| 摘要 |
PURPOSE:To prevent a means of driving an original imposing plate in a forward direction by changing over the polarities of a power source and in response to the polarities changed and a means for driving the same in a backward direction from being exerted with undue forces and being broken by providing both driving means. CONSTITUTION:A scan clutch CLH3 operates when current of + is applied to one signal line (a) and a return clutch CLH4 operates when current of + is applied to the other signal line (b). Hereupon, to cause scanning, a switch SW3 is turned on, and at this time, a polarity control switch SW4 is set in a positive position. Then, the current passes the scan clutch CLH3 and the scanning is started. When the switch SW3 is turned off and the polarity control switch SW4 is turned on during this time and when the switch SW3 is turned on again after this, this time the current flows to the return clutch CLH4, by which the return is started. With such constitution, the simultaneous turning-on of both clutches does not occur any longer; hence, the exertion of undue stresses upon both driving means does not occur, and their breakage is prevented. |
