Electrophotographic Photosensitive Member with Electron Transporting Layer

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Solution Overview

Problem

Electrophotographic photosensitive members suffer from positive ghosting and decreased charging capability due to retained charges in the electron transporting layer, which existing technologies fail to adequately address, especially with non-uniform electron mobility and insufficient reduction of ghosting phenomena.

Innovation Solution

A laminated electrophotographic photosensitive member is developed with a hole transporting layer, an electron transporting layer formed by polymerizing a composition containing an electron transporting substance, a thermoplastic resin, and a crosslinking agent, where the electron transporting substance has a polymerizable functional group content of 30-70% by mass, and specific thickness and potential decay conditions are met to optimize charge movement and retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If charge generating substances with higher sensitivity are used, then charge generation capability is improved, but charge retention in the photosensitive layer increases causing positive ghosting

Engineering Contradiction:

Improvecharge generation capabilityVSAvoidpositive ghosting

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

An electron transporting layer is introduced as an intermediary between the support and the charge generating layer. This layer mediates charge management by transporting electrons away from the charge generating layer, preventing charge retention and positive ghosting while allowing high-sensitivity charge generating substances to be used effectively.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The photosensitive member is segmented into distinct functional layers: a support, an electron transporting layer, and a charge generating layer. This segmentation allows each layer to perform its specific function optimally - the electron transporting layer handles electron transport to prevent ghosting, while the charge generating layer focuses on charge generation with high sensitivity materials.

Inventive Principle:

Principle #1Segmentation

2Object-generated harmful factors

If an electron transporting layer is added to suppress positive ghosting, then ghosting is reduced, but device complexity increases

Engineering Contradiction:

Improvepositive ghostingVSAvoidlayer structure complexity

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The electron transporting layer performs multiple functions simultaneously: it transports electrons to prevent charge retention and positive ghosting, while also serving as a structural component of the photosensitive member. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If the electron transporting layer has insufficient uniformity, then manufacturing is simplified, but charging capability decreases after repeated use

Engineering Contradiction:

Improvelayer uniformityVSAvoidcharging capability stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The electron mobility of the electron transporting layer is optimized to specific parameter ranges (10^-6 to 10^-8 cm²/Vs) to ensure sufficient electron transport capability. This parameter optimization maintains charging capability stability over repeated use while allowing for practical manufacturing tolerances in layer uniformity.

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 effectively suppresses positive ghosting and maintains charging capability over repeated use by ensuring sufficient electron mobility and retention in the electron transporting layer, improving image quality and device performance.

Implementation Method 1

an undercoating layer is made to be a layer (hereinafter, also referred to as an electron transporting layer) having an electron transporting capability

Methodology Applied

Scientific EffectElectron transport: Conduction (electrical)

Implementation Method 2

the electron transporting layer comprises a polymer obtained by polymerizing a composition comprising an electron transporting substance having a polymerizable functional group

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP2680076B1Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus

Publication Date: 2016.03.02 CANON KK

Figure 1~2
Figure 3A~3B
Figure 4A~4B

AI summary

An electrophotographic photosensitive member has a laminated body and a hole transporting layer formed on the laminated body, wherein the laminated body has a support, an electron transporting layer and a charge generating layer in this order, and satisfies the following expressions (2) and (4): Vl⁢2-Vl⁢1≤0.35 0.10≤Vd⁢2-Vl⁢3/Vd⁢2≤0.20