Safety switch

Abstract

To downsize a safety switch having a lock function using an electromagnet and a magnetized member.SOLUTION: A safety switch 100 includes a detection part having a magnetized member 301 on which an attracted surface is formed, for detecting that a movable actuator 300 is in a predetermined range, a safety signal output part 230 for outputting a safety signal on the basis of the detection result of the detection part, an electromagnet 201 on which an attracting surface is formed corresponding to the attracted surface, a lock input part 223 for receiving a lock instruction to lock a movement of the actuator, a drive control part 212 for driving the electromagnet so that the attracting surface of the electromagnet and the attracted surface of the actuator attract each other on the basis of the lock instruction received via the lock input part, and a mounting part 205 formed on the electromagnet to fix a switch body 200 to an installation site for the switch body.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a safety switch having a locking function using an electromagnet and a magnetizing member.

Background Art

[0002] In a factory or the like, a surrounding area around mechanical hazard sources such as a press device and a working robot is partitioned by partitioning members such as a safety fence. By stopping the operation of the mechanical hazard source when there is a possibility of a human body entering the surrounding area or when it is detected that a human body has actually entered the surrounding area, the human body can be protected from the mechanical hazard source.

[0003] The partitioning member is provided with an opening / closing part for a human body to enter and exit the surrounding area. A typical example of the opening / closing part is a door.

[0004] A safety switch is installed in the opening / closing part. The safety switch has a detection function for detecting the open / closed state of the opening / closing part.

[0005] A safety system including the safety switch stops the mechanical hazard source when the opening / closing part changes from the closed state to the open state.

[0006] When there is no possibility of a human body entering the surrounding area or when it is confirmed that no human body has actually entered the surrounding area and that state is maintained, the safety system is in a "safe state". In the "safe state", an ON signal is output as a safety signal from the safety switch, and the mechanical hazard source operates.

[0007] And when the opening / closing part changes to the open state from the "safe state" and the surrounding area is opened, the safety system is no longer in the "safe state", so an OFF signal is output as a safety signal from the safety switch, and the mechanical hazard source stops.

[0008] Furthermore, in the safety system, once an OFF signal is output as a safety signal from the safety switch, the mechanical hazard will not reactivate simply by closing the opening / closing mechanism. The mechanical hazard will only reactivate when a separate reset signal is input. The reason a separate reset signal is required is that once the surrounding area is opened, even if the opening / closing mechanism is subsequently closed, it cannot be confirmed that there is no possibility of a human body entering the surrounding area, or that a human body has not entered the surrounding area.

[0009] Some safety switches not only have a detection function to detect the open / closed state of the opening / closing part, but also a locking function to restrict the opening of the opening / closing part (see, for example, Patent Document 1). If an operator accidentally opens the opening / closing part from the closed state, the mechanical hazard stops, which reduces the production efficiency of factories, etc. The locking function of the safety switch can prevent operators from accidentally opening the opening / closing part from the closed state, thus contributing to improved production efficiency in factories, etc.

[0010] One example of the above-mentioned locking mechanism is one that uses an electromagnet and a magnetizing element. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2016-510382 (Figure 6B) [Overview of the project] [Problems that the invention aims to solve]

[0012] A challenge with safety switches that have a locking function is that they are inevitably larger than safety switches that do not have a locking function. Furthermore, in conventional safety switches with a locking function that use electromagnets and magnetizing elements, the shape of the electromagnet has not been sufficiently considered, and there is room for improvement in the shape of the electromagnet.

[0013] In view of the above problems, the present invention aims to provide a safety switch that has a locking function using an electromagnet and a magnetizing member and can be miniaturized. [Means for solving the problem]

[0014] A safety switch that solves the above problems includes a detection unit that has a magnetized member on which an adsorption surface is formed, detects that a movable actuator is within a predetermined range, outputs a safety signal output unit that outputs a safety signal based on the detection result by the detection unit, has an electromagnet on which an adsorption surface corresponding to the adsorption surface is formed, has a lock input unit that receives a lock instruction to lock the movement of the actuator, has a drive control unit that drives the electromagnet so that the adsorption surface of the electromagnet and the adsorption surface of the actuator are attracted to each other based on the lock instruction received via the lock input unit, and has a mounting part formed on the electromagnet for fixing the switch body to the installation location of the switch body.

[0015] Further features, elements, steps, advantages, and characteristics will become clearer from the embodiments for carrying out the invention and the accompanying drawings that follow. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a safety switch that has a locking function using an electromagnet and a magnetizing member, and that can be miniaturized. [Brief explanation of the drawing]

[0017] [Figure 1] Diagram showing an example of the application of a safety switch. [Figure 2] Perspective view showing an example of a switch unit. [Figure 3] Perspective view showing an example of the core and yoke sections. [Figure 4] Front view of an electromagnet [Figure 5] Perspective view showing an example of an actuator. [Figure 6] Perspective view showing another example of the switch body. [Figure 7] Figure showing the density distribution of magnetic field lines in an electromagnet [Figure 8] Figure showing the functional blocks of a safety switch

Embodiments for Carrying Out the Invention

[0018] <Application Example of the Safety Switch> FIG. 1 is a diagram showing an application example of the safety switch. In FIG. 1, a guard 400 surrounding a mechanical hazard source such as a machine tool is illustrated. The guard 400 is an example of safety protection by isolation, and in FIG. 1, a part of the enclosure box having an isolation wall (particularly around the door where the safety switch is provided) is depicted as viewed from the inside of the enclosure box. However, the depiction in FIG. 1 is merely an example, and it can also be understood by replacing the isolation wall in FIG. 1 with an iron fence or the like.

[0019] In FIG. 1, the X direction, Y direction, and Z direction that are perpendicular to each other are illustrated. The X direction, Y direction, and Z direction all correspond to the arrangement posture of the safety switch 100 as described later.

[0020] The guard 400 includes a slide-type door 401 as a movable guard that can be opened and closed. The main body portion of the door 401 may be made of a transparent resin or tempered glass, etc. So that the moving direction of the door 401 when the door 401 transitions from the closed state to the open state becomes the X direction in FIG. 1 , the safety switch 100 is arranged. When the safety switch 100 is arranged in this way, the moving direction of the door 401 when the door 401 transitions from the open state to the closed state becomes the direction opposite to the X direction (-X direction) in FIG. 1.

[0021] The safety switch 100 includes a switch body 200 and an actuator 300.

