Methods and apparatuses to identify devices

• US 6,988,667 B2
• Filed: 05/30/2002
• Issued: 01/24/2006
• Est. Priority Date: 05/31/2001
• Status: Expired due to Term

• Current Assignee: RUIZHANG TECHNOLOGY LIMITED COMPANY
• Original Assignee: Alien Technology Corporation
• Inventors: Stewart, Roger G., Smith, John Stephen
• Primary Examiner(s): St. Cyr, Daniel
• Application Number:
  US10/160,458
• Publication Number:
  US 20030019929A1
• Time in Patent Office: 1,335 Days
• Field of Search: 235/492, 235/385, 235/462.13, 235/462.46, 235/472.02, 235/487, 235/380
• US Class Current: 235/492
• 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 7/08 by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes
• CPC Class Codes: G06K 7/10049 binary tree

Abstract

A reader identifies tags without requiring or determining whether a response to an interrogation was a single response from a single tag or multiple responses from multiple tags. A method is performed by a tag in an identification system, and the method includes receiving a first data from a reader, and correlating the first data with a first corresponding portion of the tag'"'"'s identification code, and specifying a match if the first data matches the first corresponding portion, and receiving second data which, combined with the first data, is correlated with a second corresponding portion of th tag'"'"'s identification code.

Claims

1. A method performed by a tag, said method comprising:

receiving a first data from a reader;

correlating said first data with a first corresponding portion of an identification code of a tag;

transmitting a response of said reader if said first data matches said first corresponding portion; and

receiving a second data which is correlated with a second corresponding portion of said identification code.

2. A method as in claim 1 wherein said second data is received after said reader receives multiple responses from tags indicating a match to said first data and wherein said second data may include said first data.

3. A method as in claim 2 further comprising:

receiving a test code from said reader prior to receiving said first data; and

activating said tag only if said test code is correctly processed by said tag prior to receiving said first data.

4. A method as claim 1 wherein said first data comprises a first command and said second data comprises said first command or a second command.

5. A method as claim 4 wherein said first command and said second command specify one of a position of a bit pointer or a value of a bit pointed to by said bit pointer.

6. A method performed by a reader to identify a tag having an identification code, said method comprising:

transmitting a first data from said reader, for receipt by said tag, said first data corresponding to a first portion of said identification code;

receiving a response from said tag if said first data matches said first portion; and

transmitting a second data which corresponds to a second portion of said identification code.

7. A method as in claim 6 wherein said second data is transmitted after said reader receives multiple responses from tags indicating a match to said first data and wherein said second data may include said first data.

8. A method performed by a reader for identifying a tag, said method comprising:

transmitting a first data from said reader, said first data specifying a first search at a first level of a number space;

receiving a response from at least one tag;

transmitting a second data from said reader, said second data specifying a second search at a second level of said number space, wherein said second level corresponds to a second portion of said number space and said first level corresponds to first portion of said number space and said second portion is smaller than said first portion; and

storing a data structure which comprises said first portion and said second portion and which specifies tags which are identified and portions of said number space in which there are no tags.

9. A method as claim 8 wherein said number space is a binary number space and said data structure is a binary tree which is assembled as said reader receives responses from tags.

10. A method as claim 8 wherein said reader transmits said second data without regard to whether said receiving received a single response from one tag or a plurality of responses from a plurality of tags.

11. A method performed by a reader for identifying a tag having an identification code, said method comprising:

transmitting commands from a reader to any tags present, said commands causing a search of possible identification codes in a number space; and

transmitting a further command which requests tags in a portion of said number space to indicate whether said tags, if any, have a partial match to at least a part of an identification code, wherein if there are tags which are not yet identified in said portion, said reader transmits commands to search said portion before searching a larger portion of said number space.

12. A method as claim 11 wherein said search of said portion is a neighborhood search performed after identifying and muting a first tag which is also in said portion.

13. A method performed by a reader for identifying at least one tag having an identification code, said method comprising:

transmitting at least on command from a reader to any tags present, said command causing a search of possible identification codes;

transmitting a portion of an identification code; and

receiving, in response to said transmitting said portion of said identification code, a response, from tag, which indicates a match to said portion and which indicates at leas one next bit in said tag'"'"'s identification code.

