Variable Frequency Touch Driving Signal for EMI Immunity
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Solution Overview
Problem
Conventional touch display devices suffer from deteriorated touch sensitivity due to electromagnetic interference (EMI), which often results in a poor signal-to-noise ratio (SNR), a critical performance factor for touch sensitivity.
Innovation Solution
The implementation of a touch display device with a touch driving signal whose frequency is changed over time, synchronized with touch driving timing, to improve immunity to EMI and maintain a high SNR, utilizing a touch driving circuit and controller that generates a reference signal with a frequency change pattern matching the touch driving signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional touch driving signal with fixed frequency is used, then the device structure is simple, but electromagnetic interference deteriorates touch sensitivity and signal-to-noise ratio
Solution Approach 1:
The patent applies the dynamics principle by changing the frequency of the touch driving signal over time rather than using a fixed frequency. The frequency modulation creates a time-varying signal that avoids stationary electromagnetic interference patterns, thereby improving touch sensitivity and signal-to-noise ratio while maintaining device simplicity
Solution Approach 2:
The patent implements parameter changes by modulating the frequency parameter of the touch driving signal. The frequency is varied according to a predetermined pattern (e.g., sinusoidal modulation) to shift the signal away from interference frequencies, resolving the contradiction between maintaining simple device structure and improving reliability against electromagnetic interference
2Reliability
If the frequency of touch driving signal is changed over time, then immunity to EMI is improved and SNR is enhanced, but device complexity increases
Solution Approach 1:
The patent applies periodic action by using a predetermined frequency modulation pattern that repeats over time. This periodic frequency variation systematically avoids electromagnetic interference while using simple circuit implementation, thereby improving EMI immunity without significantly increasing device complexity
Solution Approach 2:
The touch driving circuit generates its own frequency-modulated signal using internal components without requiring external complex signal generation equipment. The circuit self-regulates the frequency modulation to achieve EMI rejection, improving reliability while minimizing the increase in device complexity
Data Source
AI summary
The present disclosure relates to a touch display device, a method of driving the touch display device, a touch driving circuit, and a touch controller, for sensing a touch using a touch driving signal whose frequency is changed in sync with a touch driving timing. According to the embodiments of the present disclosure, it is possible to have a high signal-to-noise ratio as well as improved immunity to the EMI, and acquire improved touch sensitivity.