Electronic label reading system

• US 20030067414A1
• Filed: 09/26/2002
• Published: 04/10/2003
• Est. Priority Date: 12/03/1999
• Status: Active Grant

• Current Assignee: Tagsys Australia Pty Limited
• Original Assignee: Tagsys Australia Pty Limited
• Inventors: Kalinowski, Richard, Cole, Peter H, Hall, David Malcolm, Turner, Leigh Holbrook
• Granted Patent: US 6,992,567 B2
• Time in Patent Office: Days
• US Class Current: 343/742
• 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 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles
• CPC Class Codes: G06K 7/10425 the interrogation device being arranged for interrogation of record carriers passing by the interrogation device
• CPC Class Codes: G06K 7/10435 the interrogation device being positioned close to a conveyor belt or the like on which moving record carriers are passing conveying in accordance with bodily destination marks, see B65G47/46, sorting of objects carrying identity markings, see B07C5/34

Abstract

An electronic label reading system is disclosed having an interrogator including a transmitter for generating an interrogation signal and a receiver for detecting and decoding a reply signal. The system also has an interrogation field creation means including a transmitter antenna connected to the transmitter for generating from the interrogation signal an interrogation electromagnetic field through which objects possessing code responding labels may pass. The code responding labels include label receiving antennas for receiving from the interrogation field a label interrogation signal, means for generating label reply signals, and means for generating from the label reply signals, reply electromagnetic fields. The system also has a receiver antenna connected to the receiver for receiving the reply signals from the label reply fields. The system is arranged so that the interrogation field and label reply fields provide a communication channel from the labels to the interrogator, and the interrogator includes means for signalling to the labels condition information indicative of the condition of the communication channel.

Claims

1. An electronic label reading system including:

an interrogator including a transmitter for generating an interrogation signal and a receiver for detecting and decoding a reply signal;

an interrogation field creation means including a transmitter antenna connected to said transmitter for generating from said interrogation signal an interrogation electromagnetic field through which objects possessing code responding labels may pass;

said code responding labels including label receiving antennas for receiving from said interrogation field a label interrogation signal, means for generating label reply signals, and means for generating from said label reply signals, reply electromagnetic fields;

a receiver antenna connected to said receiver for receiving said reply signals from said label reply fields;

wherein said interrogation field and label reply fields provide a communication channel from said labels to said interrogator, and said interrogator includes means for signalling to said labels condition information indicative of the condition of said communication channel.

2. An electronic label reading system as claimed in claim 1 wherein said condition information is indicative of collisions between reply signals.

3. An electronic label reading system as claimed in claim 1 or 2 wherein said condition information is indicative of errors in decoding of reply signals.

4. An electronic label reading system as claimed in claim 1, 2 or 3 wherein said condition information is indicative of which labels are intended to reply.

5. An electronic label reading system as claimed in any one of the preceding claims wherein said condition information is indicative of strength of interrogation signals received by labels.

6. An electronic label reading system as claimed in any one of the preceding claims wherein said condition information is indicative of absence of a reply signal in a predetermined interval.

7. An electronic label reading system as claimed in any one of claims 2 to 6 wherein said condition information is signalled at the conclusion of a label reply signal.

8. An electronic label reading system as claimed in any one of claims 2 to 6 to wherein said condition information is signalled during a predetermined gap in signalling from a label.

9. An electronic label reading system as claimed in any one of the preceding claims wherein said label reply signal contains a precursor portion separated from the remaining portion of the reply signal by a predetermined gap.

10. An electronic label reading system as claimed in any one of the preceding claims wherein said label reply signal contains data indicative of strength of the interrogation signal experienced by the label.

11. An electronic label reading system as claimed in claim 9 or claim 10 when appended to claim 9 wherein data indicative of strength of the interrogation signal experienced by said label is in the precursor portion of the reply signal, or the remaining portion of the reply signal, or both.

12. An electronic label reading system as claimed in any one of the preceding claims wherein said reply signal is modulated onto the interrogation carrier or onto a sub-carrier.

13. An electronic label reading system as claimed in claim 12 wherein different modulations are used in the precursor portion and the remaining portion of the reply signal.

14. An electronic label reading system as claimed in claim 12 wherein information in said precursor portion indicates the modulation to be used in said remaining portion of the reply signal.

15. An electronic label reading system as claimed in claim 9 wherein the structure of said precursor portion follows rules whereby precursor signals with different information content combine in said communication channel to produce a violation of said rules.

16. An electronic label reading system as claimed in claim 1 wherein reply signals occupy time slots which are determined within said labels according to rules which are known to the interrogator.

17. An electronic label reading system as claimed in claim 1 wherein reply signals occupy time slots which are determined by interrogator signalling.

18. An electronic label reading system as claimed in claim 16 or 17 wherein signals from the interrogator cause labels to close time slots which contain no reply signals or contain colliding reply signals and cause labels to commence the timing of new reply slots.

