Radio frequency identification device

• US 7,005,965 B2
• Filed: 02/14/2003
• Issued: 02/28/2006
• Est. Priority Date: 02/14/2003
• Status: Active Grant

• Current Assignee: Winbond Electronics Corporation
• Original Assignee: Winbond Electronics Corporation
• Inventors: Ho, Chin-Te, Chen, Mao-Song
• Primary Examiner(s): Holloway, III, Edwin C.
• Application Number:
  US10/366,660
• Publication Number:
  US 20040160310A1
• Time in Patent Office: 1,110 Days
• Field of Search: 340/10.2, 340/10.3, 340/10.32, 340/572.1, 370/314, 370/442, 235/383
• US Class Current: 340/10.2
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10039 interrogator driven, i.e. synchronous

Abstract

The present invention provides a radio frequency identification (RFID) device including a detector and several identification tags. The detector transmits time slot cycle signals, and each of the cycle signals is divided into several slots. The identification tags receive the time slot cycle signal, and each of the tags respectively contains a random generator to generate a random number. Individual identification tag responds to the detector in an assigned time slot corresponding to a random number generated by the random generator in each single time slot cycle.

Claims

1. A radio frequency identification (RFID) device, comprising:

a detector transmitting a time slot cycle signal, wherein each cycle of said time slot cycle signal is divided into a plurality of time slots;

a plurality of tags receiving said time slot cycle signal, each one of said plurality of tags responds to said detector in a random time slot; and

means in the detector for counting the responses from each one of said plurality of tags respectively with a plurality of cycles of said time slot cycle signal, wherein one of said plurality of tags is identified while the number of consecutive responses of said plurality of tags exceeds a predetermined threshold.

2. The RFID device according to claim 1, wherein each of said plurality of tags respectively contains a random generator to generate a random number, and responds to said detector in an assigned time slot corresponding to said random number in each said time slot cycle signal, wherein the range of any said random number cannot exceed the number of said plurality of time slots.

3. The RFID device according to claim 2, wherein said random generator is a resonance circuit.

4. The RFID device according to claim 2, wherein said random generator generates a new random number for each new cycle of said time slot cycle signal.

5. The RFID device according to claim 1, wherein said time slot cycle signal is a 13.56 MHz of electromagnetic wave.

6. The RFID device according to claim 1, wherein a mute signal is used as an interval between each of said time slots, and four continuous mute signals are used as an interval between each said cycle of said time slot cycle signal.

7. A method for a detector of a radio frequency identification (RFID) device being able to identify a plurality of tags with same identification codes comprising:

transmitting a continuous time slot cycle signal, wherein each cycle of said time slot cycle signal is divided into a plurality of time slots;

detecting all responses from said plurality of tags in the detection range; and

counting the responses from each of said plurality of tags respectively with a plurality of cycles of said time slot cycle signal, wherein one of said plurality of tags is identified while the number of consecutive responses of said plurality of tags exceeds a predetermined threshold.

8. The method according to claim 7, wherein each one of said plurality of tags further comprises a random generator generating a random number to decide the corresponding responsive time slot.

9. The method according to claim 7, wherein each one of said plurality of tags responds to said detector in a random time slot for each cycle of said time slot cycle signal.

10. The method according to claim 7, wherein said time slot cycle signal is a 13.56 MHz of electromagnetic wave.

11. The method according to claim 7, wherein a mute signal is used as an interval between each of said time slots, and four continuous mute signals are used as an interval between each cycle of said time slot cycle signal.