Segmented Heating Members for Uniform Fixing Temperature

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Solution Overview

Problem

In image forming apparatuses, it is challenging to optimize thermal efficiency and maintain uniform heating across the fixing device, leading to issues such as uneven heating, warpage of elements, and reduced fixing quality, especially in color printing, due to the diffusion of heat energy and low heat capacity of fixing elements.

Innovation Solution

A fixing device with a configuration of plate-shaped heating members, an endless belt with an elastic layer, and a press roller, where the heating members are strategically arranged and electrically controlled to heat only the necessary region, minimizing energy consumption and preventing temperature non-uniformity by optimizing the creepage and space distances between heat generating members.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If heat capacity of fixing elements is reduced to maximize thermal efficiency, then energy consumption is reduced, but temperature uniformity deteriorates causing uneven heating

Engineering Contradiction:
Improveenergy consumptionVSAvoidtemperature uniformity
Core Design Contradiction:
Use of energy by moving objectVSTemperature

Solution Approach 1:

The heating element is divided into multiple independent heating sections (first heating section and second heating section) that can be controlled separately. This allows selective heating of only the regions where sheets pass, reducing overall energy consumption while maintaining temperature uniformity in the active heating zones through independent control.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the heating element have different thermal characteristics - the first heating section has higher heat capacity than the second heating section. This local differentiation allows the first section to maintain temperature uniformity while the second section provides rapid heating response, collectively solving the temperature uniformity problem while minimizing energy waste in non-active regions.

Inventive Principle:
Principle #3Local quality

2Temperature

If heating is applied to entire fixing device region, then temperature uniformity is improved, but energy consumption increases due to heating of non-sheet passing portions

Engineering Contradiction:
Improvetemperature uniformityVSAvoidenergy consumption
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The heating element is segmented into multiple independently controllable heating sections. By activating only the heating sections corresponding to sheet passing regions and keeping other sections inactive, the system achieves temperature uniformity where needed while avoiding energy waste in non-active regions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The heating sections are dynamically controlled based on sheet detection - when a sheet is detected, the corresponding heating sections are activated; when no sheet is present, they are deactivated. This dynamic adjustment optimizes energy consumption while maintaining temperature uniformity during active heating periods.

Inventive Principle:
Principle #15Dynamics

3Productivity

If heat capacity is minimized for thermal efficiency, then fixing speed is improved, but temperature stability deteriorates causing warpage and element deterioration

Engineering Contradiction:
Improvefixing speedVSAvoidtemperature stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The heating element is divided into sections with different heat capacities - the first heating section has higher heat capacity for temperature stability, while the second has lower heat capacity for rapid response. This segmentation allows the system to achieve both fixing speed and temperature stability simultaneously.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system changes thermal parameters by using heating sections with different heat capacities in different positions. The first heating section's higher heat capacity provides temperature stability to prevent warpage, while the overall minimized heat capacity of the fixing elements maintains high fixing speed.

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 solution allows for stable and efficient heating of the sheet passing region, reducing energy consumption while maintaining high fixing quality by ensuring uniform temperature distribution and preventing wasteful heating of non-sheet passing portions.

Implementation Method 1

a configuration of plate-shaped heating members, an endless belt with an elastic layer, and a press roller, where the heating members are strategically arranged and electrically controlled to heat only the necessary region

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

A fixing device mounted on an image forming apparatus typically employs a lamp that emits infrared rays, such as a halogen lamp, or an induction heating unit that generates heat by electromagnetic induction as a heat source for fixing an image to an imaging medium

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

A fixing device mounted on an image forming apparatus typically employs a lamp that emits infrared rays, such as a halogen lamp

Methodology Applied
Scientific EffectInfrared radiation: Infrared Radiation

Data Source

PatentEP3001254B1Fixing device and image forming apparatus
Publication Date: 2021.11.17 TOSHIBA TEC KK
  • EP3001254B1 patent drawingFigure 1
  • EP3001254B1 patent drawingFigure 2~3
  • EP3001254B1 patent drawingFigure 4~5

AI summary

A fixing device includes a roller, an endless belt, and a heat generating member disposed in a space inside the endless belt, extending in a width direction of the endless belt, and pressing the endless belt against the roller. A sheet is passed through a nip formed between the roller and a portion of the endless belt pressed by the heat generating member, such that an image on the sheet is fixed thereto. The heat generating member includes first and second heat generating portions that are adjacent to each other along the width direction and independently operable from each other. A boundary of the first and second heat generating portions extends in a direction inclined with respect to a sheet conveying direction.