Gate Driver Re-driving for Touch Screen Display Line Dim
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Solution Overview
Problem
Touch screen LCD devices experience a 'line dim' phenomenon due to the voltage difference between display and touch sensing intervals, leading to image faults and decreased touch report rates.
Innovation Solution
A touch screen display device with a gate driver that groups gate lines into blocks, a data driver for sequential data line driving, a common voltage generator for applying common voltage, and an in-set signal controller for storing and supplying data signals, allowing for efficient touch position detection and image display without the line dim phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gate lines are sequentially driven in display and touch sensing intervals, then touch position detection is enabled, but voltage difference causes line dim phenomenon and image faults
Solution Approach 1:
The patent applies preliminary action by pre-driving the last gate line of each block during the display interval before the touch sensing interval begins. This ensures that the gate line is already activated and maintaining proper voltage levels before touch sensing operations start, preventing the voltage difference that causes line dim phenomenon. The gate driver stores the drive signal for the last gate line and re-applies it during touch sensing interval to maintain image quality while enabling accurate touch detection.
2Productivity
If touch sensing is performed between display intervals, then touch report rate is enhanced, but voltage variation causes line dim phenomenon
Solution Approach 1:
The patent implements feedback by monitoring the drive signal of the last gate line and using this information to control the timing and voltage levels during touch sensing operations. The gate driver circuit detects when the last gate line of a block is driven and uses this feedback to trigger the re-driving operation during the touch sensing interval, ensuring that voltage levels are maintained appropriately and preventing line dim phenomenon while maintaining high touch report rates.
3Productivity
If gate lines are grouped into blocks for sequential driving, then touch sensing efficiency is improved, but voltage difference between blocks causes image faults
Solution Approach 1:
The patent applies equipotentiality by ensuring that the last gate line of each block is maintained at the same voltage potential as it was during the display interval, even during the touch sensing interval. The gate driver circuit re-applies the stored drive signal to each block's last gate line during touch sensing, ensuring that all blocks maintain consistent voltage levels and preventing image faults or non-uniformity across the display while maintaining efficient block-based touch sensing operations.
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 prevents the line dim phenomenon by re-driving the last gate line with stored in-set signals, reducing voltage differences and maintaining image quality while enhancing touch report rates.
Implementation Method 1
The capacitive touch sensor recognizes a touch by sensing a variation of the capacitance which is generated by the movement of electric charges toward a touch point when a conductive material such as a part of a human body or a stylus pen touches it.
Implementation Method 2
The photo touch sensor senses a loss current of the photo transistor, which varies along the quantity of light being intercepted or reflected by a touch object, and recognizes a touch.
Data Source
AI summary
A touch screen display device is discussed. The device uses common electrodes, which are formed for display images, as touch electrodes. In a display interval, the common electrodes receive a common voltage and allow images to be displayed. In a touch sensing interval corresponding to a non-display interval of a single frame of plural frames, the common electrodes are driven as the touch electrodes and allow a touch position to be sensed. When the touch sensing interval is terminated, the data voltages which had been applied to the data lines before the touch sensing interval are re-applied to the data lines. As such, when a succeeding display interval starts after the touch sensing interval, the reduction of charging voltage in a pixel can be prevented or reduced. Therefore, a picture fault or an image fault can be prevented.