| 20090302772 | FLUORESCENT LAMP DIMMING CIRCUIT - In one embodiment, a fluorescent lamp dimming circuit includes power factor correction control, dimming control, and switching devices. The power factor correction control may be connected to power factor correction circuitry that produces a regulated DC buss. The dimming control circuit may be connected to the input of the fluorescent lamp dimming circuit for producing a driver signal whose frequency varies depending on the input voltage waveform perhaps as modified by a dimmer. The control circuit may produce a drive signal with a duty cycle profile to drive switching devices. The switching devices invert the DC buss voltage to an AC voltage waveform for driving a resonant tank circuit. The resonant tank circuit may include an inductance, a capacitance, and the impedance of a fluorescent lamp. The AC voltage waveform when applied to the resonant tank circuit may cause the fluorescent lamp to dim based on the dimmer setting. | 12-10-2009 |
