Polysilicon Light-Shielding Structure for LCD Panel Contrast
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Solution Overview
Problem
Conventional LCD panels suffer from light leakage due to the floating light-shielding structure, which impairs contrast ratio, and existing solutions require additional photomask processing procedures to mitigate this issue, making them costly.
Innovation Solution
The use of a polysilicon layer as the light-shielding structure, where the gate conductor and first light-shielding structure are defined in the same photomask process, with additional polysilicon channel and light-shielding structures extending under crossover and contact hole regions to prevent light leakage without requiring extra photomask steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the light-shielding structure is extended to crossover regions to prevent light leakage, then contrast ratio is improved, but electrical connection between conductors is blocked
Solution Approach 1:
The patent resolves the conflict between light shielding and electrical connection by using vertical dimensionality. The light-shielding structure is positioned at specific vertical levels that avoid intersecting with conductors in crossover regions. The first and second light-shielding structure regions are arranged at different heights, allowing light shielding in some areas while maintaining electrical connectivity in others.
Solution Approach 2:
The light-shielding structure is selectively positioned only in regions where light shielding is needed, while avoiding areas where electrical connections must pass through. In crossover regions, the structure is configured to shield light from reaching the liquid crystal layer without extending into the path of conductors, thus maintaining local electrical connectivity while achieving global light shielding.
2Object-affected harmful factors
If an additional photomask processing procedure is used to form silicon nitride film for reducing light leakage, then light leakage is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines the light-shielding structure formation with the existing transistor electrode formation process. The light-shielding structure is formed using the same photomask and deposition steps that create the transistor electrodes, eliminating the need for separate photomask processing procedures. This merging of functions reduces manufacturing complexity and cost while effectively preventing light leakage.
Solution Approach 2:
The patent makes the transistor electrode material serve dual functions: as an electrical conductor for the transistor operation and as a light-shielding material to prevent light leakage. By using the same material layer for both purposes, the invention eliminates the need for additional light-shielding layers or processing steps, thereby reducing device complexity while maintaining light shielding efficacy.
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 approach effectively prevents light leakage in crossover and contact hole regions, enhancing contrast ratio without increasing fabrication costs by leveraging existing photomask processes.
Implementation Method 1
The use of a polysilicon layer as the light-shielding structure, where the gate conductor and first light-shielding structure are defined in the same photomask process
Data Source
AI summary
A display panel is used with an image display system. The display panel includes a light-transmissive substrate, a gate insulating layer, a gate conductor, a first light-shielding structure, a channel layer and a second light-shielding structure. The gate insulating layer is formed over the light-transmissive substrate. The gate conductor and the first light-shielding structure are made of the same material, formed over the gate insulating layer, and electrically isolated from each other. The first light-shielding structure has a hollow portion. The channel layer and the second light-shielding structure made of the same material and formed over the light-transmissive substrate but under the gate insulating layer. The second light-shielding structure is disposed under the hollow portion of the first light-shielding structure.