Capacitive Touch Panel Signal-to-Noise Detection
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Solution Overview
Problem
Touch panels face signal-to-noise ratio issues due to noise interference from display devices, leading to potential malfunctions in detecting touch inputs.
Innovation Solution
A touch panel input device employs a driving signal supplier that applies driving signals with phase differences using Pseudo-Random Bit Stream (PRBS) codes to node capacitors, allowing for improved capacitance detection by summing and comparing sensing signals across different intervals, enhancing noise resistance and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If driving signals are applied to multiple driving signal electrodes simultaneously, then touch panel response speed is improved, but noise interference from display device increases
Solution Approach 1:
The patent applies periodic driving signals with different phases to multiple driving signal electrodes. By using periodic actions with phase differences, the system achieves fast response while the periodic nature allows for noise cancellation through differential measurement, resolving the contradiction between speed and noise interference
Solution Approach 2:
The patent applies driving signals to driving signal electrodes before actual touch detection occurs. This preliminary action establishes a baseline capacitance state that enables subsequent differential measurement, allowing the system to distinguish between normal capacitance variations and noise interference, thus improving response speed while maintaining noise resistance
2Measurement precision
If capacitance detection is performed continuously, then touch input detection accuracy is improved, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent uses feedback by comparing capacitance measurements taken at different time points with different driving signal configurations. The system continuously monitors capacitance changes and uses this feedback to distinguish between genuine touch inputs and noise, maintaining high detection accuracy while preserving signal-to-noise ratio through intelligent signal processing
Solution Approach 2:
The patent applies driving signals to only certain driving signal electrodes at specific time intervals rather than continuously to all electrodes. This partial action reduces the overall noise floor while maintaining sufficient data points for accurate touch detection through selective measurement, resolving the trade-off between detection accuracy and signal-to-noise ratio
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 improves the signal-to-noise ratio, reducing the likelihood of malfunctions and enhancing the accuracy of touch input detection by effectively managing noise interference and phase differences in the driving signals.
Implementation Method 1
At least one among the driving signals which are simultaneously applied to the driving signal electrode has a phase difference from the other driving signals
Implementation Method 2
a touch panel which includes a plurality of node capacitors, each of which is formed by one of a plurality of driving signal electrodes and one of a plurality of sensing signal electrodes
Implementation Method 3
a sensing signal part which receives a sensing signal including information on capacitances of the plurality of node capacitors through the plurality of sensing signal electrodes
Data Source
AI summary
A touch panel input device and an input detection method thereof are provided. A driving signal is controlled to include a plurality of time intervals in which the driving signal is applied to at least one of at least two driving signal electrodes simultaneously driven, and in which the driving signal is not applied to at least one of at least two driving signal electrodes simultaneously driven. A driving signal supplier causes that a combination of the driving signal electrode to which the driving signal is applied in one of the plurality of time intervals and the driving signal electrode to which the driving signal is not applied in the one of the plurality of time intervals is different from a combination of the driving signal electrode to which the driving signal is applied in the other of the plurality of time intervals and the driving signal electrode to which the driving signal is not applied in the other of the plurality of time intervals. At least one among the driving signals which are simultaneously applied to the driving signal electrode has a phase difference from the other driving signals.