Backlight Unit Light Conversion Layer Color Purity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid crystal display (LCD) devices face challenges with non-uniform luminance and reduced color purity when using cold cathode fluorescent lamps (CCFLs) as backlight sources, and while three-color LEDs improve color purity, they are costly; there is a need for a lower-cost light source that maintains color reproducibility and purity.
Innovation Solution
A backlight unit for LCDs incorporating a light emitting diode (LED) light source with a light conversion layer containing semiconductor nanocrystals and a polymer matrix, which converts LED light into white light, including a polymer with carboxylic acid groups and thermoplastic second polymers, and optionally featuring diffusion plates, prism sheets, and brightness enhancement layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a white LED is used as a light source to reduce cost, then manufacturing cost is reduced, but color purity and color reproducibility deteriorate
Solution Approach 1:
The patent uses a composite light conversion layer containing both yellow phosphor and red phosphor particles dispersed in a polymer matrix. This composite material approach combines the cost-effectiveness of white LED with improved color purity by utilizing the complementary absorption and emission characteristics of different phosphor materials to achieve better spectral distribution.
Solution Approach 2:
The patent applies different phosphor materials with specific properties to different regions or aspects of the light conversion process. By selecting phosphors with specific particle sizes, shapes, and compositions, the invention optimizes local light conversion characteristics to improve overall color purity while maintaining cost efficiency.
2Manufacturing precision
If a light conversion layer is disposed apart from the LED light source, then color purity is improved, but light loss increases
Solution Approach 1:
The patent introduces a light guide panel as an intermediary component between the LED light source and the light conversion layer. This light guide panel efficiently transports light from the LED to the separated light conversion layer, minimizing light loss during transmission while maintaining the spatial separation necessary for achieving high color purity.
3Loss of energy
If the light conversion layer is disposed close to the LED light source, then light loss is reduced, but color purity deteriorates
Solution Approach 1:
The light guide panel serves as a mediator that enables the light conversion layer to be positioned optimally. It transmits light efficiently over the necessary distance, allowing the light conversion layer to be disposed apart from the LED for improved color purity without suffering excessive light loss.
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 provides improved color reproducibility and purity while reducing costs by using an LED light source with a light conversion layer that maintains luminance over extended periods, as demonstrated by the maintenance of luminance in the fabricated backlight units.
Implementation Method 1
a light conversion layer disposed apart from the LED light source, wherein the light conversion layer is configured to convert light emitted from the LED light source to white light
Implementation Method 2
the light conversion layer includes a semiconductor nanocrystal and a polymer matrix
Data Source
AI summary
A backlight unit for a liquid crystal display device including an light emitting diode light source; a light conversion layer disposed apart from the light emitting diode light source, wherein the light conversion layer is configured to convert light emitted from the light emitting diode light source to white light and provide the white light to a liquid crystal panel; and a light guide panel disposed between the light emitting diode light source and the light conversion layer, wherein the light conversion layer includes a semiconductor nanocrystal and a polymer matrix, wherein the semiconductor nanocrystal is coated with a first polymer, and wherein the polymer matrix comprises a thermoplastic second polymer.