Color-Tuned LED Device with Scattering Element
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Solution Overview
Problem
Phosphor-based light-emitting devices face challenges such as light-energy losses, self-heating, and degradation due to temperature and light intensity variations, leading to unstable emission spectra and chromaticity over time.
Innovation Solution
A light-emitting device configuration featuring multiple light-emitting elements with different spectral compositions and a scattering element that includes inelastic scattering material, allowing for adjustable power distribution and feedback control to maintain consistent emission spectra and chromaticity, using a substrate with a scattering element and an extractor element to manage light refraction and minimize total internal reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If phosphor-based light-emitting devices are used to generate white light via down-conversion, then luminous efficacy and longevity are improved, but light-energy losses and phosphor self-heating occur due to Stokes loss
Solution Approach 1:
The device segments the light-emitting function into multiple independent LEEs with different spectral compositions (e.g., blue, green, red LEDs) rather than using a single phosphor-based conversion system. This allows direct emission of desired wavelengths without Stokes loss, eliminating the energy conversion inefficiency while maintaining longevity.
Solution Approach 2:
The patent employs a composite light-emitting structure combining multiple LEE types (different LED materials and phosphors) within a single device. By integrating blue LEEs with yellow phosphor, green LEEs with red phosphor, and red LEEs, the system achieves full-spectrum white light emission with improved energy efficiency and reduced thermal losses.
2Illumination intensity
If phosphor-based light-emitting devices operate at high intensity, then luminous output is improved, but degradation occurs due to permanent changes in chemical and physical composition of phosphors
Solution Approach 1:
The device divides the high-intensity light-emitting task across multiple LEEs with different spectral characteristics rather than overloading a single phosphor system. Each LEE operates at optimized intensity levels, preventing excessive thermal stress and chemical degradation of any single phosphor material, thereby maintaining reliability at high overall luminous output.
Solution Approach 2:
The patent dynamically adjusts the operating parameters (current, voltage, intensity) of individual LEEs based on their specific spectral characteristics and degradation profiles. By optimizing each LEE's operating point, the system maintains high luminous output while minimizing degradation rates, extending device lifetime.
3Adaptability or versatility
If multiple light-emitting elements with different spectral compositions are used, then color tuning capability is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple LEEs with different spectral compositions into a single integrated light-emitting device structure. By combining blue, green, and red LEEs (and their associated phosphors) within one housing with shared optical elements and control circuitry, the system achieves full color tuning capability without proportionally increasing overall device complexity.
Solution Approach 2:
The device employs universal optical components (scattering elements, light guides, extraction structures) that serve multiple functions across different LEE types. A single scattering element manages light from all LEEs, and a unified control system regulates all LEEs, reducing the complexity increment despite enhanced color tuning versatility.
4Illumination intensity
If phosphor conversion is used to achieve white light, then spectral composition is improved, but chromaticity stability deteriorates due to temperature and intensity variations
Solution Approach 1:
The patent segments the white light generation into multiple independent LEEs, each emitting at a fixed, stable wavelength. By directly emitting primary colors (blue, green, red) from separate LEEs rather than relying on phosphor conversion of a single wavelength, the system achieves stable chromaticity that is insensitive to temperature and intensity variations affecting phosphor materials.
Solution Approach 2:
The device incorporates feedback control mechanisms that monitor the output of each LEE and adjust their respective drive currents to maintain stable chromaticity. By detecting shifts in spectral composition and dynamically compensating through individual LEE adjustment, the system maintains consistent color output despite environmental variations.
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 stabilizes the emission spectrum and chromaticity of the light-emitting device, reducing the impact of phosphor degradation and temperature variations, enabling consistent color output over the device's lifetime.
Implementation Method 1
a scattering element that includes inelastic scattering material, where the scattering element surrounds, at least in part, the at least one first and second LEEs to scatter light emitted from the at least one first and second LEEs
Implementation Method 2
at least one first light-emitting element (LEE) disposed on the first surface for emitting light having a first spectral composition; at least one second LEE disposed on the first surface for emitting light having a second spectral composition
Data Source
AI summary
A variety of light-emitting devices for general illumination utilizing solid state light sources (e.g., light-emitting diodes) are disclosed. A light-emitting device can include a first light-emitting element (LEE) for emitting light having a first spectral composition, a second LEE for emitting light having a second spectral composition, and a scattering element surrounding at least in part the first and second LEEs to scatter light emitted from the first and second LEEs. The light-emitting device can also include electrical connections for connecting the first and second LEEs to a power source, where the electrical connections are arranged such that power to the first LEE is separately adjustable relative to power to the second LEE.