Developing Roller Moving Member for Toner Sticking

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Solution Overview

Problem

In electrophotographic image forming apparatuses, high-charge toner tends to stick to the developing roller surface due to increased electrostatic attachment force, making it difficult to restrict with the developing blade, leading to issues like fogging and density decrease, especially when using mono-component magnetic toner.

Innovation Solution

A developing apparatus with a moving member, such as a brush, is positioned at a magnetic pole position on the magnet roller to gently move the toner layer, reducing sticking and maintaining charge uniformity without mechanical rubbing, which helps in preventing toner degradation and ensuring consistent image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the charge amount of toner is increased to improve development responsiveness, then development responsiveness is improved, but toner easily sticks to the developing roller surface and becomes difficult to restrict by the developing blade

Engineering Contradiction:

Improvedevelopment responsivenessVSAvoidtoner restriction by developing blade

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The moving member (brush roller) performs preliminary action by gently moving the toner layer before the developing blade restricts it. This preliminary movement prevents toner from sticking to the roller surface, allowing the subsequent restriction by the developing blade to proceed effectively without excessive mechanical rubbing.

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If a stripping member such as fur brush or sponge roller is brought into contact with the developing roller to strip toner, then toner sticking is reduced, but physical properties of toner change due to peeled or buried external additive, causing charge amount decrease and fogging

Engineering Contradiction:

Improvetoner stripping performanceVSAvoidtoner charge amount stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces the conventional mechanical stripping action (fur brush or sponge roller rubbing the toner) with a gentler moving member that gently moves the toner layer without significant mechanical rubbing. This substitution maintains toner charge stability while still preventing sticking.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operational parameters of the moving member by positioning it at a magnetic pole position where the magnetic field is strong, causing the moving member to gently move the toner layer through magnetic interaction rather than mechanical rubbing. This parameter change reduces toner degradation and maintains charge amount.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If the moving member is positioned at an interpole region to improve cleaning performance, then toner stripping is improved, but toner charge amount decreases causing fogging

Engineering Contradiction:

Improvecleaning performanceVSAvoidtoner charge amount

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

Instead of positioning the moving member at the conventional interpole region, the patent inverts the approach by positioning it at a magnetic pole position where the magnetic field is strong. This inversion allows the moving member to gently move the toner layer through magnetic interaction, achieving both cleaning and charge amount maintenance.

Inventive Principle:

Principle #13The other way round (Inversion)

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 reduces toner sticking to the developing roller, maintains high charge levels, and prevents fogging and density issues, enhancing image quality and the longevity of the toner layer.

Implementation Method 1

a magnet roller having a plurality of magnetic poles

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

magnetic developer carried by the developer bearing member

Methodology Applied

Scientific EffectMagnetism: Magnetism

Implementation Method 3

the moving member being brought into contact with a surface of the developer bearing member, the moved developer being on the developer bearing member after the moving member moved the developer on the developer bearing member

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS10942470B2Developing apparatus, process cartridge, and image forming apparatus

Publication Date: 2021.03.09 CANON KK

AI summary

A developing apparatus, includes: a developer bearing member that encloses a magnet roller having a plurality of magnetic poles and is rotatable; a wall that forms a developer storing chamber for storing a magnetic developer therein; a restricting member configured to restrict a layer thickness of the magnetic developer carried by the developer bearing member; and a moving member configured to move the magnetic developer carried by the developer bearing member before the magnetic developer is restricted by the restricting member, the moving member being brought into contact with a surface of the developer bearing member, the moved developer being on the developer veering member after the moving member moved the developer on the developer bearing member, wherein the moving member is disposed at a position opposed to any of the magnetic pole positions of the plurality of magnetic poles.