Electrophotographic Charging Member with Crosslinked Rubber Protrusions
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Solution Overview
Problem
In electrophotographic image forming apparatuses using a contact charging method, the cleanerless system faces challenges with excessive adhesion of transfer residual toner on the charging member, leading to contamination and reduced image quality over time.
Innovation Solution
A charging member with an electro-conductive support and an electro-conductive elastic layer containing crosslinked rubber particles, where the crosslinked rubber particles have a circle-equivalent diameter of 10 μm to 50 μm and are chemically bonded with an acrylic or styrene acrylic resin, creating protrusions on the surface that reduce toner adhesion and maintain rolling properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a contact charging method is adopted in a cleanerless system, then the system can be simplified and waste eliminated, but transfer residual toner adheres excessively to the charging member surface
Solution Approach 1:
The charging member surface is modified with fine particles (0.1-10 μm) dispersed in the electro-conductive elastic layer, creating localized regions with different surface properties. These fine particles reduce the surface energy and create micro-roughness that prevents toner adhesion, while maintaining the overall contact charging function. This local modification allows the charging member to resist toner adhesion without requiring additional cleaning mechanisms.
Solution Approach 2:
The charging member uses a composite structure combining an electro-conductive support with an electro-conductive elastic layer containing both rubber particles (10-100 μm) and fine particles (0.1-10 μm). This composite material approach integrates multiple functions: the rubber particles provide elasticity and contact pressure, the fine particles reduce toner adhesion, and the electro-conductive components enable charging. The combination resolves the contradiction by achieving both simplified system operation and reduced toner contamination.
2Object-generated harmful factors
If fine particles are added to the charging member surface to reduce adhesion, then toner contamination is reduced, but the surface roughness increases
Solution Approach 1:
The invention optimizes the size parameters of the fine particles within a specific range (0.1-10 μm) to achieve the right balance. Particles that are too large would create excessive roughness and affect contact uniformity, while particles that are too small would not effectively reduce adhesion. By controlling the particle size within this range and limiting the content to 1-50 mass%, the surface maintains sufficient smoothness for good contact while having enough micro-roughness to prevent toner adhesion.
Solution Approach 2:
The fine particles are dispersed throughout the electro-conductive elastic layer rather than forming a continuous surface layer. This creates localized regions of reduced surface energy and micro-roughness at the particle sites, while the overall surface maintains the smoothness needed for uniform contact charging. The local modification approach allows adhesion reduction without globally increasing surface roughness.
3Stability of the object's composition
If the charging member surface is made smoother to maintain good contact, then contact uniformity improves, but toner adhesion increases
Solution Approach 1:
The charging member employs a composite elastic layer containing rubber particles for elasticity, fine particles for adhesion reduction, and electro-conductive materials for charging function. This composite structure resolves the contradiction by combining materials with complementary properties: the rubber matrix provides smooth contact surfaces, while the dispersed fine particles create local anti-adhesion sites. The result is a surface that maintains good contact uniformity overall while having localized regions that prevent toner adhesion.
Solution Approach 2:
Rather than making the entire surface rough to prevent adhesion, the invention uses locally dispersed fine particles (0.1-10 μm) within the electro-conductive elastic layer. These particles create localized micro-roughness and reduce surface energy only at specific sites, while the majority of the surface remains smooth for uniform contact. This local quality approach maintains contact uniformity while providing sufficient anti-adhesion characteristics.
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 the adhesion of transfer residual toner and external additives, ensuring stable and high-quality image formation over a long period, even under high-speed conditions with small particle diameter toner, by reducing contact area and promoting tribocharging and surface durability.
Implementation Method 1
a fine particle is contained in a surface layer to control surface roughness and reduce adhesion
Implementation Method 2
the adhesion of contamination such as transfer residual toner is more suppressed
Implementation Method 3
promoting tribocharging and surface durability
Data Source
AI summary
An electrophotographic charging member in which the adhesion of contamination is more suppressed is provided. The electrophotographic charging member includes an electro-conductive support and an electro-conductive elastic layer on the electro-conductive support, the electro-conductive elastic layer includes 10% by mass or more and 50% by mass or less of an aggregate of crosslinked rubber particles, the aggregate of the crosslinked rubber particles has a circle-equivalent diameter of 10 μm or more and 50 μm or less, the crosslinked rubber particles have one of an acrylic resin and a styrene acrylic resin chemically bonded to a surface thereof, the charging member has a protrusion derived from the aggregate of the crosslinked rubber particles on a surface thereof, and the protrusion has an average height of 50 nm or more and 200 nm or less.