Charge Transporting Layer Gradient for Photosensitive Member Potential Stability
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Solution Overview
Problem
Electrophotographic photosensitive members used in high-speed printing processes fail to sufficiently suppress potential fluctuations due to charge trapping at the interface between the charge transporting layer and the charge generating layer, leading to image instability.
Innovation Solution
Incorporating a charge transporting layer with a compound represented by formula (C-1) and at least one of the compounds represented by formulas (C-2) or (C-3), with a specific mass ppm ratio of 250 to 610, to enhance hole pull-out and transport efficiency, thereby reducing charge accumulation and potential fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional charge transporting layers are used in high-speed printing processes, then printing speed is improved, but potential fluctuation increases due to charge trapping at the interface
Solution Approach 1:
The patent applies local quality by creating a charge transporting layer with non-uniform composition - specifically, a gradient structure where the ratio of charge transporting substance to binder resin varies with depth. The interface region between the charge transporting layer and charge generating layer has a higher concentration of charge transporting substance, which locally enhances charge extraction capability precisely where charge trapping occurs during high-speed printing operations.
Solution Approach 2:
The patent changes the compositional parameters of the charge transporting layer by controlling the depth-dependent ratio of charge transporting substance to binder resin. This parameter gradient allows the layer to maintain different functional characteristics at different depths - higher charge transport capability at the interface to prevent trapping, and appropriate bulk properties for overall charge transport during high-speed operation.
2Reliability
If the ratio of charge transporting substance to binder resin is increased at the interface, then charge trapping is suppressed, but manufacturing complexity increases
Solution Approach 1:
The patent implements parameter changes by establishing a depth-dependent compositional gradient in the charge transporting layer. The ratio of charge transporting substance to binder resin is controlled to increase toward the interface region, creating a continuous or stepped gradient structure that suppresses charge trapping while maintaining manufacturability through controlled coating processes.
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 proposed configuration effectively suppresses potential fluctuations during repeated use in high-speed printing processes, ensuring improved image stability and sensitivity.
Implementation Method 1
a charge transporting layer containing a charge transporting substance... to enhance hole pull-out and transport efficiency
Implementation Method 2
a charge generating layer containing a charge generating substance... and a charge transporting layer containing a charge transporting substance
Data Source
AI summary
An object of the present disclosure is to provide an electrophotographic photosensitive member which can suppress the potential fluctuation due to repeated use even with the electrophotographic apparatus of high printing process speed. The present disclosure provides an electrophotographic photosensitive member comprising: a support, a charge generating layer, and a charge transporting layer in this order, wherein the charge transporting layer comprises: (α) a compound represented by the formula (C-1), and (β) at least one selected from the group consisting of a compound represented by the following formula (C-2) and a compound represented by the formula (C-3), wherein a content of the (β) in the charge transporting layer with respect to a total mass of the charge transporting layer is 250 to 610 mass ppm.