14. A method as in claim 13 wherein said possible identification codes exist in a number space and wherein said reader determines a portion of said number space for further searching after receiving said at least one next bit in said response.

15. A method as claim 13 further comprising:

determining a relative strength of responses from tags indicating their corresponding at least one next bit.

16. A method as claim 15 wherein if said relative strength of a first next bit response exceeds a second next bit response, then said reader continues a search with said portion of said identification code and said first next bit response.

17. A method as in claim 16 wherein said first next bit response is a “

1” and

said second next bit response is “

0.”

18. A method performed by a tag having an identification code, said method comprising:

receiving a portion of identification code; and

transmitting from a tag, in response to said receiving said portion of said identification code, a response which indicates a match to said portion, if there is a match, and which indicates at least one next bit in said tag'"'"'s identification code.

19. A method as in claim 18 wherein if there is no match to said portion, said tag does not transmit a response.

20. A computer readable medium containing executable computer program instructions, which when executed by a data processing system, cause the data processing system to perform a method comprising:

receiving a first data from a reader;

correlating said first data with a first corresponding portion of an identification code of a tag;

transmitting a response said reader if said first data matches said first corresponding portion; and

receiving a second data which is correlated with a second corresponding portion of said identification code.

21. A computer readable medium as set forth in claim 20, wherein said second data is received after said reader receives multiple responses from tags indicating a match to said first data and wherein said second data may include said first data.

22. A computer readable medium as set forth in claim 21, wherein the method further comprises:

receiving a test code from said reader prior to receiving said first data; and

activating said tag only if said test code is correctly processed by said tag prior to receiving said first to data.

23. A computer readable medium as set forth in claim 20, wherein said first data comprises a first command and said second data comprises said first command or a second command.

24. A computer readable medium as set forth in claim 23, wherein said first command and said second command specify one of a position of a bit pointer or a value of a bit pointed to by said bit pointer.

25. A computer readable medium containing executable computer program instructions, which when executed by a data processing system, cause the data processing system to perform a method to identify a tag having an identification code, said method comprising:

transmitting a first data from said reader, for receipt by said tag, said first data corresponding to a first portion of said identification code;

receiving a response from said tag if said first data matches said first portion; and

transmitting a second data which corresponds to a second portion of said identification code.

26. A computer readable medium as set forth in claim 25, wherein said second data is transmitted after said reader receives multiple responses from tags indicating a match to said first data and wherein said second data may include said first data.

27. A computer readable medium containing executable computer program instructions, which when executed by a data processing system, cause the data processing system to perform a method for identifying a tag, said method comprising:

transmitting a first data from said reader, said first data specifying a first search at a first level of a number space;

receiving a response from at least one tag;

transmitting a second data from said reader, said second data specifying a second search at a second level of said number space, wherein said second level corresponds to a second portion of said number space and said first level corresponds to a first portion of said number space and said second portion is smaller than said first portion; and

storing a data structure which comprises said first portion and said second portion and which specifies to tags which are identified and portions of said number space in which there are no tags.

28. A computer readable medium as set forth in claim 27, wherein said number space is a binary number space and said data structure is a binary tree which is assembled as said reader receives responses from tags.

29. A computer readable medium as set forth in claim 27, wherein said reader transmits said second data without regard to whether said receiving received a single response from one tag or a plurality of responses from a plurality of tags.

30. A computer readable medium containing executable computer program instructions, which when executed by a data processing system, cause the data processing system to perform a method for a tag having an identifier code, said method comprising:

receiving, at said tag, data representing at least a portion of a test code from a reader;

processing said data in said tag and determining whether said test code has been properly received; and

silencing transmissions from said tag for at least one command properly received from said reader after said test code if said test code has not been properly received.

31. A computer readable medium containing executable computer program instructions, which when executed by a data processing system, cause the data processing system to perform a method for identifying a tag having an identification code, said method comprising:

transmitting commands from a reader to any tags present, said commands causing a search of possible identification codes in a number space; and

transmitting a further command which requests tags in a portion of said number space to indicate whether said tags, if any, have a partial match to at least a part of an identification code, wherein if there are tags which are not yet identified in said portion, said reader transmits commands to search said portion before searching a larger portion of said number space.

