Developing Roller with Insulating Domain Protrusions for Toner Conveyance
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Solution Overview
Problem
Existing developing rollers in electrophotographic image forming apparatuses, particularly those with dielectric portions, face challenges in maintaining high-quality image formation, especially in low-temperature and low-humidity environments, due to uneven toner distribution and reduced toner conveying ability.
Innovation Solution
A developing roller with an electro-conductive elastic layer and insulating domains, featuring protrusions and specific surface potential characteristics, is designed to enhance toner conveying and uniformity, ensuring stable image formation by optimizing the surface potential and contact area ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a developing roller with dielectric portions is used to improve toner conveying ability, then toner conveying performance is improved, but image quality deteriorates due to uneven toner distribution and roughness
Solution Approach 1:
The developing roller surface is segmented into multiple functional domains: electro-conductive domains for toner conveying and electrical insulating domains for image quality control. This segmentation allows different regions to perform different functions optimally, resolving the contradiction between toner conveying ability and image uniformity.
Solution Approach 2:
Different regions of the developing roller are assigned different material properties and functions. The electro-conductive portions provide toner conveying capability while the insulating portions ensure uniform image formation. This local differentiation of properties allows simultaneous optimization of both toner conveying and image quality.
2Productivity
If the surface potential of the developing roller is increased to improve toner conveying, then toner conveying performance is improved, but image roughness increases
Solution Approach 1:
The roller surface is divided into electro-conductive and insulating domains with different potential characteristics. The electro-conductive domains maintain higher potentials for toner conveying while the insulating domains provide potential gradients that prevent image roughness, allowing both requirements to be satisfied simultaneously.
Solution Approach 2:
The surface potential distribution is carefully controlled and optimized across different domains. By adjusting the potential parameters in specific ranges (10-100V for electro-conductive domains, 2-5V for insulating domains), the system achieves optimal toner conveying while minimizing image roughness.
3Manufacturing precision
If the contact area between the developing roller and photosensitive member is increased to improve image quality, then image uniformity is improved, but toner conveying ability decreases
Solution Approach 1:
The contact interface is segmented into regions with different functional characteristics. The electro-conductive domains provide strong contact for toner transferring while the insulating domains provide controlled contact for image uniformity. This segmentation allows optimization of both toner conveying and image quality without compromise.
Solution Approach 2:
Different regions of the contact interface have different material properties and contact characteristics. The electro-conductive portions provide high contact area ratios (0.5-10.0%) for effective toner conveying while the insulating portions ensure uniform potential distribution for image quality, achieving both requirements locally.
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 achieves excellent toner conveying performance and suppresses image roughness and uneven development, maintaining high-quality electrophotographic image formation even in challenging environmental conditions.
Implementation Method 1
a surface potential of the developing roller at the domains is 10 V or more and 100 V or less corresponding to a completion of discharge
Implementation Method 2
toner can be electrically adsorbed onto the charged dielectric portion to convey the toner
Implementation Method 3
the charging of the surface of the developing roller being conducted with a discharge wire which is disposed substantially parallel to the longitudinal direction of the developing roller and so that the discharge wire is apart from the surface of the developing roller by 1 mm, by applying a direct-current voltage of 8 kV between the developing roller and the discharge wire
Implementation Method 4
an electro-conductive elastic layer on the substrate
Data Source
AI summary
It is directed to providing a developing roller capable of forming a high-quality electrophotographic image. The developing roller includes a substrate, an electro-conductive elastic layer on the substrate, and a plurality of electrical insulating domains on the electro-conductive elastic layer. The developing roller has a length L of 200 mm or more in a longitudinal direction orthogonal to the circumferential direction thereof. The surface of the developing roller includes the surfaces of the domains and an exposed portion of the electro-conductive elastic layer, the exposed portion being uncovered with the domains. The developing roller has protrusions on the surface thereof, the protrusion being formed by the domains. The electro-conductive elastic layer has a plurality of protrusions at the exposed portion. The developing roller has an Asker C hardness of 50 degrees or more and 90 degrees or less.