Developing Apparatus Partition Wall for Developer Discharge Control
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Solution Overview
Problem
In image forming apparatuses using a function separation type developing apparatus with a carrier refresh process, excessive discharge of developer leads to reduced developer supply to the developing sleeve, causing image defects like density unevenness and fogging due to degraded carrier charging performance.
Innovation Solution
The developing apparatus incorporates a configuration with a first and second chamber, conveyance members, and partition walls to form communication portions and a discharge port, allowing for controlled developer circulation and reduction of excessive discharge by promoting developer delivery from the agitating chamber to the developing chamber, even when the surface level is higher downstream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a discharge port is formed downstream of the agitating chamber to discharge surplus developer during ACR process, then carrier degradation is suppressed through carrier refresh, but developer is excessively discharged even when amount is small, causing insufficient developer supply to developing sleeve
Solution Approach 1:
The partition wall divides the agitating chamber into an upstream region and a downstream region, segmenting the developer circulation path. This allows selective discharge of surplus developer from the upstream region while maintaining sufficient developer supply to the developing chamber, resolving the contradiction between carrier refresh and developer quantity maintenance.
Solution Approach 2:
The partition wall acts as an intermediary structure that controls developer flow between regions. It enables the discharge port to selectively remove surplus developer while preventing excessive discharge, thereby maintaining both carrier refresh functionality and adequate developer supply to the developing sleeve.
2Quantity of substance
If developer circulation is promoted from agitating chamber to developing chamber, then excessive discharge is reduced and developer supply is maintained, but developer accumulation downstream of agitating chamber occurs due to higher surface level
Solution Approach 1:
By segmenting the agitating chamber into upstream and downstream regions with the partition wall, the invention controls developer distribution more uniformly. The partition wall prevents excessive accumulation in the downstream region while maintaining adequate supply to the developing chamber, addressing both developer quantity and distribution uniformity.
Solution Approach 2:
The partition wall creates different local conditions in upstream and downstream regions of the agitating chamber. The upstream region allows controlled discharge of surplus developer, while the downstream region maintains sufficient developer for developing chamber supply, achieving local optimization of developer distribution.
Data Source
AI summary
A developing apparatus includes a rotatable developer carrying member, a first chamber to supply developer to the developer carrying member, and a second chamber to collect the developer from the developer carrying member. A first conveyance screw in the first chamber conveys the developer in a first conveyance direction, and a second conveyance screw conveys the developer in the second chamber. The second conveyance screw includes a rotary shaft, a first vane portion, and a second vane portion provided downstream of the first vane portion. A developer discharge portion is disposed upstream of the second vane portion in the first conveyance direction and discharges excess developer. The developer discharge portion is disposed in a predetermined area of the second chamber in which the developer is deliverable to a communication portion, and is provided in a bottom portion in the predetermined area of the second chamber.