Patent ID: 8741525

Claim:
A two-component developer system comprising a resin coated carrier and a toner, the resin coated carrier comprising: a carrier core; and a resin coating layer on a surface of the carrier core, the resin coated carrier being used with a toner in which an external additive having an average primary particle size of 50 nm or more is added to a toner particle, wherein the resin coating layer comprises two or more of a cross-linked silicone resin in combination, and the following expression (1) is satisfied: 0.5≦−log {( A/C )/( B/C )}≦2.5 (1) in which A represents a volume resistance value (Ω/cm) of the resin coated carrier in an electric field of 1000 V/cm that is obtained by conducting a stirring test, B represents a volume resistance value Ω/cm) of the resin coated carrier in an electric field of 1000 V/cm before the stirring test, and C represents a volume resistance value (Ω/cm) of the carrier core in an electric field of 1000 V/cm, wherein the stirring test is a test in which a developer that is obtained by mixing the resin coated carrier core and the toner so that a ratio of an entire projection area of the toner to an entire surface area of the carrier core is 70% is placed in a glass bottle, and mixed and stirred by a mixer mill under conditions of 26.3 Hz for three hours, wherein the carrier core is a ferrite and has a volume resistance value of 1.0×10 7 Ω/cm or more and 1.0×10 9 Ω/cm or less.