Fresnel Lens Display Structure for Micro-LED Light Extraction
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Solution Overview
Problem
Micro-LED and OLED displays face challenges in maximizing light-emitting efficiency due to total reflection of light emitted by LEDs, which current technologies have not adequately addressed.
Innovation Solution
A display device design incorporating a substrate with light-emitting diodes, an encapsulant, and a Fresnel lens where the Fresnel lens width is 4 to 10 times the width of the light-emitting diode, positioned to overlap and enhance light-emitting efficiency by minimizing refraction and reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional display structure without Fresnel lens is used, then the structure is simple, but light-emitting efficiency is low due to total reflection
Solution Approach 1:
A Fresnel lens is introduced as an intermediary optical element between the light-emitting diode and the external environment. The lens refracts and redirects light rays that would otherwise undergo total internal reflection, converting lost light into useful output and significantly improving light-emitting efficiency
Solution Approach 2:
The Fresnel lens employs curved refractive surfaces with specific radii of curvature (R1 and R2) to control light propagation. The curved geometry enables precise refraction angles that redirect light away from total reflection paths, optimizing light extraction while maintaining a compact form factor
2Loss of energy
If the width of Fresnel lens is increased to improve light extraction, then light-emitting efficiency increases, but the device thickness increases
Solution Approach 1:
The Fresnel lens is segmented into multiple concentric zones or rings with progressively varying refractive angles. This segmentation allows the lens to maintain an extremely thin profile while still providing effective light redirection across the entire aperture, as each segment contributes to light extraction without requiring increased overall thickness
Solution Approach 2:
Instead of increasing thickness to improve light extraction, the solution transitions to optimizing the lateral dimension through an enlarged lens width (4-10 times the LED width). This dimensional shift allows light extraction improvement while maintaining thinness in the thickness dimension
3Productivity
If multiple Fresnel lenses are added to cover multiple LEDs, then overall light-emitting efficiency improves, but device complexity increases
Solution Approach 1:
Multiple Fresnel lenses are merged into a single integrated optical component that simultaneously serves multiple light-emitting diodes. The lens structure is designed with multiple active zones or a continuous refractive surface that covers and optimizes light extraction from several LEDs, reducing the total component count while maintaining improved light-emitting efficiency across all LEDs
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 design significantly improves light-emitting efficiency and maintains a thin thickness, optimizing the alignment and curvature of Fresnel lenses with LEDs to reduce light loss and enhance display performance.
Implementation Method 1
a first Fresnel lens (132). The first Fresnel lens (132) is located on the encapsulant (120) and overlapping with the first light emitting diode (112)
Implementation Method 2
avoid the problem of total reflection of light emitted by the LEDs inside the displays
Data Source
AI summary
A display device includes a substrate, a first light-emitting diode, an encapsulant and a first Fresnel lens. The first light emitting diode is located on the substrate. The encapsulant covers the first light emitting diode. The first Fresnel lens is located on the encapsulant and overlapping with the first light emitting diode. The width of the first Fresnel lens is 4 to 10 times the width of the first light emitting diode.