μ-LED Array Micro-Projection System Design
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Solution Overview
Problem
Conventional micro-projection systems using digital light processing, liquid crystal projectors, and LCOS devices face challenges in achieving high projection brightness and small volume due to the complexity of optical engines, making it difficult to integrate them into portable electronic devices.
Innovation Solution
A micro-projection system utilizing a μ-LED array as the imaging source, which eliminates the need for a complex optical engine by incorporating a reflection layer, light emitting structure, and light collimation structure, including doped semiconductor layers and photonic crystal structures to achieve efficient light collimation and reduce volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional micro-projection techniques (DLP, LCP, LCOS) are used, then the system can achieve projection function, but the optical engine becomes complex and volume increases
Solution Approach 1:
The patent merges the illumination source and imaging display elements into a single μ-LED array structure. Each μ-LED serves dual functions as both light source and pixel element, eliminating the need for separate illumination and display optical engines. This integration directly reduces system complexity and volume while maintaining projection capability.
Solution Approach 2:
The μ-LED array elements perform multiple functions simultaneously: they generate light, modulate light for image display, and serve as the projection source. This multi-functionality replaces the need for separate illumination sources, liquid crystal layers, and DLP mirrors found in conventional systems, thereby reducing overall system complexity.
2Volume of moving object
If μ-LED array is used as imaging source, then volume is reduced, but optical cross-talk between neighboring μ-LEDs degrades imaging quality
Solution Approach 1:
The patent introduces a microlens array positioned above the μ-LED array as an intermediary optical element. Each microlens corresponds to a specific μ-LED and focuses its light output into a controlled beam. This microlens intermediary prevents light from adjacent μ-LEDs from interfering with each other, thereby eliminating optical cross-talk while preserving the compact volume advantage.
Solution Approach 2:
The microlens array provides localized light control where each microlens is optimized for its corresponding μ-LED element. This local optimization ensures that each pixel's light is precisely directed without affecting neighboring pixels, maintaining high imaging quality through spatially-resolved light management.
3Reliability
If μ-LED array with microlens array is used, then optical cross-talk is reduced, but projection brightness decreases due to light distribution issues
Solution Approach 1:
The patent introduces a projection lens system that collects light from the microlens array and projects it onto a distant screen. This adds a new optical dimension that magnifies the small, high-quality image from the microlens array into a large, bright projection display, thereby recovering and enhancing projection brightness despite the light distribution constraints.
Solution Approach 2:
The patent employs asymmetric optical design where the projection lens system is optimized to collect light preferentially from the microlens array at specific angles. This asymmetric light collection strategy maximizes the utilization of available light from each microlens while maintaining the cross-talk reduction benefits, thereby improving projection brightness without compromising image quality.
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 μ-LED array-based micro-projection system achieves high efficiency and small volume, enhancing imaging quality by minimizing optical cross-talk effects and allowing for the integration of projection systems into portable devices.
Implementation Method 1
each of the μ-LEDs includes a reflection layer, a light emitting structure, and a light collimation structure
Implementation Method 2
each of the μ-LEDs includes a reflection layer, a light emitting structure, and a light collimation structure
Implementation Method 3
the light emitting structure includes a first type doped semiconductor layer, an active layer, and a second type doped semiconductor layer that are stacked sequentially
Implementation Method 4
A micro-projection system utilizing a μ-LED array as the imaging source, which eliminates the need for a complex optical engine by incorporating a reflection layer, light emitting structure, and light collimation structure, including doped semiconductor layers and photonic crystal structures
Data Source
AI summary
A light emitting unit array including a plurality of micro-light emitting diodes (μ-LEDs) is provided. The micro-light emitting diodes are arranged in an array on a substrate, and each of the micro-light emitting diodes includes a reflection layer, a light emitting structure, and a light collimation structure. The light emitting structure is disposed on the reflection layer, and includes a first type doped semiconductor layer, an active layer, and a second type doped semiconductor layer that are stacked sequentially. At least a portion of the first type doped semiconductor layer, the active layer, and the second type doped semiconductor layer are sandwiched between the reflection layer and the light collimation structure.