Touchscreen Coordinate Scaling for Sub-Pixel Touch Resolution
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Solution Overview
Problem
Conventional touchscreens have limited resolution for touch coordinates, which are restricted to whole pixel units and cannot accurately represent locations between intersections of drive lines and sense lines, limiting their precision.
Innovation Solution
A method and device configuration that scales up touch coordinates by overwriting a reserved portion of the touch event protocol with additional information, allowing the touchscreen controller to report coordinates with increased resolution to the application processor, enabling conversion into floating-point values for higher precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capacitive touchscreen coordinates are used, then the system is simple and compatible with standard protocols, but the touch coordinate resolution is limited to whole pixel values
Solution Approach 1:
The patent adds an additional dimension of precision by utilizing a reserved byte in the touch event protocol to store extra coordinate information. This transforms the coordinate representation from integer pixel values to floating-point values with sub-pixel precision, effectively adding a dimensional layer of accuracy without changing the fundamental protocol structure
Solution Approach 2:
The patent changes the parameter representation from discrete integer coordinates to continuous floating-point coordinates by using the reserved byte to store additional precision information. This parameter transformation enables sub-pixel resolution while maintaining compatibility with the existing touch event protocol framework
2Measurement precision
If the touchscreen controller reports only standard coordinates, then the data transmission is efficient and simple, but the application processor cannot achieve higher precision touch detection
Solution Approach 1:
The touchscreen controller performs preliminary scaling of the coordinates and packs the high-precision floating-point information into the reserved byte before transmission. This preliminary action ensures that the precision information is preserved and transmitted efficiently without requiring additional communication overhead or post-processing calculations at the application processor
Solution Approach 2:
The reserved byte in the touch event protocol serves as an intermediary carrier that transports the additional coordinate precision information from the touchscreen controller to the application processor. This intermediary mechanism enables high-precision touch detection without disrupting the existing protocol structure or requiring fundamental changes to the communication framework
Data Source
AI summary
A method for operating an electronic device includes detecting, by a touchscreen controller, a touch point on a touchscreen; determining, by the touchscreen controller, coordinates of the touch point; scaling, by the touchscreen controller, up the coordinates of the touch point to obtain scaled up coordinates by overwriting a reserved portion of a touch event protocol with additional information corresponding to the coordinates of the touch point; reporting, by the touchscreen controller, the scaled up coordinates of the touch point to an application processor; and determining, by the application processor, the coordinates of the touch point with an increased resolution by converting the scaled up coordinates into a floating point value.