LCD Electrode Slits Prevent Short-Circuiting and Boost Transmissivity
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Solution Overview
Problem
In liquid crystal display devices, the overlap of pixel and counter electrodes leads to short-circuiting failures, reduced transmissivity due to large contact holes, and disturbed liquid crystal orientation, resulting in lower image quality and numerical aperture.
Innovation Solution
The design includes a planar counter electrode and a comb-shaped or slit-shaped pixel electrode with notches or slits, where the wiring layer is connected through a through hole in the insulation film, avoiding overlap and using a transparent electrode material to minimize defects and enhance transmissivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the counter electrode is formed over the whole area of the pixel region with strip-like pixel electrodes arranged in parallel, then the electrical connection is improved, but the overlapped area between counter electrode and pixel electrode increases causing short-circuiting failures
Solution Approach 1:
The patent extracts the problematic overlapping region by forming slits in the counter electrode that align with the pixel electrodes. This removes the counter electrode material from the regions where short-circuiting could occur through pinholes in the insulation film, while maintaining electrical connection through the through-holes that pass through the insulation film to contact the pixel electrodes.
2Reliability
If contact holes with large areas are formed to connect pixel electrode and thin film transistor, then the connection reliability is improved, but the numerical aperture and transmissivity are lowered
Solution Approach 1:
The patent changes the parameter of contact hole size by forming through-holes that extend through the insulation film to contact the pixel electrodes. The slits in the counter electrode allow these through-holes to be formed with minimal impact on transmissivity, as the slits reduce the overlapping area and thus the required contact hole area for reliable connection.
3Reliability
If counter electrode lines with large width are used to supply signal to counter electrodes, then the electrical resistivity is reduced, but the transmissivity is lowered
Solution Approach 1:
The patent transitions from a two-dimensional planar connection to a three-dimensional through-hole connection. The through-holes extend vertically through the insulation film, allowing electrical connection without requiring wide lateral paths. The slits in the counter electrode enable this vertical connection approach, reducing the need for wide counter electrode lines and thus improving transmissivity while maintaining low electrical resistivity.
4Reliability
If contact holes are formed to connect wiring layer and pixel electrode, then the electrical connection is established, but stepped portions are formed causing liquid crystal orientation disturbance
Solution Approach 1:
The patent extracts the counter electrode material from the regions around the through-holes by forming slits. This removal of counter electrode material eliminates the stepped portions that would otherwise be formed at the interfaces between contact holes and counter electrode, thereby preventing liquid crystal orientation disturbance while maintaining electrical connection through the through-holes.
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 prevents short-circuiting, reduces point defects, and improves image quality and numerical aperture by maintaining high transmissivity and minimizing disturbances in liquid crystal orientation.
Implementation Method 1
generates an electric field between the pixel electrode and the counter electrode
Implementation Method 2
disturbance of the liquid crystal orientation around peripheries of contact holes
Implementation Method 3
the numerical aperture, that is, the transmissivity of the liquid crystal display device
Data Source
AI summary
In a liquid crystal display device including a pair of substrates which face each other with a liquid crystal layer disposed therebetween, a plurality of pixel regions which are formed on one substrate, a planar counter electrode which is formed on each pixel region, and a comb-shaped or slit-shaped pixel electrode which is formed on each pixel region, the comb-shaped or slit-shaped pixel electrode being formed over the counter electrode by way of an insulation layer, a notch or a slit is formed in the counter electrode such that a wiring layer made of an opaque material which transmits a potential to the pixel electrode from a thin film transistor defines a region where the wiring layer is not overlapped relative to the counter electrode.