Touch Sensor Noise Prediction with Transmitter-Off Sampling
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Solution Overview
Problem
Existing touch screen systems face challenges in accurately distinguishing between desired and undesired touches due to noise interference, which affects the reliability and precision of touch sensing.
Innovation Solution
Implementing a spatial filter active noise cancellation (ANC) circuit to reduce noise interference by using adaptive filtering techniques, which enhance the signal-to-noise ratio and improve touch detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional touch sensing is used, then the system is simple, but noise interference reduces measurement precision
Solution Approach 1:
The patent introduces an ANC circuit as an intermediary component between the touch sensor and processing system. This circuit includes a noise reference input that accepts a noise reference signal, which is then processed through adaptive filtering to generate a noise cancellation signal. The noise cancellation signal is combined with the touch sensor output to produce a cleaned touch signal, effectively mediating the interaction between noisy sensor data and the processing system while improving measurement precision without requiring complete system redesign
Solution Approach 2:
The ANC circuit implements feedback mechanisms through adaptive filtering where the noise reference signal is continuously processed to generate updated noise cancellation signals. The circuit uses feedback loops to adjust filter coefficients based on the correlation between the noise reference signal and the actual noise in the touch sensor output, enabling dynamic adaptation to changing noise conditions and maintaining optimal noise cancellation performance
2Reliability
If noise cancellation is implemented, then touch detection accuracy improves, but device complexity increases
Solution Approach 1:
The patent segments the touch sensing system into distinct functional modules: the original touch sensor, the ANC circuit with noise reference input, the adaptive filter processing stage, and the output combination stage. This segmentation allows the noise cancellation functionality to be added as a separate module rather than integrating it throughout the entire system, making the complexity localized and manageable while improving overall reliability
Solution Approach 2:
The ANC circuit is designed with multi-functionality to justify its added complexity. It can process different types of noise references (electromagnetic interference, acoustic noise, mechanical vibrations), work with various touch sensor types, and adapt to different noise conditions through adjustable filter parameters. This universality allows a single circuit design to handle multiple noise scenarios, improving reliability across diverse operating conditions without requiring separate specialized circuits for each noise type
Data Source
AI summary
A method for execution by a computing device includes determining to implement a noise prediction and cancellation operation for a touch signal associated with a touch sensor. The method continues during a first time period with turning off a transmitter associated with the touch sensor and obtaining a noise sample of noise associated with the touch sensor, wherein after the first time period is over, the transmitter is turned on. The method continues with generating a noise estimate of the noise based on the noise sample. The method continues during a second time period with obtaining a reduced noise touch signal associated with the touch sensor based on the noise estimate and determining touch data representing a touch of the touch screen based on the reduced noise touch signal, wherein the reduced noise touch signal is produced by subtracting the noise estimate from a current sample of the touch signal.