Positively Chargeable Photosensitive Layer for Electrophotography
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Solution Overview
Problem
Existing electrophotographic photosensitive members face issues with exposure memory, leading to image defects due to residual charges and reduced charge ability in the photosensitive layer, which affects the quality of images formed.
Innovation Solution
A positively chargeable single-layer electrophotographic photosensitive member is developed, comprising a conductive substrate and a photosensitive layer containing a charge generating material, a hole transport material, an electron transport material, and an electron accepting compound, specifically using benzidine derivatives and compounds represented by general formulae (1) to (6), which enhances electron transport and reduces residual charges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional photosensitive layer is used, then the structure is simple, but exposure memory occurs leading to image defects
Solution Approach 1:
The photosensitive layer is constructed as a composite material system containing four key components: charge generating material (phthalocyanine derivative), hole transport material (benzidine derivative), electron transport material (compounds of formulae 1-4), and electron accepting compound (compounds of formulae 5-6). This composite structure enables simultaneous achievement of excellent charge generation, transport, and stabilization functions, eliminating exposure memory effects while maintaining structural integrity.
Solution Approach 2:
Different regions of the photosensitive layer are optimized for specific functions through spatial distribution of materials. The charge generating material is positioned to maximize light absorption and electron generation, while hole and electron transport materials are arranged to facilitate directional charge movement. This local optimization ensures efficient charge separation and transport, preventing residual charge accumulation that causes exposure memory.
2Reliability
If electron transport is enhanced, then residual charges are reduced, but the photosensitive layer composition becomes more complex
Solution Approach 1:
The patent optimizes specific parameters of the electron transport material molecules (formulae 1-4) and electron accepting compounds (formulae 5-6), including substituent groups (R1-R23), to enhance electron mobility and affinity. By carefully selecting and adjusting these molecular parameters, the system achieves superior electron transport efficiency and reduced residual charges while maintaining a manageable material composition through the use of well-defined chemical structures.
3Measurement precision
If sensitivity is improved, then image quality increases, but exposure memory effects worsen
Solution Approach 1:
The electron accepting compound (formulae 5-6) acts as an intermediary substance that mediates between the generated electrons and the electron transport material. This intermediary facilitates efficient electron transfer, enhances sensitivity by improving charge collection efficiency, while simultaneously preventing electron accumulation that would otherwise cause exposure memory effects. The benzidine derivative hole transport material also serves as a mediator in hole transport, balancing the charge distribution.
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 solution effectively restricts the occurrence of image defects from exposure memory and improves sensitivity by ensuring efficient electron transport and charge distribution, resulting in higher image quality and reduced ghosting in the images formed.
Implementation Method 1
a charge generating material, a hole transport material, an electron transport material, and an electron accepting compound
Implementation Method 2
The electron transport material includes at least one compound selected from the group consisting of compounds represented by general formulae (1), (2), (3), and (4)
Implementation Method 3
The hole transport material includes a benzidine derivative
Implementation Method 4
The electron accepting compound includes at least one compound selected from the group consisting of compounds represented by general formulae (5) and (6)
Data Source
AI summary
A positively chargeable single-layer electrophotographic photosensitive member includes a conductive substrate and a photosensitive layer. The photosensitive layer contains at least a charge generating material, a hole transport material, an electron transport material, and an electron accepting compound. The hole transport material includes a benzidine derivative. The electron transport material includes at least one compound selected from the group consisting of compounds represented by general formulae (1), (2), (3), and (4) shown below. The electron accepting compound includes at least one compound selected from the group consisting of compounds represented by general formulae (5) and (6) shown below.