Conductive Pen Core Structure for Accurate Tilt Detection

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Solution Overview

Problem

Existing electronic pens with conductive core bodies experience waving phenomena in reception signals due to signal emission from the axis part, leading to poor linear characteristics and tilt detection issues, while softer materials for the nib compromise writing touch.

Innovation Solution

A cylindrical electronic pen design with a core body featuring a conductive core rod having a hemispherical front end, a tapered intermediate portion, and a back end, covered by a protective member, which maintains signal transmission and detects tilt accurately while ensuring soft writing touch.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the core body is formed as a columnar rod-shaped body entirely by conductive material, then the structure is simple and easy to manufacture, but the linear characteristics of detected position become poor when tilted due to unwanted signal emission from the axis part

Engineering Contradiction:

Improveease of manufactureVSAvoidlinear characteristics of detected position

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The core body is divided into two distinct parts: a conductive axis part and a non-conductive protective coating. This segmentation allows the axis part to provide structural support and controlled signal emission, while the coating prevents unwanted signal emission from the surface, thereby improving linear characteristics during tilted operation

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the core body are given different electrical properties: the axis part is conductive to provide structural support and controlled signal emission, while the protective coating is non-conductive to prevent unwanted signal emission. This local differentiation of material properties resolves the contradiction between manufacturing simplicity and measurement precision

Inventive Principle:

Principle #3Local quality

2Ease of operation

If softer material is used for the core body to improve writing touch, then the writing comfort increases, but the strength and durability of the core body decreases

Engineering Contradiction:

Improvewriting touchVSAvoidstrength of core body

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The core body uses a composite structure combining a conductive core material with a non-conductive protective coating. This composite design allows the core to provide the desired soft writing touch while the coating reinforces the overall structure, improving durability without compromising writing comfort

Inventive Principle:

Principle #40Composite materials

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 design allows for precise tilt detection and maintains linear characteristics of indicated positions, while providing a soft writing experience through the use of a conductive elastomer core rod protected by a non-conductive member.

Implementation Method 1

a core body including a core rod that is conductive, the core rod including a front portion that protrudes from the opening on the one end of the housing, a back portion, and an intermediate portion between the front portion and the back portion

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

the signal (electric field) from the signal generation circuit is transmitted from the nib as described above. Therefore, the core body of the electronic pen of the active electrostatic system of the related art is a columnar rod-shaped body, and the entire core body is formed by a conductive material

Methodology Applied

Scientific EffectElectric field emission: Electric Field

Implementation Method 3

a protection member that covers a side surface of the intermediate portion of the core rod

Methodology Applied

Scientific EffectMechanical protection:

Data Source

PatentUS12625570B2Electronic pen and core body for electronic pen including conductive core rod and protection member that covers core rod

Publication Date: 2026.05.12 WACOM CO LTD

AI summary

An electronic pen includes a cylindrical housing including an opening on one end of the housing in an axial direction of the housing, a core body attached inside of the housing such that an end of the core body protrudes from the opening on the one end of the housing, and a signal generation circuit which, in operation, generates a signal that is transmitted from the core body. The core body includes a core rod that is conductive and a protection member. The core rod includes a front portion that protrudes from the opening on the one end of the housing, a back portion, and an intermediate portion between the front portion and the back portion. The intermediate portion has a tapered shape narrowing from the front portion toward the back portion. The core rod receives the signal from the signal generation circuit. The protection member covers a side surface of the intermediate portion of the core rod.