Patent ID: 8200130
Filing Date: 2012-06-12
Classification: G03G

Abstract:
1. A developing device, comprising: a first toner carrier for carrying toner on a surface thereof, to develop with the toner, an electrostatic latent image formed on an image carrier; a second toner carrier for carrying toner on a surface thereof to develop with the toner, the electrostatic latent image formed on the image carrier; and a developer carrier that faces the first toner carrier and the second toner carrier, and is adapted to carry developer in a thin layer on a surface thereof to supply toner contained in the developer to the first toner carrier and the second toner carrier; wherein the first toner carrier is disposed so as to face the developer carrier at an upstream position relative to a rotating direction of the developer carrier; wherein the second toner carrier is disposed so as to face the developer carrier at a downstream position relative to the rotating direction of the developer carrier, wherein a counter-charge generated by the supply of toner from the developer on the developer carrier in the developer at a first facing area between the developer carrier and the first toner carrier, remains without decreasing to a zero level in the developer until the counter-charge is conveyed to a second facing area between the developer carrier and the second toner carrier; and the following relationship is satisfied: where τ is a damping time constant of surface charge on the thin layer of the developer carried and conveyed on the developer carrier; and where t12 is a time taken for the developer on the developer carrier to travel from the first facing area to the second facing area.