Patent ID: 8521046
Filing Date: 2013-08-27
Classification: G03G

Abstract:
1. An image forming apparatus comprising: a first image carrier; a first image forming unit which forms an image on the first image carrier; an intermediate transfer body to which the image formed on the first image carrier is primarily transferred; a primary transfer unit which primarily transfers the image from the first image carrier to the intermediate transfer body; a secondary transfer unit which secondarily transfers the image transferred to the intermediate transfer body to a recording medium; a second image carrier which is disposed at upstream or downstream in a transport direction of the recording medium from a secondary transfer position where the image is secondarily transferred from the intermediate transfer body to the recording medium; a second image forming unit which forms an image on the second image carrier; a direct transfer unit which directly transfers the image formed on the second image carrier to the recording medium; a recording medium transport belt which is rotatably suspended by a plurality of roller members to transport the recording medium mounted thereon so as to pass a direct transfer position where the image is directly transferred from the second image carrier to the recording medium and the secondary transfer position; and a pattern image sensing unit which is disposed to face a front surface of the recording medium transport belt and which senses a pattern image transferred to the recording medium transport belt after being formed on the first image carrier and the second image carrier, wherein a distance between the secondary transfer position and the sensing position of the pattern image by the pattern image sensing unit in a rotation direction of the recording medium transport belt and a distance between the direct transfer position and the sensing position in the rotation direction of the recording medium transport belt are a natural number times a circumferential length of a roller member causing a speed change in the recording medium transport belt among the plurality of roller members by which the recording medium transport belt is suspended, and wherein when a radius of a driven roller which is driven to rotate by the rotation of the recording medium transport belt among the plurality of roller members by which the recording medium transport belt is suspended is denoted by r