Fixing Belt Heating Device with PTC Elements for Uniform Temperature

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Solution Overview

Problem

Existing heating devices in image forming apparatuses face challenges in maintaining uniform temperature across the fixing belt, leading to increased heat load and reduced lifespan due to differences in sheet sizes, particularly with non-sheet-pass-through ranges being overheated.

Innovation Solution

A heating device incorporating a rotating belt with resistance heating elements and positive temperature coefficient (PTC) elements connected in series, supported by a heat-conductive metal layer and heat-resistant metal layers, where PTC elements are disposed upstream of resistance heating elements, allowing for temperature regulation and heat conduction suppression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If heating elements are used to heat the fixing belt, then the temperature required for fixing is achieved, but non-sheet-pass-through ranges become overheated causing increased heat load and reduced component lifespan

Engineering Contradiction:

Improvefixing belt temperatureVSAvoidheat load

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The heating belt is divided into multiple heating zones with independent control, allowing each zone to be heated only when needed for sheet passing, preventing overheating in non-sheet-pass-through ranges and reducing overall heat load

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The heating elements operate periodically based on sheet detection, activating only when a sheet is present and deactivating when no sheet is detected, thereby avoiding continuous overheating and reducing energy loss

Inventive Principle:

Principle #19Periodic action

2Temperature

If heating elements are used to maintain fixing temperature, then fixing function is achieved, but temperature uniformity across the fixing belt deteriorates

Engineering Contradiction:

Improvefixing temperatureVSAvoidtemperature uniformity

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

The fixing belt heating system is segmented into multiple independent heating zones, each controlled separately to ensure uniform temperature distribution across the entire belt width and length, preventing hot spots and cold spots

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each heating zone is independently controlled based on local temperature requirements and sheet presence detection, allowing precise temperature management in different regions of the fixing belt to maintain overall temperature uniformity

Inventive Principle:

Principle #3Local quality

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 reduces the temperature of non-sheet-pass-through ranges, minimizing heat load and extending the lifespan of components by maintaining uniform temperature and efficient heat distribution across the fixing belt.

Implementation Method 1

plural resistance elements that have positive temperature coefficients and that are connected to the plural heating elements such that each of the plural resistance elements is connected in series with a corresponding one of the plural heating elements

Methodology Applied

Scientific EffectPositive temperature coefficient: Thermistor

Implementation Method 2

a base material that includes a heat-conductive metal layer and a pair of heat-resistant metal layers between which the heat-conductive metal layer is interposed

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Data Source

PatentUS20170010567A1Heating device, fixing device, image forming apparatus, and base material for heating device

Publication Date: 2017.01.12 FUJIFILM BUSINESS INNOVATION CORP

AI summary

A heating device includes a belt member that is rotated, plural heating elements that are arranged in a width direction of the belt member and generate heat so as to heat the belt member, plural resistance elements that have positive temperature coefficients and are connected to the plural heating elements such that each of the plural resistance elements is connected in series with a corresponding one of the plural heating elements, and a base material that includes a heat-conductive metal layer and a pair of heat-resistant metal layers between which the heat-conductive metal layer is interposed and has a surface on which the plural heating elements and the plural resistance elements are disposed. A temperature of the belt member is reduced by an increase in resistances of the plural resistance elements caused by an increase in temperatures of the plural resistance elements.