Fuser Heater Support Openings to Prevent Overheating

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Solution Overview

Problem

Existing fixing devices in electrophotographic image forming apparatuses suffer from excessive temperature rise due to inadequate heat radiation, leading to potential overheating of the heater and reduced reliability.

Innovation Solution

The fixing device incorporates a cylindrical fixing member with a heater tube having a partially exposed sealing portion, a reflector to reflect radiant heat, and a support member with openings to facilitate heat dissipation, preventing overheating and improving thermal efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a support member is arranged around the heater to block heat radiation, then heat retention is improved, but the heater temperature rises excessively causing overheating

Engineering Contradiction:
Improveheat retentionVSAvoidheater temperature
Core Design Contradiction:
Use of energy by moving objectVSTemperature

Solution Approach 1:

The support member is designed with a through-hole that selectively allows heat radiation to pass through while maintaining structural support function. This local modification creates different thermal properties in different regions of the support member, allowing it to both retain heat and prevent overheating simultaneously

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

A through-hole is extracted from the support member to remove the problematic heat-blocking function from the specific region where it causes overheating, while preserving the support function. This extraction allows heat to escape from the heater area without compromising the overall structural integrity

Inventive Principle:
Principle #2Taking out (Extraction)

2Strength

If the sealing portion of the heater is completely covered by the support member, then structural support is improved, but heat dissipation is hindered causing energy wastage

Engineering Contradiction:
Improvestructural supportVSAvoidenergy wastage
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The support member features a through-hole that creates a local opening specifically for heat dissipation while maintaining structural support in other regions. This local quality differentiation allows the same component to serve both structural and thermal management functions

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The support member is designed to perform multiple functions simultaneously: providing structural support for the heater and facilitating heat dissipation through the through-hole. This multi-functionality eliminates the need for separate components and resolves the contradiction between structural integrity and heat management

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 configuration effectively prevents overheating of the heater, enhances reliability, and reduces energy wastage by optimizing heat distribution and dissipation, suitable for small image forming apparatuses without additional cooling mechanisms.

Implementation Method 1

a heater (23) disposed inside a loop of the fixing member (21)... a heat generator accommodated in the tube

Methodology Applied
Scientific EffectResistive heating: Joule Heating

Implementation Method 2

a reflector to reflect radiant heat

Methodology Applied
Scientific EffectRadiant heat reflection: Reflection

Implementation Method 3

a support member with openings to facilitate heat dissipation

Methodology Applied
Scientific EffectHeat dissipation: Convection

Data Source

PatentEP3709094B1Fixing device and image forming apparatus incorporating same
Publication Date: 2026.01.07 RICOH CO LTD
  • EP3709094B1 patent drawingFigure 1~2
  • EP3709094B1 patent drawingFigure 3
  • EP3709094B1 patent drawingFigure 4~6

AI summary

A fixing device (5) includes a fixing member (21) in a cylindrical shape, an opposite member (22) disposed opposite an outer surface of the fixing member (21), a nip formation member (24) disposed inside a loop of the fixing member (21), a support member (25) disposed inside the loop of the fixing member (21) and configured to support the nip formation member (24), and a heater (23) disposed inside the loop of the fixing member (21). The nip formation member (24) sandwiches the fixing member (21) between the nip formation member (24) and the opposite member (22) and forms a nip between the nip formation member (24) and the opposite member (22). The heater (23) includes a tube (40) having a sealing portion (40a) at least partially exposed out of the support member (25) and a heat generator (41) accommodated in the tube (40).