Capacitive Touch Shield Electrode for 3D Position Detection
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Solution Overview
Problem
Current capacitive touch sensitive displays struggle to accurately detect the three-dimensional position of a user's finger, particularly when it is close to but not touching the sensing area, due to interference from stray capacitance and noise.
Innovation Solution
The apparatus employs a plurality of capacitive sensor electrodes distributed over a sensing area, combined with a shield electrode and conductive traces, which are formed from transparent conductive materials like Indium-Tin-Oxide or silver nanowires, to reduce stray capacitance and enable both two-dimensional and three-dimensional sensing by detecting variations in capacitance with improved noise shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shield electrode is added to reduce noise and stray capacitance, then measurement precision improves, but device complexity increases
Solution Approach 1:
The shield electrode is integrated with the transparent conductor layer that already forms part of the touch sensor structure. This merging approach allows the shield function to be added without creating a completely separate component, thereby reducing the increase in device complexity while still achieving noise reduction and improved measurement precision
Solution Approach 2:
The transparent conductor serves as an intermediary element that simultaneously functions as both the shield electrode and part of the sensing structure. This intermediary role allows the shield to reduce stray capacitance and noise while maintaining compatibility with the existing sensor architecture, balancing the trade-off between precision improvement and complexity increase
2Illumination intensity
If transparent conductive materials are used for shield electrode and traces, then visibility and aesthetics improve, but electrical conductivity decreases
Solution Approach 1:
The patent employs transparent conductive materials such as indium tin oxide (ITO) or silver nanowires that combine optical transparency with electrical conductivity. These composite materials allow the shield electrode and conductive traces to maintain visibility and aesthetic appearance while providing sufficient electrical conductivity for effective noise shielding and signal transmission
Solution Approach 2:
The patent optimizes the thickness, composition, and structural configuration of the transparent conductive materials to achieve the desired balance between transparency and conductivity. By adjusting these parameters, the shield electrode and traces can provide adequate electrical performance for noise reduction while maintaining the visual clarity required for display applications
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 configuration allows for precise detection of the (x, y) position of a finger when touching and (x, y, z) position when close to the sensing area, enhancing the accuracy and speed of touch input recognition while minimizing RC delays and stray capacitance effects.
Implementation Method 1
a shield electrode 12 overlying, in the sensing area 8, conductive traces 10
Implementation Method 2
The capacitive sensor electrodes sense a proximal grounded object such as a user's finger touching the sensing area
Data Source
Figure 1~7C
Figure 2~3
Figure 4~5
AI summary
An apparatus comprising: an array of capacitive sensor electrodes comprising a plurality of distinct capacitive sensor electrodes distributed over a sensing area; conductive traces connected to respective ones of the plurality of distinct capacitive sensor electrodes; and a shield electrode overlying, in the sensing area, conductive traces.