that section 5 indicates that the vertical scanning speed is too high in the automatic vertical scanning mode the output signal of detector 31 goes low then the output of and gate 43 causes motor driver 40 to be in operation under this condition if the document is set between image reader 1 and transmitter 2 the output of sensor 33 goes low and the output of inverter 45 goes high so that the output of nor gate 46 goes low accordingly the pulse signal from encoder 30 is input to the clock input ck of ff 56 through and gate 49 as a result the clock signal dck is generated as in the case of the manual vertical scanning to execute the storage of the image signal into memory 37 in the automatic vertical scanning mode the document is transferred at a fixed vertical scanning speed by motor 24 and hence the period of the pulse signal generated by encoder 30 is substantially equal to that of clock signal clk1 for this reason no error signal is generated although it is generated in the automatic vertical scanning mode the reading operation of the image reader 1 ends when the end of the document is detected by sensor 33 or the number n of horizontal.