Patent ID: 8503035

Claim:
An image forming apparatus comprising: an image data generating unit configured to convert a tone of an input value which indicates a density of a pixel by using a predetermined dither matrix and generate image data; a scanning unit configured to scan an image carrier in a primary scanning direction according to the image data generated by the image data generating unit; an image forming unit configured to form, on a printing medium, an image corresponding to the image data scanned by the scanning unit; a drive source; and a gear configured to transmit a drive force from the drive source to the image carrier, wherein the dither matrix includes a plurality of sub-matrixes arranged in a predetermined rule and each of the plurality of sub-matrix having predetermined threshold values such that a dot in each of the plurality of the sub-matrixes grows from a corresponding original point, wherein the image forming apparatus satisfies a relation of (1) a≧0.08 mm and b/a<0.80, or (2) a<0.08 mm and b/a>1.27 where “a” is a travel distance of a printing medium per tooth of the gear in a secondary scanning direction orthogonal to the primary scanning direction, and “b” is a distance between the corresponding original points of a pair of the dots formed on the printing medium apart from each other in the secondary scanning direction on the basis of a pair of the sub-matrixes adjacent to each other in the primary scanning direction in the dither matrix.