Counter Electrode Selector Circuit for In-Cell Touch Panel Frame Reduction
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Solution Overview
Problem
In liquid crystal display devices with built-in touch panels, the increase in panel size leads to a deterioration in image quality due to parasitic capacitance, resulting in wider frames and a larger display area, which is undesirable for in-cell type touch panels.
Innovation Solution
The implementation of a counter electrode selector circuit that divides the counter electrodes into blocks, allowing for common voltage and touch panel scanning voltage application, reducing the number of wirings and frame width by using address decoder circuits and selector circuits to selectively connect and disconnect counter electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the panel size is increased, then the display area is enlarged, but the frame width increases due to more wirings required for divided counter electrodes
Solution Approach 1:
The counter electrode is divided into multiple blocks (first counter electrode block and second counter electrode block) that can be independently controlled. This segmentation allows selective application of common voltage or touch panel scanning voltage to different blocks, reducing the number of wirings needed and thereby reducing frame width while maintaining large display area.
Solution Approach 2:
The divided counter electrode blocks serve dual functions: they act as common electrodes for liquid crystal display operation and as scanning electrodes for touch panel operation. This multi-functionality eliminates the need for separate electrode structures, reducing wiring requirements and frame width.
2Reliability
If the number of divided counter electrodes is increased, then the wiring resistance decreases, but the frame width increases proportionally
Solution Approach 1:
The counter electrode is divided into a manageable number of blocks (first and second blocks) that can be independently addressed. This segmentation optimizes the balance between reducing wiring resistance through division and minimizing frame width by avoiding excessive division that would require more wirings.
Solution Approach 2:
The counter electrode blocks are dynamically switched between common voltage mode and touch panel scanning voltage mode based on operational requirements. This dynamic control allows the system to optimize performance for different functions without requiring additional permanent wiring infrastructure.
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 solution reduces the frame area of liquid crystal display devices even when the panel size increases, maintaining image quality by minimizing the width of the right and left frames and enhancing touch panel sensitivity.
Implementation Method 1
there is a need to decrease a wiring resistance between each of the divided counter electrodes and a driver IC
Implementation Method 2
allowing for common voltage and touch panel scanning voltage application, reducing the number of wirings and frame width
Data Source
AI summary
A second substrate has detection electrodes of a touch panel, each of pixels has a pixel electrode and a counter electrode, the counter electrode is divided into a plurality of blocks, the counter electrodes of the respective divided blocks are commonly provided for the respective pixels of the plurality of display lines in series, and the counter electrodes also serve as scanning electrodes of the touch panel, and a counter electrode selector circuit that selects the counter electrodes. The counter electrode selector circuit includes an address decoder circuit that selects the counter electrodes of the respective blocks for a given period, and a selector circuit that applies a touch panel scanning voltage to the counter electrode of the block selected by the address decoder circuit, and applies a counter voltage to the counter electrodes of the blocks not selected by the address decoder circuit.