Fixing Rotator Surface Layer Structure for Wrinkle-Free Fusing

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Solution Overview

Problem

Existing fixing rotators in electrophotographic image forming apparatuses suffer from 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, restricting material selection and causing gloss unevenness and reduced followability.

Innovation Solution

A fixing rotator with a composite structure comprising an endless base layer, an elastic layer, and a surface layer, where the internal stress of the surface layer is controlled to not exceed −3.0% to prevent wrinkling, allowing for a wide range of materials and maintaining heat conductivity and followability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If thermal shrinkage is imparted to fluororesin tubes to reduce wrinkling, then surface layer wrinkling is reduced, but manufacturing cost increases and material selection is restricted

Engineering Contradiction:

Improvesurface layer wrinkling resistanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter by specifying a fluororesin with a specific melting point range (200°C to 250°C) and controlling the crystallinity ratio (30% to 70%). This parameter control allows the fluororesin to exhibit appropriate thermal expansion characteristics without requiring thermal shrinkage processing, thereby reducing manufacturing cost while preventing surface layer wrinkling.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite structure consisting of a base layer, elastic layer, and surface layer made of fluororesin. The fluororesin surface layer is specifically designed with controlled crystallinity and melting characteristics to work synergistically with the elastic layer, achieving wrinkling prevention without additional processing steps.

Inventive Principle:

Principle #40Composite materials

2Reliability

If thermal shrinkage is imparted to fluororesin tubes to reduce wrinkling, then surface layer wrinkling is reduced, but gloss unevenness occurs and followability deteriorates

Engineering Contradiction:

Improvesurface layer wrinkling resistanceVSAvoidgloss uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent controls the melting point of the fluororesin within 200°C to 250°C and maintains crystallinity between 30% and 70%. These parameter controls ensure that the fluororesin expands appropriately with the elastic layer during heating cycles, preventing both wrinkling and gloss unevenness while maintaining surface smoothness and followability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies different properties to different layers: the surface layer uses fluororesin with specific crystallinity for smoothness and non-stick properties, while the elastic layer provides flexibility and followability. This local differentiation of material properties achieves multiple functions simultaneously.

Inventive Principle:

Principle #3Local quality

3Reliability

If the linear expansion rate of the elastic layer is increased to prevent wrinkling, then wrinkling is reduced, but heat conductivity of the elastic layer deteriorates

Engineering Contradiction:

Improvesurface layer wrinkling resistanceVSAvoidheat conductivity

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent creates a composite structure where the fluororesin surface layer with controlled crystallinity (30%-70%) provides appropriate thermal expansion to prevent wrinkling, while the base layer and elastic layer are designed to maintain heat conductivity. The specific melting point range of the fluororesin (200°C-250°C) ensures it expands with the elastic layer without excessive heat transfer resistance.

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 over extended use, maintains gloss uniformity, and reduces manufacturing costs by allowing material flexibility while ensuring high thermal conductivity and followability.

Implementation Method 1

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

Implementation Method 2

heat transfer filler in the rubber of the elastic layer

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS20250362631A1Fixing rotator, thermal fixing device, and electrophotographic image forming apparatus

Publication Date: 2025.11.27 CANON KK

AI summary

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