| 摘要 |
<p>of the Invention A method and apparatus are provided for operating a fluorescent lamp illumination control system which comprises an AC voltage source for supplying power to an electrical load comprising a standard transformer-ballast unit driving a fluorescent lamp or lamps which have externally heated cathodes, and a power controller, which includes a capacitive synchronous switch formed by an electronic switch and shunt capacitor, for controlling the "on" time of the lamp or lamps to thereby vary the luminance output thereof to values less than the nominal rated value. The invention provides heating of the lamp cathodes prior to arc ignition, provides arc ignition at a lower arc current level than that for full-on operation, and provides for subsequently gradually increasing the arc current after the arc is struck to a value providing the desired illumination level.</p> |
