Light Emitting Device Spectral Dip Reduction
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Solution Overview
Problem
Light emitting devices with bluish white spectra, characterized by high color temperature, exhibit a deep dip between the emission spectra of the light emitting elements and phosphors, making it difficult to achieve an emission spectrum similar to sunlight.
Innovation Solution
A light emitting device comprising multiple light emitting elements and a phosphor layer, where the second light emitting element's emission spectrum is strategically positioned to reduce the depth of the dip in the synthesized emission spectrum, with the phosphor layer distributing light at longer wavelengths and the second light emitting element's peak wavelength located between the defining peak wavelengths of the dip, and the phosphor layers having varying densities and compositions to optimize wavelength conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single light emitting element and phosphor are used to create white light, then the device structure is simple, but the emission spectrum has a deep dip and cannot closely resemble sunlight
Solution Approach 1:
The patent divides the light emitting device into multiple light emitting elements (first light emitting element with first wavelength, second light emitting element with second wavelength) that emit different wavelengths of light. This segmentation allows the device to produce a more complete emission spectrum by combining multiple spectral components, thereby reducing the deep dip characteristic of single-element devices and achieving better sunlight-like spectral quality.
2Use of energy by moving object
If the emission wavelength of the light emitting element is separated from the phosphor emission spectrum to increase excitation efficiency, then excitation light absorbing efficiency improves, but the synthesized emission spectrum develops a deep dip that prevents it from resembling sunlight
Solution Approach 1:
The patent employs multiple light emitting elements with different emission wavelengths (first wavelength and second wavelength) to excite the phosphor. By changing the wavelength parameters of the excitation sources, the device achieves both high excitation efficiency (each wavelength optimized for phosphor absorption) and a complete synthesized emission spectrum (multiple wavelengths filling in the spectral gaps), thereby resolving the contradiction between excitation efficiency and spectral quality.
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 an emission spectrum that closely resembles sunlight by reducing the depth of the dip, thereby enhancing the spectral similarity to natural light.
Implementation Method 1
a phosphor layer including a plurality of phosphors, which is disposed on the first and second light emitting elements, wherein the phosphor layer receives the first and second emitted light and outputs a plurality of emitted light based on the plurality of phosphors
Data Source
AI summary
A light emitting device includes a first light emitting element that outputs a first emitted light having a first peak wavelength, a second light emitting element that outputs a second emitted light having a second peak wavelength, and a phosphor layer including a plurality of phosphors, which is disposed on the first and second light emitting elements. The phosphor layer receives the first and second emitted light and outputs a plurality of emitted light based on the plurality of phosphors so as to form a first synthesized emission spectrum. The second light emitting element includes an emission spectrum to reduce a depth of a deepest dip of at least one dip in a second synthesized emission spectrum that is formed by removing an emission spectrum of the second emitted light from the first synthesized emission spectrum.