Development Apparatus Toner Layer Boundary Control
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Solution Overview
Problem
In image forming apparatuses using electrophotographic systems, the formation of a toner layer between the developer flowing layer and non-flowing layer at the restriction blade leads to unstable developer quantity and darkness fluctuations, as the toner layer grows and interferes with the gap, making it difficult to completely eliminate the non-flowing layer without compromising developer stability.
Innovation Solution
The development apparatus incorporates a method to regularly move the boundary surface between the developer flowing and non-flowing layers apart from the developing sleeve, utilizing a compartmented developer container with separate conveying screws to adjust the developer quantity and reduce the toner layer formation by altering the rotation speeds of the screws and the developing sleeve, ensuring the toner layer is eliminated before it interferes with the gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the restriction blade is used to restrict developer quantity at the developing sleeve, then stable developer quantity is supplied to the developing area, but a toner layer forms at the boundary surface between flowing and non-flowing layers, causing darkness fluctuations
Solution Approach 1:
The invention extracts and removes the harmful toner layer from the boundary surface between the developer flowing layer and non-flowing layer. The cleaning member is specifically designed to scrape off the toner layer that forms at this boundary, preventing it from interfering with the gap between the restriction blade and developing sleeve, thus eliminating darkness fluctuations while maintaining stable developer quantity supply.
Solution Approach 2:
The invention introduces a cleaning member as an intermediary element between the restriction blade and the developing sleeve. This cleaning member periodically removes the toner layer that forms at the boundary surface, acting as a mediator to prevent the harmful interaction between the toner layer and the gap, thereby resolving the contradiction between stable developer supply and toner layer formation.
2Object-generated harmful factors
If the developer non-flowing layer is completely eliminated, then darkness fluctuations are prevented, but developer quantity stability is compromised
Solution Approach 1:
The invention converts the harmful effect of the developer non-flowing layer into a beneficial one. Instead of trying to completely eliminate the non-flowing layer (which would compromise developer quantity stability), the invention allows it to exist but periodically removes the toner layer that forms at its boundary. This approach maintains the stabilizing effect of the non-flowing layer while preventing darkness fluctuations through selective toner layer removal.
3Quantity of substance
If the boundary surface moves closer to the developing sleeve, then developer quantity is increased, but toner layer growth interferes with the gap
Solution Approach 1:
The invention implements periodic action through the cleaning member that regularly moves along the developing sleeve to remove the toner layer at the boundary surface. This periodic cleaning prevents toner layer accumulation and interference with the gap, allowing the boundary surface to be positioned closer to the developing sleeve for increased developer quantity without the harmful effects of toner layer growth.
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 approach stabilizes the developer quantity conveyed to the developing area for long-term use by preventing toner layer growth and maintaining consistent image quality, reducing the occurrence of darkness fluctuations and developer non-flowing layer formation.
Implementation Method 1
The developer accommodated in the developer container is agitated and mixed by a conveying screw as a conveying member within the developer container
Implementation Method 2
The charged developer is borne mainly with magnetic force at a developing sleeve as the developer bearing member having a magnet as magnetic field generating unit arranged at the inside thereof
Implementation Method 3
the quantity of the developer conveyed to the developing area is adjusted to be restricted during a process of passing through a gap between the developing sleeve and the restriction blade
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3C
AI summary
In a development apparatus including conveying screws (25, 26) which circulates and conveys developer in a developer container (22) as being rotated, a developing sleeve (28) which bears and conveys developer in the developer container (22) as being rotated, and a restriction blade (30) which restricts developer quantity at the developing sleeve (28), the developer container (22) includes a supply chamber (23) to supply developer to the developing sleeve (28) and a retrieval chamber (24) to retrieve developer from the developing sleeve (28), and rotation speed of the conveying screws (25, 26) or rotation speed of the developing sleeve (28) is changed so that Vsc/Vsl during image forming is not performed is to be smaller than that during image forming is performed, as Vsc denotes the rotation speed of the conveying screws (25, 26) and Vsl denotes the rotation speed of the developing sleeve (28).