Light Curtain

Abstract

To miniaturize the light curtain while maintaining dustproof and waterproof performance. [Solution] The light curtain 1 comprises a housing 110 having a metal case 111 extending in the longitudinal direction x and an end member 113 fixed to one end of the metal case 111, in which one of a pair of light-emitting and light-receiving elements that form a plurality of optical axes Oax along the longitudinal direction x is disposed inside, a cover 130 that transmits light from the light-emitting element 160 and is attached to the housing 110 so as to intersect with the plurality of optical axes Oax, a substrate 190 disposed in a sealed space formed by the housing 110 and the cover 130 and on which one of the optical elements is mounted, a conductive fixing member 340 that fixes the end member 113 to the metal case 111 and is electrically connected to the metal case 111, and an AC discharge unit 350 that performs capacitor coupling between the metal case 111 and the grounding wiring of the substrate 190 via the fixing member 340.

Description

Technical Field

[0001] The present invention relates to a light curtain.

Background Art

[0002] A light curtain is a form of a multi-axis photoelectric sensor. The light curtain detects a person or an object according to whether the optical axes formed between a projector and a light receiver are blocked.

[0003] For example, the light curtain is used as a means for detecting an intruder into a dangerous area and outputting a stop signal to a machine. Therefore, the light curtain is often used in an environment where dust is flying or water is splashing, such as in a factory where a large number of machines are installed. The light curtain used in such an environment is required to have a dust and waterproof performance of a certain grade or higher.

[0004] In addition, as a standard representing the dust and waterproof performance, the IP [Ingress Protection] grade is widely known. In a conventional light curtain, for example, a case extruded into a U-shaped cross section is adopted, and a front cover constituting a light projecting and receiving window is joined to the case in a liquid-tight manner, thereby ensuring an IP grade of a certain grade or higher. In addition, a metal case may be adopted to enhance the robustness of the light curtain. This makes it easier to further ensure the IP grade.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, in light curtains, as one of the EMC (electromagnetic compatibility) countermeasures, capacitor coupling is used to discharge AC signals such as noise from the grounding wiring of the control board to the metal case. However, the surface of the metal case is often covered with an insulating layer by surface treatment such as painting or anodizing. Therefore, in conventional light curtains, electrical conductivity is generally achieved by pressing the terminals against the cut end face of the metal case that is not covered with an insulating layer. However, in the conventional configuration described above, it is necessary to provide a separate board from the control board or add custom parts in order to extend the terminals to the cut end face of the metal case. Therefore, this can significantly affect the size and cost of the light curtain.

[0007] For example, if a separate circuit board with coupling capacitors is required in addition to the main control board, both circuit boards must be housed inside the metal case. This tends to increase the size of the metal case. On the other hand, if coupling is performed using capacitors mounted on the control board, the harness needs to be routed to the cut edge of the metal case. This, too, can hinder the miniaturization of the metal case. Furthermore, the cut edge of the metal case has a very small surface area. Therefore, ensuring stable conductivity between the cut edge of the metal case and the terminals is inherently difficult.

[0008] In view of the above problems, the present invention aims to miniaturize the light curtain while maintaining dustproof and waterproof performance. [Means for solving the problem]

[0009] The light curtain according to the present invention comprises, for example, a housing having a metal case extending in the longitudinal direction and an end member fixed to one end of the metal case, in which one of a pair of light-emitting and light-receiving elements that form a plurality of optical axes along the longitudinal direction is disposed inside, a cover that transmits light from the light-emitting element and is attached to the housing so as to intersect the plurality of optical axes, a substrate disposed in a sealed space formed by the housing and the cover and on which the one optical element is mounted, a conductive fixing member that fixes the end member to the metal case and is electrically conductive with the metal case, and an AC discharge unit that performs capacitor coupling between the metal case and the grounding wiring of the substrate via the fixing member.

[0010] Further details regarding other features, elements, steps, advantages, and characteristics will become clearer from the embodiments for carrying out the invention and the accompanying drawings. [Effects of the Invention]

[0011] According to the present invention, by performing capacitor coupling between the metal case and the grounding wiring via a conductive fixing member that fixes the metal case and the end member of the housing, it is possible to miniaturize the light curtain while maintaining dustproof and waterproof performance. [Brief explanation of the drawing]

[0012] [Figure 1] This diagram shows the schematic configuration of a light curtain. [Figure 2] This is a perspective view showing the overall configuration of the floodlight. [Figure 3] This is a front view showing the overall configuration of the floodlight. [Figure 4] This is a perspective view showing one end of a floodlight. [Figure 5] This is a functional block diagram of the light curtain. [Figure 6] This is a diagram showing a first embodiment of a floodlight. [Figure 7] This figure shows an example of the arrangement of light sources for indicator lights in the first embodiment. [Figure 8] It is a new-old comparison diagram showing the relationship between the presence or absence of function expansion and the fixture. [Figure 9] It is a diagram showing the relationship between the presence or absence of function expansion and the size in the thickness direction. [Figure 10] It is a diagram showing the mounting mechanism of the end cap. [Figure 11] It is a new-old comparison diagram of the cable connection structure. [Figure 12] It is a cross-sectional view showing an example of a directly drawn-out type cable connection. [Figure 13] It is a cross-sectional view showing an example of the fixing structure between the metal case and the end cap. [Figure 14] It is a diagram showing the bottom surface, α-α cross-section, and β-β cross-section of the housing. [Figure 15] It is a diagram showing a configuration example of the AC discharge part. [Figure 16] It is a diagram showing a configuration example of the conduction member. [Figure 17] It is a cross-sectional view showing the outer shape of the housing.

Embodiments for Carrying Out the Invention

[0013] <Light curtain> FIG. 1 is a diagram showing a schematic configuration of a light curtain. The light curtain 1 in this configuration example is an aspect of a multi-optical axis photoelectric sensor and generally includes a pair of light emitters 100 and light receivers 200.

[0014] The light curtain 1 detects a person or an object according to whether at least one of a plurality of optical axes (six optical axes Oax1 to Oax6 in this figure) formed at intervals between the light emitters 100 and the light receivers 200 arranged in parallel is blocked. For example, the light curtain 1 can be provided at the entrance of a danger area where a danger source such as a press device is placed and used as a safety device for detecting the intrusion or presence of an operator.

[0015] The light emitter 100 and the light receiver 200 each comprise a long (maximum of 2m or more) housing 110 and 210, and cables 120 and 220 connected thereto.

[0016] The housing 110 has a hollow metal case 111 extending in the 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 housing 210 has a hollow metal case 211 extending in the longitudinal direction, and hollow end caps 212 and 213 (corresponding to end members) connected to both ends of the metal case 211, respectively. In this embodiment, the longitudinal direction is a direction substantially parallel to the direction in which the multiple optical axes formed between the light emitter 100 and the light receiver 200 are spaced apart from each other.

