| 摘要 |
An electronic ballast for a gas discharge lamp has a power source section for receiving a commercial AC to provide a DC voltage, and an inverter section, in response to a pair of switching driving signals, for switching and transforming an output voltage of the power source section at a high speed as an AC power source that is supplied to the gas discharge lamp. For controlling the switching of the inverter section, an inverter controlling section generates a pair of switching driving signals respectively having a predetermined dead time in a switching-ON time interval with a phase difference of 180 degrees from each other to supply them to the inverter section. The inverter controlling section embodies an analog-based system in controlling the gradual shifting of the frequencies of the switching driving signals, which drive the inverter section from an optional frequency f1 to another frequency f2 in accordance with the time and the periodical repetition of the frequency shift, to stably light the gas discharge lamp by preventing the flame fluctuation or acoustic resonance. The inverter controlling section further has circuits for maintaining the constant output, controlling the starting and for performing various protecting operations. An auxiliary power source section uses the output voltage of the power source section to provide an auxiliary power source required for the inverter controlling section.
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