Transfer-separation Device with Repulsive Roller for Abnormal Discharge Prevention

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Solution Overview

Problem

In image forming apparatuses using intermediate transfer belts, electroconductive foreign matter can cause abnormal discharge and lead to maintenance issues due to being fixed in insulating resin, resulting in increased labor costs and environmental impact.

Innovation Solution

A transfer-separation device with a repulsive roller having a higher volume resistance than the secondary transfer roller and a surface resistance of the secondary transfer roller set to 106.5 ohms or higher, which prevents abnormal discharge by ensuring the current applied to the repulsive roller remains a transfer current, and a charge-eliminating/separating member that eliminates charges without interfering with the transfer current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a constant current is supplied to the secondary transfer roller to obtain stable transfer performance, then transfer stability is improved, but in high-humidity environments the recording medium resistance decreases causing current leakage and transfer performance degradation

Engineering Contradiction:

Improvetransfer performance stabilityVSAvoidcurrent leakage via recording medium

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a repulsive roller as an intermediary component between the secondary transfer roller and the intermediate transfer belt. This repulsive roller has higher volume resistance than the secondary transfer roller, creating an additional resistance barrier that prevents current leakage through the recording medium while maintaining the necessary transfer electric field.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the resistance parameters of the transfer system components. Specifically, the secondary transfer roller is designed with surface resistance of 10^6.5 ohms or higher, and the repulsive roller has volume resistance greater than the secondary transfer roller. These parameter changes ensure that the transfer current remains stable and does not leak through the recording medium even in high-humidity environments.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If electroconductive foreign matter adheres to the recording medium and enters the space between the charge eliminating member and secondary transfer roller, then abnormal discharge occurs and foreign matter becomes fixed in resin, but this increases maintenance labor costs and environmental impact

Engineering Contradiction:

Improveabnormal discharge preventionVSAvoidmaintenance cost and environmental impact

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies preliminary anti-action by designing the charge eliminating member and separation member to operate at controlled potentials that prevent abnormal discharge before it can occur. The repulsive roller and secondary transfer roller resistance configuration creates a potential barrier that stops electroconductive foreign matter from causing abnormal discharge and becoming fixed in the resin structure.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent converts the potentially harmful effect of electroconductive foreign matter into a beneficial outcome by using the resistance characteristics of the repulsive and secondary transfer rollers. The high resistance values ensure that even if foreign matter is present, the electric field configuration prevents abnormal discharge, thereby eliminating maintenance issues and environmental problems.

Inventive Principle:

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

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

Stabilizes the transfer ratio and prevents abnormal discharge, reducing maintenance needs and environmental impact by ensuring the foreign matter is not fixed in the resin, thus maintaining efficient operation.

Implementation Method 1

a transfer bias having the same polarity as that of a toner image is applied to the repulsive roller 16 to transfer the toner image onto the recording medium S from the intermediate transfer belt 11

Methodology Applied

Scientific EffectElectrostatic transfer: Electrostatics

Implementation Method 2

a charge eliminating member 23 that eliminates charges from a surface of the recording medium S to separate the recording medium S from the intermediate transfer belt 11

Methodology Applied

Scientific EffectCharge elimination: Electrostatic Discharge

Data Source

PatentUS7773928B2Transfer-separation device and image forming apparatus

Publication Date: 2010.08.10 RICOH CO LTD

AI summary

A transfer-separation device includes an intermediate transfer unit, a secondary transfer roller, a repulsive roller, a transfer unit, and a charge-eliminating/separating member. The secondary transfer roller and the repulsive roller form a nip through which the intermediate transfer unit and a recording medium pass. The transfer unit applies a bias voltage of a polarity identical to that of a toner image to the repulsive roller to secondarily transfer the toner image onto the recording medium. The charge-eliminating/separating member separates the recording medium from the intermediate transfer unit by removing charge therefrom. The volume resistance of the repulsive roller is greater than that of the secondary transfer roller. The surface resistance of the secondary transfer roller is equal to or greater than 106.5 ohm.