In-Cell Touch Crosstalk Compensation in Liquid Crystal Displays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In-cell touch type liquid crystal display devices face issues with display touch crosstalk, where capacitance differences between pixels for displaying black and white affect touch sensing accuracy and stability, leading to noise and deteriorated touch performance.
Innovation Solution
A display device with a timing controller that alternately drives displaying and touch sensing modes using a time division method, incorporating a touch sensor that calculates compensation values based on grayscale averages to compensate for display touch crosstalk, thereby improving touch sensitivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a touch sensor is provided inside the liquid crystal panel (in-cell touch type), then the device achieves slimness and integration, but display touch crosstalk occurs due to capacitance differences between pixels, deteriorating touch sensing accuracy
Solution Approach 1:
The patent applies preliminary action by performing DTX compensation before touch sensing. The timing controller calculates compensation values based on display data and subtracts these compensation values from raw touch sensing data, thereby eliminating display-induced capacitance differences before they interfere with touch detection accuracy
Solution Approach 2:
The patent introduces an intermediary compensation mechanism between the display system and touch sensing system. The timing controller acts as an intermediary that processes both display and touch data, calculating and applying DTX compensation values to isolate the touch sensing signal from display-induced noise
2Ease of manufacture
If the touch sensor shares the liquid crystal panel structure with display pixels, then manufacturing is simplified, but the displaying driving mode and touch sensing driving mode mutually affect each other
Solution Approach 1:
The patent applies periodic action by alternately switching between display driving mode and touch sensing driving mode in time-division multiplexing. The timing controller manages periodic transitions between these modes, enabling the shared liquid crystal panel structure to serve both functions at different time intervals without mutual interference
Solution Approach 2:
The patent changes operational parameters by adjusting voltage levels and timing sequences during mode transitions. The timing controller modifies driving voltages and sensing parameters dynamically based on the current mode (display or touch sensing), ensuring stable operation despite mode switching in the integrated structure
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
The solution effectively compensates for display touch crosstalk, enhancing touch sensitivity and stability by reducing noise in touch signals, leading to improved user input accuracy on liquid crystal display devices.
Implementation Method 1
If there is a user's touch during a touch sensing period (non-display period), a capacitance change occurs in a touch sensing block with the user's touch, and a touch sensing electrode senses the capacitance change
Implementation Method 2
an alignment of liquid crystal in the pixel for displaying black (black) is different from an alignment of liquid crystal in the pixel for displaying white (white), whereby a capacitance difference (Cm_w−Cm_b) of a liquid crystal layer occurs
Data Source
AI summary
Disclosed is a display device capable of improving touch sensitivity by removing noise from a user's touch signal through compensation of display touch crosstalk, and a touch sensing method thereof, wherein the display device may include a timing controller for driving one frame by a time division method to alternately perform a displaying driving mode and a touch sensing mode; and a touch sensor for determining a DTX compensation block including at least one touch sensing block corresponding to a unit for sensing a user's touch; calculating a compensation representative value and a sensing block average value; and sensing a user's touch by compensating for touch data in accordance with a difference between the compensation representative value and the sensing block average value.