Dual-Blue LED Phosphor Layout for Sunlight-Like White Lighting
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Solution Overview
Problem
Indoor lighting apparatuses with light emitting diodes (LEDs) often have spectral power distributions that differ significantly from sunlight, leading to potential eye damage and disruption of the human circadian rhythm due to excessive blue wavelength exposure, and they suffer from efficiency and manufacturing process issues related to phosphor usage.
Innovation Solution
A light emitting device comprising first and second LED chips with peak wavelengths in the ranges of 400-420 nm and 420-440 nm, respectively, combined with a wavelength converter using blue, green, and red phosphors to achieve a spectral power distribution similar to sunlight, reducing blue wavelength intensity and improving luminous efficacy and processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a blue light emitting diode is used to generate white light, then the luminous efficacy is improved, but the spectral power distribution deviates significantly from sunlight and causes excessive blue wavelength exposure
Solution Approach 1:
The patent segments the blue light source into multiple LED chips with different peak wavelengths (400-420nm, 420-440nm, and 440-460nm). This segmentation allows the system to achieve the desired spectral power distribution by combining multiple wavelength components, reducing excessive blue light exposure while maintaining luminous efficacy.
Solution Approach 2:
The patent applies local quality by using LED chips with different peak wavelengths in specific regions of the spectrum. Each LED chip targets a specific wavelength range, and phosphors are selectively applied to convert specific wavelengths, creating a non-uniform but optimized spectral distribution that mimics sunlight.
2Object-affected harmful factors
If UV or violet light emitting diode with multiple phosphors is used to reduce blue wavelength intensity, then the spectral power distribution approaches sunlight, but the luminous efficacy deteriorates due to excessive wavelength conversion
Solution Approach 1:
Instead of using a single UV or violet LED with multiple phosphors (which causes excessive wavelength conversion), the patent inverts the approach by using multiple blue LED chips with different peak wavelengths and selective phosphors. This reduces the total wavelength conversion required while achieving the desired spectral distribution.
Solution Approach 2:
The patent applies partial wavelength conversion by selectively converting only specific wavelength ranges. Not all LED light is converted to phosphor light, which reduces the efficiency loss associated with excessive wavelength conversion while still achieving the target spectral power distribution.
3Illumination intensity
If blue phosphor amount is increased to reflect more blue light, then the blue wavelength intensity is improved, but the wavelength conversion efficiency deteriorates
Solution Approach 1:
The patent segments the blue light generation into multiple LED chips with different peak wavelengths. This eliminates the need to increase blue phosphor amount, as the blue light is generated directly by the LED chips themselves, maintaining wavelength conversion efficiency while achieving the desired blue light intensity.
4Object-affected harmful factors
If multiple phosphors are used for wavelength conversion, then the spectral power distribution is improved, but the manufacturing processability deteriorates due to increased viscosity
Solution Approach 1:
The patent segments the phosphor application into separate layers for different phosphors (yellow phosphor layer, red phosphor layer). This segmentation reduces the total phosphor concentration in any single layer, lowering viscosity and improving manufacturability while still achieving the desired spectral power distribution through combined effect.
Solution Approach 2:
The patent transitions from mixing multiple phosphors in a single layer to applying them in separate vertical layers. This dimensional change from horizontal mixing to vertical stacking reduces inter-phosphor interactions that increase viscosity, while maintaining the combined spectral effect.
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 prevents eye damage, maintains a spectral power distribution close to sunlight, enhances luminous efficacy, and improves manufacturing reliability by reducing the need for excessive phosphor usage and viscosity issues, while maintaining high color rendering and fidelity indices.
Implementation Method 1
a first light emitting diode chip emitting light having a first peak wavelength in the range of 400 nm to 420 nm; a second light emitting diode chip emitting light having a second peak wavelength in the range of 420 nm to 440 nm
Implementation Method 2
a wavelength converter covering the first and second light emitting diode chips, the wavelength converter including: a blue phosphor having a peak wavelength in the range of 450 nm to 500 nm; a green phosphor having a peak wavelength in the range of 500 nm to 600 nm; and a red phosphor having a peak wavelength in the range of 600 nm to 650 nm
Data Source
AI summary
A light emitting device is adapted to realize white light and includes a first light emitting diode chip emitting light having a first peak wavelength in the range of 400 nm to 420 nm, a second light emitting diode chip emitting light having a second peak wavelength in the range of 420 nm to 440 nm, and a wavelength converter covering the first and second light emitting diode chips. The wavelength converter including a blue phosphor, a green phosphor, and a red phosphor. When a maximum value of a spectral power distribution of the light emitting device or a maximum of a reference spectral power distribution of black body radiation is 100%, a difference between the spectral power distribution of the light emitting device and the reference spectral power distribution is less than 20% at each wavelength in the wavelength range of 440 nm to 640 nm.