Conductive End-Coated Developing Roller for Nonprinting Scumming
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Solution Overview
Problem
Electrophotographic devices experience scumming in nonprinting areas due to toner adherence caused by increased electrical resistance at the developing roller's end portions, resulting from insulating materials used in end portion treatments.
Innovation Solution
A developing roller with an elastic layer, a conductive coat layer, and end portion coat layers containing a conductive material, specifically an ionic conductive agent, to maintain a controlled resistance ratio and prevent toner adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an insulating coating liquid is used for end portion treatment of the developing roller, then wear resistance at the two axial end portions is improved, but the electrical resistance value increases causing toner to easily adhere and transfer to nonprinting areas
Solution Approach 1:
The patent applies different functional properties to different regions of the developing roller. The end portion coat layer contains a conductive material (0.01-5 wt%) to provide local conductivity at the axial ends, while the main body maintains its wear-resistant insulating coating. This local differentiation allows the end portions to prevent toner adherence without compromising the overall wear resistance of the roller.
Solution Approach 2:
The end portion coat layer is formed as a composite material combining the base coating material with conductive materials such as carbon black, graphite, or metal particles. This composite structure provides both the wear resistance of the base material and the electrical conductivity needed to prevent toner adhesion at the end portions.
2Strength
If the electrical resistance value at the end portion is increased by insulating coating, then wear resistance is improved, but the toner becomes overcharged and moves to nonprinting area
Solution Approach 1:
The patent introduces conductivity locally at the end portions through the end portion coat layer containing conductive materials, while maintaining the insulating properties of the main body coating. This localized conductivity control prevents toner overcharge at critical areas without sacrificing the wear resistance provided by the insulating coating elsewhere.
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 conductive material in the end portion coat layer suppresses electrical resistance increases, reducing toner adherence and preventing scumming in nonprinting areas while ensuring excellent wear resistance.
Implementation Method 1
the end portion coat layer contains a conductive material... the increase in the electrical resistance value is suppressed in the part adjacent to the end portion coat layer
Implementation Method 2
the conductive material is an ionic conductive agent... the toner is overcharged, and the overcharged toner moves to the nonprinting area
Data Source
AI summary
The purpose of the present invention is to provide a developing roller which is not prone to scumming in a nonprinting area. The solution is to provide a developing roller which has an elastic layer, a coat layer formed on the elastic layer, and end portion coat layers formed on outermost surfaces on two axial end portions, wherein the end portion coat layer contains a conductive material.