Patent ID: 7876486

Claim:
An optical scanning apparatus comprising: 2n (where n≧1) light sources, each light source including m (where m≧1) light emitting units; a synchronization detecting unit that receives m×n light beams from the light sources, scans a scanning surface by the light beams emitted by 2n light sources, and determines a write timing for writing to the scanning surface, the light beams being substantially symmetrical with respect to a sub-scanning cross-section that includes a rotational axis of an optical deflector; a first scanning lens system and a second scanning lens system arranged on either side of the optical deflector and causing m light beams to perform imaging on the respective scanning surfaces, wherein synchronization detection by the synchronization detecting unit is performed at one end of each scan line, and the first scanning lens system and the second scanning lens system are arranged substantially symmetrically with reference to a line in a main scanning direction orthogonal to the rotational axis of the optical deflector, and the scanning lens system includes a no-power portion in the main scanning direction, and the light beams guided to the synchronization detecting unit pass through the no-power portion.