Developer Carrier Resin Coat Layer for Toner Charge Control
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Solution Overview
Problem
Existing developer carrying members in electrophotography face challenges with charge uniformity and stability of toners, leading to issues like charge-up, image density variations, and faulty images due to non-uniform toner charging and adhesion, especially in varying environmental conditions.
Innovation Solution
A developer carrying member with a resin coat layer containing graphitized carbon black, which has a specific lattice spacing and particle size range, providing improved lubricity and wear resistance to prevent toner charge-up and ensure uniform charging, even in long-term use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a toner with small particle diameter and spherical shape is used to improve fluidity and reduce waste toner, then fluidity is improved, but uniform coating on the developing sleeve becomes difficult
Solution Approach 1:
The patent applies local quality by creating a specific surface structure on the developing sleeve at the contact portion with the toner. The outer layer contains voids with specific volume ratios (5-50%) and controlled pore sizes (0.1-10 μm), providing localized properties that differ from the inner layer. This local modification enables the surface to accommodate small spherical toner particles while maintaining uniform coating, resolving the contradiction between improved fluidity and coating uniformity.
2Productivity
If the developing sleeve is repeatedly rotated to maintain operation, then productivity is maintained, but charge-up phenomenon occurs causing toner to adhere strongly to the sleeve surface
Solution Approach 1:
The patent converts the harmful charge-up phenomenon into a beneficial effect by designing the outer layer with conductive carbon particles dispersed in the resin matrix. The voids in the outer layer facilitate charge dissipation, while the carbon particles provide controlled conductivity. This transforms the previously harmful accumulation of static charge into a beneficial mechanism where charge is evenly distributed and dissipated, preventing toner adhesion issues during continuous operation.
Solution Approach 2:
The patent employs composite materials by creating a multi-layer structure with distinct compositions. The inner layer uses a base resin (polycarbonate, polyester, or acrylic) providing mechanical strength, while the outer layer combines the same or different resin with conductive carbon particles (acetylene black, ketjen black, or graphite) dispersed at 1-50 wt%. This composite structure provides both mechanical durability for continuous rotation and electrical conductivity for charge management, resolving the contradiction between productivity and charge uniformity.
3Manufacturing precision
If toner control power is enhanced by using a developer layer thickness control member to uniformly coat small spherical toner, then coating uniformity is improved, but toner may melt-adhere to the developing sleeve in low-temperature and low-humidity environments
Solution Approach 1:
The patent applies local quality by creating a surface layer with specific thermal and friction properties. The outer layer contains voids (5-50% volume ratio) that reduce thermal contact between the toner and the developing sleeve, and the carbon particle dispersion provides controlled friction. This localized modification at the toner-contact surface prevents melt adhesion while maintaining coating uniformity, resolving the contradiction between these two parameters in low-temperature environments.
4Reliability
If a resin coat layer with dispersed solid lubricant is used to prevent charge-up, then charge uniformity is improved, but the resin coat layer surface may become non-uniform causing wear and particle liberation
Solution Approach 1:
The patent applies parameter changes by precisely controlling the void volume ratio (5-50%) and pore size (0.1-10 μm) in the outer layer, and the carbon particle concentration (1-50 wt%). These parameter optimizations ensure that the voids are sufficient to prevent charge-up but not so large as to cause surface non-uniformity. The controlled parameters maintain surface integrity while providing the necessary charge uniformity, resolving the contradiction between these two properties.
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 prevents toner charge-up and melt-adhesion, maintaining uniform coating and high-grade image quality across different environments, reducing issues like image density decrease, non-uniformity, and vertical streaks.
Implementation Method 1
the resin coat layer contains at least a binder resin and a carbon black... providing improved lubricity and wear resistance to prevent toner charge-up
Implementation Method 2
providing improved lubricity and wear resistance to prevent toner charge-up and ensure uniform charging, even in long-term use
Data Source
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AI summary
A developer carrying member is provided which, even in continuous copying over a long term and also even under different environmental conditions, do not cause any charge-up of toner, and prevent the toner from melt-adherent to the developer carrying member surface and developer layer thickness control member surface to maintain the state of uniform coating of a developer having a toner and to make the toner uniformly and quickly triboelectrically charged, so as to obtain high-grade images free of any image density decrease, image density non-uniformity, sleeve ghosts, fog and vertical streaks during running service. Provided are a developer carrying member having a substrate and a resin coat layer on the surface of the substrate, which resin coat layer contains at least a binder resin and a carbon black, where the graphite (002) plane obtained from X-ray diffraction of the carbon black has a lattice spacing of from 0.3370 nm or more to 0.3450 nm or less; and a developing assembly having such a developer carrying member.