Patent ID: 7852540

Claim:
An optical scanning apparatus comprising: a plurality of light source units; a common optical deflector configured to deflectively scan a plurality of light fluxes emitted from the plurality of light source units; and a first imaging optical system and a second imaging optical system arranged, within a main scanning section, to face each other across an optical axis direction and to sandwich the common optical deflector, the first imaging optical system and the second imaging optical system being configured to image, on different surfaces to be scanned, the plurality of light fluxes deflected and scanned by a deflection surface of the common optical deflector, the first imaging optical system and the second imaging optical system each having a respective resin imaging optical element, wherein: when the resin imaging optical element of the first imaging optical system, closest to the common optical deflector in an optical axis direction of the first imaging optical systems is set as a first imaging optical element, and the resin imaging optical element of the second imaging optical system, closest to the common optical deflector in an optical axis direction of the second imaging optical systems is set as a second imaging optical element, the first imaging optical element comprises a first standard positioning portion for positioning the first imaging optical element in a main scanning direction, the first standard positioning portion being disposed to be displaced from an optical axis of the first imaging optical system toward an image writing start side in the main scanning direction; and the second imaging optical element comprises a second standard positioning portion for positioning the second imaging optical element in a main scanning direction, the second positioning portion being disposed to be displaced from an optical axis of the second imaging optical element toward an image writing start side in the main scanning direction, and the following condition expression is satisfied: 0.02 ×YEA<|YP|< 0.30 ×YEA where YEA denotes one of a length of an entire effective portion of the first imaging optical element in the main scanning direction and a length of an entire effective portion of the second imaging optical element in the main scanning direction, and YP denotes one of a distance from the optical axis of the first imaging optical system to the first standard positioning portion in the main scanning direction and a distance from the optical axis of the second imaging optical system to the second standard positioning portion in the main scanning direction.