Induction Heating Fixing Unit With Insulated Shaft
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Solution Overview
Problem
In induction-heating type fixing apparatuses, variations in the distance between the magnetic body and the object to be heated lead to irregular temperature distribution, affecting the quality of the toner image fixed on a sheet, and there is a need for electrical insulation between the metal shaft and the coil to prevent current leakage.
Innovation Solution
A fixing unit with a looped coil surface, an upright wall, a center core with a conductive shaft and magnetic tube, and a nonconductive cap inserted into the opening to electrically insulate the coil from the conductive shaft, ensuring consistent induction-heating and preventing electrical interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the magnetic tube is positioned closer to the coil for efficient induction-heating, then heating efficiency is improved, but electrical insulation between the metal shaft and coil becomes problematic
Solution Approach 1:
A non-conductive cap is introduced as an intermediary component between the metal shaft and the coil. This cap covers the shaft surface at the position facing the coil, preventing direct electrical contact while allowing the magnetic tube to remain close to the coil for efficient induction-heating. The intermediary element resolves the contradiction by enabling both close positioning for heating efficiency and electrical insulation for reliability.
Solution Approach 2:
The shaft is segmented functionally by adding the non-conductive cap as a separate component. The shaft itself remains conductive for structural integrity, while the cap provides localized electrical insulation only where needed (at the coil-facing surface). This segmentation allows the system to maintain both electrical insulation where required and conductivity where needed for the induction-heating function.
2Stability of the object's composition
If the shaft is made of metal to reduce twisting, then structural stability is improved, but electrical leakage to the coil occurs
Solution Approach 1:
The non-conductive cap acts as an intermediary that blocks the harmful electrical leakage path from the metal shaft to the coil. The shaft retains its full metal construction for structural stability, while the cap provides a non-conductive barrier that eliminates the harmful electrical leakage effect without compromising the shaft's mechanical properties.
Solution Approach 2:
The potential harmful effect of the metal shaft's conductivity is converted into a benefit by using the non-conductive cap to create a controlled insulation interface. The shaft's metal nature provides structural stability, and the cap transforms the potential electrical leakage hazard into a designed insulation feature that protects the coil while maintaining shaft integrity.
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
The solution provides consistent and efficient induction-heating, ensuring uniform temperature distribution and preventing electrical interference, thereby improving the quality of the toner image fixation on the sheet.
Implementation Method 1
a looped coil surface formed with a coil so that the coil surface generates a magnetic field for induction-heating the first element
Implementation Method 2
Heating by electromagnetic induction is more rapid and efficient heating manner. Therefore, heating by electromagnetic induction (hereinafter called "induction-heating" or "IH") is used for various apparatuses.
Data Source
AI summary
A fixing unit for fixing a toner image onto a sheet passing between a first element and a second element pressed against the first element includes a looped coil surface formed with a coil so that the coil surface generates a magnetic field for induction-heating the first element, the coil surface including an inner edge defining an opening region; an upright wall disposed inside the opening region, an opening being formed in the upright wall; a center core disposed along the opening region, the center core including a conductive shaft and a magnetic tube configured to at least partially cover the conductive shaft; and a nonconductive cap inserted into the opening, the nonconductive cap partially covering the conductive shaft to electrically insulate the coil from the conductive shaft.