Developing Roller Grooves Enhance Toner Conveying Force

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Solution Overview

Problem

Existing developing rollers face a reduction in toner conveying force in high-temperature and high-humidity environments, leading to inadequate toner layer formation and image quality issues due to decreased electrical resistance in insulating regions, which affects the gradient power necessary for effective toner adsorption.

Innovation Solution

A developing roller with an electro-conductive layer featuring an electrical insulating first region and an electro-conductive second region, where the first region has grooves that enhance electric field concentration and gradient power through the edge effect, maintaining stable toner distribution and conveying force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the roller diameter is reduced for downsizing, then the device size is reduced, but the toner layer formation becomes insufficient and image uniformity deteriorates

Engineering Contradiction:
Improveroller volumeVSAvoidimage uniformity
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The developing roller surface is divided into distinct regions with different electrical properties: a dielectric region with high electric resistance for toner adsorption and an electroconductive region for charge dissipation. This local differentiation of electrical characteristics allows the roller to maintain effective toner conveying force even with reduced diameter, resolving the contradiction between downsizing and image uniformity.

Inventive Principle:
Principle #3Local quality

2Use of energy by moving object

If the toner layer amount is reduced for energy saving, then the energy consumption is reduced, but the image quality deteriorates

Engineering Contradiction:
Improveenergy consumptionVSAvoidimage quality
Core Design Contradiction:
Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The invention changes the electrical resistance parameter of the roller surface by creating regions with different conductivity characteristics. The dielectric region's high electric resistance enables strong toner adsorption through electrical attraction, allowing a thin toner layer to convey sufficient toner particles to the photoreceptor, thus maintaining image quality while reducing the overall toner layer amount and energy consumption.

Inventive Principle:
Principle #35Parameter changes

3Force

If the dielectric part has high electric resistance for toner adsorption, then the toner conveying force is improved, but the performance deteriorates in high-temperature and high-humidity environments

Engineering Contradiction:
Improvetoner conveying forceVSAvoidenvironmental stability
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The roller surface is segmented into multiple functional regions: dielectric regions for toner adsorption and electroconductive regions for charge management. The electroconductive regions act as charge dissipation paths that prevent excessive charge accumulation and maintain stable electrical characteristics in high-temperature and high-humidity environments, thereby improving reliability while preserving toner conveying force.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The electroconductive regions serve as intermediary elements between the dielectric regions and the roller core. They mediate the electrical charge distribution, providing stable reference potential and preventing environmental humidity from significantly affecting the dielectric regions' toner adsorption capability, thus maintaining consistent performance across varying environmental conditions.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 ensures a durable and stable toner coating on the developing roller, maintaining high image quality even in challenging environmental conditions by enhancing toner conveying force and reducing environmental variations.

Implementation Method 1

one or more grooves in the first region in the outer surface of the developing roller enhance electric field concentration and gradient power through the edge effect

Methodology Applied
Scientific EffectElectric field concentration: Electric Field

Implementation Method 2

allowing a charged dielectric part to electrically absorb the toner thereto

Methodology Applied
Scientific EffectElectrostatic adsorption: Electrostatic Induction

Implementation Method 3

an electro-conductive second region adjacent to the first region

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3627229B1Developing roller, electrophotographic process cartridge and electrophotographic image forming apparatus
Publication Date: 2022.10.12 CANON KK
  • EP3627229B1 patent drawingFigure 1
  • EP3627229B1 patent drawingFigure 2
  • EP3627229B1 patent drawingFigure 3

AI summary

To provide a developing roller having improved toner conveying force in a high-temperature and high-humidity environment. The developing roller has a substrate and an electro-conductive layer on the substrate. The outer surface of the developing roller has an electrical insulating first region and an electro-conductive second region adjacent to the first region and at the same time has at least one groove in the first region.