Capacitance Touch Sensor Shield Signal Water Rejection
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Solution Overview
Problem
Capacitance-sensing devices face challenges in distinguishing between finger touches and water drops, leading to false triggering due to similar signal patterns, especially in the presence of water films or drops, which affects reliable operation in harsh conditions.
Innovation Solution
The implementation of a shield signal applied to non-selected sensor elements, creating an equipotential surface that reduces water influence, allowing the capacitance-sensing circuitry to differentiate between water and finger touches by adjusting modulator current calculations, thereby enhancing the signal-to-noise ratio and preventing false detections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitance-sensing circuitry is used to detect finger touches, then touch detection capability is improved, but false triggering occurs when water drops or films are present on the sensor
Solution Approach 1:
The patent applies a shield signal to non-selected sensor elements to create an equipotential surface across the touch panel. This equipotential surface reduces the electric field distortion caused by water drops or films, allowing the capacitance-sensing circuitry to distinguish between water presence and actual finger touches, thereby eliminating false triggering while maintaining touch detection accuracy.
2Reliability
If a shield signal is applied to non-selected sensor elements to reduce water influence, then false triggering is eliminated, but device complexity increases
Solution Approach 1:
The shield signal is applied using the existing sensor element infrastructure and capacitance-sensing circuitry. The same sensor elements that detect finger touches are also used to apply the shield signal to non-selected elements. This multi-functional use of existing components achieves water rejection without requiring separate dedicated shield electrodes or additional hardware, thereby limiting the increase in device complexity.
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 solution effectively reduces water influence on touch-sensing devices, enabling accurate detection of touches while eliminating false triggers caused by water presence, even in harsh conditions, and is applicable to both single-layer and multi-layer designs.
Implementation Method 1
capacitance-sensing circuitry to apply a shield signal to sensor elements
Implementation Method 2
creating an equipotential surface that reduces water influence
Data Source
AI summary
A method and apparatus for reducing water influence on a touch-sensing device is described.