Object identification system employing pulsed magnetic field-stimulated, tag-embedded transponder

• US 6,170,748 B1
• Filed: 09/24/1998
• Issued: 01/09/2001
• Est. Priority Date: 01/06/1997
• Status: Expired due to Term

• Current Assignee: Zebra Technologies Corporation
• Original Assignee: Widata Corporation (Zebra Technologies Corporation)
• Inventors: Belcher, Donald K., Boyd, Robert W., Hash, Ronald J.
• Primary Examiner(s): Lee, Michael G.
• Application Number:
  US09/159,554
• Time in Patent Office: 838 Days
• Field of Search: 235/451, 235/375, 235/383, 235/385, 235/472.01, 235/492, 340/551, 340/571, 340/572
• US Class Current: 235/451
• CPC Class Codes: G06K 7/083 inductive G06K7/10336 takes precedence

Abstract

An object orientation-independent information storage and retrieval system ‘tags’ an object with a compact, strip-embedded transponder containing object identification information. The transponder remains unpowered until the tagged object passes through a pulsed time-varying magnetic field generated by a tag reader. In response to a transponder coil sensing this interrogation magnetic field, the transponder extracts and stores energy from the incident field, powering up the transponder and stimulating the emission of an alternating magnetic field reply burst encoded with information stored in memory. The reply burst has the same frequency as the interrogating magnetic field burst, and is emitted by the transponder coil prior to receipt of the next interrogation burst.

Claims

1. A method of storing and retrieving information representative of at least one characteristic of an object comprising the steps of:

(a) attaching to said object a normally unpowered transponder having programmable memory for storing said information representative of at least one characteristic of said object;

(b) generating a magnetic field burst signal containing a plurality of magnetic field cycles of a prescribed magnetic field variation frequency, such that said magnetic field burst signal impinges upon said transponder;

(c) in response to receiving said magnetic field burst generated in step (b), causing said transponder to be powered from energy contained in said magnetic field burst signal; and

(d) during a prescribed interval of time subsequent to receipt of said magnetic field burst in step (c), causing said transponder to emit a response magnetic field burst containing a plurality of cycles of said frequency, said prescribed interval of time being associated with information stored in said programmable memory; and

wherein

step (b) comprises repetitively generating said magnetic field burst signal at successive burst intervals spaced apart in time by quiescent intervals therebetween;

step (c) comprises storing energy contained in received successive magnetic field burst signals; and

step (d) comprises emitting successive response magnetic field bursts during respective intervals of time between said successive magnetic field bursts received in step (c), each respective interval of time being delayed relative to termination of an immediately preceding received magnetic field burst by a delay interval defined by information accessed from said programmable memory.

2. A method of storing and retrieving information representative of at least one characteristic of an object comprising the steps of:

(a) attaching to said object a normally unpowered transponder having programmable memory for storing said information representative of at least one characteristic of said object;

(b) generating a magnetic field burst signal containing a plurality of magnetic field cycles of a prescribed magnetic field variation frequency, such that said magnetic field burst signal impinges upon said transponder;

(c) in response to receiving said magnetic field burst generated in step (b), causing said transponder to be powered from energy contained in said magnetic field burst signal; and

(d) during a prescribed interval of time subsequent to receipt of said magnetic field burst in step (c), causing said transponder to emit a response magnetic field burst containing a plurality of cycles of said frequency, said prescribed interval of time being associated with information stored in said programmable memory; and

wherein

step (d) comprises, during a prescribed portion of a response window subsequent to receipt of said magnetic field burst in step (c), causing said transponder to emit a response magnetic field burst containing a plurality of cycles of said frequency, said prescribed portion of said response window being associated with information to be transmitted from said transponder during said response window.

3. A method according to claim 2, wherein step (d) comprises encoding information to be transmitted during said response window in terms of the phase of said plurality of cycles of said response magnetic field burst.

