Patent ID: 9176456
Filing Date: 2015-11-03
Classification: G03G

Abstract:
1. An image forming unit comprising: a first process roller configured to form a nip with an object; a second process roller provided to be capable of forming a nip with the first process roller; a bush member including a first journal portion journaling the first process roller and a second journal portion journaling the second process roller with the first process roller rested on the second process roller; a shifting mechanism configured to move the bush member in a direction of abutment and separation in which the first process roller journaled by the first journal portion abuts against and separates from the object; and a drive mechanism configured to actuate the shifting mechanism depending upon an image forming operation, wherein the first journal portion and the second journal portion are juxtaposed in the direction of abutment and separation, the first journal portion includes an escape shaped portion allowing the first process roller to shift in the direction of abutment and separation within the first journal portion and is configured to, when the first process roller is free from nip with the object, journal the first process roller with play in the direction of abutment and separation provided by the escape shaped portion, the first journal portion is configured to, when the first process roller forms a nip with the object by the movement of the bush member actuated by the shifting mechanism, journal the first process roller so that the first process roller is pressed by the object to shift to a position within the first journal portion close to the second process roller, the shifting mechanism includes a support portion supporting the bush member, a biasing member urging the bush member toward the object in the direction of abutment and separation, and a guide portion provided laterally of the bush member contained in the support portion and configured to guide movement of the bush member in the direction of abutment and separation urged by the biasing member, the bush member includes an engagement portion extending toward a bottom portion of the support portion facing the bush member and the guide portion is provided with a receiving hole receiving the engagement portion and allowing the engagement portion to pass therethrough, the engagement portion projects beyond the guide portion to have different amounts of projection between when the first process roller is free from nip with the object and when the first process roller forms a nip with the object, the image forming unit further comprises a position restricting member movable in a direction perpendicular to the direction of abutment and separation between a locking position with respect to the engagement portion projecting beyond the guide portion when the first process roller is free from nip with the object and an unlocking position with respect to the engagement portion, and the drive mechanism is configured to move the position restricting member between the locking position and the unlocking position.