To provide an image forming apparatus, a signal controlling method and a memory medium wherein a horizontal synchronizing signal and a vertical synchronizing signal are transmitted in a single signal line so that the number of synchronizing signals necessary for an image forming operation can be reduced and a load of an operation by a video controller can be reduced.
This image forming apparatus comprises the video controller 103 for executing an image processing, a TOP sensor 119 for detecting a top end of a paper sheet and an engine controller 105. The engine controller 105 performs the controlling wherein the horizontal synchronizing signal of image data in a first pulse width is transmitted to the video controller 103 in synchronism with a beam position pulse signal outputted from a waveform shaping circuit 20 and the controlling wherein the horizontal synchronizing signal is changed to one in a second pulse width to be outputted based on the detection of the top end of the paper sheet by the TOP sensor 119 and then the vertical synchronizing for start of the image data is transmitted to the video controller 103.
AKIYAMA SATORU
KISHIDA TETSUO