4. A method of storing and retrieving information representative of at least one characteristic of an object comprising the steps of:

(a) attaching to said object a normally unpowered transponder having programmable memory for storing said information representative of at least one characteristic of said object;

(b) generating a magnetic field burst signal containing a plurality of magnetic field cycles of a prescribed magnetic field variation frequency, such that said magnetic field burst signal impinges upon said transponder;

(c) in response to receiving said magnetic field burst generated in step (b), causing said transponder to be powered from energy contained in said magnetic field burst signal; and

(d) during a prescribed interval of time subsequent to receipt of said magnetic field burst in step (c), causing said transponder to emit a response magnetic field burst containing a plurality of cycles of said frequency, said prescribed interval of time being associated with information stored in said programmable memory; and

wherein

said transponder includes a coil,

step (c) comprises sensing said magnetic field burst generated in step (b) by way of said coil,

step (d) comprises causing said transponder to emit said response magnetic field burst by way of said coil; and

said transponder coil is coupled in circuit with a plurality of energy storage devices that extract and store power to operate said transponder, and provide for emission of said response magnetic field burst, from energy contained in said received successive magnetic field burst signals.

5. A method according to claim 4, wherein step (d) comprises controllably discharging energy stored in one of said energy storage devices through said coil during said prescribed interval of time subsequent to receipt of said magnetic field burst in step (c), and thereby cause said transponder to emit said response magnetic field burst containing a plurality of cycles of said frequency.

6. A method of storing and retrieving information representative of at least one characteristic of an object comprising the steps of:

(a) attaching to said object a normally unpowered transponder having programmable memory for storing said information representative of at least one characteristic of said object;

(b) generating a magnetic field burst signal containing a plurality of magnetic field cycles of a prescribed magnetic field variation frequency, such that said magnetic field burst signal impinges upon said transponder;

(c) in response to receiving said magnetic field burst generated in step (b), causing said transponder to be powered from energy contained in said magnetic field burst signal;

(d) during a prescribed interval of time subsequent to receipt of said magnetic field burst in step (c), causing said transponder to emit a response magnetic field burst containing a plurality of cycles of said frequency, said prescribed interval of time being associated with information stored in said programmable memory; and

(e) receiving said response magnetic field burst emitted in step (d) and recovering said information; and

wherein

step (b) comprises generating said magnetic field burst signal by way of a magnetic field coil arrangement that is configured to produce a magnetic field intercepting said transponder irrespective of the orientation of said transponder, and wherein step (e) comprises receiving said response magnetic field burst emitted in step (d) by way of said magnetic field coil arrangement.

7. A method of storing and retrieving information representative of at least one characteristic of an object comprising the steps of:

(a) attaching to said object a normally unpowered transponder having programmable memory for storing said information representative of at least one characteristic of said object;

(b) generating a magnetic field burst signal containing a plurality of magnetic field cycles of a prescribed magnetic field variation frequency, such that said magnetic field burst signal impinges upon said transponder;

(c) in response to receiving said magnetic field burst generated in step (b), causing said transponder to be powered from energy contained in said magnetic field burst signal;

(d) during a prescribed interval of time subsequent to receipt of said magnetic field burst in step (c), causing said transponder to emit a response magnetic field burst containing a plurality of cycles of said frequency, said prescribed interval of time being associated with information stored in said programmable memory; and

(e) receiving said response magnetic field burst emitted in step (d) and recovering said information; and

wherein

wherein step (b) comprises generating said magnetic field burst signal by way of a magnetic field coil arrangement supported in a hand-portable housing, and wherein step (e) comprises receiving said response magnetic field burst emitted in step (d) from said magnetic field coil arrangement and recovering said information by way of signal processing circuitry coupled thereto and installed in said hand-portable housing.

8. A method of storing and reading information associated with an object comprising the steps of:

(a) providing said object with a tag containing a normally unpowered transponder that contains memory in which said information is stored;

(b) causing a magnetic field burst containing a plurality of cycles of an alternating magnetic field to be incident upon said tag during successive spaced apart intervals in time; and

(c) for each magnetic field burst incident upon said tag in step (b), extracting energy therefrom for powering said transponder and stimulating said transponder to emit an alternating magnetic field reply burst that is encoded with a portion of said information stored in memory, a respective magnetic reply burst having a frequency corresponding to that of said alternating magnetic field, and being transmitted prior to receipt of the next magnetic field of step (b); and

wherein

step (c) comprises, during a prescribed portion of a response window subsequent to receipt of said magnetic field burst incident upon said tag in step (b), causing said transponder to emit a response magnetic field burst containing a plurality of cycles of said frequency, said prescribed portion of said response window being associated with information to be transmitted from said transponder during said response window.

