Patent ID: 7539440
Filing Date: 2009-05-26
Classification: G03G

Abstract:
1. A developing unit comprising: a magnetic monocomponent developer which includes a developing vessel which accommodates a magnetic monocomponent developer therein, a developer carrying body which carries the magnetic monocomponent developer and conveys the magnetic monocomponent developer to a developing region, and a developer layer thickness restricting member which restricts a layer thickness of the magnetic monocomponent developer, wherein the magnetic monocomponent developer includes toner particles which contain at least a first polyester resin having a weight average molecular weight within a range from 1.0×10 (a) an average particle size of the toner particles being set to a value which falls within a range from 6 to 9 μm; (b) an average degree of circularity of the toner particles being set to a value which falls within a range from 0.950 to 0.960; and (c) a content of the toner particles having a degree of circularity of below 0.850 being set to a value which falls within a range from 2.0 to 4.0 unit % with respect to a total quantity of the toner particles.