Touch Driving Circuit With Adaptive Uplink Amplitude for EMI Control
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Solution Overview
Problem
Touch display devices face challenges in providing pen and finger touch functionality while managing electromagnetic interference (EMI) and power consumption.
Innovation Solution
A touch display device and driving method that includes a touch sensor with touch electrodes and a driving circuit to output uplink signals with varying amplitudes and frequencies, and adjust pulse modulation signals based on touch type, to mitigate EMI and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the uplink signal amplitude is increased to improve pen touch detection accuracy, then the pen touch functionality is enhanced, but electromagnetic interference increases
Solution Approach 1:
The patent applies dynamics by making the uplink signal amplitude adjustable rather than fixed. The touch driving circuit dynamically changes the signal amplitude based on the detected touch type: using a first amplitude for finger touches and a second, larger amplitude for pen touches. This dynamic adjustment allows the system to optimize detection accuracy for different touch types while minimizing electromagnetic interference when high amplitude is not needed.
Solution Approach 2:
The patent implements parameter changes by modifying the amplitude parameter of the uplink signal based on touch type detection. The system detects whether a finger or pen is touching the display and accordingly changes the signal amplitude parameter - using a lower amplitude for finger touches to reduce EMI and a higher amplitude for pen touches to ensure accurate detection of the weaker pen signals.
2Reliability
If the uplink signal is continuously transmitted at high amplitude to ensure reliable pen touch detection, then detection reliability is improved, but power consumption increases
Solution Approach 1:
The system dynamically adjusts the uplink signal amplitude based on real-time touch detection results. When a pen touch is detected, the system switches to the second (higher) amplitude for reliable detection. When only finger touch or no touch is detected, it uses the first (lower) amplitude. This dynamic behavior ensures detection reliability when needed while reducing power consumption during normal operation.
Solution Approach 2:
The patent changes the amplitude parameter of the uplink signal based on operational conditions. By detecting touch type and accordingly switching between two amplitude levels, the system maintains reliable pen touch detection when required while significantly reducing power consumption during periods when pen touch is not active, thus resolving the contradiction between reliability and energy usage.
3Adaptability or versatility
If the touch driving circuit uses a fixed high amplitude signal to support both finger and pen touch, then both touch types can be detected, but electromagnetic interference increases and power consumption rises
Solution Approach 1:
The touch driving circuit dynamically adapts its signal amplitude based on the detected touch type. It starts with a first amplitude suitable for finger touch detection, and when pen touch is detected (through analysis of downlink signals), it switches to a second, higher amplitude for subsequent uplink signals. This dynamic adaptation allows the system to support both touch types effectively while minimizing electromagnetic interference by using the minimum necessary signal strength.
4Measurement precision
If the uplink signal amplitude is increased to compensate for weaker pen touch signals, then pen touch detection sensitivity is improved, but the contrast with finger touch signals decreases
Solution Approach 1:
The system dynamically adjusts the uplink signal amplitude based on touch type detection results. When finger touch is detected, it uses the first amplitude that provides good contrast for finger touch signals. When pen touch is detected, it switches to the second, higher amplitude to improve sensitivity for the weaker pen touch signals. This dynamic adjustment maintains optimal signal characteristics for each touch type while preserving the ability to distinguish between them.
Data Source
AI summary
A touch display device, a driving circuit, and a driving method according to embodiments of the disclosure can output an uplink signal having a first amplitude before receiving a downlink signal and output an uplink signal having a second amplitude higher than the first amplitude after receiving the downlink signal, thereby effectively mitigating the level of electromagnetic interference noise.