| 摘要 |
PROBLEM TO BE SOLVED: To provide a liquid crystal display panel driver in which an image display area is not reduced without losing display quality of a video image and increasing a peripheral circuit in the case that a video signal with an aspect ratio of 16:9 using a 3-phase clock pulse is displayed on a liquid crystal display panel whose aspect ratio is 4:3. SOLUTION: Delay circuits 4, 5 are provided to the output of a 1/4 frequency divider circuit 3 of original oscillation signal. Let a sampling pulse obtained via an interlocking changeover switch 6 selecting a 1/3 frequency division reference signalϕ1 or the output of the 1/4 frequency divider circuit 3 be CPH1, a sampling pulse obtained via an interlocking changeover switch 7 selecting a 1/3 frequency division reference signalϕ2 or a signal from a delay circuit 4 be CPH2, and a sampling pulse obtained via an interlocking changeover switch 8 selecting a 1/3 frequency division reference signalϕ3 or a signal of a delay circuit 5 be CPH3, then the sampling pulses CPH1-CPH3 form the usual video display mode when the switches 6, 7, 8 are thrown to the position of a 1/4 frequency division signal, and the sampling pulses CPH1-CPH3 form the transversal video image extension display mode when the switches 6, 7, 8 are thrown to the position of a 1/3 frequency division signal.
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