Charging Roller Surface Texture for Toner Contamination Control

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Solution Overview

Problem

Existing image forming apparatuses face challenges in maintaining stable charging characteristics and preventing contamination of photoreceptors, while also ensuring effective cleaning of toner residues, particularly due to surface unevenness and contamination issues with charging rollers and cleaning blades.

Innovation Solution

The apparatus incorporates a charging member with surface unevenness created by projections and recesses extending in the direction of rotation, and a cleaning blade configured to abrade projections on the photoreceptor, forming a process cartridge that includes these components for improved charging and cleaning performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a charging roller with a smooth surface is used, then good initial charging characteristics are achieved, but toner contamination occurs on the surface over time

Engineering Contradiction:

Improvecharging characteristics stabilityVSAvoidtoner contamination

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The charging roller surface is designed with local quality variation through projections and recesses. The projections provide contact points for charging while the recesses prevent toner accumulation. This local differentiation allows the surface to maintain good charging characteristics while resisting toner contamination.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The charging roller surface is segmented into discrete projections and recesses rather than being smooth or uniformly textured. This segmentation allows toner to pass through the recesses without adhering to the surface, while the projections maintain effective charging contact with the photoreceptor.

Inventive Principle:

Principle #1Segmentation

2Reliability

If a cleaning blade is made harder to effectively remove toner, then cleaning performance improves, but damage to the photoreceptor surface increases

Engineering Contradiction:

Improvecleaning performanceVSAvoidphotoreceptor surface damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The cleaning blade uses a soft material with specific physical parameters (JIS A 60-70 degree hardness) that balances cleaning effectiveness with photoreceptor protection. The material parameters are carefully selected to enable toner removal through adhesion and abrasion without causing excessive surface damage.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The cleaning blade is constructed from composite or specially formulated elastomeric materials that combine cleaning effectiveness with gentleness to the photoreceptor surface. The material composition is designed to provide optimal friction and adhesion properties for toner removal while minimizing damage.

Inventive Principle:

Principle #40Composite materials

3Productivity

If the cleaning blade pressure is increased to improve toner removal, then cleaning effectiveness improves, but abrasion of the photoreceptor surface increases

Engineering Contradiction:

Improvetoner removal efficiencyVSAvoidphotoreceptor operational life

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The pressing force parameters are optimized to a specific range that achieves effective toner removal while controlling photoreceptor abrasion. The pressure is sufficient to enable the cleaning blade material to adhere to and remove toner, but not excessive to cause rapid surface degradation.

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

This configuration maintains stable charging and cleaning performance over time by preventing toner contamination of the charging roller and ensuring effective removal of toner residues from the photoreceptor, extending the operational life of the apparatus.

Implementation Method 1

voltage is applied to a charging device, such as a charging roller including a metal core and a conductive elastic layer overlying the metal core, and the charging roller is disposed in contact with the photoreceptor that rotates

Methodology Applied

Scientific EffectElectrostatic charging: Electrostatics

Implementation Method 2

the cleaning blade is configured to abrade projections formed on the surface of the image bearer

Methodology Applied

Scientific EffectAbrasion: Abrasion

Implementation Method 3

an edge or ridge of the cleaning blade is pressed against the surface of the photoreceptor that rotates, thereby scraping off from the photoreceptor substances, such as toner, adhering thereto

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS9310750B2Image forming apparatus and process cartridge therefor

Publication Date: 2016.04.12 RICOH CO LTD

AI summary

An image forming apparatus includes a rotatable image bearer, a charging member to contact a surface of the image bearer and charge the image bearer, an exposure device to expose the image bearer and form a latent image, a developing device to develop the latent image on the image bearer into a toner image, a transfer device to transfer the toner image from the image bearer onto a transfer medium, and a cleaning blade to contact the surface of the image bearer and remove toner from the image bearer after image transfer. The charging member has surface unevenness created by projections and recesses extending in a direction of rotation of the image bearer. The cleaning blade is configured to abrade projections formed on the surface of the image bearer.