Abstract:
A device ( 1 ) monitors the state of a system ( 2 ), in particular safety switches for monitoring the closed state of safety equipment ( 2 ) of a machine ( 3 ). The device ( 1 ) is provided with a switch head ( 10 ) and an actuator ( 8 ), which can be brought into interaction with one another to control the device ( 1 ). The switch head ( 10 ) has an optical signaler ( 14 ) for optically signaling an operational state of the actuator ( 8 ) provided with a light-guide ( 28 ) having at least one entrance window ( 32 ) and at least one exit window ( 34, 36 ). In a state of the device ( 1 ) in which the switch bead ( 10 ) and the actuator ( 8 ) are interacting with one another, the light emitted by the signaler ( 14 ) enters, at least in part, via the at least one entrance window ( 32 ) and exits via the at least one exit window ( 34. 36 ).

Description:
FIELD OF THE INVENTION 
     The invention relates to a device for monitoring the state of a mechanism, in particular a safety switch for monitoring the engaged state of a safety device of a machine. 
     BACKGROUND OF THE INVENTION 
     Safety switches are used for monitoring the state of a safety device of a machine, for example, for monitoring the engaged state of a safety door of a safety enclosure for a machine tool or an industrial robot. When the safety device is in the engaged state, the safety switch can provide an enable signal for the operation of the machine. When the safety device is disengaged, the safety switch interrupts one or more electric circuits, for example, by an electrical contact pair that are actuated by positive locking or by an electronic switching element. The enable signal is then no longer provided. The associated machine can then be transferred to a safe operational state, for example it may be turned off, or the turning on of the machine may be prevented. 
     In some applications, the engaged state of the safety device is necessary to be detachably fixed, for example when, in an operational state of the machine, while the disengagement of the safety device is to be prevented. The fixation is only removed, and the safety device can only be disengaged, when the machine is at a complete standstill. 
     In the case of safety switches having mechanical actuators, such a fixation or guard control is achieved by locking the mechanical actuator in a state in which it is inserted into the switch head, for example. Alternatively, a guard control using magnetic force is possible in the case of mechanical actuators, but in particular in the case of electronic actuators. A corresponding guard control system of a safety switch is known from DE 101 46 828 A1. 
     As a rule, the safety switches are connected to higher-level control systems, to which output signals are transmitted and can also be indicated there on a display. If an operator wishes to know the current state of the safety switch and the guard control for example, the operator does so using the control system. 
     EP 0 990 835 A 1 discloses a mechanical, electromechanical or otherwise driven device, having of at least two parts that can be moved toward one another and waveguides inside the parts. These waveguides are disposed such that in a specific position, the light waves pass through all partial waveguides and are detected. In the remaining positions, the passage of the light waves is inevitably interrupted. 
     DE 196 49 593 discloses a locking mechanism for controlling access to working equipment, wherein the locking mechanism has an optical sensor having a transmitter and a receiver. Only when the locking mechanism is in the engaged state, in which the operation of the working equipment is enabled, does the receiver receive coded optical signals that are emitted by the transmitter. The output signal of the transmitter is read into an evaluation device. The operation of the working equipment is blocked or enabled by the evaluation device. 
     FR 2 684 167 A discloses a device having two connectible profiles made of aluminum. Fiber optic elements are disposed in the two profile pieces such that, when the profiles are connected together, an optical contact bridge is formed. 
     DE 692 01 486 T2 discloses an electromagnetic closing device having an electromagnet disposed in an elongated, channel-shaped housing. The housing and the electromagnet have elongated projections and/or recesses, which interact with one another such that, with the exception of the longitudinal movement, any movement of the electromagnet is prevented. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an improved generic device, the operating states of which can be safely determined with the least possible effort and on an ongoing basis. 
     The object is basically achieved by the device that can have a switch head and an actuator, which may be brought into interaction with one another to control the device. For example, the switch head may be disposed on a fixed part of the mechanism, for example on a frame of a protective screen, and the actuator may be disposed on a safety door movable with respect to the frame. When the door is closed, the switch head and the actuator are in interaction with one another, so that the device indicates the engaged state of the safety device to a higher-level control device. 
     According to the present invention, a part of the device, in particular the switch head, has an optical signaler for optically indicating an operational state of the device. For example, operational readiness and/or the engaged state of the safety device may be indicated. The other part of the device, in particular the actuator, has a light-conductor with at least one entrance window and at least one exit window for the light emitted by the optical signaler. In one state of the device, in which the switch head and the actuator are in interaction with one another, in particular in the engaged state of the safety device, the light emitted by the signaler enters into the light-guide by at least one of the entrance windows, and is guided by this light-guide to at least one of the exit windows, where the light exists. The signal from the optical signaler can then also be perceived in the engaged state of the safety device. 
