In-Cell Touch LCD Crosstalk Compensation via Temporal Segmentation
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Solution Overview
Problem
In-cell touch LCD devices experience display touch crosstalk, where the display function affects the touch sensing function, leading to reduced accuracy and stability due to capacitance differences between pixels displaying black and white, causing false touch detection.
Innovation Solution
A display device with a timing controller that alternately drives display and touch modes within a frame period, using a touch sensing unit to generate a display compensation value based on differential display data to correct touch raw data errors between adjacent touch sensing blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If touch sensors are built in the liquid crystal panel, then the device can be slimmed down, but display touch crosstalk occurs reducing touch sensing accuracy
Solution Approach 1:
The patent segments the frame period into distinct display modes and touch modes, allowing separate optimization of each function. By dividing the operation into temporal segments, the system can apply different driving conditions for display and touch sensing, reducing crosstalk while maintaining the built-in sensor structure.
Solution Approach 2:
The patent changes driving parameters dynamically based on the mode (display or touch). By adjusting voltage levels, timing, and signal characteristics according to the current mode, the system reduces interference between display and touch functions while maintaining the integrated structure.
2Ease of operation
If display and touch sensing are temporally divided and driven, then touch sensing can be performed, but display touch crosstalk still occurs due to capacitance differences between pixels
Solution Approach 1:
The patent performs preliminary compensation by calculating compensation values based on display data before actual touch sensing. The compensation values are prepared in advance to counteract the expected crosstalk effects, allowing accurate touch detection despite the temporal division limitation.
Solution Approach 2:
The patent implements feedback by using display data to generate compensation values that are applied to touch sensing results. The system continuously monitors display conditions and adjusts touch sensing compensation accordingly, creating a closed-loop system that reduces crosstalk effects.
3Device complexity
If common electrodes are used for both display and touch sensing, then device complexity is reduced, but display touch crosstalk occurs affecting touch detection accuracy
Solution Approach 1:
The patent makes the common electrodes universal by enabling them to serve both display and touch sensing functions through mode switching. The same physical electrodes are used for different purposes at different times, reducing device complexity while maintaining functionality through intelligent control.
Solution Approach 2:
The patent changes the operational parameters of the common electrodes based on the mode. During display mode, electrodes operate for image rendering; during touch mode, they operate for capacitance sensing. This parameter switching enables multi-functionality while reducing crosstalk through appropriate driving conditions.
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 effectively reduces display touch crosstalk, enhancing touch sensing accuracy and stability by compensating for errors in touch data, thereby improving the touch sensing rate and accuracy.
Implementation Method 1
a touch driving signal is applied to the touch driving electrodes 10 (TX), and the touch sensing electrodes 20 (RX) sense a capacitance change
Implementation Method 2
a pixel 'Black' displaying black and a pixel 'White' displaying white differ in alignment of liquid crystal, and thus, a difference between capacitances of a liquid crystal layer occurs
Data Source
AI summary
Provided are a display device and a touch sensing method of a display device. The display device includes a timing controller temporally dividing one frame period and driving a display panel such that a display mode for displaying an image in the display panel and a touch mode for sensing a user's touch are alternately driven, and a touch sensing unit detecting the user's touch with a touch raw data difference between adjacent touch sensing blocks in the touch mode. In the display mode, the touch sensing unit generates a display compensation value for compensating for an error of the touch raw data due to a differential of display data applied to the adjacent touch sensing blocks to detect the user's touch.