Patent ID: 8855514
Filing Date: 2014-10-07
Classification: G03G

Abstract:
1. An apparatus comprising: a rotatable belt; a first image bearing member configured to bear an electrostatic latent image, which is to be developed into a toner image; a second image bearing member, provided at a position downstream of said first image bearing member with respect to the rotational moving direction of said belt, configured to bear an electrostatic latent image, which is to be developed into a toner image; a first detecting member provided adjacent said second image bearing member with respect to the rotational moving direction of said belt and configured to detect a position of said belt with respect to a widthwise direction; a second detecting member provided adjacent said first image bearing member with respect to the rotational moving direction of said belt and configured to detect a position of said belt with respect to the widthwise direction; a steering roller configured to stretch said belt and configured to movably control the position of said belt with respect to the widthwise direction by inclination thereof; a first stretching roller, disposed at a position adjacent said steering roller, configured to stretch at one end portion of an image formation region of said belt along which said image bearing members are arranged; a second stretching roller, disposed adjacent said steering roller on an opposite side from said first stretching roller with respect to said steering roller, configured to stretch said belt, wherein a first distance between rotational axes of said steering roller and said first stretching roller measured along a plane perpendicular to the rotational axis of said steering roller is different from a second distance between rotational axes of said steering roller and said second stretching roller measured along the plane; an executing portion configured to execute an operation in a correction mode for determining timing at which formation of the electrostatic latent image starts on at least one of said first and second image bearing members with respect to the widthwise direction of said belt, which is crossing with a rotational direction of said belt, on the basis of a positional relation, with respect to the widthwise direction, between test toner images transferred onto said belt from said first and second image bearing members; a calculating portion configured to calculate a movement distance of a predetermined point on said belt with respect to the widthwise direction from a position of said second detecting member to a position of said first detecting member in the rotational moving direction; and an adjusting portion configured to adjust the timing determined by said executing portion, on the basis of a result of the calculation of said calculating portion in an operation of the correction mode and a result of the calculation of said calculating portion when the image is to be formed in accordance with an image formation signal.