Electrophotographic photoreceptor, process cartridge, and image forming apparatus

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Solution Overview

Problem

Existing electrophotographic photoreceptors experience positive ghosting issues due to improper thickness and concentration ratios of the undercoat layer, leading to charge movement and potential fluctuations.

Innovation Solution

The photoreceptor is designed with a conductive substrate, an undercoat layer containing zinc oxide particles and a binder resin, a charge generation layer with titanium-containing organic pigment, and a charge transport layer, where the undercoat layer thickness is between 15.0 µm and 30.0 µm, and the Ti and Zn concentration ratios at the interface are optimized to 30-70% or 20-80% within ±500 nm, depending on the thickness range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the film thickness of the undercoat layer is less than 15.0 µm or more than 30.0 µm, then the manufacturing cost is reduced, but a positive ghost occurs due to charge movement and potential fluctuations

Engineering Contradiction:
Improvepositive ghost suppressionVSAvoidundercoat layer thickness
Core Design Contradiction:
Manufacturing precisionVSLength of moving object

Solution Approach 1:

The patent applies parameter changes by precisely controlling the film thickness of the undercoat layer within the range of 15.0 µm to 30.0 µm, and by optimizing the concentration ratios of Ti and Zn within specific ranges (30-70% or 20-80% depending on thickness). This quantitative parameter optimization resolves the contradiction by finding the optimal thickness range that suppresses positive ghost while avoiding excessive material use.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If the film thickness of the undercoat layer is 22.0 µm or more and 30.0 µm or less, then the positive ghost is suppressed, but the concentration ratios of Ti and Zn must be tightly controlled within 30-70%

Engineering Contradiction:
Improvepositive ghost suppressionVSAvoidconcentration ratio control
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent provides flexibility in concentration ratio control by offering two different parameter sets depending on the chosen thickness range. For thicker undercoat layers (22-30 µm), Ti and Zn concentrations should be 30-70%, while for thinner layers (15-22 µm), the range expands to 20-80%. This adaptive parameter strategy reduces manufacturing complexity compared to a single fixed concentration range.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If the film thickness of the undercoat layer is 15.0 µm or more and 22.0 µm or less, then the positive ghost is suppressed, but the concentration ratios of Ti and Zn must be controlled within 20-80%

Engineering Contradiction:
Improvepositive ghost suppressionVSAvoidconcentration ratio control
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent optimizes the concentration ratio parameters based on the selected thickness range. For the thinner undercoat layer range (15-22 µm), the patent specifies a broader concentration ratio range of 20-80% for both Ti and Zn, which provides manufacturing flexibility while still achieving positive ghost suppression through the synergistic effect of optimized thickness and composition.

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 suppresses positive ghosting by reducing energy gaps and inhibiting charge movement, maintaining consistent potential and improving image quality.

Implementation Method 1

an undercoat layer that is provided on the conductive substrate and contains zinc oxide particles and a binder resin; a charge generation layer that is provided on the undercoat layer and contains titanium-containing organic pigment and a binder resin

Methodology Applied
Scientific EffectPhotoconductivity: Photoconductivity

Data Source

PatentEP4657162A1Electrophotographic photoreceptor, process cartridge, and image forming apparatus
Publication Date: 2025.12.03 FUJIFILM BUSINESS INNOVATION CORP
  • EP4657162A1 patent drawingFigure 1~2
  • EP4657162A1 patent drawingFigure 3
  • EP4657162A1 patent drawing

AI summary

An electrophotographic photoreceptor includes a conductive substrate, an undercoat layer that is provided on the conductive substrate and contains zinc oxide particles and a binder resin, a charge generation layer that is provided on the undercoat layer and contains titanium-containing organic pigment and a binder resin, and a charge transport layer that is provided on the charge generation layer, in which a film thickness of the undercoat layer is 15.0 µm or more and 30.0 µm or less, in a case where the film thickness of the undercoat layer is 22.0 µm or more and 30.0 µm or less, each of a proportion of a Ti concentration and a proportion of a Zn concentration with respect to a total of the Ti concentration and the Zn concentration in a region within ±500 nm in a film thickness direction from an interface between the undercoat layer and the charge generation layer is 30% or more and 70% or less, and in a case where the film thickness of the undercoat layer is 15.0 µm or more and less than 22.0 µm, each of a proportion of a Ti concentration and a proportion of a Zn concentration with respect to a total of the Ti concentration and the Zn concentration in a region within ±500 nm in a film thickness direction from an interface between the undercoat layer and the charge generation layer is 20% or more and 80% or less.