Light-emitting device with second element filling spectral dip
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Solution Overview
Problem
Light-emitting devices with LEDs and phosphors exhibit a deep dip in their composite emission spectrum, particularly in bluish-white spectra, which deviates from the sunlight emission spectrum, preventing them from achieving a spectrum similar to natural light.
Innovation Solution
Incorporating a second light-emitting element with a peak wavelength positioned between the peak wavelengths defining the deepest dip in the composite emission spectrum of the first light-emitting element and phosphor, and adjusting its wavelength within 2 nm of the dip's bottom, along with a phosphor contained in a sealing material to minimize absorption, to create a shallow dip and align the emission spectrum with sunlight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a light-emitting element with emission wavelength far from phosphor emission spectrum is used to increase excitation light absorption efficiency, then excitation light absorption efficiency is improved, but a deep dip appears in composite emission spectrum
Solution Approach 1:
The patent divides the light-emitting device into multiple light-emitting elements with different emission wavelengths. The first light-emitting element emits at a wavelength far from the phosphor emission spectrum to ensure high excitation absorption efficiency, while the second light-emitting element emits at a wavelength within the phosphor emission spectrum to fill the deep dip. This segmentation allows each element to perform its specialized function without compromise.
Solution Approach 2:
The patent changes the emission wavelength parameter of the light-emitting elements by introducing a second element with a different peak wavelength. The second light-emitting element's peak wavelength is specifically selected to be between the wavelengths defining the deepest dip in the composite spectrum, thereby modifying the overall spectral characteristics to reduce the dip depth while maintaining efficient phosphor excitation.
2Device complexity
If a single light-emitting element is used to simplify device structure, then device complexity is reduced, but emission spectrum cannot closely match sunlight spectrum
Solution Approach 1:
The second light-emitting element serves multiple functions: it fills the deep dip in the composite emission spectrum to improve spectral quality, and simultaneously functions as a transmitter for optical communication. This multi-functionality justifies the added complexity by delivering multiple benefits from a single additional component.
Solution Approach 2:
The patent creates a composite light-emitting system combining multiple light-emitting elements with different spectral characteristics. This composite approach allows the device to achieve a composite emission spectrum that closely matches sunlight by integrating the spectral outputs of individual elements, each contributing specific wavelength ranges.
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 a light-emitting device with an emission spectrum that closely resembles sunlight, reducing the deep dip and enhancing the spectral alignment, while also enabling the second light-emitting element to function as an optical communication transmitter.
Implementation Method 1
a light-emitting device is provided with an LED (Light-Emitting Diode) and a phosphor to emit a white light
Implementation Method 2
a phosphor to emit a white light
Implementation Method 3
a second light-emitting element having a peak wavelength between peak wavelengths of two peaks that define a deepest dip in a composite emission spectrum
Implementation Method 4
the first sealing material has a lower refractive index than the second sealing material
Data Source
AI summary
A light-emitting device includes a first light-emitting element, a phosphor, and a second light-emitting element having a peak wavelength between peak wavelengths of two peaks that define a deepest dip in a composite emission spectrum of the first light-emitting element and the phosphor.