| 摘要 |
PROBLEM TO BE SOLVED: To provide a lamp ballast capable of avoiding acoustic resonance. SOLUTION: This lamp ballast includes a rectifying circuit 32 rectifying an alternating-current power signal into a pulsating direct-current power signal, and a converting circuit 33 electrically coupled to the rectifying circuit 32 for converting the pulsating direct-current power signal into an alternating-current driving signal useful for driving a lamp 4. The pulsating alternating-current power signal has a frequency that is twice that of the alternating-current power signal and is lower than an acoustic resonance frequency range. The alternating-current driving signal has a waveform that varies at a high frequency and has positive and negative cycle envelope segments. Each of the positive and negative cycle envelope segments has a frequency corresponding to that of the pulsating direct-current power signal. The positive and negative cycle envelope segments are mirror images of each other with respect to a time axis. COPYRIGHT: (C)2008,JPO&INPIT |
