Extrafine Metal Wire Grid Polarizer for High Contrast LCDs
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Solution Overview
Problem
Conventional polarizing optical devices in LCDs suffer from low optical efficiency and high reflectance of ambient light, leading to decreased display contrast, especially in dark mode operations, and are challenging to manufacture in large sizes due to complex processes and material requirements.
Innovation Solution
A polarizing optical device featuring an extrafine metal structure with a specific directional arrangement and a metal compound part on its surface, where light polarized parallel to the direction is absorbed or reflected, and perpendicular light is transmitted, integrated with a transparent protective layer to enhance anti-reflection and optical efficiency, allowing for large-scale manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a dichroic polarizer is used, then linearly polarized light is obtained, but optical efficiency is very low due to natural light transmittance of about 50% or less
Solution Approach 1:
The patent changes the fundamental operating principle of the polarizer from absorption-type to reflection-type. By using a wire grid structure with metal wires having diameter much less than the wavelength of light, the device reflects TE-polarized light and transmits TM-polarized light, achieving high optical efficiency without the 50% transmission loss inherent in dichroic polarizers.
Solution Approach 2:
The patent replaces the chemical/dye-based absorption mechanism of dichroic polarizers with a physical reflection mechanism using a wire grid structure. This substitution of the underlying physical principle enables the polarizer to achieve high efficiency by reflecting unwanted polarization components rather than absorbing them.
2Use of energy by moving object
If a reflection type polarizer with wire grid structure is used, then optical efficiency is improved, but display contrast decreases due to reflection of TE polarized light component in ambient light
Solution Approach 1:
The patent merges the reflection-type wire grid structure with an absorption-type dichroic polarizer in a composite configuration. The wire grid reflects TE-polarized light back toward the backlight unit, while the dichroic polarizer absorbs any remaining TE components and prevents them from reaching the display, thereby maintaining high contrast while preserving optical efficiency.
Solution Approach 2:
The patent converts the harmful reflection of TE-polarized ambient light into a beneficial effect by directing it back toward the backlight unit through the wire grid structure. This reflected light can be reused or dissipated harmlessly, preventing it from degrading display contrast while maintaining the high optical efficiency of the reflection-type design.
3Object-affected harmful factors
If an extrafine metal grid structure is combined with an optical absorption type extrafine grid structure, then reflection of ambient light is minimized, but manufacturing complexity increases and large size manufacturing becomes difficult
Solution Approach 1:
The patent combines the wire grid structure and dichroic polarizer into a single integrated polarizing optical device with a unified substrate. This merging of components simplifies the manufacturing process and enables large-scale production while maintaining the dual functionality of reflecting and absorbing TE-polarized light to minimize ambient light reflection.
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 optical efficiency and reduces reflectance, enabling high contrast displays even in large LCDs by effectively managing light polarization and absorption, while simplifying the manufacturing process and reducing material complexity.
Implementation Method 1
when light is incident from the first major surface side, light polarized in a direction parallel to the specific direction is absorbed
Implementation Method 2
when light is incident from the second major surface side, light polarized in the direction parallel to the specific direction is reflected
Implementation Method 3
a metal compound part formed on surfaces of the extrafine metal structures
Data Source
AI summary
A polarizing optical device has first and second major surfaces. The polarizing optical device is provided at the first major surface thereof with extrafine structures made of a metal and arranged in a specific direction. The extrafine metal structures are provided at surfaces thereof with a metal compound part, the metal compound part being formed by performing surface treatment on the surfaces of the extrafine metal structures. When light is incident from the first major surface side, light polarized in a direction parallel to the specific direction is absorbed, and light polarized in a direction perpendicular to the specific direction is transmitted. When light is incident from the second major surface side, light polarized in the direction parallel to the specific direction is reflected, and light polarized in the direction perpendicular to the specific direction is transmitted.