| 摘要 |
A ballast (10) for powering at least one gas discharge lamp (20) having lamp filaments (22,24) comprises an inverter (200), an output circuit (300), a filament heating control circuit (400), and a dimming control circuit (500). Filament heating control circuit (400) is coupled to the dimming control circuit and at least one of the inverter and the output circuit. During operation, filament heating control circuit (400) controls the inverter and output circuit such that heating of the lamp filaments is provided during a preheat mode th at occurs prior to ignition of the lamp, and during a dimming mode that optionally occurs after ignition of the lamp and that includes operating the lamp at a current level that is substantially less than a rated normal operating curre nt of the lamp. No heating of the lamp filaments is provided during a full-light mode that occurs after ignition of the lamp and that includes operating the lamp at a current level that is substantially equal to the rated normal operating current of the lamp.
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