Charge Eliminator Positioning in Heating Device

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Solution Overview

Problem

In fixing devices of image forming apparatuses, the offset phenomenon occurs due to the charging of the pressing roller to a polarity opposite to the toner, leading to issues like electrostatic offset and paper jam.

Innovation Solution

A heating device is designed with a rotator, a heater, a pressurizer, a charge eliminator, and a contact part. The charge eliminator contacts the conductive surface of the pressurizer outside the main heat generating region, and the contact part contacts the rotator at a position corresponding to the charge eliminator's contact area, effectively neutralizing charges and preventing offset.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a non-contact charge eliminating member is arranged with respect to the pressure roller, then the pressure roller is neutralized, but the charge elimination effectiveness is insufficient leading to offset phenomenon

Engineering Contradiction:

Improvecharge neutralization effectivenessVSAvoidoffset phenomenon

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the non-contact charge eliminating member with a contact-type charge eliminating member that directly touches the pressure roller surface. This mechanical contact approach substitutes the ineffective non-contact method, enabling effective charge neutralization by allowing charge transfer through direct physical contact between the charge eliminating member and the pressure roller.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a contact part as an intermediary between the charge eliminating member and the pressure roller. This contact part serves as a mediator that facilitates charge transfer while protecting the charge eliminating member from direct exposure to high-temperature regions, thereby maintaining charge elimination effectiveness without causing offset.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the charge eliminator contacts the pressurizer within the main heat generating region, then charge neutralization is achieved, but the contact part deteriorates due to high temperature

Engineering Contradiction:

Improvecharge neutralizationVSAvoidcontact part lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent applies local quality by positioning the charge eliminator to contact the pressurizer at a specific location outside the main heat generating region. This localized contact arrangement ensures that charge neutralization occurs at a cool region while the main heating function remains uninterrupted, thereby extending the contact part's lifespan by avoiding high-temperature exposure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent resolves the contradiction by changing the spatial dimension of contact - moving the charge elimination contact point from the heated region to a different spatial location (outside the main heat generating region). This dimensional repositioning allows charge neutralization to occur without thermal degradation of the contact part.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Duration of action of stationary object

If the charge eliminator is positioned outside the main heat generating region, then the contact part lifespan is extended, but charge neutralization effectiveness may be reduced

Engineering Contradiction:

Improvecontact part lifespanVSAvoidcharge neutralization effectiveness

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The contact part acts as an intermediary that bridges the charge eliminator and the pressurizer. By positioning this intermediary at a location outside the heat generating region, it maintains both the charge neutralization function and the extended lifespan, as the intermediary material is selected to facilitate charge transfer while being protected from thermal degradation.

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

This configuration effectively prevents the offset phenomenon, maintaining the quality of the printed images and reducing the risk of paper jams by ensuring proper charge neutralization.

Implementation Method 1

a heater (22) including a main heat generating region (D) configured to heat the rotator (20)

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a charge eliminator (37)... effectively neutralizing charges and preventing offset

Methodology Applied

Scientific EffectElectrostatic discharge: Electrostatic Discharge

Data Source

PatentUS20250076797A1Heating device, fixing device, and image forming apparatus

Publication Date: 2025.03.06 RICOH CO LTD

AI summary

A heating device includes a rotator, a heater including a main heat generating region to heat the rotator, a pressurizer including a conductive surface configured to contact the rotator to form a nip therebetween. Further, there is a charge eliminator, a contact part to contact the rotator. The charge eliminator contacts the conductive surface at a portion of the pressurizer, the portion being outside of the main heat generating region in a longitudinal direction of the heater. Further, the contact part contacts the rotator at a position corresponding to the portion in a longitudinal direction of the heater.