     The optical signaler is preferably disposed on the switch head, which already has an electrical energy supply due to the other functions thereof. By contrast, the light-guide may preferably be disposed on the actuator, which, for example, is disposed on a movable part and need not have an electrical energy supply. 
     Advantageously, optical signaling by the device according to the invention is also possible, when the optical signaler is covered by the actuator in the state of the switch head and the actuator being in interaction with one another, in particular in contact with one another. In addition, the optional plurality of exit windows makes allows emitting the optical signal in different directions, for example simultaneously, both inside and outside of the safety device. At the same time, the optical signaler is disposed such that it is protected against contamination, damage and/or manipulation. In one embodiment, the entrance window and/or the exit window are flush with the surface surrounding them. Both contamination of and damage to the light-guide are thereby reliably prevented. 
     In one embodiment, the optical signaler is disposed on the switch head and at least one entrance window is disposed on the actuator such that, in the state of the device in which the switch head and the actuator are in interaction with one another, the optical signaler and the entrance window are disposed opposite one another. An advantageous coupling of the light emitted by the signaler is thereby ensured. At the same time, the optical signaler is covered by the actuator and is thereby protected against contamination and damage. 
     In one embodiment, the beam direction of the light exiting the exit window runs at an angle, in particular transversely as compared to the beam direction of the light generated by the light source of the optical signaler. The optical signal can thereby be emitted in different directions, in particular also in those directions, which cannot be covered by the optical signaler in the engaged state of the safety device for example. The beam direction is preferably deflected by the light-guide, for example by appropriate reflecting surfaces or partially permeable sections. 
     In one embodiment, the optical signaler has a light source and an additional light-guide. A light exit window may follow the additional light-guide or the additional light-guide itself may form the light exit window. A light emitting diode may be used as a source for the optical signaler, preferably a light emitting diode. The diode emits light signals of different colors depending on the control. Like the light-guide in the actuator, the additional light-guide may be made out of a plastic that is transparent to visible light, for example out of polymethylmethacrylate. 
     In one embodiment, the light-guide has a beam splitter, in particular in the form of a prism, which splits the light that enters by the entrance window to at least two exit windows. The optical signaler likewise then can have a beam splitter to allow the light emitted by the light source to exit to more than one light exit window. In particular when an efficient light source is used, the distribution of the emitted light beam into a plurality of partial beams is not detrimental to the visibility of the optical signal. If necessary, critical operating states may be signaled by a special light color and/or by increased light intensity and/or a pulsed light signal. 
     In one embodiment, the switch head is disposed, at least in part, in a groove of a profile, for example of an aluminum profile, as is used in industrialized building. The profile may be part of the device, but at the same time may also be part of the safety device by a corresponding mounting. In the state in which the switch head and the actuator are in interaction with one another, an light exit window of the optical signaler is covered by the actuator, which is likewise disposed, at least in part, in a groove of a profile. The arrangement in the groove of a profile ensures an especially space-saving construction. Moreover, not only the optical signaler, but also the switch head and, if applicable, the actuator, are disposed such that they are effectively protected against contamination and, in particular, against damage. 
     In one embodiment, the device has a guard locking device for detachably fixing a predefinable state of the mechanism, in particular the engaged state of the safety device. In any case, a state of the guard locking device can also be signaled by the optical signaler, for example the state “Guard control ready”, “Guard control activated”, “Amount of clamping force sufficient”. The amount of clamping force can also be optically signaled, for example, by a special light color and/or with increased light intensity and/or a pulsed light signal. 
     In one embodiment, the guard locking device has a magnet, preferably disposed in the switch head, which, in the state of the device in which the switch head and the actuator are in interaction with one another, can be brought into an operative connection with a counter element or cross element of the actuator that conducts the magnetic flux. 
     The magnet may, in particular, comprise an electromagnet, which attracts the counter element of the actuator, and when energized, fixes the counter element in the attracted state. This state may be indicated by the optical signaler and emitted in different directions by the light-guide. 
     In one embodiment, the switch head has a read head, which, in the state of the device in which the switch head and the actuator are in interaction with one another, is in an electrically contactless interaction with the actuator. To this end, the actuator may have a transponder, which is encoded with a unique identifier. The state of a successful decoding, and therefore acceptance of the actuator by the safety switch, may also be indicated by the optical signaler. 
