| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp lighting system for maintaining a stable peak value for a tube current even in the case of a great change in brightness due to burst light control. SOLUTION: In the discharge lamp lighting system, there are generated a first frequency PWM pulse corresponding to a brightness set value in synchronization with a vertically synchronous signal from a display image and a second frequency PWM pulse having a frequency higher than the frequency of the first PWM pulse, which are converted into a high voltage alternating current in accordance with the result of a logical product of the first frequency PWM pulse and the second frequency PWM pulse for driving a cold cathode ray tube. The peak value for a current flowing in the cathode ray tube is detected at a timing a preset time delayed from the first PWM pulse for setting the brightness and the duty ratio of the second PWM pulse is controlled in accordance with the detection result. COPYRIGHT: (C)2004,JPO |
