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:
Feb. 23, 1988
Filed:
Jul. 31, 1986
Lucian G Ferguson, Largo, FL (US);
Lincoln H Charlot, Jr, St. Petersburg, FL (US);
Security Tag Systems, Inc., St. Petersburg, FL (US);
Abstract
A batteryless, portable, transponder useful in a tag for a presence detection system. The transponder detects electromagnetic radiation at a first predetermined frequency and responds to said detection by transmitting electromagnetic radiation at a second frequency that is a subharmonic of the first frequency. The transponder includes an amorphous magnetic material component for storing energy from the electromagnetic radiation detected at the first frequency for transmission as the electromagnetic radiation transmitted at the second frequency. In one embodiment the transponder includes a thin, flat ribbon of low coercivity magnetostrictive amorphous magnetic material having a transverse uniaxial magnetic anisotropy defining a magnetomechanical resonant frequency 'f' in accordance with the dimensions of the ribbon, when in the presence of a magnetic bias field of a predetermined intensity, wherein the ribbon responds to the detection of electromagnetic radiation having a frequency '2f' by transmitting electromagnetic radiation at a subharmonic of the frequency '2f'; and means for biasing the ribbon with the predetermined magnetic bias field. In another embodiment, the transponder consists of a single resonant circuit including a nonlinear inductor having a core made of amorphous magnetic material; and a capacitance connected in series with the inductor to define the resonant circuit. The core of the nonlinear inductor includes an elongated thin, flat ribbon of low coercivity amorphous mangetic material. It has been observed that this resonant circuit exhibits a bifurcated frequency-division characteristic in relation to the amplitude of the detected electromagnetic radiation at the first predetermined frequency, whereby additional frequency divisions occur as the amplitude is increased. A coded tag includes two amorphous magnetic material transponders that detect electromagnetic radiation at different frequencies.