Optical scanning device and image forming apparatus

An optical scanning device, comprising:

• a first light source and a second light source;
• a deflector configured to deflect a first light beam and a second light beam respectively emitted from the first light source and the second light source;
• a first imaging optical element configured to give predetermined properties to the first light beam and the second light beam deflected by the deflector;
• a second imaging optical element configured to guide the first light beam emitted from the first imaging optical element onto a first surface to be scanned;
• and
• a third imaging optical element configured to guide the second light beam emitted from the first imaging optical element onto a second surface to be scanned, wherein:
• the first light beam and the second light beam emitted from the first light source and the second light source have an opening angle between principal rays of the first light beam and the second light beam in a main scanning direction, and are incident on a same surface of the deflector at different positions deviating from each other in a deflecting axis direction while orthogonal to a deflecting axis of the deflector,
• the deflector is configured such that the principal rays of the deflected first light beam and the deflected second light beam are incident on the first imaging optical element while separated from an optical axis of the first imaging optical element at a predetermined distance,
• the first light source and the second light source are shifted relative to each other in a direction parallel to a rotation axis of the deflector, and
• the first imaging optical element gives positive optical power in a sub-scanning direction to the incident first light beam and second light beam over a main scanning direction, and a focal position respectively exists between the first imaging optical element and the second imaging optical element and between the first imaging optical element and the third imaging optical element.

An image forming apparatus, comprising:

• an optical scanning device;
• and
• an image recording section configured to form an image on an image receiving medium using light beams emitted from the optical scanning device, wherein
• the optical scanning device comprises:
• a first light source and a second light source;
• a deflector configured to deflect a first light beam and a second light beam respectively emitted from the first light source and the second light source, wherein the first light source and the second light source are shifted relative to each other in a direction parallel to a rotation axis of the deflector;
• a first imaging optical element configured to give predetermined properties to the first light beam and the second light beam deflected by the deflector;
• a second imaging optical element configured to guide the first light beam emitted from the first imaging optical element onto a first surface to be scanned;
• and
• a third imaging optical element configured to guide the second light beam emitted from the first imaging optical element onto a second surface to be scanned,
• wherein:
• the first light beam and the second light beam emitted from the first light source and the second light source have an opening angle between principal rays of the first light beam and the second light beam in a main scanning direction, and are incident on a same surface of the deflector at different positions deviating from each other in a deflecting axis direction while orthogonal to a deflecting axis of the deflector,
• the deflector is configured such that the principal rays of the deflected first light beam and the deflected second light beam are incident on the first imaging optical element while separated from an optical axis of the first imaging optical element at a predetermined distance, and
• the first imaging optical element gives positive power to optical power in a sub-scanning direction to the incident first light beam and second light beam over an entire main scanning direction, and a focal position respectively exists between the first imaging optical element and the second imaging optical element and between the first imaging optical element and the third imaging optical element.