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. 24, 1991
Filed:
Jan. 24, 1990
Richard M Dunham, Salisbury, NH (US);
Walker Power, Inc., Warner, NH (US);
Abstract
The lamp ballasting apparatus disclosed herein is of the high-frequency switching type which operates from a DC supply and effects pulse-width modulation to control the level of energization of the lamp. A common mode choke interposed between the lamp and the modulating means provides a series inductance opposing rapid common mode changes in the currents flowing through the lamp leads. A fast semiconductor switch is interposed in the lamp circuit. A current transformer inductively linked to the lamp leads generates a control signal having an amplitude which is a function of the difference of the current flowing in the leads and this control signal operates the switch when the current difference rises above a preselected level indicating an arcing condition.