Touch Panel Driving Method Using Differential Pairs and Hadamard Codes
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Solution Overview
Problem
Existing touch panel driving methods face challenges in reducing the dynamic range of signals received by sensing lines and improving the signal-to-noise ratio, leading to increased complexity and size of the analog front-end, as well as susceptibility to quantization and circuit noise due to higher voltage levels or multiplexing techniques.
Innovation Solution
The method involves pairing neighboring driving lines to form pairs with opposite phases, shuffling their positions, and generating Hadamard codes to simultaneously drive the lines, reducing the dynamic range and improving signal quality by minimizing noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the voltage level of the pulse sequence is raised to increase signal intensity, then the signal-to-noise ratio is improved, but the dynamic range of signals received by the sensing unit increases, leading to increased analog front-end complexity and size
Solution Approach 1:
The patent changes the driving method from single-ended to differential mode, where adjacent driving lines are driven with opposite-phase signals. This parameter change allows the system to achieve high signal-to-noise ratio through differential sensing while keeping the voltage levels moderate, thus avoiding the need for complex high-voltage analog front-end circuits
Solution Approach 2:
The patent uses complementary copying by driving adjacent lines with inverted signals. The sensing unit measures the differential signal between adjacent lines, effectively copying the touch interaction pattern while rejecting common-mode noise and reducing the dynamic range requirement
2Duration of action of moving object
If multiplexing techniques are used to extend sensing time, then the sensing time is elongated, but the signal intensity during data conversion is reduced, making the system susceptible to quantization noise and circuit noise
Solution Approach 1:
The patent enables continuous sensing by simultaneously driving multiple driving lines in differential mode. Instead of sequentially multiplexing lines which reduces signal intensity during conversion, the system maintains continuous differential signaling across all lines, preserving signal intensity while achieving extended sensing coverage
Solution Approach 2:
The patent merges the sensing operations of multiple driving lines by using differential measurement between adjacent lines. This combining approach allows the system to process multiple lines simultaneously without reducing individual signal intensity, as the differential measurement amplifies the useful signal while rejecting common noise
3Duration of action of moving object
If multiplexing techniques are used to extend sensing time, then the sensing time is elongated, but the size and complexity of the analog front-end increases
Solution Approach 1:
The patent changes the operational mode from sequential multiplexing to simultaneous differential operation. This parameter change allows the system to achieve extended sensing time through parallel processing of multiple line pairs while keeping the analog front-end size compact, as each sensing channel processes differential signals independently
Data Source
AI summary
Disclosed herein is a method of driving a touch panel having driving lines, sensing lines, and node capacitors between neighboring driving lines and sensing lines. The method includes pairing two neighboring driving lines, setting the pairs such that each of the pairs is driven using driving signals having an opposite phase, shuffling positions of the pairs so that at least one set of neighboring pairs includes different driving lines, classifying or combining at least two shuffled pairs into one group, generating Hadamard codes based on the pairs in each group, and simultaneously driving the driving lines in each of the generated Hadamard codes.