light shield 191.

[0054] A pair of first protruding strips 111b protrude from the inner surfaces of the left and right side walls of the main body 111a toward the inside of the opening. That is, the pair of first protruding strips 111b sandwich the optical axis intersection region X (the region intersecting with multiple optical axes Oax1 to Oax6) and are arranged opposite each other at a certain interval. Furthermore, the pair of first protruding strips 111b function as a cover mounting portion supporting the front cover 130. As described above, the front cover 130 uses a light-transmitting material, but it is sufficient that at least the optical axis intersection region X is light-transmitting and does not obstruct the structure of the optical axes Oax1 to Oax6. For example, in this embodiment, the portion in contact with the pair of first protruding strips 111b does not necessarily need to be light-transmitting.

[0055] A pair of second protruding strips 111c extend further upwards from the upper ends of the left and right side walls of the main body 111a, respectively. Furthermore, the front ends of each pair of second protruding strips 111c curve inwards towards the opening. Additionally, the pair of second protruding strips 111c function as a buffer portion 150 to protect the front cover 130. That is, in this embodiment, the buffer portion 150 is formed by a metal casing 111. Therefore, the robustness of the projector 100 can be improved.

[0056] The front cover 130 is supported (suspended) at both ends by spanning a pair of first protruding strips 111b. The front cover 130 allows light forming multiple optical axes Oax1 to Oax6 to pass through in the optical axis intersection region X. A treatment to improve liquid resistance is performed between the front cover 130 and the pair of first protruding strips 111b (see thick line α). For example, a sealing gasket is placed, and the strips are bonded with a liquid-resistant adhesive. As described later, the liquid resistance is further improved because the indicator light 140 enhances the seal between the front cover 130 and the first protruding strips 111b.

[0057] Indicator light 140 is arranged near the buffer portion 150, on both sides of the front cover 130. As shown in this figure, indicator light 140 is arranged in the area between the front ends (bent portions) of the first protrusion 111b and the second protrusion 111c, that is, in the area sandwiched between the buffer portion 150 and the front cover 130, along the long side of the projector 100.

[0058] Furthermore, the indicator light 140 can diffuse light incident from the indicator light source 170 through the front cover 130 in various directions. For example, the indicator light 140 can have a conical structure for refracting and diffusing light incident from the indicator light source 170 into the inside of the opening.

[0059] The indicator lights 140, arranged in this way, are easily visible even from the side of the projector 100. Therefore, in a small (narrow diameter) light screen 1 using a metal housing 111, highly visible displays can be achieved without compromising the rigidity of the housing 110. In particular, the improved visibility effect brought about by the above arrangement may be even more significant when a pair of buffer portions 150 are provided protruding on both sides of the front cover 130.

[0060] Furthermore, in the projector 100 of this embodiment, the indicator light 140 also functions as a clamping member that presses and fixes the front cover 130 downwards (towards the first protruding strip 111b). Therefore, since the sealing between the front cover 130 and the first protruding strip 111b is improved, liquid intrusion into the interior of the metal casing 111 can be prevented, thereby improving liquid resistance. It should be noted that, in order for the indicator light 140 to function as a clamping member, the indicator light 140 preferably has appropriate elasticity.

[0061] The indicator light source 170 is mounted on the main surface of the substrate 190 (the surface opposite to the front cover 130). The indicator light source 170 provides light for displaying to the indicator light 140 through the front cover 130. As shown in this figure, the light emitted from the indicator light source 170 is not blocked by a pair of first protruding strips 111b, but passes between the pair of first protruding strips 111b and is supplied to the indicator light 140 through the front cover 130.

[0062] Furthermore, the number of indicator light sources 170 is not limited. For example, multiple indicator light sources 170 can be arranged intermittently along the long side of the projector 100, or they can be integrated into one unit.

[0063] Furthermore, the indicator light source 170 can be equipped with a lens for controlling the direction of emitted light. For example, an optically designed lens can be provided that reduces the light diffusion angle in the left-right direction of the image while increasing the light diffusion angle in the depth direction of the image. With such a lens, the number of indicator light sources 170 can be reduced while suppressing interference with multiple optical axes Oax1 to Oax6.

