Micro-LED Reflective Element and Diffuser for Light Extraction
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Solution Overview
Problem
Current micro-LED (µ-LED) displays face challenges in achieving high directionality and uniform illumination due to their small size and complex manufacturing processes, leading to issues like the fly screen effect and limited light extraction efficiency, which are critical for augmented reality and automotive applications.
Innovation Solution
The use of a flat carrier substrate with integrated µ-LEDs and a reflective element with a diffuser layer to achieve Lambertian radiation characteristics, combined with photonic structures for beam shaping and light directionality, enhances light extraction and reduces crosstalk between pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If µ-LEDs are used for display applications, then high resolution and small pixel size are achieved, but light extraction efficiency is limited
Solution Approach 1:
A reflective element with diffuser layer is introduced as an intermediary component between the µ-LED and the external environment. The reflective element captures light that would otherwise be lost and redirects it through the diffuser layer, improving light extraction efficiency without affecting the small pixel size and high resolution of the µ-LED display
Solution Approach 2:
The reflective element is positioned beneath the µ-LED in the vertical dimension, utilizing the space below the light-emitting component. This allows light extraction enhancement without increasing the lateral footprint of each pixel, thereby maintaining high display resolution while improving light extraction efficiency
2Measurement precision
If µ-LEDs are used for display applications, then high resolution is achieved, but uniform illumination is difficult to obtain
Solution Approach 1:
The diffuser layer acts as an intermediary optical element that scatters and redistributes light from the µ-LED sources. This creates more uniform illumination across the display while maintaining the high resolution enabled by the small µ-LED pixel size
Solution Approach 2:
The reflective element with diffuser layer is specifically designed and positioned for each pixel or group of pixels, allowing local optimization of light distribution. This ensures uniform illumination across the entire display while maintaining the high resolution characteristics of individual µ-LED pixels
3Volume of moving object
If µ-LEDs are used for augmented reality applications, then small device size is achieved, but fly screen effect becomes visible
Solution Approach 1:
The diffuser layer serves as an intermediary optical element that softens the point-source nature of µ-LED emission. By scattering light before it reaches the user's eye, the diffuser layer reduces the visibility of individual pixels and eliminates the fly screen effect while maintaining the compact device size required for augmented reality applications
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 approach improves light distribution uniformity and directionality, minimizing the fly screen effect and increasing light extraction efficiency, resulting in better image quality and reduced pixel visibility in augmented reality and automotive displays.
Implementation Method 1
The layer stack is provided with a reflective contact on the surface facing away from the substrate. The reflective contact extends isolated from the doped layers along a side surface to the substrate surface.
Implementation Method 2
The use of a flat carrier substrate with integrated µ-LEDs and a reflective element with a diffuser layer to achieve Lambertian radiation characteristics
Implementation Method 3
combined with photonic structures for beam shaping and light directionality
Data Source
AI summary
The invention relates to various aspects of a μ-LED or a μ-LED array for augmented reality or lighting applications, in particular in the automotive field. The μ-LED is characterized by particularly small dimensions in the range of a few μm.