| 摘要 |
PURPOSE:To freely vary the direction and the speed of scroll of a still picture only by operating a single scroll dial, by designating the direction of the scroll corresponding to the rotational diraction of a scroll dial, and designating scroll speed corresponding to as angle of rotation. CONSTITUTION:The frequency of a scroll speed variable clock pulse S5 supplied to the clock pulse input terminal CLK of a counter 100 is varied corresponding to the angle of rotation of the scroll dial. When the scroll dial is rotated in a clockwise direction, the counter 100 starts a count up operation, and when it is rotated in a counter-clockwise direction, the counter 100 starts a count down operation, and the still picture on a display screen is scrolled horizontally by eight bits at every increase/decrease of the value of the counter 100. Thus, it is possible to vary freely both the scroll direction and the scroll speed of the still picture on the display screen only by operating the single scroll dial.
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