[0064] In addition, the lens can be either a point-symmetric lens (configured separately) or a cylindrical lens (configured as an integral part of an extruded product).

[0065] A light shield 191 is disposed between the indicator light source 170 and the optical axis intersection region X. Therefore, since the light from the indicator light source 170 toward the optical axis intersection region X is blocked, the light emitted from the indicator light source 170 is less likely to interfere with multiple optical axes Oax1 to Oax6.

[0066] Furthermore, consider the case where optical axes Oax1 to Oax6 are formed by infrared light, and visible light (such as red, green, or orange light) is emitted from the indicator light source 170. In this case, a filter that transmits infrared light while blocking visible light can be provided on the light receiver 200. In particular, when the light receiver 200 is equipped with an indicator light 240, in order not to obstruct the display of the indicator light 240, it is sufficient to adopt a structure that arranges a filter that transmits infrared light while blocking visible light. The filter can be provided on the light receiving elements 261 to 266, or it can be provided on the lens that guides the light to the light receiving elements 261 to 266.

[0067] Figure 7 This figure shows an example of the configuration of the indicator light source 170 in the first embodiment. As shown in this figure, the light-emitting elements 161 to 166 can be arranged at equal intervals along the long side direction of the substrate 190 in the central region 190a of the substrate 190. On the other hand, the indicator light source 170 can be arranged at equal intervals along the long side direction of the substrate 190 in the end region 190b of the substrate 190.

[0068] In particular, the light-emitting elements 161-166 and the indicator light source 170 can be configured to be staggered (interleaved) in the long side direction of the substrate 190. This arrangement example can suppress mutual interference between the light-emitting elements 161-166 and the indicator light source 170.

[0069] Furthermore, the number and configuration of the indicator light sources 170 are not limited to the configuration example shown in this figure. For example, the number of indicator light sources 170 may be reduced to result in some non-uniformity in the light supplied to the indicator lights 140.

[0070] <Function Extension> Figure 8 This is a comparison diagram showing the relationship between the presence or absence of functional expansion of light curtain 1 and the installation components, comparing the old and new versions. The upper part of this diagram depicts the old structure of light curtain 1. On the other hand, the lower part of this diagram depicts the new structure of light curtain 1. In this diagram, the long side direction of light curtain 1 is set as the x-axis, the short side direction as the y-axis, and the thickness direction (depth direction) as the z-axis.

[0071] The light curtain 1 in this figure can be understood as the projector 100 mentioned above. However, in the following description, if the symbol of the 100 series is replaced with the symbol of the 200 series, the light curtain 1 in this figure can also be understood as the receiver 200.

[0072] It should be noted that in the upper and lower sections of this diagram, the left column represents the case without functional expansion, the middle column represents the case with the series connection cable 4 connected, and the right column represents the case with the operation indicator light 5 connected. The series connection cable 4 and the operation indicator light 5 are respectively installed on the end cap 112 of the light curtain 1, and can be understood as functional expansion components that extend the functionality of the light curtain 1. The series connection cable 4 is used to connect the light curtain 1 in series with other light curtains. The operation indicator light 5 is used to display the operating status of the light curtain 1. Thus, through the light curtain 1 and its various installable and detachable functional expansion components, a multi-axis photoelectric sensor with functional expandability is constructed.

[0073] Mounting components 2 and 2a-2e are respectively equivalent to tooling for mounting the light curtain 1 onto the base 3. That is to say, a multi-axis photoelectric sensor with mounting components 2 and 2a-2e and the light curtain 1 mounted on mounting components 2 and 2a-2e can be installed on the base 3.

[0074] Furthermore, as shown in the upper part of the figure, the light curtain 1 of the old structure is mounted on the base 3 via a common mounting bracket 2, regardless of whether the series connection cable 4 and the operation indicator light 5 are connected. The mounting bracket 2 is designed to minimize the gap between the light curtain 1 and the base 3. Therefore, the light curtain 1 of the old structure is designed not to protrude the series connection cable 4 and the operation indicator light 5 from the outer peripheral surface opposite to the base 3, such as the back. According to this figure, the back of the end cap 112 ensures extra space equivalent to the thickness of the series connection cable 4 or the operation indicator light 5. Therefore, there are limitations to miniaturizing the housing 110 of the light curtain 1 of the old structure.

