Undercoat Layer Ghosting Reduction in Electrophotographic Photosensitive Members

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional electrophotographic photosensitive members using phthalocyanine or azo pigments suffer from ghosting issues, particularly in low temperature and low humidity environments, where existing solutions are insufficient in effectively reducing this phenomenon.

Innovation Solution

An electrophotographic photosensitive member is designed with an undercoat layer containing an amine compound represented by a specific formula, titanium oxide crystal particles with an average primary particle diameter of 3 nm to 15 nm, and an organic resin, which improves charge accumulation properties and reduces ghosting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an undercoat layer is disposed between support and photosensitive layer to improve adhesion and protect from electrical damage, then adhesion and protection are improved, but charges are easily accumulated therein causing ghosting

Engineering Contradiction:
Improveadhesion and protectionVSAvoidcharge accumulation and ghosting
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the undercoat layer by incorporating specific electron transporting substances (2,4,7-trinitro-9-fluorenone and/or 2,4,7-trinitro-9-phenyl-9H-fluorene) at controlled concentrations (0.01-10% by mass), which modifies the electrical properties to reduce charge accumulation while maintaining adhesion and protection functions

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The undercoat layer is designed as a composite material combining the electron transporting substances with binder resins (polyester, polyacrylate, or vinyl resin), creating a multi-component system that simultaneously achieves adhesion, protection, and reduced charge accumulation properties

Inventive Principle:
Principle #40Composite materials

2Measurement precision

If phthalocyanine pigment or azo pigment is used as charge generating substance to achieve high sensitivity, then sensitivity is improved, but electrons are easily accumulated causing ghosting

Engineering Contradiction:
ImprovesensitivityVSAvoidelectron accumulation and ghosting
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The electron transporting substances in the undercoat layer act as intermediary elements that capture and transport excess electrons generated by phthalocyanine or azo pigments, preventing their accumulation at the photosensitive layer-undercoat layer interface and thereby reducing ghosting while maintaining high sensitivity

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent substitutes the conventional approach of relying solely on the photosensitive layer composition to manage charge accumulation with a new mechanism using electron transporting substances in the undercoat layer to actively manage electron transport and prevent accumulation

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Object-generated harmful factors

If conventional arts are used to reduce ghosting, then ghosting is reduced in normal environments, but ghosting is insufficiently reduced under low temperature and low humidity environment

Engineering Contradiction:
Improveghosting in normal environmentVSAvoidghosting reduction in low temperature and low humidity environment
Core Design Contradiction:
Object-generated harmful factorsVSAdaptability or versatility

Solution Approach 1:

The patent optimizes the molecular structure parameters of the electron transporting substances by selecting specific compounds (2,4,7-trinitro-9-fluorenone and/or 2,4,7-trinitro-9-phenyl-9H-fluorene) with appropriate electron affinity and mobility characteristics, enabling effective ghosting reduction across varying environmental conditions including low temperature and low humidity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The undercoat layer composition is designed to perform multiple functions universally: maintaining adhesion, providing electrical protection, and reducing ghosting under diverse environmental conditions (normal, low temperature, low humidity), making the photosensitive member adaptable to various operating environments

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 proposed solution effectively reduces ghosting in both normal and low temperature and low humidity environments, maintaining electrification properties and improving the stability of the photosensitive member.

Implementation Method 1

the undercoat layer includes: an amine compound represented by the following formula (1); titanium oxide crystal particles having an average primary particle diameter of 3 nm or more and 15 nm or less; and an organic resin

Methodology Applied
Scientific EffectElectron trapping: Adsorption

Data Source

PatentEP2733539B1Electrophotographic photosensitive member, process cartridge and electrophotographic apparatus
Publication Date: 2016.02.03 CANON KK
  • EP2733539B1 patent drawingFigure 1~2
  • EP2733539B1 patent drawingFigure 3
  • EP2733539B1 patent drawing

AI summary

An electrophotographic photosensitive member includes a support, an undercoat layer formed on the support, and a photosensitive layer which is formed on the undercoat layer and contains a charge generating substance and a hole transporting substance. The undercoat layer contains a specific amine compound, titanium oxide crystal particles having an average primary particle diameter of 3 nm or more and 15 nm or less and an organic resin.