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:
Dec. 18, 2001
Filed:
Jun. 10, 1998
Thomas J. Ribarich, Laguna Beach, CA (US);
Talbott M. Houk, Culver City, CA (US);
International Rectifier Corporation, El Segundo, CA (US);
Abstract
A circuit which detects near or below resonance operation of a fluorescent lamp being driven with a half-bridge circuit and which deactivates the half-bridge circuit before any damage to the circuit can result. In the circuit of the present invention, the voltage across a sense resistor disposed either the lower transistor switch and ground, or between the lower lamp filament and ground, is compared against a predetermined reference voltage to generate an output comparison signal. The output comparison signal is gated to the turn-off edge of the lower MOSFET (in the case of the sense resistor disposed between the lower MOSFET and ground) or to the turn-off edge of the upper MOSFET (in the case of the sense resistor between the lower lamp filament and ground) to generate a signal for shutting down the half-bridge circuit in the event of near or below resonance operation of the lamp resonant circuit.