| 摘要 |
PURPOSE:To keep the amount of winding constant by a method in which the feeding speed of a thermal ink ribbon is detected on the basis of the output of a photo sensor to detect the density of the thermal ink ribbon, and the turning speed of a motor is controlled in such a way as to make the feeding speed constant. CONSTITUTION:When the banded discriminators 15 and 17 of a thermal ink ribbon 14 are matched with a photo sensor 12, command signal So of fixed pulse width To is sent out from an arithmetic unit 20, and the step number of the step motor 9 is counted by a counter 19. When the colorant portion of the ribbon 14 comes to match with the sensor 12, maximum value of counted contents of the counter 19 is stored, and command signal So' of a pulse width DELTAT corresponding to the stored value is sent out. As the pulse width DELTAT is increased, the turning speed of the motor 9 is slowed down. The pulse width DELTAT is sent up to be increased with increasing the winding diameter of the ribbon 14 on the winding shaft. |
