Belt conveyance unit and an image formation apparatus

Abstract

A belt conveyor apparatus and an image formation apparatus therewith are disclosed. The belt conveyor apparatus includes a conveyance belt installed between a driving roller and a follower roller, the conveyance belt being rotationally movable. The position of the conveyance belt in the roller axle direction is regulated by a bead attached to the conveyance belt, and an edge or a slot provided on the driving roller. When the conveyance belt is rotationally moving, the follower roller can move in the thrust direction of the follower roller. The movable amount of the follower roller is made less than the clearance between the bead and the follower roller.

1 . A belt conveyance unit including a conveyance belt that is installed between a driving roller and a follower roller such that the conveyance belt is rotationally movable, wherein a position of the conveyance belt in directions of axles of the rollers is regulated by a bead attached to an inner surface of the conveyance belt for regulating slippage and the position of the conveyance belt, and one of a slot in the driving roller that meshes with the bead and an edge of the driving roller, the belt conveyance unit comprising: 
 a follower roller provided on an upstream side with reference to the driving roller in a belt conveyance direction such that the follower roller can move in a thrust direction of the follower roller, while the conveyance belt is rotationally moving; wherein    an amount of the movement of the follower roller in the thrust direction is set equal to or less than clearance between the bead of the conveyance belt and the follower roller.    
   
   
       2 . The belt conveyance unit as claimed in  claim 1 , further comprising: 
 a roller supporting member for supporting the follower roller such that the follower roller can rotationally move;    wherein the roller supporting member is installed such that the roller supporting member can move in a direction that reduces torsion between axles of the driving roller and the follower roller according to an amount of one of slippage magnitude and slippage force of the follower roller.    
   
   
       3 . The belt conveyance unit as claimed in  claim 2 , wherein the belt conveyance unit is structured such that the slippage force of the follower roller is directly or indirectly transmitted to the roller supporting member.  
   
   
       4 . The belt conveyance unit as claimed in  claim 2 , further comprising: 
 a supporting member that supports the roller supporting member such that the roller supporting member is movable;    wherein the roller supporting member and the supporting member have first inclined planes that are mutually parallel, but that are not parallel to the axle directions of the follower roller such that when the roller supporting member moves in the axle directions of the follower roller, the roller supporting member also moves in the direction perpendicular to the axle directions of the follower roller along the first inclined plane of the supporting member.    
   
   
       5 . The belt conveyance unit as claimed in  claim 4 , further comprising: 
 an energizing member that urges the roller supporting member toward the first inclined plane of the supporting member.    
   
   
       6 . The belt conveyance unit as claimed in  claim 4 , wherein the roller supporting member has a second inclined plane on a side opposite to the side of the first inclined plane.  
   
   
       7 . The belt conveyance unit as claimed in  claim 6 , further comprising: 
 a contact member that is attached to the axle of the follower roller outside of the roller supporting member, the contact member contacting the roller supporting member when the follower roller moves in a direction in which the follower roller is separated from the roller supporting member.    
   
   
       8 . An image formation apparatus that forms an image on a recording medium by an image formation unit while conveying the recording medium,  
     comprising: 
 the belt conveyance unit as claimed in  claim 1.