Developing Roller Speed Differential for Toner Removal

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In cleanerless image forming apparatuses, melted toner adheres to the photosensitive drum, causing image defects like white streaks and premature deterioration of the developer, as existing solutions fail to adequately address toner removal without applying excessive force.

Innovation Solution

An image forming apparatus with a control unit that adjusts the developing voltage and supply voltage to enhance the cleaning force and reduce developer supply during a dedicated cleaning operation, utilizing a developing roller with a different rotation speed than the photosensitive drum to scrape off adhered toner effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a stronger force is applied in the developing portion to remove melted toner from the photosensitive drum, then toner removal effectiveness is improved, but the photosensitive drum is excessively rubbed causing developer deterioration

Engineering Contradiction:

Improvetoner removal effectivenessVSAvoiddeveloper deterioration

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The developing roller rotates at a different speed than the photosensitive drum, creating a dynamic speed differential that enhances toner scraping capability. This dynamic operation allows effective toner removal while controlling contact pressure to prevent excessive developer deterioration

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the operational parameters by rotating the developing roller at a speed different from the photosensitive drum, creating a speed differential parameter that enhances cleaning effectiveness without requiring excessive force that would deteriorate the developer

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the surface layer of the developing roller is exposed from the toner layer to scrape the photosensitive drum, then toner removal capability is improved, but the photosensitive drum surface is damaged more quickly

Engineering Contradiction:

Improvetoner removal capabilityVSAvoidphotosensitive drum lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

By rotating the developing roller at a different speed than the photosensitive drum, the invention creates a dynamic scraping action that removes toner effectively while the speed differential controls the contact duration and intensity, preventing excessive wear on the photosensitive drum surface

Inventive Principle:

Principle #15Dynamics

3Device complexity

If untransferred toner and fogging toner directly enter between the photosensitive drum and charging roller, then the cleanerless structure is maintained, but stress is generated and melted toner adheres to the photosensitive drum

Engineering Contradiction:

Improvecleanerless structureVSAvoidtoner adhesion and stress

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The invention converts the potentially harmful direct contact of untransferred toner into a beneficial cleaning opportunity. The developing roller, rotating at a different speed, actively scrapes and removes toner that would otherwise adhere to the photosensitive drum, transforming a harmful effect into a useful cleaning function

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The developing roller acts as an intermediary between the untransferred toner and the photosensitive drum. Instead of allowing toner to directly adhere to the drum, the developing roller intercepts and removes the toner through its differential rotation, serving as a protective mediator

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Prevents toner adhesion on the photosensitive drum, maintaining image quality and extending developer lifespan by ensuring effective toner removal without excessive wear.

Implementation Method 1

the developing roller... rotates at a rotation speed different from a rotation speed of the image bearing member... scrape off the melted toner adhered to the photosensitive drum

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

a developing voltage-applying unit configured to apply developing voltage to the developing member; a supply voltage-applying unit configured to apply supply voltage to the developer supply member

Methodology Applied

Scientific EffectElectrical voltage application: Electric Field

Data Source

PatentUS11650515B2Image forming apparatus

Publication Date: 2023.05.16 CANON KK

AI summary

Provided is an image forming apparatus, including: an image bearing member; an exposure unit; a developing member which is rotatable at a rotation speed different from the image bearing member; a developer supply member; a developing voltage-applying unit; a supply voltage-applying unit; and a control unit. The control unit controls execution of: an image forming operation in which a developer image is formed by supplying developer on the image bearing member; and a cleaning operation which removes a substance adhered to the image bearing member using the developing member. In the cleaning operation, the control unit controls the developing voltage-applying unit or the supply voltage-applying unit so that the cleaning force using the developing member becomes stronger than that in the image forming operation.