Patent ID: 8477170

Claim:
An image forming apparatus comprising: a laser driver unit that makes an illumination element emit a laser beam according to an input image signal; a controller unit that controls said laser driver unit; and a plurality of signal lines that connect the laser driver unit and the controller unit to each other so that an image signal converted into a differential signal or a control signal converted into a differential signal is output from the controller unit to the laser driver unit via the plurality of signal lines, wherein said laser driver unit includes: a laser beam detector that detects a laser beam emitted from the illumination element; and a horizontal synchronization signal generator that generates a horizontal synchronization signal as a single-ended signal which is electrically transmitted to the controller unit via any one of the plurality of signal lines and used as a reference of an image writing timing in response to detection of the laser beam detector, wherein said one of the plurality of signal lines is a common signal line used for electrically transmitting a part of the converted image signal or the converted control signal and for electrically transmitting the horizontal synchronization signal as a single-ended signal.