Capacitive Button Electrode Layout for ESD Tolerance

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Solution Overview

Problem

The configuration of existing proximity sensors, when applied to capacitive buttons, results in insufficient tolerance to electrostatic discharge due to electrostatic discharge reaching the sensor electrode.

Innovation Solution

A capacitive button design featuring a pair of sensor electrodes arranged side by side with a floating electrode and a ground electrode surrounding the floating electrode, which is grounded without electrical connection to the sensor electrodes, improving tolerance to electrostatic discharge by capacitive coupling with the floating electrode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a proximity sensor configuration is applied to a capacitive button, then miniaturization is achieved, but tolerance to electrostatic discharge becomes insufficient

Engineering Contradiction:

Improvesize of capacitive buttonVSAvoidtolerance to electrostatic discharge

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

A ground electrode is introduced as an intermediary component between the sensor electrode and the external environment. This ground electrode serves as a mediator that intercepts electrostatic discharge before it can reach the sensor electrode, thereby protecting the sensitive sensing elements while maintaining the compact proximity sensor configuration

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful electrostatic discharge into a beneficial protective mechanism. By providing a ground electrode that attracts and dissipates electrostatic charge, the harmful ESD energy is redirected away from the sensor electrode, transforming what would be a destructive force into a protective feature that enhances reliability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

Enhances the capacitive button's tolerance to electrostatic discharge and stabilizes detection performance by directing discharge current away from the sensor electrodes to the ground electrode, thereby improving functionality and reliability.

Implementation Method 1

improving tolerance to electrostatic discharge by capacitive coupling with the floating electrode

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 2

electrostatic discharge reaches a sensor electrode

Methodology Applied

Scientific EffectElectrostatic discharge: Electrostatic Discharge

Data Source

PatentUS20240072798A1Capacitive button

Publication Date: 2024.02.29 MITSUBISHI ELECTRIC CORP

AI summary

A capacitive button capable of improving tolerance to electrostatic discharge is provided. The capacitive button includes: a pair of sensor electrodes which are provided side by side; a floating electrode which is arranged on a front side of the pair of sensor electrodes via an insulating layer; and a ground electrode which is arranged so as to surround the floating electrode, and is grounded without being electrically connected with the pair of sensor electrodes and the floating electrode. By providing the configuration, the tolerance to the electrostatic discharge of the capacitive button can be improved.