Capacitive Sensor Adaptive Scanning to Reduce Motion Artifacts
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Solution Overview
Problem
Traditional capacitive sensing methods in input devices suffer from significant delays and increased latency due to the need to scan the entire trans-capacitance image for every frame, leading to under-sampling of input object signals and potential motion artifacts.
Innovation Solution
The implementation of adaptive scanning, where electrodes are driven and scanned in subsets based on previous detections, alternating axes to reduce unnecessary scanning and improve efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the entire trans-capacitance image is scanned for every frame, then complete coverage of the sensing region is achieved, but scanning time increases significantly and latency increases
Solution Approach 1:
The patent segments the electrode array into multiple subsets that can be scanned in different phases. Instead of scanning all electrodes sequentially for every frame, the system divides the sensing region into segments and scans only the relevant segments, reducing total scanning time while maintaining detection completeness through systematic coverage across multiple phases.
Solution Approach 2:
The patent performs preliminary actions by scanning electrodes in a first phase to identify input objects, then uses this information to determine which electrodes need to be scanned in subsequent phases. This preliminary scanning establishes a baseline that optimizes subsequent scanning operations, reducing redundant scanning and overall time loss.
2Measurement precision
If the entire electrode array is scanned every frame, then all input objects are detected, but the maximum scanning rate is limited and latency increases
Solution Approach 1:
The patent implements dynamic scanning where the scanning pattern adapts based on detected input objects. The system determines which electrodes to scan in subsequent phases based on where input objects were detected in previous phases, allowing the scanning rate to adjust dynamically to actual usage patterns rather than scanning at a fixed maximum rate regardless of conditions.
Solution Approach 2:
The patent applies local quality by focusing scanning resources on specific electrode regions where input objects are detected. Instead of uniformly scanning the entire array at high speed, the system concentrates scanning efforts on local regions of interest, improving effective scanning rate for relevant areas while maintaining overall detection accuracy.
3Measurement precision
If traditional scanning methods are used, then complete signal sampling is achieved, but motion artifacts are introduced due to under-sampling and processing delays
Solution Approach 1:
The patent uses feedback from detecting input objects in one phase to optimize scanning in subsequent phases. The system analyzes which electrodes detected input objects and uses this feedback information to determine scanning priorities, allowing faster response to motion changes and reducing motion artifacts caused by delayed or incomplete sampling.
Solution Approach 2:
The patent employs periodic scanning phases where electrodes are scanned in alternating sequences. By organizing scanning into periodic phases that can be optimized based on detected objects, the system achieves more frequent effective samples during critical periods, improving signal completeness and reducing motion artifacts compared to single-pass traditional scanning.
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 significantly reduces scanning time and minimizes motion artifacts by focusing scanning efforts only on detected input objects, enhancing the responsiveness and accuracy of capacitive sensors.
Implementation Method 1
Proximity sensor devices utilize one or more electrical techniques to determine the presence, location and/or motion of an input object, such as a capacitive sensing technique
Data Source
AI summary
A method for performing a scanning process using adaptive scanning, comprising: driving, by a processing system of an input device, one or more of a first set of electrodes to generate first sensing signals that are detectable by a second set of electrodes; obtaining first resulting signals associated with the first sensing signals via the second set of electrodes; determining, based on the first resulting signals, a first subset of the second set of electrodes that detected an input object on a display device; driving one or more of the first subset of the second set of electrodes that detected the input object to generate second sensing signals that are detectable by the first set of electrodes; and obtaining second resulting signals associated with the second sensing signals via the first set of electrodes.