[0075] On the other hand, as shown in the lower part of the figure, the new structure of the light curtain 1 does not take into account the thickness of the series connection cable 4 and the operation indicator light 5 that may be connected when the function is expanded. Instead, it takes the standalone use of the light curtain 1 as a premise and minimizes the size of the housing 110. In other words, the design of the new structure of the light curtain 1 allows the series connection cable 4 and the operation indicator light 5 to protrude from the back of the light curtain 1 when the function is expanded.

[0076] For example, the series connection cable 4 and the operation indicator light 5 each have protrusions 4a and 5a, respectively. The protrusions 4a and 5a extend along the long side of the light curtain 1 and protrude from the back of the light curtain toward the base 3, and are mounted on the end cap 112 of the light curtain 1.

[0077] As a result, the size of the gap between the light curtain 1 and the base 3 in the new structure will change depending on whether the function is expanded. Therefore, as a tooling for mounting the light curtain 1 of the new structure onto the base 3, it is best to prepare various types of mounting parts 2a to 2e depending on whether the function is expanded.

[0078] Mounting member 2a has a base portion a1. The base portion a1, for example, is mounted on the back of the base 3 and accommodates the housing 110 of the light curtain 1 from the front. Mounting member 2a is used when the light curtain 1 is used alone. Therefore, mounting member 2a can be configured like mounting member 2 described above to minimize gaps between the light curtain 1 and the base 3. Specifically, the thickness of the base portion a1 between the light curtain 1 and the base 3 can be designed to the necessary minimum.

[0079] Mounting member 2b is an L-shaped angle steel with main surfaces b1 and b2. Main surface b1 can be the xy-plane mounted on the base 3. Main surface b2 can be the yz-plane mounted on the end face of the end cap 112 along the long side of the light curtain 1. Mounting member 2a is used when the light curtain 1 is used alone. Therefore, mounting member 2a, like mounting member 2 described above, can be configured to minimize gaps between the light curtain 1 and the base 3. Specifically, the z-axis length of the main surface b2 can be designed based on the z-axis thickness of the light curtain 1.

[0080] Thus, when the light curtain 1 is used alone, mounting components 2a and 2b, which are smaller in the thickness direction than the mounting components 2c to 2e described later, can be used. Therefore, by miniaturizing the light curtain 1 and the mounting components 2a and 2b, space-saving installation of the multi-axis photoelectric sensor as a whole can be achieved.

[0081] Mounting member 2c has a base portion c1. The base portion c1, for example, is mounted on the base 3 from the back and accommodates the housing 110 of the light curtain 1 from the front. Mounting member 2c is used for connecting the cable 4 in series. Therefore, mounting member 2c can be configured to form a receiving space for accommodating the protrusion 4a between the back of the light curtain 1 and the base 3. Specifically, the thickness of the base portion c1 can be designed such that the distance from the back of the light curtain 1 to the back of the base portion c1 is greater than the thickness of the protrusion 4a.

[0082] Mounting member 2d is an L-shaped angle steel with main surfaces d1 and d2. Main surface d1 can be the xy-plane mounted on the base 3. Main surface d2 can be the yz-plane mounted on the end face of the upper cover 112 along the long side of the light curtain 1. Mounting member 2d is used for connecting the cable 4 in series. Therefore, mounting member 2d can be configured to form a receiving space for the protrusion 4a between the back surface of the light curtain 1 and the base 3. Specifically, the length of the main surface b2 in the z-axis direction can be designed such that the distance from the back surface of the light curtain 1 to the main surface d1 is greater than the thickness of the protrusion 4a.

[0083] Mounting member 2e has a base portion e1. The base portion e1, for example, is mounted on the back of a base 3 and accommodates the housing 110 of the light curtain 1 from the front. Mounting member 2e is used to connect the operation indicator light 5. Therefore, mounting member 2e can be configured to form a receiving space between the back of the light curtain 1 and the base 3 for accommodating the protrusion 5a. Specifically, the thickness of the base portion e1 can be designed such that the distance from the back of the light curtain 1 to the back of the base portion e1 is greater than the thickness of the protrusion 5a.

