Capacitive Touch Sensor Layout for Floating-State Signal Detection

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Solution Overview

Problem

Touch input devices with touch sensors struggle to accurately detect touch inputs and positions when in a floating state, leading to signal loss or misinterpretation due to Low Ground Mass (LGM) effects, especially when multiple touches occur.

Innovation Solution

The touch input device incorporates a touch sensor with a plurality of driving and receiving electrodes, along with dummy electrodes, to subtract noise signals from detection signals, allowing accurate touch position detection even in a floating state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a touch sensor is used in a floating state, then the device can be operated without hand holding, but touch signal detection accuracy deteriorates due to LGM effects

Engineering Contradiction:

Improvefloating state operationVSAvoidtouch signal detection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent introduces a reference electrode as an intermediary element that does not form mutual capacitance with driving electrodes. This reference electrode captures LGM noise signals separately, allowing the noise to be subtracted from the detection signals of receiving electrodes, thereby eliminating the harmful LGM effects while maintaining floating state operation capability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the touch sensor into functional groups: driving electrodes that generate electric fields, receiving electrodes that detect touch signals, and reference electrodes that capture noise. This segmentation allows independent optimization of each component's function, enabling the reference electrodes to specifically target and capture LGM noise without interfering with the primary touch detection function

Inventive Principle:

Principle #1Segmentation

2Device complexity

If driving and receiving electrodes are implemented in the same layer or dual layers, then device structure is simplified, but signal detection accuracy deteriorates when device is touched without hand holding

Engineering Contradiction:

Improveelectrode layer structureVSAvoidtouch signal detection reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent segments electrodes into distinct functional groups within the same or dual layer structure: driving electrodes for signal generation, receiving electrodes for touch detection, and reference electrodes for noise capture. This functional segmentation maintains structural simplicity while enabling reliable touch signal detection in floating state through noise subtraction

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If dummy receiving electrodes are added to capture LGM noise, then touch detection accuracy in floating state is improved, but device complexity increases

Engineering Contradiction:

Improvetouch position detection accuracyVSAvoidelectrode configuration

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the electrode system into functional groups, adding reference electrodes that specifically capture LGM noise. These reference electrodes are strategically positioned to monitor noise without interfering with primary touch detection, improving measurement precision while maintaining manageable device complexity through clear functional segmentation

Inventive Principle:

Principle #1Segmentation

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 solution enables reliable detection of touch signals, including multiple touches and cross touches, in both grip and floating states, improving the accuracy and functionality of touch input devices.

Implementation Method 1

a first detection signal output from a predetermined receiving electrode that forms mutual capacitance with the predetermined driving electrode among the plurality of receiving electrodes

Methodology Applied

Scientific EffectMutual capacitance: Capacitance

Implementation Method 2

a second detection signal output from a dummy receiving electrode that does not form mutual capacitance with the predetermined driving electrode among the plurality of dummy receiving electrodes

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS12468412B2Touch input device that outputs a detection signal based on first and second capacitance information

Publication Date: 2025.11.11 HIDEEP INC

AI summary

A touch input device including a touch surface, comprises: a touch sensor which is disposed under the touch surface and includes a plurality of driving electrodes, a plurality of receiving electrodes, and a plurality of dummy receiving electrodes; and a touch detection unit configured to detect a touch position of an object on the touch surface based on a detection signal output from the plurality of receiving electrodes of the touch sensor.