Fuser Sliding Surface Roughness for Lubricant Retention

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Solution Overview

Problem

Existing fixing devices suffer from scratches on the inner circumferential surface of the second rotatable member due to the irregularities in the sliding surface of the sliding member, leading to lubricant retention issues and increased wear and rotational torque.

Innovation Solution

The sliding member is designed with a surface roughness Ra1 of 0.20 µm or more and a material ratio Rmr of 35% or more, featuring a glass layer with controlled irregularities to minimize scratches and enhance lubricant retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the sliding surface of the sliding member is made irregular to retain lubricant, then lubricant retention is improved, but scratches occur on the inner circumferential surface of the second rotatable member

Engineering Contradiction:
Improvelubricant retentionVSAvoid scratches on inner circumferential surface
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by precisely controlling the surface roughness (Ra: 0.03-0.50 μm) and material ratio (Rmr: 20-80%) of the sliding surface. This optimization balances lubricant retention capability with scratch prevention, resolving the contradiction between reliability and harmful effects.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by creating specific irregularities only on the sliding surface of the sliding member with controlled roughness characteristics, while keeping other surfaces smooth. This localized treatment retains lubricant where needed without causing scratches on the second rotatable member.

Inventive Principle:
Principle #3Local quality

2Reliability

If the surface roughness of the sliding member is increased to retain lubricant, then lubricant retention is improved, but wear and rotational torque increase

Engineering Contradiction:
Improvelubricant retentionVSAvoidwear and rotational torque
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent optimizes surface roughness parameters (Ra: 0.03-0.50 μm, Rmr: 20-80%) to achieve the minimum necessary irregularity for lubricant retention while minimizing wear and rotational torque. This precise parameter control resolves the contradiction between reliability and substance loss.

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 design reduces scratches on the inner circumferential surface of the second rotatable member, improves lubricant retention, and decreases wear and rotational torque, enhancing the performance of the fixing device.

Implementation Method 1

a sliding member interposed between the inner circumferential surface of the second rotatable member and the pressing member; and a lubricant interposed between the inner circumferential surface of the second rotatable member and the sliding member, wherein the sliding member has an irregular sliding surface

Methodology Applied
Scientific EffectSurface roughness retention: Lubrication

Data Source

PatentEP4579356B1Fixing device and image forming apparatus
Publication Date: 2026.03.18 FUJIFILM BUSINESS INNOVATION CORP
  • EP4579356B1 patent drawingFigure 1
  • EP4579356B1 patent drawingFigure 2
  • EP4579356B1 patent drawingFigure 3

AI summary

A fixing device includes: a first rotatable member; a second rotatable member disposed in contact with the first rotatable member; a pressing member that is disposed along an inner circumferential surface of the second rotatable member and presses the inner circumferential surface of the second rotatable member such that the second rotatable member is pressed against the first rotatable member; a sliding member interposed between the inner circumferential surface of the second rotatable member and the pressing member; and a lubricant interposed between the inner circumferential surface of the second rotatable member and the sliding member. The sliding member has an irregular sliding surface having a surface roughness Ra1 of 0.20 µm or more and a material ratio Rmr of 35% or more.