TFT Substrate Stepped Portion Angle Control for LCD Light Leakage
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Solution Overview
Problem
Liquid crystal display (LCD) devices face a challenge in maintaining a high contrast ratio due to contrast ratio deterioration caused by stepped portions on the TFT substrate, leading to light leakage and reduced image clarity.
Innovation Solution
The TFT substrate is designed with a pattern that induces a stepped portion on the protection layer, where the longitudinal direction of the pattern forms an angle of about 30 degrees to 60 degrees with respect to the substrate directions, and the inclination angle of the pattern's side is adjusted based on its thickness to minimize light leakage, thereby enhancing the contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a stepped portion is formed on the TFT substrate to define pixel regions, then pixel electrode formation and display region definition are improved, but light leakage occurs and contrast ratio deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the inclination angle of the pattern side face (30-60 degrees) and the pattern thickness (2000-3000 angstroms) to optimize the stepped portion geometry. This specific parameter configuration ensures that liquid crystal molecules are not vertically erected at the stepped portions, thereby preventing light leakage while maintaining ease of manufacture.
2Manufacturing precision
If the pattern thickness is increased to enhance structural definition, then pixel region boundary clarity is improved, but light leakage increases and contrast ratio deteriorates
Solution Approach 1:
The patent identifies that increasing pattern thickness beyond 3000 angstroms causes light leakage to increase. The optimal parameter configuration specifies a thickness range of 2000-3000 angstroms combined with a specific inclination angle range (30-60 degrees), which provides sufficient structural definition for pixel region boundaries while preventing light leakage.
3Object-affected harmful factors
If the pattern inclination angle is reduced to minimize light leakage, then contrast ratio is improved, but pixel region definition precision may be compromised
Solution Approach 1:
The patent establishes that the pattern inclination angle should be within 30-60 degrees to simultaneously achieve minimal light leakage and precise pixel region definition. This parameter range represents the optimal balance where the stepped portion geometry effectively prevents light leakage while maintaining clear pixel region boundaries.
Data Source
AI summary
An LCD device includes a first substrate having a first base substrate, patterns disposed at different heights with respect to the first base substrate, and an insulation layer formed on the first base substrate and the patterns. The insulation layer has raised portions corresponding to the patterns. A side of the raised portions forms an inclination angle of no more than about 45° when a height of the raised portions is more than about 3000 angstroms, the side of the raised portions forms an inclination angle of no more than about 50° when a height of the raised portions is in a range of about 2000 angstroms to about 3000 angstroms, and the side of the raised portions forms an inclination angle of no more than about 90° when a height of the raised portions is more than about 2000 angstroms. Therefore, light leakage may be minimized.