Phosphor-Converted LED Signal Light for High-Temperature Stability
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Solution Overview
Problem
Existing yellow LED signal lights exhibit poor energy efficiency due to high light degradation at extreme temperatures, leading to increased material and energy costs, reduced signal light life, and safety risks due to inadequate light intensity.
Innovation Solution
The use of high-efficiency LEDs, such as those made from indium gallium nitride (InGaN), combined with phosphors and filters, to maintain light output and intensity across varying temperatures, with specific chromaticity coordinates and filter cutoff points optimizing light transmission and color consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional yellow LEDs are used in signal lights, then the device can be manufactured with conventional components, but the energy efficiency deteriorates at high temperatures due to light degradation
Solution Approach 1:
The patent changes the material parameters of the LED by using InGaN (indium gallium nitride) instead of traditional yellow LED materials. This parameter change enables the LED to maintain high efficiency at high temperatures by fundamentally altering the semiconductor bandgap and thermal characteristics, thereby resolving the contradiction between energy efficiency and temperature stability.
Solution Approach 2:
The patent employs composite material structure by combining InGaN with phosphor materials (such as yellow phosphor with peak wavelength 570-590nm) to create a phosphor-converted LED system. This composite approach allows the LED to leverage the thermal stability of InGaN while using phosphor to adjust the output spectrum, achieving both energy efficiency and reliable light output at high temperatures.
2Loss of energy
If LEDs with improved high-temperature efficiency are used, then energy efficiency and light output stability improve, but the device complexity increases due to additional components
Solution Approach 1:
The patent merges the functions of the pump LED and phosphor conversion layer into a single integrated light-emitting component. By combining the blue/violet pump source with yellow phosphor in close proximity, the system achieves yellow light emission while maintaining a compact structure that does not significantly increase device complexity despite the improved efficiency requirements.
3Stability of the object's composition
If phosphor converted LEDs with specific wavelengths are used, then color consistency and chromaticity control improve, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for the phosphor material (peak wavelength 570-590nm) and pump LED (peak wavelength 430-470nm) to achieve consistent yellow light output. By establishing these parameter specifications, the patent balances color consistency requirements with achievable manufacturing tolerances, ensuring reliable chromaticity control without excessive precision demands.
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 results in improved energy efficiency, reduced light degradation, and extended signal light life, ensuring consistent and safe light intensity across different environmental conditions.
Implementation Method 1
The at least one or more second type of LEDs includes a pump, a phosphor and a filter having a cutoff point less than or equal to 540 nanometers (nm). The at least one or more second type of LEDs also has a pump peak wavelength less than or equal to 430 nm and has a phosphor with a peak wavelength greater than 575 nm.
Implementation Method 2
The at least one or more second type of LEDs includes a pump, a phosphor and a filter having a cutoff point less than or equal to 540 nanometers (nm).
Data Source
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AI summary
An improved signal light and method for making an improved signal light is disclosed. For example, the improved signal light includes a housing, at least one outer lens and at least one or more second type of light emitting diodes (LEDs) deployed in the housing. The at least one or more second type of LEDs includes a pump, a phosphor and a filter having a cutoff point less than or equal to 540 nanometers (nm). The at least one or more second type of LEDs also has a pump peak wavelength less than or equal to 430 nm and has a phosphor with a peak wavelength greater than 575 nm.