Double-Notch Reflective Filter for Phosphor Lighting
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Solution Overview
Problem
Phosphor-based solid-state lighting devices struggle to minimize undesirable blue light while maintaining efficiency and light output, as existing methods like absorption filtering result in significant losses and esthetic concerns related to color temperature and color contrast.
Innovation Solution
A lighting device incorporating a double-notch reflective filter that reflects undesirable wavelengths between 400 nm to 480 nm and 570 nm to 600 nm, combined with wavelength shifters to re-emit these wavelengths as more desirable red and green light, enhancing color contrast without significant energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If absorption filtering is used to remove blue light, then the undesirable blue light is reduced, but significant energy loss occurs
Solution Approach 1:
The patent converts the harmful blue light that would be absorbed and lost into a beneficial resource by using wavelength shifters to transform it into desirable red and green light. The double-notch reflective filter reflects the blue light (400-480nm) back onto the wavelength shifters, which then convert it to red and green wavelengths, thereby eliminating the harmful blue light while recovering the energy that would otherwise be lost.
Solution Approach 2:
The patent discards the undesirable blue light through selective reflection and recovers its energy value by converting it to useful red and green light. The reflective filter discards the blue portion of the spectrum, and the wavelength shifters recover the energy by re-emitting it at different, more desirable wavelengths.
2Object-generated harmful factors
If red and green light are added to white LEDs to provide a more pleasing spectrum, then color contrast is enhanced, but significant added cost for extra LEDs and drive electronics occurs
Solution Approach 1:
The patent changes the wavelength parameter of the light by using wavelength shifters that convert blue light (400-480nm) into red and green light. This parameter transformation allows a single blue LED to produce multiple wavelength outputs, eliminating the need for multiple LEDs and their associated drive electronics while still achieving the desired spectrum quality.
Solution Approach 2:
The patent makes the blue LED multi-functional by adding wavelength shifters that enable it to produce not only blue light but also red and green light. This single component performs the function of what would otherwise require multiple separate LEDs, simplifying the overall device architecture.
3Object-generated harmful factors
If phosphor formulation is adjusted to provide desired light, then some spectral improvement is achieved, but the blue wavelength spike remains due to the wideband nature of phosphor emission
Solution Approach 1:
The patent segments the broad phosphor emission spectrum by using a double-notch reflective filter that selectively reflects only the blue wavelength range (400-480nm) while allowing other wavelengths to pass. This segmentation isolates the problematic blue spike from the rest of the spectrum, enabling precise spectral control that phosphor formulation alone cannot achieve.
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 effectively reduces undesirable blue light, enhances the output of red and green wavelengths, and maintains high efficiency by recycling energy within the lighting device, resulting in a more pleasing and efficient light spectrum.
Implementation Method 1
at least one double-notch reflective filter positioned in an optical path between the active light source and an exterior of the lighting device to filter the light
Implementation Method 2
a wavelength shifter positioned and oriented to receive at least some of the light of the second set of wavelengths returned from the at least one double-notch reflective filter and in response emit light at shifted wavelengths
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The efficiency and color contrast of a lighting device may be improved by using wavelength shifting material, such as a phosphor, to absorb less desired wavelengths and transmit more desired wavelengths. A double-notch reflective filter may pass desired wavelengths such as red and green, while returning or reflecting less desired wavelengths (blue and yellow) away from an optical exit back toward wavelength shifting material and re-emitted as light of more desirable wavelengths.