Convex Resin LED Illumination for Thin Remote Phosphor
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Solution Overview
Problem
The 'remote phosphor structure' for liquid crystal displays has inefficient light extraction and difficulty in reducing thickness due to the separation of the LED and phosphor-containing structure.
Innovation Solution
A light-emitting structure with a blue light-emitting element embedded in a transparent resin with a convex surface, a substrate, and a phosphor sheet spaced from the substrate, which improves light extraction efficiency and reduces thickness by minimizing the gap between the substrate and the phosphor sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the LED and phosphor-containing resin are separated to reduce heat conduction, then phosphor wavelength conversion efficiency is improved, but light extraction efficiency deteriorates
Solution Approach 1:
A transparent resin with a convex surface is introduced as an intermediary between the blue LED and the phosphor-containing resin. This mediator broadens the light distribution and improves light extraction efficiency while the separate placement of phosphor maintains wavelength conversion efficiency by reducing heat conduction.
Solution Approach 2:
The transparent resin is formed with a convex surface shape that has a specific curvature radius. This curved surface broadens the light distribution from the LED, improving light extraction efficiency without requiring direct contact between LED and phosphor.
2Loss of energy
If the LED and phosphor-containing structure are separated, then heat conduction to phosphor is reduced, but device thickness increases
Solution Approach 1:
The curvature radius of the convex surface is optimized within a specific range (0.5mm to 2.0mm) to achieve the best balance between light extraction efficiency and device thickness. This parameter optimization allows thin device design while maintaining performance.
Solution Approach 2:
The transparent resin with convex surface is placed locally at specific positions around the LED, providing targeted light distribution improvement without requiring uniform separation across the entire device, thus maintaining thin profile.
3Illumination intensity
If three color LEDs (R, G, B) are arranged to produce white light, then motion picture properties are improved, but manufacturing cost increases
Solution Approach 1:
Instead of using three separate color LEDs, a blue LED is used in combination with a phosphor-containing resin that converts blue light to other wavelengths. This color conversion approach achieves full-spectrum white light with better motion picture properties while significantly reducing manufacturing cost and complexity.
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 convex surface shape of the transparent resin and the light-scattering effect of the phosphor sheet enhance light extraction efficiency and allow for a thinner remote phosphor structure, improving brightness and reducing thickness in liquid crystal display devices.
Implementation Method 1
suppress light confinement effect of blue light caused by total reflection of transparent resin by convex surface shape of the transparent resin
Implementation Method 2
a phosphor sheet disposed at a position spaced from the substrate and containing phosphor particles that obtain white light from blue light of the blue light-emitting element
Implementation Method 3
owing to the light-radiation distribution broadened by the convex surface shape of the transparent resin and the light-scattering effect of the phosphor sheet containing phosphor particles
Implementation Method 4
since the LED and the phosphor-containing resin are disposed so as not to contact with each other, the heat generated at the same time of LED light emission is hardly conducted to the phosphor such that the temperature of the phosphor hardly increases
Data Source
AI summary
Provided is an illumination device that can be made thin and increases the efficiency of extracting light to the outside. The present invention is provided with: light-emitting structures wherein a blue light-emitting element is embedded in a transparent resin having a convex surface shape; a substrate wherein the light-emitting structures are disposed two-dimensionally; a diffuser plate that diffuses the blue light of the blue light-emitting elements; and a fluorescent sheet that is disposed spaced from the substrate and that contains a particulate fluorescent body that obtains a white light from the blue light of the blue light-emitting elements.