[0017] Thus, by using high-rigidity metal cases 111 and 211 as the cases for housings 110 and 210, the long housings 110 and 210 become less prone to deformation. Consequently, adjusting the placement of the light emitter 100 and light receiver 200 (for example, adjusting the angle to position them parallel) becomes relatively easy. Alternatively, inexpensive and lightweight extruded aluminum products may be used as the metal cases 111 and 211. In that case, the cross-section of the metal cases 111 and 211 will be the same shape regardless of where they are cut in the extrusion direction (=longitudinal direction).

[0018] The end caps 112, 113, 212, and 213 may each be formed by injection molding using a resin material, or by die casting using a metal material such as zinc. The lower end caps 113 and 213 in this figure may be fitted with interfaces for cables 120 and 220. Therefore, the end caps 113 and 213 may be larger than the upper end caps 112 and 212 in this figure.

[0019] <Floodlight> Figures 2 and 3 are perspective and front views, respectively, showing the overall configuration of the floodlight 100. Figure 4 is a perspective view showing one end of the floodlight 100.

[0020] As mentioned earlier, the floodlight 100 comprises a housing 110 and a cable 120. The housing 110 also includes a metal case 111 and end caps 112 and 113. Furthermore, the floodlight 100 includes a front cover 130, an indicator light 140, and a bumper section 150.

[0021] The front cover 130 is a long, translucent plate attached to cover the front opening (=detection window) of the housing 110. In the front opening of the housing 110, light-emitting elements 161 to 166, each for forming multiple optical axes Oax1 to Oax6, are arranged at equal intervals along the longitudinal direction. In other words, the front cover 130 is attached to the housing 110 so as to intersect with the multiple optical axes Oax1 to Oax6. The front cover 130 may be an extruded translucent resin plate (such as an acrylic plate) or a glass plate. In this embodiment, the translucency of the material used as the front cover 130 refers to a translucency such that the light from the light-emitting elements 161 to 166 forming the multiple optical axes Oax1 to Oax6 is not excessively diffused outside the optical axis, and is received by the light-receiving elements 261 to 266 (described later) with a certain amount of light or more. Since the front cover 130 is made of a light-transmitting material, the worker can see the light-emitting elements 161-166 through the front cover 130.

[0022] Furthermore, it is preferable that the end cap 113 has a light-emitting element (light-emitting element 166 in Figure 3) corresponding to at least one of the multiple optical axes Oax1 to Oax6. That is, it is preferable that the light-emitting elements 161 to 166 be arranged at equal intervals in the longitudinal direction over the entire length of the floodlight 100 from one end to the other. Also, it is preferable that the cable 120 extends from the back (or side) of the end cap 113 rather than from the bottom surface of the end cap 113. With this configuration, the floodlight 100 can be installed very close to the installation surface (floor, etc.). Therefore, dead space can be eliminated.

[0023] The indicator light 140 is controlled to flash on and off with a light color corresponding to, for example, the operating status of the light curtain 1 (such as the optical axis detection status and self-diagnosis results) or work instructions regarding the loading and unloading of objects. In other words, the indicator light 140 functions as an operation indicator light or a work instruction light. Therefore, by looking at the indicator light 140 of the light curtain 1, the worker can visually recognize the operating status of the light curtain 1 or work instructions.

[0024] In particular, the indicator light 140 is positioned longitudinally outward from at least one of the outer surfaces of the front cover 130 and the housing 110, or is formed in series with the front cover 130 (details of the structure will be described later). Referring to this figure, the indicator light 140 is provided on both sides of the front cover 130. With the indicator light 140 positioned or formed in this manner, a highly visible display can be provided without impairing the rigidity of the housing 110. More specifically, the indicator light 140 is a long extruded product, and is positioned so that the longitudinal direction of the indicator light 140 is aligned with the longitudinal direction of the housing 110. Note that the indicator light 140 only needs to be positioned along the longitudinal direction of the housing 110, and its manufacturing method is not limited to extrusion molding, and the shape of the indicator light 140 does not have to be long. For example, a configuration in which multiple members that function as indicator lights 140 are positioned along the longitudinal direction of the housing 110 is also possible.

[0025] Furthermore, the indicator light 140 is a light-diffusing member that diffuses light incident from an indicator light source 170 (not shown) housed inside the housing 110 in various directions. More specifically, the indicator light 140 contains a light diffuser that diffuses light in various directions. In a configuration where the light-diffusing member of the indicator light 140 contains a light diffuser, the indicator light 140 can be illuminated relatively uniformly even if the indicator light source 170 is small relative to the surface size of the indicator light 140, thus enabling a highly visible display. In this embodiment, the indicator light 140 is made of a transparent resin to which fine particles have been added, and is therefore milky white. If the base resin is not transparent but a specific color, the color will be a mixture of that specific color and milky white. In addition to the configuration containing a light diffuser, the indicator light 140 can also be made of a milky white resin (such as silicone) to achieve relatively uniform illumination. The light-diffusing member for the indicator light 140 can be any member that diffuses the light from the indicator light source 170 so that it can be seen from more directions, or any member that diffuses the light from the indicator light source 170 to such an extent that the outline of the indicator light source 170 is difficult to see from outside the indicator light 140. For example, a light-diffusing member whose surface is processed to diffuse the light from the indicator light source 170 may be arranged as the indicator light 140. As a surface processing that diffuses light, for example, texturing is known. With a configuration in which a light-diffusing member with a processed surface is arranged as the indicator light 140, it becomes easier to manufacture a member that has a region that diffuses light relatively easily and a region that does not diffuse light relatively easily.

[0026] The bumper section 150 protrudes outward from the region of the front cover 130's outer surface that intersects with multiple optical axes Oax1 to Oax6, and is positioned along the longitudinal direction of the housing 110 (details of the structure will be described later).

[0027] As shown in the figure, the bumper sections 150 are formed in pairs, protruding from both sides of the front cover 130. In other words, the front cover 130 is positioned in a narrow valley between the pair of bumper sections 150 (the twin bumpers proposed by the applicant) located on both sides and rising forward. Therefore, even if an object collides with the front of the floodlight 100, the impact is absorbed by the bumper sections 150. Consequently, the front cover 130 is less likely to be damaged. The bumper sections 150 may be made of a hard material such as metal.

