Elliptical Magnetic Core for Thin Position Indicator Signal Integrity
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Solution Overview
Problem
The existing electromagnetic induction type position indicators with cylindrical magnetic cores face challenges in miniaturization due to the reduction in cross-sectional area, leading to decreased signal reception and increased susceptibility to damage from impacts when housed in thin portable terminals.
Innovation Solution
A position indicator with a columnar magnetic core having a flat cross-sectional shape and tapered portions, allowing for a thinner design while maintaining signal integrity and enhancing durability by concentrating magnetic flux and distributing stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cylindrical magnetic core with a perfectly round cross section is used, then the position indicator can be manufactured with ease and coil winding is simplified, but the cross-sectional area is reduced when miniaturized, leading to decreased signal reception capability
Solution Approach 1:
The patent applies asymmetry by changing the magnetic core from a perfectly round cylindrical cross-section to an elliptical cross-section. This asymmetric shape increases the cross-sectional area compared to a circular core of the same major axis length, thereby improving signal reception capability while maintaining manufacturability. The elliptical shape allows for better magnetic flux distribution and enhanced coupling with the coil.
Solution Approach 2:
The patent utilizes dimensionality change by transitioning from a circular cross-section (one degree of freedom in radius) to an elliptical cross-section (two degrees of freedom in major and minor axes). This allows optimization of the cross-sectional area by adjusting both axes independently, enabling better signal reception while controlling the overall size for miniaturization applications.
2Length of moving object
If the magnetic core is made thinner to reduce the thickness of portable terminals, then the terminal casing can be thinned, but the magnetic core becomes more susceptible to damage from impacts
Solution Approach 1:
The patent applies composite materials by combining the magnetic core material with a shock-absorbing material to form a composite structure. This composite construction allows the magnetic core to be made thinner for terminal miniaturization while the shock-absorbing material provides enhanced resistance to impact damage, resolving the contradiction between thinness and strength.
Solution Approach 2:
The patent implements beforehand cushioning by incorporating a shock-absorbing material that provides protective cushioning to the magnetic core before impact occurs. This pre-positioned cushioning layer absorbs impact energy and protects the thin magnetic core from damage, enabling the position indicator to be made thinner without compromising durability.
3Ease of operation
If a through hole is provided in the magnetic core for inserting the core body, then the core body can be properly positioned, but the magnetic core material thickness is reduced, increasing susceptibility to impact damage
Solution Approach 1:
The patent applies local quality by providing the through hole only in the minor axis direction of the elliptical magnetic core, rather than in all directions. This selective positioning maintains sufficient magnetic core material thickness in the major axis direction, preserving impact resistance while still enabling proper core body insertion and positioning in the necessary direction.
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 enables effective signal transmission and reception while providing improved pen pressure detection and resistance to impact damage, allowing for the thinning of portable terminal casings without degrading performance.
Implementation Method 1
The electromagnetic induction type position indicator has a resonance circuit formed by connecting a capacitor for resonance to a coil wound around a ferrite core
Implementation Method 2
The core body is formed by a rod-shaped member having a substantially uniform thickness (diameter). The core body is made of an elastic material so as not to damage an input surface formed by a glass surface or the like
Data Source
Figure 1(A)~1(B)
Figure 2
Figure 3(A)~3(F)
AI summary
An object of the present invention is to realize thinning of a casing of a position indicator while preventing degradation in signals transmitted and received to and from a sensor of a position detecting device. The position indicator includes a columnar magnetic core provided within a cylindrical casing with an axial direction of the casing as a direction of a central axis of the magnetic core. A coil is wound so as to have the central axis of the columnar magnetic core as a center. A core body is provided so as to have a tip portion exposed to an outside from an opening formed on one end side in the axial direction of the cylindrical casing. The magnetic core has a flat cross-sectional shape, and has a tapered portion formed on a side of the tip portion of the core body in the direction of the central axis of the magnetic core, the tapered portion being tapered off toward the tip portion of the core body.