Planar Light Source Layer Structure for Uniform Light Extraction
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Solution Overview
Problem
Current light-emitting devices for direct-lit backlights in display devices face challenges in enhancing light extraction efficiency and reducing luminance non-uniformity.
Innovation Solution
A light-emitting device structure comprising a wiring board with interconnect layers, light-emitting elements, a light-reflecting member covering lateral surfaces, light-transmitting and light-reflecting layers, a low-refractive-index layer, and a wavelength conversion layer, which improves light extraction efficiency and reduces luminance non-uniformity by effectively diffusing and reflecting light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional light-emitting device structure is used, then the device is simple to manufacture, but light extraction efficiency is insufficient
Solution Approach 1:
The patent segments the light extraction function by introducing multiple discrete layers (light-transmitting layers, light-reflecting layers, low-refractive-index layers) between the light-emitting elements and the extraction surface. Each layer performs a specific optical function, collectively improving light extraction efficiency without requiring complete redesign of the manufacturing process
Solution Approach 2:
The patent employs composite material structures combining different refractive index materials in layered configurations. The light-transmitting layers, light-reflecting layers, and low-refractive-index layers form a composite optical system that enhances light extraction through controlled refraction and reflection at multiple interfaces
2Productivity
If light-emitting elements are arranged in a two-dimensional array, then the device can function as a direct-lit backlight, but luminance non-uniformity occurs
Solution Approach 1:
The patent applies local quality by positioning specific optical layers (light-reflecting layers, low-refractive-index layers) at precise locations between light-emitting elements. These layers are strategically placed to redirect light from high-luminance regions toward low-luminance regions, creating local optical modifications that achieve overall luminance uniformity across the backlight
Solution Approach 2:
The patent introduces intermediary optical layers (light-transmitting layers, light-reflecting layers, low-refractive-index layers) that mediate between the light-emitting elements and the extraction surface. These intermediary layers control light propagation paths and distribute luminance uniformly without requiring direct modification of the light-emitting elements themselves
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 proposed structure enhances light extraction efficiency and achieves more uniform luminance across the emission surface, improving the performance of direct-lit backlights in display devices.
Implementation Method 1
lateral surfaces of a plurality of light-emitting elements on a substrate are covered by a light-reflecting member. The covering of the lateral surfaces of the light-emitting elements by the light-reflecting member can reduce leakage of light from the lateral surfaces of the light-emitting elements, resulting in enhancement of emission luminance
Implementation Method 2
a low-refractive-index layer located between the light-reflecting member and the light-diffusing layer and around each pair of one of the plurality of light-transmitting layers and one of the plurality of light-reflecting layers, the low-refractive-index layer having a refractive index lower than that of the plurality of light-transmitting layers
Implementation Method 3
a light-diffusing layer disposed above the plurality of light-reflecting layers and the light-reflecting member
Data Source
AI summary
A light-emitting device includes a wiring board, a plurality of light-emitting elements disposed on the wiring board, a light-reflecting member covering a lateral surface of each of the plurality of light-emitting elements, a plurality of light-transmitting layers each located above an emission surface of a corresponding one of the plurality of light-emitting elements, a plurality of light-reflecting layers disposed on the plurality of light-transmitting layers, respectively, a light-diffusing layer disposed above the plurality of light-reflecting layers and the light-reflecting member, and a low-refractive-index layer located between the light-reflecting member and the light-diffusing layer, around each pair of one of the plurality of light-transmitting layers and one of the light-reflecting layers, and having a refractive index lower than that of the plurality of light-transmitting layers. Each of the plurality of light-reflecting layer has a width in a cross-sectional view thereof which is equal to or greater than that of a corresponding one of the plurality of light-transmitting layers.