Other

Avid Identification Systems, Inc.

Avid Marketing, Inc.

Avid Indentification Systems, Inc.

Gui-Yang Lu

Peter Troesch

Michael F Cruz

Robert E Malm

Sammy E Wooldridge

A passive radio frequency identification (RFID) reader is configured to dynamically vary the Q factor of its resonant antenna coil circuit in order to optimize its performance under different conditions. This RFID reader suitably provides optimal performance for both transponder reading and transponder writing operations, rather than being designed for optimal performance for only one operation or the other, or some fixed compromise between them.

Variable-Q antenna coil circuit for RFID applications

The invention is a radio-frequency identification system consisting of a reader and a tag. The reader comprises a transmit/receive resonant circuit comprising one or more coils, a means for repeatedly driving the transmit/receive resonant circuit with pulses of a periodic signal, a means for obtaining a tag response signal from the transmit/receive resonant circuit, a means for extracting tag information from the tag response signal obtained from the transmit/receive resonant circuit, a receive resonant circuit comprising one or more coils, a means for obtaining a tag response signal from the receive resonant circuit, and a means for extracting tag information from the tag response signal obtained from the receive resonant circuit. The tag comprises a plurality of resonant circuits, a means for recognizing he presence of an interrogating magnetic field, and a means for embedding information to be communicated to the interrogating reader in at least one coil current.

Radio-frequency identification system

The invention is a resonant-circuit structure for enhancing the interrogation range of a radio-frequency identification system. The resonant circuit structure consists of a coil assembly and a capacitor connected in parallel with a resonance frequency equal to the frequency of the interrogating signal of the radio-frequency identification system with which the resonant circuit structure is to operate. The coil assembly and the capacitor are embedded in a structure which provides physical support for the coil assembly and the capacitor and access to a region near the coil assembly.

Resonant-circuit structure

An extended-range reader for use in identifying the tag of an object. The reader includes a winding of conducting wire for generating an interrogating magnetic field. The winding may be either a coil assembly consisting of a plurality of coils spaced at intervals along a common axis or a solenoid. The winding is limited to those having values of D/L less than four where D is the smallest transverse dimension of the winding and L is the length. The winding is adapted to receive a structure within the winding for providing objects a passageway through the winding. The axis of the winding may be either straight or curved. To improve the magnetic field generating capability of the winding, a magnetic shunt encircling the winding can be added. Also included is a structure within the winding for providing objects a passageway through the winding, the structure having openings for object ingress and egress. Where the structure is intended to provide a natural environment for the objects, the structure, except for the openings, can be made pervious or impervious to liquids or gases.

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Upland, CA, United States of America

Gui-Yang Lu