Optical scanning device and image forming apparatus

An optical scanning device which deflects one or a plurality of light flux(es) originating from a light source by an optical deflecting unit, gathers the deflected light flux(es) to cause it (them) to form a beam spot(s) on a surface to be scanned by a scanning and image-forming optical system, and, thus, performs optical scanning of said surface to be scanned,

• wherein:
• said scanning and image-forming optical system includes one or a plurality of optical component(s) including a lens(es);
• at least one surface of a lens included in said scanning and image-forming optical system is a sub-non-arc surface having an arc or non-arc shape in a main scanning plane, and a non-arc shape in a sub-scanning plane;
• and
• the sub-non-arc surface has no rotational axis and is formed in the lens having a largest effective diameter in the main scanning plane.

An optical scanning device which deflects one or a plurality of light flux(es) originating from a light source by an optical deflecting unit, gathers the deflected light flux(es) to cause it (them) to form a beam spot(s) on a surface to be scanned by a scanning and image-forming optical system, and, thus, performs optical scanning of said surface to be scanned,

• wherein:
• said scanning and image-forming optical system includes one or a plurality of optical component(s) including a lens(es);
• at least one surface of a lens included in said scanning and image-forming optical system is a sub-non-arc surface having an arc or non-arc shape in a main scanning plane, and a non-arc shape in a sub-scanning plane;
• and
• the sub-non-arc surface has no rotational axis and is formed in the lens of said scanning and image-forming optical system, which lens has a surface in which, throughout an effective range of said lens, an incidence angle of a chief ray of the defected light flux incident on respective surfaces of said lens is equal to or smaller than 25 degrees.

An optical scanning device which deflects one or a plurality of light flux(es) originating from a light source by an optical deflecting unit, gathers the deflected light flux(es) to cause it(them) to form a beam spot(s) on a surface to be scanned by a scanning and image-forming optical system, and, thus, performs optical scanning of said surface to be scanned,

• wherein:
• said scanning and image-forming optical system includes one or a plurality of optical component(s) including a lens(es);
• at least one surface of a lens included in said scanning and image-forming optical system is a sub-non-arc surface having an arc or non-arc shape in a main scanning plane, and a non-arc shape in a sub-scanning plane;
• and
• the sub-non-arc surface expressed by a coordinate X(Y, Z) in an optical-axis direction is expressed by the following equation:
• X(Y, Z)=CmY2/[1+{square root over ({1−+L (1+K+L )Cm2Y2+L })}]+ΣAnYn
• +Cs(Y)Z2/[1+{square root over ({1−+L (1+Kz+L (Y+L ))Cs2+L (Y+L )Z2+L })}]+fSAG(Y, Z) (1)
• where ‘Y’ denotes a coordinate in a main scanning direction, ‘Z’ denotes a coordinate in a sub-scanning direction, ‘Cm’ denotes a paraxial curvature in the main scanning directions on the optical axis or in the vicinity thereof, ‘Cs(0)’ denotes a paraxial curvature in the sub-scanning directions on the optical axis or in the vicinity thereof, ‘Cs(Y)’ denotes a curvature in the sub-scanning plane at a coordinate Y in the main scanning direction, ‘K’ denotes a conical constant of a quadric curve in the main scanning plane on the optical axis, ‘Kz(Y)’ denotes a conical constant of quadric curve in the sub-scanning plane at a coordinate Y in the main scanning direction, and ‘fSAG(Y, Z)’ denotes a non-spherical-surface high-order correction amount.