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. 03, 2000
Filed:
Oct. 16, 1998
Mihail S Moisin, Brookline, MA (US);
Abstract
A ballast includes a resonant inverter circuit which limits the voltage applied to a lamp when it fails to light. In one embodiment, the inverter includes first and second switching element having conduction states controlled by respective first and second control circuits. The second control circuit includes a third switching element which controls the conduction state of the second switching element. An end of life circuit includes a first threshold circuit coupled to the third switching element for disabling the inverter when the voltage applied to the lamp becomes greater than a first predetermined threshold. In another embodiment, the second control circuit includes a fourth switching element for controlling a duty cycle of the third switching element and the end of life circuit includes a second threshold circuit. When the lamp voltage becomes greater than a second predetermined threshold, the fourth switching element reduces the duty cycle of the third switching element.