Patent ID: 6899434

Claim:
A projector comprising: an image display device which displays an image; a projection section which illuminates the image display device with a light source lamp to project reflected light or transmitted light from the image display device onto a screen, thereby projecting the image displayed on the image display device onto the screen; a rectifying circuit which full-wave rectifies an AC power supply input to a main unit; a power-factor improving circuit which improves a power factor of an output of the rectifying circuit; a lamp power supplying circuit to which a DC output of the power-factor improving circuit is supplied as an input power supply, and which supplies a power to the light source lamp; a driver circuit which operates the lamp power supplying circuit; and a DC—DC converting circuit which uses a transformer to covert the DC output of the power-factor improving circuit to a DC current of a predetermined voltage, and which supplies the DC current to a secondary side; wherein an auxiliary winding is disposed in a primary side of the transformer of the DC—DC converting circuit; the power-factor improving circuit is a circuit which has a switching transistor and a control IC for controlling the switching transistor, and in which a voltage appearing in the auxiliary winding is used as a power supply for operating the control IC; and when the voltage appearing in the auxiliary winding is lower than a preset voltage, the driver circuit sets the lamp power supplying circuit to a stop a state.