| 摘要 |
PURPOSE:To obtain a normal print picture without black stripes and picture missing by changing a picture data fetch start position with respect to a horizontal synchronizing signal depending whether a synchronizing pulse width is larger than a prescribed value or smaller. CONSTITUTION:A counter 10 releases clear when a vertical synchronizing signal VSYNC descends, is brought into the enable state when the 1st horizontal synchronizing signal HSYNC rises and counts clock pulses CP while the horizontal synchronizing signal is at an H level. Thus, the width of the synchronizing pulse of the horizontal synchronizing signal is detected by a count of the counter 10. For example, 50 (dot number) is set to the counter 10 as a prescribed value and the signal is zero till the count of the clock pulse reaches 50 and a signal (a) is sent when the count exceeds 50 and the signal is latched by a latch circuit 11 until the succeeding vertical synchronizing signal VSYNC rises. A data select 12 selects its output value to 176-dot when the latch circuit 11 latches the signal (a) and selects the output value to 168-dot when the zero signal is latched. |
