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:
Sep. 21, 1993
Filed:
Jan. 02, 1992
William J Roche, Merrimac, MA (US);
GTE Products Corporation, Danvers, MA (US);
Abstract
An adaptor circuit used to enable stable, flicker-free operation of T8-type fluorescent lamps in a lighting fixture which already has a standard two-lamp, series-sequence, 40 watt, rapid-start type ballast installed therein. The adaptor circuit contains an isolation transformer for controlling the voltage supplied by the ballast to the T8-type fluorescent lamps and a frequency selective impedance modifier circuit for controlling the operating current supplied by the ballast to the T8-type fluorescent lamps at preselected frequencies. In one embodiment, the frequency selective impedance modifier circuit substantially eliminates the third harmonic component of the fundamental frequency of the operating current.