Patent attributes
A housing of a developing device has a circulating conveyance passage with a front conveyance passage along a developing roller and a rear conveyance passage parallel to the front conveyance passage. Front and rear spiral feeders are provided in the front and rear conveyance passages for conveying developer particles. The housing has a first developer inlet opening for receiving developer particles from a developer supplier and a second developer inlet opening for receiving recycled developer particles. The rear spiral feeder includes a conveyance power reduction portion at a position downstream from the first and second developer inlet openings and locally reduces conveyance power. The first and second developer inlet openings upstream of the conveyance power reduction portion and are where developer particles are likely to be upwardly surged due to the rotation of the rear conveyer.
