US 7,320,852 B2 | ||
Carrier for developer for developing electrostatic latent image, developer using same and image forming method using same | ||
Akihiro Kotsugai, Numazu (Japan); Kimitoshi Yamaguchi, Numazu (Japan); Naoki Imahashi, Mishima (Japan); and Hiroaki Takahashi, Sunto-gun (Japan) | ||
Assigned to Ricoh Company, Ltd., Tokyo (Japan) | ||
Filed on Mar. 21, 2003, as Appl. No. 10/392,869. | ||
Claims priority of application No. 2002-079898 (JP), filed on Mar. 22, 2002. | ||
Prior Publication US 2003/0224279 A1, Dec. 04, 2003 | ||
Int. Cl. G03G 9/10 (2006.01) |
U.S. Cl. 430—111.3 [430/111.35; 430/122.2; 430/122.4; 430/123.58] | 18 Claims |
1. A carrier for use with a toner as a two-component developer for developing an electrostatic image, comprising:
spherical magnetic core particles, and a resin layer covering each of said core particles and containing at least a first
resistance controlling material and a second resistance controlling material,
wherein the first resistance controlling material and the second resistance controlling materials have different specific
resistances,
wherein each of said first and second resistance controlling materials is in the form of particles having a number average
particle diameter of no more than 1/10 of a number average particle diameter of the toner,
wherein either the first or the second resistance controlling material is an Sn-doped titania, and
wherein the first resistance controlling material has a specific resistance of 1×103 Ω·cm or less and the second resistance controlling material has a specific resistance of 5×107 Ω·cm or less.
|