Method and system for miniature passive RFID tags and readers

• US 8,089,344 B1
• Filed: 06/25/2005
• Issued: 01/03/2012
• Est. Priority Date: 06/25/2004
• Status: Active Grant

• Current Assignee: M Afshin Zand
• Original Assignee: M Afshin Zand
• Inventors: Zand, M Afshin
• Primary Examiner(s): Tweel, Jr., John A
• Application Number:
  US11/165,921
• Time in Patent Office: 2,383 Days
• Field of Search: 340/10.2, 340/10.34, 340/10.1, 340/572.1, 340/573.1, 340/539, 340/572.2, 340/572.4, 455/73, 455/75, 455/77
• US Class Current: 340/10.2
• CPC Class Codes: G01S 13/758 using a signal generator powered by the interrogation signal
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: G06K 7/10306 ultra wide band

Abstract

This invention makes possible small size, long range, reliable, low-power, low-cost RFIDs fulfilling the needs of the industry and the roadmap set for RFID, as by Walmart and the DoD. Tag energization and data communication take place by independent means. The invention employs low-power communication means, such as ultra wideband (UWB), for transfer of data between Tag and Reader, and relatively high power narrowband means to remotely energize the Tag. Said means of powering and communication mechanisms, further, are independent of the underlying process, or technology, of implementation of the Microchip on the Tag, as well as from the transceiver technology aboard the Reader. As such, they provide an ideal method and system by which to power and communicate with RFIDs, through cycles of evolution and changes in physical implementation technology.

Claims

1. A method for Radio Frequency Identification (RFID), whereby an RFID Reader remotely energizes a Tag or plurality of Tags by means of a carrier-based signal which may be stationary or hopping and need carry no data, and wherein the means of transmission and reception by which the Tag or a plurality of Tags and the Reader or Readers communicate information is that of an ultra wideband signal only, wherein the ultra wideband signal is pulsed and carrierless, and occupying a minimum bandwidth ranging from tens of Megahertz to five hundred Megahertz, to a maximum bandwidth of several Gigahertz or more, whereby the communication may include reception by a rake receiver in the reader, and wherein the Tag comprises a patch Antenna, and an integrated circuit containing circuitry and means for information processing.

2. The method of claim 1, wherein a narrowband stationary or hopping carrier in the 5.15-5.85 GHz frequency range, or the 2.4-2.4835 GHz range, or the 902-928 MHz range, or the 869.4-869.65 MHz range, or other available frequency range, which need carry no data, is transmitted by the Reader thus energizing the Tag or Tags.

3. The method of claim 1, whereby the carrier-based signal'"'"'s frequency overlaps the ultra wideband signal'"'"'s frequency spectrum or is near that frequency spectrum, thus allowing the Tag to be operational with a single Antenna capable of receiving both the carrier-based stationary or hopping signal and receiving and/or transmitting the ultra wideband signal.

4. The method of claim 1, whereby the Reader employs one or more directional antennae, also known as constant aperture antenna, which intrinsically have gain and may serve one or both of said signals, whereby in the case of the carrier-based signal the power output of the carrier from a Reader may be lowered in proper proportion according to the gain of said directional antenna.

5. The method of claim 1, whereby the physical mechanism by which the RFID Reader performs its function of energization of the RFID Tag resides in a housing or enclosure distinct from and located separately from the physical mechanism by which the RFID Reader communicates information with the RFID Tag or plurality of Tags, thus enabling the placement of multiple energizers strategically where Tags are to be powered and read from or written to.

6. The method of claim 1, whereby the integrated circuit of the Tag employs low forward voltage-drop diodes, or equivalent components, including, but not limited to, Schottky diodes, and/or employs a capacitive charge pump or inductive switching circuit to convert received power from a Reader or energizer to a power supply with useful voltage for its circuitry and the integrated circuit of the Tag employs a zener diode or diodes or equivalent means to regulate and stabilize said voltage for use by the rest of the Tag'"'"'s integrated circuit.

7. The method of claim 1, whereby the integrated circuit of the Tag employs memory, electrically-erasable programmable read-only memory or non-volatile random access memory, to record information it may receive from the Reader or Readers, or to store information at the time of manufacture, and thus be able to retain such information in the absence of power.

