Inductor Core Surface Roughness for Electronic Pen Coil Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing electronic pens with ferrite core coils face high coil tension issues at the winding-starting side, leading to potential coil breakage or damage due to the surface roughness of the magnetic body core.
Innovation Solution
An inductor core with a magnetic main body having an inclined portion and a straight body portion, where the arithmetic mean roughness of the straight body portion is smaller than that of the inclined portion, reducing the likelihood of coil damage and providing a high anchor effect, thereby enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coil is wound around the magnetic body core with a conventional surface, then the coil comes into contact with the core and generates electromagnetic induction, but the coil tension becomes high at the winding-starting side and the coil may break or the cover portion may be damaged
Solution Approach 1:
The magnetic body core features a localized smooth portion with lower surface roughness (Ra ≤ 6.0 μm) at the winding-starting side, while other portions may have higher roughness. This local quality change reduces coil tension and prevents damage at the critical winding area without affecting the overall core structure or electromagnetic performance.
2Reliability
If the surface roughness of the magnetic body core is high, then the core provides sufficient anchor effect for the coil, but the coil is more likely to be damaged due to high tension at the winding-starting side
Solution Approach 1:
The core implements differentiated surface roughness: a smooth portion (Ra ≤ 6.0 μm) at the winding-starting side to protect the coil, and potentially rougher portions elsewhere to maintain anchor effect. This local differentiation resolves the conflict between coil protection and anchoring requirements.
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 inductor core design reduces the risk of coil breakage and damage, resulting in an electronic pen and input device with improved reliability and durability.
Implementation Method 1
a ferrite core having an outer periphery provided with an electromagnetic induction coil
Data Source
AI summary
An inductor core includes a magnetic main body having a pillar shape and comprised of a magnetic material. The magnetic main body includes an inclined portion including an inclined surface that constitutes an outer circumferential surface of a truncated cone having an outer diameter increasing from one end toward the other end; and a straight body portion that is coaxial with the inclined portion and includes an outer peripheral surface that constitutes an outer circumferential surface of a cylindrical column body extending from the other end toward the one end, the straight body portion being connected to the inclined portion. An arithmetic mean roughness Ra of an outer peripheral surface of the straight body portion located at or around the other end is smaller than an arithmetic mean roughness Ra of an outer peripheral surface of the straight body portion that is disposed at or around the inclined portion.