[0084] Thus, when the function of the light curtain 1 is expanded, mounting members 2c to 2e that can absorb the thickness of the protrusions 4a and 5a can be used. Therefore, even if the protrusions 4a and 5a protrude from the back of the light curtain 1 toward the base 3, they will not easily cause obstacles to the installation of the light curtain 1.

[0085] It should be noted that this diagram is for illustrative purposes only. Referring to this diagram, in addition to the light curtain and its various installable and detachable functional expansion components, it also includes various types of mounting hardware. Through a series of product developments, a wide variety of user needs can be flexibly addressed.

[0086] Figure 9 This figure illustrates the relationship between the functional expansion of light curtain 1 and its thickness (depth direction) dimensions. The upper part of the figure depicts the side of light curtain 1. On the other hand, the lower part of the figure depicts the cross-section of light curtain 1 when cut perpendicular to the y-axis, i.e., the zx section.

[0087] The light curtain 1 is composed of a metal housing 111, an end cap 112, and a substrate 190. The metal housing 111 can be understood as the main body of the light curtain 1 in which multiple optical axes are formed along its long side. The end cap 112 can be understood as an end component fixed to one end of the metal housing 111. The substrate 190 is disposed in the range from the metal housing 111 to the end cap 112. Optical elements forming multiple optical axes and their control circuits are mounted on the substrate 190. Multiple optical elements are arranged on the substrate 190 at predetermined intervals along its long side. The multiple optical axes are formed not only in the metal housing 111 but also in the end cap 112. The substrate 190 can be divided into multiple parts along its long side.

[0088] As shown in the upper and right columns of this figure, the series connection cable 4 and the operation indicator light 5 are respectively installed to the back of the end cover 112 from a direction perpendicular to the long side of the light curtain 1, i.e., the z-axis direction. At this time, protrusions 4a and 5a protrude from the back of the light curtain 1. Electrical components, electrical wiring, and substrates can be accommodated in protrusions 4a and 5a.

[0089] The operation indicator light 5, for example, has a light-emitting part 5x, a bottom part 5y, and a connecting part 5z. The light-emitting part 5x emits light to indicate the operating status of the light curtain 1. The light-emitting part 5x can be dome-shaped. The bottom part 5y abuts against the end face of the end cover 112 along the long side of the light curtain 1 and supports the light-emitting part 5x. The bottom part 5y can be fastened to the end cover 112 with screws or the like. This improves the dustproof and waterproof performance of the light curtain 1. The connecting part 5z extends from the bottom part 5y along the long side of the light curtain 1 to the back of the end cover 112.

[0090] On the other hand, as shown in the left column of the figure, when the series connection cable 4 and the operation indicator light 5, and other functional expansion components, are not installed, that is, when the light curtain 1 is used alone, the terminal cover 112x is installed on the back of the end cover 112. The terminal cover 112x can be formed to remain flush with the back of the light curtain 1 without protruding from it.

[0091] The terminal cover 112x, the series connection cable 4, and the operation indicator light 5 are directly connected to the base plate 190 via a connector 301 mounted on the light curtain 1. This structure allows for miniaturization of the housing 110 compared to conventional structures that also include a separate sub-board for functional expansion.

[0092] Figure 10 The mounting mechanism of the end cap 112 is shown. The top section of this figure depicts the back of the light curtain 1. The bottom three sections of this figure depict the mounting surfaces of the end cap 112x, the series connection cable 4, and the operation indicator light 5, which are the surfaces opposite to the end cap 112 when mounted on the light curtain 1.

[0093] The light curtain 1 has a connector 301. The connector 301 is mounted on a substrate 190 extending to an end cap 112. The connector 301 can be configured on the substrate 190 in the opposite direction to the light projection direction or the light receiving direction of the optical element, i.e., on the back side of the end cap 112.

[0094] The end cap 112 has an opening 112y on its rear side that exposes the connector 301. Therefore, the connector 301 can be detachably mounted with various functional expansion components from a direction perpendicular to the long side of the light curtain 1, i.e., the z-axis direction. For example, the connector 301 can selectively mount any one of the end cap 112x, the series connection cable 4, and the operation indicator light 5.

