High sensitivity radio frequency identification tag

• US 7,893,816 B1
• Filed: 12/10/2004
• Issued: 02/22/2011
• Est. Priority Date: 12/10/2004
• Status: Active Grant

• Current Assignee: NCR Voyix Corporation
• Original Assignee: NCR Corporation
• Inventors: Kwan, Sik Piu
• Primary Examiner(s): Holloway, III; Edwin C
• Application Number:
  US11/009,677
• Time in Patent Office: 2,265 Days
• Field of Search: 340/10.34, 340/10.1, 340/572.1, 340/7.32, 455/343.1
• US Class Current: 340/10.34
• CPC Class Codes: G06K 19/07 with integrated circuit chips
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management

Abstract

Systems and techniques for identification of items using radiofrequency identification (RFID) tags exhibiting a high sensitivity to signals such as signals emitted by an RFID reader. An RFID tag includes an amplification circuit operative to detect and amplify a signal received from an RFID reader, in order to allow for processing of and response to the signal. The amplification circuit may be powered by a battery, suitably a flexible printable battery. Alternative or additional power sources may be used, such as a solar cell or a magnetic coupling, and depending on the design and operation of the tag, these power sources may be used instead of the battery or to recharge the battery if required.

Claims

1. An at least partially self powered radiofrequency identification (RFID) tag for use in an RFID system, the RFID tag comprising:

an antenna for receiving an RFID reader signal from an RFID reader, the RFID reader signal providing power for said RFID tag when the received RFID reader signal is sufficiently strong;

an amplification circuit employing a power source independent of the RFID reader for amplifying the RFID reader signal which is active to produce an amplified signal in a first mode and inactive in a second mode;

an amplifier control circuit for controlling operation of the amplification circuit whereby the amplification circuit is controlled to be active in the first mode if the received RFID reader signal has a level below a predetermined minimum; and

a communication circuit for receiving the amplified signal and sending a response signal to the RFID reader based on the amplified signal in the first mode and for receiving the RFID reader signal and sending a response signal to the RFID reader based thereon in the second mode.

2. The RFID tag of claim 1, wherein the power source comprises a flexible battery to provide power to amplify the RFID signal.

3. The RFID tag of claim 2, wherein the battery is a flexible printable battery.

4. The RFID tag of claim 3, wherein the battery is incorporated into an antenna structure of the tag.

5. The RFID tag of claim 1, wherein the power source is an external power source and the tag includes an interface to the external power source to allow the amplification circuit to be powered by the external power source.

6. The RFID tag of claim 5, further including a rechargeable battery and wherein the interface to the external power source includes a coupling to the battery to allow the battery to be recharged by the external power source.

7. The RFID tag of claim 5, wherein the external power source may be an external light source, a magnetic field, an electrical field or mechanical motion or vibration and wherein the interface to the external power source may be a solar cell for receiving power from the external light source, a magnetic inductive coupling for receiving power from the magnetic field, a capacitive coupling for receiving power from the electrical field or a mechanical transducer for converting the mechanical motion or vibration into electrical power.

8. The RFD tag of claim 1, wherein the amplifier control circuit is operative to receive commands to change the conditions mode of operation of the amplification circuit.

9. The RFID tag of claim 8, wherein the amplifier control circuit is operative to receive commands through an inductive coupling interface.

10. The RFID tag of claim 8, wherein the amplifier control circuit is operative to receive commands through a capacitive coupling interface.

11. A method of radio frequency identification (RFID) communication, comprising the steps of:

receiving an RFID signal from an RFID reader;

determining whether the received RFID signal is below a predetermined minimum;

utilizing power from the received RFID signal to prepare and transmit a response based on the received RFID signal in a first mode;

amplifying the RFID signal to produce an amplified RFID signal, amplification being accomplished using a power source independent of the RFID signal in a second mode when the received RFID signal is below the predetermined minimum;

preparing a response signal based on the amplified RFID signal; and

transmitting the response signal to the RFID reader.

12. The method of claim 11, wherein the power source for amplifying the RFID signal is a flexible battery.

13. The method of claim 11, wherein the power source for amplifying the RFID signal is an external power source.

14. The method of claim 12, further comprising a step of coupling the battery to an external power source for recharging.

15. The method of claim 11, further comprising a step of specifying conditions under which amplification is to be performed.

16. The method of claim 15, wherein amplification is performed at all times an RFID signal is detected, when the RFID signal is below a predetermined strength, or at all times, depending on which conditions have been specified.