Capacitive Sensor Array Contact Tracking via Totem Pole Pattern
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Solution Overview
Problem
Current touch-sensor technologies face challenges in accurately detecting and tracking multiple touches and large contacts on capacitive sensor arrays, particularly in determining the centroid position and handling noise and interference, which affects user interaction and accuracy.
Innovation Solution
The implementation of a capacitive sensor array with a totem pole pattern, utilizing a processing device to measure capacitance changes across a matrix of electrodes, and employing algorithms like the Hungarian Algorithm for contact tracking, along with dynamic noise threshold determination and Gaussian curve interpolation, to enhance touch detection and tracking precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional capacitance sensing methods are used, then the system is simple to manufacture, but the accuracy of detecting and tracking multiple touches and large contacts deteriorates
Solution Approach 1:
The sensor array is divided into multiple independently addressable sensor elements arranged in a matrix pattern, allowing individual measurement of capacitance changes at each element. This segmentation enables precise localization of multiple touches and large contacts by measuring capacitance variations across discrete sensor elements rather than as a single aggregate signal.
Solution Approach 2:
The patent transitions from traditional single-axis or simple multi-axis sensing to a two-dimensional matrix array of sensor elements. This dimensional expansion allows simultaneous detection and independent tracking of multiple contact points across the surface, enabling accurate centroid calculation and contact differentiation that was not possible with simpler sensor configurations.
2Measurement precision
If algorithms like Hungarian Algorithm and Gaussian curve interpolation are employed, then contact tracking precision improves, but processing complexity increases
Solution Approach 1:
The system performs preliminary scanning of the sensor array to identify potential contact regions before applying complex tracking algorithms. By pre-identifying areas with significant capacitance changes and using this information to initialize tracking, the system reduces the computational burden of subsequent Hungarian Algorithm execution and Gaussian curve interpolation while maintaining high tracking precision.
Solution Approach 2:
The system continuously monitors capacitance changes across the sensor array and uses this feedback to dynamically adjust tracking parameters and re-identify contacts. This feedback mechanism allows the Hungarian Algorithm to maintain accurate contact identification over time despite variations in touch pressure, position, and duration, while the feedback loop optimizes processing efficiency by focusing computational resources on active contact regions.
3Reliability
If dynamic noise threshold determination is used, then reliability of touch detection improves, but processing time increases
Solution Approach 1:
The system implements periodic noise threshold determination by scanning the sensor array at regular intervals and updating noise baseline values dynamically. This periodic approach allows the system to adapt to changing environmental noise conditions while maintaining efficient processing by only performing threshold calculations at scheduled intervals rather than continuously, thus balancing reliability improvement with processing time constraints.
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 and reliability of touch detection and tracking on capacitive sensor arrays, effectively handling multiple touches and large contacts by reducing noise and enhancing user interaction, while maintaining efficient processing and manufacturability.
Implementation Method 1
a capacitive sensor array with a totem pole pattern, utilizing a processing device to measure capacitance changes across a matrix of electrodes
Data Source
AI summary
The capacitance sensing array comprising a plurality of nodes corresponding to intersections of a first plurality of electrodes with a second plurality of electrodes may be scanned. Capacitance values associated with one or more of the nodes may be measured. The capacitance values may be representative of a touch object proximate to the one or more of the nodes. A peak capacitance value of the capacitance values of one or more of the nodes may be identified. A set of capacitance values comprising cells based on the peak capacitance value may be generated. A portion of the cells of the set are associated with the nodes corresponding to the intersections of the first plurality of electrodes with the second plurality of electrodes and at least one of the cells of the set is associated with a virtual node that does not correspond to the intersections.