[0095] When neither the series connection cable 4 nor the operation indicator 5 is installed, the terminal cover 112x is mounted on the connector 301. The terminal cover 112x can be understood as a cover component used to cover the opening 112y of the end cover 112 when the light curtain 1 is used alone. However, the terminal cover 112x is not just a simple cover component, but also has the function of enabling the light curtain 1 to recognize itself as a terminal.

[0096] The terminal cover 112x, the series connection cable 4, and the operation indicator light 5 each have connectors 311, 321, and 331 that can be installed and removed from connector 301. When the terminal cover 112x is installed on the end cover 112, connector 301 connects to connector 311. When the series connection cable 4 is installed on the end cover 112, connector 301 connects to connector 321. When the operation indicator light 5 is installed on the end cover 112, connector 301 connects to connector 331.

[0097] In addition, the light curtain 1 has a guide section 302. The guide section 302 guides connectors 311, 321, and 331 to their respective connection positions with connector 301. The guide section 302 may be a rectangular frame-like component surrounding connector 301. The guide section 302 may be designed with a height slightly greater than that of connector 301 in the z-axis direction.

[0098] For example, when end cap 112x is installed on end cap 112, end cap 112x is first positioned by the guide part 302, and then connector 301 and connector 311 are connected.

[0099] The same applies when the series connection cable 4 or the operation indicator 5 is installed on the end cover 112. That is, after the series connection cable 4 or the operation indicator 5 is positioned relative to the end cover 112, the connector 301 is connected to the connector 321 or 331.

[0100] With this structure, even if the relative positions are offset, the connectors are unlikely to make contact with each other. Therefore, damage to connector 301, as well as connectors 311, 321, and 331, can be prevented.

[0101] The terminal cover 112x, the series connection cable 4, and the operation indicator light 5 can be fastened to the terminal cover 112 with screws or the like. This structure can improve the dustproof and waterproof performance of the light curtain 1.

[0102] The guide portion 302 is preferably fixed to the end cap 112 without contacting the substrate 190. This structure reduces the load applied to the substrate 190 when the connector 301 is connected to connectors 311, 321, or 331. Therefore, the substrate 190 is less prone to deformation, thus minimizing its impact on the optical axis.

[0103] The terminal cover 112x may have a guide portion 312 for guiding connector 311 to the connection position with connector 301. The serial connection cable 4 may have a guide portion 322 for guiding connector 321 to the connection position with connector 301. The operation indicator light 5 may have a guide portion 332 for guiding connector 331 to the connection position with connector 301. With this structure, damage caused by accidental contact between connectors can be prevented. However, if the light curtain 1 is provided with guide portion 302, then guide portions 312, 322, and 332 are not necessary.

[0104] The terminal cover 112x, the series connection cable 4, and the operation indicator light 5 each have sealing gaskets 313, 323, and 333, respectively. When the terminal cover 112x is installed on the end cover 112, the area around the opening 112y is sealed by the sealing gasket 313. When the series connection cable 4 is installed on the end cover 112, the area around the opening 112y is sealed by the sealing gasket 323. When the operation indicator light 5 is installed on the end cover 112, the area around the opening 112y is sealed by the sealing gasket 333.

[0105] The terminal cover 112x and the operation indicator 5 are equipped with DIP switches 314 and 334, respectively. DIP switches 314 and 334 can be used as interference prevention setting switches. For example, by using the 2-bit 4-value DIP switches 314 and 334, settings such as "00 (interference prevention setting off)," "01 (setting A)," and "10 (setting B)" can be made. By making such interference prevention settings, erroneous synchronization or malfunction between adjacent light curtains can be prevented.

[0106] <Cable Connection> Figure 11This is a comparison diagram of the old and new cable connection structures in light curtain 1. The left column of this diagram depicts the old structure (connector connection type). The right column depicts the new structure (direct lead-out type). As shown in this diagram, the end cap 113 of light curtain 1 is connected to the cable 120. The end cap 113 is located at both ends of light curtain 1, opposite to the end cap 112, which allows for the installation and removal of the series connection cable 4 or the operation indicator light 5, etc.

[0107] In the older design, cable 120 can be installed and removed from end cap 113 via connector 121. Therefore, the number of pins on cable 120 can be changed arbitrarily according to user requirements. However, in the older design, connector 121 protrudes from the back of light curtain 1. This may hinder space-saving installation. For example, refer to the above... Figure 8 To illustrate, when the light curtain 1 is used alone, it may be difficult to install it onto the base 3 using mounting parts 2a and 2b.

