Monolayer Photoconductor Suppressing Exposure Memory
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Solution Overview
Problem
Existing electrophotographic photoconductors, particularly positive charged monolayer type photoconductors, suffer from exposure memory issues due to elongated electron transport distances and low charge transport efficiency, leading to inconsistent image density and poor image quality.
Innovation Solution
A monolayer type electrophotographic photoconductor is developed with a photoconductive layer containing oxo-titanyl phthalocyanine crystal, electron transfer agent with a reduction potential between -0.97 to -0.83 V, and a specific formula (A·C−1·d−1>1.75×10^4) that enhances dispersibility and charge transport, suppressing exposure memory and improving sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a positive charged monolayer type photoconductor is used, then the device structure is simple, but exposure memory occurs conspicuously due to elongated electron transport distance
Solution Approach 1:
The photoconductive layer is segmented into distinct functional regions: a charge generation layer containing oxo-titanyl phthalocyanine crystal for light-induced charge generation, and a charge transport layer containing electron transfer agent and hole transfer agent for charge transport. This segmentation allows optimization of each layer's function to reduce electron transport distance and suppress exposure memory while maintaining structural simplicity.
Solution Approach 2:
The invention optimizes parameters including the reduction potential of the electron transfer agent (set to -0.97 to -0.83 V), the concentration of oxo-titanyl phthalocyanine crystal (0.1 to 5 weight%), and the film thickness (5 to 50 μm) to achieve effective exposure memory suppression while maintaining simple monolayer structure.
2Productivity
If the electron transfer agent has high mobility comparable to hole transfer agent, then charge transport efficiency improves, but such material has not been developed yet
Solution Approach 1:
The invention specifies a particular reduction potential range for the electron transfer agent (-0.97 to -0.83 V) to achieve optimal charge transport efficiency. This parameter specification allows selection from available materials that meet the performance requirement without requiring entirely new material development.
3Productivity
If the photoconductor operates at high speed, then productivity improves, but exposure memory suppression becomes more difficult
Solution Approach 1:
The photoconductive layer is pre-designed with optimized parameters including the concentration of oxo-titanyl phthalocyanine crystal (0.1 to 5 weight%) and film thickness (5 to 50 μm) to ensure that exposure memory is suppressed from the outset during high-speed operation, eliminating the need for post-operation corrections.
4Measurement precision
If the photoconductive layer has high sensitivity to exposure, then image formation quality improves, but charge transport efficiency may be compromised
Solution Approach 1:
The photoconductive layer is divided into charge generation and charge transport functions within the same layer, allowing the oxo-titanyl phthalocyanine crystal to provide high sensitivity for exposure while the electron and hole transfer agents ensure efficient charge transport, achieving both high sensitivity and high productivity.
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 suppresses exposure memory and enhances sensitivity, allowing for high-quality image formation at high speeds without the need for an electricity neutralizing means, simplifying and miniaturizing the image forming apparatus.
Implementation Method 1
a monolayer type electrophotographic photoconductor is developed with a photoconductive layer containing oxo-titanyl phthalocyanine crystal
Implementation Method 2
the electron transfer agent has a reduction potential thereof set to a value which falls within a range from −0.97 to −0.83 V
Data Source
AI summary
The present invention provides a monolayer type electrophotographic photoconductor which can effectively suppress the generation of an exposure memory and exhibits high sensitivity and an image forming apparatus using the monolayer type electrophotographic photoconductor. In an electrophotographic photoconductor which has a monolayer type photoconductive layer including at least a charge generating agent, a hole transfer agent, an electron transfer agent and a binding resin on a substrate, the charge generating agent contains oxo-titanyl phthalocyanine crystal, the electron transfer agent has a reduction potential thereof set to a value which falls within a range from −0.97 to −0.83 V, and the reflection absorbance (A/−) of the photoconductive layer with respect to light having a wavelength of 700 nm, a film thickness (d/m) of the photoconductive layer, and the concentration (C/weight %) of the oxo-titanyl phthalocyanine crystal of the photoconductive layer (100 weight %) satisfy a following formula (1).A·C−1·d−1>1.75×104 (1)