[0022] The switch body 200 of the safety switch 100 is fixed to a support member 403 which is fixed to the lower part of the door frame 402 of the guard 400. Thus, it is desirable to install the switch body 200 on a fixed door frame 402 rather than on a door 401 that can be opened and closed (moved). In the depiction in Figure 1, the screws for fixing the support member 403 to the door frame 402 of the guard 400 are omitted.

[0023] On the other hand, the actuator 300 of the safety switch 100 is fixed to a support member 404 which is fixed to the lower side of the door 401. In the depiction in Figure 1, the screws for fixing the support member 404 to the door 401 are omitted. Therefore, the actuator 300 is fixed so that it is relatively movable relative to the switch body 200.

[0024] Furthermore, the safety switch 100, as a safety function contributing to the safety system, detects whether the actuator 300 is within a predetermined range relative to the switch body 200, and outputs the detection result as a safety signal. The safety signal is also called an OSSD (Output Signal Switching Device).

[0025] For example, when the door 401 of the guard 400 is closed, the RFID (Radio Frequency Identification) of the actuator 300 installed on the door 401 comes into close proximity to the detection unit (antenna coil) of the switch body 200 installed on the door frame 402. At this time, the switch body 200 detects that the actuator 300 is within a predetermined range relative to the switch body 200, based on the RFID being identified by the detection unit, and indirectly detects that the door 401 is closed. In this way, the safety switch 100 is arranged to detect the open / closed state of the door 401 corresponding to itself.

[0026] When door 401 is open, the operation of the mechanical hazard surrounded by guard 400 is prohibited. On the other hand, when door 401 is closed, the operation of the machine tool surrounded by guard 400 may be permitted (i.e., one of the conditions for permission to operate is met).

[0027] Thus, the safety switch 100 is a device for protective measures against mechanical hazards. In particular, the safety switch 100 is a type of safety protection that involves stopping. In this type, the surrounding area, which is the area around the hazard, is demarcated, and when a state is detected where there is a possibility of human intrusion into the surrounding area, or when a human intrusion has occurred, the operation of the mechanical hazard is stopped. Specifically, in a safety system equipped with the safety switch 100, the mechanical hazard is stopped when the door 401 changes from a closed state to an open state.

[0028] In other words, as long as certain conditions are met, such as no human body entering the surrounding area, and this state is maintained by closing door 401, the system is considered "safe," and an ON signal is output from the safety switch 100 as an OSSD, activating the mechanical hazard. On the other hand, when door 401 moves from the "safe state" and the surrounding area is opened, an OFF signal is output from the safety switch 100 as an OSSD, stopping the mechanical hazard.

[0029] In the overall safety system, once an OFF signal is output from the safety switch 100, even if the door 401 itself moves to the closed position, the mechanical hazard will not reactivate, and a separate reset signal will be issued. It will be reactivated by force. This is because once door 401 is opened, even if door 401 is subsequently closed, it is impossible to confirm that no human body has entered the surrounding area.

[0030] In addition to the safety functions described above, the safety switch 100 also has a locking function to restrict the opening of the door 401.

[0031] For example, the safety switch 100 detects that the door 401 is closed by detecting that the actuator 300 is within a predetermined range relative to the switch body 200, and then drives the electromagnet of the switch body 200 when it receives a lock input output from an external device. At this time, the iron plate of the actuator 300 is magnetized. As a result, the electromagnet is attracted to the iron plate, and the opening of the door 401 is restricted. The safety switch 100 may also be configured not to release the lock on the door 401 unless a specific signal is input from the external device.

[0032] If the safety switch 100 has a locking function, it is possible to prevent malfunctions such as the mechanical hazard being shut off based on the OSSD output every time the worker accidentally opens the door 401.

[0033] Thus, the locking function of the safety switch 100 can be understood as an auxiliary function (=non-safety function) for maintaining the smooth operation of the mechanical hazard. In other words, the safety function of the safety system is realized solely through the OSSD output of the safety switch 100.

[0034] <Mechanical structure of safety switches> Figure 2 is a perspective view showing an example of the switch body 200. The X, Y, and Z directions in Figure 2 are orthogonal to each other. The X direction in Figure 2 is the same as the X direction in Figure 1. The Y direction in Figure 2 is the same as the Y direction in Figure 1. The Z direction in Figure 2 is the same as the Z direction in Figure 1.

[0035] The X direction corresponds to the orientation of the safety switch 100, or more specifically, the orientation of the switch body 200, which is part of the safety switch 100. Specifically, the X-axis direction is the axial direction parallel to the normal direction of the adsorption surface 209A. One of the X-axis directions, the X direction, is the direction from the coil provided on the electromagnet 201 toward the adsorption surface 209A. The other X-axis direction, the -X direction, is the direction opposite to the X direction.

[0036] The Y direction also corresponds to the orientation of the safety switch 100, or more specifically, the orientation of the switch body 200, which is part of the safety switch 100. Specifically, the Y-axis direction is the axial direction along the longitudinal direction of the switch body 200. One direction of the Y-axis direction, the -Y direction, is the direction in which the terminal 203 protrudes. The other direction of the Y-axis direction, the Y direction, is the direction opposite to the -Y direction.

[0037] The Z-direction also corresponds to the orientation of the safety switch 100, or more specifically, the orientation of the switch body 200, which is part of the safety switch 100. The Z-axis direction is perpendicular to the X-axis and Y-axis directions. The Z-axis direction includes the Z-direction and the -Z-direction, which is the direction opposite to the Z-direction.

[0038] For the sake of explanation, the following will be defined as follows: X direction forward, -X direction backward, Y direction upward, -Y direction downward, Z direction right, and -Z direction left. However, this example does not limit the orientation of the safety switch 100.

[0039] The switch body 200 comprises an electromagnet 201, a resin housing 202, and terminals 203. The electromagnet 201 is located at the upper front of the resin housing 202. The upper part of the resin housing 202 is approximately rectangular in shape. The back (rear surface) of the electromagnet 201 is in contact with and connected to the upper front of the resin housing 202. The suction surfaces 209A and 209B of the electromagnet 201 and the mounting portion 205 are not covered by the resin housing 202 and are exposed to the outside.

[0040] The lower part of the resin housing 202 is approximately rectangular in shape, similar to the upper part of the resin housing 202. The lower rear surface of the resin housing 202 forms a coplanar plane with the upper rear surface of the resin housing 202. The lower front surface of the resin housing 202 is located further forward than the upper front surface of the resin housing 202. The bottom surface of the electromagnet 201 is in contact with the lower upper surface of the resin housing 202.

