ANTI-COLLISION COUPLING FOR CONTACTLESS CARDS

• US 20110062233A1
• Filed: 11/23/2010
• Published: 03/17/2011
• Est. Priority Date: 01/03/2005
• Status: Active Grant

• Current Assignee: Yong-Wook Kim
• Original Assignee: Yong-Wook Kim
• Inventors: KIM, Yong-Wook
• Granted Patent: US 9,189,665 B2
• Time in Patent Office: Days
• US Class Current: 235/435
• 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 7/10019 resolving collision on the communication channels between simultaneously or concurrently interrogated record carriers. collision between the communication channels used by wireless communication devices, where the solution is not particularly adapted for RFIDs or the like, H04W74/08
• CPC Class Codes: G06K 7/10029 the collision being resolved in the time domain, e.g. using binary tree search or RFID responses allocated to a random time slot
• CPC Class Codes: G06K 7/10069 the collision being resolved in the frequency domain, e.g. by hopping from one frequency to the other frequency hopping or spread spectrum techniques H04B7/00
• CPC Class Codes: G06K 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions

Abstract

Contactless cards and a corresponding anti-collision coupling method are provided, where the method includes requesting that the cards transmit their unique identifiers that each include a fixed number of bytes, receiving the unique identifiers simultaneously as byte-wise positive pulses, counting the received positive pulses, and determining that more than one card responded if the number of received positive pulses exceeds the fixed number of bytes; and where the contactless cards each include a unique identifier having a number of bytes, a receiver for receiving an anti-collision command indicative of a desired identifier byte, a comparator in signal communication with the receiver for comparing the desired identifier byte with a corresponding byte of the unique identifier, and a transmitter responsive to the comparator for transmitting the unique identifier as byte-wise positive pulses if the desired identifier byte matches the corresponding byte of the unique identifier.

Claims

1. A method of detecting at least one contactless device that has a unique identification code (UID), the method comprising:

requesting transfer of a UID;

receiving at least one positive pulse indicative of a UID; and

detecting whether more than one UID was transferred if the number of positive pulses received exceeds the number expected for one UID.

2. A method as defined in claim 1 wherein the UID comprises at least one byte, each byte being received in the shape of a positive pulse.

3. A method as defined in claim 1 wherein one UID was transferred, the method further comprising activating the device corresponding to the transferred UID.

4. A method as defined in claim 2 wherein more than one UID was detected, the method further comprising:

selecting a first UID byte from the received UID bytes;

requesting transfer of a UID having the selected first UID byte;

receiving at least one positive pulse indicative of a UID; and

detecting whether more than one UID having the selected first UID byte was transferred if the number of positive pulses received exceeds the number expected for one UID.

5. A method as defined in claim 4 wherein one UID having the selected first UID byte was transferred, the method further comprising activating the card corresponding to the transferred UID.

6. A method as defined in claim 4 wherein more than one UID having the selected first UID byte was detected, the method further comprising:

selecting a second UID byte from the received UID bytes;

requesting transfer of a UID having the selected first UID byte and the selected second UID byte;

receiving at least one positive pulse indicative of a UID; and

detecting whether more than one UID having the selected first UID byte and the selected second UID byte was transferred if the number of positive pulses received exceeds the number expected for one UID.

7. A method as defined in claim 6 wherein one UID having the selected first UID byte and the selected second UID byte was transferred, the method further comprising activating the card corresponding to the transferred UID.

8. A method as defined in claim 6 wherein more than one UID having the selected first UID byte and the selected second UID byte was detected, the method further comprising:

selecting another UID byte from the received UID bytes;

requesting transfer of a UID having the selected first UID byte and the selected second UID byte and the selected other UID byte;

receiving at least one positive pulse indicative of a UID; and

detecting whether more than one UID having the selected first UID byte and the selected second UID byte and the selected other UID byte was transferred if the number of positive pulses received exceeds the number expected for one UID.

