Induction Fuser with Nested Ferrite Cores for Rapid Warm-up
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Solution Overview
Problem
Existing fusers in image forming apparatuses, such as copying machines and printers, face challenges in efficiently heating fixing belts with small heat capacity, requiring quicker warm-up and energy savings.
Innovation Solution
A fuser design incorporating an induction-current generating coil (IH coil) with an external ferrite core and an internal ferrite core, where the first center angle of the internal ferrite core is larger than the second center angle of the external ferrite core, to efficiently induce and utilize magnetic flux for heat generation, reducing warm-up time and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a conventional induction heating coil is used to heat the fixing belt, then the fixing belt can be heated, but the warm-up time is long and energy consumption is high
Solution Approach 1:
The heating system is segmented into multiple independent heating zones along the fixing belt, with separate induction heating coils positioned at different locations. Each zone can be controlled independently, allowing parallel heating operations that reduce total warm-up time while optimizing energy distribution across the belt surface.
Solution Approach 2:
An internal ferrite core is nested inside the fixing belt, with external ferrite cores positioned outside the belt. This nested configuration creates multiple magnetic flux paths (through the belt and through the cores) that work simultaneously, significantly increasing heating efficiency and reducing both warm-up time and energy consumption.
2Use of energy by stationary object
If the heat generating layer of the fixing belt has small heat capacity, then energy can be saved, but the warm-up time increases
Solution Approach 1:
The system changes the magnetic properties of the ferrite cores by controlling their temperature, utilizing the Curie point phenomenon. Below the Curie temperature, the ferrite cores have high magnetic permeability and efficiently concentrate magnetic flux for heating. Above the Curie temperature, they lose magnetic properties, automatically preventing overheating. This parameter change enables efficient heating with low heat capacity materials while maintaining precise temperature control.
Solution Approach 2:
The nested configuration of internal and external ferrite cores creates multiple magnetic flux paths that simultaneously heat the thin heat generating layer, compensating for its low heat capacity and enabling rapid warm-up without requiring excessive energy input.
3Power
If ferrite cores are added to enhance magnetic flux utilization, then heating efficiency improves, but device complexity increases
Solution Approach 1:
The internal ferrite core is nested within the fixing belt structure, utilizing the belt's own geometry to accommodate the heating elements. This integration minimizes additional space requirements and reduces structural complexity compared to external heating systems.
Solution Approach 2:
The ferrite cores serve multiple functions: they concentrate magnetic flux for efficient heating, act as thermal mass to stabilize temperature, and provide automatic temperature control through the Curie point effect. This multi-functionality reduces the need for additional temperature control mechanisms, offsetting the added 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 design enhances heating efficiency, reduces warm-up time, and conserves energy by effectively using magnetic flux for heat generation in the fixing belt, ensuring quick and efficient image fixation.
Implementation Method 1
a heat generating section (60) including a conductive layer (60a) and configured to rotationally travel; an induction-current generating section (70) provided around an exterior of the heat generating section (60) and including an exciting coil (71) and ferrite cores (72, 76)
Implementation Method 2
an induction-current generating section (70) provided around an exterior of the heat generating section (60) and including an exciting coil (71) and ferrite cores (72, 76)
Implementation Method 3
an induction-current generating section (70) provided around an exterior of the heat generating section (60) and including an exciting coil (71) and ferrite cores (72, 76)
Data Source
AI summary
A fuser includes: a heat generating section including a heat generating layer and configured to rotationally travel; an induction-current generating section provided around the exterior of the heat generating section and including an exciting coil and an external ferrite core that covers the outer circumference of the exciting coil; an opposing section set in contact with the outer circumferential surface of the heat generating section; and an internal ferrite core arranged inside of the heat generating section in a position opposed to the exciting coil, a first center angle connecting both edges of the internal ferrite core and a rotation center of the heat generating section being larger than a second center angle connecting both edges of the external ferrite core and the rotation center of the heat generating section.