Magnetic Roller Surface Roughness for Toner Collection
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Solution Overview
Problem
Conventional developing devices in image forming apparatuses experience developer accumulation between the developing roller and magnetic roller, leading to contamination and carrier adherence on image bearing members.
Innovation Solution
A developing device using a two-component developer with a magnetic roller having a surface roughness greater than the developing roller, where both rollers are rotationally driven in opposite directions with differing magnetic polarities, forming a strong magnetic brush to prevent developer accumulation and enhance toner collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic poles with different polarities are provided in the developing roller and magnetic roller to improve binding force of magnetic brush, then toner collection ability is improved, but developer accumulates in the periphery between the rollers causing contamination and carrier adherence
Solution Approach 1:
The invention changes the physical parameter of surface roughness, making the magnetic roller's surface roughness greater than the developing roller's surface roughness. This parameter change modifies the magnetic brush structure and toner distribution, preventing developer accumulation in the periphery while maintaining effective toner collection through the magnetic field interaction between oppositely polarized rollers.
2Force
If developer accumulates in the periphery between the developing roller and magnetic roller, then binding force of magnetic brush is improved, but developer blows out to contaminate the image forming apparatus and causes carrier adherence
Solution Approach 1:
By changing the surface roughness parameter of the magnetic roller to be greater than that of the developing roller, the invention controls the distribution of developer within the magnetic brush. This prevents excessive developer accumulation in the periphery that would otherwise blow out and cause contamination, while preserving the necessary binding force for effective toner collection through the magnetic field interaction between oppositely polarized rollers.
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
Prevents developer accumulation and carrier adherence, ensuring efficient toner transfer and maintaining image quality by optimizing the surface roughness ratio and magnetic field strength between the rollers.
Implementation Method 1
a magnetic pole of the magnetic roller and a magnetic pole of the developing roller have magnetic polarities different from one another at the opposed position
Implementation Method 2
magnetic roller retaining the two-component developer to supply toners to the developing roller
Implementation Method 3
a surface roughness of the magnetic roller is greater than a surface roughness of the developing roller
Data Source
AI summary
A developing device uses a two-component developer including at least carriers and toners. The toners are supplied to an image bearing member bearing an electrostatic latent image so that a toner image is developed from the electrostatic latent image. The developing device has a developing roller arranged to oppose the image bearing member; and a magnetic roller arranged to oppose the developing roller. The magnetic roller retains the two-component developer to supply toners to the developing roller. The developing roller and the magnetic roller are rotationally driven in directions to be opposite from one another at an opposed position, and a magnetic pole of the magnetic roller and a magnetic pole of the developing roller have magnetic polarities different from one another at the opposed position. A surface roughness of the magnetic roller is greater than a surface roughness of the developing roller.