19. An electronic label reading system as claimed in claim 1 wherein labels have predetermined periods in which said labels enter a listening mode during which there is no label signalling and during which labels seek to detect interrogator signals.

20. An electronic label reading system as claimed in claim 19 wherein labels contain a rectifier system for interrogator signals and employ in said rectifier systems in said listening periods a lower reservoir capacitance than they employ in their reply periods.

21. An electronic label reading system as claimed in claim 16 or 17 wherein labels employ a number of reply slots in a reply round, and offer their replies once per reply round until successfully read.

22. An electronic label reading system as claimed in claim 21 wherein interrogator commands cause variation of the number of reply slots in a reply round.

23. An electronic label reading system as claimed in claim 5 or claim 10 when appended to claim 5 wherein labels make a record of said reply strength of interrogation signal, and wherein a label ceases to reply in further rounds when it receives from said interrogator a signal containing the same strength information as was used by said label in its last reply signal.

24. An electronic label reading system as claimed in claim 22 wherein said variation occurs adaptively in response to observed history of condition of said communication channel.

25. An electronic label reading system as claimed in any one of the preceding claims wherein said interrogator signals to labels reply enabling signals before said labels are enabled to reply.

26. An electronic label reading system as claimed in claim 25 wherein said reply enabling signals can take forms compatible with jurisdictional regulations relating to electromagnetic emissions.

27. An electronic label reading system as claimed in claim 25 wherein said reply enabling signals contain parameters which regulate subsequent label behaviour.

28. An electronic label reading system as claimed in claim 25 wherein said reply enabling signals cause labels either to reply after a delay or to reply immediately.

29. An electronic label reading system as claimed in any one of the preceding claims wherein signals received by a label are interpreted by said label according to a context of its current operation.

30. An electronic label reading system as claimed in claim 25 wherein said interrogator signals include reply enabling signals or reply acknowledgment signals.

31. An electronic label reading system as claimed in claim 30 wherein said reply enabling signals are distinguished from said reply acknowledgement signals.

32. An electronic label reading system as claimed in claim 29 wherein a single dip in amplitude of the interrogation signal can be interpreted by a label as a timing signal or as a reply slot closure signal.

33. An electronic label reading system as claimed in claim 21 or 23 wherein labels resume replying on receiving an error signal from the interrogator.

34. An electronic label reading system as claimed in claim 21 or claim 30 when appended to claim 21 wherein labels resume replying in a further reply round if an error is detected in an acknowledgment signal from the interrogator.

35. An electronic label reading system as claimed in any one of the preceding claims wherein labels fall silent while one of them is being programmed.

36. An electronic label reading system as claimed in claim 21 or 33 wherein an error signal from the interrogator indicates that there was error in decoding the most recently received reply signal, and any label which replied in that time slot resumes replying in a further round.

37. An electronic label reading system as claimed in claim 21 or 33 wherein an error signal from the interrogator indicates that there was error in decoding the reply signal received in the slot prior to that of the most recently received reply signal, and any label which replied in that time slot resumes replying in another round.

38. An electronic label reading system as claimed in any one of the preceding claims wherein the interrogator, after decoding a reply signal, subtracts an amplitude and phase weighted reconstruction of the reply signal which corresponds to the decoded signal from a record which it has made of the entire reply and determines from the results whether there has been a collision between reply signals from different labels.

39. An electronic label reading system as claimed in claim 25 wherein signals from the interrogator determine which labels of all labels present in the interrogation field are enabled for replying or for further communication between themselves and the interrogator.

40. An electronic label reading system as claimed in claim 39 wherein a single label is selected for programming.

41. An electronic label reading system as claimed in any one of the preceding claims wherein a label is programmed through a dialog between interrogator and label in which said label provides timing signals to said interrogator and said interrogator provides data to said label.

42. An electronic label reading system as claimed in claim 16 or 17 wherein variation of the direction of the interrogation field occurs after a predetermined number of time slots.

43. An electronic label reading system as claimed in claim 42 wherein the behaviour of labels is regulated by status information maintained within the labels, and said labels contain memory cells which preserve said status information during the period of variation of field direction, or period of movement of said label through a region of weak interrogation field.

44. An electronic label reading system as claimed in any one of the preceding claims wherein the label reply signals contain data useful for theft detection.

45. An electronic label reading system as claimed in any one of the preceding claims wherein the interrogator signals via pulses and varies during a signalling period the rates of said pulses to comply with jurisdictional regulations relating to electromagnetic emissions.

46. An electronic label reading system as claimed in any one of the preceding claims wherein spaces are inserted in interrogator signalling strings to improve uniformity of the spectrum of interrogator signalling.

47. An electronic label reading system substantially as herein described with reference to the accompanying drawings.