Patent ID: 7015656

Claim:
A dimming circuit of a gas-discharge lamp comprising: a first terminal and a second terminal for inputting AC power; a variable resistor, said variable resistor having a second end connected to said first input terminal; a capacitor, said capacitor having a first end connected to a first end of said variable resistor and a second end connected to said second input terminal; a bi-directional diode, said bi-directional diode having a first end connected to the first end of said variable resistor and the first end of said capacitor, and a second end; a TRIAC, said TRIAC having a gate thereof connected to the second end of said bi-directional diode, a first end connected to said second input terminal, and a second end; a switch connected to one of said first input terminal and said second input terminals for circuit on/off control, for enabling the light intensity of the gas-discharge lamp to be regulated subject to change of the resistance value of said variable resistor; a phase feedback control circuit, said phase feedback control circuit comprising a first inductance, said first inductance having a first end connected to said first input terminal and a second end, a second capacitor and a third capacitor connected in parallel between two opposite ends of said first inductance and the second end of said TRIAC, a second inductance, a fourth capacitor connected in parallel to said second inductance, said fourth capacitor having a first end connected to the second end of said first inductance and a second end, and a fifth capacitor connected to the second end of said fourth capacitor.