[0041] Terminal 203 protrudes downward from the lower bottom surface (bottom surface) of the resin housing 202. A cable connector is connected to terminal 203. This cable electrically connects the switch body 200 to an external device. Terminal 203 constitutes an output section that outputs a safety signal.

[0042] A pair of indicator lights 204L and 204R are provided on the lower front of the resin housing 202, separated to the left and right. The letters L and R following the reference number are used to distinguish multiple identical or similar components. When describing aspects common to multiple components, the letters L and R are omitted.

[0043] The resin housing 202 houses a detection unit that detects whether the actuator 300 is within a predetermined range relative to the switch body 200, a safety signal output unit that outputs a safety signal based on the detection result from the detection unit, and a control unit that supplies a drive signal to the electromagnet 201, etc.

[0044] The electromagnet 201 has a mounting portion 205 for fixing the switch body 200 to the installation location of the switch body 200 (for example, the door frame 402 shown in Figure 1). In the example shown in Figure 2, the mounting portion 205 is a screw hole extending in the left-right direction. Also in the example shown in Figure 2, two mounting portions 205 are provided on the right side of the electromagnet 201, and similarly, two mounting portions 205 are provided on the left side of the electromagnet 201.

[0045] The switch body 200 may be directly attached to the installation location of the switch body 200 by the mounting portion 205, or it may be indirectly attached to the installation location of the switch body 200 by being attached to the support member 403 by the mounting portion 205, as shown in the example in Figure 1.

[0046] When the switch body 200 is directly attached to the installation location of the switch body 200, it is desirable that the installation location of the switch body 200 be a metal material. When the switch body 200 is attached to an intermediary member such as a support member 403, it is desirable that the intermediary member be a metal material. In other words, it is desirable that the electromagnet 201 be attached to a metal material by the mounting portion 205. When such a configuration is adopted, heat dissipation of the electromagnet 201, which generates heat when driven, can be promoted.

[0047] By forming a mounting portion 205 on the electromagnet 201, the housing of the switch body 200 no longer plays a role in fixing the switch body 200 to its installation location. Therefore, it is no longer necessary to enlarge the housing of the switch body 200 to meet the required fixing strength and positional accuracy. As a result, the switch body 200 and, consequently, the safety switch 100 can be made smaller.

[0048] Furthermore, the formation of the mounting portion 205 on the electromagnet 201 prevents the attractive force applied to the electromagnet 201 from being applied to the housing of the switch body 200 due to the locking function of the safety switch 100. Therefore, the mechanical strength of the housing of the switch body 200 does not need to be relatively low. In other words, the housing of the switch body 200 does not have to be a metal housing, and may be a resin housing 202 as shown in the example in Figure 2. If the detection unit of the switch body 200 is a detection unit that uses electromagnetic waves, then when a resin housing 202 is used as the housing of the switch body 200, the detection sensitivity of the detection unit will be improved compared to when a metal housing is used as the housing of the switch body 200.

[0049] The electromagnet 201 comprises a cylindrical core 206, a bobbin 207 provided radially outside the core 206 around which a coil is wound, and a yoke 208 provided radially outside the bobbin 207. When the electromagnet 201 is driven, current flows through the coil wound around the core 206, generating a magnetic field for attracting the electromagnet 201 to the iron plate 301 of the actuator 300 (see Figure 5). The core 206 and the yoke 208 are both magnetic materials. It is desirable that the winding direction D1 of the antenna coil 263 (see Figures 7 and 8) housed in the resin housing 202 and the winding direction D2 of the coil wound around the bobbin 207 of the electromagnet 201 are different. This makes the antenna coil 263 (see Figures 7 and 8) less susceptible to the influence of magnetic field lines from the electromagnet 201, thereby improving the detection accuracy of the detection unit that detects whether the actuator is within a predetermined range relative to the switch body 200.

[0050] The electromagnet 201 has suction surfaces 209A and 209B that can be attracted to the iron plate 301 of the actuator 300 (see Figure 5). Suction surface 209A is the front surface of the core portion 206. Suction surface 209B is the foremost surface of the yoke portion 208. The front-rear position of suction surface 209A and suction surface 209B are the same. Suction surface 209A is circular, and suction surface 209B is an annular shape with a larger diameter than the circular surface and is concentric with the circular surface.

[0051] The core portion 206 and the yoke portion 208 may be a single integrated structure, as shown in the example in Figure 3, or they may be separate parts, as in the example shown in Figure 3.

[0052] Figure 4 is a front view of the electromagnet 201 described above. The upper right corner of the yoke portion 208 is a protruding portion P1 that protrudes outward from the suction surfaces 209A and 209B when viewed from the front. The lower right corner, lower left corner, and upper left corner of the yoke portion 208 are also the above-mentioned protruding portions P1. In other words, the electromagnet 201 is equipped with protruding portions P1 that protrude outward from the suction surfaces 209A and 209B when viewed from the front.

[0053] The front surface of each protrusion P1 is located behind the suction surfaces 209A and 209B. That is, when the suction surfaces 209A and 209B are attached to the iron plate 301 of the actuator 300 (see Figure 5), each protrusion P1 is separated from the iron plate 301 of the actuator 300 (see Figure 5) in the direction normal to the suction surfaces 209A and 209B (front-to-back direction).

[0054] If the shape of the yoke portion 208 is designed such that the magnetic field lines are in an ideal state when the suction surfaces 209A and 209B are attracted to the iron plate 301 of the actuator 300 (see Figure 5), then the density of magnetic field lines on the suction surface 209B will be approximately the same as the density of magnetic field lines in the central part of the suction surface 209A.

[0055] On the other hand, if each protrusion P1 is provided, and the front surface of each protrusion P1 forms a virtually identical plane with the adsorption surfaces 209A and 209B, then the magnetic field lines spread unnecessarily in the yoke portion 208. As a result, the density of magnetic field lines on the adsorption surface 209B becomes significantly smaller than the density of magnetic field lines in the central part of the adsorption surface 209A, and the adsorption force decreases. However, if the front surface of each of the above protrusions is located behind the adsorption surfaces 209A and 209B, as in the example shown in Figures 2 and 3, then the magnetic field lines when the adsorption surfaces 209A and 209B are adsorbed to the iron plate 301 of the actuator 300 (see Figure 5) can be brought closer to the ideal state, and the density of magnetic field lines on the adsorption surface 209B can be brought closer to the magnetic field lines in the central part of the adsorption surface 209A. It can be made to approach the density of lines. Therefore, the decrease in adsorption force can be suppressed.

