Patent ID: 7077530

Claim:
A projector of external power supply, the projector comprising: a DC power supply port, providing for receiving a DC voltage from the outside of said projector; a step-up circuit, including: an inductance, of which one end is connected to said DC power supply; a field effect transistor; a diode, of which one end is connected to said inductance and said field effect transistor; and a capacitance, of which one end is connected to said diode, and of which another end is grounded; a voltage regulation circuit; a lamp; and an igniter; said step-up circuit converts the DC voltage to a first electric potential, said first electric potential may actuate said igniter to light up said lamp and, after said lamp is lighted up, said step-up circuit regulates the working voltage of said lamp to a second potential voltage, said first electric potential being higher than said second electric potential; wherein when the projector is actuated, said DC voltage charges said inductance and said capacitance; after the voltage over said capacitance is equal to said first voltage, said igniter is actuated to generate a transient high voltage to light up said lamp.