Touch Gesture Detection Using Vibration and Electrostatic Validation
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Solution Overview
Problem
Existing touch detection systems in mobile devices face issues such as mechanical button failure due to structural weakness, environmental interference with capacitive sensors, and high energy consumption with touch-screen technology, leading to inaccurate and costly solutions.
Innovation Solution
A system using an accelerometer and an electrostatic charge variation sensor to detect touch gestures by filtering vibration signals through a high-pass filter, identifying peaks and stationarity conditions, and validating touch events based on predefined thresholds and electrostatic charge variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If capacitive sensors are used to replace mechanical buttons, then structural strength and water resistance are improved, but reliability deteriorates due to environmental electrical charge interference
Solution Approach 1:
The patent introduces an electrostatic charge variation sensor as an intermediary detection mechanism. Instead of directly detecting touch through capacitive changes (which are susceptible to environmental interference), the system uses the electrostatic charge variation sensor to detect changes in electrostatic charge caused by touch gestures. This intermediary approach filters out environmental electrical charge interference while maintaining the benefits of solid-state button design.
2Ease of manufacture
If MEMS accelerometers are used to detect touch gestures, then mechanical button functionality is replaced, but false touch detection increases due to body movements
Solution Approach 1:
The patent segments the detection function into two independent sensors: an accelerometer for detecting vibration patterns and an electrostatic charge variation sensor for detecting contact presence. By dividing the detection task, the system can cross-validate signals from both sensors to distinguish genuine touch gestures from false positives caused by body movements, thereby improving reliability while maintaining the buttonless design.
3Measurement precision
If touch-screen technology is used for gesture detection, then detection accuracy is improved, but energy consumption and cost increase
Solution Approach 1:
The patent employs low-cost, low-power electrostatic charge variation sensors and accelerometers instead of expensive touch-screen technology. These sensors consume minimal energy and can be implemented in devices where full touch-screen capability is not required, providing an economical alternative that maintains adequate detection accuracy for basic gesture recognition while significantly reducing energy consumption and cost.
4Object-affected harmful factors
If high-pass filtering is applied to accelerometer signals, then low frequency noise is reduced, but false positives increase from unwanted vibrations
Solution Approach 1:
The patent implements a feedback mechanism where the electrostatic charge variation sensor provides confirmation feedback to validate accelerometer-detected vibrations. When the accelerometer detects potential touch vibrations through high-pass filtering, the system checks for corresponding electrostatic charge variations. This feedback loop confirms genuine touch events and filters out false positives from unwanted vibrations, resolving the contradiction between noise reduction and false positive reduction.
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 system provides accurate and reliable touch detection with low energy consumption, reducing false positives and enabling cost-effective implementation across various devices.
Implementation Method 1
an accelerometer, operatively coupled to the processing unit, configured to detect a vibration at said detection surface and generate a corresponding vibration signal
Implementation Method 2
The filtering is, in particular, obtained through a digital 'Slope' filter. Therefore, with reference to Figures 1A and 1B, the raw signal provided by the accelerometer
Implementation Method 3
an electrostatic charge variation sensor, operatively coupled to the processing unit, configured to detect an electrostatic charge variation at said detection surface
Data Source
Figure 1A~3
Figure 4~5
Figure 6~8
AI summary
System (1) for detecting a touch gesture of a user on a detection surface (102), comprising: a processing unit (2); and an accelerometer (4) to detect a vibration at the detection surface and generate a vibration signal (Sacc_raw). The processing unit is configured to: acquire the vibration signal, detect, in the vibration signal, a signal characteristic (p1, p2) which can be correlated to the touch gesture of the user, detect, in the vibration signal, a stationarity condition preceding and/or following the detected signal characteristic, and validate the touch gesture in the event that both the signal characteristic and the stationarity condition have been detected. An electrostatic charge sensor (6) may also be used as a further parameter to validate the touch gesture.