[0056] A mounting portion 205 is provided on each protrusion P1. By providing the mounting portion 205 on the protrusion P1, interference between the mounting portion 205 and the coil of the electromagnet 201 (the coil wound around the bobbin 207) can be suppressed. This is because, when the adsorption surfaces 209A and 209B are viewed from the front, the mounting portion 205 is located outside the bobbin 207 and, consequently, the coil of the electromagnet 201.

[0057] Unlike the examples shown in Figures 2 to 4, even if the mounting portion 205 is, for example, a screw hole extending from front to back or a screw hole extending from top to bottom, if the mounting portion 205 is provided on the above-mentioned protruding portion, interference between the mounting portion 205 and the coil of the electromagnet 201 (the coil wound around the bobbin 207) can be suppressed.

[0058] In the example shown in Figures 2 to 4, the ends E1 of two mounting portions 205R are provided on the right side surface F1 of the electromagnet 201, which corresponds to the outer circumferential surface surrounding the central axis intersecting the centers of the suction surfaces 209A and 209B. Similarly, the ends E2 of the remaining two mounting portions 205L are provided on the left side surface F2 of the electromagnet 201, which also corresponds to the outer circumferential surface surrounding the central axis intersecting the centers of the suction surfaces 209A and 209B. With this configuration, it is possible to avoid providing mounting portions on the back (rear) surface of the electromagnet 201. This makes it possible to use, for example, the back (rear) surface of the electromagnet 201 as a contact surface with the resin housing 202.

[0059] The resin housing 202 houses a detection unit that detects whether the actuator 300 is within a predetermined range relative to the switch body 200. To increase the detection sensitivity of the detection unit, it is desirable to position the detection unit as close to the actuator 300 as possible. Therefore, it is desirable to position the frontmost part of the resin housing 202 slightly behind the frontmost part of the electromagnet 201, and to position the detection unit as close to the frontmost part of the resin housing 202 as possible. The reason for positioning the frontmost part of the resin housing 202 slightly behind the frontmost part of the electromagnet 201 is that if the resin housing 202 contacts the actuator 300 before the electromagnet 201 when closing the door, the electromagnet 201 may not be attracted to the iron plate 301 (see Figure 5) of the actuator 300.

[0060] Depending on the shape of the components housed in the resin housing 202, the front-to-back dimension of the resin housing 202 may be larger than the front-to-back dimension of the electromagnet 201. In such cases, if the frontmost surface of the electromagnet 201 and the frontmost surface of the resin housing 202 are made to form a virtually identical plane, the rear surface of the resin housing 202 will be located behind the rear surface of the electromagnet 201. Therefore, by positioning a portion of the resin housing 202 behind the electromagnet 201 and using the rear surface of the electromagnet 201 as a contact surface with the resin housing 202, the space behind the electromagnet 201 can be effectively utilized.

[0061] In the example shown in Figure 1, two mounting parts 205L are used to fix the switch body 200 to the door frame 402. On the other hand, if the switch body 200 is reversed vertically compared to the example shown in Figure 1, two mounting parts 205R are used to fix the switch body 200 to the door frame 402.

[0062] The two mounting sections 205L are each provided on separate protrusions (the upper left corner and the lower left corner of the yoke section 208). This allows for a longer distance between the two mounting sections 205L, resulting in more stable fixing using the two mounting sections 205L.

[0063] The two mounting portions 205R are each provided on separate protrusions (the upper right corner and the lower right corner of the yoke portion 208). This increases the distance between the two mounting portions 205R. This allows for stable fixing using the two mounting parts 205R.

[0064] Figure 5 is a perspective view showing an example of an actuator 300. The actuator 300 comprises a steel plate 301, a metal housing 302, and mounting parts 303 and 304. The steel plate 301 is a magnetized member that is magnetized by an electromagnet 201. The attracting surfaces 209A and 209B of the electromagnet 201 correspond to the attracting surfaces formed on the steel plate 301, and the electromagnet 201 is attracted to the steel plate 301. The metal housing 302 houses a communication unit 310 (see Figure 8), etc. The mounting parts 303 and 304 are used to fix the actuator 300 to its installation location (for example, the door 401 shown in Figure 1).

[0065] <Another example of the Switch console> Figure 6 is a perspective view showing another example of the switch body 200. In the other example of the switch body 200 shown in Figure 6, the same parts as in the example of the switch body 200 shown in Figure 2 are denoted by the same reference numerals. The actuator of the safety switch equipped with the other example of the switch body 200 shown in Figure 6 is mainly installed on hinged doors (opening doors) rather than sliding doors.

[0066] The X, Y, and Z directions in Figure 6 are orthogonal to each other. The X, Y, and Z directions in Figure 6 are unrelated to the X, Y, and Z directions in Figure 1.

[0067] In Figure 6, the X direction corresponds to the orientation of the safety switch 100, or more specifically, the orientation of the switch body 200, which is part of the safety switch 100. Specifically, the X-axis direction is the axial direction parallel to the normal direction of the adsorption surface 209A. One of the X-axis directions, the X direction, is the direction from the coil provided on the electromagnet 201 toward the adsorption surface 209A. The other X-axis direction, the -X direction, is the direction opposite to the X direction.

[0068] The Y direction in Figure 6 also corresponds to the orientation of the safety switch 100, or more specifically, the orientation of the switch body 200, which is part of the safety switch 100. Specifically, the Y-axis direction is the axial direction along the protruding direction of the protruding portion P2 provided on the switch body 200. One direction of the Y-axis is the Y direction in which the protruding portion P2 protrudes. The other direction of the Y-axis is the -Y direction, which is the direction opposite to the Y direction.

[0069] The Z-direction in Figure 6 also corresponds to the orientation of the safety switch 100, or more specifically, the orientation of the switch body 200, which is part of the safety switch 100. The Z-axis direction is perpendicular to the X-axis and Y-axis directions. The Z-axis direction includes the Z-direction and the -Z-direction, which is the direction opposite to the Z-direction.

[0070] For the sake of explanation, the following will refer to the X direction as forward, the -X direction as backward, the Y direction as upward, the -Y direction as downward, the Z direction as right, and the -Z direction as left. However, this example does not limit the installation direction of the switch body 200 in the alternative example shown in Figure 6.