9. A method as defined in claim 8 wherein one UID having the selected first UID byte and the selected second UID byte and the selected other UID byte was transferred, the method further comprising activating the card corresponding to the transferred UID.

10. A method of identifying a contactless device having a unique identification code (UID) to a reader, the method comprising:

receiving a UID call command from a reader; and

transferring at least one positive pulse indicative of the UID to the reader.

11. A method as defined in claim 10, further comprising:

receiving an anti-collision command and at least one UID value from a reader; and

if the at least one UID value from the reader matches a corresponding portion of the UID of the device, transferring at least one positive pulse indicative of the UID to the reader.

12. A reader for detecting at least one contactless device that has a unique identification code (UID), the reader comprising:

a UID call commander for requesting transfer of a UID;

a receiver in signal communication with the UID call commander for receiving at least one positive pulse indicative of a UID; and

a detector in signal communication with the receiver for detecting whether more than one UID was transferred if the number of positive pulses received exceeds the number expected for one UID.

13. A reader as defined in claim 12 wherein the UID comprises at least one byte, the receiver disposed for receiving each byte in the shape of a positive pulse.

14. A reader as defined in claim 12, further comprising an activation unit in signal communication with the detector for activating a contactless device corresponding to a transferred UID.

15. A reader as defined in claim 13 disposed for detecting more than one UID, further comprising:

a byte selector in signal communication with the detector for selecting a UID byte from the received UID bytes; and

an anti-collision commander in signal communication with the byte selector for requesting transfer of a UID having the selected UID byte,

wherein the receiver is disposed for receiving at least one positive pulse indicative of a UID responsive to the anti-collision commander and the detector is disposed for detecting whether more than one UID having the selected UID byte was transferred if the number of positive pulses received exceeds the number expected for one UID.

16. A program storage device readable by a machine to execute program steps for detecting at least one contactless device that has a unique identification code (UID), the program steps comprising:

requesting transfer of a UID;

receiving at least one positive pulse indicative of a UID; and

detecting whether more than one UID was transferred if the number of positive pulses received exceeds the number expected for one UID.

17. A program storage device as defined in claim 16 wherein the UID comprises at least one byte, each byte being received in the shape of a positive pulse, and more than one UID was detected, the program steps further comprising:

selecting a UID byte from the received UID bytes;

requesting transfer of a UID having the selected UID byte;

receiving at least one positive pulse indicative of a UID; and

detecting whether more than one UID having the selected UID byte was transferred if the number of positive pulses received exceeds the number expected for one UID.

18. A program storage device readable by a machine to execute program steps for identifying a contactless device having a unique identification code (UID) to a reader, the program steps comprising:

receiving a UID call command from a reader;

transferring at least one positive pulse indicative of the UID to the reader;

receiving an anti-collision command and at least one UID value from a reader; and

if the at least one UID value from the reader matches a corresponding portion of the UID of the card, transferring at least one positive pulse indicative of the UID to the reader.

19. A contactless card reader, comprising:

a transmitter for transmitting an anti-collision command indicative of at least one desired identifier byte;

a receiver for receiving the unique identifier as byte-wise positive pulses if the at least one desired identifier byte matches the at least one corresponding byte of the unique identifier; and

a detector in signal communication with the receiver for detecting a collision when the number of positive pulses exceeds the number of bytes in the unique identifier.

20. A contactless card reader as defined in claim 19, further comprising:

a caller in signal communication with the transmitter for calling all contactless cards within a given range of the reader;

a memory in signal communication with the receiver for storing in an ordered byte-wise manner all unique identifier bytes received in response to the caller; and

an anti-collision commander in signal communication with the memory and the transmitter for issuing an anti-collision command to differentiate between multiple contactless cards.

21. A contactless card reader as defined in claim 20 wherein the caller calls all contactless cards within a given range of the reader at a periodic interval.

22. A contactless card reader as defined in claim 20 wherein the caller calls all contactless cards within a given range of the reader in response to a passive indication of at least one card.

23. A contactless card reader as defined in claim 20 wherein the memory is configured as a top matrix having a separate column and row for each byte of a unique identifier and having an additional row for each non-duplicate byte entry in any column.

