| 摘要 |
PURPOSE:To obtain a wide-band video without any cut-off of a video software in higher and lower positions by varying the vertical amplitude length, the distance from a vertical synchronizing pulse, and the horizontal amplitude of a video corresponding to the length of a detected blanking period. CONSTITUTION:A TV signal inputted from an input terminal 11 is converted by an A/D converter 12 with a clock from a clock generation circuit 13, and stored in line memories 17, 18. For the write clock W-CK and the read clock R-CK, same clocks are used in case of a video software for movie size picture, but in case of a software for normal size picture, the frequency of the W-CK is made higher than that of the R-CK. Data is written and read alternately in and from the memories 17, 18; a switching circuit 19 switches the memories 17, 18 with alternating pulses from a synchronizing separator circuit 14 to supply data to a delay circuit 23. The vertical-blanking-width difference is obtained from a vertical synchronizing pulse from the circuit 14 and an output from a detection circuit 16. A delay amount is determined corresponding to the resulting difference, and the video is displayed in a cathode-ray tube 22 after being subjected to a D/A converter 20.
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