Sheet conveyance apparatus and image forming apparatus

Abstract

A sheet conveyance apparatus includes a first rotary member pair comprising a first nip portion and configured to convey a sheet, a second rotary member pair comprising a second nip portion and configured to convey the sheet being conveyed by the first rotary member pair, and a conveyance guide including a first conveyance guide portion forming a loop space and a second conveyance guide portion arranged downstream of the first conveyance guide portion in the sheet conveyance direction and forming a curved conveyance path. A first intersection at which a first straight line and a third straight line intersect is positioned within the loop space, and a second intersection at which the first straight line and a second straight line intersect is positioned outside the conveyance path.

What is claimed is: 
     
         1 . A sheet conveyance apparatus comprising:
 a first rotary member pair comprising a first nip portion and configured to convey a sheet;   a second rotary member pair arranged downstream of the first rotary member pair in a sheet conveyance direction, comprising a second nip portion and configured to convey the sheet being conveyed by the first rotary member pair; and   a conveyance guide configured to guide the sheet having passed through the first nip portion to the second nip portion, and forming a curved conveyance path, the conveyance guide comprising a first conveyance guide portion and a second conveyance guide portion arranged downstream of the first conveyance guide portion in the sheet conveyance direction, the conveyance path including a loop space in which a sheet abutted against the second nip portion is capable of forming a loop,   wherein in the conveyance path, the first rotary member pair and the second rotary member pair are arranged adjacently,   the second nip portion is positioned upward than the first nip portion in a vertical direction and positioned at a position different from the first nip portion in a horizontal direction,   the conveyance guide is arranged on an outer side of the curved conveyance path between the first nip portion and the second nip portion,   the sheet conveyed by the first rotary member pair is abutted against the second nip portion so as to correct skewing of the sheet,   if a common tangent of the first rotary member pair at the first nip portion is referred to as a first straight line, a common tangent of the second rotary member pair at the second nip portion is referred to as a second straight line, and a straight line that passes an intersection of the second straight line and the conveyance guide and has an inclination corresponding to the second conveyance guide portion is referred to as a third straight line,   the second straight line and the third straight line intersect each other,   the loop space is arranged upstream of the intersection of the second straight line and the conveyance guide in the sheet conveyance direction,   a first intersection at which the first straight line and the third straight line intersect is positioned within the loop space, and   a second intersection at which the first straight line and the second straight line intersect is positioned outside the conveyance path.   
     
     
         2 . The sheet conveyance apparatus according to  claim 1 , wherein a minor angle formed by the first straight line and the third straight line is greater than a minor angle formed by the second straight line and the third straight line. 
     
     
         3 . The sheet conveyance apparatus according to  claim 1 , wherein the first conveyance guide portion is bulged toward a direction away from the first straight line so as to form the loop space, and
 the first straight line intersects with the second conveyance guide portion.   
     
     
         4 . The sheet conveyance apparatus according to  claim 3 , wherein the second conveyance guide portion is configured to contact the sheet and receive load from the sheet in a state where the sheet is abutted against the second nip portion and sagged by its own weight. 
     
     
         5 . The sheet conveyance apparatus according to  claim 3 , wherein a leading edge of the sheet conveyed by the first rotary member pair is guided by the first conveyance guide portion to the second conveyance guide portion, and then, guided by the second conveyance guide portion to the second nip portion. 
     
     
         6 . The sheet conveyance apparatus according to  claim 3 , wherein the first conveyance guide portion is formed in a curved shape and formed continuously with an upstream end, in the sheet conveyance direction, of the second conveyance guide portion, and
 the first intersection is arranged upstream than the upstream end of the second conveyance guide portion in the sheet conveyance direction.   
     
     
         7 . The sheet conveyance apparatus according to  claim 6 , wherein the second conveyance guide portion is a flat surface. 
     
     
         8 . The sheet conveyance apparatus according to  claim 7 , wherein the second conveyance guide portion extends not to parallel with the first and second straight lines, and
 the first and second nips are positioned on one side with respect to the third straight line.   
     
     
         9 . The sheet conveyance apparatus according to  claim 1 , wherein the loop space is greater than a conveyance space formed between the conveyance guide and the second rotary member pair. 
     
     
         10 . An image forming apparatus comprising:
 the sheet conveyance apparatus according to  claim 1 ; and   an image forming unit configured to form an image on a sheet conveyed by the sheet conveyance apparatus.