Developing Roller Surface Domain Design for Toner Conveyance
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Solution Overview
Problem
Existing developing rollers for electrophotography have insufficient toner conveyance ability, leading to roughness in electrophotographic images due to inadequate potential difference between insulating and conductive regions on the roller surface.
Innovation Solution
A developing roller with an electroconductive substrate and layer that retains resin particles, creating electrically insulating domains and a conductive matrix on its surface, with specific domain sizes and inter-domain distances to enhance the potential gradient and toner conveyance, achieved through careful particle size adjustment and surface treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulating particles are dispersed in the electroconductive material to form a surface layer, then the number of minute closed electric fields (microfields) increases and toner conveyance ability is enhanced, but the developer conveyance ability remains insufficient causing image roughness
Solution Approach 1:
The invention creates regions with different electrical conductivity properties on the developing roller surface. Specifically, it forms insulating domains (with insulating particles) and conductive domains (without insulating particles) in a distributed pattern. This local differentiation of electrical properties generates microfields that enhance toner conveyance while maintaining sufficient developer flow, thereby resolving the contradiction between toner conveyance ability and image quality.
Solution Approach 2:
The developing roller surface is segmented into multiple functional domains: insulating domains containing insulating particles and conductive domains without them. This segmentation creates a heterogeneous surface structure that generates numerous microfields. The segmented structure allows simultaneous achievement of enhanced toner conveyance in insulating domains and sufficient developer conveyance in conductive domains, preventing image roughness.
2Quantity of substance
If the developing roller surface has insufficient potential difference between insulating and conductive regions, then developer flow is maintained, but toner conveyance ability is insufficient leading to image roughness
Solution Approach 1:
The invention optimizes several key parameters: the size of insulating particles (0.1-10 μm), the concentration of insulating particles in the surface layer (1-50 wt%), and the thickness of the surface layer (1-10 μm). These parameter adjustments create an optimal balance where sufficient potential difference is generated between insulating and conductive domains to enhance toner conveyance, while maintaining adequate developer flow to prevent image roughness.
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 enhanced potential gradient significantly improves toner conveyance ability, resulting in higher-quality electrophotographic images by ensuring a stable and sufficient amount of toner is retained and conveyed on the roller surface.
Implementation Method 1
the outer surface of the developing roller is constituted by electrically insulating domains, and an electroconductive matrix, each of the electrically insulating domains being constituted by the part of each of the resin particles exposed on the outer surface of the developing roller
Implementation Method 2
by applying a direct voltage of −5 kV between the substrate and the discharge wire... a potential at each point of intersection between those straight lines with an electrical force microscope is measured
Data Source
AI summary
Provided is a developing roller comprising an electroconductive substrate and an electroconductive layer thereon, the electroconductive layer retaining resin particles so that at least a part of each of the resin particles is exposed on an outer surface of the developing roller; the outer surface of the developing roller constituted by electrically insulating domains and an electroconductive matrix, assuming that a square region 200-μm in a side is put on the outer surface of the developing roller, the square region including the domains, among the domains in the square region at least two of them satisfying specific condition, and assuming that the outer surface of the developing roller is charged, and creating a potential map of the charged outer surface of the developing member, the two domains satisfying the specific condition being ascertained in the potential map.