RGB LED Package Layout for High-CRI White Light
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Solution Overview
Problem
Conventional LED packages with multiple LEDs for emitting white light often have a poor color rendering index (CRI) due to peak emissions at specific wavelengths, which limits their ability to faithfully reproduce colors compared to natural light sources.
Innovation Solution
The design incorporates a single undivided reflective cup with both narrowband LEDs and a phosphor-coated blue LED, allowing for improved heat management and flexibility in emission profiles, along with an extended lead frame for enhanced adhesion and heat dissipation, eliminating the need for a dam or partition and simplifying manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multiple narrowband LEDs are used to emit white light, then energy efficiency is improved, but color rendering index (CRI) deteriorates due to peak emissions at specific wavelengths
Solution Approach 1:
The patent combines multiple narrowband LEDs (red, green, blue) with a broadband phosphor-coated LED in a single package. The phosphor material converts a portion of the LED's blue light into a broad spectrum including yellow, red, and green wavelengths, merging the advantages of both narrowband and broadband light sources to achieve high energy efficiency and excellent color rendering simultaneously.
Solution Approach 2:
The invention uses composite phosphor materials with specific emission characteristics (yellow, red, and green components) coated on the blue LED. This composite phosphor layer transforms the narrowband blue light into a composite spectrum that, when combined with the remaining blue light and the emissions from the narrowband LEDs, produces white light with high CRI while maintaining energy efficiency.
2Reliability
If a reflective cup with dam or partition is used to separate phosphor-coated LED from other LEDs, then color rendering is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by positioning the phosphor-coated LED at the center of the reflective cup while placing narrowband LEDs at the periphery. The reflective cup's geometry and the strategic placement of different LED types create localized optical zones that work together to achieve high color rendering without requiring physical partitions or dams, thus maintaining structural simplicity.
3Ease of manufacture
If conventional LED package design is used, then manufacturing is simplified, but heat management deteriorates leading to reliability issues
Solution Approach 1:
The patent makes the reflective cup multi-functional by designing it to serve both as a light-reflecting surface for optimal color rendering and as a heat-dissipating structure. The cup's geometry and material properties enable it to perform dual functions: optical reflection to enhance light extraction and thermal conduction to manage heat from the high-power LEDs, thereby improving reliability without complicating manufacturing.
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
This configuration results in LED packages that produce white light with a higher CRI and improved heat management, enabling more reliable and efficient lighting with enhanced color reproduction and compact package designs.
Implementation Method 1
a white solid state emitter (BSY LED) having a blue emitting LED coated by a phosphor
Implementation Method 2
Light emitted by the LED at a first wavelength may be absorbed by the phosphor, which may responsively emit light at a second wavelength
Implementation Method 3
a single reflective cup... The reflective cup may direct light in an upward direction
Implementation Method 4
The reflective cup may be filled with an encapsulant material 16 which may contain a wavelength conversion material such as a phosphor
Implementation Method 5
A lead frame 56 is provided integral to the housing... arranged to allow for individual control of the LEDs
Implementation Method 6
improved package heat management... extended lead frame for enhanced adhesion and heat dissipation
Data Source
AI summary
LED packages are disclosed capable of emitting a range of colors including white light, while still emitting that can have a high color rendering index (CRI). The LED packages can have a simplified reflective cup arrangement and improved lead frame design. The LED packages according to the present invention comprise one or more LED WITH PHOSPHORs for high CRI lighting applications, along with multiple narrowband emitters (e.g. RGB LEDs), but do not have a dam or partition to segregate the LED WITH PHOSPHOR from the multiple emitters. This results in a LED package that is less complex and easier to manufacture, while still providing the desired flexibility in LED package emissions.