Developing Roller and Toner Composition for Stable Injection Charging
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Solution Overview
Problem
Existing developing systems using injection charging processes for toner face issues with charge leakage and retention, leading to adverse effects like fogging and toner scattering, particularly in long-term use, due to insufficient charge injectability and retention properties.
Innovation Solution
A developing apparatus with a toner carrying member and charging member, utilizing a developing roller with a conductive substrate and resin layer, combined with specific fine particles A and B, and a corona discharger configuration to achieve stable charge injection and retention, suppressing charge leakage and excessive charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If injection charging process is used to improve charge injection capability, then charge injection efficiency is improved, but charge retention deteriorates due to conductive path formation
Solution Approach 1:
The toner surface is equipped with conductive fine particles (charge injection portion) at specific locations to enable charge injection, while the bulk toner material remains insulating to prevent charge leakage. This local differentiation allows charge injection at contact points without creating conductive paths throughout the entire toner structure.
Solution Approach 2:
Conductive fine particles serve as intermediary elements between the charging member and the toner core. These particles enable charge transfer at the interface while the insulating binder resin prevents charge propagation into the toner bulk, thus mediating between charge injection requirements and charge retention needs.
2Productivity
If large amount of conductive external additive is added to improve charge injectability, then charge injection capability is improved, but charge leakage increases leading to fogging and toner scattering
Solution Approach 1:
Conductive fine particles are distributed only on the toner surface rather than uniformly throughout the toner bulk. This localized conductivity enables charge injection at the surface while preventing conductive path formation in the interior, thus avoiding charge leakage and its harmful effects.
Solution Approach 2:
The toner is constructed as a composite material combining conductive fine particles (for charge injection) with insulating binder resin (for charge retention). This composite structure integrates both conductive and insulating properties within a single toner particle, resolving the contradiction between charge injectability and charge leakage prevention.
3Productivity
If toner is used for long period, then productivity is maintained, but toner deformation occurs reducing rolling capability and charging performance
Solution Approach 1:
The toner particle structure with conductive fine particles on the surface and insulating binder resin in the bulk provides a flexible yet stable configuration. This structure maintains toner integrity and rolling capability over time, ensuring consistent charging performance during long-term operation.
Solution Approach 2:
The composite structure of conductive fine particles embedded in insulating binder resin provides both mechanical stability and electrical functionality. This composite material maintains its structural integrity and charging properties over extended use, preventing the performance degradation that occurs with conventional toner formulations.
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 ensures stable and efficient charge injection and retention, reducing fogging and toner scattering, even under varying environmental conditions and during high-speed processes.
Implementation Method 1
a corona discharger having a grid portion of which a width is 3.0 mm is arranged such that a distance between the grid portion and the outer surface of the developing roller is 1.0 mm
Implementation Method 2
triboelectric charging using contact of the toner regulating member and the developing roller with the toner
Data Source
AI summary
A developing apparatus including: a toner having a toner particle and an external additive; a toner carrying member used for carrying the toner; and a charging member used for injecting charge into the toner, in which the external additive includes a fine particle A and a fine particle B, the fine particle A is at least one fine particle selected from a group consisting of a silica fine particle and a silicone fine particle, the fine particle B is a specific conductive fine particle, the toner carrying member is a developing roller having: a substrate having an outer surface having conductivity; and a resin layer on the outer surface of the substrate, and impedance of the outer surface of the developing roller and a maximum value of electric potential of the outer surface are in specific ranges.