Identification system for simultaneously interrogated labels

• US 5,523,749 A
• Filed: 09/28/1993
• Issued: 06/04/1996
• Est. Priority Date: 04/03/1991
• Status: Expired due to Term

• Current Assignee: Tagsys Australia Pty Limited
• Original Assignee: Integrated Silicon Design Pty Ltd. (Thales SA)
• Inventors: Turner, Leigh H., Cole, Peter H.
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): MERZ, EDWARD W
• Application Number:
  US08/122,526
• Time in Patent Office: 980 Days
• Field of Search: 340/825.54, 340/572, 342/44, 342/51
• US Class Current: 340/10.34
• CPC Class Codes: B07C 3/18 Devices or arrangements for indicating destination, e.g. by code marks applying data to information carriers G06K1/12
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07758 arrangements for adhering the record carrier to further objects or living beings, functioning as an identification tag
• CPC Class Codes: G06K 19/07779 the inductive antenna being a coil
• CPC Class Codes: G06K 19/07783 the coil being planar
• CPC Class Codes: G06K 19/07786 the antenna being of the HF type, such as a dipole
• 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 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22
• 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 7/10435 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
• CPC Class Codes: G07B 15/00 Arrangements or apparatus for collecting fares, tolls or entrance fees at one or more control points handling coins or valuable papers, e.g. banknotes, G07D; apparatus for vending or hiring articles or services activated by coins, credit cards, paper currency or the like G07F7/00, G07F17/00
• CPC Class Codes: G08B 13/2417 having a radio frequency identification chip
• CPC Class Codes: G08B 13/2431 Tag circuit details
• CPC Class Codes: G08B 13/2434 Tag housing and attachment details
• CPC Class Codes: G08B 13/2437 Tag layered structure, processes for making layered tags
• CPC Class Codes: G08B 13/2448 Tag with at least dual detection means, e.g. combined inductive and ferromagnetic tags, dual frequencies within a single technology, tampering detection or signalling means on the tag
• CPC Class Codes: G08B 13/2462 Asset location systems combined with EAS inventory, tracking, logistic G06Q10/00; entrance control systems G07C9/00
• CPC Class Codes: G08B 13/2471 Antenna signal processing by receiver or emitter
• CPC Class Codes: G08B 13/2474 : Antenna or antenna activator geometry, arrangement or layout loop antennae H01Q1/22
• CPC Class Codes: G08B 13/2485 : Simultaneous detection of multiple EAS tags
• CPC Class Codes: H01Q 7/00 : Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
• CPC Class Codes: H01Q 9/285 : Planar dipole H01Q9/065 takes precedence; patch antenna H01Q9/0407

Abstract

An identification system having an electronic label for processing articles such as baggage or carrier cargo. The system uses the principle of electromagnetic communication in which an interrogator containing a transmitter generates an electromagnetic field through which the electronic label containing a label receiving antenna may pass. The electronic label is attached to the article being processed and includes means for sensing the electromagnetic field and means for generating intermittently repeated label reply signals. The system includes a receiver for detecting and decoding the label reply signal. The electronic label replies intermittently as long as it is within the electromagnetic field, and the field is maintained for a period of time which is greater than the time interval between the intermittently repeated label replies. The electronic label also includes means for determining the interval between the intermittently repeated label reply signals without reference to timing signals external to the label. The interval between label reply signals varies from label to label and is greater than the time required for a label reply.

Claims

1. An identification and telemetry system comprising:

an interrogator including a transmitter for generating an interrogation electromagnetic field through which code responding labels may pass;

at least one code responding label including a label receiving antenna, means for sensing the interrogation electromagnetic field and means for generating intermittently repeated label reply signals; and

a receiver for detecting and decoding said label reply signals;

said at least one label replying intermittently as long as said at least one label is within the interrogation electromagnetic field, and

said interrogation electromagnetic field being maintained for a period of time greater than the time interval between the intermittently repeated label replies;

said at least one label including means within the label for determining the interval between the intermittently repeated label reply signals for said at least one label without reference to timing signals external to the label, and

said interval varying from label to label and being greater than the time required for said label reply.

2. An identification and telemetry system as claimed in claim 1 wherein repeated replies from a plurality of labels present at one time within the interrogation field do not permanently overlap in time.

3. An identification and telemetry system as claimed in claim 1 wherein relative positions of replies from a plurality of labels present at one time within the interrogation field vary as a result of the accumulation of different intervals between replies.

4. An identification and telemetry system as claimed in claim 1 wherein the first reply from a label occurs as soon as that label enters a region of the interrogation electromagnetic field strong enough for operation of that label.

5. An identification and telemetry system as claimed in claim 1 wherein said at least one label includes oscillator and logic circuits within the label for determining said interval between replies.

6. An identification and telemetry system as claimed in claim 1 wherein said at least one label comprises an oscillator within the label for regulating said interval between replies from the label, said oscillator having a voltage dependent output frequency.

7. An identification and telemetry system as claimed in claim 6 wherein the voltage supplied to said oscillator is dependent upon the strength of the interrogation field at the position of the label.

8. An identification and telemetry system as claimed in claim 7 further comprising means for varying interrogation power to allow variation of the interval between replies from a label.

9. An identification and telemetry system as claimed in claim 1 wherein said interval between replies from a label is determined by a unique label serial number.

10. An identification and telemetry system as claimed in claim 1 wherein said interval between replies from a label varies over time in accord with a pseudo-random sequence.

11. An identification and telemetry system as claimed in claim 10 wherein said pseudo random sequence is determined by information present in the label.

12. An identification and telemetry system as claimed in claim 11 wherein information to be provided as the reply code is used also to determine said pseudo random sequence.

13. An identification and telemetry system as claimed in claim 10 wherein said pseudo random sequence is determined by information other than information in the label reply.

14. An identification and telemetry system as claimed in claim 1 wherein said at least one label includes circuits within the label that present an impedance to the label receiving antenna which varies with the signal level received by that antenna so as to allow the label to operate correctly over a relatively large range of interrogation signal strength.