[0071] The electromagnet 201 is provided with a projection P2 that protrudes outward (upward) relative to the suction surfaces 209A and 209B when viewed from the front. The upper surface of the projection P2 is provided with the ends of two mounting portions 205 along a central axis AX1 that intersects the centers of the suction surfaces 209A and 209B and extends in the front-rear direction. In the example shown in Figure 6, the mounting portion 205 is a screw hole that extends in the vertical direction.

[0072] In order to reduce the external dimensions of the switch body 200 in the alternative example shown in Figure 6 when the suction surfaces 209A and 209B are viewed from the front, the winding direction of the antenna coil 263 (see Figures 7 and 8) housed in the resin housing 202 and the winding direction of the coil wound around the bobbin 207 of the electromagnet 201 must be the same direction (front-to-back direction). Therefore, the switch in the alternative example shown in Figure 6 In the main unit 200, the winding direction D3 of the antenna coil 263 (see Figures 7 and 8) housed in the resin housing 202 and the winding direction D4 of the coil wound around the bobbin 207 of the electromagnet 201 are in the front-to-back direction.

[0073] However, if the winding direction of the antenna coil 263 (see Figures 7 and 8) and the winding direction of the coil wound around the bobbin 207 of the electromagnet 201 are the same, the antenna coil 263 may be affected by the electromagnet 201, which generates a stronger magnetic flux, potentially worsening the detection accuracy of the detection unit.

[0074] In the alternative switch body 200 shown in Figure 6, the deterioration of the detection accuracy of the detection unit is suppressed by providing the antenna coil 263 in the position shown in Figure 7. Specifically, when the suction surfaces 209A and 209B are viewed from the front, the suction surface 209A is circular, the distance between the antenna coil 263 and the center of the circle in the radial direction of the circle is less than or equal to the distance between the tip of the protrusion P2 and the center of the circle in the radial direction of the circle, and the antenna coil 263 is provided such that its position in the circumferential direction of the circle coincides with the position of the protrusion P2 in the circumferential direction of the circle. In other words, the antenna coil 263 is provided inside the sector drawn by the dotted line in Figure 7.

[0075] Figure 7 shows the density distribution of magnetic field lines in the electromagnet 201. The first to eighth regions R1 to R8 are classified according to the magnitude of the magnetic field line density, with larger ordinal numbers preceding the region names indicating regions with lower magnetic field line density. Due to the influence of the protrusion P2, the magnetic flux density is lower in the vicinity of the protrusion P2. Therefore, by providing the antenna coil 263 in the vicinity of the protrusion P2 (specifically, inside the sector depicted by the dotted line in Figure 7), the deterioration of the detection accuracy of the detection unit is suppressed.

[0076] The switch body 200 in another example shown in Figure 6 has the features of having a mounting portion 205 on the protruding portion P2 and having an antenna coil 263 in the vicinity of the protruding portion P2. Note that the features of having a mounting portion 205 on the protruding portion P2 and the features of having an antenna coil 263 in the vicinity of the protruding portion P2 are not directly related to each other. Therefore, as a modification of the switch body 200, the switch body 200 may have a configuration in which the mounting portion 205 on the protruding portion P2 is not provided, but the antenna coil 263 is provided in the vicinity of the protruding portion P2.

[0077] <Electrical structure of safety switches> Figure 8 shows the functional block of the safety switch 100. In the safety switch 100 of the configuration example shown in Figure 8, the switch body 200 includes a control circuit 210, an input / output circuit 220, a switching device 230, an OSSD monitoring circuit 240, a power supply unit 250, a communication unit 260, a display unit 270, and an electromagnet 201. In this figure, the components of the switch body 200 that are located near the actuator 300 are grouped together on the left side of the block. Also, the components of the switch body 200 that are located far from the actuator 300 are grouped together on the right side of the block.

[0078] The control circuit 210 includes a first MCU (Micro Controller Unit) 211 and a second MCU 212. The input / output circuit 220 includes a first safety input section 221, a second safety input section 222, a lock input section 223, and an AUX (auxiliary) output section 224. The switching device 230, which serves as a safety signal output section, includes a first safety output section 231 and a second safety output section 232. The power supply section 250 includes a power supply circuit 251 and a power supply monitoring circuit 252. The communication section 260 includes an antenna coil 263 for exchanging wireless signals with the communication section 310 (Figure 8) of the actuator 300. The display section 270 includes an indicator light control section 271 and an indicator light 204. The lock input section 223 locks the movement of the actuator 300 relative to the switch body 200. Receives a lock instruction.

[0079] Furthermore, in the safety switch 100 of the configuration example shown in Figure 8, the actuator 300 comprises a communication unit 310 and a metal plate 301. The communication unit 310 includes an antenna coil 311 and a response circuit 312.

[0080] The first MCU211 and the second MCU212 monitor each other by communicating with one another. The first MCU211 and the second MCU212 are connected to the antenna coil 263.

[0081] The first MCU 211 drives the antenna coil 263 and transmits a radio signal from the antenna coil 263 to the communication unit 310 (particularly the antenna coil 311) of the actuator 300. The communication unit 310 may be a radio tag (RF-ID tag).

[0082] The response circuit 312 operates using the induced current generated in the antenna coil 311 as its power source. The response circuit 312 also demodulates the radio signal received by the antenna coil 311 to obtain information, and then transmits a radio signal (response signal) via the antenna coil 311.

[0083] The first MCU 211 and the second MCU 212 each receive the radio signal (response signal) transmitted from the antenna coil 311 of the actuator 300 via the antenna coil 263.

[0084] The first MCU 211 includes a measuring unit 211a, a demodulation unit 211b, and a safety determination circuit 211c. The second MCU 212 also includes a measuring unit 212a, a demodulation unit 212b, a safety determination circuit 212c, and a display control unit 212d. The second MCU 212 functions as a drive control unit that controls the driving of the electromagnet 201, and controls the driving of the electromagnet 201 based on a lock instruction received via the lock input unit 223.

[0085] Measurement units 211a and 212a each measure the strength of the radio signal (response signal) received via the antenna coil 263, and estimate the distance d between the antenna coil 263 of the switch body 200 and the antenna coil 311 of the actuator 300 (and consequently, the distance from the switch body 200 to the actuator 300) based on the measurement results. The antenna coil 263 is included in the detection unit that detects whether the actuator 300 is within a predetermined range relative to the switch body 200. Alternatively, the strength of the radio signal may be used directly to detect the position of the actuator 300 instead of the distance d between the coils.