32. A computer readable medium as set forth in claim 31 wherein said search of said portion is a neighborhood search performed after identifying and muting a first tag which is also in said portion.

33. A computer readable medium containing executable computer program instructions, which when executed by a data processing system, cause the data processing system to perform a method for identifying at least one tag having an identification code, said method comprising:

transmitting at least one command from a reader to any tags present, said command causing a search of possible identification codes;

transmitting a portion of an identification code; and

receiving, in response to said transmitting said portion of said identification code, a response, from a tag, which indicates a match to said portion and which indicates at least one next bit in said tag'"'"'s identification code.

34. A computer readable medium as set forth in claim 33 wherein said possible identification codes exist in a number space and wherein said reader determines a portion of said number space for further searching after receiving said at least one next bit in said response.

35. A computer readable medium set forth in claim 33 further comprising:

determining a relative strength of responses from tags indicating their corresponding at least one next bit.

36. A computer readable medium as set forth in claim 35 wherein if said relative strength of a first next bit response exceeds a second next bit response, then said reader continues a search with said portion of said identification code and said first next bit response.

37. A computer readable medium as set forth in claim 36 wherein said first next bit response is a “

1” and

said second next bit response is “

0.”

38. A computer readable medium containing executable computer program instructions, which when executed by a data processing system, cause the data processing system to perform a method for a tag having an identification code, said method comprising:

receiving a portion of identification code; and

transmitting from a tag, in response to said receiving said portion of said identification code, a response which indicates a match to said portion, if there is a match, and which indicates at least one next bit in said tag'"'"'s identification code.

39. A computer readable medium as set forth in claim 38 wherein if there is no match to said portion, said tag does not transmit a response.

40. A tag comprising:

a receiver to receive a first data from a reader;

a processor coupled with said receiver, said processor is to correlate said first data with a first corresponding portion of an identification code of said tag; and

a transmitter coupled said processor, said transmitter is to transmit a response to said reader if said first data matches said first corresponding portion of said identification code, wherein said receiver is to receive a second data which is to be correlated with a second corresponding portion of said identification code.

41. A tag as in claim 40 further comprising:

an antenna, wherein said antenna is to receive a signal from said reader, said signal to include said first data from said reader;

a receive/transmit switch coupled to said antenna and said receiver, wherein said receive/transmit switch is to allow said first data to be received by said receiver and said receive/transmit switch coupled to said transmitter, wherein said receive/transmit switch is to allow said response to be transmitted from said antenna.

42. A tag as in claim 40 wherein said processor is a correlator.

43. A tag as in claim 40 wherein said second data is to be received after said reader receives multiple responses from tags indicating a match to said first data and wherein said second data may include said first data.

44. A tag as in claim 43 wherein said receiver is to receive a test code from said reader prior to said first data and said response is to be transmitted only if said test code is correctly processed by said tag prior to receiving said first data.

45. A tag as in claim 44 wherein said first data comprises a first command and said second data comprises said first command or a second command.

46. A tag as in claim 45 wherein said first command and said second command specify one of a position of a bit pointer or a value of a bit pointed to by said bit pointer.

47. A tag as in claim 45 further comprising inter-command memory to store at least one of said first command and a result of said first command.

48. A tag comprising:

a receiver to receive, at said tag, data representing at least a portion of a test code from a reader;

a processor coupled with said receiver, said processor is to process said data in said tag and is to determine whether said test code has been properly received; and

a transmitter coupled with said processor, said transmitter is to transmit a transmission from said tag, wherein said transmission from said tag is to be silenced for at least one command properly received from said reader after said test code if said test code has not been properly received.

49. A tag having identification code, said tag comprising:

a receiver to receive a portion of an identification code;

a processor coupled with said receiver; and

a transmitter coupled with said processor, said transmitter is to transmit a response from said processor which indicates a match to said portion, if there is a match, and which indicates at least one next bit in said tag'"'"'s identification code, said response is to be in response to receipt of said portion of said identification code.

