Patent ID: 7643783
Filing Date: 2010-01-05
Classification: G03G

Abstract:
1. An image forming apparatus for forming an image on a sheet, comprising: an image carrier being driven by a driving source, configured to carry an image; an image reading unit configured to read the image upon the image carrier, wherein the image reading unit has a plurality of sensor elements arranged in two dimensions and the plurality of sensor elements are divided into multiple sensor element groups; a sampling unit configured to sample an output of each sensor element group of the multiple sensor element groups at each of plural sampling times, wherein the sensor element groups respectively have the same number of sensor elements arranged in two dimensions; a decision unit configured to decide first and second sensor element groups for respectively being sampled at first and second sampling times, wherein the first sampling time is followed by the second sampling time; a position detection unit configured to detect positions of a predetermined pattern included in an image output from the first sensor element group at the first sampling time and the predetermined pattern included in an image output from the second sensor element group at the second sampling time; and a computation configured to compute a moving speed of the image carrier based on a difference between the first sampling time and the second sampling time and the positions detected by the position detection unit, wherein the decision unit decides the second sensor element group based on an assumption speed of the image carrier and the difference between the first sampling time and the second sampling time.