PURPOSE: To ensure the stable scan by using a control means which performs the average scan with a prescribed shift amount by driving a step motor of a scanner every integer steps and changing the number of said steps for every prescribed number of times.
CONSTITUTION: When an original is set, both switches 37 and 38 are operated. Then the size of the original is informed to a controller 11. Then a transmission line is set up and a start switch on a control panel 10 is operated. Thus a procedure signal is transferred to decide a transmission mode. A flag which decides the step amount is set at a low level at first and then switched in a fine reduction mode in response to the output of a counter which divides the paper feed signal of a step motor 7 into two parts. Thus the motor 7 is revolved by an amount equivalent to two or three steps of a 1.2 phase driving energizing system and every time the paper is fed by an amount equivalent to two lines.