Capacitive Touch System Frequency Division Multiplexing Noise Reduction
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Solution Overview
Problem
Capacitive touch systems face interference from noise in electronic devices, leading to degraded detection accuracy, particularly in applications like liquid crystal displays.
Innovation Solution
A capacitive touch system using frequency division multiplexing to input mixed signals with multiple driving frequencies into each input channel, which are modulated and filtered to generate detection matrices, reducing noise interference, power consumption, and detection interval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capacitive sensing is used with single frequency drive signals, then the system structure is simple, but noise interference from electronic devices degrades detection accuracy
Solution Approach 1:
The patent segments the drive signal into multiple frequency components through frequency division multiplexing. By using multiple driving frequencies instead of a single frequency, the system can distinguish between noise and actual touch signals more effectively, thereby improving detection accuracy in noisy environments.
Solution Approach 2:
The patent changes the frequency parameter of the drive signal by modulating it with multiple frequencies. This parameter change allows the system to differentiate between noise (which typically occupies specific frequency ranges) and genuine touch signals, thus reducing noise interference and improving measurement precision.
2Measurement precision
If multiple driving frequencies are used through frequency division multiplexing, then noise interference is reduced and detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent implements a multi-functional control chip that can generate multiple driving frequencies, perform modulation, and process detection signals within a single integrated device. This multi-functionality approach reduces the need for separate components for each function, thereby managing system complexity while achieving improved detection accuracy through multiple frequencies.
Solution Approach 2:
The patent uses periodic modulation of drive signals at different frequencies, where each frequency component operates in a periodic manner. This structured periodic action simplifies the processing requirements compared to arbitrary multi-frequency signals, as the periodic nature allows for more efficient signal generation and processing algorithms.
3Measurement precision
If multiple driving frequencies are input concurrently, then detection accuracy is enhanced, but power consumption increases
Solution Approach 1:
The patent merges multiple drive signals at different frequencies into a single modulated signal that can be transmitted through the same electrode pairs. By combining the generation and transmission of multiple frequencies into one integrated process, the system achieves improved detection accuracy while avoiding the proportional increase in power consumption that would result from using separate signal paths for each frequency.
Solution Approach 2:
The patent maintains continuous drive signals at multiple frequencies simultaneously rather than switching between them sequentially. This continuous multi-frequency operation improves detection accuracy by providing constant monitoring across multiple frequency bands, while the efficient modulation technique ensures that power consumption remains manageable compared to sequential scanning approaches.
4Measurement precision
If frequency division multiplexing is used to reduce noise interference, then detection accuracy improves, but the detection interval increases
Solution Approach 1:
The patent employs periodic modulation at multiple frequencies where each frequency component completes its cycle within a defined period. This structured periodic action allows the system to process multiple frequency components efficiently within a single detection frame, improving detection accuracy without proportionally increasing the detection interval as would occur with sequential frequency scanning.
Solution Approach 2:
The patent performs preliminary modulation of drive signals with multiple frequencies before they are applied to the sensing electrodes. This preliminary preparation of multi-frequency signals allows the system to gather detection data across multiple frequency bands simultaneously, thereby improving detection accuracy without extending the detection interval, as the multi-frequency analysis is prepared in advance rather than processed sequentially.
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
The system effectively enhances detection accuracy by filtering noise and optimizing power usage through the use of frequency division multiplexing, improving the reliability of touch detection in noisy environments.
Implementation Method 1
Electric field can be generated between the first electrode 91 and the second electrode 92 so as to transfer charges to the second electrode 92
Implementation Method 2
the conductor can disturb the electric field between the first electrode 91 and the second electrode 92 so that the amount of charge transfer Y′ is reduced
Data Source
AI summary
A capacitive touch system including a drive end, a capacitive touch sensing device and a detection end is provided. The drive end inputs a modulated drive signal into an input channel of the capacitive sensing device, wherein the modulated drive signal includes a plurality of driving frequencies. The detection end detects a detection signal of an output channel of the capacitive sensing device and generates a two-dimensional detection vector corresponding to each of the driving frequencies.