     The features mentioned in the description may be essential to the invention either individually, or in any combination. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the drawings that form a part of this disclosure: 
         FIG. 1  is a schematic top view of an overall assembly of a device according to a first exemplary embodiment of the invention; 
         FIG. 2  is a perspective view of a switch head disposed in a profile of the device of  FIG. 1 ; 
         FIG. 3  is an enlarged side view in section of the optical signaler of  FIG. 2 ; 
         FIG. 4  is an enlarged side view in section of the read head of  FIG. 2 ; 
         FIG. 5  is a perspective view of an actuator of the device of  FIG. 1 ; 
         FIG. 6  is an enlarged side view in section of the actuator of  FIG. 5 ; 
         FIG. 7  is a side view of an actuator according to a second exemplary embodiment of the invention; and 
         FIG. 8  is an end view through the actuator of  FIG. 7  transverse to the longitudinal axis of the switch head. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a top view schematically illustrating the overall assembly of a device  1  for monitoring the state of a safety device  2  for a machine  3 , in particular of the engaged state of a safety door, with which a space separator can be locked, for example to protect the operator from being endangered by the machine  3  that is operating. 
     The safety device  2  has a first part  4 , for example a frame. The first part  4  has an opening  5 , which can be closed by a second part  6 , for example by a safety door. The safety door can be moved relative to the first part  4  according to the double arrow  9  and may be movably mounted by mounting elements  11 . Alternatively to being slid open and closed, the safety door may also be pivoted. 
     The device  1  preferably has a switch element  7  disposed on the fixed first part  4  of the safety device  2 . The switch element comprises a switch head  10 , as well as an actuator  8  preferably disposed on the movable second part  6 . The actuator  8  can be brought into operative connection with the switch head  10  when the safety door is closed to control the switch element  7 . The switch element  7  may either turn the machine  3  on or off itself, or may do so by separate switch elements or by a secondary or higher-level control device. 
     In the embodiment, the actuator  8  has a transponder  66  ( FIG. 7 ) not shown in  FIG. 1 , which can interact with the switch head  10  in an electrically contactless manner. The switch head has a reader coil  30  ( FIG. 4 ). An interaction is thereby only possible, when the safety device  2  is engaged. In a first operating mode, for example, a switch element is engaged by the interaction between the actuator  8  and the switch head  10  when the safety device  2  is engaged. An enable signal is thereby provided for the operation of the machine  3 . When the safety device  2  is disengaged, the interaction is interrupted, the switch element is disengaged, and the machine  3  is shut off. 
     The device  1  may also have a guard control, by which the engaged state of the safety device  2  can be releasably locked. The guard control may be implemented mechanically, for example preferably by a positive locking fixing of the actuator  8  to the switch head  7 , or by a magnetic force. 
     The switch head  10  has an optical signaler  14 , which has a light source  46  and a light-conductor  48 . Light-conductor  48  guides the light from the light source  46  to the surface of the switch head  10 . In the engaged state of the safety device  2 , the light  26  emitted by the signaler  14  can enter into the actuator  8  via the entrance window  32 , and after being deflected 90° by a light-guide  28 , can exit at the two exit windows  34 ,  36 . Thus, the signal from the signaler  14  can thereby be perceived even in the engaged state of the safety device  2 , both inside and outside of the safety device  2 , regardless of the fact that the signaler  14  is covered by the actuator  8 . 
       FIG. 2  shows a perspective view of an embodiment of a switch head  10  disposed in a profile  12 .  FIGS. 3 and 4  show an enlarged illustration of details of the switch head  10 . The optical signaler  14  is disposed in a groove  16  of the profile  12 . Also disposed in the groove  16  is an electromagnet of a locking device having a pole shoe  18  for releasably fixing a predefinable state of the safety device  2 . In addition, the read head  20  is disposed in the groove  16 . The optical signaler  14 , the electromagnet and the read head  20  are preferably implemented in a single assembly and are electrically connected by a shared connection line  24  that extends along the groove  16 . In particular, individual components may each be cast individually connected to one another by the casting compound  30  or may even be cast in the profile  12 . 
     The signaler  14  comprises the light source  46 , which is disposed on a printed circuit board  44 . The light source may also be a multi-colored LED if necessary. The light emitted by the light source  46  is guided by the light-guide  48  to a light exit window  22 , which exit window is flush with the surrounding surface of the switch head  10 . 
     The read head  20  has a solenoid  40  disposed on a printed circuit board  38 , which circuit board is covered by a cover  42 . The cover  42  is flush with the profile  12 . The solenoid  40  may exchange signals with a counterpart disposed on the actuator  8  in an electrically contactless manner, for example by a transponder  66 . 
