Image forming apparatus

An image forming apparatus comprising:

• a photosensitive member rotatable in a first direction;
• an exposure portion including a plurality of surface light emitting element arrays arranged in a second direction substantially perpendicular to the first direction and configured to expose said photosensitive member to light by said surface light emitting element arrays;
• and
• a clock generating portion configured to generate a clock signal,
• wherein said clock generating portion generates a reference clock signal for controlling light emission timing and a spread spectrum modulation clock signal obtained by subjecting the reference clock signal to frequency modulation,
• wherein each of said surface light emitting element arrays includes a plurality of light emitting elements for exposing said photosensitive member to light,
• wherein said exposure portion exposes said photosensitive member to light by sequentially subjecting a predetermined number of said light emitting elements of each of said surface light emitting element arrays to light emission control on the basis of a signal obtained by subjecting the modulation clock signal to modulation with image data, and
• wherein a modulation cycle in which a frequency of the modulation clock signal is modulated is n times (n:
• integer of n>1) an exposure cycle which is a time in which said light emitting elements of each of said surface light emitting element arrays are subjected to the light emission control on the basis of the reference clock signal.