Patent ID: 6121732
Filing Date: 2000-09-19
Classification: H05B,Y10S

Abstract:
A power supply for a gas-discharge lamp, the power supply comprising:a voltage apparatus for producing a voltage having an asymmetrical voltage waveform, the voltage apparatus including a voltage source, a half-bridge inverter, and a timer;a transformer for stepping up the voltage from the voltage apparatus; anda blocking capacitor connected in series with the transformer and the lamp for preventing a DC current from flowing through the transformer and the lamp so that a DC voltage is established across the lamp without a DC current through the lamp, whereinthe half-bridge inverter is operatively connected to the voltage source and the transformer and periodically inverts a polarity of an output voltage from the voltage source, andthe timer is connected to the inverter and outputs a timing signal to control the inverting performed by the half-bridge inverter, whereinthe voltage apparatus includes a drive circuit connected to the timer and the half-bridge inverter for generating the voltage having the asymmetrical voltage waveform fed to the transformer, andthe drive circuit includes first and second switches respectively connected to first and second transistors of the half-bridge inverter, each of the first and second switches for switching between respective first and second drive voltages having respective first and second asymmetrical voltages waveforms based on the timing signal output from the timer, wherein the first asymmetrical voltage waveform for each of the first and second switches is inverted in polarity relative to the second asymmetrical voltage waveform for each of the first and second switches.