50. A tag as in claim 49 wherein if there is no match to said portion, said tag does not transmit a response.

51. An apparatus to identify a tag having an identification code, said apparatus comprising:

a microprocessor to control a first data;

a transmitter coupled with said microprocessor, said transmitter is to transmit said first data, said first to data is to be received by said tag, said first data corresponding to a first portion of said identification code; and

a receiver coupled with said microprocessor, said receiver is to receive a response from said tag if said first data matches said first portion of said identification code, wherein said transmitter is to transmit a second data, which corresponds to a second portion of said identification code.

52. An apparatus in claim 51 wherein said second data is to be transmitted after multiple responses are received from tags indicating a match to said first data and wherein said second data may include said first data.

53. An apparatus to identify a tag, said apparatus comprising:

a microprocessor having a memory, said microprocessor is to control a search for tags;

a transmitter coupled with said microprocessor, said transmitter is to transmit said first data, said first to data specifying a first search at a first level of a number space; and

a receiver coupled with said microprocessor, said receiver is to receive a response from at least on tag, wherein said transmitter is to transmit a second data, said second data specifying a second search at a second level of said number space, wherein said second level corresponds to a second portion of said number space and said first level corresponds to a first portion of said number space and said second portion is smaller than said first portion and wherein a data structure is stored in said memory, said data structure comprises said first portion and said second portion and which specifies tags which are identified and portions of said number space in which there are no tags.

54. An apparatus as in claim 53 wherein said number space is a binary number space and said data structure is a binary tree, which is assembled as responses are received from tags.

55. An apparatus as in claim 53 wherein said apparatus is to transmit a second data without regard to ether said receiver received a single response from one tag or a plurality of responses from a plurality of tags.

56. An apparatus to identify a tag having an identification code, said apparatus comprising:

a microprocessor to send commands; and

a transmitter coupled with said microprocessor, said transmitter is to transmit said commands to any tags present, said commands causing a search of possible identification codes in a number space and said transmitter is to transmit a further command which requests tags in a portion of said number space to indicate whether said tags, if any, have a partial match to at least a part of an identification code, wherein if there are tags which are not yet identified in said portion, said apparatus is to transmit commands to search said portion before searching larger portion of said number space.

57. An apparatus as in claim 56 wherein said search of said portion is a neighborhood search performed after identifying and muting a first tag which is also in said portion.

58. An apparatus to identify at least one tag having an identification code, said apparatus comprising:

a microprocessor to send at least one command;

a transmitter coupled with said microprocessor, said transmitter is to transmit said at least one command from said apparatus to any tags present, said command causing a search of possible identification codes and said transmitter is to transmit a portion of an identification code; and

a receiver coupled with said microprocessor, said receiver is to receive in response to transmitting a portion of said identification code, a response, from a tag, which indicates match to said portion and which indicates at least one next bit in said tag'"'"'s identification code.

59. An apparatus in claim 58 wherein said possible identification codes exist in a number space and herein said microprocessor is to determine a portion of said number space for further searching after receiving said at least one next bit in said response.

60. An apparatus as in claim 58 wherein said microprocessor is to determine a relative strength of responses from tags indicating their corresponding at least one next bit.

61. An apparatus as in claim 60 wherein if said relative strength of a first next bit response exceeds a second next bit response, then said microprocessor continues a search with said portion of said identification code and said first next bit response.

62. An apparatus in claim 61 wherein said first next bit response is a “

1” and

said second next bit response is “

0.”

63. A tag comprising:

means for receiving a first data from a reader;

means for correlating said first data with a first corresponding portion of an identification code of a tag; and

means for transmitting response to said reader if said first data matches said first corresponding portion of said identification code, wherein said receiver is to receive a second data which is correlated with a second corresponding portion of said identification code.

64. A tag as in claim 63 further comprising:

antenna means, wherein said antenna means is to receive a signal from said reader, said signal to include said first data from said reader; and

switch means to allow said first data to be received by said means for receiving, and wherein said switch means to allow said response to be transmitted from said antenna means.

65. A tag as in claim 63 wherein said second data is received after said reader receives multiple responses from tags indicating a match to said first data and wherein said second data may include said first data.

66. A tag as in claim 65 wherein said means for receiving is to receive a test code from said reader prior to said first data and said response is to be transmitted only if said test code is correctly processed by said tag prior to receiving said first data.

