Touch Screen Scan Speed Optimization Using Orthogonal PN Codes
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Solution Overview
Problem
As the size of touch screens increases, the number of touch electrodes grows, leading to slower scan speeds for detecting external conductive objects, which hampers the frequency and efficiency of reporting touch events.
Innovation Solution
The implementation of a touch sensitive processing method using orthogonal pseudo random number (PN) codes, where multiple first electrodes transmit modulated signals and second electrodes sense information to generate one-dimensional arrays, calculating sums to determine if they fall within a specific range, thereby accelerating detection and reducing computational resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the number of touch electrodes is increased to cover larger touch screen area, then the coverage area is improved, but the scan speed decreases
Solution Approach 1:
The touch screen is divided into multiple blocks, with each block containing a subset of first electrodes and second electrodes. The scanning process is segmented into multiple phases, where each phase scans one block at a time. This segmentation allows the system to maintain a large overall coverage area while reducing the scanning time for each individual block, thereby improving the overall scan speed.
Solution Approach 2:
The patent employs periodic scanning of blocks in a systematic sequence. After completing the scanning of one block, the system immediately transitions to scanning the next block in the predetermined sequence. This periodic action ensures continuous scanning coverage across the entire touch screen without idle time, maintaining high scan speed while covering large areas.
2Measurement precision
If the number of touch electrodes is increased to maintain high resolution, then the measurement precision is improved, but the computational resources required increase
Solution Approach 1:
The computational process is segmented by processing blocks independently. Instead of processing the entire touch screen at once, the system calculates capacitance changes for each block separately. This segmentation reduces the computational load for each processing cycle while maintaining the precision needed for accurate touch event detection across the entire screen.
Solution Approach 2:
The patent extracts and processes only the necessary information from each block during scanning. By focusing computational resources on calculating capacitance changes within each specific block and only when needed, the system reduces overall computational resource requirements while preserving measurement precision for touch event detection.
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 enhances the speed and accuracy of detecting touch events while minimizing computational waste, leveraging the balance property of PN codes for improved interference resistance and faster event detection.
Implementation Method 1
transmitting driving signals modulated by the N modified PN codes via N of the multiple first electrodes
Implementation Method 2
sensing in a period of M symbols via the second electrodes to generate M one-dimensional sensing information arrays
Data Source
AI summary
A touch sensitive processing method, comprising: generating modified codes of N orthogonal pseudo random number (PN) codes, each of PN code has M symbols, where M and N are positive integers larger than 1; transmitting driving signals modulated by the N modified codes via N first electrodes, respectively, and sensing via multiple second electrodes in a M symbols period to generate M one-dimensional sensing information arrays; calculating sums of corresponding elements of the M one-dimensional sensing information arrays corresponding to each of the second electrodes, respectively; determining whether each of the sums is in a range; and recording the M one-dimensional sensing information arrays and their corresponding N first electrodes and N PN codes in response to that at least one of the sums is determined out of the range.