LED Filament with Wavelength Converting Material for Color Temperature Control
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Solution Overview
Problem
Current LED-based lighting solutions lack the ability to effectively control color temperature, limiting their versatility and adaptability to various applications and atmospheres, as they often rely on two light sources that cannot accurately approximate the color of a black body radiator across a wide range.
Innovation Solution
A color controllable LED filament is developed, comprising a carrier with three types of LEDs (blue, green, and red) and a wavelength converting material that absorbs blue light more than green and red light, allowing for the emission of light across a wide range of correlated color temperatures by varying the intensity of each LED type and using a controller to adjust the power supply, thereby altering the color temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two light sources are used in LED filament, then the structure is simple, but the color temperature control range is limited and cannot accurately approximate black body radiator colors
Solution Approach 1:
The LED filament is segmented into three distinct LED types with different peak wavelengths (first type: 400-500nm, second type: 500-570nm, third type: 590-680nm). Each LED type contributes differently to the overall spectrum, enabling precise color temperature control by independently adjusting the intensity of each segment, thus achieving wide color temperature range without excessive complexity
Solution Approach 2:
Different regions of the filament have LEDs with specific wavelength characteristics optimized for their function. The first type LEDs (blue region) are positioned to work with the wavelength converting material, while second and third type LEDs (green and red regions) are positioned to complement the spectrum. This local optimization of wavelength distribution enables accurate black body radiator approximation across different color temperatures
2Illumination intensity
If wavelength converting material is added to convert blue light, then cool white light is enhanced, but the absorption of green and red light increases
Solution Approach 1:
The wavelength converting material is engineered with specific optical parameters: it has a higher absorption coefficient for the first peak wavelength (blue light at 400-500nm) than for the second (green at 500-570nm) and third (red at 590-680nm) peak wavelengths. This parameter optimization ensures efficient blue light conversion to cool white while minimizing energy loss in the green and red regions, maintaining overall luminous efficiency
Solution Approach 2:
The patent employs a composite lighting system combining three different LED types with distinct spectral characteristics and a wavelength converting material. This composite approach allows the system to leverage the high efficiency of blue LEDs with the converting material while supplementing with green and red LEDs to compensate for any absorption losses, achieving a balanced spectrum that approximates black body radiator colors across a wide color temperature range
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
This solution enables the LED filament to emit light with a wide range of correlated color temperatures, from cool white to warm white, allowing for adaptability in different applications and atmospheres, enhancing user flexibility and comfort.
Implementation Method 1
The wavelength converting material has a higher absorption coefficient for the first peak wavelength than for the second peak wavelength and the third peak wavelength. The wavelength converting material has an emission band extending at least between 500 and 650 nm.
Implementation Method 2
For non-converted light, the encapsulant may act as a scattering material which may improve the color mixing of the light emitted by the different LEDs.
Data Source
AI summary
The present disclosure relates to a light-emitting diode (LED) filament (100) comprising a carrier (120) having a first side on which a plurality of LEDs is arranged. The plurality of LEDs comprises a LED of a first type (111) arranged to emit light having a first peak wavelength in the range 400-500 nm, a LED of a second type (112) arranged to emit light having a second peak wavelength in the range 500-570 nm, and a LED of a third type (113) arranged to emit light having a third peak wavelength in the range 590-680 nm. An encapsulant (130) encapsulates at least the LED of the first type, and at least partly the LEDs of the second type and the third type. The encapsulant (130) comprises a wavelength converting material having a higher absorption coefficient for the first peak wavelength than for the second peak wavelength and the third peak wavelength. The wavelength converting material has an emission band extending at least from 500 to 650 nm.