RFID device detection system and method

• US 7,273,173 B2
• Filed: 05/01/2006
• Issued: 09/25/2007
• Est. Priority Date: 04/03/2003
• Status: Expired due to Term

• Current Assignee: Avery Dennison Retail Information Services LLC (Avery Dennison Corporation)
• Original Assignee: Avery Dennison Corporation
• Inventors: Forster, Ian J.
• Primary Examiner(s): ST CYR, DANIEL
• Application Number:
  US11/414,889
• Publication Number:
  US 20060192002A1
• Time in Patent Office: 512 Days
• Field of Search: 235/451, 235/385, 340/572.7, 340/572.8, 340/572.1, 340/573.4, 340/573.3, 340/572.5, 340/572, 340/573
• US Class Current: 235/385
• 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 7/10346 the antenna being of the far field type, e.g. HF types or dipoles

Abstract

An RFID device detection system includes a proximity locator, which generates an electric field for reading an antennaless RFID device, or for reading other, antennaed RFID devices. An antennaless RFID device includes non-antenna conductive leads coupled to a chip. The proximity locator includes one or more conductors forming a transmission line structure arranged to set up a strong RF electric field in proximity to the locator. The strong RF electric field may be a short-range field that provides significant RF energy only over a relatively short distance, when compared with traditional RF fields that are set up over a relatively large distance. The short-range RF field allows coupling to antennaed and antennaless RFID devices that are near to the proximity locator. The RFID device detection system may be employed in a variety of tasks, including inventory control and theft detection.

Claims

1. A method of detecting RFID devices, comprising:

producing an RF electric field about a transmission line structure by sending an AC signal along at least two transmission lines of the transmission line structure;

powering the RFID devices using the RF electric field; and

detecting the RFID devices using a reader mechanically coupled to the transmission line structure.

2. The method of claim 1, wherein the transmission lines are substantially parallel to one another, with a gap therebetween.

3. The method of claim 1, wherein the RFID devices include antennaless RFID devices.

4. The method of claim 3, wherein the powering the RFID devices and the detecting the RFID devices include powering and detecting while the RFID devices are at least partially within a gap between the transmission lines.

5. The method of claim 4, wherein the transmission lines are substantially parallel to one another.

6. The method of claim 1, wherein the powering includes capacitively coupling the transmission line structure and the RFID devices.

7. The method of claim 1, wherein the powering includes magnetically coupling the transmission line structure and the RFID devices.

8. The method of claim 1, wherein the RFID devices include antennaed RFID devices.