LED Package with Phosphor Layer for Color Stability
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Solution Overview
Problem
GaN-based LED technologies face challenges in achieving stable color coordinates and high color reproduction due to temperature variations and the need for multiple light emitting device chips, leading to increased complexity and cost in driving circuits.
Innovation Solution
A light emitting device package utilizing two light emitting device chips of different colors, such as green and blue, with a phosphor layer to produce white light, allowing for adjustable color temperature and reduced number of drivers, thereby simplifying the driving circuit and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple light emitting device chips of different colors are used to achieve high color reproduction, then color reproduction range is improved, but device complexity increases due to multiple drivers required
Solution Approach 1:
The patent combines multiple light emitting device chips (blue, green, red) into a single package body with shared electrical connections. The chips are arranged in a matrix pattern and share common anode or cathode lines, reducing the number of independent driver circuits needed. This merging approach maintains full color reproduction capability while simplifying the driving circuit architecture.
Solution Approach 2:
The package body serves multiple functions: it provides mechanical support for multiple chips, acts as a heat sink, and incorporates shared electrical routing that can address multiple chips simultaneously. The universal design allows the same package structure to accommodate different chip combinations (RGB, WBG, etc.) without requiring separate driver circuits for each chip type.
2Stability of the object's composition
If multiple light emitting device chips are used to achieve stable color coordinates, then color stability is improved, but manufacturing cost increases
Solution Approach 1:
The patent segments the light emitting devices into discrete chips (blue, green, red or blue, green, white) that can be independently manufactured and then assembled in a standardized package. This segmentation allows each chip type to be optimized separately for color stability while the standardized package and shared driving circuitry reduce overall manufacturing complexity and cost.
Solution Approach 2:
The patent utilizes different material compositions and band gap parameters in the semiconductor chips to achieve stable color coordinates. By selecting specific material systems (GaN-based for blue/green, AlInGaP for red) with well-characterized optical properties, the invention achieves color stability through inherent material properties rather than complex control mechanisms, thereby reducing manufacturing costs.
3Adaptability or versatility
If phosphor layer is added to convert light colors, then color temperature adjustability is improved, but light extraction efficiency decreases
Solution Approach 1:
The patent applies phosphor materials selectively in specific locations within the package, such as coating phosphor on the package body surface or positioning phosphor particles near specific LED chips. This localized phosphor application allows color temperature adjustment for specific wavelength ranges while minimizing interference with direct light extraction from the high-efficiency blue or green LED chips.
Solution Approach 2:
The phosphor layer acts as an intermediary that converts excess high-energy blue light into longer wavelength green or red light, thereby adjusting the overall color temperature of the emitted light. By positioning the phosphor as an intermediate layer between the LED chips and the external environment, the system achieves color temperature control while maintaining high overall light extraction efficiency through the synergistic combination of direct LED emission and phosphor-converted light.
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 stable color temperature and high color reproduction with a reduced number of drivers, enhancing light emitting efficiency and cost-effectiveness while maintaining a high color reproduction range comparable to multi-chip systems.
Implementation Method 1
a phosphor layer formed over the protective layer
Implementation Method 2
A phosphor layer associated with each light emitting device is formed over at least a portion of the associated light emitting device
Data Source
AI summary
In one embodiment, the light emitting device package includes a package body, electrodes attached to the package body, and at least two light emitting devices electrically connected to the electrodes. Each light emitting device emits light of a different color from the other light emitting devices. A protective layer is formed over the at least two light emitting devices, and a phosphor layer formed over the protective layer. Other embodiments include other structures such a individual phosphor layers on each light emitting device. And, a light apparatus including a package may include a single driver driving the light emitting devices of the package.