[0028] Furthermore, the configuration of the light receiver 200 is basically the same as that of the light emitter 100. Therefore, in the explanatory text for Figures 2 to 4, the configuration of the light receiver 200 can be understood by appropriately substituting light emitter 100 and light-emitting elements 161 to 166 with light receiver 200 and light-receiving elements 261 to 266, respectively, and appropriately substituting other 100-series codes with 200-series codes. The same applies to the explanations that follow.

[0029] <Function Block> Figure 5 is a functional block diagram of the light curtain 1. In the light curtain 1 of this configuration example, the floodlight 100 includes an indicator light 140, light-emitting elements 161 to 166, a light source 170 for the indicator light, a control circuit 181, and a communication circuit 182.

[0030] The light-emitting elements 161 to 166 are arranged at equal intervals along the longitudinal direction of the light emitter 100 at a predetermined pitch. Based on the light emission control signal input from the control circuit 181, the light-emitting elements 161 to 166 sequentially emit multiple light beams toward the light receiver 200 (particularly the light-receiving elements 261 to 266) in a time-division manner to form multiple optical axes Oax1 to Oax6, respectively. Note that the light-emitting elements 161 to 166 may be, for example, light-emitting diodes that emit infrared light.

[0031] The indicator light source 170 supplies light to the indicator light 140 for display purposes based on the display control signal input from the control circuit 181. The indicator light source 170 may be capable of switching between multiple light emission colors (e.g., red, green, and orange) depending on the operating state of the light curtain 1 or work instructions.

[0032] Furthermore, the indicator light source 170 is preferably pulsed on at a timing that is temporally offset from the light emission / reception timing of each of the multiple optical axes Oax1 to Oax6. With this type of on / off control, interference with optical axis detection by the indicator light source 170 can be suppressed.

[0033] The indicator light 140 diffuses the light incident from the indicator light source 170 in various directions. By looking at the indicator light 140, the worker can visually recognize the operating status of the light curtain 1 or work instructions.

[0034] The control circuit 181 receives instructions from the light receiver 200 and generates a light emission control signal to sequentially drive the light-emitting elements 161 to 166 in a time-division manner. The control circuit 181 also generates a display control signal to turn the indicator light source 170 on and off with an arbitrary emission color. Furthermore, the control circuit 181 exchanges various information with the communication circuit 182.

[0035] The communication circuit 182 communicates with the light receiver 200 (particularly the communication circuit 282) via wired or wireless means. For example, the communication circuit 182 receives input from the light receiver 200 regarding the operating status of the light curtain 1 (such as the optical axis detection status and self-diagnosis results) and transmits it to the control circuit 181.

[0036] On the other hand, the light receiver 200 includes an indicator light 240, light receiving elements 261 to 266, a light source 270 for the indicator light, 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, with the same pitch as the light-emitting elements 161 to 166. Based on the light-receiving control signal input from the control circuit 281, the light-receiving elements 261 to 266 sequentially receive multiple light beams in a time-division manner to form multiple optical axes Oax1 to Oax6. The light-receiving elements 261 to 266 may also be, for example, photodiodes or phototransistors that output an electrical signal corresponding to the amount of infrared light received.

[0038] The indicator light source 270 supplies light to the indicator light 240 for display based on the display control signal input from the control circuit 281. Like the indicator light source 170, the indicator light source 270 may be able to switch between multiple light emission colors (e.g., red, green, and orange) depending on the operating status of the light curtain 1 or work instructions.

[0039] Furthermore, the indicator light source 270 is preferably pulsed on at a timing that is temporally offset from the light emission / reception timing of each of the multiple optical axes Oax1 to Oax6. With this type of on / off control, interference with optical axis detection by the indicator light source 270 can be suppressed.

[0040] Furthermore, consider the case where the indicator light source 270 is continuously lit. In this case, even if the DC light from the indicator light source 270 is received by the light receiving elements 261 to 266, it is desirable to provide a saturation prevention circuit (= DC component subtraction circuit) so that the electrical signals output from the light receiving elements 261 to 266 do not become saturated.

[0041] The indicator light 240 diffuses the light incident from the indicator light source 270 in various directions. By looking at the indicator light 240, the worker can visually recognize the operating status of the light curtain 1 or work instructions.

[0042] Furthermore, since indicator lights 140 and 240 are provided on both the light emitter 100 and the light receiver 200, a highly visible display can be achieved.

[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, synchronized with the drive timing of each of the light-emitting elements 161 to 166. The control circuit 281 also generates a display control signal to turn the indicator light source 270 on and off with an arbitrary emission color. Furthermore, 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-ingress / light-blocking state of each of the multiple optical axes Oax1 to Oax6. For example, the control circuit 281 may output an operation permission signal (ON signal) when all of the multiple optical axes Oax1 to Oax6 are in the light-ingress state. On the other hand, the control circuit 281 may output an operation disallowance signal (OFF signal) when at least one of the multiple optical axes Oax1 to Oax6 is in the light-blocking state.

[0045] Furthermore, the control circuit 281 may be equipped with a self-diagnosis function to determine whether it is in a state where it can correctly monitor the light-ingress / light-blocking state of each of the multiple optical axes Oax1 to Oax6. As a self-diagnosis method, for example, the control circuit 281 and the output circuit 283 (e.g., OSSD [Output Signal Switching Device] output) may be multiplexed, and the match / mismatch of the multiplexed signals may be determined.

[0046] For example, if the multiplexed signals match, an OK diagnosis (a diagnosis result indicating that the system is in a state where it can be properly monitored) is issued. On the other hand, if the multiplexed signals do not match, an NG diagnosis (a diagnosis result indicating that the system is not in a state where it can be properly monitored) is issued. In the event of an NG diagnosis, an operation prohibition signal (OFF signal) may be output regardless of the light input status of each of the multiple optical axes Oax1 to Oax6.

[0047] Information that can be used for safety control is designated as safety information, while general information that cannot be used for safety control is designated as non-safety information. For example, the OSSD output is a type of safety information. The signals used to control the on / off state of the indicator light sources 170 and 270 may be signals indicating safety information or signals indicating non-safety information.

[0048] The communication circuit 282 communicates with the floodlight 100 (particularly the communication circuit 182) by wire or wireless means. The communication circuit 282 receives information from the control circuit 281 regarding the operating status of the light curtain 1 (such as the optical axis detection status and self-diagnosis results) and transmits it to the floodlight 100.

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

[0050] The input circuit 284 communicates with external devices (e.g., safety controllers) via wired or wireless means. For example, the input circuit 284 receives input from external devices regarding work instructions for loading and unloading objects and transmits them to the control circuit 281.