[0108] In view of the above considerations, in the new structure, the cable 120 does not protrude from the outer peripheral surface of the light curtain 1, but is led out directly from the end cap 113 along the long side of the light curtain 1. Therefore, space-saving installation can be achieved more easily.

[0109] Furthermore, cable 120 can be a so-called pigtail cable. That is, the end of cable 120 can be equipped with connector 122. Connector 122 can be a highly versatile M12 connector. With this structure, the number of pins of the detachable cable (not shown in the figure) connected to the front end of connector 122 can be arbitrarily changed according to user needs. In addition, for example, the function and operation of light curtain 1 can be switched according to the number of pins of the detachable cable connected to connector 122, such as enabling / disabling the communication function.

[0110] Figure 12 This is a cross-sectional view showing an example of a cable connection with the new structure (direct lead-out type). In particular, this figure can be understood as a cross-section when the light curtain 1 is cut perpendicularly to the y-axis, i.e., the zx section.

[0111] As shown in the figure, cable 120 can be directly connected to substrate 190 via crimp connector 123. Alternatively, cable 120 and substrate 190 can also be directly connected by soldering.

[0112] <End Cap Fixing> Next, refer to Figure 13 and Figure 14 A method for fixing the end cap 113 is proposed. Figure 13 This is a cross-sectional view showing an example of the fixing structure between the metal housing 111 and the end cap 113. Figure 13 This can be understood as the zx cross-section when light curtain 1 is cut perpendicularly to the y-axis. More specifically, it can be understood as... Figure 14 γ-γ profile.Figure 14 This shows the bottom surface of light screen 1. Figure 13 Diagrams of the α-α and β-β sections.

[0113] The light curtain 1 includes a housing 110, a front cover 130, a substrate 190, screws 340, an AC discharge section 350, and sealing gaskets 361 and 362. The housing 110 has a metal outer shell 111 and an end cap 113.

[0114] The metal casing 111 is a hollow component extending along the long side of the light curtain 1. The surface of the metal casing 111 is treated with insulating processes such as coating and anodizing.

[0115] The metal casing 111 contains a plurality of projection elements 160 forming optical axes Oax along the long side of the light curtain 1. The projection elements 160 can be understood as optical elements equivalent to the aforementioned projection elements 161 to 166.

[0116] A portion of the metal casing 111 can function as a buffer 150. The buffer 150 can protrude along multiple optical axes Oax from the outer surface of the front cover 130. This structure improves the robustness of the light curtain 1.

[0117] A threaded hole 111d is formed in the metal housing 111 to receive the tip of the screw 340. The threaded hole 111d can be formed as a through hole extending from one end face of the metal housing 111 to the other end face along the long side direction of the light curtain 1. The threaded hole 111d has a first region 111d1 and a second region 111d2. Figure 14 As shown in the α-α section and β-β section, the threaded holes 111d can be set in pairs on both sides of the optical axis Oax.

[0118] The first region 111d1 is the area within the threaded hole 111d near the end face of the metal housing 111; specifically, it can be understood as the area near the opposing surface of the end cap 113. The first region 111d1 may have a threaded groove that engages with the thread engraved on the front end of the screw 340. The first region 111d1 is not subjected to any insulating treatments such as painting or anodizing. Therefore, the metal housing 111 can establish an electrical connection with the screw 340 within the first region 111d1 of the threaded hole 111d.

[0119] The second region 111d2 can be understood as the region in the threaded hole 111d excluding the first region 111d1. The second region 111d2 can open towards the substrate 190 and can serve as a stop groove to support the stop protrusion 371 of the support 370 that carries the substrate 190. In other words, the metal housing 111 can have a pair of stop grooves on both sides of the support 370.

[0120] The bracket 370 has a pair of stop protrusions 371. The pair of stop protrusions 371 are respectively embedded in and supported in the stop grooves provided on the metal housing 111, that is, the second region 111d2 of the threaded hole 111d.

