Electrophotographic Developing Member with Insulating and Conductive Regions
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Solution Overview
Problem
Existing electrophotographic developing members fail to consistently produce high-density images initially after a standby state, leading to insufficient toner adsorption and uneven image density in electrophotographic images.
Innovation Solution
An electrophotographic developing member with a porous electroconductive elastic layer and an electroconductive solid layer, featuring an electrical insulating surface region and an electroconductive surface region, where the electrical insulating portion is charged through friction with the toner regulating member, promoting uniform toner conveyance and pressure distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional developing member is used, then the device structure is simple, but the initial image density is insufficient and image quality is unstable
Solution Approach 1:
The outer surface of the developing member is divided into two distinct regions: an electrical insulating region and an electroconductive region. This segmentation allows different surface areas to perform different functions - the insulating region generates strong electric fields for rapid toner conveyance to ensure high initial image density, while the electroconductive region provides stable baseline performance. The segmentation resolves the contradiction by enabling high initial image quality without requiring complete restructuring of the entire developing member.
Solution Approach 2:
Different regions of the developing member surface are given different electrical properties - the electrical insulating portion has high resistance to generate strong local electric fields for rapid toner conveyance, while the electroconductive portion has low resistance for stable operation. This local differentiation of properties allows the system to achieve high initial image density in the insulating region while maintaining overall structural simplicity and operational stability through the electroconductive regions.
2Productivity
If the electrical insulating portion has high volume resistivity, then toner conveyance is rapid and initial image density is sufficient, but charge retention may be poor
Solution Approach 1:
The developing member surface is segmented into electrical insulating regions for rapid toner conveyance and electroconductive regions for charge retention. The insulating regions with high volume resistivity (≥1.0×10^13 Ω·cm) rapidly convey toner to ensure sufficient initial image density, while the electroconductive regions provide stable charge holding. This spatial segmentation resolves the contradiction between rapid conveyance and charge retention by assigning each function to appropriate regions.
Solution Approach 2:
The volume resistivity of the electrical insulating portion is specifically controlled to be 1.0×10^13 Ω·cm or higher, which optimizes the electric field strength for rapid toner conveyance while the adjacent electroconductive portions maintain charge stability. This parameter optimization in the insulating region, combined with the contrasting electroconductive regions, resolves the contradiction between conveyance speed and charge retention.
3Use of energy by stationary object
If the developing member is in standby state for extended period, then energy consumption is reduced, but image density becomes uneven upon initial print
Solution Approach 1:
The electrical insulating regions are pre-configured with high volume resistivity to generate strong electric fields that rapidly convey toner during the first print operation after standby. This preliminary preparation of the insulating regions ensures that even after extended standby periods with minimal energy consumption, the initial image maintains sufficient density and uniformity when printing resumes.
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 ensures a sufficient initial image density and maintains consistent image quality by rapidly charging the electrical insulating portion, preventing black spots and density variations between initial and subsequent prints.
Implementation Method 1
the electrical insulating portion is charged through friction with the toner regulating member
Implementation Method 2
rapidly charging the electrical insulating portion, preventing black spots and density variations
Data Source
Figure 1A~1D
Figure 2
Figure 3
AI summary
Provided is an electrophotographic developing member capable of sufficiently increasing a density of an image initially output from a standby state. The developing member includes: a substrate; a porous electro conductive elastic layer on the substrate; and an electroconductive solid layer on the electroconductive elastic layer, in which an outer surface of the developing member includes a first region having an electrical insulating surface and a second region having an electroconductive surface, the first region and the second region are arranged to be adjacent to each other, and the first region is constituted by an electrical insulating portion disposed on an outer surface of the electroconductive solid layer.