Scott L Rhodes

US Patent:

8049432, Nov 1, 2011

Filed:

Sep 5, 2008

Appl. No.:

12/205385

Inventors:

Mark S. Taipale - Harleysville PA, US
Scott E. Rhodes - Sharpsburg GA, US

Assignee:

Lutron Electronics Co., Inc. - Coopersburg PA

International Classification:

H05B 41/24
H05B 37/02

US Classification:

315282, 315283, 315291

Abstract:

An electronic ballast for driving a gas discharge lamp comprises a measurement circuit for measuring a lamp current flowing through the lamp and a lamp voltage produced across the lamp. The ballast comprises a first winding magnetically coupled to a main transformer of an inverter circuit, and a second winding magnetically coupled to a resonant inductor of a resonant tank circuit. The first and second windings are coupled in series electrical connection to generate a voltage representative of the magnitude of the lamp voltage. The ballast further comprises a current transformer having primary windings coupled in series with the electrodes of the lamp. The measurement circuit integrates the current conducted through secondary windings of the current transformer only during every other half-cycle of the lamp voltage to generate a control signal representative of the magnitude of the lamp current that is in-phase with the lamp voltage.