Touch Detection Noise Suppression via Frequency Hopping
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Solution Overview
Problem
Current methods fail to effectively address both liquid crystal display module (LCM) interferences and common mode interferences in touch control systems, hindering miniaturization and thinness advancements and requiring complex computation for capacitive touch screens.
Innovation Solution
A noise suppression method that involves sequentially driving a touch detection system with all supported frequencies, detecting interference strength values, and frequency-hopping to the driving frequency with the minimum interference strength, using a system with a driving unit, drive control unit, interference detecting unit, and frequency-hopping unit to minimize signal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shielding layer is added to avoid LCM interferences, then anti-interference performance is improved, but product structure becomes more complex and miniaturization is hindered
Solution Approach 1:
The patent extracts and eliminates the shielding layer from the product structure by adopting a differential scanning architecture that inherently rejects common-mode interference. The interference rejection is achieved through circuit topology and scanning methodology rather than physical shielding, thereby removing the problematic component while maintaining anti-interference performance.
Solution Approach 2:
The patent replaces the mechanical/physical shielding layer with an electrical/differential signaling system. By using differential scanning and capacitance difference measurement, the system achieves interference rejection through electrical means rather than physical barriers, thus avoiding structural complexity.
2Reliability
If circuit structure is improved to avoid common mode interferences, then anti-interference capability is improved, but computation complexity increases
Solution Approach 1:
The patent segments the scanning process into independent row and column operations, where only one row or one column is scanned at a time against a benchmark. This segmentation simplifies the computation by avoiding the need to process multiple rows or columns simultaneously, reducing the computational burden while maintaining differential interference rejection.
Solution Approach 2:
The patent applies partial action by scanning only one row or one column at a time rather than processing the entire matrix simultaneously. This partial scanning approach, combined with benchmark comparison, achieves effective interference rejection with reduced computation compared to full matrix processing.
3Reliability
If separate methods are used to overcome LCM and common mode interferences, then individual interference types are addressed, but overall system complexity increases and versatility is reduced
Solution Approach 1:
The patent implements a universal differential scanning architecture that simultaneously handles both LCM interference and common mode interference through a single unified approach. The differential measurement technique and benchmark comparison method serve multiple functions: rejecting common-mode signals, eliminating LCM interference, and working across different touch screen configurations, thereby enhancing versatility while maintaining reliability.
Data Source
AI summary
The present invention is applicable to the technical field of touch control. Provided are a touch detection system and a noise suppression method therefor. The method includes the steps of: sequentially driving a touch detection system with all driving frequencies that the touch detection system supports, and detecting a currently existing interference strength value when driving with each driving frequency; and frequency-hopping to the driving frequency corresponding to the minimum interference strength value, and driving the touch detection system with the driving frequency corresponding to the minimum interference strength value to perform a normal operation. By detecting an interference strength value at each driving frequency and then using the driving frequency corresponding to the minimum interference strength value as an operating frequency of a touch terminal, the present invention minimizes the signal interference of a touch detection system.