Head-Up Display VA Panel Wide Viewing Angle via Retardation Plates
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Solution Overview
Problem
Conventional liquid crystal displays for head-up displays face challenges in achieving a wide viewing angle, which is essential for multiple viewers, such as in vehicles, where the existing technologies like VA and IPS modes fail to provide the required performance.
Innovation Solution
The proposed solution involves a liquid crystal display configuration that includes a vertical alignment (VA) mode liquid crystal panel sandwiched by TAC films and retardation plates, where the TAC films act as negative C plates and the retardation plates impart a specific retardation, optimizing the refractive indices to reduce birefringence and enhance viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional VA or IPS liquid crystal display modes are used, then the display can be operated, but the viewing angle remains narrow and cannot satisfy multiple viewers
Solution Approach 1:
The patent employs a composite optical structure comprising multiple functional layers including a liquid crystal layer, a first retardation plate with specific Nz value (>0.9), a first TAC film with specific Nz value (0.3-0.7), a second retardation plate, and a second TAC film. Each layer has optimized optical properties that collectively compensate for viewing angle dependence and maintain display performance across wide viewing angles.
Solution Approach 2:
The patent optimizes specific optical parameters of the retardation plates and TAC films, particularly the Nz values (ratio of out-of-plane to in-plane refractive index). The first retardation plate has Nz>0.9, the first TAC film has 0.3≤Nz≤0.7, and the second TAC film has 0.3≤Nz≤0.7. These parameter optimizations enable wide viewing angle characteristics while maintaining reliable display performance.
2Ease of manufacture
If the liquid crystal display structure is simplified, then manufacturing becomes easier, but viewing angle performance deteriorates
Solution Approach 1:
The patent achieves wide viewing angle performance by optimizing the Nz parameters of standard commercial components (retardation plates and TAC films) rather than inventing new component types. This approach maintains ease of manufacture with conventional materials while achieving superior viewing angle characteristics through careful parameter selection and layer configuration.
Solution Approach 2:
The patent creates a composite optical system using commercially available retardation plates and TAC films arranged in a specific multi-layer configuration. This composite structure achieves wide viewing angle performance without requiring development of new materials, thus maintaining manufacturing simplicity while improving optical performance.
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 significantly improves the viewing angle and contrast ratio, particularly in oblique viewing conditions, making it suitable for head-up displays and other applications requiring wide viewing angles.
Implementation Method 1
the TAC films act as negative C plates and the retardation plates impart a specific retardation, optimizing the refractive indices to reduce birefringence
Implementation Method 2
the retardation plates impart a specific retardation, optimizing the refractive indices
Data Source
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AI summary
A liquid crystal display (1) includes: a liquid crystal panel (20) of a vertical alignment (VA) type; first and second TAC films (12-1), (12-2) which sandwich the liquid crystal panel (20); first and second retardation plates (11-1), (11-2) which sandwich the first and second TAC films (12-1), (12-2); and first and second polarizers (10-1), (10-2) which sandwich the first and second retardation plates (11-1), (11-2). The first and second polarizers (10-1), (10-2) include first and second absorption axes, respectively, which are substantially perpendicular to each other. The first and second retardation plates (11-1), (11-2) include first and second slow axes, respectively, which are substantially perpendicular to each other. The first and second slow axes intersect at about 45° with the first and second absorption axes, respectively.