Backlight Unit Air Gap for Green Light Luminance
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Solution Overview
Problem
The luminance of liquid crystal display (LCD) devices is reduced due to the absorption of green light by red fluorescent materials in backlight units, where the green light emitting area overlaps with the red color absorption area, leading to inefficient light transmission.
Innovation Solution
A backlight unit design that includes a light source emitting a first color light, a color conversion layer converting the first color light into a second color light, an optical sheet for diffusing or condensing the second color light, and an air gap between the color conversion layer and the optical sheet, specifically to separate and enhance the emission of green light by preventing its absorption by red light emitting materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a green fluorescent material is used to generate green light by absorbing blue light, then green light is produced, but the red fluorescent material absorbs the green light in the overlapping area, reducing luminance
Solution Approach 1:
The patent divides the backlight unit into distinct regions: a first region with blue light sources and green fluorescent material, and a second region with red fluorescent material. By spatially segmenting these components, the patent prevents the red fluorescent material from absorbing green light, thereby resolving the luminance reduction problem while maintaining color conversion functionality.
Solution Approach 2:
The patent applies different properties to different regions of the backlight unit. The first region is optimized for green light generation with blue LEDs and green fluorescent material, while the second region is optimized for red light generation. This local differentiation ensures that green light is not absorbed by red fluorescent material, preserving luminance in the green region.
2Area of stationary object
If red and green light emitting areas are overlapped to save space, then device compactness is improved, but green light is absorbed by red fluorescent material reducing light transmission efficiency
Solution Approach 1:
The patent segments the backlight unit into adjacent first and second regions with different light emitting functions. The first region generates green light while the second region generates red light, preventing spatial overlap that would cause green light absorption. This segmentation maintains area efficiency while preserving light transmission efficiency.
Solution Approach 2:
The patent introduces a reflective plate as an intermediary element between the first and second regions. This reflective plate redirects light paths and helps maintain distinct functional zones, preventing harmful interactions between red and green light emitting areas while preserving overall compactness.
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 configuration increases the luminance of the display by spatially separating red and green light emissions, preventing the red light emitting material from absorbing green light and enhancing light transmission to the LCD panel, thereby improving luminance and color reproduction.
Implementation Method 1
the green light is generated by absorbing, by a green fluorescent material, the blue light
Implementation Method 2
an optical sheet which diffuses or condenses the second color light
Data Source
AI summary
The present disclosure is directed to a liquid crystal display device including a display panel having a red pixel, a green pixel, and a blue pixel; and a backlight unit configured to emit light to the display panel. The backlight unit includes a light source which outputs a first color light; a color conversion layer configured to convert the first color light into a second color light such that red light and green light are spatially separated; and an optical sheet which diffuses or condenses the second color light.