Electrophotographic Photoreceptor Light Shielding Undercoat

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Solution Overview

Problem

Electrophotographic photoreceptors suffer from optical fatigue when exposed to light, particularly at wavelengths around 450 nm, leading to reduced charge generation ability and image defects such as uneven image density.

Innovation Solution

The use of a charge transport layer with light transmittance of 30% or less and an undercoat layer with light transmittance of 20% or less, both with specific thickness ranges, is implemented to suppress exposure of the charge generation layer to light, thereby enhancing optical fatigue resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the charge generation layer is exposed to light (particularly at 450 nm), then charge generation function is activated, but optical fatigue occurs leading to reduced charge generation ability and image defects

Engineering Contradiction:

Improvecharge generation abilityVSAvoidoptical fatigue

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A light-shielding undercoat layer is introduced as an intermediary between the light source and the charge generation layer. This undercoat layer selectively blocks harmful blue light (450 nm) while allowing necessary exposure light to reach the charge generation layer, thereby preventing optical fatigue without compromising charge generation function

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The photoreceptor structure is segmented into functional layers: a light-shielding undercoat layer, a charge generation layer, and a charge transport layer. This segmentation allows each layer to perform its specific function - the undercoat layer blocks harmful light, while the charge generation layer remains accessible to necessary exposure light through controlled light transmission

Inventive Principle:

Principle #1Segmentation

2Reliability

If a light-shielding layer is added to protect the charge generation layer, then optical fatigue resistance is improved, but device complexity increases

Engineering Contradiction:

Improveoptical fatigue resistanceVSAvoidphotoreceptor structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The undercoat layer is designed to serve multiple functions simultaneously: it acts as a light-shielding layer to block harmful blue light, provides a mechanical base for the charge generation layer, and maintains electrical conductivity. This multi-functionality reduces the need for separate protective layers, thereby limiting the increase in device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If the undercoat layer and charge transport layer have high light transmittance, then charge generation efficiency is improved, but optical fatigue increases due to excessive light exposure

Engineering Contradiction:

Improvecharge generation efficiencyVSAvoidlight exposure to charge generation layer

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The light transmittance parameters of the undercoat layer and charge transport layer are precisely controlled and optimized. The undercoat layer is designed with specific optical properties to block harmful blue light while the charge transport layer has optimized transmittance to allow necessary exposure light, achieving a balance between charge generation efficiency and optical fatigue prevention

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

This configuration significantly reduces optical fatigue, resulting in improved image quality by minimizing image defects and maintaining high charge generation ability even with phthalocyanine-based charge generation layers.

Implementation Method 1

an undercoat layer that is provided on the conductive support and that has a thickness of from 15 μm to 40 μm and has light transmittance of 20% or less with respect to light having a wavelength of 450 nm

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS8956793B2Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Publication Date: 2015.02.17 FUJIFILM BUSINESS INNOVATION CORP

AI summary

An electrophotographic photoreceptor includes a conductive support, an undercoat layer that is provided on the conductive support and that has a thickness of from 15 μm to 40 μm and has light transmittance of 20% or less with respect to light having a wavelength of 450 nm when the thickness is at least 15 μm, a charge generation layer that is provided on the undercoat layer, and a charge transport layer that is provided on the charge generation layer and that has a thickness of from 15 μm to 40 μm and has light transmittance of 30% or less with respect to light having a wavelength of 450 nm when the thickness is at least 15 μm.