Fixing Unit Lubricant Composition and Surface Texture

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Solution Overview

Problem

Existing fixing units face issues with lubricant maintenance, leading to sliding layer deterioration, which causes image defects and film deformation due to base oil evaporation or extrusion, and thermal conduction obstruction by thickening agents, resulting in fixing failures.

Innovation Solution

A fixing unit design with a rotary member and a lubricant composed of 80% base oil, applied between the rotary member and a contact portion, featuring a developed interfacial area ratio of 0.10 to 0.50, ensuring stable slidability and lubricant retention through capillary action in the rotary member's minute roughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If the amount of lubricant application is increased to maintain sliding layer for long period, then slidability is improved, but thermal conduction is prevented by thickening agent causing fixing failures

Engineering Contradiction:

Improvesliding layer maintenance periodVSAvoidfixing operation reliability

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the lubricant by specifying base oil content at 80% or more and restricting thickening agent content to 5% or less. This parameter optimization allows sufficient lubricant application without excessive thickening agent that would block thermal conduction, thereby maintaining both long-term slidability and fixing reliability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent adopts a conventional lubricant formulation (base oil and thickening agent combination) but optimizes the ratio parameters to resolve the contradiction. By copying the effective lubricant structure while adjusting composition ratios, the patent achieves both adequate lubrication and thermal conduction without inventing a completely new lubricant system.

Inventive Principle:

Principle #26Copying

2Quantity of substance

If the base oil ratio in lubricant is increased to reduce viscosity, then lubricant flowability is improved, but base oil flows out of lubricated area failing to maintain sliding layer

Engineering Contradiction:

Improvebase oil contentVSAvoidsliding layer maintenance period

Core Design Contradiction:

Quantity of substanceVSDuration of action of moving object

Solution Approach 1:

The patent optimizes the base oil content parameter to 80% or more while simultaneously controlling thickening agent content at 5% or less. This balanced parameter setting ensures the lubricant has low enough viscosity to prevent base oil leakage while maintaining sufficient base oil quantity to form a stable sliding layer for extended periods.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If thickening agent is used in lubricant to maintain viscosity, then lubricant retention is improved, but thermal conduction is obstructed causing fixing failures

Engineering Contradiction:

Improvethickening agent contentVSAvoidthermal conduction efficiency

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent significantly reduces the thickening agent content parameter to 5% or less while maintaining base oil content at 80% or more. This parameter change ensures the lubricant retains sufficient viscosity for base oil retention without excessive thickening agent that would obstruct thermal conduction paths between the heater and recording material.

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

Maintains a stable sliding layer for a long period, preventing image defects and deformation, while allowing effective thermal conduction, thus ensuring reliable fixing operations.

Implementation Method 1

friction is reduced by the base oil forming an oil layer, i.e., sliding layer, at an interface between objects that slide against each other

Methodology Applied

Scientific EffectFriction reduction by base oil forming sliding layer: Lubrication

Implementation Method 2

a lubricant is applied between the inner surface of the rotary member and the contact portion... a developed interfacial area ratio of the inner surface of the rotary member is 0.10 or more and 0.50 or less

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 3

a heating portion configured to heat the rotary member such that the rotary member heats an image on a recording material being nipped

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS20250244701A1Fixing unit and image forming apparatus

Publication Date: 2025.07.31 CANON KK

AI summary

A fixing unit includes a rotary member, a contact portion arranged in an internal space of the rotary member, a pressing member configured to be in contact with an outer surface of the rotary member, and a heating portion configured to heat the rotary member such that the rotary member heats an image on a recording material being nipped in and conveyed through a nip portion between the rotary member and the pressing member. A lubricant is applied between the inner surface of the rotary member and the contact portion. The lubricant contains abase oil at a ratio of 80% or more with respect to a total mass of the lubricant. A developed interfacial area ratio of the inner surface of the rotary member is 0.10 or more and 0.50 or less.