Touchscreen Sub-Pixel Coordinate Scaling for Higher Touch Accuracy
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Solution Overview
Problem
Conventional capacitive touchscreens are limited in touch coordinate resolution to whole pixel units, unable to detect locations between intersections of drive and sense lines, restricting accuracy in applications like augmented reality and gaming.
Innovation Solution
A method involving a touchscreen controller that scales up touch coordinates by overwriting a reserved portion of the touch event protocol with additional information, allowing the application processor to convert these scaled coordinates into floating-point values for increased resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capacitive touchscreen coordinates are used, then the device structure remains simple, but the touch coordinate resolution is limited to whole pixel values
Solution Approach 1:
The patent introduces a new dimension of precision by adding sub-pixel coordinate information (tenths of a pixel) to the traditional whole pixel coordinate system. This is achieved by overwriting the reserved byte in the touch event protocol to store additional coordinate precision data, thereby transforming the coordinate representation from discrete pixel units to continuous sub-pixel values without fundamentally changing the touchscreen hardware structure.
Solution Approach 2:
The patent changes the parameter representation of touch coordinates from integer pixel values to floating-point sub-pixel values. By modifying the coordinate data format to include tenths of a pixel precision and using floating-point arithmetic for coordinate calculations, the system achieves higher measurement precision while managing complexity through software-based parameter transformation rather than hardware modification.
2Measurement precision
If touchscreen resolution is increased to improve touch accuracy, then the manufacturing cost and device complexity increase, but the basic pixel grid structure remains the same
Solution Approach 1:
Instead of physically increasing the touchscreen pixel density, the patent changes the parameter representation of coordinates to include sub-pixel precision (tenths of a pixel). This software-based approach to enhancing accuracy avoids the need for manufacturing higher-resolution physical touchsensor arrays, thereby maintaining ease of manufacture while achieving improved touch accuracy through coordinate scaling and floating-point representation.
Solution Approach 2:
The patent creates a virtual high-resolution coordinate system by scaling up the existing physical pixel coordinates. Rather than building a new physical sensor array with higher density, the system copies and transforms the coordinate data to represent positions with sub-pixel precision, effectively creating a virtual representation that exceeds the physical hardware capabilities without requiring physical hardware changes.
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.