Optical scanning apparatus and image forming apparatus using the same

An optical scanning apparatus for scanning a plurality of surfaces to be scanned, comprising:

• a plurality of light sources;
• an optical deflector for deflecting and reflecting a plurality of light beams emitted from the plurality of light sources;
• and
• an imaging optical system for guiding the plurality of light beams which are deflected and reflected by the optical deflector to the different surfaces to be scanned,
• wherein:
• the plurality of light beams incident on the optical deflector are incident on a deflection surface of the optical deflector at different angles to a normal of the deflection surface within a sub scanning section;
• the imaging optical system comprises a first optical element;
• the first optical element is commonly used for the plurality of light beams;
• and
• optical power of the first optical element satisfies 0≦|φ1s|<0.001 where φ1s represents optical power of the first optical element within the sub scanning section,
• the imaging optical system further comprises a plurality of second optical elements respectively provided for the plurality of light beams, and each of the plurality of second optical elements has optical power in a sub scanning direction, such that optical power of the first optical element and optical power of each of the plurality of second optical elements within a main scanning section are represented by φ1m and φ2m, respectively, and satisfy |φ1m/φ2m|>2.0, and
• each of the plurality of second optical elements has a shape in which at least one of a light incident surface and a light exit surface has no inflection point within a main scanning section;
• and
• optical power on the off-axis of each second optical element is lower than optical power on the on-axis of each second optical element within the sub scanning section.

An optical scanning apparatus for scanning a plurality of surfaces to be scanned, comprising:

• a plurality of light sources;
• an optical deflector for deflecting and reflecting a plurality of light beams emitted from the plurality of light sources;
• and
• an imaging optical system for guiding the plurality of light beams which are deflected and reflected by the optical deflector to the different surfaces to be scanned,
• wherein:
• the plurality of light beams incident on the optical deflector are incident on a deflection surface of the optical deflector at different angles to a normal of the deflection surface within a sub scanning section;
• the imaging optical system comprises a first optical element and a plurality of second optical elements respectively provided for the plurality of light beams;
• the first optical element is commonly used for the plurality of light beams;
• and
• optical power of the first optical element satisfies 0≦|φ1s|<0.001 where φ1s represents optical power of the first optical element within the sub scanning section,
• wherein a magnification of the imaging optical system within the sub scanning section is 1.3-fold magnification or less;
• and
• the plurality of light beams are divided after transmitted through the first optical element and each of the divided light beams is incident on a respective one of said plurality of second optical elements.

An optical scanning apparatus for scanning a plurality of surfaces to be scanned, comprising:

• a plurality of light sources;
• an optical deflector for deflecting and reflecting a plurality of light beams emitted from the plurality of light sources;
• and
• an imaging optical system for guiding the plurality of light beams which are deflected and reflected by the optical deflector to the different surfaces to be scanned,
• wherein:
• the plurality of light beams incident on the optical deflector are incident on a deflection surface of the optical deflector at different angles to a normal of the deflection surface within a sub scanning section;
• the imaging optical system comprises a first optical element;
• wherein said optical scanning apparatus further comprises;
• an optical member which is movable and/or deformable on an optical path;
• and
• an adjustment member for adjusting a curvature of a scanning line on the surface to be scanned;
• the first optical element is commonly used for the plurality of light beams;
• and
• optical power of the first optical element satisfies 0≦|φ1s|<0.001 where φ1s represents optical power of the first optical element within the sub scanning section.