Ferrite Core Geometry for Stronger Stylus Pen Signals

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Solution Overview

Problem

Existing stylus pens face challenges in maximizing the magnitude of pen signals received by receivers due to limitations in ferrite core design, which affects signal transmission and recognition precision, especially when inclined at angles, and require additional components like EMR sensors, increasing cost and thickness.

Innovation Solution

A ferrite core with a specific shape and configuration, featuring a through-hole and curved portions, allows for improved signal reception by positioning the inductor unit closer to the receiver, reducing buffer thickness, and enabling stable accommodation within the housing while maintaining operational stability and precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a typical ferrite core design is used, then the stylus pen structure is simple, but the signal magnitude received by the receiver is insufficient

Engineering Contradiction:

Improvesignal magnitudeVSAvoidferrite core structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The ferrite core transitions from a conventional cylindrical shape to a multi-dimensional complex geometry featuring a through-hole along the longitudinal axis, curved portions at both ends, and asymmetric cross-sections. This dimensional complexity enables the inductor unit to be positioned closer to the receiver while maintaining structural stability, thereby enhancing signal magnitude without compromising device simplicity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Different portions of the ferrite core are designed with distinct geometric characteristics: the through-hole provides magnetic flux pathways, the curved portions enable compact positioning, and the asymmetric cross-sections optimize magnetic field distribution. Each local feature contributes specifically to improving signal transmission efficiency

Inventive Principle:

Principle #3Local quality

2Reliability

If the inductor unit is positioned closer to the receiver, then signal reception is improved, but the stylus pen thickness increases

Engineering Contradiction:

Improvesignal receptionVSAvoidstylus pen thickness

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The ferrite core's through-hole configuration allows the inductor unit to be nested within or adjacent to the core structure in a space-efficient manner. This nesting arrangement enables the inductor to be positioned closer to the receiver without increasing the overall stylus pen thickness, as the components share the same spatial envelope

Inventive Principle:

Principle #7Nested doll (Nesting)

3Reliability

If a complex ferrite core shape is used, then signal transmission is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvesignal transmissionVSAvoidferrite core fabrication

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The ferrite core is designed with pre-formed through-holes and curved portions that are integrated into the core fabrication process itself. By incorporating these features during the initial sintering or molding stage rather than adding them through secondary operations, the manufacturing complexity is minimized while achieving the desired complex geometry for optimal signal transmission

Inventive Principle:

Principle #10Preliminary action

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 optimized ferrite core enhances signal magnitude and recognition accuracy, allowing precise touch detection and reduced stylus pen thickness, addressing the limitations of existing designs and reducing manufacturing complexity.

Implementation Method 1

the capacitive resonance method uses a general capacitance touch sensor and a general touch controller IC to increase a performance of the IC and support a pen touch

Methodology Applied

Scientific EffectElectromagnetic resonance: Resonance

Implementation Method 2

the EMR method that is an inductive resonance method

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS12554341B2Ferrite core and stylus pen including the same

Publication Date: 2026.02.17 HIDEEP INC

AI summary

A stylus pen may be optimized to a housing having a specific shape and may improve a magnitude of a pen signal. A ferrite core is mounted in a stylus pen and has a through-hole formed along a longitudinal direction of the stylus pen. The ferrite core has a first cross-sectional shape in a first vertical direction perpendicular to the longitudinal direction and a second cross-sectional shape in a second vertical direction perpendicular to both the longitudinal direction and the first vertical direction, the first cross-sectional shape is different from the second cross-sectional shape, the ferrite core includes a curved portion disposed at one end of the ferrite core, and the curved portion includes at least two curved surfaces that are curved from one side surface of one end of the ferrite core to a portion adjacent to the through-hole of the ferrite core in a direction toward the through-hole.