LED Backlight Refractive Cover for Thin Uniform Displays
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Solution Overview
Problem
Display apparatuses face challenges in maintaining uniform brightness and reducing material costs as they become thinner, with decreasing optical distances affecting light emission distribution and increasing the risk of mura (non-uniform brightness) due to fewer point light sources.
Innovation Solution
Incorporating a light emitting diode (LED) with a distributed Bragg reflector (DBR) layer and a refractive cover formed by dispensing a transparent material to enhance light extraction efficiency and diffusion, while using a refractive cover to provide uniform backlight even with a short optical distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the display apparatus is made thinner, then the optical distance is decreased, but the uniformity of brightness deteriorates and mura occurs
Solution Approach 1:
A refractive cover is introduced as an intermediary component between the LED and the liquid crystal panel. This refractive cover has a specific refractive index that differs from both the LED封装 material and the liquid crystal panel, serving as an optical mediator to improve light extraction efficiency and distribute light more uniformly across the display area, thereby preventing mura while maintaining thin design
Solution Approach 2:
The patent changes the refractive index parameter by selecting specific materials for the refractive cover (with refractive index between 1.4-1.7) and adjusts the optical distance parameter to optimize light extraction. By controlling these optical parameters, the system achieves uniform brightness distribution even with reduced thickness
2Quantity of substance
If the number of LEDs is reduced, then material costs are decreased, but the uniformity of backlight deteriorates and mura occurs
Solution Approach 1:
The refractive cover acts as an optical intermediary that compensates for the reduced number of light sources. By optimizing light extraction from each individual LED through the refractive cover's specific refractive index and geometric design, the system achieves uniform backlight distribution across the entire display area even with fewer LEDs, thereby reducing material costs while maintaining uniformity
Solution Approach 2:
The refractive cover is designed with specific local optical properties (refractive index gradient, surface geometry) that enhance light extraction efficiency at each LED location. This localized optimization ensures that each reduced number of LEDs contributes uniformly to the overall backlight, preventing mura while minimizing material usage
3Ease of manufacture
If a conventional LED structure is used, then manufacturing is simpler, but light extraction efficiency is low and brightness uniformity is poor
Solution Approach 1:
The refractive cover serves as an intermediary optical element that can be integrated into the existing LED manufacturing process. It is positioned between the LED and the liquid crystal panel, requiring minimal additional manufacturing steps while dramatically improving light extraction efficiency and brightness uniformity through its specific refractive index properties
Solution Approach 2:
The refractive cover performs multiple functions simultaneously: it protects the LED, enhances light extraction efficiency, improves brightness uniformity, and maintains compatibility with thin display designs. This multi-functionality achieves significant performance improvement without substantially complicating the manufacturing process
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 enhances light emission distribution, reduces material costs, and maintains uniform brightness without mura, even with a reduced number of LEDs, thereby improving the display quality and efficiency of the display apparatus.
Implementation Method 1
a light emitting diode (LED) with a distributed Bragg reflector (DBR) layer arranged on top of the LED
Implementation Method 2
a refractive cover covering the LED to protect the LED and enhance light extraction efficiency and light diffusion performance of the LED
Data Source
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AI summary
A display apparatus includes a liquid crystal panel, and a backlight unit configured to emit light to the liquid crystal panel. The backlight unit includes a substrate, a light emitting diode (LED) provided on the substrate and configured to emit light, and a refractive cover formed by being provided at a plurality of points separated from each other, and configured to enclose the LED.