Image heating apparatus using flexible sleeve

Abstract

An image heating apparatus includes a flexible sleeve, a sliding member for sliding on the inner periphery of the sleeve, and a back-up member for forming a nip portion together with the sliding member through the sleeve. A recording material for bearing an image is heated while being held and conveyed by the nip portion, and a regulation member is set by facing the edge surface of the sleeve in the generatrix direction to regulate the movement of the sleeve in the generatrix direction, the regulation member having a regulation surface with which the edge surface of the sleeve contacts when the sleeve moves in the generatrix direction. The regulation surface of the regulation member has a curved-surface area in which a line when the regulation surface is cut at a virtual plane almost parallel with the nip portion is a curved line expanded toward the edge surface of the sleeve. Thereby, an image heating apparatus is provided which is able to restrain deterioration of the durability of the flexible sleeve.

What is claimed is: 
     
       1. An image heating apparatus comprising:
 a flexible sleeve; 
 a sliding member for sliding on an inner periphery of said flexible sleeve; 
 a back-up member for forming a nip portion together with said sliding member through said flexible sleeve; wherein a recording material for bearing an image is heated while being held and conveyed in a moving direction of the recording material by the nip portion; and 
 a regulation member provided opposing the an edge surface of said sleeve in a generatrix direction of said sleeve, for regulating a movement of said sleeve in the generatrix direction of said sleeve without rotating, 
 wherein said regulation member has a regulation surface with which the edge surface of said sleeve contacts when said sleeve moves in the generatrix direction, 
 wherein the regulation surface of the regulation member is substantially perpendicular to a vertical virtual plane including all of the nip portion parallel to the moving direction, and 
 wherein the regulation surface of said regulation member has a curved-surface area in which a line when the regulation surface is cut in a virtual plane substantially parallel to the nip portion is a curved line convexed toward the edge surface of said sleeve. 
 
     
     
       2. An image heating apparatus according to  claim 1 , wherein the curved-surface area of the regulation surface has a shape obtained by cutting a part of a periphery of a virtual elliptic cylinder. 
     
     
       3. An image heating apparatus according to  claim 1 , wherein the curved-surface area faces the edge surface of an area farthest from an area surrounded by the nip portion of said flexible sleeve in a peripheral direction of said flexible sleeve. 
     
     
       4. An image heating apparatus according to  claim 1 , wherein said sliding member is a heat generating member. 
     
     
       5. An image heating apparatus according to  claim 1 , wherein said sleeve has a metallic layer. 
     
     
       6. An image heating apparatus according to  claim 1 , wherein said back-up member is a driving roller for driving said flexible sleeve.