# US 7,746,233 B2 · Safety switch for monitoring a closed position of two parts moveable relative to one another > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,746,233 B2 - Document ID: US7746233B2 - Status: Granted - Kind: B2 - Application number: 11/481,991 - Filed: 2006-07-06 - Published: 2007-01-18 - Granted: 2010-06-29 - Earliest claimed: 2004-01-09 - Assignees: Pilz GmbH & Co. KG - Inventors: Jürgen Fleiner; Steffen Barth; Dietrich Blaschke - Web page: https://patentgrep.com/patent/US7746233B2 ## CPC - G01D 5/2066: {by movement of a single coil with respect to a single other coil} - H03K 17/9502: {Measures for increasing reliability} - H03K 17/9525: {controlled by an oscillatory signal (H03K17/9537 takes precedence)} - H03K 17/9505: {Constructional details} - H03K 2217/958: involving transponders - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) ## Abstract A safety switch, which is particularly intended for monitoring a guard door on an automated installation, has an actuator and a sensor. The actuator comprises an actuator antenna and the sensor comprises a sensor antenna. The actuator and the sensor are coupled to one another like a transformer, in particular like a transponder, when the guard door is in the closed position. According to one aspect of the invention, the sensor antenna has a magnetic directional characteristic which allows transformer coupling with the actuator in at least two mutually perpendicular spatial directions as seen from the sensor antenna. ## Claims ### Claim 1 A safety switch for monitoring a closed position of a guard door in an automated installation, said guard door comprising a fixed part and a moveable part, and the safety switch comprising: an actuator and a sensor each adapted to be secured to one of the parts, wherein the actuator has a transponder including an actuator antenna and the sensor has a sensor antenna, wherein the antennas are configured to establish a transponder coupling, when the parts are in the closed position, wherein the sensor antenna has a magnetic directional characteristic which allows the transponder coupling in at least two spatial directions that are mutually perpendicular as seen from the sensor antenna, and further wherein the magnetic directional characteristic comprises a stronger first preferential direction and a weaker second preferential direction allowing the transponder coupling, wherein the sensor antenna is arranged in an antenna housing having housing walls, and wherein a distance between the sensor antenna and the housing walls in the first preferential direction is longer than in the second preferential direction. ### Claim 2 (depends on 1) The safety switch of claim 1, wherein the sensor antenna has a substantially omnidirectional characteristic. ### Claim 3 (depends on 1) The safety switch of claim 1, wherein the sensor antenna comprises a plurality of antenna elements having a plurality of directional characteristics aligned differently. ### Claim 4 (depends on 1) The safety switch of claim 1, wherein the sensor antenna comprises an air coil. ### Claim 5 (depends on 1) The safety switch of claim 1, wherein the sensor comprises a circuit board, and wherein the sensor antenna comprises a coil that is flatly arranged on the circuit board. ### Claim 6 (depends on 5) The safety switch of claim 5, wherein the coil is implemented in the form of a conductor track on the circuit board. ### Claim 7 (depends on 1) The safety switch of claim 1, wherein the sensor antenna, perpendicular to the first preferential direction, is arranged at same distances from at least two housing walls. ### Claim 8 (depends on 1) The safety switch of claim 1, wherein the sensor comprises a sensor housing having a mounting face and a field insulation which is arranged between the sensor antenna and the mounting face. ### Claim 9 (depends on 8) The safety switch of claim 8, wherein the field insulation is a magnetically conductive plate. ### Claim 10 (depends on 8) The safety switch of claim 8, wherein the field insulation is an electrically conductive plate. ### Claim 11 (depends on 1) The safety switch of claim 1, wherein the sensor comprises a sensor housing having a mounting face, and wherein a distance between the sensor antenna and the mounting face is approximately 5 mm or more. ### Claim 12 (depends on 1) The safety switch of claim 1, wherein the actuator antenna has a first orientation for establishing the transponder coupling in a first of the at least two perpendicular spatial directions, and the actuator antenna has a second orientation for establishing the transponder coupling in a second of the at least two perpendicular spatial directions, wherein the first and the second orientations are rotated by about 90° with respect to one another. ### Claim 13 A safety switch for monitoring an adjacent position of two parts which are moveable relative to one another, comprising: an actuator and a sensor each adapted to be secured to one of the parts, wherein the actuator has an actuator antenna and the sensor has a sensor antenna, wherein the antennas are configured to establish a defined transformer coupling, when the parts are in the adjacent position, wherein the sensor antenna has a magnetic directional characteristic which allows the defined transformer coupling in at least two spatial directions that are mutually perpendicular as seen from the sensor antenna, and further wherein the directional characteristic comprises a stronger first preferential direction and a weaker second preferential direction allowing the transformer coupling, wherein the sensor antenna is arranged in an antenna housing having housing walls, and wherein a distance between the sensor antenna and the housing walls in the first preferential direction is longer than in the second preferential direction. ### Claim 14 (depends on 13) The safety switch of claim 13, wherein the sensor antenna has a substantially omnidirectional characteristic. ### Claim 15 (depends on 13) The safety switch of claim 13, wherein the sensor antenna comprises a plurality of antenna elements having a plurality of directional characteristics aligned differently. ### Claim 16 (depends on 13) The safety switch of claim 13, wherein the sensor antenna comprises an air coil. ### Claim 17 (depends on 13) The safety switch of claim 13, wherein the sensor comprises a circuit board, and wherein the sensor antenna comprises a coil that is flatly arranged on the circuit board. ### Claim 18 (depends on 17) The safety switch of claim 17, wherein the coil is implemented in the form of a conductor track on the circuit board. ### Claim 19 (depends on 13) The safety switch of claim 13, wherein the sensor antenna, perpendicular to the first preferential direction, is arranged at same distances from at least two housing walls. ### Claim 20 (depends on 13) The safety switch of claim 13, wherein the actuator antenna has a first orientation for establishing the transformer coupling in a first of the at least two perpendicular spatial directions, and the actuator antenna has a second orientation for establishing the transformer coupling in a second of the at least two perpendicular spatial directions, wherein the first and the second orientations are rotated by about 90° with respect to one another. ### Claim 21 (depends on 13) The safety switch of claim 13, wherein the actuator comprises a transponder circuit connected to the actuator antenna, and wherein the transformer coupling is a transponder coupling.