Electrophotographic Photoreceptor Transfer Memory Control

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Solution Overview

Problem

In electrophotographic photoreceptors, particularly in direct transfer systems, transfer memory defects such as band-like white voids occur due to uneven transfer voltage application, leading to persistent image defects that are difficult to resolve, especially when printing on varying paper sizes, causing density differences and image instability.

Innovation Solution

The use of a charge transport layer with a specific polyester resin and a non-halogen solvent, combined with a charge generation layer containing hydroxygallium phthalocyanine synthesized using a halogen solvent, helps prevent transfer memory by stabilizing the photoreceptor potential and enhancing abrasion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a direct transfer system is used for high-speed printing, then productivity is improved, but transfer memory defects occur due to uneven transfer voltage application

Engineering Contradiction:

Improveprinting speedVSAvoidimage quality stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent modifies the electrical parameters of the photoreceptor by controlling the potential distribution in the photosensitive layer. Specifically, it adjusts the potential at different positions (Vx at position x, Vy at position y) to compensate for the uneven transfer voltage, ensuring uniform charge distribution and preventing transfer memory defects while maintaining high-speed direct transfer printing

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback mechanism where the potential distribution in the photosensitive layer is continuously adjusted based on the transfer voltage application. The system monitors the charge distribution and modifies the electrical parameters to maintain uniformity, thereby preventing the accumulation of transfer memory effects during high-speed printing

Inventive Principle:

Principle #23Feedback

2Productivity

If transfer voltage is continuously applied to uninvolved photoreceptor portions during small-size paper printing, then productivity is maintained, but harmful electrical effects accumulate causing band-like white voids

Engineering Contradiction:

Improvecontinuous printing capabilityVSAvoidtransfer memory defects

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality control by differentiating the potential management between printed and unprinted portions of the photoreceptor. It specifically addresses the uninvolved portions (where no paper is printed) by applying different potential control strategies (Vy at position y) to prevent charge accumulation, while maintaining the necessary transfer voltage application during continuous printing operations

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements preliminary anti-action by preemptively controlling the potential distribution in the photosensitive layer before transfer memory defects can develop. It applies counteracting electrical fields to the uninvolved photoreceptor portions to prevent charge accumulation, thereby preventing band-like white voids before they occur during continuous small-size paper printing

Inventive Principle:

Principle #9Preliminary anti-action

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 ensures excellent image stability and reduced occurrence of transfer memory defects, maintaining image quality and density uniformity even with varying paper sizes, and prevents persistent image defects like band-like white voids.

Implementation Method 1

a charge generation layer and a charge transport layer on the conductive support

Methodology Applied

Scientific EffectPhotoconductivity: Photoconductivity

Implementation Method 2

the charge transport layer contains a polyester resin having a structural unit represented by the following formula (6)

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS9880477B2Electrophotographic photoreceptor and image forming apparatus

Publication Date: 2018.01.30 MITSUBISHI CHEM CORP

AI summary

The invention provides an image forming apparatus and an electrophotographic photoreceptor, comprising: a conductive support; and at least a charge generation layer and a charge transport layer on the conductive support, wherein said charge generation layer contains a hydroxygallium phthalocyanine synthesized using a halogen solvent, said charge transport layer contains a polyester resin having a specific structural unit, and said charge transport layer is formed using a non-halogen solvent.