Electronic Pen Core Rod Strength Design

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Solution Overview

Problem

Conventional electronic pens used with position detection apparatuses are thicker due to incorporated circuit boards, making them prone to bending or breaking when slimmed down, especially at the pen tip where writing pressure is applied.

Innovation Solution

An electronic pen design featuring a housing with a core unit comprising a columnar magnetic core with a wound coil and a core rod extending from one end, and a first coil non-winding portion at the pen tip, which enhances the pen's strength by distributing stress and preventing bending or breaking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If the electronic pen is slimmed down by reducing the thickness of the outer side housing and circuit board components, then the overall thickness of the electronic pen is reduced, but the strength of the electronic pen becomes weak making it liable to be bent or broken

Engineering Contradiction:
Improvethickness of electronic penVSAvoidstrength of electronic pen
Core Design Contradiction:
Length of stationary objectVSStrength

Solution Approach 1:

The patent applies composite material principles by combining the magnetic core (ferrite or similar magnetic material) with the coil structure to form a core unit that provides both electromagnetic functionality and structural strength. This composite structure allows the pen to be slimmed down while maintaining strength through the inherent rigidity of the magnetic core material

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent segments the electronic pen into distinct functional units: the core unit (magnetic core + coil), the circuit board unit, and the housing. This segmentation allows the core unit to serve as a structural backbone that maintains pen strength while other components are minimized for thinness

Inventive Principle:
Principle #1Segmentation

2Reliability

If the coil is wound over the entire magnetic core, then the electromagnetic induction coupling function is maximized, but the pen tip side lacks structural reinforcement making it more susceptible to bending or breaking under writing pressure

Engineering Contradiction:
Improveelectromagnetic coupling functionVSAvoidstrength at pen tip
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The coil winding is segmented into two distinct regions: a coil winding portion that provides electromagnetic functionality and a coil non-winding portion that provides structural reinforcement at the pen tip. This segmentation allows the pen tip to have enhanced strength without compromising the overall electromagnetic coupling function

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by providing different structural characteristics at different locations of the magnetic core. The coil winding portion has optimized electromagnetic properties while the coil non-winding portion has optimized mechanical strength properties, allowing each region to perform its specific function effectively

Inventive Principle:
Principle #3Local quality

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 electronic pen maintains strength even when slimmed down, preventing bending or breaking at the pen tip under external pressure, ensuring durability and functionality.

Implementation Method 1

an electronic pen of an electromagnetic induction coupling type is disclosed in US-A1-2016/018912

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a core unit configured from a columnar magnetic core on which a coil is wound and a core rod fixed from one end to the other end of a position including a center line of the magnetic core

Methodology Applied
Scientific EffectStructural reinforcement through core rod:

Data Source

PatentEP3447615B1Electronic pen and electronic pen body
Publication Date: 2020.11.25 WACOM CO LTD
  • EP3447615B1 patent drawingFigure 1A~1B
  • EP3447615B1 patent drawingFigure 2A~2C
  • EP3447615B1 patent drawingFigure 3A~3B

AI summary

Provided is an electronic pen whose strength is increased such that especially a pen tip portion to which external force is likely to apply is not bent or broken even if the electronic pen is slimmed down. A core unit (30) is configured from a ferrite core (32) on which a coil (31) is wound and a core rod (34). The core rod (34) is fixed from one end to the other end of a position including the center line of the ferrite core (32) and projects at an end portion (34a) thereof from the one end of the ferrite core (32). A first coil non-winding portion (32b) on which the coil (31) is not wound is provided on the pen tip side of the ferrite core (32). Where the electronic pen is used as an electronic pen, it indicates a state in which the end portion (34a) of the core rod (34) projecting from the one end of the ferrite core (32) and part of the first coil non-winding portion (32b) of the ferrite core (32) project from an opening (2b) of a housing (2).