Patent ID: 8159513

Claim:
An image forming apparatus comprising: an image forming circuit having an image memory; a light beam generation unit arranged to generate a light beam controlled according to image data supplied by said image forming circuit; a light deflector arranged to deflect the light beam in a main scanning direction; a photosensitive member onto which the deflected light beam is irradiated, said photosensitive member being moved in a sub-scanning direction; and a driving control unit configured to drive said light deflector and control said light beam generation unit, wherein said driving control unit generates a frequency difference generation signal when a difference between a frequency of a driving signal to drive said light deflector and a resonance frequency of said light deflector exceeds a setting value, and a non-drawing time detection signal when a non-drawing area whose size exceeds a threshold value is detected in the image memory, and wherein, when both the frequency difference generation signal and the non-drawing time detection signal are generated, said driving control unit stops operation of said light beam generation unit according to image data, and changes the frequency of the driving signal to the resonance frequency of said light deflector.