Movable Magnetic Core for Induction Heating Flux Control
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Solution Overview
Problem
Image heating apparatuses face challenges with 'out-of-path temperature increase' due to uneven heat distribution on the fixation roller, leading to excessive temperature in non-recording-medium-path portions, which can cause the magnetic core to exceed its Curie temperature and reduce magnetic flux efficiency.
Innovation Solution
The apparatus adjusts the distance between the external coil and magnetic core using a movable magnetic core and electroconductive members to form a magnetic circuit, reducing magnetic flux leakage and heat generation in non-path areas, while maintaining efficiency for recording medium heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the magnetic core is positioned close to the exciter coil for efficient induction heating, then the thermal efficiency for heating the recording medium path is improved, but the out-of-path temperature increase occurs causing excessive heat in non-recording-medium-path portions
Solution Approach 1:
The magnetic core is divided into multiple sections along the circumferential direction, with each section independently controllable. This allows selective positioning of magnetic core sections to match different recording medium sizes, reducing out-of-path heat generation while maintaining heating efficiency for the recording medium path.
Solution Approach 2:
The magnetic core sections are made movable relative to the exciter coil, enabling dynamic adjustment of the magnetic core position according to recording medium size. This dynamic reconfiguration optimizes the magnetic circuit for different conditions, preventing excessive heat in non-path areas while maintaining efficient heating when needed.
2Temperature
If the distance between the exciter coil and magnetic core is increased to reduce out-of-path temperature increase, then the excessive heat in non-recording-medium-path portions is reduced, but the thermal efficiency for heating the recording medium path decreases
Solution Approach 1:
By segmenting the magnetic core into multiple independently controllable sections, the system can position only the necessary sections close to the exciter coil for efficient heating, while keeping other sections at a distance to reduce out-of-path heat generation.
Solution Approach 2:
Different sections of the magnetic core can be positioned at different distances from the exciter coil based on local requirements. Sections corresponding to the recording medium path are positioned close for efficient heating, while sections in non-path areas are positioned farther away to reduce excessive heat generation.
3Device complexity
If a fixed magnetic core structure is used, then the device complexity is reduced, but the adaptability to different recording medium sizes is limited
Solution Approach 1:
The magnetic core is segmented into multiple sections that can be independently positioned, allowing the system to adapt to different recording medium sizes without requiring a completely different magnetic core structure for each size.
Solution Approach 2:
The magnetic core sections are made dynamically adjustable, enabling the system to reconfigure the magnetic circuit according to different recording medium sizes, thereby achieving versatility without excessive structural complexity.
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 solution effectively reduces heat generation in non-path areas of the fixation roller, preventing excessive temperature increases and maintaining thermal efficiency for image heating, even with varying recording media sizes.
Implementation Method 1
the heat generated by generating an eddy current in the inductive heating portion of the fixation roller, by the magnetic field generated by an exciter coil
Implementation Method 2
the method which heats the fixation roller by Joule heat, that is, the heat generated by generating an eddy current
Implementation Method 3
a movable magnetic core provided at a position opposed to the coil
Implementation Method 4
an electroconductive member mounted at a position where a magnetic circuit is capable of being formed with the coil
Data Source
AI summary
An image heating apparatus includes an endless rotatable heat generator for heating an image on the recording material by induction heat generation by a magnetic flux, a coil outside the generator for generating the magnetic flux for the induction heat generation, first and second magnetic cores, respectively provided on the same and opposite sides of the coil as the heat generator for directing the magnetic flux to the heat generator, a mover for moving the second core between first and second positions, the second position being farther away from the coil than the first position, and an electroconductive member extending from the first core to the second position in a direction away from the heat generator.