Developing Roller Shifting Electric Field Ghost Image Suppression
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Solution Overview
Problem
Conventional electrophotographic image forming apparatuses face issues with toner distribution and image quality due to ghost images caused by toner consumption history on the developing roller, leading to inconsistent halftone images and reduced image quality.
Innovation Solution
A developing device with a developing roller and conveyor roller system, where alternating-current bias is superimposed on direct-current bias to create a shifting electric field, moving toner from the developing roller to the conveyor roller, thereby eliminating toner history and reducing ghost image generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional developing roller system is used, then structure is simple, but ghost images occur due to toner consumption history
Solution Approach 1:
The developing device is divided into two separate rollers: a developing roller for supplying toner to the photoconductive drum and a conveyor roller for supplying developer to the developing roller. This segmentation allows independent optimization of each roller's function, eliminating ghost images while maintaining structural simplicity
Solution Approach 2:
The conveyor roller acts as an intermediary between the developer stirring unit and the developing roller. It receives developer, regulates layer thickness, and supplies it to the developing roller, preventing toner consumption history from being transferred to the photoconductive drum
2Productivity
If toner is supplied continuously to photoconductive drum, then developing speed is high, but toner distribution becomes inconsistent
Solution Approach 1:
The conveyor roller preliminarily processes the developer by regulating its layer thickness before supplying it to the developing roller. This preliminary action ensures uniform toner distribution on the photoconductive drum surface, maintaining manufacturing precision while enabling continuous high-speed development
Solution Approach 2:
The system changes the physical parameters of developer delivery by using magnetic fields to control developer flow and layer thickness on the conveyor roller. This parameter control ensures consistent toner distribution while maintaining high developing speed
3Productivity
If magnetic field is used for developer transfer, then transfer efficiency is high, but magnetic pole arrangement complexity increases
Solution Approach 1:
The magnetic pole arrangements on the conveyor roller and developing roller are segmented into specific patterns (N-S-N-S sequence) that create efficient magnetic fields for developer transfer. This segmented arrangement achieves high transfer efficiency while maintaining manageable structural complexity
Solution Approach 2:
Different magnetic pole arrangements are applied to different regions of the conveyor roller and developing roller according to their specific functional requirements. The conveyor roller uses an arrangement optimized for receiving and regulating developer, while the developing roller uses an arrangement optimized for supplying toner to the photoconductive drum
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 suppresses ghost image formation, improving image quality by ensuring consistent toner distribution and reducing toner consumption history on the developing roller, enhancing the overall performance of the electrophotographic image forming apparatus.
Implementation Method 1
The developer supplied from the developer stirring unit to the conveyor roller is transferred from the conveyor roller to the developing roller by a magnetic field formed by the second and third magnetic poles
Implementation Method 2
The developer having passed through the developing position is transferred from the developing roller to the conveyor roller by a magnetic field formed by the first and fourth magnetic poles
Implementation Method 3
The development bias applying unit applies the development biases such that a shifting electric field to move the toner on the first sleeve of the developing roller toward the second sleeve of the conveyor roller is formed at the facing position during the developing operation
Data Source
AI summary
A developing device includes a developing roller, a conveyor roller, a developer stirring unit and a development bias applying unit. The developing roller is arranged to face a photoconductive drum at a predetermined developing position and supplies the toner. The conveyor roller is arranged to face the developing roller at a predetermined facing position and supplies the developer to the developing roller. The development bias applying unit applies development biases to the first sleeve of the developing roller and the second sleeve of the conveyor roller during a developing operation of developing the electrostatic latent image on the photoconductive drum with the toner. The development bias applying unit applies the development biases such that a shifting electric field to move the toner on the first sleeve of the developing roller toward the second sleeve of the conveyor roller is formed at the facing position during the developing operation.