Charging Member Surface Layer for DC Contact Charging
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Solution Overview
Problem
The DC contact charging method for electrophotographic apparatuses suffers from issues with charge uniformity, contamination, and uneven electrical resistance, leading to overcharging or poor charging, especially in high-temperature and high-humidity environments due to toner and additive adherence on the charging member.
Innovation Solution
A charging member with a conductive elastic layer and a surface layer containing polysiloxane with fluoroalkyl and oxyalkylene groups is developed, which inhibits toner and additive adherence, ensuring stable charging and image output over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If DC contact charging method is used, then apparatus size and cost are reduced, but charge uniformity deteriorates and contamination increases
Solution Approach 1:
The charging member employs a multi-layer structure where each layer has different properties: the conductive elastic layer provides charging function while the surface layer with polysiloxane containing fluoroalkyl and oxyalkylene groups provides anti-adhesion properties. This local differentiation of material properties allows the charging surface to maintain both charging effectiveness and resistance to toner/adhesive accumulation, resolving the contradiction between simplified DC charging and reliable charge uniformity.
Solution Approach 2:
The charging member uses a composite structure combining conductive elastic material with a surface coating of polysiloxane containing fluoroalkyl and oxyalkylene groups. This composite material approach creates a surface that simultaneously achieves good electrical conductivity for charging and low surface energy for preventing toner and adhesive adherence, thereby maintaining charge uniformity without requiring complex AC+DC charging apparatus.
2Device complexity
If DC contact charging method is used, then apparatus size and cost are reduced, but contamination increases
Solution Approach 1:
The charging member employs a multi-layer structure where each layer has different properties: the conductive elastic layer provides charging function while the surface layer with polysiloxane containing fluoroalkyl and oxyalkylene groups provides anti-adhesion properties. This local differentiation of material properties allows the charging surface to maintain both charging effectiveness and resistance to toner/adhesive accumulation, resolving the contradiction between simplified DC charging and reliable charge uniformity.
Solution Approach 2:
The charging member uses a composite structure combining conductive elastic material with a surface coating of polysiloxane containing fluoroalkyl and oxyalkylene groups. This composite material approach creates a surface that simultaneously achieves good electrical conductivity for charging and low surface energy for preventing toner and adhesive adherence, thereby maintaining charge uniformity without requiring complex AC+DC charging apparatus.
3Object-affected harmful factors
If conventional surface layer is used, then low molecular weight component bleeding is inhibited, but toner and additive adherence increases over time
Solution Approach 1:
The charging member uses a composite structure combining conductive elastic material with a surface coating of polysiloxane containing fluoroalkyl and oxyalkylene groups. This composite material approach creates a surface that simultaneously achieves good electrical conductivity for charging and low surface energy for preventing toner and adhesive adherence, thereby maintaining charge uniformity without requiring complex AC+DC charging apparatus.
Solution Approach 2:
The invention changes the chemical composition parameters of the surface layer by incorporating polysiloxane with specific functional groups (fluoroalkyl and oxyalkylene groups). This parameter change results in a surface with appropriately low surface free energy that prevents toner and adhesive accumulation, while the layer thickness is controlled at 1 μm or less to maintain charging performance.
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 proposed charging member effectively prevents toner and additive adherence, maintaining charge uniformity and image stability even under repeated use in DC contact charging methods, enhancing the reliability of the electrophotographic apparatus.
Implementation Method 1
the surface layer contains a polysiloxane having a fluoroalkyl group and an oxyalkylene group... the surface free energy of the charging member is 35 dyn/cm or less... it is hard for a toner, an additive for use in the toner, or the like to adhere to the surface
Implementation Method 2
a voltage is applied to a charging member situated to be in contact with the electrophotographic photosensitive member to cause a very low level of electrical discharge near a contact area between the charging member and the electrophotographic photosensitive member, whereby the surface of the electrophotographic photosensitive member is charged
Data Source
AI summary
A charging member is provided in which a toner, an additive for use in the toner, or the like is hard to adhere to the surface even under repeated use for a long time, and hence the charging and image output are made stable for a long time even if the charging member is used in the DC contact charging method. Also provided are a process cartridge and an electrophotographic apparatus having the charging member. The charging member includes a support, a conductive elastic layer formed on the support, and a surface layer formed on the conductive elastic layer, characterized in that the surface layer contains a polysiloxane having a fluoroalkyl group and an oxyalkylene group, and a process cartridge and an electrophotographic apparatus having the charging member.