Developing Member Surface Layer for Toner Charge Leakage

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Solution Overview

Problem

Electrophotographic developing members experience toner charge leakage under high temperature and high humidity environments, leading to reduced toner charging efficiency.

Innovation Solution

A developing member with an electro-conductive substrate and a surface layer containing a binder resin, alumina particles, and a polyester phosphate compound, which traps and recirculates toner charges to enhance toner charging properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional developing member is used, then the device structure remains simple, but toner charge leakage occurs under high temperature and high humidity environments

Engineering Contradiction:
Improvetoner charging efficiencyVSAvoidsurface layer composition
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The developing member surface layer is constructed as a composite material containing polyester phosphate compound, alumina particles, and binder resin. This composite structure prevents toner charge leakage while maintaining appropriate surface properties for effective toner charging, resolving the contradiction between reliability and structural simplicity.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention modifies the chemical composition parameters of the surface layer by incorporating polyester phosphate compound with specific molecular structure (Formula 1) and controlling the content of alumina particles and binder resin. These parameter changes enable the surface to resist charge leakage under high temperature and humidity while maintaining charging efficiency.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the developing member surface is made more electro-conductive to improve charging, then charging efficiency increases, but charge leakage to the developing member increases

Engineering Contradiction:
Improvetoner charging efficiencyVSAvoidcharge leakage
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The surface layer is designed with local quality differentiation through the composite structure: alumina particles provide localized charge generation sites, polyester phosphate compound provides charge trapping sites to prevent leakage, and binder resin provides structural continuity. This local quality distribution enables simultaneous achievement of high charging efficiency and low charge leakage.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The polyester phosphate compound acts as an intermediary between the electro-conductive substrate and the toner particles. It traps charges that would otherwise leak to the substrate while still allowing sufficient charge transfer to the toner, thus mediating between the conflicting requirements of charging efficiency and charge retention.

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 effectively maintains high toner charging efficiency and durability even under challenging environmental conditions, ensuring high-quality electrophotographic image formation.

Implementation Method 1

the surface layer containing a binder resin, alumina particles and a polyester phosphate compound... which traps and recirculates toner charges to enhance toner charging properties

Methodology Applied
Scientific EffectElectrostatic interaction: Electrostatics

Data Source

PatentEP3173871B1Developing member, process cartridge and electrophotographic image forming apparatus
Publication Date: 2019.06.12 CANON KK
  • EP3173871B1 patent drawingFigure 1~2
  • EP3173871B1 patent drawingFigure 3~4
  • EP3173871B1 patent drawing

AI summary

A high-quality developing member having compatibility between high toner charging properties and high durability under high temperature and high humidity environments is provided. The developing member includes an electro-conductive substrate and an electro-conductive surface layer in this order. The surface layer includes a binder resin, an alumina particle and a polyester phosphate compound.