Fixing Rotator Structure for Wrinkle-Resistant Thermal Fusing

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Solution Overview

Problem

Existing fixing rotators in electrophotographic image forming apparatuses face issues with surface layer wrinkling due to thermal expansion and shrinkage, leading to image defects and increased manufacturing costs when thermal shrinkage is imparted to fluororesin tubes, which also affect followability and heat conductivity.

Innovation Solution

A fixing rotator with a composite structure of a base layer, elastic layer, and surface layer, where the elastic layer includes silicone rubber and thermally conductive filler, aligned in the thickness direction through an electric field, to manage thermal expansion and reduce wrinkling without material restrictions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If thermal shrinkage is imparted to fluororesin tube to reduce wrinkling, then wrinkling resistance is improved, but manufacturing cost increases and material selection is restricted

Engineering Contradiction:
Improvewrinkling resistanceVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter from fluororesin to silicone rubber, which inherently provides different thermal expansion characteristics. This material substitution eliminates the need for thermal shrinkage processing while achieving wrinkling resistance, thereby reducing manufacturing complexity and cost.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure by filling thermally conductive filler particles into silicone rubber. This composite material achieves both the desired thermal expansion properties to prevent wrinkling and maintains manufacturing simplicity without requiring thermal shrinkage processing.

Inventive Principle:
Principle #40Composite materials

2Reliability

If thermal shrinkage is imparted to fluororesin tube to reduce wrinkling, then wrinkling resistance is improved, but apparent hardness increases and followability deteriorates

Engineering Contradiction:
Improvewrinkling resistanceVSAvoidfollowability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the base material from fluororesin to silicone rubber, which has inherently different mechanical and thermal properties. This material parameter change provides wrinkling resistance through controlled thermal expansion while maintaining softness and flexibility for good followability, eliminating the need for thermal shrinkage that would increase hardness.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent achieves different properties in different aspects: the silicone rubber base provides softness and followability, while the thermally conductive filler provides thermal expansion control for wrinkling resistance. This local quality differentiation allows simultaneous achievement of good followability and wrinkling resistance without thermal shrinkage processing.

Inventive Principle:
Principle #3Local quality

3Ease of operation

If heat transfer filler amount is reduced to increase linear expansion rate, then followability is improved, but heat conductivity deteriorates

Engineering Contradiction:
ImprovefollowabilityVSAvoidheat conductivity
Core Design Contradiction:
Ease of operationVSTemperature

Solution Approach 1:

The patent changes the base material from rubber to silicone rubber, which has inherently higher linear expansion rate. This allows maintaining good followability while achieving sufficient heat conductivity through the silicone rubber matrix itself, reducing the dependency on large amounts of heat transfer filler.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material where thermally conductive filler is dispersed in silicone rubber. The silicone rubber base provides both the necessary linear expansion for followability and baseline heat conductivity, while the filler enhances heat transfer. This composite structure achieves both good followability and heat conductivity with optimized filler content.

Inventive Principle:
Principle #40Composite materials

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

The solution effectively prevents wrinkling and maintains heat conductivity, ensuring long-term performance and image quality without increasing manufacturing costs or hardness, while allowing flexibility to uneven media.

Implementation Method 1

the elastic layer includes silicone rubber and thermally conductive filler, aligned in the thickness direction through an electric field, to manage thermal expansion and reduce wrinkling

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the elastic layer includes silicone rubber and thermally conductive filler, aligned in the thickness direction through an electric field

Methodology Applied
Scientific EffectElectric field alignment: Electric Field

Implementation Method 3

the thermal expansion and shrinkage of the tube material are repeated according to repetition of the heat cycle, and the tension of the fluororesin tube gradually loosens

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP4657175A1Fixing rotator, thermal fixing device, and electrophotographic image forming apparatus
Publication Date: 2025.12.03 CANON KK
  • EP4657175A1 patent drawingFigure 1.
  • EP4657175A1 patent drawingFigure 2
  • EP4657175A1 patent drawingFigure 3

AI summary

A fixing rotator (41) including an endless shaped base layer (41d), an elastic layer (41c) at an outer peripheral surface side of the base layer (41d), and a surface layer (41a) fixed to an outer peripheral surface side of the elastic layer (41c) via an adhesive layer (41b), wherein an internal stress B of a sample taken from the surface layer (41a), as represented by a specific formula, is -3.0% or less.