Selective Transfer Roller Switching for Toner Adhesion Prevention

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Solution Overview

Problem

Conventional intermediate transfer-type image forming apparatuses face inefficiencies in cleaning the secondary transfer roller, leading to prolonged printing wait times due to the accumulation of toner, which affects productivity and image quality.

Innovation Solution

The image forming apparatus incorporates a secondary transfer unit with two rollers of different axial lengths, allowing for selective switching based on the width of the recording medium, using a control mechanism to adjust the position of the rollers and apply appropriate transfer voltages to prevent toner adhesion and improve cleaning efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If reverse transfer voltage is applied to clean the secondary transfer roller, then toner adhesion is removed, but printing wait time increases

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidprinting wait time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The elastic layer is configured to naturally release toner through elastic recovery during normal operation, performing cleaning action before toner accumulation becomes problematic, thereby avoiding the need for time-consuming reverse voltage cleaning cycles

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The elastic layer performs self-cleaning through its inherent elastic properties, automatically releasing adhered toner particles without requiring external cleaning mechanisms or reverse voltage application, thus maintaining continuous printing operation without wait time

Inventive Principle:

Principle #25Self-service

2Device complexity

If a single secondary transfer roller is used, then device structure is simple, but toner adhesion accumulates during durable printing

Engineering Contradiction:

Improveroller configurationVSAvoidtoner transfer performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The elastic layer is designed with specific local properties (axial length, elasticity) optimized for toner release, creating a region with enhanced anti-adhesion characteristics at the critical contact zone between the secondary transfer roller and intermediate transfer belt

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The elastic layer's axial length is specifically designed to be shorter than the secondary transfer roller's axial length, creating a parameter difference that enables toner release through elastic deformation while maintaining the overall roller structure

Inventive Principle:

Principle #35Parameter changes

3Reliability

If elastic layer axial length is increased, then toner adhesion prevention is improved, but device size increases

Engineering Contradiction:

Improvetoner release performanceVSAvoidelastic layer axial length

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The elastic layer's axial length is precisely controlled to be shorter than the secondary transfer roller's axial length, optimizing the balance between toner release performance and device compactness by creating an elastic deformation zone without excessive dimensional increase

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 solution reduces printing wait times and enhances productivity by effectively preventing toner adhesion on the secondary transfer roller, ensuring efficient image transfer and maintaining high image quality without the need for prolonged cleaning processes.

Implementation Method 1

an elastic layer laid around the outer circumferential face of the metal shaft to form a transfer nip by keeping the elastic layer in pressed contact with the image carrying member

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The transfer voltage power supply applies a voltage to the transfer roller

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentUS11474457B2Image forming apparatus that can selectively switch between two transfer rollers

Publication Date: 2022.10.18 KYOCERA DOCUMENT SOLUTIONS INC

AI summary

An image forming apparatus includes an image forming portion, an image input portion, a transfer unit, a transfer voltage power supply, and a control portion. The transfer unit includes a transfer roller having a metal shaft and an elastic layer laid around an outer circumferential face of the metal shaft to form a transfer nip by keeping the elastic layer in pressed contact with an image carrying member, and transfers a toner image formed on the image carrying member to a recording medium as it passes through the transfer nip. The transfer unit includes, as the transfer roller, a first roller, and a second roller having a larger axial-size elastic layer compared to the first roller. The control portion arranges the first or second roller opposite the image carrying member according to width-direction sizes of the recording medium and image data fed to the image input portion.