Display Panel Segmentation for In-Cell Touch Noise Cancellation
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Solution Overview
Problem
The in-cell touch sensor scheme in display devices experiences reduced Signal to Noise Ratio (SNR) due to low power voltage ELVSS affecting touch sensing, leading to image quality deterioration when touch operations are isolated from display operations.
Innovation Solution
A display device is divided into two areas, with separate source driving circuits and a timing controller that applies inverted image data to one area during display time to cancel noise components, allowing simultaneous display and touch operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If touch operation is isolated from display operation during vertical blank period, then touch sensing accuracy is improved, but image quality deteriorates due to FOS issue
Solution Approach 1:
The display panel is divided into first and second areas, with the first area displaying normal image data and the second area displaying inverted image data. This segmentation allows different regions to serve different functions: the first area maintains normal display quality while the second area generates compensating noise signals for touch sensing operations.
Solution Approach 2:
Inverted image data is applied to the second area of the display panel. This inversion creates noise components that are opposite in polarity to the noise generated during normal display operation, enabling noise cancellation through differential measurement in touch sensing.
2Productivity
If display operation and touch operation occur in the same frame, then productivity is improved, but touch SNR is reduced due to ELVSS coupling
Solution Approach 1:
The inverted image data in the second area acts as an intermediary that generates compensating noise signals. These signals serve as a reference for differential measurement, allowing touch sensing to proceed simultaneously with display operation while maintaining adequate SNR through noise cancellation.
3Measurement precision
If noise reduction technology is applied to improve touch SNR, then touch sensing accuracy is improved, but device complexity increases
Solution Approach 1:
The display function and touch sensing function are merged into the same frame period. By displaying inverted image data in the second area, the patent combines noise generation for touch sensing with the display function itself, eliminating the need for separate noise reduction hardware or temporal separation of operations.
Data Source
AI summary
A display device and a driving method thereof may be capable of compensating for noise caused by image data with inverted image data to cancel a noise component. The device includes a display panel divided into a first area and a second area; a first source driving circuit and a second source driving circuit for providing a source signal to the first area and the second area, respectively; a gate driving circuit for providing a scan signal; a touch driving circuit for applying a touch driving signal and sensing a touch signal; and a timing controller. The timing controller controls corresponding circuits to display first image data on the first area during a first display time, and to provide a source signal corresponding to first inverted data obtained by inverting the first image data to the second area during the first display time.