Ricoh Company, Ltd.

Masakazu Yashiro

Mitsuo Aoki

Shinichi Kuramoto

Nobuyasu Makino

Akira Oyamaguchi

Kazuo Kuratani

Hiroshi Sugimoto

A classification device for classifying particles by size including an upper impeller-type rotor, a first end of which is covered with a cover disc without penetration hole and a second end of which is covered with an upper cover disc with a penetration hole; and a lower impeller-type rotor, a first end of which is covered with a cover disc without penetration hole and a second end of which is covered with a lower cover disc with a penetration hole. The upper impeller-type rotor and the lower impeller-type rotor are provided so that axes thereof are coincident and the first ends face with each other forming a gap therebetween in an axial direction, and the diameters of the penetration holes of the upper cover disc and the lower cover disc are different.

Classification device

A color developer is described that contains a toner and a resin-coated carrier, wherein the toner contains a hydrophobic particulate titania and a charge controlling agent, and the charge controlling agent contains an aromatic hydroxycarboxylic acid metal salt having the following formula (1): ##STR1## wherein each of Q and Q' each independently represents a residual group of an aromatic hydroxycarboxylic acid optionally substituted with an alkyl group, an aralkyl group, or an alkyl group and an aralkyl group; X is a counter ion; and M is a metal. A toner is also provided that contains the above charge controlling agent.

Dry developer for developing electrostatic latent image

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Shizuoka-ken, Japan

Masakazu Yashiro