US Patent 7349655 Developing device and method of forming images

A developing device configured to carry out development of an electrostatic image using color toner particles and transparent toner particles includes color and transparent developing units configured to store toner particles, carrier particles, and additive particles and configured to carry out development of the electrostatic image; color and transparent developer replenishment containers configured to store replenishment developers including at least the toner particles and the carrier particles and configured to replenish developing units with the replenishment developers; and color and transparent developers openings provided at the developing units and configured to discharge the developers in the developing units outside the developing units while replenishing the developing units with the replenishment developers, wherein the carrier particle weight ratio of the transparent replenishment developer is higher than the carrier particle weight ratio of the color replenishment developer.