| 摘要 |
PURPOSE:To prevent errors from being generated even when a leading end protruding operation is repeated and prevent misregister of colors from occurring, by monitoring by a detector a leading end protruding position for a printing paper. CONSTITUTION:Since reflected light from a mark 21 is weaker than reflected light from the other part, an output obtained by detecting the former reflected light by a photo-transistor 221 and converting the detection signal into a voltage is lower than a reference voltage (c). The output is compared with the reference voltage (c) by a discriminating circuit 6, and since the voltage (c) is higher, a stopping command is generated in a motor-driving circuit 7. At this position, the number of steps in a pulse motor 8 is reset to zero, and a leading end protruding position is set. Thereafter, printing in the first color 3-a is conducted. After completion of the printing, the printing paper is rewound in the direction of an arrow (b) by a pin tractor 1 driven by a pulse motor or the like, in which case the position-detecting mark 21 of the paper 2 is detected by a sensor 22, whereby closed-loop control is conducted to set the paper to a predetermined leading and protruding position. |
