Optical Compensator Retardation for LCD Viewing Angle
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Solution Overview
Problem
Conventional compensation films for liquid crystal displays (LCDs) are optimized for a single wavelength of light, failing to address color shift and narrow viewing angle issues due to dark-state light leakage at large viewing angles, which reduces contrast.
Innovation Solution
The use of optimized A-plates and C-plates, as well as biaxial plates, with specific retardation values for blue and red light wavelengths, are introduced between the polarizers in an LCD to reduce dark-state light leakage and enhance contrast by considering the entire visible spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional compensation films optimized for a single wavelength are used, then manufacturing simplicity is maintained, but color shift and narrow viewing angle occur due to dark-state light leakage
Solution Approach 1:
The patent divides the compensation film into multiple layers, each optimized for specific wavelength ranges (blue, green, red). This segmentation allows each layer to independently compensate for dark-state light leakage at its target wavelength, thereby improving overall viewing angle performance without complicating the manufacturing process excessively.
Solution Approach 2:
The patent employs composite compensation films combining multiple materials with different optical properties. Each material is selected for its specific retardation characteristics at particular wavelengths, creating a composite structure that provides comprehensive compensation across the visible spectrum while maintaining manufacturability.
2Device complexity
If conventional compensation films optimized for a single wavelength are used, then device complexity is reduced, but contrast ratio deteriorates due to dark-state light leakage at large viewing angles
Solution Approach 1:
The compensation is segmented into multiple wavelength-specific layers, with each layer targeting a particular color range. This segmentation enables precise control over dark-state light leakage for each wavelength, thereby improving contrast ratio without requiring overly complex device structures.
Solution Approach 2:
The patent changes the optical parameters (retardation values, thickness) of the compensation film layers to be wavelength-dependent. By adjusting these parameters for each layer to match specific wavelength requirements, the system achieves superior contrast ratio while maintaining reasonable device complexity.
3Quantity of substance
If single-wavelength optimized compensation films are used, then production cost is reduced, but viewing angle characteristics deteriorate due to inadequate compensation at other wavelengths
Solution Approach 1:
The compensation film is segmented into multiple layers, each optimized for specific wavelength ranges (blue, green, red). This segmentation enables the system to provide adequate compensation across the entire visible spectrum, improving viewing angle characteristics while keeping production costs manageable through targeted optimization rather than universal over-engineering.
Solution Approach 2:
The multi-layer compensation film structure provides universal compensation across multiple wavelength ranges simultaneously. Each layer serves a specific function at its target wavelength, but collectively they provide comprehensive viewing angle compensation for all visible colors, enhancing adaptability without proportionally increasing cost.
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
These optimized optical compensators significantly reduce light leakage at various viewing angles, resulting in improved contrast and viewing angle characteristics for liquid crystal displays.
Implementation Method 1
An A-plate optimized for blue light (450 nm) has in-plane retardation R0=(nx−ny)×d at wavelengths of 450 nm and 550 nm satisfying the following formula (1)
Implementation Method 2
a C-plate optimized for blue light (450 nm) has retardation satisfying the following formula (2): 1(450)/Rth(550)
Data Source
AI summary
Embodiments of an optical compensator for a liquid crystal display is disclosed. One embodiment of the optical compensator includes an A-plate and a C-plate wherein:the retardation of the A-plate satisfies the following formula:0.644<R0(450)/R0(550)<1the retardation of the C-plate satisfies the following formula:1<Rth(450)/Rth(550)<1.35where R0(450) and R0(550) represent the retardation of the A-plate at wavelengths of 450 nm and 550 nm, respectively, and Rth(450) and Rth(550) are the values calculated by Rth=[[nx+ny]/2−nz]×d (where nx, ny and nz represent the three-dimensional refractive indexes of the C-plate as the refractive indexes in the direction of the x-axis, y-axis and z-axis, respectively, and d represents the thickness of the C-plate) for the C-plate at a wavelength of 450 nm and 550 nm, respectively. Other embodiments are also included.