DEVELOPING UNIT, PROCESS CARTRIDGE, AND IMAGE FORMING APPARATUS

摘要

A developing unit includes a developer bearer to bear developer on a surface thereof, first and second developer conveyors each having a spiral blade mounted on a rotary shaft thereof parallel to a rotary axis of the developer bearer to convey developer in opposite directions to each other. A developer drain hole is provided at a given height in a side wall of a second developer conveyance channel to face a communication opening across the second developer conveyor. The first developer conveyor rotates in a direction with its spiral blade rising between the rotary shaft of the first developer conveyor and the communication opening. Rotational phases of the first developer conveyor and the second developer conveyor are fixed and synchronized with each other to weaken momentum of developer flow generated by the first developer conveyor toward the developer drain hole via the second developer conveyor.

主权项

1. A developing unit comprising:
a developer bearer to bear developer on a surface thereof; a first developer conveyor having a spiral blade mounted on a rotary shaft thereof parallel to a rotary axis of the developer bearer to convey developer in a first direction; a second developer conveyor having a spiral blade mounted on a rotary shaft thereof parallel to the rotary axis of the developer bearer to convey developer in a second direction opposite the first direction; a first developer conveyance channel including the first developer conveyor; a second developer conveyance channel including the second developer conveyor; a partition wall to separate the first developer conveyance channel and the second developer conveyance channel from each other; a communication opening formed in the partition wall to communicate the first developer conveyance channel with the second developer conveyance channel at a position near a downstream end of the first developer conveyance channel including the first developer conveyor and an upstream end of the second developer conveyance channel including the second developer conveyor, each of the downstream end and the upstream end horizontally aligned with each other; and a developer drain hole to drain the developer from the developing unit, the developer drain hole provided at a given height in a side wall of the second developer conveyance channel to face the communication opening across the second developer conveyor, wherein the first developer conveyor rotates in a direction with the spiral blade thereof rising between the rotary shaft of the first developer conveyor and the communication opening, wherein rotational phases of the first developer conveyor and the second developer conveyor are fixed and synchronized with each other to weaken momentum of developer flow generated by the first developer conveyor toward the developer drain hole via the second developer conveyor.