Surface acoustic wave identification tag having an interdigital transducer adapted for code discrimination and methods of operation and manufacture thereof

• US 20040075361A1
• Filed: 10/18/2002
• Published: 04/22/2004
• Est. Priority Date: 10/18/2002
• Status: Active Grant

• Current Assignee: RF Saw Components Incorporated
• Original Assignee: RF Saw Components Incorporated
• Inventors: Hartmann, Clinton S.
• Granted Patent: US 6,759,789 B2
• Time in Patent Office: Days
• US Class Current: 310/313R
• CPC Class Codes: G06K 19/067 Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
• CPC Class Codes: G06K 19/0675 the resonating marks being of the surface acoustic wave [SAW] kind SAW devices per se H03H9/64
• CPC Class Codes: H03H 9/6406 Filters characterised by a particular frequency characteristic
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

A surface acoustic wave (SAW) identification tag having a coded transducer and methods of operating and manufacturing the tag. In one embodiment the tag includes: (1) a piezoelectric substrate having a number of reflectors distributed among a group of slots arranged by both pulse position and phase position on the substrate for encoding a number by pulse and phase position; and (2) a SAW transducer located on the substrate for generating a coded interrogation pulse.

Claims

1. A surface acoustic wave (SAW) identification tag having a coded transducer, comprising:

a piezoelectric substrate having a number of reflectors distributed among a group of slots arranged by both pulse position and phase position on said substrate for encoding a number by pulse and phase position; and

a SAW transducer located on said substrate for generating a coded interrogation pulse.

2. The SAW identification tag as recited in claim 1 wherein said SAW transducer generates said coded interrogation pulse using phase shift keying.

3. The SAW identification tag as recited in claim 1 wherein said SAW transducer generates said coded interrogation pulse using frequency shift keying.

4. The SAW identification tag as recited in claim 1 wherein said SAW transducer generates said coded interrogation pulse is coded with a Barker code sequence.

5. The SAW identification tag as recited in claim 1 wherein said coded interrogation pulse is associated with a family of objects.

6. The SAW identification tag as recited in claim 1 further comprising an associated SAW identification tag reader for identification of said coded interrogation pulse.

7. The SAW identification tag as recited in claim 6 wherein said reflected pulse is identified by using code division multiplexing.

8. A method of operating a surface acoustic wave (SAW) identification tag having a coded transducer, comprising:

exciting a SAW transducer located on a piezoelectric substrate to produce a coded interrogation pulse, said coded interrogation pulse reflecting from reflectors distributed by both pulse position and phase position among a group of slots arranged on said substrate; and

selecting and demodulating a reflected pulse from said coded interrogation pulse to yield a number encoded by both pulse position and phase position.

9. The method as recited in claim 8 wherein said SAW transducer uses phase shift keying to generate said coded interrogation pulse.

10. The method as recited in claim 8 wherein said SAW transducer used frequency shift keying to generate said coded interrogation pulse.

11. The method as recited in claim 8 wherein said coded interrogation pulse is coded with a Barker code sequence.

12. The method as recited in claim 8 wherein said coded interrogation pulse is associated with a family of objects.

13. The method as recited in claim 8 further comprising associating a SAW identification tag reader with said SAW identification tag for said selecting and demodulating.

14. The method as recited in claim 13 wherein said reflected pulse is identified by using code division multiplexing.

15. A method of manufacturing a surface acoustic wave (SAW) identification tag having a coded transducer, comprising:

depositing a number of reflectors on a piezoelectric substrate such that said reflectors are distributed among a group of slots arranged by both pulse position and phase position for encoding a number by pulse and phase position; and

forming a SAW transducer located on said substrate for generating a coded interrogation pulse.

16. The method as recited in claim 15 wherein said SAW transducer uses phase shift keying to generate said coded interrogation pulse.

17. The method as recited in claim 15 wherein said SAW transducer used frequency shift keying to generate said coded interrogation pulse.

18. The method as recited in claim 15 wherein said coded interrogation pulse is coded with a Barker code sequence.

19. The method as recited in claim 15 wherein said coded interrogation pulse is associated with a family of objects.

20. The method as recited in claim 15 further comprising associating a SAW identification tag reader with said SAW identification tag for said selecting and demodulating.