Touch Screen Driver Modulates Rx Sampling Clocks for RC Delay Compensation
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Solution Overview
Problem
Mutual capacitive touch screens face challenges in accurately detecting touch signals due to RC delay deviations between channels, leading to sampling deviations and reduced signal-to-noise ratios.
Innovation Solution
A touch screen driver that modulates Rx sampling clocks based on RC delay deviations between channels, allowing for differential control of sampling times, thereby improving signal detection and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If simultaneous sampling is applied to all Rx channels using the same sampling clocks, then the sampling process is simple and synchronized, but sampling deviation occurs due to different RC delays in each channel
Solution Approach 1:
The patent applies different sampling timing characteristics to different Rx channels based on their individual RC delay characteristics. Each channel is sampled at its optimal time point rather than using a uniform sampling scheme, thereby compensating for channel-specific delays and improving measurement precision while maintaining operational feasibility.
2Device complexity
If the same sampling time is used for all Rx channels, then the sampling control is simple, but the signal-to-noise ratio is reduced due to sampling deviation
Solution Approach 1:
The patent changes the sampling time parameter for each Rx channel based on its RC delay characteristics. By adjusting the sampling time parameter individually for each channel, the system optimizes the signal-to-noise ratio for each channel while managing the overall control complexity through systematic parameter adjustment.
3Measurement precision
If different sampling times are applied to compensate for RC delay deviations, then touch signal detection accuracy is improved, but the sampling control becomes more complex
Solution Approach 1:
The patent performs preliminary measurement of RC delay characteristics for each Rx channel before the actual sampling process. Based on these pre-measured characteristics, the optimal sampling time points are determined in advance. This preliminary action allows the system to compensate for RC delay deviations and improve measurement precision while managing control complexity through pre-characterization.
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 enables accurate detection of touch signals and enhances signal-to-noise ratios, improving touch resolution and accuracy across the entire touch screen area.
Implementation Method 1
Each of the sensor nodes has a mutual capacitance. A touch screen driver senses changes in the voltages charged to the sensor nodes
Implementation Method 2
an Rx driving circuit samples a small change in the voltages of the sensor nodes in synchronization with the driving pulse and performs the analog-to-digital conversion
Data Source
AI summary
A touch screen driver includes a touch screen including Tx channels, Rx channels crossing the Tx channels, and sensor nodes formed at crossings of the Tx channels and the Rx channels, a Tx driving circuit supplying a driving pulse to the Tx channels, an Rx driving circuit which samples voltages of the sensor nodes supplied through the Rx channels in response to Rx sampling clocks and converts the sampled voltages into digital data, and a touch controller which modulates the Rx sampling clocks based on an RC delay deviation between the Rx channels, supplies the modulated Rx sampling clocks to the Rx driving circuit, differently controls sampling times of the Rx channels, and analyzes the digital data using a previously determined touch recognition algorithm.