| 摘要 |
PROBLEM TO BE SOLVED: To provide a liquid crystal display device properly displaying an unknown image signal. SOLUTION: Synchronization signals of an input video signal are supplied to a micro computer 13 through a synchronizing signal processing part 12 to detect individual frequencies of horizontal and vertical synchronizing signals and the polarities of synchronizing signals, to check against specification information of video signals registered in a ROM, and to determine the type of the input video signal. When the determination is successful, further specification information such as a dot clock is read out. Otherwise, the number of vertical lines is obtained from the synchronizing signals, and the number multiplied by 1.7 is considered as a dot clock to calculate specification information with GTF. Based on the obtained specification information, a PLL circuit 15 and a video signal converting device 17 are controlled. The input video signal is amplified by an amplifier 11, is converted into a digital signal after a proper sampling in an A/D converter 16, is converted into a signal proper for display on a liquid crystal display panel 18 by a video signal converting device 17 to impress on the liquid crystal panel 18.
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