JPS55138753A - Optical system driving control unit - Google Patents

Abstract

PURPOSE:To drive the optical system stably without using any return switch by controlling the backward movement start of the optical system when the count value of the specified number of pulses after the optical system moving speed becomes constant reaches the quantity corresponding to the size of transfer paper. CONSTITUTION:When the optical system drive signal causes a control circuit 28 to set an FF30, an AND gate 35 is opened by the high level output of the FF30 and at the same time a clutch is coupled, causing the optical system to make approach run. When the stable constant speed is reached, exposure is started by way of the optical sensor provided in the specified position. The reset of a counter 29 is released by the detection signal of this optical sensor and the pulses from a pulse generator 27 synchronized to the main motor 2 are counted by the counter 29. The count value of this counter 29 is compared with the pulse number which is set in the pulse setting circuit 36 corresponding to the size detection of transfer paper and when they coincide, the counter 29 is reset by the FF32 which is reset by a coincidence circuit 37, thus the backward movement of the optical system is stably started without using any return switch.