Capacitive Sensor Waveform Timing for Interference Reduction
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Solution Overview
Problem
Capacitive sensing devices face interference issues due to multiplexed electrodes, which affect the accuracy and reliability of input detection in proximity sensor devices.
Innovation Solution
The method involves transmitting independent waveforms over non-overlapping time periods and processing resulting signals to obtain independent capacitive measurements, using a processing system with transmitters and receivers configured to handle multiple sensor electrodes and demodulate signals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple waveforms are transmitted simultaneously over overlapping time periods to improve productivity, then the sensing speed increases, but interference between waveforms increases and measurement precision deteriorates
Solution Approach 1:
The patent applies periodic action by transmitting waveforms in non-overlapping time periods, creating a time-division multiplexing scheme where each waveform is transmitted during its designated time slot. This periodic transmission pattern eliminates interference between multiple waveforms while maintaining continuous sensing operation, thereby preserving measurement precision while achieving improved productivity through efficient time utilization.
2Measurement precision
If independent waveforms are transmitted over non-overlapping time periods to reduce interference, then measurement precision improves, but device complexity increases due to multiple transmitters and receivers
Solution Approach 1:
The patent applies segmentation by dividing the sensing operation into separate time periods, with each period dedicated to a specific waveform transmission. This temporal segmentation allows independent processing of each waveform's resulting signal, simplifying the overall system architecture by eliminating the need for complex interference cancellation algorithms while maintaining high measurement precision through dedicated time slots for each sensing operation.
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 reduces interference susceptibility and enhances the accuracy of capacitive measurements, improving the reliability of input detection in capacitive sensing devices.
Implementation Method 1
a first receiver configured to receive a first resulting signal from a first sensor electrode of the plurality of sensor electrodes in response to capacitive coupling of the first waveform to the first sensor electrode
Data Source
AI summary
An example method of capacitive sensing includes: transmitting a first waveform over a first time period; transmitting a second waveform over a second time period, wherein the second waveform is independent of the first waveform, and wherein at least a portion of the second time period does not overlap the first time period; receiving, from sensor electrodes, a first resulting signal in response to capacitive coupling of the first waveform and a second resulting signal in response to capacitive coupling of the second waveform; and processing the second resulting signal over at least a portion of the first time period, and the second time period, to obtain independent capacitive measurements.