Dual Conveying Member Development Device for Toner Concentration Control
Find Innovative SolutionsGenerate Solutions
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 is employed, where the first and second conveying members stir the developer in opposite directions within the development container, and the toner concentration sensor detects the toner concentration accurately, ensuring consistent developer supply and image formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single conveying member is used to convey developer, then the device structure is simple, but the developer stirring effectiveness is insufficient leading to uneven toner concentration
Solution Approach 1:
The development container is divided into a first conveying chamber and a second conveying chamber, each with its own conveying member. The first conveying member conveys developer in a forward direction while the second conveying member conveys developer in a reverse direction, creating opposing flow patterns that enhance mixing and uniformity of toner concentration without requiring complex mechanical stirring mechanisms.
2Measurement precision
If the toner concentration sensor is positioned at the center of the first conveying chamber, then the detection structure is simple, but the detection accuracy is insufficient due to inadequate developer circulation at the center
Solution Approach 1:
The sensor position is pre-calculated and positioned downstream from the center of the first conveying chamber based on the relationship (500L²×K)/D⁴≥1.0. This preliminary positioning ensures the sensor is located in a region where developer circulation is optimized, providing accurate toner concentration detection before the developer reaches the conveying member, thereby maintaining detection accuracy without requiring real-time adjustment mechanisms.
3Productivity
If the outer diameter of conveying members is large, then the developer conveying capacity is high, but the stirring effectiveness is reduced
Solution Approach 1:
Two conveying members rotate in opposite directions with optimized outer diameters between 2.3 to 3.0 times the shaft diameter. This dynamic configuration creates opposing flow fields that enhance mixing effectiveness while maintaining sufficient conveying capacity. The reverse rotation of the second conveying member compensates for the reduced stirring effect of individual large-diameter members, achieving both high productivity and uniform developer 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 stable and uniform image density with reduced density followability and variation, achieving high-quality image formation by maintaining optimal toner concentration and developer distribution.
Implementation Method 1
The toner concentration sensor is a headless sensor and has a sensing surface embedded in an inner wall surface of the first conveying chamber. A center of the sensing surface of the toner concentration sensor is located in a region extending downstream, in the first direction, from a center of the first 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 toner concentration sensor is arranged at a wall portion of the first conveying chamber in which the first conveying member is arranged. The first and second conveying members are equal to each other in outer diameter and shaft diameter, the outer diameter being 2.3 times the shaft diameter or more but 3.0 times the shaft diameter or less. Where D represents the shaft diameter of the first conveying member, L represents an axial length of the first conveying member, and K represents a distance of a center position of a sensing surface of the toner concentration sensor from a downstream end of the first conveying chamber in the first direction, formula (1) is satisfied: 500<(L2×K)/D4<2500 (1).