| 摘要 |
PURPOSE:To reduce the number of pieces and the width of noise bars at the time of high-speed reproduction and to prevent the blurring of a picture by detecting a recording track width from the envelope detecting signal of a reproduced video signal, and smoothing the envelope waveform of a signal stored in a field memory based on the result of said detection. CONSTITUTION:The points differing from the conventional technic are that the output of an envelope detector 5 is supplied to a comparator 6 via a variable amplifier 13 and that a microcomputer(MC) 20 controlling the amplification ratio of the amplifier 13 is comprised. The MC 20 receives a synchronizing signal from a video signal processing circuit 4 and an output from the comparator 6, and outputs an optimum potential to determine the amplification ratio of the amplifier 13 to the amplifier 13 via a D/A converter 30. A table in which the optimum amplification ratios of the amplifier 13 against the widths of detected recording tracks are written, is comprised in the MC 20. Also, a detection means detecting the recording- track width is constituted by the MC 20 and the comparator 6, and a means making the amplification ratio of an envelope detecting signal optimum is constituted by the MC 20, the D/A converter 30, and the amplifier 13. By a control means consisting of such means, the comparator 6, and a memory control 7, reproduced video signals smoothly continued at the reference potential S for comparison are written to the field memory 8.
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