Developing Roller Electrostatic Capacitance Control for Banding Reduction
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Solution Overview
Problem
Banding in printed images occurs due to changes in the nip width between the developing roll and photoreceptor caused by distortion and stick slip, which are not effectively addressed by existing technologies.
Innovation Solution
A developing roller with a rubber elastomer layer and a coating layer formed from a binder and silicone rubber particles, where the binder is derived from a terminal hydroxyl group-containing prepolymer obtained by reacting an isocyanate compound, an isocyanurate modified product, and a reactive silicone oil, controlling the electrostatic capacitance between 4 to 20 nF to ensure stable toner transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the developing roller rotates at a higher speed than the photoreceptor to stably feed toner, then toner feeding stability is improved, but distortion and stick slip occur between the developing roller and contact members
Solution Approach 1:
The patent changes the physical parameters of the developing roller by controlling its electrostatic capacitance within a specific range (10-30 pF). This is achieved by adjusting the thickness and material properties of the elastic layer, which has a dielectric constant of 3-8. By optimizing these parameters, the roller maintains stable toner feeding while reducing distortion and stick slip effects during high-speed rotation.
Solution Approach 2:
The developing roller employs a composite structure consisting of a shaft core and an elastic layer with specific material properties. The elastic layer uses materials with controlled dielectric constants (3-8) and specific thickness ranges, creating a composite structure that balances mechanical stability for high-speed rotation with electrical properties that minimize distortion and stick slip between contact members.
2Object-generated harmful factors
If vibration and rotation unevenness are reduced to suppress stick slip, then banding is suppressed, but the complexity of driving members and gear improvements increases
Solution Approach 1:
The patent replaces mechanical solutions (gear improvements and vibration reduction mechanisms) with an electrical field-based approach. By controlling the electrostatic capacitance of the developing roller within 10-30 pF, the invention uses electrical field distribution to stabilize toner transfer and suppress banding, thereby avoiding the need for complex mechanical modifications to driving members and gears.
3Quantity of substance
If the nip width between the photoreceptor and developing roller changes due to distortion, then the amount of toner fed changes, but image quality deteriorates with banding
Solution Approach 1:
The patent establishes a feedback mechanism where the electrostatic capacitance of the developing roller (controlled at 10-30 pF) serves as a parameter that automatically regulates toner transfer. By maintaining the capacitance within this range, the system self-adjusts to compensate for nip width variations caused by distortion, ensuring consistent toner feeding amounts and preventing banding without requiring external control systems.
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 controlled electrostatic capacitance ensures smooth toner transfer and reduces banding in printed images, improving image quality and toner efficiency while maintaining low toner consumption.
Implementation Method 1
a reactive silicone oil, an isocyanate compound, and a diluting solvent capable of dissolving both the reactive silicone oil and the isocyanate compound are placed in a reaction vessel, allowed to react in the diluting solvent to perform a prepolymerization reaction while dissolution in the solvent is maintained
Implementation Method 2
The toner is charged by electrostatic friction at the developing roll and the toner regulating blade
Implementation Method 3
The toner is charged by electrostatic friction at the developing roll and the toner regulating blade, and transferred to an electrostatic latent image formed on the surface of the photoreceptor
Data Source
AI summary
A developing roller having a rubber elastomer layer on the outer periphery of a shaft core metal, having a coating layer formed from a binder (A) and silicone rubber particles (B) on the surface of the rubber elastomer, and having an electrostatic capacitance of 4 to 20 nF; wherein the binder (A) is formed from a diluting solvent solution of a terminal hydroxyl group-containing prepolymer (a) obtained by reaction of an isocyanate compound, an isocyanurate modified product thereof and a reactive silicone oil, and an isocyanate compound and/or an isocyanurate modified product thereof (b). This developing roller suppresses banding by suppressing electrostatic capacitance even if the nip width between the developing roll and the photoreceptor changes due to distortion of peripheral members in the development apparatus, and stick slip (vibration) of gears.