Patent ID: 7873310
Filing Date: 2011-01-18
Classification: G03G

Abstract:
1. An oblique movement preventing device for an endless belt, the endless belt including an inner surface, an outer surface, and both side parts in a width direction of the belt, the inner surface being supported by a plurality of supporting rollers, at least one of the rollers being a driving roller applying a rotation force to the belt and circulating the belt on the rollers in a predetermined circulating direction, the oblique movement prevention device comprising: a contact angle changing unit which includes a press roller arranged along the outer surface of the belt and extending in the width direction at a position near to the driving roller in an upstream side of the driving roller in the predetermined circulating direction of the belt, and a swing source selectively swinging the press roller in a direction crossing the outer surface of the belt to make the press roller press either of the both side parts of the belt, thereby changing a contact angle of the belt on the driving roller along the width direction of the belt; a measuring unit which is configured to measure a direction and distance of displacement of the belt caused by an oblique movement of the belt; a control unit which is configured to control the operation of the swing source of the contact angle changing unit for the selective swinging of the press roller in the direction crossing the outer surface of the belt to make the press roller press either of the both side parts of the belt, and to cease the oblique movement of the belt, based on the measured direction and distance of displacement of the belt; and a warp canceling unit which includes a warp suppressing roller, and which is configured to make the warp suppressing roller press the inner surface of the belt with an elasticity at a position near to the press roller in an upstream side of the press roller in the predetermined circulating direction of the belt, thereby canceling a warp of the belt caused by the press of the press roller of the contact angle changing unit to either of the both side parts of the outer surface of the belt, so that a part of the belt in the upstream side of the driving roller between the warp suppressing roller and the driving roller keeps flat.