Electrophotographic Photosensitive Member Copolymer Ghosting

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Solution Overview

Problem

Existing electrophotographic photosensitive members suffer from positive ghosting issues, where areas exposed to light appear as halftone images, leading to reduced image quality and increased image density, which current technologies have not adequately addressed.

Innovation Solution

Incorporating a specific copolymer with alternating electron transport and other structural units into the photosensitive layer, which contains carboxyl groups, to improve the arrangement and distribution of electron transport structures, thereby reducing positive ghosting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an intermediate layer is provided between the photosensitive layer and the support to prevent peeling and defects, then adhesion and defect prevention are improved, but electrophotographic performance deteriorates

Engineering Contradiction:

Improveadhesion and defect preventionVSAvoidelectrophotographic performance

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent removes the intermediate layer from the photosensitive member structure. By directly forming the photosensitive layer on the support surface, it eliminates the harmful intermediate layer that caused poor electrophotographic performance while maintaining adequate adhesion through proper surface treatment of the support.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of adding an intermediate layer to solve adhesion problems, the patent inverts the approach by removing any intermediate layer and directly forming the photosensitive layer on the support. This inversion resolves the contradiction by showing that the intermediate layer itself is the problem, not the solution.

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of manufacture

If conventional photosensitive layer structures are used, then manufacturing simplicity is maintained, but positive ghosting occurs and image quality deteriorates

Engineering Contradiction:

Improvestructure simplicityVSAvoidimage quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters of the photosensitive layer by incorporating a specific copolymer with electron transport units and other units in a controlled ratio (0.1-10 mol%). This parameter change eliminates positive ghosting while maintaining a simple two-layer structure, thus resolving the contradiction between manufacturing simplicity and image quality.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite polymer material consisting of electron transport units and other units copolymerized together. This composite structure provides both the simplicity of a single-layer formulation and the advanced functionality needed to eliminate positive ghosting, achieving high image quality without complex multi-layer structures.

Inventive Principle:

Principle #40Composite materials

3Manufacturing precision

If electron transport materials are incorporated to reduce positive ghosting, then image quality improves, but the complexity of material composition increases

Engineering Contradiction:

Improvepositive ghosting reductionVSAvoidmaterial composition complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges the electron transport function with the binder resin by copolymerizing electron transport units directly into the polymer chain. This combination eliminates the need for separate electron transport material additions, reducing compositional complexity while maintaining the ghosting reduction benefit.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The copolymer serves multiple functions simultaneously: it acts as the binder resin, provides electron transport capability, and controls the arrangement of electron transport structures. This multi-functionality reduces the need for additional materials and simplifies the overall composition while achieving ghosting reduction.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 copolymer effectively minimizes positive ghosting, enhancing the quality of electrophotographic images by ensuring proper arrangement of electron transport structures and improving the overall performance of the electrophotographic photosensitive member.

Implementation Method 1

Methodology Applied

Scientific EffectElectron transport: Conduction (electrical)

Data Source

PatentEP2391925B1Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus

Publication Date: 2018.09.19 CANON KK

AI summary

To provide an electrophotographic photosensitive member that can reproduce good images with less positive ghost and also has a good photosensitivity, the electrophotographic photosensitive member is incorporated in its photosensitive layer with a copolymer having a repeating structural unit represented by the formula (1) and a repeating structural unit represented by the formula (2), or a copolymer having a repeating structural unit represented by the formula (1) and a repeating structural unit represented by the formula (3).