Conveyance Screw with Variable Thread Density for Developer Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In image forming apparatuses, the accumulation of developer at the delivery portion leads to a high developer surface level in the collecting chamber, causing entrainment by the developing sleeve and resulting in image defects due to reduced fluidity and uneven toner density.
Innovation Solution
A developing apparatus with a rotatable developer bearing member, a developing chamber, and a collecting chamber, featuring a first communication port out of the developing area, a first conveyance screw, and a second conveyance screw with more threads facing the communication port to enhance developer delivery and circulation, preventing accumulation and maintaining a low surface level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of threads of the agitating screw is reduced to increase conveyance force, then the developer surface level is lowered at the developing area, but the delivery efficiency decreases and developer accumulates at the deliver portion
Solution Approach 1:
The agitating screw is designed with different number of threads in different axial regions. The first screw portion (upstream) has a first number of threads optimized for conveying developer without accumulation, while the second screw portion (downstream near deliver portion) has a second number of threads optimized for maintaining high developer surface level to prevent entrainment. This local differentiation resolves the contradiction between lowering surface level and maintaining delivery efficiency.
2Object-affected harmful factors
If the developer surface level becomes too high within the collecting chamber, then the developer is entrained by the developing sleeve causing image defects, but reducing the number of threads of the agitating screw to lower the surface level causes developer accumulation at the deliver portion
Solution Approach 1:
The agitating screw implements local quality by having different thread configurations in different regions. The upstream region uses fewer threads to prevent accumulation, while the downstream region uses more threads to maintain appropriate surface level and prevent entrainment. This spatial differentiation of screw properties simultaneously addresses both harmful effects.
Solution Approach 2:
The agitating screw is segmented into multiple portions along its axial direction, with each portion having a specific number of threads optimized for its location. This segmentation allows independent optimization of different regions to prevent both accumulation and entrainment simultaneously.
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
The solution effectively restrains developer accumulation, maintains a low surface level, and prevents image defects by accelerating developer delivery and circulation, ensuring efficient toner distribution and image quality.
Implementation Method 1
a second conveyance screw disposed within the collecting chamber, including a first screw portion having a first number of threads, configured to convey the developer in a second direction opposite to the first direction
Data Source
AI summary
A developing apparatus includes a rotatable developer bearing member, a first conveyance screw in a first chamber to convey the developer, and a second conveyance screw in a second chamber to convey the developer. The second conveyance screw includes a first screw portion facing a communication portion between the first and second chambers, a second screw portion downstream of the first screw portion, and a third screw portion downstream of the first screw portion and upstream of the second screw portion and facing the second communication portion. The first screw portion includes a first blade portion formed spirally around a rotation shaft of the second conveyance screw, the second screw portion has a second blade portion formed spirally around the rotation shaft of the second conveyance screw, and the third screw portion comprises no blade portion formed spirally around the rotation shaft of the second conveyance screw.