Electrophotographic Developing Roller with Insulating Domains
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Solution Overview
Problem
Existing electrophotographic developing rollers face challenges in achieving both high toner-conveying force and charge-providing performance, especially under high-temperature and high-humidity environments, leading to potential 'fogging' issues and non-uniform image formation.
Innovation Solution
A member for electrophotography featuring a substrate with an electro-conductive elastic layer and electrically insulating domains, where the electro-conductive elastic layer has a specific Martens hardness and exposure ratio, and the electrically insulating domains have controlled areas and heights, enhancing toner conveyance and triboelectric charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the diameter of the developing roller and developer-supplying roller is reduced to decrease apparatus size and energy consumption, then the apparatus size and energy consumption are reduced, but the toner layer formation becomes insufficient and image uniformity deteriorates
Solution Approach 1:
The developing roller surface is divided into two distinct regions: a dielectric portion with high electric resistance value for toner adsorption and conveyance, and a conductive portion with low electric resistance value for charge provision to the toner. This local differentiation allows each region to perform its specific function optimally, resolving the contradiction between energy efficiency and image quality.
Solution Approach 2:
The roller surface is segmented into functionally distinct dielectric and conductive portions, allowing independent optimization of toner conveyance and charging functions. This segmentation enables the roller to simultaneously achieve effective toner layer formation and adequate charge provision without requiring larger dimensions.
2Force
If a dielectric portion with high electric resistance value is arranged on the roller surface to improve toner-conveying force, then the toner-conveying force is improved, but the charge-providing performance for toner reduces and fogging occurs
Solution Approach 1:
The roller surface is divided into two distinct regions: a dielectric portion with high electric resistance value for toner adsorption and conveyance, and a conductive portion with low electric resistance value for charge provision to the toner. This local differentiation allows each region to perform its specific function optimally, resolving the contradiction between toner conveying force and charge-providing performance.
Solution Approach 2:
The roller surface is segmented into functionally distinct dielectric and conductive portions, allowing independent optimization of toner conveyance and charging functions. The dielectric portion provides strong toner adsorption while the conductive portion ensures adequate charge provision, eliminating fogging issues.
3Power
If the penetration amount of the member is reduced to decrease torque, then the torque is reduced, but the toner layer formation becomes insufficient and image uniformity deteriorates
Solution Approach 1:
The developing roller surface is divided into two distinct regions: a dielectric portion with high electric resistance value for toner adsorption and conveyance, and a conductive portion with low electric resistance value for charge provision to the toner. This local differentiation allows each region to perform its specific function optimally, resolving the contradiction between torque reduction and image quality.
Solution Approach 2:
The roller surface is segmented into functionally distinct dielectric and conductive portions, allowing independent optimization of toner conveyance and charging functions. This segmentation enables the roller to achieve effective toner layer formation and adequate charge provision without requiring larger penetration amounts or higher torque.
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
This configuration improves toner-conveying force and charge-providing performance, ensuring high-quality image formation under various environmental conditions while minimizing fogging and maintaining image uniformity.
Implementation Method 1
the electrostatic latent image is developed with the toner at a contact portion between the photosensitive member and the developing roller
Implementation Method 2
a dielectric portion having a high electric resistance value is arranged on the surface of the roller, and the charged dielectric portion is caused to electrically adsorb a toner
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Provided is a member for electrophotography (1) that can achieve both an improvement in toner-conveying force under high temperature and high humidity, and excellent charge-providing performance for a toner, at high levels. The member for electrophotography includes a substrate (2), an electro-conductive elastic layer (3) on the substrate, and a plurality of electrically insulating domains (4) formed in a partial region on the electro-conductive elastic layer. The electro-conductive elastic layer (3) has a Martens hardness of 0.10 N/mm2 or more and 3.00 N/mm2 or less. In the surface of the member for electrophotography (1), the exposure ratio of the electro-conductive elastic layer per the area of a square 300 µm on a side is 50% to 90%, and the average of the areas of the portions of the respective plurality of electrically insulating domains (4) to be brought into contact with the electro-conductive elastic layer is 300 µm2 or more and 10,000 µm2 or less.