In-Cell Touch LCD Crosstalk Compensation via DTX Weighting
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Solution Overview
Problem
In in-cell touch LCD devices, display touch crosstalk occurs due to the structural integration of touch sensors within the liquid crystal panel, affecting touch sensitivity and accuracy by causing noise from capacitance differences between pixels displaying black and white, leading to false touch detection even without user input.
Innovation Solution
A timing controller alternately drives display and touch modes within a frame period, using a touch sensing unit that calculates a DTX compensation value by multiplying a DTX weight value with the maximum DTX amplitude of touch sensing blocks, derived from normalization curves based on grayscale values, to correct for display touch crosstalk and enhance touch sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If touch sensors are built in the liquid crystal panel, then the device structure is integrated and slimmed, but display touch crosstalk occurs affecting touch sensing accuracy
Solution Approach 1:
The patent applies preliminary action by measuring and storing DTX amplitude values for each touch sensing block during display mode operation before touch sensing occurs. These pre-measured values are used to calculate compensation values that are applied during subsequent touch sensing mode, eliminating the need for complex real-time adjustments and improving touch sensing accuracy while maintaining integrated structure.
Solution Approach 2:
The patent implements feedback by continuously monitoring display mode operation to measure DTX amplitude changes, using these measurements to calculate compensation values, and then applying these compensation values during touch sensing mode. This closed-loop feedback mechanism ensures that display touch crosstalk is continuously compensated for, resolving the accuracy issue while maintaining structural integration.
2Ease of manufacture
If common electrodes are used as touch electrodes, then manufacturing is simplified, but display and touch sensing functions interfere with each other
Solution Approach 1:
The patent applies periodic action by alternating between display mode and touch sensing mode in a time-division manner. During display mode, common electrodes function as display electrodes; during touch sensing mode, the same electrodes function as touch electrodes. This periodic switching allows the common electrodes to serve dual purposes without functional interference, maintaining manufacturing simplicity while ensuring functional independence.
Solution Approach 2:
The patent uses preliminary action by measuring DTX amplitude values during display mode before touch sensing occurs. These pre-measured values enable the system to compensate for display touch crosstalk during subsequent touch sensing mode, allowing the common electrodes to function reliably as touch electrodes without interference from display operations, thus maintaining both manufacturing simplicity and functional independence.
3Stability of the object's composition
If capacitance difference between pixels is maintained, then display function is preserved, but touch sensitivity is affected by noise
Solution Approach 1:
The patent implements feedback by continuously monitoring display mode operation to measure DTX amplitude changes caused by capacitance differences between pixels. These measured values are used to calculate compensation values that are applied during touch sensing mode to eliminate noise while preserving the display function's stability. The feedback mechanism ensures that harmful noise is continuously compensated without affecting display performance.
Solution Approach 2:
The patent converts the harmful display touch crosstalk noise into a beneficial measurement by measuring DTX amplitude values during display mode and using these values to calculate compensation values. This transforms the previously harmful noise into useful information that enables accurate touch sensing, effectively converting the harmful factor into a benefit while maintaining display function stability.
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 noise in touch signals, improving touch sensing accuracy and rate by compensating for display touch crosstalk, ensuring reliable user input detection without false positives.
Implementation Method 1
when a capacitance is changed in a touch sensing block touched by a user's finger, a touch sensing electrode senses the changed capacitance
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
Disclosed is a display device. The display device includes a timing controller and a touch sensing unit. The timing controller temporally divides one frame period and drives 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. The touch sensing unit detects the user's touch with a DTX compensation value calculated by multiplying a DTX weight value and a maximum DTX amplitude of a touch sensing block which is obtained when a maximum grayscale value is applied to a plurality of pixels corresponding to the touch sensing block, in the touch mode. The DTX weight value is calculated by substituting an average value of grayscale values applied to the plurality of pixels corresponding to the touch sensing block into a normalization curve.