[0051] <First Embodiment> Figure 6 is a diagram showing a first embodiment of the floodlight 100 (a schematic cross-sectional view when the metal case 111 of the floodlight 100 is cut at an arbitrary position in the longitudinal direction). The floodlight 100 of this embodiment comprises a housing 110 (only the metal case 111 is depicted in this figure), a front cover 130, an indicator light 140, a bumper portion 150, a light source for the indicator light 170, a circuit board 190, and a light shielding plate 191.

[0052] The metal case 111 is an extruded product that extends in the longitudinal direction of the floodlight 100. As shown in the figure, the metal case 111 consists of a main body 111a, a pair of first protrusions 111b, and a pair of second protrusions 111c.

[0053] The main body 111a is a hollow member with a U-shaped cross-section and an opening on the upper side of the paper (= the front side of the floodlight 100). The internal space of the main body 111a houses the indicator light source 170, the substrate 190, and the light shielding plate 191.

[0054] A pair of first protruding strips 111b project inward from the inner surfaces of the left and right walls of the main body 111a toward the inside of the opening. That is, the pair of first protruding strips 111b are arranged facing each other at a predetermined distance, straddling the optical axis intersection region X (= the region where multiple optical axes Oax1 to Oax6 intersect). The pair of first protruding strips 111b also function as cover mounting parts for supporting the front cover 130. As described above, a translucent material is used for the front cover 130, but it is sufficient that at least the optical axis intersection region X is translucent and the optical axes Oax1 to Oax6 are not obstructed. For example, in this embodiment, the portion that contacts the pair of first protruding strips 111b does not necessarily have to be translucent.

[0055] A pair of second protrusions 111c extend further upward from the upper ends of the left and right walls of the main body 111a. Furthermore, the tips of each of the second protrusions 111c are bent inward towards the opening. The pair of second protrusions 111c function as a bumper portion 150 to protect the front cover 130. In this embodiment, the aforementioned bumper portion 150 is formed from the metal case 111. Therefore, the robustness of the floodlight 100 can be increased.

[0056] The front cover 130 is supported (suspended) at both ends, straddling a pair of first protruding strips 111b. The front cover 130 allows light to pass through that forms multiple optical axes Oax1 to Oax6 in the optical axis intersection region X. The area between the front cover 130 and the pair of first protruding strips 111b (see thick line α) is treated to improve liquid resistance. For example, a packing is placed, or it is bonded with a liquid-resistant adhesive. As will be described later, the indicator light 140 increases the adhesion between the front cover 130 and the first protruding strips 111b, further improving liquid resistance.

[0057] The indicator lights 140 are positioned on both sides of the front cover 130, adjacent to the bumper section 150. Referring to this figure, the indicator lights 140 are positioned along the longitudinal direction of the floodlight 100 in the area sandwiched between the tip (bent portion) of the first protruding strip 111b and the second protruding strip 111c, that is, in the area sandwiched between the bumper section 150 and the front cover 130.

[0058] The indicator light 140 diffuses the light incident from the indicator light source 170 through the front cover 130 in various directions. For example, the indicator light 140 may be provided with a taper to refract and diffuse the light incident from the indicator light source 170 toward the inside of the opening.

[0059] With the indicator lights 140 arranged in this manner, they are easily visible even from the side of the floodlight 100. Therefore, in a small (slim-diameter) light curtain 1 using a metal case 111, highly visible displays can be provided without compromising the rigidity of the housing 110. In particular, when a pair of bumper sections 150 are provided protruding from both sides of the front cover 130, the improvement in visibility due to the above arrangement can become even more pronounced.

[0060] Furthermore, in the floodlight 100 of this embodiment, the indicator light 140 also functions as a pressing member for pressing and fixing the front cover 130 downward (towards the first protruding strip 111b). Therefore, the airtightness between the front cover 130 and the first protruding strip 111b is increased, which prevents liquid from entering the inside of the metal case 111 and improves liquid resistance. In order for the indicator light 140 to function as a pressing member, it is desirable that the indicator light 140 has appropriate elasticity.

[0061] The indicator light source 170 is mounted on the main surface of the substrate 190 (= the surface facing the front cover 130). The indicator light source 170 supplies light for display to the indicator light 140 via the front cover 130. As shown in this figure, the light emitted from the indicator light source 170 passes between the pair of first protruding strips 111b without being obstructed by the pair of first protruding strips 111b and is supplied to the indicator light 140 via the front cover 130.

[0062] The number of indicator light sources 170 is not limited. For example, the indicator light sources 170 may be arranged intermittently in multiple locations along the longitudinal direction of the floodlight 100, or they may be formed in a continuous series.

[0063] Furthermore, the indicator light source 170 may be equipped with a lens for controlling the direction of the emitted light. For example, a lens may be provided that is optically designed to reduce the angle of light spread in the left-right direction of the figure and increase the angle of light spread in the depth direction of the figure. Such a lens makes it possible to reduce the number of indicator light sources 170 while suppressing interference with multiple optical axes Oax1 to Oax6.

[0064] The type of lens may be a point-symmetric lens (single arrangement) or a cylindrical lens (series arrangement of extruded products).

[0065] The light-shielding plate 191 is provided 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 the multiple optical axes Oax1 to Oax6.

[0066] Furthermore, consider the case where the optical axis Oax1 to Oax6 is formed by infrared light, and visible light (red light, green light, or orange light, etc.) is emitted from the indicator light source 170. In this case, a filter that transmits infrared light and blocks visible light may be provided in the light receiver 200. In particular, when an indicator light 240 is provided in the light receiver 200, it is sufficient to have a configuration in which a filter that transmits infrared light and blocks visible light is arranged so as not to obstruct the display of the indicator light 240. The filter may be provided in the light receiving elements 261 to 266, or it may be provided in the lens that guides light to the light receiving elements 261 to 266.

[0067] Figure 7 shows an example of the arrangement of the indicator light source 170 in the first embodiment. As shown in this figure, the light-emitting elements 161 to 166 may be arranged at equal intervals along the longitudinal direction of the substrate 190 in the central region 190a of the substrate 190. On the other hand, the indicator light source 170 may be arranged at equal intervals along the longitudinal 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 may be arranged so that their positions in the longitudinal direction of the substrate 190 are offset from each other (staggered). With such an arrangement, mutual interference between the light-emitting elements 161-166 and the indicator light source 170 is suppressed.

[0069] The number and arrangement of the indicator light sources 170 are not limited to the arrangement example shown in this figure. For example, the number of indicator light sources 170 may be reduced so that there is some unevenness in the light supplied to the indicator lights 140.

[0070] <Feature Enhancement> Figure 8 is a comparison diagram showing the relationship between the functional enhancements to the light curtain 1 and the mounting hardware. The upper part of the figure depicts the old configuration of the light curtain 1. On the other hand, the lower part of the figure depicts the new configuration of the light curtain 1. In this figure, the long side of the light curtain 1 is the x-axis, the short side is the y-axis, and the thickness direction (depth direction) is the z-axis.

