In-Cell Touch Panel Counter Electrode Segmentation
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Solution Overview
Problem
In in-cell liquid crystal display devices with integrated touch panels, noise from gate scan interferes with scanning signals due to parasitic capacitance, leading to reduced detection sensitivity and variability in touch detection across different panels.
Innovation Solution
The solution involves dividing the counter electrode into blocks, which are shared among pixels and used as both display and touch panel scanning electrodes, with a driver circuit that adjusts the timing and amplitude of the touch panel scanning voltage to minimize noise interference and ensure consistent sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the counter electrode is used as scanning electrode for touch panel, then the device complexity is reduced, but noise from gate scan interferes with scanning signal due to parasitic capacitance, degrading detection sensitivity
Solution Approach 1:
The counter electrode is divided into multiple blocks along the vertical direction, with each block serving as scanning electrode for specific detection lines. This segmentation reduces parasitic capacitance interference from gate scan noise by isolating the scanning regions, thereby maintaining detection sensitivity while preserving the integrated in-cell structure.
Solution Approach 2:
Different blocks of the counter electrode are assigned different scanning voltage characteristics tailored to their specific detection line requirements. By optimizing the scanning voltage amplitude and timing for each block locally, the patent minimizes noise interference while maximizing detection sensitivity in each region.
2Adaptability or versatility
If common voltage is different for each liquid crystal display panel, then the touch panel scanning voltage amplitude varies across panels, but this causes uneven touch detection sensitivity
Solution Approach 1:
The patent implements dynamic adjustment of touch panel scanning voltage based on the actual common voltage of each liquid crystal display panel. The driver circuit measures or receives the common voltage value and automatically adjusts the scanning voltage amplitude in real-time, ensuring consistent detection sensitivity across panels with different common voltage characteristics.
Solution Approach 2:
The patent changes the scanning voltage parameter (amplitude) according to the common voltage value of each panel. By making the scanning voltage adaptive to panel-specific electrical characteristics, the system maintains uniform detection sensitivity across different panels despite variations in common voltage.
3Adaptability or versatility
If touch panel scanning voltage is applied to counter electrode, then in-cell touch panel function is achieved, but gate scan noise interferes with scanning signal
Solution Approach 1:
The counter electrode is segmented into multiple blocks, each handling scanning for specific detection lines. This segmentation isolates the scanning operations spatially, reducing the impact of gate scan noise from other regions and enabling the integrated in-cell touch panel function with reduced noise interference.
Solution Approach 2:
The patent employs periodic scanning voltage application with optimized timing to synchronize touch detection operations with the display scanning cycles. By carefully timing the scanning voltage pulses, the system minimizes overlap with gate scan operations, reducing noise interference while maintaining the integrated touch panel functionality.
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 prevents degradation of detection sensitivity and reduces variability in touch detection sensitivity across liquid crystal display devices, enhancing the reliability and performance of in-cell touch panels.
Implementation Method 1
a capacitance type touch panel that detects a change in the capacitance of a touched portion
Implementation Method 2
noise of gate scan interferes with a scanning signal (so-called 'pulse voltage') due to a parasitic capacitance between the gate lines for display and the scanning electrode (so-called 'counter electrode')
Data Source
AI summary
In a liquid crystal display device with a touch panel function, a second substrate has detection electrodes of a touch panel, each pixel has a pixel electrode and a counter electrode, the counter electrode is divided into a plurality of blocks, and the counter electrodes of the respective divided blocks are shared to the respective pixels of a plurality of display lines side by side, the counter electrodes of the respective divided blocks is also used as scanning electrodes of the touch panel, and a driver circuit is provided to apply a counter voltage and a touch panel scanning voltage to the counter electrodes of the respective divided blocks, and the driver circuit can adjust a supply start timing of the touch panel scanning voltage to be applied to the counter electrodes of the respective divided blocks.