Multi-Phosphor LED Color Temperature Control via Segmentation
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Solution Overview
Problem
Conventional light emitting devices using blue and red LEDs with phosphors struggle to achieve a wide variable range of color temperature and smooth variation, limiting their ability to produce illumination light with high color temperature effectively.
Innovation Solution
A light emitting device incorporating multiple solid state light emitting elements with different peak wavelengths and a wavelength converter containing three types of phosphors, where the phosphors are excited by light from these elements to cover the intermediate wavelength range, allowing for control of color temperature through varying the turn-on power of the LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple phosphors are excited by blue LED light to compensate intermediate wavelength range, then color rendering property is improved, but color temperature variability is reduced
Solution Approach 1:
The patent divides the phosphor system into multiple independent phosphor types (first phosphor excited by blue LED, second phosphor excited by red LED, and third phosphor excited by both), each contributing to different wavelength ranges. This segmentation allows independent control of each phosphor's contribution to the overall spectrum, enabling both good color rendering and adjustable color temperature by varying the excitation power ratios.
Solution Approach 2:
The third phosphor layer serves multiple functions: it is excited by both blue and red LED light, allowing it to contribute to the spectrum under different operating conditions. This multi-functionality enables the system to maintain good color rendering while providing flexibility in color temperature adjustment, as the third phosphor can be activated by either or both LED types depending on the desired output.
2Illumination intensity
If turn-on power of blue LED is increased to enhance intermediate wavelength emission, then green to orange light intensity is improved, but high color temperature illumination cannot be achieved
Solution Approach 1:
The patent implements dynamic control of the blue and red LED excitation powers to achieve different color temperature outputs. By dynamically adjusting the power ratio between blue and red LEDs, the system can shift the dominant excitation source, thereby controlling which phosphors are primarily activated and achieving a wide range of color temperatures from high to low while maintaining appropriate intermediate wavelength content.
Solution Approach 2:
The system changes the excitation power parameters of the blue and red LEDs to control the relative intensity of light from different phosphors. By varying these power parameters, the system can adjust the overall color temperature while ensuring that the third phosphor receives sufficient excitation from the appropriate LED to maintain good color rendering in the intermediate wavelength range.
3Temperature
If turn-on power of red LED is controlled for color temperature adjustment, then low color temperature range is improved, but high color temperature range cannot be adjusted
Solution Approach 1:
The patent segments the color temperature control function between blue and red LED excitation. The red LED primarily controls the low color temperature range by exciting the second and third phosphors, while the blue LED controls the high color temperature range by exciting the first and third phosphors. This segmentation of control functions enables the system to achieve wide color temperature variability across both low and high 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
This configuration enables a wide range of color temperature variation and smooth adjustment, enhancing the ability to produce illumination light with desired color temperatures by compensating for intermediate wavelengths and optimizing light emission.
Implementation Method 1
a wavelength converter including phosphors that convert a wavelength of light emitted from each of the solid state light emitting elements
Implementation Method 2
the phosphors include two or more of a first phosphor, a second phosphor, and a third phosphor, the first phosphor being excited by light emitted from a solid state light emitting element
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A light emitting device (1) includes multiple types of solid state light emitting elements (2a, 2b) having different peak wavelengths from each other; and a wavelength converter (22) including phosphors (9) that convert a wavelength of light emitted from each of the solid state light emitting elements. The phosphors include two or more of a first phosphor (91), a second phosphor (92), and a third phosphor (93). The first phosphor is excited by light emitted from a solid state light emitting element (2a) having a relatively long peak wavelength, and the second phosphor is excited by light emitted from a solid state light emitting element (2b) having a relatively short peak wavelength. The third phosphor is excited by light emitted from any of the solid state light emitting elements.