[0071] The light curtain 1 in this figure can be understood as the previously mentioned light source 100. However, in the following explanation, if the 100-series symbols are read as 200-series symbols, the light curtain 1 in this figure can also be understood as the light receiver 200.

[0072] In this diagram, in both the upper and lower sections, the left column shows the case without functional extensions, the center column shows the case with the series connection cable 4 connected, and the right column shows the case with the operation indicator light 5 connected. The series connection cable 4 and the operation indicator light 5 are attached to the end cap 112 of the light curtain 1 and can be understood as functional extension parts 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 indicate the operating status of the light curtain 1. In this way, a multi-optical axis photoelectric sensor with expandable functionality is constructed using the light curtain 1 and various functional extension parts that can be attached to and detached from it.

[0073] Mounting fixtures 2 and 2a-2e each correspond to jigs for attaching the light curtain 1 to the base 3. In other words, a multi-axis photoelectric sensor comprising mounting fixtures 2 and 2a-2e and the light curtain 1 attached to mounting fixtures 2 and 2a-2e can be installed on the base 3.

[0074] Incidentally, as shown in the upper part of this figure, the old configuration of the light curtain 1 is attached to the base 3 with a common mounting bracket 2, regardless of whether the series connection cable 4 and the operation indicator light 5 are connected or not. The mounting bracket 2 is designed to minimize the gap between the light curtain 1 and the base 3. Therefore, the old configuration of the light curtain 1 is designed so that the series connection cable 4 and the operation indicator light 5 do not protrude from the outer surface facing the base 3, for example, the rear surface. Referring to this figure, an excess space equal to the thickness of the series connection cable 4 or the operation indicator light 5 is secured on the rear surface of the end cap 112. Consequently, there is a limit to how small the housing 110 can be made in the old configuration of the light curtain 1.

[0075] On the other hand, as shown in the lower part of this figure, the new configuration of the light curtain 1 is designed to minimize the size of the housing 110, assuming the light curtain 1 is used alone, disregarding the thickness of the series connection cable 4 and operation indicator light 5 that may be connected when the function is expanded. Conversely, the new configuration of the light curtain 1 is designed to allow the series connection cable 4 and operation indicator light 5 to protrude from the rear 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 longitudinal direction of the light curtain 1 and are attached to the end cap 112 of the light curtain 1 so as to protrude from the rear surface of the light curtain toward the base 3.

[0077] As a result, in the new configuration of the light curtain 1, the size of the gap between the light curtain 1 and the base 3 changes depending on whether or not the functionality has been enhanced. Therefore, it is desirable to provide multiple types of mounting fixtures 2a to 2e for attaching the new configuration of the light curtain 1 to the base 3, depending on whether or not the functionality has been enhanced.

[0078] The mounting bracket 2a has a base portion a1. The base portion a1, for example, has its rear surface attached to the base 3 and receives the housing 110 of the light curtain 1 from the front. The mounting bracket 2a is used when the light curtain 1 is used alone. Therefore, like the mounting bracket 2 described above, the mounting bracket 2a can be configured so that there is as little gap as possible between the light curtain 1 and the base 3. Specifically, the thickness of the base portion a1 interposed between the light curtain 1 and the base 3 may be designed to be the minimum necessary.

[0079] The mounting bracket 2b is an L-shaped angle having main surfaces b1 and b2. Main surface b1 may be the xy surface to which it is attached to the base 3. Main surface b2 may be the yz surface to which it is attached to the end face of the end cap 112 in the longitudinal direction of the light curtain 1. Mounting bracket 2a is used when the light curtain 1 is used alone. Therefore, like the mounting bracket 2 described above, mounting bracket 2a may be configured so that there is as little gap as possible between the light curtain 1 and the base 3. Specifically, the length of the main surface b2 in the z-axis direction may be designed according to the thickness of the light curtain 1 in the z-axis direction.

[0080] Thus, when using the light curtain 1 alone, mounting brackets 2a and 2b, which are smaller in the thickness direction than the mounting brackets 2c to 2e described later, can be used. Therefore, by miniaturizing both the light curtain 1 and the mounting brackets 2a and 2b, the entire multi-axis photoelectric sensor can be installed in a space-saving manner.

[0081] The mounting fixture 2c has a base portion c1. The base portion c1, for example, has its rear surface attached to a base 3 and receives the housing 110 of the light curtain 1 from the front. The mounting fixture 2c is used when connecting the series connection cable 4. Therefore, the mounting fixture 2c may be configured to form a space for accommodating the protrusion 4a between the rear surface of the light curtain 1 and the base 3. Specifically, the thickness of the base portion c1 may be designed such that the distance from the rear surface of the light curtain 1 to the rear surface of the base portion c1 is greater than the thickness of the protrusion 4a.

[0082] The mounting bracket 2d is an L-shaped angle having main surfaces d1 and d2. Main surface d1 may be the xy surface to which it is attached to the base 3. Main surface d2 may be the yz surface to which it is attached to the end face of the end cap 112 in the longitudinal direction of the light curtain 1. The mounting bracket 2d is used when connecting the series connection cable 4. Therefore, the mounting bracket 2d may be configured to form a space for accommodating the protrusion 4a between the rear surface of the light curtain 1 and the base 3. Specifically, the length of the main surface b2 in the z-axis direction may be designed such that the distance from the rear surface of the light curtain 1 to the main surface d1 is greater than the thickness of the protrusion 4a.

[0083] The mounting fixture 2e has a base portion e1. The base portion e1, for example, has its rear surface attached to a base 3 and receives the housing 110 of the light curtain 1 from the front. The mounting fixture 2e is used when connecting the operation indicator light 5. Therefore, the mounting fixture 2e may be configured to form a space for accommodating the protrusion 5a between the rear surface of the light curtain 1 and the base 3. Specifically, the thickness of the base portion e1 may be designed such that the distance from the rear surface of the light curtain 1 to the rear surface of the base portion e1 is greater than the thickness of the protrusion 5a.

[0084] Thus, when expanding the functionality of the light curtain 1, mounting fixtures 2c to 2e can be used that can absorb the thickness of the protrusions 4a and 5a, respectively. Therefore, even if the protrusions 4a and 5a protrude from the rear surface of the light curtain 1 toward the base 3, it will be less likely to interfere with the installation of the light curtain 1.

[0085] Please note that this diagram is for illustrative purposes only. Following this diagram, by developing a product line that includes a light curtain, various detachable functional extensions, and multiple types of mounting hardware, it will be possible to flexibly respond to a wide variety of user needs.

