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:
Mar. 01, 1977
Filed:
Dec. 22, 1975
Carlo S Bessone, Cambridge, MA (US);
Frank M Latassa, Magnolia, MA (US);
GTE Sylvania Incorporated, Danvers, MA (US);
Abstract
A ballast for a rapid start fluorescent lamp with heated filaments has a secondary winding supplying lamp current, tertiary windings for supplying heater current to the filaments, and solid state switching circuits in secondary circuits through the filaments. Each switching circuit, which may be integrated with the ballast circuit or connected to a filament within the lamp envelope, comprises two voltage divider resistors having a common junction coupled to the gate of a triac whose primary electrodes are connected in parallel with the voltage divider. The triac is in series with the filament and supplies heating current to the filaments prior to lamp starting. When the lamp starts and conducts rated operating current the voltage divider reduces the voltage at its junction and at the triac gate below triac breakdown level thereby substantially eliminating heater current. BACKGROUND OF THE INVENTION