[0086] Furthermore, the method for detecting whether the actuator 300 is within a predetermined range relative to the switch body 200 is not limited to the method using the antenna coil 263 described above. For example, a physical switch may be provided on the switch body 200, and a detection principle may be adopted in which the physical switch is pressed by a protruding member or the like provided on the actuator 300 when the door is closed and the actuator 300 approaches the switch body 200.

[0087] It is desirable that the antenna coil 263 has a different winding direction than the coil wound around the bobbin 207 of the electromagnet 201. This makes the antenna coil 263 less susceptible to the influence of magnetic field lines from the electromagnet 201, thereby improving the detection accuracy of the detection unit.

[0088] The demodulation units 211b and 212b each demodulate the information carried by the radio signal (response signal) received via the antenna coil 263, and identify the actuator 300 based on this information. This information may include unique identification information (ID information).

[0089] The safety determination circuit 211c of the first MCU 211 determines whether the distance d between coils measured by the measurement unit 211a is less than or equal to the threshold dth, and transmits the determination result to the second MCU 212. Similarly, the safety determination circuit 212c of the second MCU 212 determines whether the distance d between coils measured by the measurement unit 212a is less than or equal to the threshold dth, and transmits the determination result to the first MCU 211. Then, if the determination result of the safety determination circuits 211c and 212c matches the determination result of the other (both determine that the distance d between coils is less than or equal to the threshold dth), they determine that the actuator 300 is within a predetermined range relative to the switch body 200 (door closed state).

[0090] In the input / output circuit 220, the first safety input section 221 and the second safety input section 222 are input circuits for cascading multiple safety switches 100 in serial order. For example, the first safety input section 221 and the second safety input section 222 are connected to the first safety output section 231 and the second safety output section 232 of another safety switch 100 located upstream, respectively.

[0091] The first MCU 211 is connected to the first safety input unit 221. When an ON signal is input through the first safety input unit 221, the first MCU 211 controls the first safety output unit 231 based on the proximity state of the actuator 300 (= door open / closed state) and the locked state of the electromagnet 201. On the other hand, when an OFF signal is input through the first safety input unit 221, the first MCU 211 causes the first safety output unit 231 to output an OFF signal, regardless of the proximity state of the actuator 300 and the locked state of the electromagnet 201.

[0092] Similarly, the second MCU 212 is connected to the second safety input unit 222. When an ON signal is input through the second safety input unit 222, the second MCU 212 controls the second safety output unit 232 based on the proximity state of the actuator 300 and the locked state of the electromagnet 201. On the other hand, when an OFF signal is input through the second safety input unit 222, the second MCU 212 causes the second safety output unit 232 to output an OFF signal, without relying on the proximity state of the actuator 300 and the locked state of the electromagnet 201.

[0093] This makes it possible to cascade multiple safety switches 100. If any one of the safety switches 100 is not in a safe state, an OFF signal is output to the external device. Therefore, for example, if a fence surrounding a mechanical hazard has multiple doors, the mechanical hazard cannot operate unless all doors are in a safe state. On the other hand, if all of the safety switches 100 are in a safe state, an ON signal is output to the external device.

[0094] The lock input unit 223 is connected, for example, to another safety switch 100 located upstream, and transmits upstream communication data (including lock input) and receives downstream communication data (including bundled AUX output data).

[0095] The AUX output unit 224 is connected, for example, to another safety switch 100 located downstream, and transmits downstream communication data (including bundled AUX output data) and receives upstream communication data (including lock input).

[0096] For example, the control circuit 210 generates downstream communication data based on the communication data received via the lock input unit 223 (=communication data that bundles the upstream AUX outputs) and the state of the safety switch 100 itself, and outputs this data from the AUX output unit 224.

[0097] The first safety output unit 231 and the second safety output unit 232 each output OSSD outputs (OSSD1_O and OSSD2_O) to another safety switch 100, for example, located downstream. To exert force.

[0098] For example, the control circuit 210 outputs OSSD outputs (OSSD1_O and OSSD2_O) from the first safety output unit 231 and the second safety output unit 232, respectively, based on the OSSD inputs (OSSD1_I and OSSD2_I) received via the first safety input unit 221 and the second safety input unit 222, and the proximity state of the actuator 300 (= detection result by the detection unit).

[0099] In the switching device 230, the first safety output section 231 and the second safety output section 232 may be configured as, for example, an open collector output circuit using a PNP type transistor. In this case, when the PNP type transistor is turned ON, the + side power supply is connected to the output terminal, so an ON signal (= high level) is output. On the other hand, when the PNP type transistor is turned OFF, the output terminal is grounded via a pull-down resistor, so an OFF signal (= low level) is output.

[0100] Furthermore, the first safety output section 231 and the second safety output section 232 can each be configured as open-collector output circuits using NPN transistors. In this case, the output logic levels will be reversed from those described above. Specifically, the ON signal will be at a low level, and the OFF signal will be at a high level.

[0101] The first safety output unit 231 and the second safety output unit 232 may each be connected to an OSSD monitoring circuit 240. The OSSD monitoring circuit 240 is connected to the first MCU 211 and the second MCU 212. The first MCU 211 monitors whether the operation of the second safety output unit 232 is normal through the OSSD monitoring circuit 240. The second MCU 212 monitors whether the operation of the first safety output unit 231 is normal through the OSSD monitoring circuit 240.

[0102] For example, the first safety output unit 231 and the second safety output unit 232 each periodically transition the output signal to OFF for a short period of time when outputting an ON signal. The OSSD monitoring circuit 240 determines that the OSSD is normal if it can detect a short period of OFF during the ON signal output period, and determines that the OSSD is not normal if it cannot detect a short period of OFF.

[0103] If the ON signal persists, it is due to a short circuit between the output terminal and the positive power supply. In this case, safety judgment circuits 211c and 212c output control signals to the first safety output unit 231 and the second safety output unit 232, respectively, to output an OFF signal. As a result, the normal of the first safety output unit 231 and the second safety output unit 232 will output an OFF signal.

[0104] The external device is only capable of permitting the operation of the mechanical hazard when both the first safety output unit 231 and the second safety output unit 232 are outputting an ON signal. In other words, the external device will not permit the operation of the mechanical hazard when at least one of the first safety output unit 231 or the second safety output unit 232 is outputting an OFF signal. The external device is configured not to react to the minute OFF period in the aforementioned ON signal.