[0086] Figure 9 shows the relationship between the presence or absence of functional enhancements in the light curtain 1 and its size in the thickness direction (depth direction). The upper part of this figure depicts the side view of the light curtain 1. On the other hand, the lower part of this figure depicts the cross-section, i.e., the zx cross-section, when the light curtain 1 is cut perpendicular to the y-axis.

[0087] The light curtain 1 comprises a metal case 111, an end cap 112, and a substrate 190. The metal case 111 can be understood as the main body of the light curtain 1, which forms multiple optical axes along its longitudinal direction. The end cap 112 can be understood as an end member fixed to one end of the metal case 111. The substrate 190 extends from the metal case 111 to the end cap 112. Optical elements and their control circuits that form multiple optical axes are mounted on the substrate 190. Multiple optical elements are arranged on the substrate 190 at predetermined intervals along its longitudinal direction. Multiple optical axes are formed not only on the metal case 111 but also on the end cap 112. The substrate 190 may be divided into multiple sections along its longitudinal direction.

[0088] As shown in the center and right columns of this figure, the series connection cable 4 and the operation indicator light 5 are mounted on the rear surface of the end cap 112 in a direction perpendicular to the longitudinal direction of the light curtain 1, i.e., from the z-axis direction. At this time, protrusions 4a and 5a protrude from the rear surface of the light curtain 1, respectively. Electrical components, electrical wiring, and circuit boards can be housed in the protrusions 4a and 5a.

[0089] The operation indicator light 5 includes, for example, a light-emitting part 5x, a base 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 may be dome-shaped. The base 5y abuts against the end face of the end cap 112 in the longitudinal direction of the light curtain 1 and supports the light-emitting part 5x. The base 5y may be fastened to the end cap 112 with screws or the like. This enhances the dustproof and waterproof performance of the light curtain 1. The connecting part 5z extends from the base 5y along the longitudinal direction of the light curtain 1 to the rear surface of the end cap 112.

[0090] On the other hand, as shown in the left column of this figure, when the series connection cable 4 and the functional extension parts such as the operation indicator light 5 are not attached, that is, when the light curtain 1 is used alone, the termination cover 112x is attached to the rear surface of the end cap 112. The termination cover 112x can be formed so as to be flush with the rear surface of the light curtain 1 without protruding.

[0091] The termination covers 112x, the series connection cables 4, and the operation indicator lights 5 are directly connected to the circuit board 190 via connectors 301 provided on the light curtain 1. With this configuration, the housing 110 can be made smaller compared to the conventional configuration which has a separate sub-board for function expansion.

[0092] Figure 10 shows the mounting mechanism for the end cap 112. The top row of this figure depicts the rear surface of the light curtain 1. The bottom three rows of this figure depict the mounting surfaces of the termination cover 112x, the series connection cable 4, and the operation indicator light 5, respectively, that is, the surfaces that face 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 that extends to an end cap 112. The connector 301 may be positioned on the opposite side of the substrate 190 from the light emission direction or light reception direction of the optical element, i.e., on the rear 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, various functional extensions can be detachably attached to the connector 301 from a direction perpendicular to the longitudinal direction of the light curtain 1, i.e., the z-axis direction. For example, one of the following can be selectively attached to the connector 301: a terminal cover 112x, a series connection cable 4, and an operation indicator light 5.

[0095] The termination cover 112x is attached to the connector 301 when neither the series connection cable 4 nor the operation indicator light 5 is installed. The termination cover 112x can be understood as a cover member for covering the opening 112y of the end cap 112 when the light curtain 1 is used alone. However, the termination cover 112x is not merely a cover member, but also has the function of making the light curtain 1 recognize that it is the end of the line.

[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 attached to and detached from connector 301, respectively. When the terminal cover 112x is attached to the end cap 112, connectors 301 and 311 are connected. When the series connection cable 4 is attached to the end cap 112, connectors 301 and 321 are connected. When the operation indicator light 5 is attached to the end cap 112, connectors 301 and 331 are connected.

[0097] Furthermore, the light curtain 1 has a guide portion 302. The guide portion 302 guides the connectors 311, 321, and 331 to their respective connection positions with the connector 301. The guide portion 302 may be a rectangular frame-shaped member surrounding the connector 301. The guide portion 302 may be designed so that its height in the z-axis direction is slightly greater than that of the connector 301.

[0098] For example, when the terminal cover 112x is attached to the end cap 112, the terminal cover 112x is first positioned relative to the end cap 112 by the guidance of the guide portion 302, and then the connector 301 and connector 311 are connected.

[0099] The same applies when the series connection cable 4 or the operation indicator light 5 is attached to the end cap 112. That is, after the series connection cable 4 or the operation indicator light 5 is positioned relative to the end cap 112, the connector 301 and the connector 321 or 331 are connected.

[0100] With this configuration, it becomes less likely for the connectors to come into contact with each other when their relative positions are misaligned. Therefore, damage to connector 301 and connectors 311, 321, and 331 can be prevented.

[0101] The terminal covers 112x, the series connection cables 4, and the operation indicator lights 5 may each be fastened to the end caps 112 with screws or the like. This configuration enhances 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. With this configuration, the load on the substrate 190 is reduced when connector 301 is connected to connectors 311, 321, or 331. Therefore, the substrate 190 is less likely to deform, and the impact on the optical axis is reduced.

[0103] The terminal cover 112x may include a guide portion 312 that guides connector 311 to the connection position with connector 301. The series connection cable 4 may include a guide portion 322 that guides connector 321 to the connection position with connector 301. The operation indicator light 5 may include a guide portion 332 that guides connector 331 to the connection position with connector 301. With this configuration, damage due to accidental contact between connectors can be prevented. However, if guide portion 302 is provided on the light curtain 1, guide portions 312, 322 and 332 are not essential.

[0104] The terminal cover 112x, the series connection cable 4, and the operation indicator light 5 each have packings 313, 323, and 333, respectively. When the terminal cover 112x is attached to the end cap 112, the packing 313 seals the area around the opening 112y. When the series connection cable 4 is attached to the end cap 112, the packing 323 seals the area around the opening 112y. When the operation indicator light 5 is attached to the end cap 112, the packing 333 seals the area around the opening 112y.

[0105] The termination cover 112x and the operation indicator light 5 each have DIP switches 314 and 334, respectively. DIP switches 314 and 334 may also be used as interference prevention setting switches. For example, by using 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 performing such interference prevention settings, for example, missynchronization or malfunction between adjacent light curtains can be prevented.