[0121] Each of the pair of stop protrusions 371 may have a position adjustment mechanism 372. The pair of position adjustment mechanisms 372 may be elastic components that apply pressure in the y-axis direction and the z-axis direction to the inner wall of the stop groove provided on the metal housing 111, i.e., the inner wall of the second region 111d2. Using this structure, the relative position of the substrate 190 with respect to the metal housing 111 in the y-axis direction and the z-axis direction can be adjusted respectively.

[0122] End cap 113 can be understood as an end component fixed to one end of metal housing 111. A through hole 113a is formed in end cap 113 for screw 340 to pass through. The through hole 113a extends from one end face of end cap 113 to the other end face along the long side of light curtain 1. Furthermore, cable 120 can also be connected to end cap 113.

[0123] The front cover 130 transmits light from the projection element 160 and is mounted on the front of the housing 110 in a manner that intersects with multiple optical axes Oax.

[0124] The substrate 190 is disposed within the enclosed space CS formed by the housing 110 and the front cover 130. The substrate 190 is equipped with a light-emitting element 160 and an AC discharge section 350.

[0125] The screw 340 can be understood as a fastener that secures the end cap 113 to the metal housing 111. The end cap 113 can be secured to the metal housing 111 by a pair of screws 340 inserted from the bottom side. The screws 340 can be conductive fasteners that are electrically connected to the metal housing 111.

[0126] The AC discharge unit 350 uses a conductive screw 340 to capacitively couple the metal casing 111 to the grounding wire 192 of the substrate 190. Therefore, the noise immunity of the light curtain 1 is improved. Furthermore, the AC discharge unit 350 will be described in detail later.

[0127] The sealing gasket 361 is sandwiched between the metal housing 111 and the end cap 113 to prevent external dust and liquid from entering the sealed space CS. The screw 340 is preferably located inside the sealing gasket 361, i.e., in the sealed space CS.

[0128] The sealing gasket 362 is sandwiched between the seat of the screw 340 and the end cap 113 to prevent external dust and liquid from entering the enclosed space CS.

[0129] <Alternating Current Discharge Section> Figure 15This is a diagram showing an example configuration of the AC discharge section 350. The AC discharge section 350 of this example configuration includes a capacitor 351 and a conducting member 352.

[0130] Capacitor 351 is mounted on substrate 190. The first end of capacitor 351 is connected to ground wire 192 provided on substrate 190. The second end of capacitor 351 is connected to conductive member 352 through wiring provided on substrate.

[0131] The conductive component 352 abuts against the screw 340, thereby establishing electrical connection between the second end of the capacitor 351 and the screw 340. The conductive component 352 will be described in detail later.

[0132] As previously described, screw 340 is electrically connected to metal housing 111. More specifically, screw 340, for example, is made of metal and is electrically connected to metal housing 111 by fastening it into an uninsulated threaded hole 111d. Metal housing 111 can be understood as grounded.

[0133] Through the aforementioned integrated electrical connection, capacitive coupling between the metal casing 111 and the grounding wire 192 is achieved using a conductive screw 340. Therefore, AC signals such as noise are discharged from the grounding wire 192 to the metal casing 111, thereby improving the noise immunity of the light curtain 1.

[0134] Furthermore, compared with the conventional structure that achieves electrical connection through the cut end face of the metal casing 111, this structure not only enables the miniaturization of the metal casing 111, but also makes it easier to ensure stable conduction.

[0135] Figure 16 This figure shows one configuration example of the conductive member 352. As shown in this figure, the conductive member 352 may be a conductive leaf spring, a so-called shielding finger, which abuts against the screw 340 in the through hole 113a of the insertion end cap 113 when under stress.

[0136] In addition, although not illustrated again, the fixing structure of the metal casing 111 and the end cap 112 is basically the same as described above.

[0137] <Outer shell shape> Figure 17 This is a cross-sectional view showing the shape of the housing 110 (particularly the metal outer shell 111). It should be noted that this figure depicts a cross-section of the housing 110 when it is cut perpendicularly at any point along its long side, i.e., a section perpendicular to the long side. As shown in this figure, the housing 110 has sidewall portions Pa and Pb, and arcuate portions Pc to Pf.

