Side-Emitting LED Substrate for Uniform Large-Area Illumination
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) used in display devices often result in non-uniform luminance due to their point-like nature, leading to degraded optical efficiency and difficulty in achieving uniform light distribution across large emission areas without additional optical systems.
Innovation Solution
A light-emitting device with a substrate having a top surface and a side surface, where the light-emitting structure is disposed on the side surface, emitting light uniformly across a larger area through the top surface, and optionally incorporating reflective layers and optical wavelength conversion layers to enhance light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional LED is used as a point light source in display devices, then the device structure remains simple, but non-uniform luminance occurs and optical efficiency is degraded
Solution Approach 1:
The light-emitting structure is moved from the conventional top surface configuration to the side surface of the substrate. This dimensional change allows light to be emitted laterally and then extracted through the top surface, transforming the light propagation path from vertical to lateral-extraction geometry, which enables uniform illumination across large areas without additional optical systems
Solution Approach 2:
Instead of emitting light directly upward from the top surface as in conventional LEDs, this invention inverts the emission approach by placing the light-emitting structure on the side surface and having light travel through the substrate to exit from the top surface, reversing the traditional light extraction geometry to achieve uniform luminance distribution
2Area of stationary object
If the distance between LED and pixel is increased to cover larger area, then the emission area increases, but luminance non-uniformity worsens and optical efficiency degrades
Solution Approach 1:
By changing the light emission geometry from point-source vertical emission to side-surface lateral emission with top-surface extraction, the invention achieves uniform luminance distribution across large emission areas. The lateral emission path through the substrate creates an extended light source that naturally distributes light uniformly without increasing distance from pixels
Solution Approach 2:
The substrate serves multiple functions: it acts as both the mounting platform for the light-emitting structure and as a light guide medium that distributes light uniformly across the top surface. This multi-functionality allows the same component to achieve both large emission area and uniform luminance without requiring additional optical elements
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 solution enables uniform light emission over a large area without the need for additional optical systems, improving luminance and optical efficiency while maintaining a compact design, thus addressing the issue of non-uniformity and enhancing display device performance.
Implementation Method 1
a light-emitting structure disposed on the first side surface of the substrate. The light-emitting structure includes a first-conductivity-type semiconductor layer, a second-conductivity-type semiconductor layer, and an active layer interposed between the first-conductivity-type semiconductor layer and the second-conductivity-type semiconductor layer. The light-emitting structure emits first light having a first peak wavelength.
Data Source
AI summary
A light-emitting device includes a substrate including a top surface and a first side surface, wherein an area of the top surface is larger than an area of the first side surface, and a light-emitting structure on the first side surface of the substrate, the light-emitting structure having a first-conductivity-type semiconductor layer, a second-conductivity-type semiconductor layer, and an active layer between the first-conductivity-type semiconductor layer and the second-conductivity-type semiconductor layer, wherein the light-emitting structure emits a first light having a first peak wavelength, and wherein an emission area of a first light emitted through the top surface of the substrate is larger than an emission area of a first light emitted through the first side surface of the substrate.