Safety switch for monitoring a closed position of two parts moveable relative to one another

• US 7,746,233 B2
• Filed: 07/06/2006
• Issued: 06/29/2010
• Est. Priority Date: 01/09/2004
• Status: Expired due to Fees

• Current Assignee: PILZ GmbH & Company KG
• Original Assignee: PILZ GmbH & Company KG
• Inventors: Barth, Steffen, Fleiner, Jurgen, Blaschke, Dietrich
• Primary Examiner(s): Wu; Daniel
• Assistant Examiner(s): Lu; Shirley
• Application Number:
  US11/481,991
• Publication Number:
  US 20070013236A1
• Time in Patent Office: 1,454 Days
• Field of Search: 340/545.1, 340/825.29, 340/572.8, 235/449
• US Class Current: 340/572.8
• CPC Class Codes: G01D 5/2066 by movement of a single coil with respect to a single other coil
• CPC Class Codes: H03K 17/9502 Measures for increasing reliability
• CPC Class Codes: H03K 17/9505 Constructional details
• CPC Class Codes: H03K 17/9525 controlled by an oscillatory signal H03K17/9537 takes precedence
• CPC Class Codes: H03K 2217/958 involving transponders

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

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.

2. The safety switch of claim 1, wherein the sensor antenna has a substantially omnidirectional characteristic.

3. The safety switch of claim 1, wherein the sensor antenna comprises a plurality of antenna elements having a plurality of directional characteristics aligned differently.

4. The safety switch of claim 1, wherein the sensor antenna comprises an air coil.

5. 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.

6. The safety switch of claim 5, wherein the coil is implemented in the form of a conductor track on the circuit board.

7. 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.

8. 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.

9. The safety switch of claim 8, wherein the field insulation is a magnetically conductive plate.

10. The safety switch of claim 8, wherein the field insulation is an electrically conductive plate.

11. 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.

12. 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.

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.

14. The safety switch of claim 13, wherein the sensor antenna has a substantially omnidirectional characteristic.

15. The safety switch of claim 13, wherein the sensor antenna comprises a plurality of antenna elements having a plurality of directional characteristics aligned differently.

16. The safety switch of claim 13, wherein the sensor antenna comprises an air coil.

17. 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.

18. The safety switch of claim 17, wherein the coil is implemented in the form of a conductor track on the circuit board.

19. 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.

20. 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.

21. 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.