24. A contactless card reader as defined in claim 23 wherein the detector fills in all remaining rightmost byte values for a row with the byte values of a unique identifier for a given card whenever a collision is not detected.

25. A contactless card reader as defined in claim 23 wherein the detector fills in one leftmost of the remaining byte values for a row with a commanded byte value of a unique identifier for a given card whenever a collision matches the existing byte and position.

26. An anti-collision coupling method for contactless cards, the method comprising:

requesting that the cards transmit their unique identifiers, which each comprises a fixed plurality of bytes;

receiving the unique identifiers simultaneously as byte-wise positive pulses;

counting the received positive pulses; and

determining that more than one card responded if the number of received positive pulses exceeds the fixed plurality of bytes.

27. An anti-collision coupling method as defined in claim 26, further comprising:

initializing a byte position counter;

setting a byte value to a byte value received in the first byte position of the unique identifiers; and

forming an anti-collision command having the byte position counter and the byte value.

28. An anti-collision coupling method as defined in claim 27, further comprising:

transmitting the anti-collision command comprising the byte position counter and at least one byte value to the cards;

receiving the unique identifiers simultaneously as byte-wise positive pulses;

counting the received positive pulses; and

determining if more than one card responded if the number of received positive pulses exceeds the fixed plurality of bytes.

29. An anti-collision coupling method as defined in claim 28, further comprising, if more than one card responded:

incrementing the byte position counter;

setting the byte value to a byte value received in the incremented byte position of the unique identifiers;

updating the anti-collision command by updating the byte position counter and adding the byte value; and

repeating the steps of claim 33.

30. An anti-collision coupling method as defined in claim 28, further comprising, if only one card responded:

determining that the reader has not called all of the unique identifier bytes corresponding to the current byte position counter;

setting the byte value to another byte value received in the first byte position of the unique identifiers;

updating the anti-collision command with the current byte value; and

repeating the steps of claim 28.

31. An anti-collision coupling method as defined in claim 28, further comprising, if only one card responded:

determining that the reader has called all of the unique identifier bytes corresponding to the current byte position counter; and

activating the called cards corresponding to the received unique identifiers.

32. A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform program steps for anti-collision coupling of contactless cards, the program steps comprising:

requesting that the cards transmit their unique identifiers, which each comprises a fixed plurality of bytes;

receiving the unique identifiers simultaneously as byte-wise positive pulses;

counting the received positive pulses; and

determining that more than one card responded if the number of received positive pulses exceeds the fixed plurality of bytes.

33. A program storage device as defined in claim 32, the program steps further comprising:

initializing a byte position counter;

setting a byte value to a byte value received in the first byte position of the unique identifiers; and

forming an anti-collision command having the byte position counter and the byte value.

34. A program storage device as defined in claim 33, the program steps further comprising:

transmitting the anti-collision command comprising the byte position counter and at least one byte value to the cards;

receiving the unique identifiers simultaneously as byte-wise positive pulses;

counting the received positive pulses; and

determining if more than one card responded if the number of received positive pulses exceeds the fixed plurality of bytes.

35. A program storage device as defined in claim 34, the program steps further comprising, if more than one card responded:

incrementing the byte position counter;

setting the byte value to a byte value received in the incremented byte position of the unique identifiers;

updating the anti-collision command by updating the byte position counter and adding the byte value; and

repeating the program steps of claim 39.

36. A program storage device as defined in claim 34, the program steps further comprising, if only one card responded:

determining that the reader has not called all of the unique identifier bytes corresponding to the current byte position counter;

setting the byte value to another byte value received in the first byte position of the unique identifiers;

updating the anti-collision command with the current byte value; and

repeating the program steps of claim 34.

37. A program storage device as defined in claim 34, the program steps further comprising, if only one card responded:

determining that the reader has called all of the unique identifier bytes corresponding to the current byte position counter; and

activating the called cards corresponding to the received unique identifiers.