Single-Layer Photosensitive Member with Graded Material Distribution

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Solution Overview

Problem

Existing electrophotographic photosensitive members with single-layer-type photosensitive layers face challenges in achieving high chargeability and light sensitivity while maintaining low residual potential, as the distribution of charge generation and electron transport materials affects their electrical properties and sensitivity.

Innovation Solution

The electrophotographic photosensitive member incorporates a single-layer-type photosensitive layer with a controlled distribution of charge generation material and fluorine-atom-containing electron transport material, where the charge generation material is localized in the surface-side region and the electron transport material is concentrated in the surface-side region to enhance chargeability and sensitivity, and fluorine-containing resin particles are used to maintain low residual potential.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the amount of charge generation material is increased to improve chargeability and light sensitivity, then chargeability and sensitivity are improved, but residual potential increases

Engineering Contradiction:

ImprovechargeabilityVSAvoidresidual potential

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by creating a non-uniform distribution of charge generation material and fluorine-atom-containing electron transport material within the photosensitive layer. The charge generation material is concentrated in the surface-side region (0-10 μm from surface) while the fluorine-atom-containing electron transport material is concentrated in the deeper region (10-20 μm from surface). This spatial differentiation allows high chargeability and sensitivity at the surface while maintaining low residual potential through proper electron transport in the underlying region.

Inventive Principle:

Principle #3Local quality

2Device complexity

If a single-layer-type photosensitive layer is used to simplify structure, then device complexity is reduced, but achieving high chargeability and low residual potential simultaneously becomes difficult

Engineering Contradiction:

Improvephotosensitive layer structureVSAvoidelectrical properties

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent uses local quality to differentiate functional regions within a single-layer structure. By controlling the concentration gradients of charge generation material and fluorine-atom-containing electron transport material at different depths, the single layer performs multiple functions: surface region provides high chargeability and sensitivity, while deeper regions provide electron transport and low residual potential. This eliminates the need for separate multi-layer structures.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies parameter changes by precisely controlling the concentration ratios of different materials at different positions within the layer. The charge generation material concentration is optimized to 0.5-2.0% by weight overall, with higher concentration at the surface. The fluorine-atom-containing electron transport material concentration is controlled to achieve c/d≥30, where c is concentration in surface-side region and d is concentration in base-side region. These parameter optimizations enable the single layer to achieve electrical properties comparable to or better than multi-layer structures.

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 results in a photosensitive member with high chargeability, high sensitivity, and low residual potential, improving the electrical properties and extending the longevity of the photosensitive member by suppressing changes in electrical properties during long-term use.

Implementation Method 1

a toner image that has been formed on a surface of an electrophotographic photosensitive member through a process that includes charging, electrostatic latent image forming, and developing

Methodology Applied

Scientific EffectPhotoexcitation: Photoelectric Effect

Implementation Method 2

a fluorine-atom-containing electron transport material, and fluorine-atom-containing resin particles

Methodology Applied

Scientific EffectElectron transport: Conduction (electrical)

Data Source

PatentUS9811010B2Electrophotographic photosensitive member, process cartridge, and image forming apparatus

Publication Date: 2017.11.07 FUJIFILM BUSINESS INNOVATION CORP

AI summary

An electrophotographic photosensitive member includes a conductive base and a single-layer-type photosensitive layer on the conductive base. The photosensitive layer contains a binder resin, a charge generation material, a hole transport material, a fluorine-atom-containing electron transport material, and fluorine-atom-containing resin particles. An amount of the charge generation material in the photosensitive layer is 0.5% by weight or more and less than 2.0% by weight. The charge generation material has a distribution that satisfies Formula (1): 30≦a/b in a thickness direction of the photosensitive layer where a and b are as defined in the specification, and b may be 0. The fluorine-atom-containing electron transport material has a distribution that satisfies Formula (2): 30≦c/d in the thickness direction of the photosensitive layer where c and d are as defined in the specification, and d may be 0.