Patent ID: 7903134

Claim:
A laser scanning apparatus, comprising: a light source unit including a plurality of light emitters, the plurality of light emitters being two-dimensionally arranged; a controller configured to select a subset of at least three of the plurality of light emitters, but less than all of the plurality of light emitters, to generate detection light beams; a deflector for deflecting the detection light beams from the light source unit; a scanning optical system for condensing the detection light beams deflected by the deflector on a surface to be scanned; and a photo detector to which a the detection light beams, which are deflected by the deflector and pass through the scanning optical system, are incident while moving in a main scanning direction, and which includes at least one light-receiving device having a first light-receiving unit and a second light-receiving unit, the first light-receiving unit and the second light-receiving unit being placed in different intervals from each other in the main scanning direction depending on a position in a direction orthogonal to the main scanning direction in a light-receiving surface, wherein every size of the first and the second light-receiving units is a size covering an overall virtual area in a quadrangular shape surrounding a plurality of light spots arranged two-dimensionally in the light-receiving surface of the photo detector, the plurality of light spots being a plurality of spots of the detection light beams.