Vertical Alignment LCD Viewing Angle Compensation
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Solution Overview
Problem
Liquid crystal display (LCD) devices face issues with viewing angle, particularly in twisted nematic (TN) mode, where gray inversion occurs when viewed from the sides, and vertical alignment (VA) mode devices require complex manufacturing processes to enhance viewing angles.
Innovation Solution
A transmission-type display device is designed with a panel comprising a TFT substrate and a color filter substrate separated by a vertical alignment liquid crystal layer, where the substrates are coated with retardation films and polarizing plates. The retardation films, including λ/4 films and C-plates, are strategically aligned to optimize the phase retardation value and slow axis orientation, enhancing the viewing angle without the need for complex manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a TN mode LCD device uses a wide view film, then the viewing angle becomes wider, but the gray inversion in the lower side and diagonal direction is not easily removed
Solution Approach 1:
The patent combines multiple functional films (retardation film, C-plate, and wide view film) in a specific layered configuration to achieve both wide viewing angle and gray inversion elimination. The composite structure includes a retardation film with specific retardation value (50-150 nm) and a C-plate with negative optical compensation, working together to compensate for viewing angle defects without requiring complex manufacturing processes
Solution Approach 2:
The patent optimizes specific optical parameters of the films, including the retardation value of the retardation film (50-150 nm) and the thickness of the C-plate (50-200 nm), to achieve the desired optical compensation effect. By carefully controlling these parameters, the device eliminates gray inversion while maintaining wide viewing angle characteristics
2Adaptability or versatility
If a VA mode LCD device uses PVA or MVA to enhance viewing angle, then the viewing angle improves, but the manufacturing process becomes complex
Solution Approach 1:
The patent extracts and eliminates the need for complex electrode patterns (PVA) or pixel division structures (MVA) by using a simpler film-based approach. The viewing angle enhancement is achieved through optical compensation films rather than complex liquid crystal alignment structures, significantly simplifying the manufacturing process while maintaining wide viewing angle performance
Solution Approach 2:
The patent replaces the mechanical/structural complexity of PVA or MVA electrode patterns with an optical solution using retardation films and C-plates. Instead of using complex liquid crystal alignment structures, the invention uses optical compensation to achieve wide viewing angle, substituting a simpler film deposition process for complex electrode fabrication
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
The solution significantly improves the viewing angle and reduces gray inversion across various directions, maintaining transmissivity and color accuracy, making it suitable for small-size, rotatable display devices like cellular phones and tablets.
Implementation Method 1
a phase retardation value (Δnd) of the liquid crystal layer is between about 250 nm and about 350 nm
Implementation Method 2
one of the first retardation film and the second retardation film comprises a λ/4 film and a C-plate and the other thereof comprises a λ/4 film
Implementation Method 3
Liquid crystal molecules of the liquid crystal layer rotate relative to an optic axis depending on an applied voltage
Implementation Method 4
The LCD device displays screen images by using an index of refraction anisotropy of the liquid crystal layer
Implementation Method 5
polarizing plates adhere to external surfaces of both substrates, respectively, of which transmitting axes of the respective polarizing plates are perpendicular to each other
Data Source
AI summary
A transmission-type display device, in which a viewing angle thereof is enhanced, comprises: an panel comprising a first substrate where TFTs are formed and a second substrate facing the first substrate; a first retardation film and a first polarizing plate which adhere sequentially to an external surface of the first substrate; and a second retardation film and a second polarizing plate which adhere sequentially to an external surface of the second substrate.