[0138] Sidewall portions Pa and Pb are approximately parallel to the optical axis Oax in the zy-section view of the housing 110. Sidewall portions Pa and Pb are arranged linearly symmetrically with respect to the optical axis Oax. Arc portions Pc to Pf each form part of a circle C in the zy-section view of the housing 110. Arc portions Pc and Pd are arranged linearly symmetrically with respect to the optical axis Oax. Arc portions Pe and Pf are arranged linearly symmetrically with respect to the optical axis Oax. Arc portions Pc and Pd are respectively located in front of sidewall portions Pa and Pb, i.e., on the surface side of the housing 110. Arc portions Pe and Pf are respectively located behind sidewall portions Pa and Pb, i.e., on the rear side of the housing 110.

[0139] The housing 110 in this structural example can be directly... Figure 8 The mounting is performed by gripping with mounting parts 2a, 2c, or 2e. Therefore, it is no longer necessary to form a metal mounting groove on the back side of the housing 110. Furthermore, in a general structure where a metal mounting groove is formed on the housing 110, the strength of the back portion forming the metal mounting groove must be increased, leading to a larger housing 110. Conversely, the housing 110 in this structural example is no longer limited by the strength of the back portion, thus enabling a smaller housing 110.

[0140] Furthermore, as described above, the housing 110 of this configuration example has arcuate portions Pc to Pf. Therefore, when the housing 110 is temporarily fixed to the mounting members 2a, 2c, or 2e, the rotational position of the housing 110 can be arbitrarily adjusted by rotating the housing 110 about the x-axis.

[0141] <Other variations> Furthermore, the various technical features disclosed in this specification, in addition to the embodiments described above, can be modified in various ways without departing from the spirit of the invention. In other words, the embodiments described above should be considered exemplary rather than restrictive in all respects, and the scope of the invention should be defined by the claims, which should be understood to include all modifications with equivalent meaning and scope to the claims.

Claims

1. A light curtain, comprising: The housing has a metal outer shell extending along its long side and an end member fixed to one end of the metal outer shell. Inside the housing is an optical element, one of a pair of light-emitting elements and a light-receiving element that forms multiple optical axes along the long side. A cover that transmits light emitted by the light-projecting element and is mounted on the housing in a manner that intersects with the plurality of optical axes; A substrate, which is disposed within a sealed space formed by the housing and the cover, and on which the optical element of one of the components is mounted; A conductive fastener that secures the end component to the metal housing and is electrically connected to the metal housing; The AC discharge section uses the fixing member to capacitively couple the metal casing to the grounding wire of the substrate.

2. The light curtain according to claim 1, wherein, The AC discharge section includes a capacitor mounted on the substrate with its first end connected to the grounding wire, and a conductive component that connects the second end of the capacitor to the fixing member.

3. The light curtain according to claim 2, wherein, The conductive component has a conductive leaf spring that abuts against the fixing member when a force is applied to the fixing member.

4. The light curtain according to any one of claims 1 to 3, wherein, The device includes a first sealing gasket sandwiched between the metal housing and the end component to prevent dust and liquid from entering the sealed space from the outside. The fastener is located inside the first sealing gasket.

5. The light curtain according to claim 4, wherein, The fastener is a screw, and a threaded hole for receiving the screw is formed in the metal housing.

6. The light curtain according to claim 5, wherein, The threaded hole is formed as a through hole extending from one end face of the metal casing to the other end face along the long side direction.

7. The light curtain according to claim 6, wherein, The first region of the through hole has a groove that is threaded to the screw, and the second region of the through hole opens toward the substrate, serving as a stop groove for supporting the stop protrusion of the bracket that carries the substrate.

8. The light curtain according to claim 7, wherein, The metal housing is provided with a pair of stop grooves that clamp the bracket, and the bracket is provided with a pair of stop protrusions that are respectively supported by the pair of stop grooves. The pair of stop protrusions have a position adjustment mechanism that adjusts the relative position of the substrate with respect to the metal housing by pressing the inner walls of the pair of stop grooves respectively.

9. The light curtain according to claim 5, wherein, It also includes a second sealing gasket sandwiched between the seat of the screw and the end member to prevent dust and liquid from entering the sealed space from the outside.

10. The light curtain according to claim 1, wherein, It has a buffer portion that protrudes along a plurality of optical axes from the outer surface of the cover.

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