Capacitive Touchscreen Thresholding for Electrotactile Cross-Coupling
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Solution Overview
Problem
Integrating capacitive touchscreen technology with electrotactile haptic feedback in portable electronic devices poses a technical challenge due to capacitive cross-coupling issues, which can lead to erroneous touch input signals and accidental triggering of sensors.
Innovation Solution
Incorporating an electrotactile layer with strategically designed apertures that reduce capacitive cross-coupling between the electrotactile layer and capacitive touch sensors, allowing for effective haptic feedback while maintaining accurate touch input detection by setting appropriate detection thresholds and controlling potentials applied to both layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an electrotactile layer is integrated with capacitive touch sensors to provide haptic feedback, then haptic feedback capability is improved, but capacitive cross-coupling causes erroneous touch input signals and sensor misactivation
Solution Approach 1:
The electrotactile layer is divided into multiple independently controllable electrode segments corresponding to different touch sensor regions. This segmentation allows selective activation of electrotactile electrodes, reducing capacitive cross-coupling between adjacent sensors and preventing erroneous touch signals while maintaining haptic feedback capability.
Solution Approach 2:
Different detection thresholds are applied to different capacitive touch sensors based on their local characteristics and proximity to electrotactile electrodes. This local quality adjustment compensates for varying degrees of capacitive cross-coupling across the touchscreen surface, improving overall detection accuracy.
2Measurement precision
If detection threshold is lowered to improve sensitivity to light touch, then touch detection sensitivity is improved, but false positives increase due to capacitive cross-coupling from electrotactile layer
Solution Approach 1:
The system performs preliminary characterization of capacitive cross-coupling effects during manufacturing or initial setup, storing compensation data for each touch sensor. This preliminary action enables the system to pre-adjust detection thresholds and apply appropriate compensation algorithms, allowing low thresholds for sensitivity while filtering out false positives from electrotactile cross-coupling.
Solution Approach 2:
The system continuously monitors touch sensor signals and uses feedback from the electrotactile electrode activation states to dynamically adjust detection decisions. When electrotactile electrodes are activated, the system compensates for the known capacitive coupling effects in real-time, maintaining accurate touch detection even with low detection thresholds.
3Power
If electrotactile electrodes are positioned close to capacitive touch sensors to enhance haptic feedback, then haptic feedback effectiveness is improved, but capacitive cross-coupling increases causing sensor interference
Solution Approach 1:
The system dynamically controls the activation and voltage levels of electrotactile electrodes based on detected touch events. During normal operation, electrotactile electrodes remain inactive or at low voltage to minimize cross-coupling. Upon detecting a touch, the system activates specific electrotactile electrodes with appropriate voltage levels to provide haptic feedback, thereby maintaining close positioning for effectiveness while reducing interference through dynamic control.
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 inputs and provision of haptic feedback without causing unintended sensor activation, enhancing user interaction with portable electronic devices by minimizing capacitive cross-coupling effects.
Implementation Method 1
an electrotactile surface which takes advantage of capacitive coupling to the user's skin to create a variable frictional force on the touchscreen panel
Implementation Method 2
compare the capacitance associated with a capacitive touch sensor of the array against a respective detection threshold to determine whether or not a touch input has occurred at the capacitive touch sensor by a stylus in capacitive coupling proximity
Data Source
AI summary
An apparatus including a processor and a memory including computer program code. The memory and the computer program code are configured to cause the apparatus to, for an array of capacitive touch sensors with a proximally positioned electrotactile layer, compare the capacitance associated with a capacitive touch sensor of the array against a respective detection threshold to determine whether or not a touch input has occurred at the capacitive touch sensor by a stylus in capacitive coupling proximity to the capacitive touch sensor. The detection threshold of one or more capacitive touch sensors of the array is set to be sufficient to inhibit the erroneous generation of a touch input signal at the one or more respective capacitive touch sensors caused by capacitive cross-coupling, via the electrotactile layer, to the capacitive touch sensor which is in capacitive coupling proximity to the stylus.