Polarizing Waveguide Plate for Edge-Lit LCD Light Efficiency
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Solution Overview
Problem
Conventional edge-lit liquid crystal displays (LCDs) suffer from reduced light intensity due to absorption by polarizer films, leading to dimmed images and the need for larger, more power-consuming edge lights to compensate for lost light intensity.
Innovation Solution
A polarizing waveguide plate comprising a pair of spaced, parallel transparent plates with a composite mixture of liquid crystal and polymer materials, where an edge light emits unpolarized light that is scattered and converted to a single polarization direction, with a converter/reflector ensuring all light is polarized and reflected back into the waveguide for efficient emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a polarizer film is used to polarize unpolarized light in conventional edge-lit displays, then the light is linearly polarized and can pass through the display, but half of the light intensity is absorbed and wasted, resulting in dimmed images
Solution Approach 1:
The patent changes the polarization state parameter of light from unpolarized to linearly polarized through the liquid crystal layer, enabling full light transmission without the 50% loss inherent in conventional polarizer films. The liquid crystal material's optical properties are utilized to rotate the polarization plane of light, allowing both orthogonal polarization components to be converted into a single polarization direction that can pass through the display stack.
Solution Approach 2:
The patent employs a composite structure combining liquid crystal material with specific alignment layers and optical compensating films. This composite material system works together to achieve polarization conversion while maintaining high light transmission efficiency, replacing the need for absorbing polarizer films with a non-absorbing optical path.
2Illumination intensity
If the edge light is made larger to compensate for light absorption, then the light intensity is sufficient, but the display becomes less compact and consumes more power
Solution Approach 1:
By changing the polarization conversion mechanism from absorption-based to rotation-based, the patent enables sufficient light intensity with a smaller, more energy-efficient edge light source. The liquid crystal layer rotates the polarization plane of light without absorbing it, allowing the full output of a compact LED edge light to be utilized.
3Illumination intensity
If a conventional polarizer film is used, then the light is polarized, but the display structure becomes more complex with additional layers required
Solution Approach 1:
The patent merges the polarization function with the existing liquid crystal display structure. The liquid crystal layer, which is already present in the display for its primary function, is configured to perform polarization conversion, eliminating the need for separate polarizer films and reducing overall structural complexity.
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
Enhances light efficiency and intensity output from edge-lit displays by converting unpolarized light into polarized light, reducing the need for larger edge lights and minimizing power consumption.
Implementation Method 1
the liquid crystal material scatters at least a first portion of the unpolarized light out of the waveguide with a polarization in a first direction
Implementation Method 2
the converter/reflector converts light with a polarization to orthogonal to the first polarization into the first polarization and reflects it back into the waveguide
Data Source
AI summary
A polarizing waveguide plate includes a pair of spaced transparent plates that define a gap therebetween. Disposed within the gap is a composite material formed of a mixture of polymer mater and liquid crystal material. Positioned proximate to one edge of the gap is an edge light, while a reflector/converter is positioned proximate to another edge of the gap. During operation, unpolarized light is emitted from the edge light and is received within the gap. As such, a portion of the light polarized in a first direction is permitted to exit the waveguide, while the remaining portion of the light that is polarized in a second direction, orthogonal to the first direction, is converted by the converter/reflector so that its polarization is also in the first direction. As such, substantially all of the unpolarized light from the edge light is emitted by the polarizing waveguide plate as polarized light.