Patent ID: 8330993
Filing Date: 2012-12-11
Classification: H04N

Abstract:
1. 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 to 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 comprises a plurality of sub-matrixes arranged in a predetermined rule and each of the plurality of sub-matrixes having predetermined threshold values, such that a dot in each of the plurality of the sub-matrixes grows from a corresponding original point, the plurality of sub-matrixes comprises a first sub-matrix and a second sub-matrix that has a predetermined positional relation with the first sub-matrix, wherein the image forming apparatus satisfies a relation of: 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 component in the secondary scanning direction of a distance between the original point of the dot derived from the first sub-matrix and the original point of the dot derived from the second sub-matrix, and wherein the second sub-matrix is one of the sub-matrixes next to the first sub-matrix and is positioned, such that the distance b is greater than the distance b of the other sub-matrixes next to the first sub-matrix.