Fixing Device IH Heating Magnetic Plate Temperature Control

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Solution Overview

Problem

Existing fixing devices in image forming apparatuses, such as printers and copiers, face challenges in maintaining a consistent heat temperature across the width of the fixing belt during high-speed printing, leading to potential fixing failures due to the deterioration of magnetic characteristics in magnetic shunt alloys at high temperatures, which can cause excessive load on IH driving circuit components.

Innovation Solution

A fixing device design incorporating a conductive layer with a magnetic shunt alloy layer and a magnetic plate, where the magnetic plate generates heat independently of the magnetic shunt alloy, maintaining the fixing belt's temperature and reducing the load on the IH driving circuit by preventing excessive high-frequency current application.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the heat capacity of the fixing belt is set small to save energy consumption, then energy efficiency is improved, but the fixing belt cannot maintain sufficient heat quantity during high-speed printing

Engineering Contradiction:

Improveenergy consumptionVSAvoidheat quantity maintenance

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The fixing belt is constructed as a composite structure with a heat-generating layer containing magnetic powder dispersed in a resin matrix. This composite material enables the belt to generate heat through electromagnetic induction while maintaining appropriate heat capacity for both energy efficiency and sufficient heat quantity during high-speed printing.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If magnetic shunt alloy is used to reduce heat value variation in the width direction, then temperature uniformity is improved, but the magnetic characteristic deteriorates when heated to temperature close to Curie temperature during high-speed printing

Engineering Contradiction:

Improvetemperature uniformityVSAvoidmagnetic characteristic stability

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

Magnetic powder is selectively dispersed only in the heat-generating layer of the fixing belt, concentrating the magnetic properties where heat generation is needed. This local quality approach maintains temperature uniformity across the width direction while preventing bulk magnetic material from reaching Curie temperature and deteriorating its magnetic characteristics.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention changes the physical state and distribution of magnetic material from bulk magnetic shunt alloy to dispersed magnetic powder particles in a resin matrix. This parameter change allows the magnetic material to remain below Curie temperature while still providing sufficient magnetic properties for electromagnetic induction heating and temperature uniformity.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If the IH driving circuit continues to feed high-frequency current to raise the temperature of the fixing belt when magnetic characteristic deteriorates, then temperature maintenance is improved, but the load on elements such as IGBT increases and component breakdown becomes likely

Engineering Contradiction:

Improvefixing belt temperatureVSAvoiddriving circuit component reliability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

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 design ensures consistent heat distribution across the fixing belt, preventing fixing failures and reducing the risk of component breakdown in the IH driving circuit, while maintaining energy efficiency and high-quality image formation.

Implementation Method 1

a fixing device that generates heat in a conductive layer with an electromagnetic induction heating (IH) system

Methodology Applied

Scientific EffectElectromagnetic induction heating (IH): Electromagnetic Induction

Implementation Method 2

generates heat in a conductive layer with an electromagnetic induction heating (IH) system

Methodology Applied

Scientific EffectEddy current heating: Eddy Currents

Implementation Method 3

a magnetic shunt alloy is used to reduce variation of a heat value generated in the width direction of the fixing belt and compensate for a shortage of a heat quantity of the fixing belt

Methodology Applied

Scientific EffectElectromagnetic induction heating: Electromagnetic Induction

Data Source

PatentUS9389558B2Fixing device and image forming apparatus

Publication Date: 2016.07.12 KK TOSHIBA

AI summary

A fixing device includes an endless heat generating section including a conductive layer, an induction-current generating section configured to generate an induction current in the conductive layer, a temperature-sensitive magnetic body present in a position opposed to the induction-current generating section via the heat generating section, and a magnetic plate present in a position opposed to the heat generating section via the temperature-sensitive magnetic body.