LED Barrier Encapsulant for Uniform Phosphor Distribution

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Solution Overview

Problem

In existing white LED packages, the phosphor is non-uniformly distributed, leading to wide color temperature variations and reduced light extraction efficiency due to precipitation within the encapsulating material.

Innovation Solution

A light emitting device package is designed with a barrier around the LED chip, encapsulating a phosphor-containing material to ensure uniform distribution and improved light extraction efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If phosphor is added to encapsulating material in related art white LED packages, then color conversion is achieved, but phosphor precipitates on the bottom of the LED package over time causing non-uniform distribution and wide color temperature distribution

Engineering Contradiction:

Improvecolor temperature uniformityVSAvoidphosphor distribution uniformity

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The encapsulating material is divided into multiple layers with different phosphor concentrations. The first encapsulating material layer has a first phosphor concentration, while the second encapsulating material layer has a second phosphor concentration that is different from the first. This segmentation prevents phosphor precipitation and maintains uniform distribution over time, resolving the contradiction between reliability and compositional stability.

Inventive Principle:

Principle #1Segmentation

2Quantity of substance

If phosphor distribution area is made relatively greater than LED area, then more light conversion is possible, but phosphor becomes non-uniformly distributed around the LED leading to wide color temperature distribution

Engineering Contradiction:

Improvephosphor amountVSAvoidphosphor distribution uniformity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

Different regions of the encapsulating material have different phosphor concentrations tailored to local requirements. The first encapsulating material layer is positioned at a first location relative to the LED with a first phosphor concentration, while the second encapsulating material layer is positioned at a second location with a second phosphor concentration. This local quality approach ensures uniform phosphor distribution while maintaining adequate phosphor quantity for light conversion.

Inventive Principle:

Principle #3Local quality

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 achieves a more uniform phosphor distribution around the LED chip, narrowing the color temperature range and enhancing light extraction efficiency by preventing phosphor precipitation and optimizing the encapsulating material's surface design.

Implementation Method 1

a yellow phosphor (using phosphors such as yttrium aluminum garnet (YAG) and terbium aluminum garnet (TAG)) may be added to the blue LED

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Implementation Method 2

the phosphor within an encapsulating material may be precipitated on a bottom of the LED package

Methodology Applied

Scientific EffectLight absorption and emission: Absorption (EM radiation)

Data Source

PatentUS8415698B2Light emitting device with encapsulant formed with barriers and light emitting device package having the same

Publication Date: 2013.04.09 SUZHOU LEKIN SEMICON CO LTD

AI summary

Provided are a light emitting device, a light emitting device package, and a lighting system. The light emitting device (LED) comprises an LED chip, a barrier over the LED chip, and an encapsulating material containing a phosphor, wherein the encapsulating material is disposed inside the barrier over the LED chip.