| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of flickers and interference fringes on a display when the frequencies of a vertical synchronizing signal and horizontal synchronizing signal of a video input signal of a liquid crystal display device are changed. SOLUTION: A frequency detection circuit 25 sets the frequency of a driving pulse voltage z near (integer + 1/2) times as large as the frequency of the horizontal synchronizing signal c, sets the frequency of QWM control lighting near integer times or near (integer + 1/2) times as large as the vertical synchronizing signal d and sets a resonance frequency near the frequency of a driving pulse voltage z by regulating the the capacity value of a resonance capacitor 31. Even if, therefore, there is a change in the frequencies of the horizontal synchronizing signal c and the vertical synchronizing signal d, the visual recognition of the flickers and ripples due to the interference of the driving pulse voltage z of a discharge tube 32 and the horizontal synchronizing signal c thereof on a liquid crystal panel 21 is suppressed and the degradation in the efficiency of the discharge tube 32 is prevented. COPYRIGHT: (C)2006,JPO&NCIPI |