[0105] In the power supply unit 250, the power supply circuit 251 is a DC-DC converter that receives an input voltage VCC (e.g., DC +24V) and a ground voltage GND (e.g., 0V) from an external source and generates a desired output voltage VREG (e.g., DC +10V, +5V, or +3.3V). The power supply circuit 251 supplies power to all parts of the switch body 200 (i.e., all circuits that require power).

[0106] By the way, if the input voltage VCC or output voltage VREG is not within the specified range, the first MCU211 and the second MCU212 may not operate properly. Therefore, power supply monitoring Circuit 252 determines whether the input voltage VCC and output voltage VREG are within a predetermined range, and outputs the determination result to the first safety output unit 231 and the second safety output unit 232.

[0107] When the first safety output unit 231 and the second safety output unit 232 receive a determination result indicating that the power supply circuit 251 is not operating normally, they each output an OFF signal, independent of the control signals output from the first MCU 211 and the second MCU 212, respectively.

[0108] Meanwhile, when the first safety output unit 231 and the second safety output unit 232 receive a determination result indicating that the power supply circuit 251 is operating normally, they output an ON signal or an OFF signal depending on the control signals output from the first MCU 211 and the second MCU 212, respectively.

[0109] The indicator light control unit 271, based on instructions from the control circuit 210 (for example, the indicator control unit 212d of the second MCU 212), turns the indicator light 204 on / off or on green / on red depending on the proximity state of the actuator 300 (= door open / closed state) and the lock / unlock state of the electromagnet 201.

[0110] Furthermore, the indicator light control unit 271 turns the indicator light 272 on / off or on green / red depending on the OSSD output, INPUT signal, and lock / unlock state. The OSSD output mentioned above refers to the output signals of the first safety output unit 231 and the second safety output unit 232, respectively.

[0111] The electromagnet 201 generates a magnetic force in response to a drive signal (drive current) supplied from the control circuit 210 (for example, the second MCU 212). At this time, the iron plate 301 (see Figure 5) of the actuator 300, which is close to the switch body 200, is magnetized. As a result, the door lock is achieved by the attractive force between the electromagnet 201 and the iron plate 301.

[0112] <Summary> The various embodiments described above will be summarized below.

[0113] For example, the safety switch disclosed herein has a configuration (first configuration) comprising: a detection unit having a magnetized member on which an adsorption surface is formed, for detecting that a movable actuator is within a predetermined range; a safety signal output unit that outputs a safety signal based on the detection result by the detection unit; an electromagnet on which an adsorption surface corresponding to the adsorption surface is formed; a lock input unit that receives a lock instruction to lock the movement of the actuator; a drive control unit that drives the electromagnet so that the adsorption surface of the electromagnet and the adsorption surface of the actuator are attracted to each other based on the lock instruction received via the lock input unit; and a mounting portion formed on the electromagnet for fixing the switch body to the installation location of the switch body.

[0114] In the safety switch with the first configuration described above, the electromagnet may have a protruding portion that protrudes outward from the suction surface when the suction surface is viewed from the front, and the mounting portion may be provided on the protruding portion (second configuration).

[0115] In the safety switch with the second configuration described above, the protrusion may be formed on the electromagnet such that when the adsorption surface and the surface to be adsorbed are adsorbed, the protrusion moves away from the magnetizing member in the direction normal to the adsorption surface (third configuration).

[0116] In a safety switch having any of the first to third configurations described above, the electromagnet may have an outer circumferential surface formed around a central axis intersecting the center of the adsorption surface, and the end of the mounting portion may be provided on the outer circumferential surface (fourth configuration).

[0117] In a safety switch having any of the first to fourth configurations described above, a resin housing may be provided to house the detection unit, the output unit, and the drive control unit, the electromagnet may be connected to the resin housing, and the suction surface and mounting portion formed on the electromagnet may be exposed (fifth configuration).

[0118] In the safety switch, which is the fifth configuration described above, there may also be a configuration (sixth configuration) that includes an output unit formed in the resin housing that outputs the safety signal.

[0119] In a safety switch having any of the above configurations 1 to 4, the detection unit includes a first coil for exchanging wireless signals to detect that the actuator is within a predetermined range, and the electromagnet includes a second coil that is driven by the drive control unit to generate a magnetic field for attracting the attracting surface of the electromagnet and the attracting surface of the actuator, and the first coil and the second coil may be configured to have different winding directions (configuration 7).

[0120] In the safety switch having the seventh configuration described above, there may also be a configuration (eighth configuration) in which a resin housing is provided to house the detection unit, and the suction surface and mounting portion formed on the electromagnet are exposed.

[0121] In a safety switch having any of the above configurations 1 to 6, the detection unit includes a first coil for exchanging wireless signals to detect that the actuator is within a predetermined range, and the electromagnet has a projection that protrudes outward from the suction surface when the suction surface is viewed from the front, the suction surface is circular when viewed from the front, the distance between the first coil and the center of the circle in the radial direction of the circle is less than or equal to the distance between the tip of the projection and the center of the circle in the radial direction of the circle, and the first coil is provided such that the position of the first coil in the circumferential direction of the circle coincides with the position of the projection in the circumferential direction of the circle (configuration 9).

[0122] In the safety switch with the ninth configuration described above, the electromagnet includes a second coil that is driven by the drive control unit to generate a magnetic field for attracting the attracting surface of the electromagnet to the attracting surface of the actuator, and the first coil and the second coil may be configured to have the same winding direction (the tenth configuration).

[0123] In a safety switch having any of the above configurations 1 to 10, the electromagnet may be attached to a metal member by the mounting portion (configuration 11).

[0124] In a safety switch having any of the above configurations 1 to 11, the drive control unit may be configured to drive the electromagnet so that the adsorption surface of the electromagnet and the surface to be adsorbed of the actuator are attracted to each other, based on the detection result from the detection unit and the lock instruction received via the lock input unit (configuration 12).

