Tapered Stirring Shaft for Uniform Developer Mixing
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Solution Overview
Problem
In two-component developing devices, dense image development leads to uneven toner concentration and insufficient stirring, causing image density unevenness and background fogging.
Innovation Solution
The developing device incorporates a development container with a first and second conveyance chamber, each equipped with a stirring conveyance member, and a tapered rotation shaft in the first conveyance chamber to ensure thorough stirring and conveyance of the developer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large amount of toner is supplied to the development container at one time for dense image development, then the productivity is improved, but the toner concentration becomes uneven and stirring becomes insufficient
Solution Approach 1:
The development container is divided into a first conveyance chamber and a second conveyance chamber separated by a partition portion. The first stirring conveyance member operates in the first chamber while the second stirring conveyance member operates in the second chamber, enabling independent stirring control in each segment to maintain uniform toner concentration even when large amounts of toner are supplied.
Solution Approach 2:
The first rotation shaft has a tapered portion with diameter increasing toward the downstream side, creating variable stirring intensity along the conveyance direction. This dynamic geometric design enhances stirring effectiveness in regions where toner concentration tends to be higher, ensuring uniform mixing throughout the development container.
2Device complexity
If toner and carrier are not sufficiently stirred in the development container, then the device complexity is reduced, but background fogging occurs and image quality deteriorates
Solution Approach 1:
The stirring function is segmented between two independent stirring conveyance members operating in separate chambers. This segmentation allows each member to be relatively simple in design while collectively providing sufficient stirring throughout the entire development container, preventing background fogging without requiring an overly complex single stirring mechanism.
Solution Approach 2:
The first and second stirring conveyance members work together in a coordinated manner, with the first member handling initial stirring in the first chamber and the second member completing the stirring process in the second chamber. This combination of two simpler stirring mechanisms achieves the same reliability effect as a single complex stirring system would provide.
3Device complexity
If a single stirring conveyance member is used in the development container, then the device complexity is reduced, but insufficient stirring occurs leading to toner concentration unevenness
Solution Approach 1:
The development container is divided into two conveyance chambers with each having its own stirring conveyance member. This segmentation allows distributed stirring action throughout the container, ensuring uniform developer composition without requiring a single overly complex stirring mechanism that would be difficult to design and implement.
Solution Approach 2:
The partition portion acts as an intermediary structure that separates the two stirring zones while still allowing the overall stirring function to work together. The communication portions at opposite ends of the partition allow developer flow between chambers, coordinating the action of both stirring members to achieve uniform mixing.
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 ensures sufficient stirring of the developer, maintaining even toner concentration and preventing image density unevenness and background fogging.
Implementation Method 1
The first stirring conveyance member includes a first rotation shaft rotatably supported in the first conveyance chamber and a first stirring blade formed on an outer circumferential surface of the first rotation shaft, and the first stirring conveyance member stirs and conveys the developer in the first conveyance chamber
Implementation Method 2
The second stirring conveyance member includes a second rotation shaft rotatably supported in the second conveyance chamber and a second stirring blade formed on an outer circumferential surface of the second rotation shaft, and the second stirring conveyance member stirs and conveys the developer in the second conveyance chamber
Implementation Method 3
The first rotation shaft has, at least in a partial region in an axial direction of the first rotation shaft, a tapered portion of which a shaft diameter increases toward a downstream side in a developer conveyance direction in the first conveyance chamber
Data Source
AI summary
A developing device (3a-3d) is provided with a development container (20), a first stirring conveyance member (25), a second stirring conveyance member (26), and a developer carrier (31). The development container (20) has a first conveyance chamber (21), a second conveyance chamber (22), and a communication portion (20). The first stirring conveyance member (25) includes a first rotation shaft (23a) and a first stirring blade (24a). The second stirring conveyance member (26) includes a second rotation shaft (23b) and a second stirring blade (24b). The developer carrier (31) is opposed to the second stirring conveyance member (26). The first rotation shaft (23a) includes, at least in a partial region in an axial direction of the first rotating shaft (23a), a tapered portion (36) of which a shaft diameter increases toward a downstream side in a developer conveyance direction in the first conveyance chamber (21).