White Light Source Blue LED Phosphor Spectrum Control
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Solution Overview
Problem
Conventional white light sources using LED elements have a strong blue emission peak, making their emission spectrum significantly different from natural light, which can disrupt the human circadian rhythm and cause adverse effects on the body.
Innovation Solution
The development of white light sources with a specific ratio of minimum to maximum emission intensity in the 450 to 610 nm wavelength region, combined with LED elements and phosphors, to mimic the emission spectrum of natural light, thereby reducing the blue light peak and achieving a predetermined color temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a blue LED element with strong emission peak is used to achieve high luminous flux, then the luminous efficiency is improved, but the emission spectrum deviates significantly from natural light, causing adverse effects on human circadian rhythm
Solution Approach 1:
The patent applies parameter changes by carefully controlling the emission peak wavelength of the blue LED element (440-480 nm) and the emission peak wavelengths of multiple phosphors (460-500 nm, 500-560 nm, 560-650 nm). By adjusting these spectral parameters and their relative intensities, the invention transforms the conventional strong blue peak spectrum into a balanced spectrum that mimics natural light while maintaining high luminous efficiency.
Solution Approach 2:
The patent uses composite materials by combining a blue LED element with multiple types of phosphors (blue phosphor, green phosphor, red phosphor) to create a composite light-emitting system. This composite structure allows the integration of multiple emission characteristics, producing a balanced spectrum that combines the high efficiency of LED with the natural-like spectral distribution of multiple phosphors.
2Object-affected harmful factors
If the emission peak of blue LED element is suppressed to reduce adverse effects, then the harm to human body is reduced, but it becomes difficult to achieve predetermined color temperature due to narrow half value width
Solution Approach 1:
The patent merges multiple light sources with different spectral characteristics: the blue LED element (which provides high efficiency) and multiple phosphors with different emission peaks (which provide spectral balance). By combining these components, the invention achieves both reduced blue light harm and precise color temperature control, as the phosphors fill in the spectral gaps and broaden the overall emission profile.
Solution Approach 2:
The phosphors act as intermediaries that convert the blue LED light into additional wavelengths. The phosphors mediate between the blue LED source and the final white light output, transforming the narrow blue peak into a broader, more natural spectrum while maintaining the ability to control color temperature through phosphor selection and ratios.
3Productivity
If conventional blue LED with strong peak is used, then high luminous flux is achieved, but the emission spectrum is largely different from natural light
Solution Approach 1:
The patent changes the spectral parameters by introducing multiple phosphors with specific emission peak ranges (blue: 460-500 nm, green: 500-560 nm, red: 560-650 nm) to modify the overall emission spectrum. This parameter adjustment transforms the narrow blue peak into a broad, natural-like spectrum while preserving high luminous flux through efficient phosphor conversion.
Solution Approach 2:
The invention creates a composite light-emitting system that combines blue LED material with multiple phosphor materials. This composite approach enables the system to maintain the high luminous flux of LED technology while achieving a spectral composition that closely resembles natural light through the combined emission of multiple phosphors.
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 white light sources effectively suppress the adverse effects on the circadian rhythm by replicating natural light spectra, ensuring a friendly lighting environment for the human body and maintaining a balanced emission spectrum similar to sunlight.
Implementation Method 1
a phosphor layer including a plurality of phosphors for absorbing near ultraviolet emitted by the near ultraviolet LED and for emitting fluorescence having an emission peak in a visible wavelength region
Implementation Method 2
a semiconductor light emitting device which is composed of a combination of a near ultraviolet LED and a phosphor layer
Data Source
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AI summary
A white light source I of an embodiment has color temperature of2600 [K] or more and less than 3200 [K]. The white light source of the embodiment has a ratio of a minimum emission intensity to a maximum emission intensity in a wavelength region of from 450 to 610 [nm] on an emission spectrum of 0.16 or more and le than 0.35.