| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of maintaining lighting of the discharge lamp even at power failure. <P>SOLUTION: When a voltage of a direct current power source E drops below a prescribed value, and it is decided as the power failure by a control means 16 functioning as an input voltage detection means, an on-off operation interval of a switching element SW1 making a smoothing capacitor C1 discharge is shortened, and a duty ratio is made asymmetrical by extending the on-off operation interval of a switching element SW2 making a smoothing capacitor C2 having a larger capacity than that of the smoothing capacitor SW1 discharge. The power to a high-pressure discharge lamp L from the smoothing capacitor SW2 is made larger than that from the smoothing capacitor SW1. Since the capacity of the smoothing capacitor SW2 is larger than that of the smoothing capacitor SW1, the lamp current of the high pressure discharge lamp L can be maintained for a relatively long period at power failure. At an instantaneous power failure, fade-out of the lamp can be prevented since the lamp current of the high-pressure discharge lamp L can be maintained. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
