HORIZONTAL SHIFT CLOCK PULSE SELECTING CIRCUIT FOR DRIVING COLOR LIQUID CRYSTAL PANEL

摘要

PROBLEM TO BE SOLVED: To prevent occurrence of video deviation caused at a PAL thinning time by canceling the effect of a switching noise due to a horizontal shift clock on an oscillated frequency of a voltage-controlled oscillator. SOLUTION: A horizontal shift clock switch circuit 4 selects odd line shift clocks CPHO1 to CPHO3 from an odd number line horizontal shift clock generating circuit 2 and even line shift clocks CPHE1 to CPHE3 from an even number line horizontal shift clock generating circuit 3 and supplies the selected clocks to a color liquid crystal panel 11. The horizontal shift clock switch circuit 4 ordinarily selects the odd line shift clocks CPHO1 to CPHO3 and the even line shift clocks CPHE1 to CPHE3 in response to a line discrimination signal VCP33 and provides an output, and in the case of PAL thinning, the horizontal shift clock switch circuit 4 inverts the selection state of the shift clock just after starting the PAL thinning from the selection state just before the thinning start and again inverts the selecting state at a period a half the one horizontal scanning period. COPYRIGHT: (C)2004,JPO