LED Microlens Structure for Light Extraction and Collimation
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Solution Overview
Problem
Light-emitting diode (LED) devices face inefficiencies in light emission and collimation due to internal reflections and scattering, which reduce the effectiveness of light propagation and extraction in display applications.
Innovation Solution
Incorporating microlenses with a larger front surface area than back surface area over LEDs to enhance light collimation and reduce internal reflections, specifically using an inverted frusto-pyramidal shape to improve light propagation and extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional LED structures are used, then device simplicity is maintained, but light extraction efficiency and collimation are reduced due to internal reflections and scattering
Solution Approach 1:
The patent introduces microlenses as intermediary optical elements positioned between the LED light source and the external environment. These microlenses serve as mediators that capture internally reflected and scattered light, refract it through controlled pathways, and redirect it toward external emission. This intermediary structure resolves the contradiction by adding a functional layer that improves light extraction efficiency without fundamentally redesigning the LED core structure.
Solution Approach 2:
The patent employs curved spherical surfaces for the microlenses, utilizing spherical geometry to optimize light refraction and collimation. The spherical shape enables controlled bending of light rays through refraction, converting divergent internally reflected light into more collimated external emission. This curvature-based approach improves light extraction while maintaining a relatively simple lens structure that can be integrated into existing LED devices.
2Illumination intensity
If microlenses with larger front surface area are used, then light collimation and emission intensity are improved, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes specific geometric parameters of the microlenses, including the front surface area, back surface area, and sidewall angles, to achieve improved light collimation and emission intensity. By carefully controlling these parameters within specific ranges, the design balances optical performance with manufacturability. The parameter optimization allows for larger front surface areas that enhance light gathering and collimation capabilities while maintaining fabrication feasibility through defined geometric constraints.
Solution Approach 2:
The patent employs asymmetric microlens geometry where the front surface area is deliberately made larger than the back surface area, creating an inverted frusto-pyramidal or asymmetric spherical shape. This asymmetric design optimizes light collimation by providing a larger aperture for light extraction while maintaining a smaller base for LED integration. The asymmetry resolves the contradiction by optimizing the light-emitting geometry without requiring perfectly symmetric precision throughout the entire lens structure.
3Productivity
If microlenses are added to LED devices, then light propagation effectiveness is improved, but device complexity and fabrication difficulty increase
Solution Approach 1:
The patent divides the optical enhancement function into separate microlens elements that can be independently fabricated and then integrated with the LED device. This segmentation allows the microlenses to be manufactured using specialized techniques while the LED core remains unchanged. The segmented approach improves light propagation effectiveness by adding dedicated optical elements without requiring complex integration processes that would significantly increase overall fabrication difficulty.
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 use of microlenses with a larger front surface area enhances light collimation and reduces internal reflections, leading to improved light emission intensity and directionality, thereby increasing the effectiveness of LED devices in display applications.
Implementation Method 1
microlenses with a larger front surface area than back surface area over LEDs to enhance light collimation and reduce internal reflections
Implementation Method 2
inefficiencies in light emission and collimation due to internal reflections and scattering
Data Source
AI summary
A light-emitting device includes a backplane, light-emitting diodes (LEDs) located over a front side of the backplane, and microlenses respectively disposed over the LEDs. Each microlens includes a back surface having a first surface area and configured to receive light emitted from a corresponding LED, an opposing front surface having a second surface area and configured to emit the received light, and at least one sidewall extending from the front surface to the back surface. The second surface area is greater than the first surface area.