Reflective Filter Lighting Device Reduces Blue Spike
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Solution Overview
Problem
Higher correlated color temperature (CCT) LEDs emit light with negative biological effects on the environment and are less stable over their lifespan, while methods to lower CCT, such as adding amber or red LEDs, increase costs and do not eliminate the blue wavelength spike.
Innovation Solution
A lighting device with a reflective filter that passes desired wavelengths and returns undesirable wavelengths to a wavelength shifter, which converts them into more desirable longer wavelengths, eliminating the blue spike and reducing heat absorption, thereby lowering CCT and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If higher CCT LEDs are used to improve luminous efficiency and reduce cost, then efficacy increases, but harmful environmental effects increase due to blue light emission
Solution Approach 1:
The patent converts the harmful blue light emission from high CCT LEDs into beneficial longer wavelength light through a two-stage wavelength conversion process. A first wavelength converter converts blue light to green light, and a second wavelength converter converts remaining blue light to yellow-green light, transforming the harmful blue spike into useful visible light that reduces environmental harm while maintaining efficiency
Solution Approach 2:
The patent introduces wavelength converters (phosphors) as intermediary substances between the blue LED light source and the final output. These converters act as mediators that transform the harmful blue wavelength into beneficial green and yellow-green wavelengths, allowing the system to maintain high efficiency while eliminating harmful effects
2Object-affected harmful factors
If absorptive filters are used to reduce blue light and lower CCT, then harmful effects decrease, but luminous efficiency decreases due to heat absorption and energy loss
Solution Approach 1:
Instead of absorbing and wasting blue light energy as heat, the patent uses wavelength converters to transform the blue light energy into useful green and yellow-green light energy. This converts what would be wasted energy into beneficial output, simultaneously reducing harmful effects and maintaining high luminous efficiency
Solution Approach 2:
The patent replaces the thermal absorption mechanism of conventional filters with an optical wavelength conversion mechanism. Instead of converting light energy to heat energy (absorption), the system converts light energy to light energy at different wavelengths (fluorescence/phosphorescence), eliminating heat generation and energy loss
3Temperature
If absorptive optical filters are used to lower CCT, then blue light is reduced, but optical filtering losses increase and efficiency decreases
Solution Approach 1:
The patent transforms the energy that would be lost through absorption into useful optical output by using wavelength converters to change blue light into green and yellow-green light. This eliminates optical filtering losses while achieving the desired color temperature reduction
Solution Approach 2:
The patent changes the wavelength parameter of the emitted light through phosphor conversion rather than filtering. By converting blue wavelength light to green and yellow-green wavelengths, the system achieves CCT reduction through parameter transformation rather than energy loss
4Temperature
If multiple LED types (amber or red LEDs) are added to lower CCT, then color temperature decreases, but device complexity and cost increase
Solution Approach 1:
The patent uses a single blue LED type combined with wavelength converters to achieve multiple functions: the blue LED provides the pump light, the first wavelength converter produces green light, and the second wavelength converter produces yellow-green light. This universal approach eliminates the need for multiple LED types while achieving CCT reduction and simplifying device complexity
Solution Approach 2:
The patent merges the functions of multiple LED types (blue, amber, red) into a single blue LED system with wavelength converters. Instead of using separate LED chips for different wavelengths, the system combines wavelength conversion functions to achieve the same effect, reducing component count and simplifying the device
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 produces a more pleasing, efficient, and potentially less hazardous light with lower power requirements, reducing the need for additional phosphors and associated costs, while maintaining a broad-spectrum output with high efficiency and low CCT.
Implementation Method 1
a reflective filter positioned in an optical path between an active light source and an exterior of the lighting device to filter the light before the light reaches the exterior of the lighting device
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 reflective filter and in response emit light at a shifted wavelength
Implementation Method 3
The phosphor layer is typically designed to convert radiation in the 440 to 480 nanometer wavelength range into a wider spectrum consisting of longer visible wavelengths
Data Source
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AI summary
The efficiency and color temperature 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 reflective filter (e.g., dichroic or dielectric mirror material) may pass desired wavelengths while returning or reflecting less desired wavelengths away from an optical exit back toward wavelength shifting material which may either be disposed in the optical path or on the periphery of the light source.