Touch Panel Differential Electrodes for False Touch Suppression

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Solution Overview

Problem

Touch panels using electrostatic capacitance type sensors face erroneous detection due to external noise, where the user's body acts as an antenna, causing noise to be transmitted through the user's finger and incorrectly detecting touch events.

Innovation Solution

The implementation of a touch panel design with multiple detection electrodes having different sensitivities to contact and non-contact states, where the ratio of fringe capacitance to total capacitance is varied between electrodes, allowing for the differentiation and elimination of external noise by calculating the difference in detection signals from these electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electrostatic capacitance type touch sensor is used to detect finger touch, then touch detection capability is improved, but erroneous detection due to external noise increases

Engineering Contradiction:

Improvetouch detection capabilityVSAvoiddetection accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The touch panel is divided into multiple detection scan electrodes and multiple detection electrodes, creating multiple independent detection channels. Each electrode pair forms a separate capacitive sensor, allowing the system to segment the detection function across multiple elements rather than relying on a single detection point.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different detection electrodes are designed with different fringe capacitance to total capacitance ratios, creating local variations in sensitivity characteristics. This allows each electrode to have optimized local properties for detecting touches at different positions, while the differential measurement approach ensures that external noise affecting all electrodes equally is cancelled out.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If user's body acts as antenna to catch external noise, then noise transmission to panel increases, but touch detection function remains necessary

Engineering Contradiction:

Improvetouch input functionalityVSAvoidexternal noise interference

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The invention converts the harmful effect of external noise into a beneficial differential measurement approach. By using multiple detection electrodes with different capacitance ratios and calculating the difference between their outputs, the system exploits the fact that external noise affects all electrodes similarly, allowing the noise to be cancelled out in the differential calculation while preserving genuine touch signals.

Inventive Principle:

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

Solution Approach 2:

The multiple detection electrodes act as intermediaries between the external noise environment and the final detection output. By introducing these intermediate sensing elements with varying capacitance characteristics, the system can process signals through differential measurement, effectively filtering out noise that couples uniformly across all electrodes.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This design effectively eliminates erroneous detections caused by external noise, ensuring accurate touch detection by equalizing sensitivities to noise between electrodes and enhancing the reliability of touch input systems.

Implementation Method 1

A popularized touch sensor is, for example, of an electrostatic capacitance type. A touch sensor of this type catches, by a capacitive element, a change occurring in the surface electric field of a panel when a touch panel is touched with a finger or the like

Methodology Applied

Scientific EffectElectrostatic capacitance: Capacitance

Implementation Method 2

A ratio of fringe capacitance to total capacitance between one or more selected detection scan electrodes and the first detection electrode is different from a ratio of fringe capacitance to total capacitance between the one or more selected detection scan electrodes and the second detection electrode

Methodology Applied

Scientific EffectFringe capacitance: Capacitance

Data Source

PatentUS11847287B2Touch panel, display panel, and display unit

Publication Date: 2023.12.19 MAGNOLIA WHITE CORP

AI summary

A touch panel, a display panel, and a display unit achieving prevention of erroneous detection caused by external noise. The touch panel includes: a plurality of detection scan electrodes extending in a first direction and a plurality of detection electrodes facing the plurality of detection scan electrodes and extending in a second direction which intersects the first direction. The one or more selected detection scan electrodes are selected, in a desired unit, from the plurality of detection scan electrodes, to be supplied with a selection pulse, and each of the first and the second detection electrodes is selected from the plurality of detection electrodes.