LCD Shield Electrode Layering for Signal Delay and Aperture Ratio
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Solution Overview
Problem
Conventional lateral electric field type liquid crystal display apparatuses face issues with signal delay, crosstalk, and decreased aperture ratio due to capacitance variations between signal wirings and shield electrodes, leading to potential variations that affect image quality and luminance.
Innovation Solution
A liquid crystal display apparatus with a first electric field shield electrode set to common potential, electrically separated from signal and common potential wiring, and a second electric field shield electrode superposed on signal wiring through an insulation film, reducing capacitance and allowing independent voltage supply paths, thereby minimizing potential variations and increasing aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the lower shield COM electrode is formed in the same layer as the scanning wiring with only a thin gate insulation film, then the device complexity is reduced, but the capacitance between signal wiring and lower shield COM electrode increases causing signal delay and potential variation
Solution Approach 1:
The patent introduces a new layer dimension by forming the lower shield COM electrode in a different layer than the scanning wiring, separated by an insulation film. This vertical layering approach reduces the horizontal capacitance coupling between signal wiring and shield electrode while maintaining the shielding function, thereby reducing signal delay without significantly increasing device complexity.
2Ease of manufacture
If the lower shield COM electrode is formed in the same layer as the scanning wiring, then the manufacturing process is simplified, but the aperture ratio decreases due to potential contact or superposition requirements
Solution Approach 1:
By moving the lower shield COM electrode to a different layer separated by an insulation film, the patent eliminates the need for horizontal spacing or complex contact hole structures that would reduce aperture ratio. The vertical separation allows the electrode to extend closer to the signal wiring without risk of contact, maintaining manufacturing simplicity while preserving pixel aperture area.
3Device complexity
If the upper shield COM electrode and counter electrode are electrically connected, then the device complexity is reduced, but the potential variation affects image quality due to capacitance coupling with signal wiring
Solution Approach 1:
The patent segments the electrical connections by introducing a contact hole structure that selectively connects the upper shield COM electrode to the common potential wiring while maintaining electrical isolation from the signal wiring. This segmentation prevents capacitive coupling between the shield electrode and signal wiring that would cause potential variation and image quality degradation, while still providing the common potential reference needed for LCD operation.
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 reduces signal delay, controls crosstalk and coloring, and maintains high aperture ratio by minimizing capacitance and potential variations, enhancing image quality and luminance uniformity.
Implementation Method 1
the insulation film arranged between the signal wiring 1 and the lower shield COM electrode 104 includes only the gate insulation film 22
Implementation Method 2
the gate insulation film 22 for forming a switching element 13 which includes a gate electrode, the signal wiring 1, a source electrode 11, and a semiconductor 12
Implementation Method 3
an electric field substantially parallel to the first substrate is applied between the pixel electrode and the counter electrode
Data Source
AI summary
A lateral electric field type liquid crystal display apparatus includes a first substrate on which pixels are disposed in a matrix shape, each of the pixels including a plurality of signal wirings and a plurality of scanning wirings which intersect each other, a switching element provided in a region adjacent to a portion in which the signal wiring and the scanning wiring intersect or on the scanning wiring, a pixel electrode connected to the switching element, and a counter electrode to which a common potential is supplied from a common potential wiring; a second substrate provided to face the first substrate; and a liquid crystal provided between the first and second substrates, wherein a first electric field shield electrode, which is set to the common potential, is provided between the signal wiring and the first substrate, and the first electric field shield electrode is electrically connected with a first wiring which supplies the common potential to the first electric field shield electrode, within a display region, and an electric field substantially parallel to the first substrate is applied between the pixel electrode and the counter electrode.