Backlight Unit Air Gap for Luminance Loss Prevention
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Solution Overview
Problem
The luminance of liquid crystal display 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 color conversion layer converting blue light into green light, an optical sheet for diffusing or condensing the light, and an air gap between the color conversion layer and the optical sheet, ensuring that green light is not absorbed by the red light emitting material, thereby increasing luminance.
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 the light generation areas, green light is produced in the first region without being absorbed by the red fluorescent material in the second region, thereby preventing luminance loss.
Solution Approach 2:
The patent applies different fluorescent materials with specific optical properties to different local regions of the backlight unit. The green fluorescent material is positioned where green light needs to be generated, while the red fluorescent material is positioned where red light is needed. This local differentiation ensures that green light emitting areas do not overlap with red color absorption areas, maintaining high luminance in green regions.
2Productivity
If the green light emitting area overlaps with the red color absorption area, then both green and red light generation is attempted, but green light is absorbed by red fluorescent material, reducing overall light efficiency
Solution Approach 1:
The backlight unit is segmented into functionally distinct zones: a first region dedicated to green light generation using blue light sources and green fluorescent material, and a second region dedicated to red light generation using blue light sources and red fluorescent material. This segmentation eliminates overlap between green light emitting areas and red color absorption areas, ensuring that green light is not absorbed by red fluorescent material and thereby improving overall light efficiency.
Solution Approach 2:
The patent introduces a light guide plate as an intermediary component that distributes blue light from LED sources to both the green fluorescent material region and the red fluorescent material region. The light guide plate acts as a mediator that enables separate illumination paths, preventing direct interaction between green light and red fluorescent material, thus avoiding energy loss through absorption.
3Adaptability or versatility
If multiple fluorescent materials are placed in overlapping areas to generate different colors, then color coverage is improved, but absorption between different fluorescent materials reduces luminance
Solution Approach 1:
The patent segments the color generation function into separate spatial regions: green light is generated in a first region using green fluorescent material excited by blue light, while red light is generated in a second region using red fluorescent material excited by blue light. This segmentation allows the backlight unit to maintain broad color coverage (including both green and red) while preventing luminance loss by ensuring that green light does not pass through red fluorescent material and vice versa.
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 effectively enhances the luminance of the liquid crystal display device by spatially separating red and green light emissions, preventing absorption and improving light efficiency through the use of an air gap to minimize light loss during refraction.
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
Implementation Method 3
since the red fluorescent material absorbs the green light as much as an area R in which the green light emitting area overlaps the red color absorption area
Data Source
AI summary
The present disclosure is directed to a liquid crystal display device including a display panel including a red pixel, a green pixel, and a blue pixel; and a backlight unit which emits light to the display panel. The backlight unit includes a light source which outputs a first color light; a color conversion layer which is configured to convert the first color light into a second color light; an optical sheet which diffuses or condenses the second color light; and an air gap formed between the color conversion layer and the optical sheet.