Induction Heating Fixing Apparatus with Localized Coil Winding
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Solution Overview
Problem
Existing fixing apparatuses with electromagnetic induction heating systems face challenges in temperature control, particularly during the fixation of toner images on small recording media, leading to temperature rises in non-sheet-passing portions.
Innovation Solution
A fixing apparatus with a tubular rotation member and a helical coil that uses a resonance circuit and inverter to control electromagnetic induction heating, where the driving frequency of the inverter is adjusted based on the size and temperature of the recording medium to optimize heat generation distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If electromagnetic induction heating is used to fix toner images on small recording media, then warm-up time is reduced, but temperature rises occur in non-sheet-passing portions
Solution Approach 1:
The patent applies local quality by varying the coil winding density along the axial direction of the heating member. The coil has a first winding density in a first axial region and a second winding density in a second axial region, where the winding densities differ. This creates non-uniform magnetic flux distribution that generates heat preferentially in the sheet-passing portion while suppressing heat generation in the non-sheet-passing portion, thus resolving the temperature rise problem while maintaining fast warm-up capability.
2Ease of manufacture
If uniform coil winding is used throughout the heating member, then manufacturing is simple, but heat generation is uniform causing temperature rise in non-sheet-passing portions
Solution Approach 1:
The coil is designed with different winding densities in different axial regions. The first coil winding density differs from the second coil winding density, creating localized variations in magnetic flux density. This results in non-uniform heat generation that concentrates in the sheet-passing portion, preventing temperature rise in non-sheet-passing portions while remaining manufacturable.
Solution Approach 2:
The patent changes the coil winding density parameter along the axial direction. By adjusting the winding density from the first region to the second region, the magnetic flux density and consequently the heat generation rate are varied. This parameter change enables precise control over heat distribution to suppress unwanted temperature rise in non-sheet-passing portions.
3Productivity
If high power is supplied to generate sufficient heat for fixing, then fixing speed increases, but temperature rise in non-sheet-passing portions worsens
Solution Approach 1:
The differentiated coil winding density creates local variations in heat generation. The sheet-passing portion receives higher magnetic flux density and thus higher heat generation rate for fast fixing, while the non-sheet-passing portion receives lower heat generation to prevent temperature rise. This local quality approach enables high productivity without compromising temperature control.
Solution Approach 2:
The patent employs resonance frequency control in the electromagnetic induction heating system. By operating at or near the resonance frequency of the heating member, the system achieves efficient heat generation with lower power requirements. This periodic action at optimized frequency allows sufficient heat generation for fast fixing while minimizing overall power consumption and preventing excessive temperature rise in non-sheet-passing portions.
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 suppresses temperature rises in non-sheet-passing portions and ensures sufficient power supply for fixing, enhancing the efficiency and reliability of the fixing process.
Implementation Method 1
the conductive layer generates heat with electromagnetic induction caused by magnetic flux generated through the coil
Implementation Method 2
a resonance circuit, including a resonance capacitor, formed with the rotation member and the coil
Data Source
AI summary
A fixing apparatus includes a tubular rotation member including a conductive layer, a helical coil, a resonance circuit, including a resonance capacitor, formed with the rotation member and the coil, a resonance inverter configured to control the resonance circuit, and a control unit configured to control electric power supplied to the resonance inverter, wherein the conductive layer generates heat with electromagnetic induction caused by magnetic flux generated through the coil, wherein the control unit sets a driving frequency of the resonance inverter according to at least one of a size of the recording medium and a temperature of a non-sheet-passing portion of the rotation member, and wherein the control unit changes a resonance frequency of the resonance circuit according to the set driving frequency.