[0106] <Cable connection> Figure 11 is a comparison diagram of the old and new cable connection structures in the light curtain 1. The left column of this figure depicts the old structure (connector type). The right column of this figure depicts the new structure (direct lead type). As shown in this figure, the cable 120 is connected to the end cap 113 of the light curtain 1. The end cap 113 is provided at the end of the light curtain 1 opposite to the end cap 112 from which the series connection cable 4 or the operation indicator light 5 can be attached and detached.

[0107] In the old structure, the cable 120 can be attached to and detached from the end cap 113 via the connector 121. Therefore, the number of pins on the cable 120 can be arbitrarily changed according to user needs. However, in the old structure, the connector 121 protrudes from the rear surface of the light curtain 1. Therefore, it may be difficult to install in a space-saving manner. For example, referring to Figure 8 mentioned earlier, when the light curtain 1 is used alone, it may be difficult to attach it to the base 3 using the mounting fixtures 2a and 2b.

[0108] In light of the above considerations, in the new structure, the cable 120 does not protrude from the outer surface of the light curtain 1, but is instead drawn directly from the end cap 113 along the longitudinal direction of the light curtain 1. Therefore, installation in a space-saving manner is made easier.

[0109] The cable 120 may also be a so-called pigtail cable. That is, the cable 120 may have a connector 122 at its end. The connector 122 may be a highly versatile M12 connector. With this configuration, the number of pins of the cable (not shown) attached to and detached from the connector 122 can be arbitrarily changed according to user needs. In addition, for example, the function and operation of the light curtain 1, such as enabling or disabling the communication function, may be switched depending on the number of pins of the cable attached to and detached from the connector 122.

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

[0111] As shown in this figure, the cable 120 may be directly connected to the circuit board 190 by a crimp connector 123. Alternatively, the cable 120 and the circuit board 190 may be directly connected by soldering.

[0112] <End cap fixing> Next, a method for fixing the end cap 113 is proposed with reference to Figures 13 and 14. Figure 13 is a cross-sectional view showing an example of a fixing structure between the metal case 111 and the end cap 113. Figure 13 can be understood as the zx cross-section when the light curtain 1 is cut perpendicular to the y-axis, specifically the γ-γ cross-section in Figure 14. Figure 14 shows the bottom surface of the light curtain 1, the α-α cross-section and β-β cross-section in Figure 13.

[0113] The light curtain 1 comprises a housing 110, a front cover 130, a circuit board 190, screws 340, an AC discharge section 350, and packings 361 and 362. The housing 110 has a metal case 111 and an end cap 113.

[0114] The metal case 111 is a hollow member that extends along the longitudinal direction of the light curtain 1. The surface of the metal case 111 is treated with an insulating treatment such as painting and anodizing.

[0115] Inside the metal case 111, a light-emitting element 160 is arranged to form multiple optical axes Oax along the longitudinal direction of the light curtain 1. The light-emitting element 160 can be understood as an optical element corresponding to, for example, the aforementioned light-emitting elements 161 to 166.

[0116] A portion of the metal case 111 may function as a bumper portion 150. The bumper portion 150 may protrude beyond the outer surface of the front cover 130 along multiple optical axes Oax. This configuration enhances the robustness of the light curtain 1.

[0117] The metal case 111 has a screw hole 111d for receiving the tip of the screw 340. The screw hole 111d may be formed as a through hole extending from one end face to the other end face of the metal case 111 along the longitudinal direction of the light curtain 1. The screw hole 111d has a first region 111d1 and a second region 111d2. The screw holes 111d may be provided in pairs on either side of the optical axis Oax, as shown in the α-α and β-β cross sections of Figure 14.

[0118] The first region 111d1 can be understood as the region of the screw hole 111d that is close to the end face of the metal case 111, specifically, the region close to the surface facing the end cap 113. The first region 111d1 may have a screw groove that engages with the threads engraved on the tip of the screw 340. The first region 111d1 is not subjected to insulating treatment such as painting or anodizing. Therefore, the metal case 111 can establish electrical conductivity with the screw 340 in the first region 111d1 of the screw hole 111d.

[0119] The second region 111d2 can be understood as the region of the screw hole 111d excluding the first region 111d1. The second region 111d2 may open facing the substrate 190 and function as a locking groove supporting the locking projection 371 of the holder 370 that supports the substrate 190. That is, the metal case 111 may be provided with a pair of locking grooves on either side of the holder 370.

[0120] The holder 370 has a pair of locking projections 371. Each of the pair of locking projections 371 is fitted into and supported in a locking groove, i.e., a second region 111d2 of a screw hole 111d, provided in the metal case 111.

[0121] Each of the pair of locking projections 371 may have a position adjustment mechanism 372. Each of the pair of position adjustment mechanisms 372 may be an elastic member that presses against the inner wall of the locking groove provided in the metal case 111, that is, the inner wall of the second region 111d2, in the y-axis direction and the z-axis direction, respectively. With this configuration, the relative position of the substrate 190 with respect to the metal case 111 in the y-axis direction and the relative position in the z-axis direction can be adjusted, respectively.

[0122] The end cap 113 can be understood as an end member fixed to one end of the metal case 111. The end cap 113 has a through hole 113a for passing a screw 340 through. The through hole 113a runs from one end face of the end cap 113 to the other end face along the longitudinal direction of the light curtain 1. A cable 120 may also be connected to the end cap 113.

[0123] The front cover 130 is mounted on the front of the housing 110 so as to transmit light from the light-emitting element 160 and intersect with multiple optical axes Oax.

[0124] The circuit board 190 is placed in a sealed space CS formed by the housing 110 and the front cover 130. The circuit board 190 is equipped with a light-emitting element 160 and an AC discharge unit 350.

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

[0126] The AC discharge section 350 performs capacitor coupling between the metal case 111 and the grounding wiring 192 of the substrate 190 via conductive screws 340. Therefore, the noise immunity of the light curtain 1 is enhanced. The AC discharge section 350 will be described in more detail later.

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

[0128] The packing 362 is sandwiched between the seating surface of the screw 340 and the end cap 113 to prevent dust and liquid from entering the sealed space CS from the outside.

[0129] <AC discharge section> Figure 15 shows an example configuration of the AC discharge section 350. The AC discharge section 350 in this example configuration includes a capacitor 351 and a conductive member 352.

[0130] The capacitor 351 is mounted on the circuit board 190. The first terminal of the capacitor 351 is electrically connected to the grounding wire 192 laid on the circuit board 190. The second terminal of the capacitor 351 is electrically connected to the conductive member 352 via the wiring laid on the circuit board.

[0131] The conductive member 352 contacts the screw 340, thereby creating electrical conductivity between the second end of the capacitor 351 and the screw 340. The conductive member 352 will be described in more detail later.

