Developing Roller Surface Layer for Toner Contamination Control
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Solution Overview
Problem
Existing developing rollers fail to adequately suppress contamination on the outer surface of photosensitive members when abutting pressure is reduced, leading to decreased image quality due to residual toner and external additives, resulting in decreased image density and white spots.
Innovation Solution
A developing roller with a surface layer comprising a matrix of polyurethane as a binder and resin particles, featuring specific elastic moduli and surface protrusions to effectively scrape off external additives and prevent toner fusion bonding, while maintaining sufficient hardness to resist wear and maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the abutting pressure of the cleaning blade on the photosensitive member is reduced to save energy, then energy consumption is reduced, but residual toner is not sufficiently removed and adheres to the photosensitive member, lowering image quality
Solution Approach 1:
The patent changes the physical parameters of the developing roller surface layer by controlling the elastic modulus of the matrix (10-100 MPa at depth ≥1.0 μm) and incorporating resin particles with specific elastic moduli (E1: 100-2000 MPa, E2: 2-50 MPa). These parameter changes enable the surface layer to effectively remove external additives and suppress toner fusion bonding even at reduced abutting pressures, thereby resolving the contradiction between energy saving and contamination prevention
Solution Approach 2:
The patent employs a composite material structure consisting of a matrix containing polyurethane as a binder with dispersed resin particles having different elastic moduli. This composite structure combines the flexibility of the matrix with the hardness of the resin particles, creating a surface layer that can simultaneously reduce stress on toners and effectively scrape off external additives, thus preventing contamination while allowing reduced abutting pressure
2Object-generated harmful factors
If the abutting pressure is reduced to suppress fusion bonding of toners, then toner fusion bonding is reduced, but residual toner and external additives adhere to the photosensitive member, decreasing image density and quality
Solution Approach 1:
The patent applies local quality by creating a surface layer with specific spatial distribution of resin particles (first resin particles with E1=100-2000 MPa and second resin particles with E2=2-50 MPa) within a matrix having controlled elastic modulus (10-100 MPa at depth ≥1.0 μm). This local structural differentiation enables the surface layer to provide both stress reduction and effective cleaning functions at the toner-photosensitive member interface, resolving the contradiction between suppressing fusion bonding and preventing contamination
Solution Approach 2:
The patent changes the mechanical parameters of the developing roller surface layer by precisely controlling the elastic modulus distribution: the matrix has Eb=10-100 MPa at depth ≥1.0 μm, first resin particles have E1=100-2000 MPa, and second resin particles have E2=2-50 MPa. These parameter changes enable the surface layer to effectively remove external additives while suppressing toner fusion bonding, thereby improving both image quality and density
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 developed roller effectively suppresses contamination and maintains image quality by efficiently removing external additives and preventing toner fusion bonding, even at reduced abutting pressures, thereby ensuring stable and high-quality electrophotographic images.
Implementation Method 1
the matrix having an elastic modulus Eb of 10 to 100 MPa when measured at a region in a cross section in a thickness direction of the surface layer
Implementation Method 2
a high frictional force is generated by rubbing with the photosensitive member
Implementation Method 3
the outer surface of the surface layer having a first protrusion and a second protrusion... the first protrusion being formed by the first resin particle, the second protrusion being formed by the second resin particle
Implementation Method 4
an electro-conductive substrate; an electro-conductive elastic layer on the electro-conductive substrate
Implementation Method 5
The coated toner is conveyed to an abutting portion between the photosensitive member on which the above electrostatic latent image is formed and the developing roller, by a rotation of the developing roller
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
The present invention provides a developing roller that suppresses contamination of the surface of a photosensitive member and also obtains a high-quality image. The developing roller includes an electro-conductive substrate, an electro-conductive elastic layer and a surface layer which are stacked in this order, wherein the surface layer has resin particles that are dispersed in a polyurethane matrix, an outer surface of the surface layer has a first protrusion originating in first resin particle and a second protrusion originating in second resin particle, wherein the first resin particle contains polyurethane, an elastic modulus E1 of the first resin particle is 100 to 2000 MPa, an elastic modulus E2 of the second resin particle is 2 to 50 MPa, a maximum height roughness Rz of the outer surface is 6 to 18 µm, and a peak vertex density Spd is 5.0×103 to 5.0×104(1/mm2).