Nanostructured Light Extraction Layer for Display Devices
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Solution Overview
Problem
Existing display devices with luminescent nanostructure-based color conversion layers face challenges in achieving high light extraction efficiency due to total internal reflection, which results in significant optical losses.
Innovation Solution
The implementation of a light extraction layer with nanostructured features that provide a non-uniform interface between the luminescent nanostructure-based color conversion layer and the emitting medium, thereby reducing or preventing total internal reflection and enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar top surface is used in the NS-based CC layer, then the device structure is simple and easy to manufacture, but total internal reflection occurs significantly, resulting in low light extraction efficiency
Solution Approach 1:
The patent applies curvature by replacing the planar top surface with a curved surface having a specific radius of curvature (R). This curved surface prevents total internal reflection by ensuring that light rays incident from the NS-based CC layer onto the interface do not exceed the critical angle, thereby significantly improving light extraction efficiency while maintaining manufacturing feasibility through conventional lamination processes
Solution Approach 2:
The patent introduces a light extraction layer as an intermediary component between the NS-based CC layer and the external medium. This light extraction layer with its curved surface acts as a mediator that facilitates light extraction by preventing total internal reflection, thereby improving light extraction efficiency without complicating the manufacturing process of the NS-based CC layer itself
2Illumination intensity
If the refractive index of the NS-based CC layer is higher than the surrounding medium, then light emission is enhanced, but total internal reflection increases, causing significant optical losses
Solution Approach 1:
The curved surface with specific radius of curvature modifies the geometry of the interface between the high refractive index NS-based CC layer and the surrounding medium. This curvature ensures that light rays, despite the high refractive index difference, do not undergo total internal reflection by maintaining incident angles below the critical angle, thus preserving both high light emission intensity and reducing optical losses
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 approach significantly increases the light extraction efficiency of display devices, achieving efficiencies greater than 50%, 60%, 70%, or 80%, while also improving color gamut coverage by reducing unwanted light leakage.
Implementation Method 1
a significant amount of the light generated by the NSs is reflected back into the CC layers through total internal reflection
Implementation Method 2
since these layers typically have a higher refractive index relative to the medium into which the light is emitted
Data Source
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AI summary
Embodiments of a display device are described. A display device includes a backlight unit having a light source and a liquid crystal display (LCD) module. The LCD module includes a nanostructure-based color conversion (NS-based CC) layer and a light extraction layer. The NS-based CC layer is configured to receive a primary light, from the light source, having a first peak wavelength and to convert a portion of the primary light to emit a first portion of a secondary light having a second peak wavelength. The second peak wavelength is different from the first peak wavelength. The light extraction layer is optically coupled to the NS-based CC layer and is configured to prevent total internal reflection of a second portion of the secondary light. The light extraction layer has patterned features with one or more dimension in nanometer scale.