| 摘要 |
A ballast ( 10 ) for powering a lamp load ( 70 ) comprising one or more gas discharge lamps ( 72,74 ) includes an inverter ( 200 ), a resonant output circuit ( 400 ), and a control circuit ( 600 ). During operation of ballast ( 10 ), control circuit ( 600 ) monitors at least one voltage within one or more series resonant circuits of output circuit ( 400 ). When the monitored voltage reaches a specified level, control circuit ( 600 ) directs inverter ( 200 ) to maintain its operating frequency at a present value for a predetermined period of time, so as to allow output circuit ( 400 ) to provide a suitably high voltage for igniting the lamp(s). If the lamp(s) ignite within the predetermined period of time, control circuit ( 600 ) ceases controlling inverter ( 200 ) to maintain its operating frequency at the present value, so as to allow for normal operation of the lamp(s). Control circuit ( 600 ) also provides a lamp stabilization function, in which the inverter operating frequency is prevented from falling below a specified minimum value, and a protective function, in which inverter ( 200 ) is deactivated in response to failure of the lamp(s) to ignite within the predetermined period of time.
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