The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 29, 2002
Filed:
Jun. 20, 1994
Michael L. Beigel, Corona, CA (US);
Nathaniel Polish, New York, NY (US);
Steven R. Frank, Golden, CO (US);
Robert E. Malm, Pacific Palisades, CA (US);
Avid Marketing, Inc., Norco, CA (US);
Abstract
The coil in the reader that is used to establish an alternating magnetic field is transformer-coupled through capacitors to a push-pull driving circuit consisting of four field-effect transistors connected in a bridge arrangement. The coil, capacitors, and coupling circuitry are maintained in a tuned condition by continually adjusting either the driving frequency, the coil inductance, or the capacitor capacitance during communications. A tag utilizes a coil to couple with the reader's alternating magnetic field and a capacitor to resonate the coil, thereby extracting power from the field more efficiently. Transformer coupling of the coil and capacitor is utilized for improved impedance matching. The coil, capacitor, and coupling circuitry can be maintained in a tuned condition by continually adjusting either the coil inductance, or the capacitor capacitance during communications. Certain configurations of the system may require that tuning maintenance be discontinued during the transmission of data.