Heat Shield with Variable Conductivity for Fixing Rotator

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Solution Overview

Problem

Existing fixing devices in image forming apparatuses face challenges in quickly heating the endless belt or film to shorten print time and overcome heat shortages, while also preventing overheating of axial ends, which can lead to thermal deformation of supports and flanges.

Innovation Solution

The implementation of a heat shield with varying thermal conductivity sections, where a section with decreased conductivity supports the heat shield and an section with increased conductivity abuts it, interposed between the heater and the fixing rotator, to efficiently distribute heat and prevent overheating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a heater is disposed inside an endless belt to heat the belt quickly and shorten print time, then heating speed is improved, but axial ends of the belt are susceptible to overheating

Engineering Contradiction:

Improveprint timeVSAvoidtemperature at axial ends

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The endless belt is divided into a heating section (where the heater is disposed) and non-heating sections (axial ends). This segmentation allows differential thermal management, enabling quick heating where needed while preventing overheating at axial ends through reduced heat exposure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A heat shield is introduced as an intermediary component between the heater and the axial ends of the endless belt. The heat shield blocks excessive heat from reaching the axial ends, preventing overheating while allowing the heating section to receive adequate heat for maintaining productivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If a heat shield is interposed between the heater and the endless belt to prevent overheating, then temperature control is improved, but heating efficiency may be reduced

Engineering Contradiction:

Improvetemperature uniformityVSAvoidheating efficiency

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

The heat shield is positioned selectively only at the axial ends of the endless belt where overheating occurs, rather than covering the entire belt. This local application allows the majority of the belt (the heating section) to receive adequate heat efficiently, maintaining heating efficiency while preventing overheating at specific problematic locations.

Inventive Principle:

Principle #3Local quality

3Productivity

If the endless belt is heated quickly to overcome heat shortage at high speed conveyance, then productivity is improved, but thermal deformation of supports and flanges may occur

Engineering Contradiction:

Improveconveyance speedVSAvoidstructural stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The heat shield acts as a protective intermediary between the heater and the axial ends of the endless belt, blocking excessive thermal energy from reaching the supports and flanges. This prevents thermal deformation of these structural components while allowing the belt to be heated quickly in the heating section to maintain high-speed productivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The endless belt system is segmented into a heating section (exposed to heater) and protected sections (axial ends with heat shield). This segmentation allows differential thermal treatment, enabling quick heating for productivity while protecting structural components from thermal deformation.

Inventive Principle:

Principle #1Segmentation

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 allows for effective heat distribution, reducing the risk of thermal deformation and ensuring consistent fixing performance by shielding the fixing rotator from excessive heat, thus maintaining productivity and image quality.

Implementation Method 1

The heat shield includes a first section supported by the support and having a decreased thermal conductivity and a second section abutting the first section in an axial direction of the heat shield and having an increased thermal conductivity greater than the decreased thermal conductivity of the first section

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a heater disposed opposite the fixing rotator to heat the fixing rotator

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentUS9046839B2Fixing device including a heat shield and image forming apparatus

Publication Date: 2015.06.02 RICOH CO LTD

AI summary

A fixing device includes a fixing rotator rotatable in a predetermined direction of rotation, a heater disposed opposite the fixing rotator to heat the fixing rotator, and an opposed rotator contacting an outer circumferential surface of the fixing rotator. A heat shield interposed between the heater and the fixing rotator shields the fixing rotator from the heater. A support supports the heat shield. The heat shield includes a first section supported by the support and having a decreased thermal conductivity and a second section abutting the first section in an axial direction of the heat shield and having an increased thermal conductivity greater than the decreased thermal conductivity of the first section.