Photoreceptor Layer Composition for Positive Ghost Suppression

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Solution Overview

Problem

Existing electrophotographic photoreceptors experience positive ghosting due to charge movement and injection issues at the interface between the undercoat and charge generation layers, particularly when the undercoat layer thickness is outside the optimal range or when the concentrations of Ti and Zn are not uniformly distributed.

Innovation Solution

The photoreceptor is designed with an undercoat layer thickness of 15.0 μm to 30.0 μm, and a specific concentration ratio of Ti and Zn within ±500 nm from the interface between the undercoat and charge generation layers, ensuring uniform dispersibility and reducing the energy gap, thereby inhibiting charge movement and injection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the film thickness of the undercoat layer is less than 15.0 μm or more than 30.0 μm, then the manufacturing process is simpler, but positive ghosting occurs due to charge movement and injection issues at the interface

Engineering Contradiction:

Improveundercoat layer thickness controlVSAvoidimage quality (positive ghost suppression)

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent specifies a precise film thickness range of 15.0 μm to 30.0 μm for the undercoat layer, along with controlled Ti and Zn concentration ratios (30-70% Ti and 70-30% Zn when thickness is 22.0-30.0 μm, or 20-80% Ti and 80-20% Zn when thickness is 15.0-22.0 μm). These parameter specifications resolve the contradiction by defining optimal manufacturing parameters that simultaneously ensure ease of production and suppress positive ghosting.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If the proportion of Ti concentration or Zn concentration is outside the specified range, then the material composition is easier to prepare, but charge stability deteriorates leading to positive ghosting

Engineering Contradiction:

Improvematerial composition controlVSAvoidcharge stability at interface

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent defines specific concentration ratio ranges for Ti and Zn at the interface region (within +500 nm from the interface). When undercoat thickness is 22.0-30.0 μm, Ti concentration should be 30-70% and Zn concentration 70-30%. When thickness is 15.0-22.0 μm, Ti concentration should be 20-80% and Zn concentration 80-20%. These parameter specifications ensure charge stability while maintaining manufacturing feasibility.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If the undercoat layer thickness is not optimized, then the device structure is simpler, but energy gap increases allowing charge movement and injection

Engineering Contradiction:

Improvelayer structure complexityVSAvoidcharge stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent optimizes the undercoat layer thickness to 15.0-30.0 μm and controls the Ti/Zn concentration ratios at the interface. This optimization reduces the energy gap at the interface between the undercoat and charge generation layers, preventing charge movement and injection. The solution maintains relatively simple layer structure while achieving reliable charge stability through precise parameter control.

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 effectively suppresses positive ghosting by maintaining charge stability and reducing potential fluctuations, even in image forming apparatuses without static current charging devices.

Implementation Method 1

ensuring uniform dispersibility and reducing the energy gap, thereby inhibiting charge movement and injection

Methodology Applied

Scientific EffectEnergy gap reduction:

Implementation Method 2

maintaining charge stability and reducing potential fluctuations

Methodology Applied

Scientific EffectCharge stability:

Data Source

PatentUS20250362625A1Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Publication Date: 2025.11.27 FUJIFILM BUSINESS INNOVATION CORP

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.