Developer Guiding Portion Agitation in Electrophotographic Apparatus
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Solution Overview
Problem
In electrophotographic developing apparatuses, the recovery of developer from the developing sleeve often leads to uneven developer density and image defects due to inadequate agitation of the developer in the second chamber, causing heterogeneous toner distribution and surface layer issues.
Innovation Solution
The developing apparatus incorporates a second conveyance member that overlaps with the first conveyance member, a transfer portion, and an extended portion on the partition to facilitate the agitation and circulation of the developer, ensuring that the recovered developer is effectively mixed with the surrounding developer before being transferred back to the first chamber, promoting homogeneity and preventing surface layer stagnation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the recovered developer falls near the communication path having a high developer surface, then the structure is simple, but the recovered developer moves in floating motion on the surface layer and flows into the first conveyance path in a state not sufficiently agitated
Solution Approach 1:
The patent introduces an extended portion of the partition as an intermediary structure between the second conveyance path and the communication path. This extended portion creates a barrier that prevents the recovered developer from directly floating on the surface layer near the communication path, forcing it to be properly agitated by the second conveyance member first before being transferred to the first chamber.
Solution Approach 2:
The extended portion of the partition is positioned upstream of the communication path to perform preliminary action by blocking the direct path of recovered developer. This ensures that the developer is agitated and mixed in the second chamber before reaching the transfer point, preventing premature transfer in an unagitated state.
2Quantity of substance
If the developer surface is raised toward the downstream side in the second chamber, then the developer circulation is maintained, but the agitation of the developer near the surface layer is not easily promoted at the downstream portion
Solution Approach 1:
The extended portion of the partition introduces a vertical dimension barrier that protrudes into the second chamber. This creates a three-dimensional obstruction that disrupts the horizontal floating motion of developer particles, forcing them to engage with the second conveyance member for proper agitation before reaching the downstream area.
Solution Approach 2:
The extended portion creates a localized region of increased agitation by positioning it specifically at the upstream part of the second chamber near the communication path. This local modification enhances the agitation effect precisely where the recovered developer enters, without affecting the overall circulation pattern in other regions.
3Productivity
If the recovered developer with low toner density flows into the first conveyance path without sufficient agitation, then the transfer efficiency is high, but the developer becomes heterogeneous and causes unevenness of density or other image defects
Solution Approach 1:
The extended partition acts as an intermediary barrier that mediates between the recovered developer and the communication path. It prevents direct, unagitated transfer while allowing proper agitation to occur first, thus maintaining transfer efficiency only after the developer has been sufficiently mixed and homogenized in the second chamber.
Solution Approach 2:
The extended portion performs preliminary anti-action by opposing the natural floating motion of recovered developer toward the communication path. This counter-action forces the developer to be agitated downward and mixed properly before transfer, preventing the harmful effect of heterogeneous developer reaching the first conveyance path.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the agitation of the developer, maintaining image quality by preventing uneven toner density and reducing image defects, as demonstrated by improved image density and reduced density unevenness in comparative experiments.
Implementation Method 1
a first conveyance member arranged in the first chamber and configured to convey the developer while agitating the developer
Implementation Method 2
a second conveyance member arranged in the second chamber such that at least a portion of the second conveyance member is overlapped with the first conveyance member in a state viewed from a horizontal direction, the second conveyance member being configured to convey the developer while agitating the developer
Implementation Method 3
a magnet roll configured to repel the developer borne on the developing sleeve and fall into a recovery plate having an inclined plane
Data Source
AI summary
A developing apparatus includes a developer bearing member, a first chamber to supply the developer to the developer bearing member, and a second chamber to collect the developer having passed through a developing region. A guiding portion is arranged on a partition portion that separates the first and second chambers. The guiding portion guides the developer from the developer bearing member to the second chamber, and is positioned overlapping a communicating portion between the first and second chambers. One end portion of the guiding portion is arranged above an upper end of the partition portion, and the other end portion of the guiding portion is arranged above a rotation axis of a conveyance screw in the second chamber and below an uppermost portion of the conveyance screw while leaving a clearance between the guiding portion and the conveyance screw.