       FIG. 5  shows a perspective view of an actuator  8 , which can be brought into interaction with the switch head  10  in  FIG. 2  and which thereby controls the device  1 . The actuator  8  is likewise disposed, at least in sections, in a groove  62  of an additional profile  52 . The actuator  8  has a cross element  54 . By cross element  54 , the magnetic flux emitted by one pole shoe  18  enters an adjacent pole shoe  18  and can be conducted. The cross element  54  is attracted when the electromagnet of the switch head  10  is energized and held in contact with the pole shoes  18 . The safety device  2  is then locked shut. The cross element  54  is fixed to the additional profile  52  by a fastening element  60 . The position along the groove  62  can be fixed by the fixing element  64 . 
       FIG. 6  shows an enlarged illustration of a cross section through the actuator  8  in the region of the light-guide  28 . The contour of the light-guide  28  is adapted to the contour of the surrounding fastening element  60  in the region of the light  26  emitted by the signaler  14 . In the embodiment, this contour is curved with the exception of a central planar section, the extension of which is adapted to the size of the light exit window  22 . The incident light is split by reflection at a beam splitter  56  into two partial beams that extend perpendicular to the incident light. The partial beams each exit the light-guide  28  at an exit window  34 ,  36 . The contour of the light-guide  28  is adapted to the surrounding fastening element  60  in the region of the exit windows  34 ,  36  and is curved in the embodiment. 
       FIG. 7  is a side view of a second embodiment of an actuator  108  in the engaged state of the safety device  2 , thus in contact with the switch head  10  from  FIG. 2  disposed in the profile  12 . The assembly in  FIG. 7 , including the switch head  10  and the actuator  108 , form a safety switch. By the safety switch, the locked state of the safety device  2  may not only be fixed, but this state can also be signaled to a higher-level machine control. 
     The actuator  108  is, in particular, provided to attach a preferably plate-shaped second part  6  of the safety device  2  to the front side, for example, to the front side of a glass door. The second part  6  can be moved by a handle  78  disposed on a handle plate  76 . The second part  6  may be a swinging door, a lift gate or a revolving door, for example. 
       FIG. 8  is a sectional view through the actuator  108  in  FIG. 7 , transverse to the longitudinal axis of the switch head  10 , in the region of the light-guide  128 . Corresponding to the light exit window  22 , the contour of the light-guide  128  in the region of the light  26  emitted by the signaler  14  is initially centrally planar and then curved. The incident light is split by reflection at a beam splitter into two partial beams that extend perpendicular to the incident light, which partial beams each exit the light-guide  128  at an exit window  134 ,  136 . The contour of the light-guide  128  is adapted to the surrounding fastening element  160  in the region of the exit windows  134 ,  136  and is essentially planar in the embodiment. 
     The actuator  108 , in particular the associated fastening element  160 , has an essentially U-shaped cross section with two brackets  72 ,  74 , between which the second part  6  of the safety device is accommodated. The two brackets  72 ,  74  have a plurality of elongated holes  70 , preferably disposed equidistantly on the brackets  72 ,  74 , which holes are paired with one another. Essentially cylindrical fasteners  80  are inserted into the elongated holes  70 , by which fasteners the actuator  108  may be firmly but movably attached to the second part  6 . 
     The actuator  108  can be pivoted, relative to the second part  6 , about a first axis  82 , which extends at a right angle to the longitudinal axis of the actuator  108 . In the embodiment, that axis extends perpendicular to the drawing plane of  FIG. 7 , and/or can be pivoted about a second axis  84 , which second axis  84  extends parallel to the longitudinal axis of the actuator  108 . In the embodiment, the second axis  84  extends perpendicular to the drawing plane of  FIG. 8 . To this end, both brackets  72 ,  74  have surfaces on their inner sides, the spacing between which surfaces increases in the direction of the free end of the brackets  72 ,  74 . The inner surfaces of the brackets  72 ,  74  thereby also form a stop for the pivoting movement around the second axis  84 . In addition, the actuator  108  can be displaced along a direction  88  that extends perpendicular to the longitudinal axis of the actuator  108 . The actuator  108  can thereby be deflected when the second part  6  is closed after contact with the switch head  10  and in particular, may be held, spring-loaded, in contact with the switch head  10 , in particular on the pole shoes  18 . To this end, the actuator  108  may have a spring element, which, in particular, may be disposed between the fastening element  160  and the front end of the second part  6 , and may be formed by the fastening element  160  as a single piece. 
     While various embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the claims.