Charging Roller Surface Roughness and Fluorine Coating for Toner Granularity
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Solution Overview
Problem
Conventional electrophotographic image forming apparatuses face challenges in maintaining fine granularity and preventing depletion of the electrophotographic photosensitive body, especially during long-period printing, due to surface roughness issues with charging rollers and inadequate pollution prevention methods.
Innovation Solution
An electrophotographic image forming apparatus with a charging roller having a surface protective layer containing inorganic microparticles with a fluorine compound and a binder resin, maintaining a maximum height roughness of ≤0.5 μm, which enhances electroconductivity, light permeability, and stability, while preventing slip-through and torque reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a charging roller with maximum height roughness Rz of several micrometers is used, then pollution of the charging roller during printing is suppressed, but granularity of the formed toner image deteriorates and depletion amount of the photosensitive body increases
Solution Approach 1:
The invention changes the surface roughness parameter of the charging roller from conventional several micrometers to 0.5 μm or less, and introduces fluorine-containing substances to modify the surface properties. This parameter change enables simultaneous achievement of fine granularity and reduced photosensitive body depletion while maintaining pollution suppression.
2Manufacturing precision
If Vpp and frequency wave number are preset to be high to improve granularity in contact electrification, then granularity is improved, but depletion of the photosensitive body is further accelerated
Solution Approach 1:
The invention changes the charging method from conventional contact electrification with high Vpp to a charging process using a charging roller with Rz≤0.5 μm and fluorine-containing surface treatment. This allows achieving fine granularity without accelerating photosensitive body depletion.
Solution Approach 2:
The invention uses a composite surface treatment on the charging roller combining fluorine-containing substances with the roller surface, creating a composite structure that enables gentle charging while maintaining image quality and reducing material depletion.
3Manufacturing precision
If a roughnessless charging roller with Rz≤0.5 μm is used, then fine granularity is obtained and photosensitive body depletion is suppressed, but slip-through of toner from cleaning blade occurs and granularity and chargeability deteriorate over time
Solution Approach 1:
The invention applies fluorine-containing substances to the surface of the photosensitive body in advance before printing begins. This preliminary action creates a protective layer that prevents toner slip-through during the charging process, thereby maintaining chargeability and preventing granularity deterioration over extended printing periods.
Solution Approach 2:
The invention uses a composite surface treatment on the photosensitive body incorporating fluorine-containing substances. This composite structure provides both the smooth surface needed for fine granularity and the fluorine-based protection against toner adhesion, solving the long-term reliability issue.
4Reliability
If fluorine atoms are added to suppress slip-through, then slip-through is suppressed, but fluorine atoms segregate in the vicinity of the surface and slip-through cannot be suppressed over a long period
Solution Approach 1:
The invention uses a composite surface treatment on the photosensitive body that incorporates fluorine-containing substances in a stable configuration. This composite structure prevents fluorine atom segregation and maintains slip-through suppression effectiveness over extended printing periods.
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 maintains fine granularity and suppresses photosensitive body depletion over long printing periods by ensuring homogeneous dispersion of inorganic microparticles and reducing torque, thereby preventing surface pollution and improving cleaning properties.
Implementation Method 1
a charging roller for causing contact electrification on the surface of the electrophotographic photosensitive body
Data Source
AI summary
An electrophotographic image forming apparatus includes: an electrophotographic photosensitive body including an electroconductive substrate, and a charge generating layer, a charge transfer layer and a surface protective layer laminated on the substrate in this order, and a charging roller for causing contact electrification on the surface of the electrophotographic photosensitive body, wherein at least the surface protective layer contains inorganic microparticles having a fluorine compound on the surfaces and a binder resin, and the surface of the charging roller has a maximum height roughness Rz≤0.5 μm.