Anti-collision interrogation pulse focusing system for use with multiple surface acoustic wave identification tags and method of operation thereof

• US 7,084,768 B2
• Filed: 03/21/2002
• Issued: 08/01/2006
• Est. Priority Date: 03/21/2002
• Status: Expired due to Fees

• Current Assignee: RF Saw Components Incorporated
• Original Assignee: RF Saw Components Incorporated
• Inventors: Hartmann, Clinton S., Claiborne, Lewis T.
• Primary Examiner(s): MULLEN, THOMAS J
• Application Number:
  US10/103,650
• Publication Number:
  US 20030179077A1
• Time in Patent Office: 1,594 Days
• Field of Search: 340/572.7, 340/572.1, 340/572.4, 340/10.2, 310/313.R, 310/313.D, 342/42, 342/44, 342/51, 343/757, 367/138
• US Class Current: 340/572.7
• CPC Class Codes: G01S 13/755 using delay lines, e.g. acoustic delay lines
• 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 7/10029 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 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions

Abstract

The present invention provides a system for avoiding code collisions from multiple SAW identification tags and a method of operating such system. In one embodiment the invention provides for (1) focusing an interrogation pulse to within a defined space; and (2) discriminating between coded responses returned from tags located within such defined space.

Claims

1. A system for avoiding code collisions from multiple SAW identification tags, comprising:

a directing means for directing an interrogation pulse having a circular polarity toward said tags, said interrogation pulse generating a corresponding SAW in each of said tags that travels a preselected direction; and

a receiving means for recieving coded responses from only ones of said tags responding to said interrogation pulse.

2. The system as described in claim 1 wherein said circular polarity is clockwise.

3. The system as described in claim 1 wherein said circular polarity is counterclockwise.

4. The system as described in claim 1 further comprising using a hollow cylindrical waveguide to direct said interrogation pulse.

5. The system as described in claim 4 wherein said waveguide is metallic.

6. The system as described in claim 1 further comprising using a solid cylindrical waveguide to direct said interrogation pulse.

7. The system as described in claim 6 wherein said waveguide is a dielectric.

8. The system as described in claim 6 wherein said waveguide has a metallic outer surface.

9. The system as described in claim 1 further comprising a reflector to direct said interrogation pulse.

10. The system as described in claim 9 wherein said reflector is selected from the group consisting of:

a circular reflector;

a curved reflector;

a parabolic reflector;

a re-entrant cavity; and

an elliptical reflector.

11. The system for avoiding code collisions from multiple SAW identification tags, comprising:

a directing means for directing an interrogation pulse having a circular polarity toward said tags, said interrogation pulse generating a corresponding SAW in each of said tags that travels a preselected directionwherein said tags can be turned off; and

a receiving means for recieving coded responses from only ones of said tags responding to said interrogation pulse.

12. The system as described in claim 11 wherein a transducer is used to turn off said tags.

13. The system as described in claim 11 wherein an absorbing reflector is used to turn off said tags.