| 摘要 |
PROBLEM TO BE SOLVED: To surely protect a circuit of a device in which constant electrical energy control of a lamp is performed, by surely deciding a state of matter even when bridge short-circuit of mercury occurs. SOLUTION: A projector has a lamp driving circuit 4 which drives the lamp 1, the lamp driving circuit 4 has a shunt resistor R which detects a lamp driving current I, and the lamp driving current I is PWM-controlled so that constant electrical energy driving of the lamp 1 is performed based on the lamp driving current I detected with the shunt resistor R. The control unit 8 has a lamp short-circuit decision function detector capable of detecting output signal levels of a smoothing circuit 7 which smoothes PWM control signals of the lamp 1 multiple times after a predetermined amount of time passes since the power source is switched on, and deciding a lamp short-circuit when the respective detected output signal levels are a certain level or less. COPYRIGHT: (C)2008,JPO&INPIT |
