Patent ID: 6693396
Filing Date: 2004-02-17
Classification: H05B

Abstract:
An apparatus for driving a discharge lamp comprising:a switching regulator receiving a DC voltage source and producing a low voltage DC signal, having a switch configured to turn on and off periodically in response to a duty cycle of a dimming control signal to chop up the DC voltage source output, for regulating an average magnitude of the low voltage DC signal; level shifter circuitry for translating the dimming control signal to a voltage level required for turning on the switch; and a DC-to-AC inverter configured to step up the low voltage DC signal to a high voltage AC signal applied to the discharge lamp, in which the high voltage AC signal provides a lamp current flowing through the discharge lamp; wherein the duty cycle of the dimming control signal is varied according to a brightness table of the relationship between the duty cycle and the lamp current.