Developer Carrier Surface Layer for Talc-Resistant Toner Charging
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the use of talc-rich sheets often results in fogging due to talc particles being negatively charged and electrostatically attached to the developer carrying member, reducing the toner's charge applying ability and leading to suboptimal image quality.
Innovation Solution
A developer carrying member with a specific surface layer configuration, including a thickness of 1.0 µm to 100.0 µm, Martens hardness of 50.0 N/mm² to 100.0 N/mm², Asker C hardness of 75° to 90°, and a work function of 5.6 eV to 6.0 eV, is developed to prevent talc attachment and maintain effective toner charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a surface layer containing resin with quaternary ammonium salt group or tertiary amine group is used to increase electric charge applying ability, then toner charging is improved, but talc particles are negatively charged and electrostatically attached to the developer carrying member causing fogging
Solution Approach 1:
The patent changes the physical and chemical parameters of the surface layer, specifically setting the thickness to 1.0 µm to 100.0 µm and Martens hardness to 50.0 N/mm² to 100.0 N/mm². These parameter adjustments optimize the balance between maintaining toner charging ability and preventing talc particle attachment, thereby reducing fogging while preserving image quality.
Solution Approach 2:
The surface layer is constructed as a composite material containing resin with specific functional groups (quaternary ammonium salt or tertiary amine) combined with controlled thickness and hardness properties. This composite structure enables the surface to simultaneously provide electrostatic charging functionality while resisting talc particle adhesion, resolving the contradiction between charging ability and fogging prevention.
2Object-affected harmful factors
If the surface layer thickness is increased to prevent talc attachment, then fogging is reduced, but the electric charge applying ability may be compromised
Solution Approach 1:
The patent identifies and optimizes critical parameters including surface layer thickness (1.0 µm to 100.0 µm) and Martens hardness (50.0 N/mm² to 100.0 N/mm²). By precisely controlling these parameters, the surface layer achieves optimal performance in preventing talc attachment while maintaining sufficient electric charge applying ability for effective toner charging.
Solution Approach 2:
The surface layer acts as an intermediary between the toner and the underlying structure, with its specific thickness and hardness properties mediating the interaction between electrostatic charging and talc particle prevention. This intermediary layer provides a balanced interface that enables both functions to coexist effectively.
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 effectively suppresses talc-derived fogging while ensuring sufficient toner charging, resulting in stable and high-definition electrophotographic images across various sheets.
Implementation Method 1
talc particles being negatively charged and electrostatically attached to the developer carrying member
Implementation Method 2
a work function of 5.6 eV to 6.0 eV
Implementation Method 3
Martens hardness at an indentation depth of 0.1 μm that is measured by infiltrating a Vickers indenter in a thickness direction of the surface layer
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
Provided is a developer carrier which is capable of stably forming high-quality images even in cases where a recording paper containing much talc is used. This developer carrier comprises a conductive substrate and a surface layer that is arranged on the substrate and contains a resin. The surface layer has a thickness of from 1.0 µm to 100.0 µm (inclusive); the Martens hardness at an indentation depth of 0.1 µm as determined by pressing a Vickers indenter into the surface layer from the outer surface in the thickness direction is from 50.0 N/mm2 to 100.0 N/mm2 (inclusive); the Asker C hardness as determined from the outer surface of the surface layer is from 75° to 90° (inclusive); and the value of the work function of the outer surface of the surface layer is from 5.6 eV to 6.0 eV (inclusive).