Fuser Heater Layout for Uniform Toner Fixing Temperature

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Solution Overview

Problem

Existing image forming apparatuses face challenges in effectively controlling the heating temperature of heating units to fix toner images on sheets, leading to inefficiencies and potential damage due to uneven temperature distribution and lack of precise control.

Innovation Solution

The heating unit incorporates a locking portion, insulating film, and a metal plate with a locking portion to restrict movement, along with independent control of multiple heating elements and temperature sensors to ensure uniform heat distribution and precise temperature regulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If heating elements are positioned closer to the film to improve heating efficiency, then heating speed increases, but temperature distribution becomes uneven causing localized overheating

Engineering Contradiction:
Improveheating speedVSAvoidtemperature distribution uniformity
Core Design Contradiction:
SpeedVSTemperature

Solution Approach 1:

The patent divides the heating system into multiple independent heating elements (first, second, third, and fourth heating elements) positioned at different locations. Each heating element can be controlled independently to provide localized heating, allowing the system to maintain uniform temperature distribution across the film while preventing localized overheating. This resolves the contradiction by making heating quality spatially variable rather than uniform.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The heating system is segmented into multiple separate heating elements rather than using a single heating source. This segmentation allows independent control of each heating element, enabling precise temperature management at different locations on the film. The segmented approach maintains heating speed while ensuring uniform temperature distribution through coordinated control of individual segments.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If heating temperature is increased to improve fixation quality, then image fixation quality improves, but risk of overheating and damage increases

Engineering Contradiction:
Improveimage fixation qualityVSAvoidoverheating damage
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent incorporates temperature sensors (first and second temperature sensors) that continuously monitor the temperature at different locations on the film. This feedback information is used to dynamically adjust the heating elements, ensuring the temperature remains within the optimal range for image fixation while preventing overheating damage. The feedback mechanism resolves the contradiction by enabling precise temperature control that maintains fixation quality without exceeding safe temperature limits.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The heating system transitions from static, uniform heating to dynamic, location-specific heating control. Each heating element can be independently adjusted based on real-time temperature feedback, allowing the system to adapt heating intensity to the specific needs of different film regions. This dynamic control ensures optimal fixation quality while preventing overheating damage through continuous adjustment.

Inventive Principle:
Principle #15Dynamics

3Temperature

If heating elements are distributed across the film to improve temperature uniformity, then temperature distribution improves, but device complexity increases

Engineering Contradiction:
Improvetemperature distribution uniformityVSAvoidheating system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent uses a common insulating substrate that serves multiple functions: it provides electrical insulation for all heating elements, provides a mounting surface for temperature sensors, and serves as the base structure for the entire heating assembly. This multi-functionality reduces device complexity despite the presence of multiple heating elements and sensors, as a single component performs several critical roles in the system.

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

4Measurement precision

If multiple temperature sensors are added to improve temperature control precision, then temperature regulation accuracy improves, but device complexity increases

Engineering Contradiction:
Improvetemperature control accuracyVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The insulating substrate serves as a common mounting platform for both heating elements and temperature sensors, eliminating the need for separate sensor mounting structures. This multi-functional use of the substrate reduces overall device complexity while allowing multiple temperature sensors to be integrated into the system for improved temperature control accuracy.

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 allows for efficient and uniform heating of sheets, preventing overheating and enhancing the durability of the heating unit while ensuring consistent image fixation quality.

Implementation Method 1

a first heating element on the first surface of the substrate at a first position along the axial direction, a second heating element on the first surface of the substrate at a second position along the axial direction

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

an insulating film between the first surface of the substrate and the first and second heating elements

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP3819712B1Heating unit and image processing apparatus
Publication Date: 2025.12.31 TOSHIBA TEC KK
  • EP3819712B1 patent drawingFigure 1
  • EP3819712B1 patent drawingFigure 2
  • EP3819712B1 patent drawingFigure 3

AI summary

A heating unit includes a cylinder which rotates about an axis parallel to a first direction. A heater has a first surface abutting on an inner surface of the cylinder at a nip position. A support member is on a second surface of the heater and also contacts the cylinder. A first heating element is in the heater at a first position along the first direction. A second heating element in the heater is at a second position spaced from the first position. A first temperature sensor is above the first position. A locking portion of the heater is at a third position along the first direction. The locking portion engages the support member and restricts movement of the heater in the first direction. The first position is near a first outer edge of the cylinder. The second position is closer to a central portion of the cylinder.