Fixing Device Convex Reflector for Efficient Infrared Heating

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Solution Overview

Problem

Existing fixing devices in electrophotographic image forming apparatuses face inefficiencies in heating due to light or heat reflection from reflectors towards heating elements rather than the intended heating targets, leading to decreased heating efficiency and potential discoloration of reflectors.

Innovation Solution

The use of reflectors with convex-shaped reflection surfaces and strategically positioned gaps or through-holes to redirect infrared light towards heating targets, reducing reflections towards heating elements and minimizing heat storage, thereby enhancing heating efficiency and preventing reflector discoloration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a reflector is used to reflect light or heat from the heater onto heating target members, then heating efficiency of the heating target members is enhanced, but light or heat is reflected toward the heater causing decreased heating efficiency and potential discoloration of the reflector

Engineering Contradiction:
Improveheating efficiencyVSAvoidheat reflection toward heater
Core Design Contradiction:
Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The reflector is designed with a convex curved surface instead of a flat surface. This curvature causes light and heat from the heater to be reflected at divergent angles toward the heating target members (fixing belt and nip formation member), preventing concentrated reflection back toward the heater. The convex shape distributes the reflected energy across a wider area, reducing the amount of energy returning to the heater and preventing reflector discoloration while maintaining effective heating of the targets.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Use of energy by moving object

If a reflector with convex surface is used to redirect heat, then heating efficiency is improved, but the reflector may still store heat leading to discoloration over time

Engineering Contradiction:
Improveheating efficiencyVSAvoidreflector discoloration
Core Design Contradiction:
Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

A gap is introduced between the reflector and the heater, physically separating these two components. This gap prevents direct contact and reduces the path for heat to be absorbed by the reflector and subsequently stored. By extracting the reflector from immediate proximity to the heater, the design minimizes the reflector's exposure to intense radiant heat, thereby reducing heat storage and preventing discoloration while still allowing the convex surface to effectively redirect heat toward the heating targets.

Inventive Principle:
Principle #2Taking out (Extraction)

3Productivity

If the reflector is positioned close to the heater to maximize reflection, then heating efficiency increases, but the amount of heat reflected toward the heater increases causing energy loss

Engineering Contradiction:
Improveheating efficiencyVSAvoidheating time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The convex curved surface of the reflector is optimized to achieve effective heat redirection without requiring close proximity to the heater. The curvature geometry is designed to intercept radiant heat and redirect it toward the heating targets at optimal angles, maintaining high heating efficiency while allowing sufficient distance between the reflector and heater to minimize harmful reflections back to the heater.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The reflector is positioned and oriented in three-dimensional space to optimize its relationship with the heater and heating targets. By adjusting the spatial arrangement and angular orientation of the convex reflector surface, the design achieves effective heat redistribution toward the heating targets while minimizing the solid angle through which heat can reflect back to the heater, thereby reducing energy loss and heating time.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 improves heating efficiency, reduces heating time, and maintains high reflectance of reflectors even with prolonged use, ensuring consistent and energy-efficient operation.

Implementation Method 1

a reflector (26) inside the loop of the fixing belt to reflect light or heat from the heating member

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

a radiation heater such as a halogen heater or a carbon heater is used as a heating unit to heat the belt unit and the nip forming unit

Methodology Applied
Scientific EffectThermal Radiation: Thermal Radiation

Data Source

PatentEP3690554B1Fixing device and image forming apparatus including same
Publication Date: 2025.10.29 RICOH CO LTD
  • EP3690554B1 patent drawingFigure 1~2
  • EP3690554B1 patent drawingFigure 3
  • EP3690554B1 patent drawingFigure 4~6

AI summary

A fixing device (5) includes a fixing member (21), an opposed member (22), a nip formation member (24), a heating member (23), and a reflector (26). The fixing member (21) is in a cylindrical form. The opposed member (22) is opposed to an outer surface of the fixing member (21). The nip formation member (24) is inside a loop of the fixing member (21) to form a nip (N) with the opposed member (22) with the fixing member (21) interposed between the opposed member (22) and the nip formation member (24). The heating member (23) is inside the loop of the fixing member (21) to heat the fixing member and the nip formation member. The reflector (26) is inside the loop of the fixing member (21) to reflect light or heat from the heating member (23). The reflector (26) has a convex surface protruding toward the heating member (23).