Patent ID: 7660552
Filing Date: 2010-02-09
Classification: G03G

Abstract:
1. An image forming apparatus comprising: a conveying unit that conveys a transferred medium in a first direction; an image forming unit that forms an image on the transferred medium conveyed by the conveying unit; a controller that controls the image forming unit to form a test pattern on either one of the conveying unit and the transferred medium, the test pattern including first and second line segments slanting toward directions opposite to each other, wherein the first line segment is offset, in an offset direction, from a second direction orthogonal to the first direction and the second line segment is offset, in a direction opposite to the offset direction, from the second direction, the first and second line segments being offset from the second direction at equal angles; a detection unit that is disposed downstream from the image forming unit in the first direction and detects passage of at least respective parts of the first and second line segments; and a calculating unit that calculates a position where the image forming unit forms an image based on a time difference between times at which the detection unit detects the passage of the at least respective parts of the first and second line segments, wherein the first and second line segments are formed into step-like shapes, the first line segment extending by a plurality of dots in the second direction while extending by one dot in the first direction, and the second line segment extending by a plurality of dots in the second direction while extending by one dot in a direction opposite to the first direction, and wherein positions where the first and second line segments extend in the second direction are respectively shifted from each other in the second direction.