Developing Roller Insulating Domains for Toner Charge Uniformity

Solution Overview

Problem

Existing electrophotographic developing apparatuses face challenges in achieving sufficient toner-conveying force and uniform triboelectric charge under high-temperature and high-humidity environments, leading to issues like 'forging' and 'fogging' during high-density image printing.

Innovation Solution

A developing apparatus with a developing roller featuring an electro-conductive elastic layer and insulating domains, along with a developer regulating member having a projection portion, is designed to enhance toner conveyance and triboelectric charging, ensuring stable image quality across various environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the diameter of the developing roller and developer-supplying roller is reduced to decrease apparatus size and energy consumption, then the apparatus size and energy use are reduced, but the charge amount of the toner layer becomes insufficient and uniform image formation becomes difficult

Engineering Contradiction:

Improveenergy consumptionVSAvoiduniformity of toner layer charge amount

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The developing roller surface is segmented into insulating domains (high electric resistance) and conductive portions. The insulating domains are arranged in a specific pattern to create localized charge accumulation zones that enhance toner conveying force without requiring increased roller diameter or torque, thereby maintaining uniform charge distribution even in reduced-size apparatuses.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the developing roller surface are given different electrical properties - insulating domains with high electric resistance for toner adsorption and conductive portions for charge dissipation. This local differentiation allows the roller to simultaneously provide sufficient charge amount and uniform charge distribution without increasing overall size or energy consumption.

Inventive Principle:

Principle #3Local quality

2Volume of moving object

If the diameter of the developing roller and developer-supplying roller is reduced to decrease apparatus size and energy consumption, then the apparatus size and energy use are reduced, but the charge amount of the toner layer becomes insufficient during high-density printing

Engineering Contradiction:

Improveapparatus sizeVSAvoidcharge amount of toner layer

Core Design Contradiction:

Volume of moving objectVSQuantity of substance

Solution Approach 1:

The developing roller surface is segmented into insulating domains (high electric resistance) and conductive portions. The insulating domains are arranged in a specific pattern to create localized charge accumulation zones that enhance toner conveying force without requiring increased roller diameter or torque, thereby maintaining uniform charge distribution even in reduced-size apparatuses.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The electrical resistance parameter of the developing roller surface is changed by creating insulating domains with high electric resistance. This parameter change allows the roller to generate sufficient triboelectric charge in a compact size, as the insulating domains concentrate and maintain higher charge densities during high-density printing operations.

Inventive Principle:

Principle #35Parameter changes

3Force

If a dielectric portion with high electric resistance is arranged on the developing roller surface to improve toner-conveying force, then toner conveying force is enhanced, but triboelectric charge imparting ability is degraded and forging occurs in the image

Engineering Contradiction:

Improvetoner-conveying forceVSAvoidimage quality (forging prevention)

Core Design Contradiction:

ForceVSManufacturing precision

Solution Approach 1:

The developing roller surface is segmented into insulating domains (high electric resistance) and conductive portions. The insulating domains are arranged in a specific pattern to create localized charge accumulation zones that enhance toner conveying force without requiring increased roller diameter or torque, thereby maintaining uniform charge distribution even in reduced-size apparatuses.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the developing roller surface are given different electrical properties - insulating domains with high electric resistance for toner adsorption and conductive portions for charge dissipation. This local differentiation allows the roller to simultaneously provide sufficient charge amount and uniform charge distribution without increasing overall size or energy consumption.

Inventive Principle:

Principle #3Local quality

4Manufacturing precision

If the developer regulating member is designed to circulate toner through a toner reservoir to achieve uniform charge amount, then charge uniformity is improved, but the charge amount remains insufficient during high-density printing

Engineering Contradiction:

Improveuniformity of charge amountVSAvoidcharge amount during high-density printing

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

Different regions of the developing roller surface are given different electrical properties - insulating domains with high electric resistance for toner adsorption and conductive portions for charge dissipation. This local differentiation allows the roller to simultaneously provide sufficient charge amount and uniform charge distribution without increasing overall size or energy consumption.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The electrical resistance parameter of the developing roller surface is changed by creating insulating domains with high electric resistance. This parameter change allows the roller to generate sufficient triboelectric charge in a compact size, as the insulating domains concentrate and maintain higher charge densities during high-density printing operations.

Inventive Principle:

Principle #35Parameter changes

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 improves toner-conveying force and triboelectric charge imparting ability, reducing 'fogging' and maintaining high-quality image density, especially during high-density printing under challenging environmental conditions.

Implementation Method 1

the charged dielectric portion is caused to electrically adsorb a toner, thereby enabling the conveyance of the toner

Methodology Applied

Scientific EffectTriboelectric effect: Triboelectric Effect

Implementation Method 2

the charged dielectric portion is caused to electrically adsorb a toner, thereby enabling the conveyance of the toner

Methodology Applied

Scientific EffectElectrical adsorption: Electrostatics

Data Source

PatentUS9952532B2Developing apparatus, electrophotographic process cartridge, and electrophotographic image forming apparatus

Publication Date: 2018.04.24 CANON KK

AI summary

The developing apparatus includes: a developing roller rotatable in a first rotation direction; and a developer regulating member, wherein the developing roller includes: a substrate; an electro-conductive elastic layer on the substrate; and insulating domains on the electro-conductive elastic layer, wherein the electro-conductive elastic layer has a certain Martens hardness, the developing roller has a surface including surfaces of the insulating domains and a surface of the electro-conductive elastic layer, which is uncovered with the insulating domains at a certain area ratio, wherein the developer regulating member comprises: an abutting portion which is in contact with the surface of the developing roller, and a certain projection portion extending to an upstream side from the abutting portion in the first rotation direction, the developing apparatus has a certain gap between a side of the projection portion facing to the developing roller, and the surface of the developing roller.