Switch acting in a contactless fashion

• US 20060220846A1
• Filed: 03/07/2006
• Published: 10/05/2006
• Est. Priority Date: 03/18/2005
• Status: Active Grant

• Current Assignee: K.A. Schmersal Holding KG
• Original Assignee: K.A. Schmersal Holding KG
• Inventors: Stratmann, Christoph
• Granted Patent: US 7,782,175 B2
• Time in Patent Office: Days
• US Class Current: 340/545.200
• CPC Class Codes: H03K 17/9525 controlled by an oscillatory signal H03K17/9537 takes precedence
• CPC Class Codes: H03K 2217/952 Detection of ferromagnetic and non-magnetic conductive targets
• CPC Class Codes: H03K 2217/958 involving transponders

Abstract

The invention relates to a switch acting in contactless fashion for the purpose of detecting the position of a first part with respect to a second part, having a transceiver for attachment to one of the parts, which transceiver is supplied with power by an electrical supply source and comprises a coil, which is connected to a transmission/reception circuit, for the purpose of transmitting an interrogation signal and for the purpose of receiving a response signal, which can be transmitted in response to the interrogation signal by a transponder which can be arranged on the other part, wherein in addition to a first path for processing the response signal to an evaluation circuit, a second path is provided which has a proximity circuit, which is connected on the input side to a connection of the coil and on the output side to the evaluation circuit for the amplitude of the voltage tapped off by the coil for the purpose of determining the distance between the parts.

Claims

1. Switch acting in contactless fashion for the purpose of detecting the position of a first part with respect to a second part, having a transceiver for attachment to one of the parts, which transceiver is supplied with power by an electrical supply source and comprises a coil, which is connected to a transmission/reception circuit, for the purpose of transmitting an interrogation signal and for the purpose of receiving a response signal, which can be transmitted in response to the interrogation signal by a transponder which can be arranged on the other part, wherein in addition to a first path for processing the response signal to an evaluation circuit, a second path is provided which has a proximity circuit, which is connected on the input side to a connection of the coil and on the output side to the evaluation circuit for the amplitude of the voltage tapped off by the coil for the purpose of determining the distance between the parts.

2. Switch according to claim 1, wherein the proximity circuit comprises a frequency filter, whose input is connected to the connection of the coil.

3. Switch according to claim 1, wherein the amplitude is the maximum amplitude of the AC voltage signal tapped off at the coil or the amplitude of the AC voltage signal tapped off at the coil and rectified.

4. Switch according to claim 1, wherein the evaluation circuit comprises a comparator for the purpose of comparing the amplitude with a threshold value.

5. Switch according to claim 1, wherein an enable signal can only be produced in the case of unique identification of the transponder when the amplitude exceeds a threshold value.

6. Switch according to claim 1, wherein the proximity circuit comprises an analogue-to-digital converter.

7. Switch according to claim 1, wherein the transponder is a rod transponder.

8. Switch according to claim 1, wherein the evaluation circuit is coupled to the transmission/reception circuit for the purpose of also evaluating the response signal.

9. Switch according to claim 8, wherein the transmission/reception circuit comprises an excitation circuit, which can be switched by the evaluation circuit, for the coil.

10. Switch according to claim 1, wherein the evaluation circuit comprises a microcontroller, and a frequency filter and/or a DC voltage circuit is implemented by programming of the microcontroller.