Capacitive Touch Panel Signaling for EMI-Resistant Control

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Solution Overview

Problem

Capacitive touch panels are particularly susceptible to electromagnetic interference (EMI) from sources like radio frequency signals and power lines, which negatively impact their performance.

Innovation Solution

A touch control system utilizing a non-tapered continuous wave signal, generated by a non-tapered continuous wave generator, is employed to transmit signals through a capacitive touch panel, reducing EMI effects by minimizing bandwidth and enhancing immunity to electromagnetic interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional tapered wave signals are used for touch panel transmission, then the signal can be transmitted effectively, but the system is susceptible to electromagnetic interference (EMI) from radio frequency signals and power lines

Engineering Contradiction:
Improveimmunity to electromagnetic interferenceVSAvoidelectromagnetic interference susceptibility
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the signal parameters by using non-tapered continuous wave signals instead of conventional tapered wave signals. This parameter change reduces the bandwidth of the transmitted signal, thereby minimizing the frequency range over which electromagnetic interference can affect the touch panel system, improving immunity to EMI from radio frequency signals and power lines

Inventive Principle:
Principle #35Parameter changes

2Reliability

If broader bandwidth signals are used for touch panel transmission, then signal transmission coverage is improved, but spectral interference from electromagnetic sources increases

Engineering Contradiction:
Improvesignal transmission effectivenessVSAvoidspectral interference
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent modifies the signal bandwidth parameter by employing non-tapered continuous wave signals with reduced bandwidth compared to conventional signals. This parameter optimization maintains effective signal transmission for touch panel operation while minimizing spectral interference with radio frequency signals and other electromagnetic sources

Inventive Principle:
Principle #35Parameter changes

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 non-tapered continuous wave signal effectively mitigates electromagnetic interference, improving the reliability and performance of capacitive touch panels by reducing spectral interference and enhancing signal integrity.

Implementation Method 1

The non-tapered continuous wave generator generates a non-tapered continuous wave signal as a transmit signal for the transmitter

Methodology Applied
Scientific EffectElectromagnetic wave transmission: Electromagnetic Induction

Data Source

PatentEP4579405A1Touch control system
Publication Date: 2025.07.02 HIMAX TECH LTD
  • EP4579405A1 patent drawingFigure 1
  • EP4579405A1 patent drawingFigure 2A~2C
  • EP4579405A1 patent drawingFigure 3A

AI summary

A touch control system includes a touch panel composed of a plurality of transmit lines and a plurality of receive lines; a transmitter that transmits at least one transmit signal to corresponding transmit line; a receiver that receives at least one receive signal from corresponding receive line; and a non-tapered continuous wave generator that generates a non-tapered continuous wave signal as a transmit signal for the transmitter.