Capacitive Sensing Burst Repetition for Short-Term Noise Suppression
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Solution Overview
Problem
Proximity sensor devices face interference from noise emissions, such as those from battery chargers, which impair their sensing capabilities, especially when noise frequencies overlap with the sensing signal frequencies, making it difficult to accurately detect input objects in capacitive sensing systems.
Innovation Solution
A repetitive multi-burst pattern is used for capacitive sensing, where each burst is repeated, allowing for the identification of segments in the resulting signal that are least affected by noise, enabling effective decoding of touch inputs even in the presence of short-term noise emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous sensing waveform is used, then sensing coverage is maintained, but noise interference increases
Solution Approach 1:
The patent applies periodic action by using repetitive multi-burst patterns instead of continuous waveforms. The sensing signal is transmitted in periodic bursts with specific timing structures, allowing the system to maintain sensing capability while creating predictable time windows where noise can be identified and suppressed through comparison of corresponding bursts across different repetitions.
2Measurement precision
If noise suppression techniques are applied, then sensing accuracy improves, but processing complexity increases
Solution Approach 1:
The patent uses copying by transmitting repeated bursts of the sensing waveform and comparing corresponding segments from different repetitions. By creating copies of the sensing signal at different time instances and comparing them to identify consistent patterns versus noise, the system achieves noise suppression through a relatively simple comparison operation rather than complex filtering algorithms.
3Reliability
If burst repetition is implemented, then noise resilience improves, but signal transmission time increases
Solution Approach 1:
The patent applies partial action by using only the clean segments from burst repetitions that are not affected by noise. Instead of requiring complete signal transmissions or processing all burst data, the system identifies and uses only the useful portions of the repeated bursts for decoding, thereby reducing the effective processing time while maintaining noise resilience.
Data Source
AI summary
A processing system is configured to drive a transmitter electrode with a repetitive multi-burst pattern. The repetitive multi-burst pattern includes a first multitude of bursts of a sensing waveform and a second multitude of bursts of the sensing waveform. The second multitude of bursts is a repetition of the first multitude of bursts. The processing system is further configured to receive, from a receiver electrode, a resulting signal in response to the repetitive multi-burst pattern, and identify, in the resulting signal, a segment least affected by a noise, and that temporally coincides with a burst in the first multitude of bursts or a burst in the second multitude of bursts matching the burst in the first plurality of bursts. The processing system is also configured to decode the resulting signal using the segment.