Developing Roller Non-Uniform Coating for Image Density

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Solution Overview

Problem

Existing developing devices in electrographic image forming apparatuses face issues with inconsistent toner image density and wear of the development roller's surface layer due to varying toner concentration and abrasive forces, leading to fluctuations in the gap between the development roller and the photosensitive drum, which affects image quality and longevity.

Innovation Solution

A developing device with a development roller having a cylindrical base and a surface layer formed through a dipping process, where the surface layer is thicker at the lower end during dipping, ensuring a consistent gap and reduced wear, and a magnetic roller with a developer limiting blade to maintain uniform developer thickness, along with a drive transmission section for rotational force, stabilizes the toner supply and image formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the development roller uses a uniform thickness surface layer, then the manufacturing process is simple, but the image density becomes inconsistent and the roller wears unevenly

Engineering Contradiction:

Improveimage density consistencyVSAvoidsurface layer formation process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The surface layer of the development roller is designed with non-uniform thickness, being thicker at the lower axial end and thinner at the upper axial end. This local variation in thickness compensates for the non-uniform abrasive forces and toner concentrations at different positions, ensuring consistent image density across the entire width of the developed image.

Inventive Principle:

Principle #3Local quality

2Duration of action of moving object

If the development roller surface layer is thinner, then the roller rotates faster with less inertia, but the surface layer wears out quickly reducing lifespan

Engineering Contradiction:

Improvedevelopment roller lifespanVSAvoidroller rotation speed

Core Design Contradiction:

Duration of action of moving objectVSSpeed

Solution Approach 1:

The surface layer thickness is varied axially along the roller, with the lower end having greater thickness to withstand higher abrasive forces and extend lifespan, while the upper end has smaller thickness to reduce rotational inertia and allow faster acceleration.

Inventive Principle:

Principle #3Local quality

3Speed

If the development roller surface layer is thicker, then the roller lifespan is extended, but the roller has higher inertia reducing rotation speed

Engineering Contradiction:

Improveroller rotation speedVSAvoiddevelopment roller lifespan

Core Design Contradiction:

SpeedVSDuration of action of moving object

Solution Approach 1:

The surface layer is designed with non-uniform thickness distribution, being thicker at the lower axial end where it is needed for durability against abrasive forces, and thinner at the upper axial end where reduced mass allows for faster rotation and lower inertia.

Inventive Principle:

Principle #3Local quality

4Duration of action of stationary object

If the surface layer thickness is non-uniform, then wear is reduced and lifespan is extended, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvedevelopment roller service lifeVSAvoidsurface layer formation

Core Design Contradiction:

Duration of action of stationary objectVSEase of manufacture

Solution Approach 1:

The non-uniform surface layer is formed during the manufacturing process by controlling the dipping speed and withdrawal speed of the base into the resin bath. This preliminary formation of the desired thickness profile during manufacturing simplifies subsequent usage, as the roller is already optimized for uniform wear resistance and performance without requiring additional post-processing steps.

Inventive Principle:

Principle #10Preliminary action

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

This configuration maintains stable image density and extends the lifespan of the development roller's surface layer, ensuring consistent image quality over a long period by minimizing wear and maintaining a strong developing electric field, even under high print coverage rates.

Implementation Method 1

The surface layer is formed through a dipping process of dipping the base into a dipping bath with the base directed axially vertically

Methodology Applied

Scientific EffectDeposition (physical): Deposition (physical)

Implementation Method 2

a magnetic roller with a developer limiting blade to maintain uniform developer thickness

Methodology Applied

Scientific EffectMagnetism: Magnetism

Data Source

PatentUS9298126B2Developing device and image forming apparatus including the same

Publication Date: 2016.03.29 KYOCERA DOCUMENT SOLUTIONS INC

AI summary

A developing device includes a housing, a development roller, and a roller gear. The roller gear is disposed at one axial end of the development roller and transmits a rotational drive force to the development roller. The development roller includes a sleeve and a coating layer. The coating layer is formed by dipping the sleeve in a dipping bath with the sleeve directed axially vertically. The development roller is mounted to the housing such that a lower axial end of the development roller at the time of the dipping is an opposite axial end to the one axial end at which the roller gear is disposed.