Stacked Light-Conversion Layers for Display Devices
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Solution Overview
Problem
Liquid crystal display (LCD) devices suffer from low light energy utilization efficiency and limited viewing angle due to the color filtering mechanism, which results in significant light energy loss and restricted viewing angles, and the manufacturing process of photoluminescent display devices faces challenges with pixel alignment and production costs.
Innovation Solution
A photoluminescent display device with a stacked light-conversion layer arrangement, where the green light-conversion layer covers both red and green pixel regions, and the red light-conversion layer is disposed on top, allowing for easier alignment and improved light energy utilization by converting blue light into red and green light without significant absorption, thereby enhancing viewing angles and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a pixelated color filter layer is used to display colors, then color display is achieved, but light energy loss increases significantly (about two-thirds of light spectrum blocked)
Solution Approach 1:
The patent replaces the traditional color filter layer with a photoluminescent layer that converts blue light into red and green light through photoluminescent materials. This color conversion approach allows the backlight unit to emit only blue light while the photoluminescent layer generates the full color spectrum, eliminating the need to block two-thirds of the light spectrum as in traditional color filtering methods.
2Illumination intensity
If white light is used to pass through color filter pixels, then color display is achieved, but light transmission rate decreases (only 4% to 10% transmitted)
Solution Approach 1:
The patent changes the approach from filtering white light to generating colors through photoluminescent conversion of blue light. The photoluminescent layer contains red and green photoluminescent materials that convert blue light into red and green wavelengths, respectively, allowing much higher light transmission rates compared to traditional color filtering.
3Illumination intensity
If traditional LCD color filtering mechanism is used, then color display is achieved, but viewing angle is limited
Solution Approach 1:
The patent eliminates the color filter layer and uses photoluminescent materials to generate colors. This approach, combined with the blue light source and photoluminescent conversion, inherently provides wider viewing angles compared to traditional LCDs with color filters, as the photoluminescent emission is less directional and more uniform across viewing angles.
4Illumination intensity
If photoluminescent display device is manufactured with side-by-side red and green photoluminescent pixels, then color display is achieved, but manufacturing complexity and alignment precision requirements increase
Solution Approach 1:
The patent merges the red and green photoluminescent pixels into a single photoluminescent layer rather than maintaining separate side-by-side pixels. This integration simplifies the manufacturing process, reduces alignment precision requirements, and lowers production costs while still achieving full-color display through the photoluminescent conversion of blue light.
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 significantly improves light energy utilization efficiency and viewing angles by allowing almost all red, green, and blue light to pass through without absorption, while simplifying the manufacturing process by reducing alignment complexities and lowering production costs.
Implementation Method 1
a blue light source 10 and a photoluminescent display panel 20... the blue light can be converted into a red light while passing through the green pixel region of the photoluminescent structure
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A photoluminescent display device includes a blue light source (11) and a photoluminescent display panel (20) adjoining the blue light source. The photoluminescent display panel includes a transparent substrate (21), a color filter structure (22) and a photoluminescent structure (23). The color filter structure includes a red pixel region (22R), a green pixel region (22G) and a blue pixel region (22B) arranged adjacent to one another on the transparent substrate. The photoluminescent structure, which is disposed on the color filter structure and is facing toward the blue light source, includes a red light-conversion layer (232) and a green light-conversion layer (231), wherein the red light-conversion layer is disposed on the green light-conversion layer. With this vertically stacked arrangement of the light-conversion layers, the photoluminescent display device can have higher optical energy utilization efficiency and a wider viewing angle, while being easier to be manufactured by relaxing the specification of accurate pixel-level alignment among the light-conversion layers and the color filter structure.