Electrophotographic Photosensitive Member Surface Layer Image Flow

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Solution Overview

Problem

Electrophotographic photosensitive members face challenges in maintaining mechanical durability and electrical stability, leading to image blurring due to increased polar groups and ozone generation during the charging process, especially in high-temperature and high-humidity environments.

Innovation Solution

The development of an electrophotographic photosensitive member with a surface layer containing a copolymerized product of a hole transporting compound and a compound with a cyclic structure, which enhances film density and reduces water permeation, thereby suppressing image flow and maintaining adequate electrical characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the abrasion resistance of the electrophotographic photosensitive member is increased, then mechanical durability is improved, but the surface cannot be refreshed and material deteriorates by discharge, leading to increased polar groups and image flow

Engineering Contradiction:

Improvemechanical durabilityVSAvoidelectrical stability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent modifies the chemical composition parameters of the surface layer by incorporating specific compounds (formulae 1-4) with controlled polar group content. This changes the surface properties to reduce water solubility and prevent polar group accumulation, thereby maintaining electrical stability while preserving mechanical durability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The surface layer is formulated as a composite material containing multiple components: hole transporting compounds, compounds with formulae 1-4, and resins. This composite structure combines the benefits of high abrasion resistance with controlled electrical properties, preventing image flow while maintaining mechanical strength.

Inventive Principle:

Principle #40Composite materials

2Reliability

If polar groups increase due to molecular chain cleavage or oxidation, then surface resistance decreases, but electric charges move easily on the surface causing image blur

Engineering Contradiction:

Improveelectrical characteristicsVSAvoidimage quality

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent converts the harmful effect of polar group formation into a beneficial outcome by selecting compounds with formulae 1-4 that contain polar groups but have controlled water solubility. These compounds accept polar groups from molecular chain cleavage without dissolving in water, thereby maintaining surface resistance and preventing charge migration that causes image blur.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Power

If nitrogen oxides and ozone are generated by charging process, then charging efficiency is improved, but they dissolve in water content and decrease surface resistance

Engineering Contradiction:

Improvecharging efficiencyVSAvoidsurface resistance

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The compounds with formulae 1-4 create a chemically inert surface environment that resists reaction with nitrogen oxides and ozone generated during charging. The controlled polar groups and low water solubility prevent these charging byproducts from dissolving in the surface layer, thereby maintaining surface resistance despite continuous charging operations.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

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 suppresses image flow while maintaining mechanical durability and electrical stability, even in harsh environments, by improving film density and reducing water content on the surface layer.

Implementation Method 1

reduces water permeation, thereby suppressing image flow

Methodology Applied

Scientific EffectPermeation: Permeation

Implementation Method 2

a charging process involving the discharge

Methodology Applied

Scientific EffectDischarge: Electrostatic Discharge

Implementation Method 3

nitrogen oxides and ozone are generated by the charging process involving the discharge

Methodology Applied

Scientific EffectOzone generation: Ozone

Implementation Method 4

it becomes easy for polar groups to increase because of the cleavage or oxidation of molecular chains on the surface

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS10976677B2Electrophotographic photosensitive member, process cartridge and electrophotographic apparatus

Publication Date: 2021.04.13 CANON KK

AI summary

The present disclosure provides an electrophotographic photosensitive member that has mechanical durability, and can achieve both of suppression of an image flow and adequate electrical characteristics. In the electrophotographic photosensitive member having a support and a photosensitive layer provided on the support, a surface layer of the electrophotographic photosensitive member contains a copolymerized product of a composition containing a hole transporting compound represented by the following formula (1) and a compound represented by the following formula (3):