IPS LCD Common Electrode Wiring Removal Aperture Ratio
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Solution Overview
Problem
The existing IPS mode LCD devices have a low aperture ratio due to the need for common electrode wiring on the TFT substrate, which also leads to issues like spots, stains, and afterimages caused by charge accumulation from conductive materials on the color filter substrate.
Innovation Solution
The solution involves forming a second common electrode on the color filter substrate, which electrically connects to the first common electrode on the TFT substrate via conductive spacers or pillars, eliminating the need for common electrode wiring on the TFT substrate and shielding the color layer and black matrix layer from the electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If common electrode wiring is formed on the TFT substrate, then the LCD device can be driven properly, but the aperture ratio of the display area decreases
Solution Approach 1:
The patent moves the common electrode wiring from the TFT substrate (first substrate) to the color filter substrate (second substrate). By changing which substrate carries the wiring, the display area on the TFT substrate is maximized while the wiring is positioned on the opposing substrate where it does not obstruct the display aperture.
Solution Approach 2:
The patent introduces conductive spacers or conductive pillars as intermediary structures to electrically connect the common electrode wiring on the color filter substrate to the common electrode on the TFT substrate. These intermediaries enable electrical connectivity while maintaining the spatial separation that maximizes aperture ratio.
2Reliability
If conductive materials are formed on the color filter substrate, then the LCD device can be driven, but spots, stains and afterimages occur due to charge accumulation
Solution Approach 1:
The patent extracts the common electrode wiring from the TFT substrate and relocates it to the color filter substrate. This extraction removes the source of charge accumulation that causes spots and stains, as the wiring is now positioned on the substrate where it cannot accumulate charge in the same harmful manner.
Solution Approach 2:
The patent converts the potential harm of having conductive materials on the color filter substrate into a benefit by using conductive spacers or pillars to create controlled electrical connections. These intermediaries provide necessary electrical connectivity while preventing uncontrolled charge accumulation that causes defects.
3Area of stationary object
If common electrode wiring is removed from the TFT substrate, then the aperture ratio increases, but electrical connection to the common electrode becomes difficult
Solution Approach 1:
The patent introduces conductive spacers or conductive pillars as intermediary structures to bridge the electrical gap between the common electrode wiring on the color filter substrate and the common electrode on the TFT substrate. These intermediaries simplify the manufacturing process by providing clear electrical connection paths.
Solution Approach 2:
The patent replaces complex wire bonding or trace routing mechanisms with simpler conductive spacers or pillars that provide direct electrical connection. This substitution simplifies the manufacturing process and improves reliability by eliminating the need for delicate wire connections across the substrate gap.
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 configuration increases the aperture ratio of the display area by removing the common electrode wiring from the TFT substrate, reducing the occurrence of spots, stains, and afterimages, while allowing for a reduced driving voltage due to effective electric field application.
Implementation Method 1
a liquid crystal is driven by a transverse electric field parallel to the both substrates. In this IPS mode, when an electric field is applied to a liquid crystal, a liquid crystal molecule rotates in parallel with the substrate
Implementation Method 2
a conduction part for electrically connecting the second common electrode and the first common electrode mutually and transmitting the common electric potential to the first common electrode is formed near each display pixel or near a predetermined display pixel
Data Source
AI summary
A liquid crystal display device of the present invention includes a TFT substrate having a substrate and a display pixel arranged in a matrix form on the substrate, a counter substrate opposed to the TFT substrate and being stuck therewith and a liquid crystal enclosed between the TFT substrate and the counter substrate, the pixel electrode and the first common electrode are arranged so that an electric field along a principal plane of the TFT substrate can be applied to the liquid crystal, a second common electrode for inputting a common electric potential is formed on the counter substrate, the second common electrode is opposed to the first common electrode, and a conduction part for electrically connecting the second common electrode and the first common electrode mutually and transmitting the common electric potential to the first common electrode is formed near each display pixel or near a predetermined display pixel.