Fuser Heater Terminal Layout for Non-Sheet Overheating Control

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Solution Overview

Problem

Existing fixing devices with cylindrical films face overheating issues in non-sheet-passing portions due to reduced heat capacity, leading to component damage, and the arrangement of power supply terminals and cables is challenging in small heat generating blocks.

Innovation Solution

The fixing device efficiently arranges power supply terminals and cables within the internal space of the film by using a configuration that allows independent power supply to each heat generating block, minimizing interference and enabling precise temperature control through thermistors, while reducing the device's size by optimizing cable routing and component placement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the heat generating block size is reduced to match small recording material sizes, then heat generation distribution corresponds to the size of recording material, but the area for arranging power supply terminals and cables becomes insufficient

Engineering Contradiction:
Improveheat generation distributionVSAvoidarea for power supply terminal arrangement
Core Design Contradiction:
TemperatureVSArea of stationary object

Solution Approach 1:

The patent extends the arrangement of power supply terminals from the limited planar area of the heat generating block to the cylindrical surface of the film. By utilizing the circumferential direction of the film, the available arrangement area is significantly increased, allowing multiple power supply terminals to be distributed along the film's circumference rather than being constrained to a small rectangular area.

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

Solution Approach 2:

The power supply terminals are arranged within the internal space of the cylindrical film structure. The film itself serves as both the heating element and the containment structure for the power supply terminals, effectively nesting the electrical components within the film's hollow interior space.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If power supply terminals are densely arranged in small areas, then electrical short circuits between adjacent terminals are prevented, but the arrangement of power supply cables becomes more difficult

Engineering Contradiction:
Improveprevention of electrical short circuitVSAvoidarrangement of power supply cable
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

By arranging power supply terminals along the circumferential direction of the cylindrical film, the patent transforms a two-dimensional dense packing problem into a three-dimensional distributed arrangement. This spatial redistribution provides adequate clearance between terminals while maintaining compact overall dimensions, and creates natural pathways for cable routing along the film's exterior surface.

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

Solution Approach 2:

The cylindrical film structure serves as a flexible mounting surface for power supply terminals. The curved surface of the film allows terminals to be positioned at optimal intervals while maintaining structural integrity, and the film's exterior provides a convenient pathway for cable routing that avoids interference with adjacent components.

Inventive Principle:
Principle #30Flexible shells and thin films

3Adaptability or versatility

If non-sheet-passing portions of the fixing device are present, then small-size sheets can be printed, but these portions overheat due to reduced heat transfer

Engineering Contradiction:
Improvecapability to print small-size sheetsVSAvoidtemperature of non-sheet-passing portion
Core Design Contradiction:
Adaptability or versatilityVSTemperature

Solution Approach 1:

The patent applies different heating characteristics to different regions of the fixing device. By controlling the power supply to heat generating blocks corresponding to non-sheet-passing portions, the system can provide localized heating where needed while reducing or eliminating heat generation in areas where sheets do not pass, preventing overheating of specific regions.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The heating system operates in a periodic or controlled manner, activating heat generating blocks only when sheets are present in corresponding regions. This allows the system to adapt heating patterns dynamically, providing heat when needed for sheet processing while avoiding continuous heating that would cause overheating in non-sheet-passing areas.

Inventive Principle:
Principle #19Periodic action

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 in non-sheet-passing areas and ensures reliable power supply to each block, enhancing the device's durability and efficiency by maintaining optimal temperature distribution and reducing the risk of electrical short circuits.

Implementation Method 1

a heat generating element on a heater substrate is divided into a plurality of heat generating blocks

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a power supply unit with elastic contact portions

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4290312B1Fixing device
Publication Date: 2026.04.29 CANON KK
  • EP4290312B1 patent drawingFigure 1
  • EP4290312B1 patent drawingFigure 2
  • EP4290312B1 patent drawingFigure 3

AI summary

In a fixing device, a connection portion of a first power supply terminal is at a position closer to one end portion of a heater in a longitudinal direction of the heater than a contact portion of the first power supply terminal, and a connection portion of a second power supply terminal is at a position closer to the other end portion of the heater in the longitudinal direction than a contact portion of the second power supply terminal. A power supply cable connected to the connection portion of the first power supply terminal extends toward the one end portion of the heater, and a power supply cable connected to the connection portion of the second power supply terminal is bent from extending toward the other end portion of the heater to extend toward the one end portion of the heater.