Oxide TFT LCD Panel Light Shielding for Threshold Stability
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Solution Overview
Problem
Liquid crystal display panels using oxide semiconductors for TFT channel layers face reliability issues due to light-induced threshold changes, particularly with short-wavelength visible light, leading to reduced display quality and reliability.
Innovation Solution
The liquid crystal display panel design includes thin film transistors with oxide semiconductor channel layers, where the transistors associated with primary colors are positioned to minimize exposure to the shortest wavelength light, and a light-shielding layer is used to suppress light entry, thereby reducing threshold shifts and maintaining display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If red color filter patterns are disposed in positions facing TFTs in blue and green subpixel formation portions to prevent short-wavelength light entry, then reliability of TFTs is improved, but display quality degrades due to red light leakage mixing in blue or green display
Solution Approach 1:
The patent applies local quality by disposing light-shielding layers selectively only in positions facing TFTs in subpixel formation portions associated with primary colors having the shortest wavelengths (blue and violet), while leaving other regions without light-shielding layers. This localized approach prevents short-wavelength light from affecting vulnerable TFTs while avoiding red light leakage into other color regions, thus resolving the contradiction between improving TFT reliability and maintaining display quality.
2Reliability
If light-shielding layers are disposed in positions facing all TFTs to prevent light entry, then threshold shifts are reduced, but display quality degrades due to red light leakage and increased device complexity
Solution Approach 1:
The patent implements local quality by selectively positioning light-shielding layers only where needed - specifically in front of TFTs in subpixel formation portions for primary colors with the shortest wavelengths. This selective placement reduces threshold shifts in vulnerable TFTs while avoiding unnecessary structural complexity in other regions, and prevents red light leakage into non-blue/violet regions.
Solution Approach 2:
Instead of uniformly shielding all TFTs (which would cause red light leakage and increase complexity), the patent inverts the approach by selectively shielding only specific TFTs that are most vulnerable to short-wavelength light. This inverted selective shielding strategy achieves the desired threshold stability while avoiding the negative effects of comprehensive shielding.
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 enhances the reliability of thin film transistors and prevents degradation in display quality by minimizing light-induced threshold shifts, ensuring improved performance and image fidelity.
Implementation Method 1
the electrical conductivity level changes on the short wavelength side of visible light due to optical absorption
Data Source
AI summary
There is provided a liquid crystal display panel that improves the reliability of thin film transistors while suppressing a degradation in display quality. A G TFT (120g) connected at its drain electrode (125d) to a G pixel electrode (130g) is disposed on the opposite side of the G pixel electrode (130g) from a B pixel electrode (130b). The distance between a B TFT (120b) connected at its drain electrode (125d) to the B pixel electrode (130b) and the B pixel electrode (130b) is greater than the distance between the G TFT (120g) connected at its drain electrode (125d) to the G pixel electrode (130g) and the G pixel electrode (130g). The distance between an R TFT (120r) connected at its drain electrode (125d) to an R pixel electrode (130r) and the B pixel electrode (130b) is greater than the distance between the B TFT (120b) connected to the B pixel electrode (130b) and the B pixel electrode (130b).