Optical scanning apparatus and image forming apparatus using the same including relationship between interval between deflector and scanned surface and a natural convergent point

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a main scanning cross sectional diagram showing an optical scanning apparatus according to Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram showing θ1, θ2, and θ3 according to Embodiment 1 of the present invention;

FIG. 3 is a graph showing a relationship between θ1 and θ3 in a conventional optical scanning apparatus.

FIG. 4 is a graph showing a correlation between θ1 and θ3 according to Embodiment 1 of the present invention.

FIG. 5 is a graph showing a correlation between θ2 and θ3 according to Embodiment 1 of the present invention.

FIG. 6 shows a thickness of a lens disposed closest to a surface to be scanned according to Embodiment 1 of the present invention.

FIG. 7 is a graph showing fθ performance according to Embodiment 1 of the present invention.

FIG. 8 is a graph showing a field curvature in a main scanning direction according to Embodiment 1 of the present invention.

FIG. 9 is a graph showing each aberration in the main scanning direction according to Embodiment 1 of the present invention.

FIG. 10 is a graph showing a correlation between |K×θ| and L×tan θ in a conventional optical scanning apparatus (Japanese Patent Application Laid-Open No. 2001-296491).

FIG. 11 is an explanatory diagram showing a relationship between |K×θ| and L×tan θ in the conventional optical scanning apparatus (Japanese Patent Application Laid-Open No. 2001-296491).

FIG. 12 is a graph showing a correlation between |K×θ| and L×tan θ according to Embodiment 1 of the present invention.

FIG. 13 is an explanatory diagram showing a relationship between |K×θ| and L×tan θ according to Embodiment 1 of the present invention.

FIG. 14 is a graph showing partial magnification in the main scanning direction according to Embodiment 1 of the present invention.

FIG. 15 is a sub-scanning cross sectional diagram showing an image forming apparatus according to an embodiment of the present invention.

FIG. 16 is a schematic diagram showing a principal part of a color image forming apparatus according to an embodiment of the present invention.

FIG. 17 is a graph showing a correlation between θ2 and θ3 in a conventional optical scanning apparatus (Japanese Patent Application Laid-Open No. 2000-267030).

FIG. 18 is a graph showing a correlation between |K×θ| and L×tan θ in the conventional optical scanning apparatus (Japanese Patent Application Laid-Open No. 2000-267030).