LED Display Reflective Layer Layout for Light Conversion Efficiency
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Solution Overview
Problem
Display devices face challenges in maximizing light extraction efficiency and minimizing total reflection, leading to reduced luminance and increased power consumption due to the thickness of light conversion layers and the placement of light conversion layers relative to LEDs.
Innovation Solution
A display device design featuring a substrate with a first reflective layer, LEDs, and light conversion layers where the second reflective layers cover the LEDs to reflect longer wavelengths upward, and the light conversion layers are positioned below the LEDs to reduce total reflection and enhance external quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light conversion layers are placed above LEDs to convert light, then light conversion function is achieved, but total reflection increases and light extraction efficiency decreases
Solution Approach 1:
The patent inverts the conventional structure by placing light conversion layers below the LEDs instead of above them. This inversion allows the light conversion layers to be positioned on the rear surface of the display device, enabling light from the LEDs to pass through the front surface after conversion, thereby reducing total reflection and improving light extraction efficiency while maintaining the light conversion function.
Solution Approach 2:
The patent changes the spatial dimension of light conversion by moving the conversion layers from the front (above LEDs) to the rear (below LEDs) of the display structure. This dimensional repositioning allows light to travel through the front surface after conversion, utilizing a different optical path that avoids total reflection issues associated with front-placed conversion layers.
2Productivity
If light conversion layers are made thicker to improve conversion efficiency, then light conversion performance improves, but device thickness increases and external quantum efficiency decreases
Solution Approach 1:
By relocating light conversion layers to the rear surface of the display device, the patent enables thicker conversion layers to be used without increasing the front profile thickness. The light conversion process occurs in the rear dimension, allowing sufficient conversion thickness while maintaining a thin front display surface, thereby improving external quantum efficiency.
3Device complexity
If conventional light conversion layer placement is used, then structure is simple, but light extraction efficiency is reduced and luminance decreases
Solution Approach 1:
The patent inverts the light conversion layer placement from above to below the LEDs, which initially increases structural complexity. However, this inversion dramatically improves light extraction efficiency and luminance by eliminating total reflection, ultimately creating a more efficient optical system that justifies the increased structural complexity.
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 light emission outside the device, reduces power consumption, and stabilizes light conversion layers by forming them on a separate substrate, achieving higher luminance and efficiency with thinner light conversion layers.
Implementation Method 1
a plurality of second reflective layers disposed to cover at least a portion of the plurality of blue LEDs. The plurality of second reflective layers reflects blue light emitted from the plurality of blue LEDs toward the plurality of light conversion layers
Implementation Method 2
light having a wavelength longer than that of the light emitted from the plurality of LEDs is emitted upwardly from the plurality of LEDs
Implementation Method 3
light emitted from the plurality of LEDs is reflected by the plurality of second reflective layers, and light having a wavelength longer than that of the light emitted from the plurality of LEDs is emitted upwardly from the plurality of LEDs
Data Source
AI summary
A display device includes a substrate on which a plurality of sub-pixels are disposed, a first reflective layer disposed on the substrate, a plurality of LEDs disposed in each of the plurality of sub-pixels on the first reflective layer, a plurality of light conversion layers disposed between the first reflective layer and the plurality of LEDs, and a plurality of second reflective layers covering at least a portion of the plurality of LEDs. Light emitted from the plurality of LEDs is reflected by the plurality of second reflective layers, and light having a wavelength longer than that of the light emitted from the plurality of LEDs is emitted upwardly from the plurality of LEDs.