Capacitance Module Multi-Axis Measurement Noise Reduction
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Solution Overview
Problem
Mutual capacitance touch sensors are susceptible to noise, which reduces their accuracy in determining the x, y position of user input.
Innovation Solution
The system includes a first set of electrodes and a second set of electrodes transversely oriented from the first set, with a processor executing programmed instructions to activate and measure capacitance changes in alternating portions of the electrodes, using electrical signals that can be in phase or out of phase with each other.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If simultaneous sampling of all sense electrodes is used to reduce noise susceptibility, then noise reduction is achieved, but measurement time increases
Solution Approach 1:
The patent divides the set of sense electrodes into multiple groups that are sampled sequentially rather than simultaneously. This segmentation allows the system to maintain noise reduction benefits while reducing the time required for complete sampling by processing electrodes in manageable segments.
Solution Approach 2:
The patent implements periodic sampling where different groups of sense electrodes are activated and sampled in alternating time periods. This periodic approach enables continuous operation with reduced noise susceptibility while maintaining efficient time utilization through structured sampling intervals.
2Productivity
If electrical signals are transmitted through all electrodes simultaneously, then measurement speed increases, but constructive interference and noise increase
Solution Approach 1:
The patent segments the electrode transmission process by activating different groups of sense electrodes at different time intervals rather than all electrodes simultaneously. This prevents constructive interference between signals while maintaining efficient measurement speed through parallel processing of electrode groups.
Solution Approach 2:
The patent employs periodic activation of electrode groups with alternating time slots. This periodic transmission pattern eliminates signal interference by ensuring that not all electrodes transmit simultaneously, while maintaining high productivity through systematic rotation between active and inactive groups.
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 constructive interference that contributes to noise, improving the accuracy of user input detection by identifying the location based on the measurement with less noise.
Implementation Method 1
a mutual capacitance touch sensor functions by applying an electrical signal to a transmit electrode and sampling a capacitance change from a sense electrode to determine an x, y position of user input
Implementation Method 2
Transmitting the electrical signals out of phase with each other may have the characteristic of reducing constructive interference that may contribute to noise
Data Source
AI summary
A device may include a first set of electrodes; a second set of electrodes transversely oriented from the first set of electrodes; and a processor and memory, where the memory has programmed instructions to cause the processor, when executed to: activate a first portion of electrodes in the first set, measure a first resulting capacitance from activating the first portion of electrodes with at least some electrodes of the second set, activate a second portion of electrodes in the second set, and measure a second resulting capacitance from activating the second portion of electrodes with at least some electrodes of the first set.