Active Stylus Touch Panel Frequency Matching for Accurate Input
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Solution Overview
Problem
Mismatches between modulation and demodulation frequencies in touch panels using active styluses lead to inaccurate and sensitive touch controls, affecting user experience.
Innovation Solution
A touch panel system with a receiver and processor that demodulates writing signals from an active stylus, determines signal abnormalities, and adjusts demodulation frequency to increase energy, thereby matching modulation and demodulation frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed demodulation frequency is used to demodulate writing signals from active stylus, then the device complexity is reduced, but the measurement precision and reliability of touch control deteriorate due to frequency mismatches
Solution Approach 1:
The patent implements dynamic frequency adjustment by monitoring the energy of demodulated writing signals and automatically adjusting the demodulation frequency to match the modulation frequency of the active stylus. This dynamic adaptation resolves the contradiction by maintaining measurement precision through real-time frequency synchronization while keeping the overall system relatively simple through automated feedback control
Solution Approach 2:
The system employs feedback mechanisms by evaluating the energy of demodulated signals and using this information to adjust the demodulation frequency. This closed-loop feedback ensures that frequency mismatches are detected and corrected, maintaining high measurement precision without requiring complex manual calibration procedures
2Reliability
If the demodulation frequency is adjusted to match modulation frequency, then the reliability of touch control is improved, but the device complexity increases due to additional frequency adjustment mechanisms
Solution Approach 1:
The system performs self-adjustment by automatically detecting frequency mismatches through energy evaluation of demodulated signals and correcting its own demodulation frequency without external intervention. This self-service capability improves reliability while minimizing the need for additional external control mechanisms, thereby limiting the increase in device complexity
Solution Approach 2:
The patent changes the demodulation frequency parameter dynamically based on detected signal characteristics. By adjusting this key parameter in response to energy measurements, the system improves reliability through frequency matching while using a relatively simple parameter adjustment approach rather than complex mechanical or electronic frequency synthesis mechanisms
Data Source
AI summary
A touch panel and a control method thereof. The control method is applied to a touch panel to receive controls from an active stylus. The control method comprises using a demodulation frequency to demodulate a writing signal received from the active stylus; determining whether a demodulated writing signal is abnormal or not; and in response to determining the demodulated writing signal to be abnormal, adjusting the demodulation frequency to increase an energy of the demodulated writing signal.