[0132] As mentioned above, screw 340 is electrically connected to the metal case 111. More specifically, screw 340 is electrically connected to the metal case 111 by fastening it to a threaded hole 111d, which is, for example, made of metal and is not insulated. The metal case 111 can be understood as a ground.

[0133] Through the series of electrical connections described above, capacitor coupling is achieved between the metal case 111 and the grounding wire 192 via the conductive screw 340. Therefore, AC signals such as noise are discharged from the grounding wire 192 to the metal case 111, thereby improving the noise immunity of the light curtain 1.

[0134] Furthermore, this configuration allows for miniaturization of the metal case 111 and facilitates stable conductivity compared to the conventional configuration where electrical conductivity is achieved at the cut end face of the metal case 111.

[0135] Figure 16 shows an example configuration of the conductive member 352. As shown in this figure, the conductive member 352 may be a conductive leaf spring, a so-called shield finger, that contacts the screw 340 inserted into the through hole 113a of the end cap 113 while being biased.

[0136] Although not shown again in the diagram, the fixing structure between the metal case 111 and the end cap 112 is basically the same as described above.

[0137] <Case Outer Dimensions> Figure 17 is a cross-sectional view showing the external shape of the housing 110 (particularly the metal case 111). In this figure, the cross-section is depicted when the housing 110 is cut perpendicularly at any position in the longitudinal direction, i.e., the cross-section zy perpendicular to the longitudinal direction. As shown in this figure, the housing 110 has side wall portions Pa and Pb and arc portions Pc to Pf.

[0138] The side wall portions Pa and Pb are approximately parallel to the optical axis Oax in a zy-section view of the housing 110. The side wall portions Pa and Pb are provided so as to be symmetrical with respect to the optical axis Oax. The arc portions Pc to Pf are each part of the circumference C in a zy-section view of the housing 110. The arc portions Pc and Pd are provided so as to be symmetrical with respect to the optical axis Oax. The arc portions Pe and Pf are provided so as to be symmetrical with respect to the optical axis Oax. The arc portions Pc and Pd are provided in front of the side wall portions Pa and Pb, that is, on the surface side of the housing 110. The arc portions Pe and Pf are provided behind the side wall portions Pa and Pb, that is, on the rear side of the housing 110.

[0139] In this configuration example, the housing 110 can be mounted by being directly gripped by the mounting brackets 2a, 2c, or 2e shown in Figure 8. Therefore, it is not necessary to form mounting grooves on the rear surface of the housing 110. In a typical configuration in which mounting grooves are formed on the housing 110, the strength of the rear portion where the mounting grooves are formed must be increased, which leads to an increase in the size of the housing 110. On the other hand, with the housing 110 in this configuration example, the constraint on the strength of the rear portion is eliminated, so a smaller size of the housing 110 can be achieved.

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

[0141] <Other variations> Furthermore, the various technical features disclosed herein can be modified in various ways, in addition to the embodiments described above, without departing from the spirit of the technical creation. In other words, the embodiments described above should be considered in all respects to be illustrative and not restrictive, and the technical scope of the present invention should be defined by the claims and understood to include all modifications that fall within the meaning and scope equivalent to the claims. [Explanation of symbols]

[0142] 1. Light Curtain (Multi-axis Photoelectric Sensor) 2, 2a, 2b, 2c, 2d, 2e fittings 3 bases 4. Series connection cable (an example of a function expansion unit) 4a Protrusion 5. Operation indicator light (an example of a function expansion unit) 5a Protrusion 5x light-emitting section 5y bottom 5z connection 100 floodlights 200 Receiver 110, 210 cabinets 111, 211 Metal Case 111a Main Unit 111b 1st protruding strip 111c 2nd protruding strip 111d Screw hole (through hole) 111d1 1st area (screw groove) 111d2 2nd area (locking groove) 112, 113, 212, 213 End caps (end members) 112x End Covers 112y opening 113a Through hole 120, 220 cables 121, 122 connectors 123 Insulation Connector 130 Front Cover 140, 240 indicator light 150 Bumper section 160, 161-166 Light-emitting elements 261-266 Photodetector 170, 270 Light source for indicator light 181, 281 Control circuits 182, 282 Communication Circuits 283 Output Circuit 284 Input Circuit 190 circuit boards 190a central area 190b End area 191 Light-shielding plate 192 Ground wiring 301, 311, 321, 331 connectors 302, 312, 322, 332 Guide section 313, 323, 333 packing 314, 334 DIP switches 340 Screw (Example of a fastening component) 350 AC discharge section 351 Capacitor 352 Conductive component (shield finger) 361, 362 Packing 370 Holder 371 Locking protrusion 372 Position adjustment mechanism a1, c1, e1 Base section b1, b2, d1, d2 main surface CS closed space Oax, Oax1~Oax6 Optical axis Pa, Pb side wall Pc, Pd, Pe, Pf arc section X optical axis intersection area

Claims

1. An optical element, one of a pair of light-emitting and light-receiving elements that form multiple optical axes along the longitudinal direction, is disposed inside a housing having a metal case extending in the longitudinal direction and an end member fixed to one end of the metal case, A cover that transmits light from the light-emitting element and is attached to the housing so as to intersect with the plurality of optical axes, A substrate is placed in a sealed space formed by the housing and the cover, on which one of the optical elements is mounted, The end member is fixed to the metal case, and a conductive fixing member is electrically connected to the metal case, An AC discharge unit that performs capacitor coupling between the metal case and the grounding wiring of the substrate via the aforementioned fixing member, Light curtains equipped with a light curtain.

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

3. The light curtain according to claim 2, wherein the conductive member has a conductive leaf spring that contacts the fixed member while being biased.

4. The light curtain according to any one of claims 1 to 3, comprising a first packing sandwiched between the metal case and the end member to prevent dust and liquid from entering the sealed space from the outside, and the fixing member provided inside the first packing.

5. The light curtain according to claim 4, wherein the fixing member is a screw, and the metal case has a screw hole formed therein for receiving the screw.

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

7. The light curtain according to claim 6, wherein the first region of the through hole has a groove for screwing with the screw, and the second region of the through hole is opened facing the substrate and functions as a locking groove for supporting a locking projection of a holder that supports the substrate.

8. The light curtain according to claim 7, wherein the metal case is provided with a pair of locking grooves on either side of the holder, the holder is provided with a pair of locking projections each supported by the pair of locking grooves, and the pair of locking projections have a position adjustment mechanism that adjusts the relative position of the substrate with respect to the metal case by pressing against the inner walls of the pair of locking grooves, respectively.

9. The light curtain according to claim 5, further comprising a second packing sandwiched between the seating surface 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, further comprising bumper portions that protrude beyond the outer surface of the cover along a plurality of optical axes.

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