Dual Conveying Member Developer Stirring for Uniform Toner
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Solution Overview
Problem
In electrophotographic image forming apparatuses, maintaining uniform toner concentration and stable developer conveying is challenging, leading to uneven image density and quality issues due to inadequate developer stirring and toner concentration detection.
Innovation Solution
A developing device with a dual conveying system and a headless toner concentration sensor, where the first and second conveying members are designed to stir the developer in opposite directions within the development container, and the toner concentration sensor is strategically placed to detect toner concentration accurately, ensuring consistent developer supply and image formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single conveying member is used to convey developer, then the device structure is simple, but the developer stirring is insufficient leading to uneven toner concentration
Solution Approach 1:
The single conveying member is divided into two separate conveying members (first conveying member and second conveying member) that operate in parallel. Each conveying member stirs the developer in its respective chamber, ensuring more uniform toner distribution throughout the developer reservoir while maintaining relatively simple individual component structures.
2Ease of manufacture
If the toner concentration sensor is placed in the center of the conveying chamber, then the sensor placement is simple, but the sensor interferes with the developer flow and conveying efficiency
Solution Approach 1:
The toner concentration sensor is positioned at a specific location on the inner wall of the conveying chamber, away from the center and in a region where it does not interfere with the developer flow path. This localized positioning allows the sensor to accurately detect toner concentration while minimizing its interference with the conveying members' stirring action and overall developer circulation efficiency.
3Productivity
If the conveying member has a large outer diameter, then the conveying capacity is high, but the space for sensor placement and developer circulation is reduced
Solution Approach 1:
The conveying members are designed with optimized dimensional proportions, where the outer diameter is controlled to maintain adequate circulation space. The system compensates for any space constraints by optimizing the axial length and the pitch of the conveying blades, effectively distributing the conveying capacity across multiple dimensions rather than relying solely on a large outer diameter.
4Speed
If the pitch of the conveying blade is large, then the developer conveying speed is high, but the stirring effectiveness is reduced leading to poor toner distribution
Solution Approach 1:
The pitch of the conveying blades is optimized to a specific range (0.5 to 2.0 times the outer diameter) that balances conveying speed and stirring effectiveness. This parameter optimization ensures that the developer is moved through the chamber at an adequate speed while the blade geometry maintains effective mixing action, resulting in uniform toner distribution throughout the developer reservoir.
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 stable developer conveying, reduces image density variations, and achieves high-quality image formation by maintaining uniform toner concentration and preventing sensor interference with developer flow.
Implementation Method 1
The first conveying member is rotatably arranged in the first conveying chamber, and conveys, while stirring, the developer in the first conveying chamber in a first direction along the longitudinal direction of the first conveying chamber
Implementation Method 2
The second conveying member is rotatably arranged in the second conveying chamber, and conveys, while stirring, the developer in the second conveying chamber in a second direction along the longitudinal direction of the second conveying chamber, the second direction being opposite to the first direction
Implementation Method 3
The toner concentration sensor is arranged at a wall portion of the first conveying chamber along the first direction, and detects a toner concentration of the developer
Implementation Method 4
The developer carrier is rotatably supported in the development container, and carries thereon the developer in the second conveying chamber
Data Source
AI summary
A development device includes a development container, a first conveying member, a second conveying member, a toner concentration sensor, and a developer carrier. The first and second conveying members are equal to each other in outer diameter and shaft diameter, the outer diameter being 1.3 times the shaft diameter or more but 1.6 times the shaft diameter or less. Where L represents an axial length of the first conveying member, K represents a distance of a center position of the sensing surface of the toner concentration sensor from a downstream end of a first conveying chamber of the development container in the first direction, P represents a pitch of the conveying blade of the first conveying member, and R represents a rotational speed of the first conveying member, formula (1) is satisfied: 30000<(P×R×L)/K<45000 (1).