[0125] <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]

[0126] 100 Safety Switches 200 Switch consoles 201 Electromagnet 202 Resin housing 203 terminals 204, 204L, 204R indicator light Mounting section for 205, 205L, and 205R. 206 Core section 207 Bobbin 208 York Section 209A, 209B Adsorption surface 210 Control circuit 211 First MCU 211a Measuring part 211b Demodulation section 211c Safety judgment circuit 212 Second MCU 212a Measuring section 212b Demodulation section 212c Safety judgment circuit 212d Display Control Unit 220 Input / Output Circuits 221 First safety input section 222 Second safety input section 223 Lock Input Section 224 AUX output section 230 Switching Devices 231 First safety output section 232 Second safety output section 240 OSSD monitoring circuit 250 Power supply section 251 Power supply circuit 252 Power supply monitoring circuit 260 Communications Department 261 Transmitter Circuit 262 Receiving Circuit 263 Antenna coil 270 Display section 271 Indicator light control unit 300 Actuators 301 Iron Plate 302 Metal casing 303, 304 Mounting section 310 Communications Department 311 Antenna coil 312 Response Circuit 400 Guard 401 Door 402 Door frame 403, 404 Support members AX1 center axis D1~D4 Winding direction F1 Electromagnet, right side Left side of the F2 electromagnet Ends of mounting parts E1 and E2 P1, P2 protrusion R1~R8 1st~8th area

Claims

1. A detection unit that detects whether a movable actuator having a magnetized member on which an adsorption surface is formed is within a predetermined range, A safety signal output unit that outputs a safety signal based on the detection result from the detection unit, An electromagnet on which an adsorption surface corresponding to the surface to be adsorbed is formed, A lock input unit that receives a lock instruction to lock the movement of the actuator, A drive control unit drives the electromagnet so that the adsorption surface of the electromagnet and the surface to be adsorbed of the actuator are attracted to each other based on the lock instruction received via the lock input unit, The electromagnet includes a mounting portion formed therein for fixing the switch body to the installation location of the switch body, A safety switch comprising an electromagnet having a protruding portion that extends outward from the adsorption surface when the adsorption surface is viewed from the front, and the mounting portion being provided on the protruding portion.

2. The safety switch according to claim 1, wherein the protrusion is formed on the electromagnet such that when the adsorption surface and the surface to be adsorbed are adsorbed, the protrusion moves away from the magnetizing member in the direction normal to the adsorption surface.

3. A detection unit that detects whether a movable actuator having a magnetized member on which an adsorption surface is formed is within a predetermined range, A safety signal output unit that outputs a safety signal based on the detection result from the detection unit, An electromagnet on which an adsorption surface corresponding to the surface to be adsorbed is formed, A lock input unit that receives a lock instruction to lock the movement of the actuator, A drive control unit drives the electromagnet so that the adsorption surface of the electromagnet and the surface to be adsorbed of the actuator are attracted to each other based on the lock instruction received via the lock input unit, The electromagnet includes a mounting portion formed therein for fixing the switch body to the installation location of the switch body, A safety switch wherein the electromagnet has an outer circumferential surface formed around a central axis intersecting the center of the adsorption surface, and the end of the mounting portion is provided on the outer circumferential surface.

4. A detection unit that has a magnetized member on which an adsorption surface is formed and detects that a movable actuator is within a predetermined range, A safety signal output unit that outputs a safety signal based on the detection result from the detection unit, An electromagnet on which an adsorption surface corresponding to the surface to be adsorbed is formed, A lock input unit that receives a lock instruction to lock the movement of the actuator, A drive control unit drives the electromagnet so that the adsorption surface of the electromagnet and the surface to be adsorbed of the actuator are attracted to each other based on the lock instruction received via the lock input unit, The electromagnet has a mounting portion formed therein for fixing the switch body to the installation location of the switch body, A resin housing that houses the detection unit, the output unit, and the drive control unit, Equipped with, The electromagnet is connected to the resin housing, A safety switch in which the adsorption surface and mounting portion formed on the electromagnet are exposed.

5. The safety switch according to claim 4, comprising an output unit formed in the resin housing that outputs the safety signal.

6. A detection unit that detects whether a movable actuator having a magnetized member on which an adsorption surface is formed is within a predetermined range, A safety signal output unit that outputs a safety signal based on the detection result from the detection unit, An electromagnet on which an adsorption surface corresponding to the surface to be adsorbed is formed, A lock input unit that receives a lock instruction to lock the movement of the actuator, A drive control unit drives the electromagnet so that the adsorption surface of the electromagnet and the surface to be adsorbed of the actuator are attracted to each other based on the lock instruction received via the lock input unit, The electromagnet includes a mounting portion formed therein for fixing the switch body to the installation location of the switch body, The detection unit includes a first coil for exchanging wireless signals to detect that the actuator is within a predetermined range. The electromagnet includes a second coil that is driven by the drive control unit to generate a magnetic field for attracting the attracting surface of the electromagnet to the attracting surface of the actuator. The first coil and the second coil are wound in different directions from each other in this safety switch.

7. The system includes a resin housing that accommodates the detection unit, The safety switch according to claim 6, wherein the adsorption surface and the mounting portion formed on the electromagnet are exposed.

8. A detection unit that detects whether a movable actuator having a magnetized member on which an adsorption surface is formed is within a predetermined range, A safety signal output unit that outputs a safety signal based on the detection result from the detection unit, An electromagnet on which an adsorption surface corresponding to the surface to be adsorbed is formed, A lock input unit that receives a lock instruction to lock the movement of the actuator, A drive control unit drives the electromagnet so that the adsorption surface of the electromagnet and the surface to be adsorbed of the actuator are attracted to each other based on the lock instruction received via the lock input unit, The electromagnet includes a mounting portion formed therein for fixing the switch body to the installation location of the switch body, The detection unit includes a first coil for exchanging wireless signals to detect that the actuator is within a predetermined range. The electromagnet has a protruding portion that protrudes outward from the adsorption surface when the adsorption surface is viewed from the front, A safety switch in which, when the suction surface is viewed from the front, the suction surface is circular, the distance between the first coil and the center of the circle in the radial direction of the circle is less than or equal to the distance between the tip of the protrusion and the center of the circle in the radial direction of the circle, and the first coil is provided such that the position of the first coil in the circumferential direction of the circle coincides with the position of the protrusion in the circumferential direction of the circle.

9. The electromagnet includes a second coil that is driven by the drive control unit to generate a magnetic field for attracting the attracting surface of the electromagnet to the attracting surface of the actuator. The safety switch according to claim 8, wherein the first coil and the second coil have the same winding direction.

10. The safety switch according to any one of claims 1 to 9, wherein the electromagnet is attached to a metal member by the mounting portion.

11. The safety switch according to any one of claims 1 to 9, wherein the drive control unit drives the electromagnet so that the adsorption surface of the electromagnet and the adsorption surface of the actuator are attracted to each other, based on the detection result from the detection unit and the lock instruction received via the lock input unit.

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