8. The method of claim 1, whereby the Reader, receiving ultra wideband information from the Tags, through its ports operates wireless or wireline communication links to other equipment, where said equipment constitutes part of the enterprise system of an organization which may include a factory, warehouse, department store, retail outlet, or offices, for the purpose of relaying information aboard Tag(s) to said system, and communicating between said system and the Tag, wherein said ports and links are separate and distinct from the links between Reader and Tag.

9. The method of claim 1, whereby the RFID Tag employs within its integrated circuit one or more integrated components having radio frequency, analog and digital circuitry and means for processing information, said circuitry and other means comprising the RFID Tag'"'"'s integrated circuit.

10. The method of claim 1, whereby the RFID Tag employs within its integrated circuit, for the purposes of processing data:

memory, logic control, state machine, microcoded engine, microcontroller, central processing unit, digital signal processor.

11. The method of claim 1, wherein the means by which the RFID Tag is, or a plurality of RFID Tags are, energized is augmented or replaced by a solar cell incorporated on the integrated circuit of the RFID Tag or is augmented or replaced by a battery incorporated on the integrated circuit of the RFID Tag.

12. The method of claim 1, wherein the means by which the RFID Tag is, or a plurality of RFID Tags are, energized, where a line of sight is available, is augmented or replaced by a beam of electromagnetic radiation in the infra-red or visible or other available and permissible part of the spectrum.

13. The method of claim 1, wherein the means by which the RFID Tag is, or a plurality of RFID Tags are, energized is augmented by the integrated circuit aboard the RFID Tag incorporating a capacitor for the storage of energy received, for use by the rest of the integrated circuit aboard Tag or for transmission after energization has ceased.

14. The method of claim 1, wherein the system comprised of the RFID Tag or plurality of Tags and the RFID Reader or Readers, by means of communication of a known test signal from Reader to Tag and back, performs measurement of time of flight, allows for a known processing delay until response issues from Tag, determines distance between Reader and Tag by subtraction of said processing delay from half the round-trip time of flight, and multiplication of the result by the speed of light, and by calculation employing proper algorithms involving the solving of simultaneous equations locates the two-dimensional or three-dimensional position of an RFID Tag or Tags desired to be localized, which emitted said test signal.

15. The method of claim 1, wherein the system comprised of the RFID Tag or plurality of Tags and the RFID Reader or Readers, by means of communication of a known test signal from Tag which is then received by Readers, calculates the time difference of arrival of said signal at various Readers and from that information, and speed of light, and by calculation employing proper algorithms involving the solving of simultaneous equations thus locates the two dimensional or three-dimensional position of the RFID Tag or Tags desired to be localized, which emitted said test signal.

16. The method of claim 1, wherein a plurality of RFID Tags communicate information to each other and act as relays for one another and communicate information in a mesh network, thus enabling the networking of Tags in the absence of Readers as well as extending the range possible between a given RFID Reader and a given RFID Tag.

17. The method of claim 11, wherein a plurality of Tags thus energized communicate information to each other and act as relays for one another in a mesh network, thus enabling the networking of Tags in the absence of Readers as well as extending the range possible between a given RFID Reader and a given RFID Tag.

18. The method of claim 12, wherein a plurality of RFID Tags thus energized communicate information to each other and act as relays for one another in a mesh network, thus enabling the networking of Tags in the absence of Readers as well as extending the range possible between a given RFID Reader and a given RFID Tag.

19. The method of claim 13, wherein a plurality of RFID Tags thus energized communicate information to each other and act as relays for one another in a mesh network, thus enabling the networking of Tags in the absence of Readers as well as extending the range possible between a given RFID Reader and a given RFID Tag.

20. The method of claim 10, wherein a plurality of RFID Tags thus energized are able to communicate information to is each other and act as relays for one another in a mesh network, thus enabling the networking of Tags in the absence of Readers as well as extending the range possible between a given RFID Reader and a given RFID Tag.

21. The method of claim 1, wherein possible collisions in transmission to the Reader or Readers from a plurality of RFID Tags that may be energized simultaneously is prevented or minimized by an anti-collision algorithm or protocol with statistical randomized timing of transmissions precoded into the integrated circuit of the Tags and into the Reader for expecting the same, or wherein the RFID reader is able to selectively address or turn off, temporarily or permanently, individual Tags.