Touch System Frequency Variation for Interference Reduction
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Solution Overview
Problem
Current self-capacitance detection technologies in touch panels suffer from electromagnetic interference due to centralized power distribution at a single frequency, leading to decreased detection accuracy from harmonic waveforms with high-ordered frequencies.
Innovation Solution
A touch system and method that vary the frequencies of transmitting and alternating current shielding signals over time, distributing power across different frequencies during different intervals to avoid centralized power distribution, thereby reducing electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a constant frequency transmitting signal and identical frequency alternating current shielding signal are used, then the waveform matching between transmitting signal and shielding signal improves detection accuracy, but the centralized power distribution at a single frequency generates harmonic waveforms causing electromagnetic interference that decreases detection accuracy
Solution Approach 1:
The patent applies dynamics by making the frequency of the transmitting signal and alternating current shielding signal variable rather than constant. The system dynamically adjusts frequencies across multiple values over time, allowing the shielding signal to maintain waveform matching with the transmitting signal while distributing power across different frequencies to avoid harmonic interference.
Solution Approach 2:
The patent changes the frequency parameter of both the transmitting signal and alternating current shielding signal. By varying the frequency over time and using different frequencies for different scan lines, the system maintains the beneficial waveform matching effect while eliminating the harmful centralized power distribution that causes electromagnetic interference.
2Reliability
If power is centrally distributed at a certain frequency for a long time, then the alternating current shielding signal effectively reduces cross-voltages of parasitic capacitors, but harmonic waveforms with high-ordered frequencies are generated causing electromagnetic interference
Solution Approach 1:
The patent applies periodic action by systematically varying the frequency of transmitting and shielding signals across multiple time intervals. Different frequencies are used for different scan lines and time periods, creating a periodic pattern that distributes power across the frequency spectrum while maintaining the shielding effectiveness needed to reduce parasitic capacitor cross-voltages.
Solution Approach 2:
The system dynamically changes the frequency parameter over time, transitioning from static single-frequency operation to dynamic multi-frequency operation. This allows the shielding signal to adaptively maintain effectiveness while avoiding the generation of sustained harmonic waveforms that cause electromagnetic interference.
3Measurement precision
If the frequency of the alternating current shielding signal is kept identical to the transmitting signal, then cross-voltages of parasitic capacitors are decreased, but electromagnetic interference becomes unavoidable due to centralized power distribution
Solution Approach 1:
The patent changes the frequency parameter relationship between the transmitting signal and alternating current shielding signal. Instead of keeping frequencies identical, the system uses frequencies that are substantially equal at corresponding time points but varies these frequencies across multiple values over time, maintaining the shielding benefit while eliminating electromagnetic interference through frequency distribution.
Solution Approach 2:
The system dynamically adjusts the frequency relationship between transmitting and shielding signals. At any given time point, the frequencies remain matched for effective shielding, but over time the frequencies vary across multiple values, transforming the static identical-frequency approach into a dynamic multi-frequency approach that avoids electromagnetic interference.
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 electromagnetic interference by preventing the concentration of power at a single frequency, enhancing detection accuracy by minimizing harmonic waveforms with high-ordered frequencies.
Implementation Method 1
an alternating current shielding signal can be used for avoiding generations of parasitic capacitors between different scan lines and a sensor
Data Source
AI summary
A method for controlling a touch system capable of reducing electromagnetic interference includes generating a first transmitting signal with a first frequency and a first alternating current shielding signal with the first frequency, transmitting the first transmitting signal to a first scan line of a plurality of scan lines of a touch panel, transmitting the first alternating current shielding signal to the plurality of scan lines exclusive of the first scan line, generating a second transmitting signal with a second frequency and a second alternating current shielding signal with the second frequency, transmitting the second transmitting signal to a second scan line of the plurality of scan lines, and transmitting the second alternating current shielding signal to the plurality of scan lines exclusive of the second scan line.