US 11,835,878 B2
Electrophotographic roller, process cartridge and electrophotographic image forming apparatus
Katsuya Kodama, Kanagawa (JP); Toshiro Suzuki, Shizuoka (JP); Kenichi Yazawa, Shizuoka (JP); and Atsushi Uematsu, Shizuoka (JP)
Assigned to CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Mar. 23, 2023, as Appl. No. 18/188,567.
Application 18/188,567 is a division of application No. 17/664,895, filed on May 25, 2022, granted, now 11,644,761.
Claims priority of application No. 2021-093293 (JP), filed on Jun. 2, 2021; and application No. 2022-076789 (JP), filed on May 6, 2022.
Prior Publication US 2023/0221660 A1, Jul. 13, 2023
Int. Cl. G03G 15/02 (2006.01); G03G 21/18 (2006.01); G03G 15/16 (2006.01)
CPC G03G 15/0216 (2013.01) [G03G 15/1685 (2013.01); G03G 21/1814 (2013.01); G03G 15/0233 (2013.01); G03G 2215/00135 (2013.01); G03G 2215/2051 (2013.01)] 16 Claims
OG exemplary drawing
 
1. An electrophotographic roller comprising a mandrel and an elastic layer on the mandrel, wherein
when defining a central position in a longitudinal direction of the mandrel as a central position O, and defining a position of the end portion of the elastic layer in a longitudinal direction of the elastic layer is defined as an end position X2, the elastic layer has a crown shape in which a diameter of the elastic layer decreases from the central position O to the end position X2,
when
a position between the central position O and the position X2 is defined as X1,
a distance between the central position O and the position X1 is defined as L1, and
a distance between the position X1 and the end position X2 is defined as L2, L1=0.6×(L1+L2), and
when
outer diameters of the electrophotographic roller at the central position O,
the position X1 and the end position X2 are defined as Do, DX1 and DX2, respectively, and Z1 and Z2 are defined as follows:
Z1=(Do−DX1)/2, and
Z2=(DX1−DX2)/2,
Z1, Z2, L1 and L2 satisfy a relationship of 1.000<[(Z2/L2)/(Z1/L1)]<1.931, and wherein
when a range from the central position O to the position X1 is defined as central region, and a range from the position X1 to the end position X2 is defined as an end region, a curvature of the elastic layer in the end region is smaller than a curvature of the elastic layer in the central region.