LCD Passivation Layer Inclined Planes Light Leakage
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Solution Overview
Problem
Conventional liquid crystal display devices face issues with light leakage due to uncontrolled rotation of liquid crystal molecules, parasitic capacitance from metallic black matrices, and manufacturing challenges with thick, rugged polymeric black matrices, which affect image contrast and the orientation of liquid crystal molecules.
Innovation Solution
A lower substrate with inclined planes forming depressions or cavities on the thin-film transistor electrodes and metal lines, using transparent passivation materials like silicon oxide or silicon nitride, to refract and divert incident light, thereby blocking it and preventing current leakage and parasitic capacitance, while allowing for adjustable thickness and smoother surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a metallic black matrix is used to block light leakage, then light shielding effectiveness is improved, but parasitic capacitance and heavy metal pollution increase
Solution Approach 1:
The patent extracts the light-blocking function from the traditional metallic black matrix and relocates it to the lower substrate through groove structures. The grooves are filled with transparent dielectric material, eliminating the need for metallic black matrix while maintaining light shielding effectiveness and removing parasitic capacitance issues.
Solution Approach 2:
The patent introduces transparent dielectric material as an intermediary substance to fill the grooves in the lower substrate. This intermediary material provides optical shielding while being electrically insulating, thus blocking light leakage without generating parasitic capacitance like metallic materials would.
2Object-affected harmful factors
If a polymeric black matrix is used to block light leakage, then light shielding is achieved, but total thickness becomes excessive and surface becomes rugged
Solution Approach 1:
The patent segments the light-blocking function by creating discrete groove structures in the lower substrate rather than using a continuous thick polymeric layer. The grooves are filled with transparent dielectric material, providing localized light shielding with minimal overall thickness and smooth surfaces.
Solution Approach 2:
The patent transitions from a thickness-based light-blocking approach (thick polymeric layer) to a geometric structure-based approach (grooves in the lower substrate). By utilizing the third dimension (depth of grooves) and optical refraction principles, effective light shielding is achieved with much reduced material thickness.
3Object-affected harmful factors
If a thick polymeric black matrix is used, then light shielding is improved, but manufacturing difficulty increases due to lithography interference
Solution Approach 1:
The patent extracts the lithography process from the polymeric black matrix formation and integrates it into the groove structure formation in the lower substrate. The transparent dielectric material in the grooves does not interfere with subsequent lithography processes, improving manufacturing efficiency while maintaining light shielding.
4Object-affected harmful factors
If a thick polymeric black matrix is used, then light shielding is improved, but surface ruggedness increases affecting rubbing process
Solution Approach 1:
The patent segments the light-blocking function into discrete groove structures rather than using a continuous thick polymeric layer. This segmentation results in a smooth overall surface profile that is suitable for subsequent rubbing processes while maintaining effective light shielding through the groove geometry and dielectric material.
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
Effectively blocks incident light in specific regions, improving image contrast and preventing current leakage, while using transparent materials to mitigate parasitic capacitance and manufacturing issues associated with metallic and polymeric black matrices.
Implementation Method 1
The lower substrate for a liquid crystal display device illustrated suppress or reduce the direct transmission light by way of refraction
Data Source
AI summary
A liquid crystal display device is disclosed, which comprises an upper substrate, a lower substrate, and a liquid crystal layer. The lower substrate has several pixel electrodes, metal lines, and switch elements thereon. Each switch element comprises a source electrode, a drain electrode, a gate electrode, and an opening between the source electrode and the drain electrode. A passivation layer covering the surface of the source electrode and the drain electrode forms two inclined planes separately on two sides. The two inclined planes face each other and are locating on a kink or step of the source electrode and drain electrode. The inclined planes also contact each other at the upper side of the opening. The inclinations of the inclined planes to the lower substrate are in a range from 5 to 50 degrees.