Micro LED Reflective Layer Layout for Phosphor Light Extraction
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Solution Overview
Problem
Display devices using micro LEDs face challenges in achieving high light extraction efficiency due to the isotropic light emission of phosphor materials, which can reduce the light output on the display surface.
Innovation Solution
A display device configuration featuring a first substrate with pixels, a light emitting element, a phosphor layer covering the light emitting element, a first reflective layer facing the side surface of the light emitting element, and a second reflective layer positioned farther away from the first substrate, separated from the first reflective layer, to enhance light extraction efficiency by increasing the number of reflections and directing light towards the normal direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a phosphor layer is used to convert blue light to red or green light, then color display is achieved, but light extraction efficiency decreases due to isotropic light emission
Solution Approach 1:
The patent introduces a vertical dimension to light control by stacking multiple reflective layers at different heights and positions. The first reflective layer is positioned near the light emitting element while the second reflective layer is positioned farther away in the vertical direction, creating a three-dimensional light management structure that redirects isotropically emitted light toward the display surface.
Solution Approach 2:
The reflective layers act as intermediary elements between the isotropically emitting phosphor layer and the display surface. These layers intercept light traveling in various directions and redirect it toward the normal direction, effectively mediating the light path without requiring changes to the phosphor material itself.
2Illumination intensity
If reflective layers are added to improve light extraction, then light intensity increases, but device structure becomes more complex
Solution Approach 1:
The light management function is segmented into multiple reflective layers positioned at different locations. The first reflective layer handles light redirection near the source, while the second reflective layer provides additional redirection farther from the source. This segmentation allows each layer to perform a specific function in the light path, improving overall efficiency while maintaining modular simplicity.
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 configuration significantly improves light extraction efficiency by increasing the number of reflections and directing light towards the normal direction, resulting in higher light intensity on the display surface.
Implementation Method 1
a phosphor layer covering at least an upper surface of the light emitting element
Implementation Method 2
a first reflective layer facing a side surface of the light emitting element; and a second reflective layer provided to a side surface of the phosphor layer
Data Source
AI summary
A display device comprising: a first substrate; a plurality of pixels provided to the first substrate; a light emitting element provided to each of the pixels; a phosphor layer covering at least an upper surface of the light emitting element; a first reflective layer facing a side surface of the light emitting element; and a second reflective layer provided to a side surface of the phosphor layer, separated from the first reflective layer in a normal direction of the first substrate, and disposed farther away from the first substrate than the first reflective layer.