Touch System Orthogonal Drive Signals Simultaneous Detection
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Solution Overview
Problem
Conventional touch screen driving schemes are inefficient for larger panel sizes and higher resolutions, as they cannot complete driving and detection in time without causing detection loss.
Innovation Solution
A touch system that simultaneously drives and detects at least one pair of electrode lines using orthogonal drive signals and a receiver detection unit, which includes an IQ demodulator and analog-to-digital converter to estimate capacitances, and optionally employs a partial window function to attenuate noise without significantly increasing bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional sequential driving scheme is used, then device complexity is reduced, but driving speed and productivity deteriorate
Solution Approach 1:
The patent segments the driving task by dividing electrode lines into multiple groups that can be driven simultaneously. Instead of driving all electrode lines sequentially, the system divides them into independent groups that operate in parallel, thereby increasing driving speed without requiring complete redesign of the driving architecture.
Solution Approach 2:
The patent employs dynamic signal processing techniques including IQ demodulation and adaptive noise filtering that adjust processing parameters in real-time based on detected signals. This dynamic approach enables the system to handle multiple simultaneously driven electrode lines while maintaining signal integrity and reducing interference.
2Productivity
If more electrode lines are driven simultaneously, then productivity increases, but noise interference increases
Solution Approach 1:
The patent introduces an intermediary processing stage using IQ demodulation and digital signal processing between the simultaneous electrode driving and final detection. This intermediary layer separates and processes signals from different electrode groups, filtering out noise and interference before final capacitance calculation, thereby enabling high-productivity simultaneous driving with controlled noise levels.
Solution Approach 2:
The patent changes signal parameters by using orthogonal drive signals with specific frequency relationships and applying adaptive filtering parameters. By adjusting frequency separation and applying noise attenuation algorithms, the system can drive more electrode lines simultaneously while maintaining signal-to-noise ratio above acceptable thresholds.
3Measurement precision
If bandwidth is increased to improve detection accuracy, then measurement precision improves, but noise attenuation capability deteriorates
Solution Approach 1:
The patent implements feedback mechanisms where the detected sense signals are continuously processed and used to adjust driving parameters and filtering settings. The IQ demodulation provides feedback on signal quality, allowing the system to optimize the balance between bandwidth utilization and noise attenuation dynamically, maintaining measurement precision without excessive noise.
4Loss of time
If sequential driving is used, then noise is reduced, but detection time increases
Solution Approach 1:
The patent employs periodic orthogonal drive signals with carefully selected frequencies and phases. By using periodic actions that are mathematically orthogonal, the system can multiplex multiple electrode line driving operations in a periodic fashion, reducing total detection time while the periodic nature allows for effective noise filtering through synchronous detection techniques.
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
This approach significantly increases driving speed and reduces noise interference, enabling efficient operation on advanced touch screens with larger panels and higher resolutions.
Implementation Method 1
A sense signal is induced on the RX electrode line by capacitances disposed between the TX electrode lines and the RX electrode line
Implementation Method 2
The TX driving unit is configured to generate at least one pair of orthogonal drive signals, each pair having a specific frequency
Data Source
AI summary
In a touch system, a transmitter (TX) driving unit generates at least one pair of orthogonal drive signals, each pair having a specific frequency. At least one pair of TX electrode lines is simultaneously driven by the at least one pair of orthogonal drive signals, respectively. A sense signal is induced on a receiver (RX) electrode line by capacitances disposed between the TX electrode lines and the RX electrode line. An RX detection unit detects the sense signal to simultaneously result in two sense components that respectively estimate the capacitances associated with the TX electrode lines of the pair.