67. A tag as in claim 66 wherein said first data comprises a first command and said second data comprises said first command or a second command.

68. A tag as in claim 67 wherein said first command and said second command specify one of a position of a bit pointer or a value of a bit pointed to by said bit pointer.

69. A tag as in claim 67, further comprising means for storing at least one of said first command and a result of said first command.

70. A tag comprising:

means for receiving, at said tag, data representing at least a portion of a lest code from a reader;

means for processing said data in said tag and to determine whether said test code has been properly received; and

means for transmitting transmission from said tag, wherein said transmission from said tag is to be silenced for at least one command properly received from said reader after said test code if said test code has not been properly received.

71. A tag having identification code, said tag comprising:

means for receiving, said means for receiving is to receive a portion of an identification code;

means for determining process said portion of said identification code; and

means for transmitting, said means for transmitting is to transmit a response from said means for determining which indicates a match to said portion, if there is a match, and which indicates at least one next bit in said tag'"'"'s identification code, said response is to be in response to receipt of said portion of said identification code.

72. An apparatus as in claim 71 wherein if there is no match to said portion, said means for transmitting does not transmit a response.

73. An apparatus to identify a tag having an identification code, said apparatus comprising:

means for controlling a first data;

means for transmitting said first data, said first data is to be received by said tag, said first data corresponding to a first portion of said identification code; and

means for receiving a response from said tag if said first data matches said first portion of said identification code, wherein said means for transmitting is to transmit a second data, which corresponds to a second portion of said identification code.

74. An apparatus as in claim 73 wherein said second data is to be transmitted after multiple responses are received from tags indicating a match to said first data and wherein said second data may include said first data.

75. An apparatus to identify a tag, said apparatus comprising:

means for controlling a first data;

means for storing data;

means for transmitting said first data, said first data specifying a first search at a first level of a number space; and

means for receiving a response from at least one tag, wherein said means for transmitting is to transmit a second data, said second data specifying a second search at a second level of said number space, wherein said second level corresponds to a second portion of said number space and said first level corresponds to a first portion of said number space and said second portion is smaller than said first portion and wherein a data structure is stored in said means for storing data, said data structure comprises said first portion and said second portion and which specifies tags which are identified and portions of said number space in which there are no tags.

76. An apparatus as in claim 75 wherein said number space is a binary number space and said data structure is a binary tree, which is assembled as responses are received from tags.

77. An apparatus as in claim 75 wherein said apparatus is to transmit a second data without regard to ether said means for receiving received a single response from one tag or a plurality of responses from a plurality of tags.

78. An apparatus to identify a tag having an identification code, said apparatus comprising:

means for sending commands; and

means for transmitting said commands to any tags present, said commands causing a search of possible identification codes in a number space and said means for transmitting is to transmit a further command which requests tags in a portion of said number space to indicate whether said tags, if any, have a partial match to at least a part of an identification code, wherein if there are tags which are not yet identified in said portion, said apparatus is to transmit commands to search said portion before searching a larger portion of said number space.

79. An apparatus in claim 78 wherein said search of said portion is a neighborhood search performed after identifying and muting a first tag which is also in said portion.

80. An apparatus to identify at least one tag having an identification code, said apparatus comprising:

means for transmitting, said means for transmitting is to transmit at least one command to any tags present, said command causing a search of possible identification codes and said means for transmitting is to transmit a portion of an identification code; and

means for receiving, said means for receiving is to receive in response to transmitting said portion of said identification code, a response, from a tag, which indicates a match to said portion and which indicates at least one next bit in said tag'"'"'s identification code.

81. An apparatus in claim 80, further comprising:

means for determining, herein said possible identification codes exist in a number space and where said means for determining is to determine a portion of said number space for further searching after receiving said at least one next bit in said response.

82. An apparatus in claim 81 wherein said means for determining is to determine a relative strength of responses from tags indicating their corresponding at least one next bit.

83. An apparatus as in claim 82 wherein if said relative strength of a first next bit response exceeds a second next bit response, then said means for determining continues a search with said portion of said identification code and said first next bit response.

84. An apparatus in claim 83 wherein said first next bit response is a “

1” and

said second next bit response is “

0.”