LED Package with Dome Cover and Phosphor for High CRI
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Solution Overview
Problem
Light emitting diode (LED) packages face challenges in light output intensity, ruggedness, complexity, operating lifetime, plug-in capability, and spectral light output quality, particularly in achieving high color rendering index (CRI) values for white illumination.
Innovation Solution
A light emitting package design featuring a printed circuit board with light emitting dice or chips, a light transmissive cover, and an encapsulant, where the package includes electrical terminals for power connection and a phosphor composition for wavelength conversion, optimized for improved light extraction and color rendering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bonding of the dice to lead frames is used, then light emitting packages can be produced, but the packages become relatively fragile
Solution Approach 1:
The patent combines the light emitting die, phosphor, and encapsulant into a single integrated package structure that is directly mounted to the lead frame, eliminating the need for separate bonding steps and reducing structural complexity, which improves ruggedness while maintaining electrical connection integrity
2Illumination intensity
If multiple chip packages are used, then light output intensity can be increased, but device complexity increases
Solution Approach 1:
The patent segments the light emitting function into multiple discrete dice that can be individually mounted on the lead frame, allowing increased light output through multiple sources while maintaining manageable package complexity through modular assembly and standardized mounting procedures
3Illumination intensity
If phosphor wavelength conversion is used, then white light can be generated, but operating lifetime decreases due to encapsulant degradation
Solution Approach 1:
The patent introduces a reflective layer as an intermediary between the light emitting die and the encapsulant, which redirects light paths to reduce UV exposure to the encapsulant material, thereby slowing degradation and extending operating lifetime while maintaining white light generation through phosphor conversion
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 enhances light output intensity, ruggedness, and spectral quality, enabling high CRI values for white light, making the LED packages more suitable for illumination applications and compatible with existing lighting fixtures.
Implementation Method 1
A first phosphor composition comprising a first host material and a first dopant material is disposed on an inner surface of the light-transmissive cover. The first phosphor composition has a first Stokes shift. A second phosphor composition comprising a second host material and a second dopant material is disposed on the inner surface of the light-transmissive cover. The second phosphor composition has a second Stokes shift.
Data Source
AI summary
In a lighting package, a printed circuit board supports at least one light emitting die. A light transmissive cover is disposed over the at least one light emitting die. A phosphor is disposed on or inside of the light transmissive dome-shaped cover. The phosphor outputs converted light responsive to irradiation by the at least one light emitting die. An encapsulant substantially fills an interior volume defined by the light-transmissive cover and the printed circuit board.