Color Conversion Sheet Backlight Unit with Reflection Filters
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Solution Overview
Problem
Existing display devices face challenges in achieving high image quality and luminance efficiency while reducing the thickness of the backlight unit, as the optical gap between the light source and the display panel is insufficient, leading to power consumption issues and component reliability problems.
Innovation Solution
A backlight unit design incorporating a color conversion sheet with a first and second color conversion layer, and reflection filters to minimize light loss, particularly in the green wavelength band, and a light conversion pattern to prevent hot spots, ensuring improved image quality and luminance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the thickness of the backlight unit is reduced, then the thickness of the display device is reduced, but the optical gap between the light source and the display panel becomes insufficient, degrading image quality
Solution Approach 1:
The color conversion sheet is divided into multiple color conversion layers (first color conversion layer, second color conversion layer, third color conversion layer) with different functions. Each layer converts specific wavelength bands separately, allowing optimized light path management in a thin structure while maintaining image quality through systematic wavelength separation and conversion.
Solution Approach 2:
Reflection filters are introduced as intermediary elements between color conversion layers. These filters reflect specific wavelength bands (e.g., reflecting green light from the first color conversion layer back through the layer to prevent re-absorption by the second color conversion layer), mediating the interaction between different color conversion layers to minimize light loss and maintain image quality in a reduced thickness configuration.
2Illumination intensity
If the luminance efficiency of the backlight unit is poor, then high current must be applied to achieve high brightness, increasing power consumption and degrading component reliability
Solution Approach 1:
The patent optimizes the emission wavelengths and conversion efficiencies of multiple color conversion materials. The first color conversion layer converts blue light to green, the second converts blue to red, and the third converts blue to yellow-green, with each material selected for optimal conversion efficiency. This parameter optimization across multiple wavelength conversions improves overall luminance efficiency, reducing the current needed to achieve high brightness and lowering power consumption.
3Reliability
If multiple color conversion layers are stacked to improve color quality, then light loss increases due to repeated absorption and re-emission, degrading luminance efficiency
Solution Approach 1:
Reflection filters serve as intermediaries between color conversion layers to prevent light loss. The first reflection filter reflects green light from the first color conversion layer back through the layer, preventing re-absorption by the second color conversion layer. The second reflection filter reflects red light from the second color conversion layer to prevent re-absorption. This intermediary reflection mechanism maintains image quality through proper wavelength separation while minimizing energy loss from repeated absorption cycles.
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 image quality and luminance efficiency by minimizing light loss and preventing hot spots, reducing power consumption, and improving component reliability, while maintaining a reduced backlight unit thickness.
Implementation Method 1
a first color conversion layer configured to react to light in a first wavelength band and emit light in a second wavelength band
Implementation Method 2
a second color conversion layer positioned between the light sources and the first color conversion layer and configured to react to light in at least a portion of the first wavelength band and the second wavelength band and emit light in a third wavelength band
Implementation Method 3
a first reflection filter positioned between the first color conversion layer and the second color conversion layer, and configured to separate the first color conversion layer from the second color conversion layer and to reflect light in at least a portion of the second wavelength band
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
Embodiments of the present disclosure relate to a color conversion sheet, a backlight unit, and a display device, in which a color conversion sheet realizing white light from blue light includes a green reflection filter positioned between a green color conversion layer and a red color conversion layer, thereby independently exciting the green light and the red light and increasing the amount of green light supplied to the display panel while preventing the green light from being excited into red light. Therefore, it is possible to increase the brightness of white light supplied through the color conversion sheet and provide a backlight unit with improved luminance efficiency.