Capacitive Touch Screen Water Compensation via Multi-Frequency Drive Sense Circuit
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Solution Overview
Problem
Current touch screen technologies face challenges in accurately detecting and distinguishing between desired and undesired touches, particularly due to noise interference and variations in capacitance measurements, which can lead to false inputs and reduced user experience.
Innovation Solution
The implementation of a drive sense circuit system that uses multiple frequency components to measure self-capacitance and mutual capacitance, allowing for the differentiation between shielded and unshielded capacitance changes, thereby enhancing touch detection accuracy and noise compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional capacitance measurement methods are used, then the touch screen can detect touches, but noise interference causes false inputs and reduces detection accuracy
Solution Approach 1:
The patent segments the capacitance measurement into multiple frequency components (first frequency component for self-capacitance, second frequency component for mutual capacitance). By measuring at different frequencies and separating the measurements, the system can distinguish between shielded and unshielded capacitance changes, thereby filtering out noise interference and improving touch detection accuracy.
Solution Approach 2:
The patent introduces an intermediary processing mechanism that analyzes both self-capacitance and mutual capacitance measurements across multiple frequency components. This intermediary analysis layer differentiates between desired touches and undesired noise by comparing capacitance changes at different frequencies, effectively filtering out harmful noise interference.
2Reliability
If multiple frequency components are used to measure capacitance, then noise filtering and touch differentiation improve, but device complexity increases
Solution Approach 1:
The drive sense circuit system is designed to perform multiple functions: it measures both self-capacitance and mutual capacitance across multiple frequency components, provides noise filtering, and enables touch differentiation. By making the circuit system multi-functional, the patent achieves improved reliability without requiring separate dedicated circuits for each function, thereby managing complexity more effectively.
Solution Approach 2:
The patent combines multiple measurement functions (self-capacitance measurement, mutual capacitance measurement, noise filtering, and touch differentiation) into a single integrated drive sense circuit system. By merging these functions, the system achieves high reliability through multiple frequency component analysis while avoiding the complexity of having separate independent circuits for each function.
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 approach improves the accuracy of touch detection by effectively filtering out noise and distinguishing between desired and undesired touches, resulting in a more reliable and user-friendly touch screen experience.
Implementation Method 1
uses multiple frequency components to measure self-capacitance and mutual capacitance, allowing for the differentiation between shielded and unshielded capacitance changes
Data Source
AI summary
A capacitive touch screen display operates by: receiving a plurality of sensed signals indicating variations in mutual capacitance associated with a plurality of cross points formed by a plurality of electrodes; generating capacitance image data associated with the plurality of cross points that includes positive capacitance variation data corresponding to positive variations of the capacitance image data from a nominal value and negative capacitance variation data corresponding to negative variations of the capacitance image data from the nominal value; identifying a presence of water on the touch screen display based on the positive capacitance variation data, and the negative capacitance variation data; generating compensated capacitance image data to compensate for effects of the water on the touch screen display in the capacitance image data; and processing the compensated capacitance image data to determine a proximal condition of the touch screen display.