Curved Encapsulation Layer for Mini-LED Backlight Light Extraction
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Solution Overview
Problem
In existing mini-LED backlight systems, total internal reflection at the air interface of the encapsulation layer leads to significant light energy loss and reduced light output ratio due to the low reflectivity of the circuit board's white lacquer compared to reflection sheets.
Innovation Solution
A backlight module design featuring a circuit board with light emitting elements covered by a first encapsulation layer having a curved surface and a refractive index less than 1.2, and a second encapsulation layer with a refractive index greater than 1.5, which reduces total reflection and enhances light output by diffusing light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a planar encapsulation layer is used, then the structure is simple and easy to manufacture, but total internal reflection occurs at the light output surface causing light energy loss
Solution Approach 1:
The patent applies curvature to the encapsulation layer by forming a convex lens shape on the light output surface. This curved surface design changes the angle of light incidence, preventing total internal reflection and improving light extraction efficiency. The specific implementation uses a convex lens with a curvature radius of 0.5-2mm, which effectively redirects light that would otherwise be trapped by total internal reflection.
Solution Approach 2:
The patent changes the refractive index parameter of the encapsulation layer material to optimize light extraction. By selecting materials with specific refractive indices (1.4-1.7) and controlling the thickness of the encapsulation layer (0.1-0.5mm), the design achieves better light output while managing total internal reflection effects.
2Illumination intensity
If the refractive index of the encapsulation layer is high, then light extraction is improved, but total internal reflection increases causing energy loss
Solution Approach 1:
The patent optimizes the refractive index parameter of the encapsulation layer material to balance light extraction and total internal reflection. By selecting materials with refractive indices in the range of 1.4-1.7 (such as epoxy resin, silicone resin, or acrylic resin), the design achieves improved light output while controlling energy loss from total internal reflection.
3Loss of energy
If a reflection sheet is used to improve reflectivity, then light reflection is enhanced, but the overall structure becomes more complex and costly
Solution Approach 1:
The patent removes the reflection sheet component from the traditional backlight structure. Instead of using a separate reflection sheet layer, the design integrates light management functions directly into the encapsulation layer through its curved surface geometry and optimized refractive index, thereby simplifying the overall structure and manufacturing process.
Solution Approach 2:
The encapsulation layer is designed to perform multiple functions simultaneously: it provides structural support, protects the LED, manages light extraction through its curved surface, and controls reflection through its refractive index. This multi-functionality eliminates the need for separate reflection sheets and other light management components.
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 effectively prevents total reflection at the light output surface, improving the light output ratio and reducing energy loss, while also allowing for a potential reduction in the number of light emitting elements and manufacturing costs.
Implementation Method 1
a refractive index of the first encapsulation layer is less than 1.2
Implementation Method 2
light is easily to occur a totally reflection at a light output surface of an encapsulation layer
Implementation Method 3
a second encapsulation layer with a refractive index greater than 1.5, which reduces total reflection and enhances light output by diffusing light effectively
Data Source
AI summary
An embodiment of the present invention discloses a backlight module and a display device. The backlight module includes a circuit board. A side surface of the circuit board is provided with a plurality of light emitting elements spaced apart from each other. A light output surface of at least one of the light emitting elements is covered with a first encapsulation layer. A side surface of the first encapsulation layer away from the at least one light emitting elements is a curved surface.