Micro LED Pixel Optics for Screen Door Effect Reduction
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Solution Overview
Problem
Optoelectronic light emitting devices with micro LEDs suffer from the 'screen door effect' due to significant differences in illumination between spot-illuminated and dark areas, particularly noticeable at low viewing distances and large pixel pitches, which complicates manufacturing with additional optical components.
Innovation Solution
An optoelectronic light emitting device design featuring a transparent or translucent carrier substrate with a semiconductor light emitting arrangement and a backscattering surface element, where the main radiation direction of the micro LED is directed onto the backscattering surface, using a beam shaping element to achieve homogeneous large-area illumination, reducing the depth and complexity of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If additional optical components (diffusers, beam expanders, light guides) are added to reduce the screen door effect, then homogeneous illumination is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple optical functions (diffusion, beam expansion, light guiding) into a single integrated light guide structure. This light guide element simultaneously performs all three functions that would traditionally require separate components, thereby achieving homogeneous illumination while reducing device complexity and the number of individually handled components per pixel
Solution Approach 2:
The light guide structure is designed as a multi-functional element that serves as a diffuser, beam expander, and light guide all at once. This universal component replaces what would traditionally require multiple specialized optical elements, simplifying the overall device architecture while maintaining the desired illumination homogeneity
2Illumination intensity
If additional optical components are positioned separately to reduce the screen door effect, then pixel illumination is improved, but manufacturing complexity increases
Solution Approach 1:
By integrating diffuser, beam expander, and light guide functions into a single component, the patent eliminates the need for separate positioning and assembly of multiple optical elements. This integration dramatically simplifies the manufacturing process, as fewer components need to be handled, positioned, and aligned individually during assembly
3Use of energy by moving object
If micro LEDs with small-area active layers are used, then energy efficiency is improved, but screen door effect worsens
Solution Approach 1:
The light guide structure transforms the spatial distribution of light by expanding the beam in lateral dimensions. The micro LED emits light in a confined area, but the light guide expands this illumination laterally across the entire pixel area, effectively converting a point-source emission into a area-source illumination without requiring a larger LED active layer, thus maintaining energy efficiency while eliminating the screen door effect
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 design minimizes the screen door effect by providing a homogeneous and large-area illumination, reducing the visibility of shadows and complexity in manufacturing, while maintaining a small overall depth and using fewer components per pixel.
Implementation Method 1
a main radiation direction of the semiconductor light emitting arrangement is directed onto a backscattering surface element arranged behind the transparent or translucent carrier substrate in viewing direction
Data Source
AI summary
An optoelectronic light emitting device includes a pixel with a transparent or translucent carrier substrate, on which a semiconductor light emitting arrangement with at least one micro LED is arranged. The micro LED extends over a partial area of the pixel. The main radiation direction of the semiconductor light emitting arrangement is directed onto a backscattering surface element arranged behind the transparent carrier substrate in viewing direction. The semiconductor light emitting arrangement includes a beam shaping element.