LED Illumination Device with Phosphor-Coated Mixing Cavity
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Solution Overview
Problem
Current LED-based illumination devices face limitations in light output, color quality, and cost due to temperature constraints, color point instability, and the need for complex color control electronics, leading to inefficiencies and high expenses.
Innovation Solution
A light emitting device design featuring a plurality of LEDs within a light mixing cavity with beveled sidewalls, coated with diffusing materials and phosphors, and strategically positioned to enhance light mixing and heat dissipation, allowing for improved color rendering and reduced costs through optimized phosphor placement and heat management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LED chips operate at higher temperatures to increase light output, then illumination intensity improves, but LED chip lifetime deteriorates
Solution Approach 1:
The illumination device divides the light generation function across multiple LED chips arranged in a circular pattern, allowing each chip to operate at lower temperatures while collectively providing sufficient light output. This segmentation distributes thermal load and extends individual chip lifetime.
Solution Approach 2:
A heat sink is introduced as an intermediary thermal management component between the LED chips and the environment. The heat sink actively removes heat from the LED chips, enabling them to operate at lower temperatures without sacrificing light output, thus extending their operational lifetime.
2Illumination intensity
If multiple phosphors are used to improve color rendering, then color quality improves, but device complexity increases
Solution Approach 1:
Multiple phosphor materials are combined in a single integrated coating layer on the interior surface of the housing, rather than using separate phosphor conversion systems for each color. This merging approach achieves improved color rendering while reducing structural and electronic complexity.
Solution Approach 2:
The patent uses phosphors that change color when excited by LED light to transform the spectral output. By selecting phosphors with appropriate emission wavelengths, the system achieves excellent color rendering without requiring complex electronic color control mechanisms.
3Duration of action of stationary object
If heat dissipation capacity is increased to maintain LED temperature, then LED lifetime improves, but device size increases
Solution Approach 1:
The heat sink is designed with a circular cross-section that matches the circular arrangement of LED chips, creating an efficient thermal conduction path. This curved geometry allows compact heat dissipation with minimal device volume, maintaining LED lifetime without excessive size increase.
Solution Approach 2:
The heat sink provides enhanced thermal management specifically at the LED chip locations where heat generation is highest, rather than uniformly distributing heat dissipation throughout the entire device. This localized approach extends LED lifetime while minimizing overall device size.
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, stability, and color quality while reducing costs by leveraging phosphor placement and heat management to improve LED performance and efficiency.
Implementation Method 1
The sidewalls may be coated with a diffusing material and/or covered with one or more phosphors
Implementation Method 2
The reflective sidewalls may be coated with a diffusing material and/or covered with one or more phosphors
Implementation Method 3
The temperature of the LED chip is determined by the cooling capacity in the system
Data Source
AI summary
A light emitting device is produced using a plurality of light emitting diodes within a light mixing cavity formed by surrounding sidewalls. The sidewalls may be integrally formed as part of a surrounding heat sink or alternatively may be an insert into a cavity within a heat sink. The reflective sidewalls may be coated with a diffusing material and/or covered with one or more phosphors. Multiple phosphors are located at different locations of the cavity, e.g., on the sidewalls, a window covering the output port, or on a reflector attached to the bottom of the cavity. The light emitting diodes may be positioned rotationally symmetrically around the optical axis on a board.