Capacitance Image Touchless Gesture Detection in Large Displays
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Solution Overview
Problem
Existing touch screen technologies face challenges in accurately detecting touchless gestures and distinguishing between desired and undesired touches, particularly in large touch screen displays with integrated electrodes.
Innovation Solution
The implementation of a touch screen display system that utilizes capacitance image data to sense touches and touchless gestures. This system includes drive sense circuits coupled with electrodes to detect changes in capacitance, allowing for the generation of capacitance images that identify the location and nature of touches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If capacitance-based touch detection is used in large touch screen displays, then touch input capability is enabled, but difficulty in distinguishing between desired and undesired touches increases
Solution Approach 1:
The patent segments the touch detection process into multiple independent measurements: self-capacitance measurement at each electrode, mutual capacitance measurement between electrode pairs, and proximity capacitance measurement. By dividing the detection into separate capacitive channels, the system can analyze different touch characteristics independently and distinguish between finger touches, pen touches, and undesired touches based on their unique capacitance signatures.
Solution Approach 2:
The patent utilizes parameter changes in capacitance values to differentiate touch types. By measuring self-capacitance (Cs), mutual capacitance (Cm), and proximity capacitance (Cp) and analyzing their relationships, the system detects distinct parameter patterns for different touch scenarios. For example, finger touches produce specific capacitance changes compared to pen touches or undesired touches, allowing discrimination through parameter analysis.
2Adaptability or versatility
If integrated electrodes are used throughout the display area, then touchless gesture detection is enabled, but device complexity increases
Solution Approach 1:
The patent implements universal electrodes that perform multiple functions: they serve as both display electrodes for showing content and as sensing electrodes for detecting touches and touchless gestures. The same electrode structure is used across the entire display area for both visual output and input detection, eliminating the need for separate sensor regions and enabling touchless gesture detection without adding dedicated hardware components.
Solution Approach 2:
The patent merges the display function and touch sensing function into a single integrated electrode system. By combining the visual display electrodes with the touch detection electrodes, the system achieves multi-functionality where the same physical structure supports both showing content and detecting user interactions including touchless gestures, thereby reducing overall device complexity despite the enhanced capabilities.
3Measurement precision
If multiple capacitance measurements are performed to distinguish touch types, then detection accuracy is improved, but processing time increases
Solution Approach 1:
The patent performs preliminary capacitance measurements by continuously monitoring self-capacitance, mutual capacitance, and proximity capacitance values before a complete touch analysis is required. By pre-capturing these capacitance parameters and maintaining them in ready state, the system reduces the processing time needed when actual touch detection is required, as the foundational measurement data is already available for rapid analysis.
Solution Approach 2:
The patent implements feedback mechanisms where capacitance measurement results are continuously analyzed and used to adjust subsequent measurement strategies. The system monitors capacitance changes in real-time and uses this feedback to determine when detailed touch analysis is necessary versus when simplified detection suffices, thereby optimizing processing time while maintaining high detection accuracy through adaptive measurement based on feedback from ongoing capacitance monitoring.
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 effectively detects and distinguishes between finger touches, pen touches, and touchless gestures, improving the accuracy and reliability of touch input in large touch screen displays.
Implementation Method 1
drive sense circuits coupled with electrodes to detect changes in capacitance
Data Source
AI summary
A touch screen display includes a plurality of electrodes configured to facilitate touch sense functionality based on electrode signals having a drive signal component and a receive signal component, a plurality of drive-sense circuits coupled to at least some of the plurality of electrodes to generate a plurality of sensed signals, and a processing module. The processing module is configured to cause the touch screen display to receive the plurality of sensed signals. A stream of capacitance image data associated with the plurality of cross points is generated based on the plurality of sensed signals. The stream of capacitance image data is processed to detect a touchless gesture.