9. A method according to claim 8, further including the step (d) of receiving said response magnetic field burst emitted by said transponder in step (c), and recovering said information.

10. A method according to claim 8, wherein said transponder includes a coil, and wherein step (c) comprises sensing said magnetic field burst generated in step (b) by way of said coil, and causing said transponder to emit said response magnetic field burst by way of said coil.

11. A method of storing and reading information associated with an object comprising the steps of:

(a) providing said object with a tag containing a normally unpowered transponder that contains memory in which said information is stored;

(b) causing a magnetic field burst containing a plurality of cycles of an alternating magnetic field to be incident upon said tag during successive spaced apart intervals in time; and

(c) for each magnetic field burst incident upon said tag in step (b) extracting energy therefrom for powering said transponder and stimulating said transponder to emit an alternating magnetic field reply burst that is encoded with a portion of said information stored in memory, a respective magnetic reply burst having a frequency corresponding to that of said alternating magnetic field, and being transmitted prior to receipt of the next magnetic field of step (b); and

wherein

step (b) comprises generating said magnetic field burst signal by way of a magnetic field coil arrangement that is configured to produce a magnetic field intercepting said transponder irrespective of the orientation of said transponder, and wherein step (d) comprises receiving said response magnetic field burst emitted in step (c) by way of said magnetic field coil arrangement.

12. A system for storing and retrieving information representative of at least one characteristic of an object comprising:

a tag that is attachable to said object and contains a normally unpowered transponder having memory for storing said information, said normally unpowered transponder being powered from energy contained in a magnetic field burst signal incident thereon; and

a reader that is operative to generate said magnetic field burst signal containing a plurality of magnetic field cycles of a prescribed magnetic field variation frequency, such that said magnetic field burst signal impinges upon said transponder irrespective of the orientation of said object relative to said reader; and

wherein

said transponder is operative, during a prescribed interval of time subsequent to receipt of said magnetic field burst generated by said reader to emit a response magnetic field burst containing a plurality of cycles of said frequency, said prescribed interval of time being associated with information stored in said memory, and

said reader is operative to receive said response magnetic field burst emitted by said transponder and recover said information; and

wherein

said reader is operative to repetitively generate said magnetic field burst signal at successive burst intervals spaced apart in time by quiescent intervals therebetween, and wherein said transponder is operative to emit successive response magnetic field bursts during respective intervals of time between said successive magnetic field bursts received thereby, each respective interval of time being delayed relative to termination of an immediately preceding received magnetic field burst by a delay interval defined by information accessed from said programmable memory.

13. A system according to claim 12, wherein said transponder includes a transponder coil that is configured to sense said magnetic field burst generated by said reader, and wherein said transponder is operative to emit said response magnetic field burst by way of said transponder coil.

14. A system according to claim 12, wherein said reader comprises a magnetic field coil arrangement that is configured to produce a magnetic field intercepting said transponder irrespective of the orientation of said transponder.

15. A system according to claim 12, wherein said reader is installed in a hand-portable housing.

16. A system for storing and retrieving information representative of at least one characteristic of an object comprising:

a tag that is attachable to said object and contains a normally unpowered transponder having memory for storing said information, said normally unpowered transponder being powered from energy contained in a magnetic field burst signal incident thereon; and

a reader that is operative to generate said magnetic field burst signal containing a plurality of magnetic field cycles of a prescribed magnetic field variation frequency, such that said magnetic field burst signal impinges upon said transponder irrespective of the orientation of said object relative to said reader; and

wherein

said transponder is operative, during a prescribed interval of time subsequent to receipt of said magnetic field burst generated by said reader to emit a response magnetic field burst containing a plurality of cycles of said frequency, said prescribed interval of time being associated with information stored in said memory, and

said reader is operative to receive said response magnetic field burst emitted by said transponder and recover said information,

said transponder includes a transponder coil that is configured to sense said magnetic field burst generated by said reader, and wherein said transponder is operative to emit said response magnetic field burst by way of s aid transponder coil; and

wherein

said transponder coil is coupled in circuit with a plurality of energy storage devices that extract and store power to operate said transponder, and provide for emission of said response magnetic field burst, from energy contained in said received successive magnetic field burst signals.