	US 7,570,905 B2
	Developing roller, developing apparatus using the same, and image forming apparatus
Takashi Kusaba, Suntou-gun (Japan); Ryota Kashiwabara, Susono (Japan); and Minoru Nakamura, Suntou-gun (Japan)
Assigned to Canon Kabushiki Kaisha, Tokyo (Japan)
Filed on Apr. 02, 2008, as Appl. No. 12/61,385.
Application 12/061385 is a continuation of application No. PCT/JP2007/068004, filed on Sep. 10, 2007.
Claims priority of application No. 2006-275524 (JP), filed on Oct. 06, 2006.
Prior Publication US 2008/0193172 A1, Aug. 14, 2008
Int. Cl. G03G 15/08 (2006.01)

U.S. Cl. 399—286 [430/123.3]

11 Claims

1. A developing roller having an elastic layer on the outer periphery of a mandrel and having a surface layer containing a resin and resin particles on the outer periphery thereof,

wherein the surface layer has a convex portion attributable to the resin particles, and has a surface of roughness in which a distortion degree Rsk of a roughness curve is 0.15 or more and 0.70 or less,

wherein the resin particles have a peak P1 at a particle diameter d1 in a volume particle size distribution, and wherein “a”, “b”, “c”, d1, d2 and d3 satisfy the following relational formulas:

4 μm≤d2−d1≤12 μm

6 μm≤d1≤22 μm

10 μm≤d2≤27 μm

2.0 Vol. %≤b ≤8.0 Vol. %

1.5≤a/b≤7.0

0.0≤c/b≤1.1, and

d1<d3<d2

where, “a” denotes a volume fraction of the resin particle having the particle diameter d1 in the volume particle size distribution, and “b” and “c” denote volume fractions at particle diameters d2 and d3 respectively in the volume particle size distribution,

wherein, “A”, “t” and “B” satisfy the following formulas:

15≤A≤40

8.0≤t≤15.0

3.0≤A×B/100≤9.0,

where, “A” denotes a blending quantity of the resin particle relative to the resin 100 parts by mass,

“t” denotes the thickness of the surface layer in microns, and

“B” denotes the volume fraction of the resin particle having a particle diameter not less than 1.2 times the thickness of the surface layer in the volume particle size distribution.