RFID transponder for a security system
View Patent ↗An RFID transponder for use in a security system based upon RFID techniques. The RFID transponder may be connected to an intrusion sensor. Example intrusion sensors are magnetically sensitive relay or LED detectors. The RFID transponder may also be connected to a passive infrared sensor. The RFID transponder can contain a battery, and the battery can be recharged by receiving and converting RF energy transmitted by the RFID reader. The security system also supports RFID transponders that may be carried by persons or animals, of that may contain a button used to signal an event such as an emergency. The RFID transponder typically uses backscatter modulation for responses, and can accept various modulation techniques for inbound wireless communications. The RFID transponder only responds when permitted.
1. An RFID transponder configured for use in a security system including at least a first RFID reader and at least a first controller controlling transmissions from the RFID reader, the RFID transponder is connected to an intrusion sensor and being enrolled with the controller and
receiving RF energy transmitted from the RFID reader,
interpreting the received RF energy to determine whether a response is permitted,
determining whether it has a response to send to the RFID reader, and
only sending a wireless communication to the RFID reader (a) in response to received RF energy, (b) if a response is permitted, and (c) if the RFID transponder has any response to send.
2. The RFID transponder of claim 1 , wherein the RFID transponder is connected to a passive infrared sensor.
3. The RFID transponder of claim 1 , wherein the said RFID transponder is a device wearable by a person or an animal.
4. The RFID transponder of claim 3 , wherein the said RFID transponder includes a button that can be pressed to change the state of a circuit in the said RFID transponder.
5. The RFID transponder of claim 1 , wherein the said RFID transponder is a master key RFID transponder associated with the said controller.
6. The RFID transponder of claim 1 , wherein the RFID transponder includes an energy store and uses the received RF energy to accumulate a charge in the energy store.
7. The RFID transponder of claim 6 , wherein the RFID transponder includes a charge pump to raise the voltage of the charge to be accumulated in the energy store.
8. The RFID transponder of claim 6 , wherein the energy store is a capacitor.
9. The RFID transponder of claim 6 , wherein the energy store is a battery.
10. The RFID transponder of claim 6 , wherein the RFID transponder includes a circuit monitoring the charged state of the energy store and reports the state of the energy store in a response wireless communication to the RFID reader.
11. The RFID transponder of claim 6 , wherein the RFID transponder includes a rectifier and a regulator producing proper voltage for use by the charge pump in charging the energy store.
12. The RFID transponder of claim 1 , wherein the intrusion sensor comprises a magnetically sensitive relay whose state changes based upon the presence or absence of a magnetic field.
13. The RFID transponder of claim 1 , wherein the intrusion sensor comprises an LED detector.
14. The RFID transponder of claim 13 , wherein the LED detector receives energy reflected from a surface.
15. The RFID transponder of claim 13 , wherein the LED detector receives energy emitted directly by an LED generator.
16. The RFID transponder of claim 15 , wherein the LED generator receives its power from another RFID transponder.
17. The RFID transponder of claim 1 , wherein the RFID transponder uses backscatter modulation to send wireless communications to the RFID reader.
18. The RFID transponder of claim 1 , wherein the RF energy is an unmodulated carrier wave.
19. The RFID transponder of claim 1 , wherein the RF energy is modulated so as to provide wireless communications.
20. The RFID transponder of claim 1 , wherein the response indicates whether an intrusion has been detected.
21. The RFID transponder of claim 1 , wherein the response is an interrupt.
22. The RFID transponder of claim 1 , wherein the RFID transponder includes means for attaching the transponder to the frame of an opening in a structure.
23. The RFID transponder of claim 1 , wherein the RFID transponder includes an energy management circuit.
24. The RFID transponder of claim 23 , wherein the energy management circuit comprises an overvoltage clamp for protection.
25. The RFID transponder of claim 1 , wherein the RFID transponder includes an encryption algorithm.
26. The RFID transponder of claim 1 , wherein the RFID transponder absorbs power radiated from the RFID reader.
27. The RFID transponder of claim 1 , wherein the RFID transponder communicates with the RFID reader using frequencies in one or both of two bands: the 902 to 928 MHz band and the 2.435 to 2.465 GHz band.
28. The RFID transponder of claim 1 , wherein the RFID transponder includes a microprocessor.
29. The RFID transponder of claim 1 , wherein the RFID transponder includes circuits for clock extraction and data modulation.
30. The RFID transponder of claim 1 , wherein the RFID transponder includes an antenna covered with a plastic housing accepting decoration, allowing the RFID transponder to be decorated after installation.
31. The RFID transponder of claim 1 , wherein the RFID transponder includes a button adapted to be activated by a user to solicit assistance.
32. An RFID transponder configured for use in a security system including at least a first RFID reader and at least a first controller controlling transmissions from the RFID reader, the RFID transponder is connected to an intrusion sensor and being enrolled with the controller, comprising means for fixing the transponder in a static location relative to the RFID reader, receiving RF energy transmitted from the RFID reader, interpreting the received RF energy to determine whether a response is permitted, determining whether it has a response to send to the RFID reader, and only sending a wireless communication to the RFID reader (a) in response to received RF energy, (b) if a response is permitted, and (c) if the RFID transponder has any response to send.