Charging Member Surface Layer for Abnormal Discharge Suppression

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Solution Overview

Problem

The increasing speed of electrophotographic image forming processes leads to a shortening of the charging time for photosensitive members, resulting in unstable and unreliable charging, particularly causing local and strong abnormal discharges under low temperature and low humidity conditions.

Innovation Solution

A charging member with a surface layer containing specific compounds such as polymetalloxanes or metal alkoxides, where the compounds coordinate with metal atoms to modify the energy levels of the surface layer, reducing the discharge start voltage and suppressing abnormal discharges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the process speed is increased to improve productivity, then the charging time is shortened, but the charging stability deteriorates causing abnormal discharge

Engineering Contradiction:
Improveprocess speedVSAvoidcharging stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the surface layer by incorporating specific metal compounds (ti, Zr, Hf, V, Nb, Ta, W, Al, Ga, In, or Ge compounds) in controlled amounts (0.1-10 mass%) to modify the discharge characteristics and prevent abnormal discharge at high speeds

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite surface layer structure combining the base conductive elastic layer with a surface layer containing metal compounds, forming a multi-layer composite material that maintains charging stability under high-speed operation conditions

Inventive Principle:
Principle #40Composite materials

2Reliability

If the contact nip is secured using a conductive elastic layer, then the charging function is improved, but low-molecular weight component bleeding occurs causing image defects

Engineering Contradiction:
Improvecharging functionVSAvoidimage defect
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies a thin surface layer (1-10 μm) over the conductive elastic layer, creating a flexible protective film that prevents low-molecular weight component bleeding while preserving the underlying elastic layer's charging functionality

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The surface layer acts as an intermediary barrier between the conductive elastic layer and the photosensitive member, preventing direct contact and thus preventing bleeding of low-molecular weight components while still allowing charge transfer

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If the charging time is shortened to match increased process speed, then the productivity is improved, but the discharge uniformity deteriorates causing uneven images

Engineering Contradiction:
Improvecharging speedVSAvoiddischarge uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent modifies the surface layer's chemical composition by adding specific metal compounds that alter the electrical and discharge characteristics, enabling uniform discharge even during brief high-speed charging cycles

Inventive Principle:
Principle #35Parameter changes

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 prevents local and strong abnormal discharges even under low temperature and low humidity conditions, ensuring stable charging and high-quality electrophotographic image formation.

Implementation Method 1

the compounds coordinate with metal atoms to modify the energy levels of the surface layer

Methodology Applied
Scientific EffectCoordination chemistry: Chemical Bonding

Implementation Method 2

reducing the discharge start voltage and suppressing abnormal discharges

Methodology Applied
Scientific EffectElectrostatic discharge: Electrostatic Discharge

Data Source

PatentEP3088961B1Charging member, process cartridge, and electrophotographic image formation device
Publication Date: 2021.03.10 CANON KK
  • EP3088961B1 patent drawingFigure 1~2
  • EP3088961B1 patent drawingFigure 3
  • EP3088961B1 patent drawingFigure 4

AI summary

Provided is a charging member which suppresses the occurrence of abnormal discharge at low temperatures and low humidity. A charging member having a support body and a surface layer on the support body, wherein the surface layer has a compound represented by formula (a) or (c), and a ligand thereof having a specific structure is coordinated to the metal atom of a polymetalloxane (the metal atom being one or more selected from a group consisting of Ti, Zr, Hf, V, Nb, Ta, W, Al, Ga, In and Ge), or to the metal atom of a metal alkoxide or metal hydroxide which have a metal atom.