Patent ID: 9141060
Filing Date: 2015-09-22
Classification: G03G

Abstract:
1. An image forming apparatus comprising: a conveying unit configured to convey a sheet; an image forming unit configured to form a measurement image on a sheet along a main scanning direction orthogonal to a sheet conveying direction of the conveying unit; a fixing unit configured to fix the measurement image formed by the image forming unit onto the sheet by heating; a measuring unit configured to irradiate light to the measurement image on the sheet having passed through the fixing unit, measuring reflected light from the measurement image, and outputting a measured value; a discharging unit configured to discharge a sheet measured by the measuring unit; a feeding unit configured to rotate the direction of a sheet discharged by the discharging unit once such that the measurement image formed along the main scanning direction is along the sheet conveying direction; a first calculation unit configured to cause the measuring unit to output a measured value at a predetermined point of measurement on the measurement image after the sheet passes through the fixing unit, cause the feeding unit to feed the sheet, causing the sheet to pass through the fixing unit again, cause the measuring unit to output measured values at a plurality of points of measurement including the measured value at the point of measurement, and calculate a first correction coefficient from a first measured value and a second measured value at the point of measurement; a correction unit configured to correct the measured values at the plurality of points of measurement by using the first correction coefficient calculated by the first calculation unit; and a second calculation unit configured to calculate a second correction coefficient for correcting an unevenness in the main scanning direction on basis of the measured value at the plurality of points of measurement corrected by the correction unit.