Induction Heating Roller for Image Forming Apparatus
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Solution Overview
Problem
Existing image forming apparatuses face challenges with induction heating fusing devices, including slow heat transfer in internal coil types and reduced heating performance at ends in external coil types, which necessitate larger apparatus sizes and increased temperatures on unused areas of heating rollers during small-size paper printing.
Innovation Solution
An apparatus with a first induction coil outside the heating roller and second induction coils at its ends, controlled by a power supply unit and control unit to adjust current flow direction based on paper size, ensuring efficient heat distribution without increasing the roller size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heating roller is lengthened to increase heating performance at both ends, then the heating performance is improved, but the size of the image forming apparatus increases
Solution Approach 1:
The patent applies local quality by providing different heating configurations for different regions of the heating roller. Specifically, the first induction coil is positioned to heat the central region while the second induction coils are positioned to heat both ends, creating localized heating zones with different characteristics. This allows optimized heating performance at each location without requiring a uniformly longer heating roller, thus avoiding increase in the overall size of the image forming apparatus.
2Ease of manufacture
If the external coil type fusing device is used to avoid replacement cost, then the cost is reduced, but the heating performance at both ends is drastically reduced
Solution Approach 1:
The patent applies segmentation by dividing the induction heating system into multiple independent coils: a first induction coil for the central region and second induction coils for both ends. This segmented approach allows each coil to be independently controlled and optimized for its specific region, ensuring high heating performance at both ends while maintaining the external coil type configuration that avoids expensive ferrite core and induction coil replacement issues.
3Productivity
If paper having small size is printed, then the productivity is improved, but the temperature of unused area of heating roller increases
Solution Approach 1:
The patent applies periodic action through the control unit that periodically adjusts the operation of induction coils based on paper size detection. When small size paper is detected, the control unit controls the first and second induction coils to operate in a periodic manner, turning them on and off in coordination with paper feeding, which prevents unnecessary heating of unused areas while maintaining high printing speed for small size papers.
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
Enables high-efficiency printing without enlarging the heating roller and prevents temperature increases on unused areas, maintaining high heat emission efficiency at both ends.
Implementation Method 1
a first induction coil that is disposed outside the heating roller and heats the heating roller by using induced current generated according to current flowing through the first induction coil
Implementation Method 2
two second induction coils that are disposed at upper portions of both ends of the first induction coil and heat the heating roller by using induced current generated according to current flowing through the two second induction coils
Data Source
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AI summary
The apparatus includes a heating roller (110) that generates heat for melting toner attached to a printing medium; a first induction coil (120) that is disposed outside the heating roller and heats the heating roller by using induced current generated according to current flowing through the first induction coil; two second induction coils (130,131) that are disposed at upper portions of both ends of the first induction coil and heat the heating roller by using induced current generated according to current flowing through the two second induction coils; a power supply unit (140) that supplies current to the first induction coil and the two second induction coils; and a control unit (150) that controls the power supply unit to supply current flowing in the same direction or different directions to the first induction coil and the second induction coils according to the size of paper fed into the heating roller.