LED Wavelength Converter Angular Color Control
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Solution Overview
Problem
Conventional phosphor converted LEDs suffer from uncontrolled angular dependency and color non-uniformity, leading to reduced efficiency and increased production costs when attempting to address these issues.
Innovation Solution
A method is developed to control the angular dependency of LEDs with wavelength conversion by optimizing the height-to-width ratio of the wavelength converting element, allowing for a desired non-uniform angular color distribution, which is then translated into a uniform color distribution in the application, enhancing system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional phosphor converted LEDs are used, then light emission is achieved, but uncontrolled angular dependency and color non-uniformity occur
Solution Approach 1:
The patent applies local quality by creating different optical paths for different angular regions. The waveguide structure with specific geometry (thickness 1-10mm) and refractive index creates different light extraction characteristics for light at different angles from the LED, thereby achieving uniform color distribution across the viewing angle while maintaining efficient light emission.
Solution Approach 2:
The patent introduces a waveguide as an intermediary element between the LED and the final light output. This waveguide mediates the angular dependency by controlling light extraction through its geometric and optical properties, transforming the non-uniform angular color distribution from the LED into a uniform color distribution at the output.
2Manufacturing precision
If scattering particles are added to the phosphor material to mix converted and non-converted light, then color uniformity is improved, but device efficiency is reduced
Solution Approach 1:
The patent segments the light extraction function from the phosphor conversion function. Instead of mixing light within the phosphor material, the waveguide separates different angular components of light and extracts them at different locations, achieving color uniformity without requiring scattering particles that would reduce device efficiency.
3Manufacturing precision
If side emission is blocked to reduce angular dependency, then color uniformity is improved, but production cost increases
Solution Approach 1:
The waveguide performs multiple functions simultaneously: it guides light from the LED, controls angular dependency through its geometry, extracts light uniformly across different angles, and achieves color uniformity without requiring additional components like blocking coatings or scattering particles, thereby avoiding increased production costs.
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 approach increases the efficiency of the lighting system by maintaining a controlled angular color non-uniformity, optimizing light extraction and distribution, and reducing the need for costly solutions like blocking side emissions, resulting in improved performance compared to conventional uniform angular LED systems.
Implementation Method 1
LEDs use phosphor conversion of the primary emission to generate white light, but phosphors can also be used to create more saturated colors like red, green and yellow.
Implementation Method 2
a device that extracts light from the light source and translates the non-uniform angular color distribution into a uniform color distribution
Data Source
Figure 1~2A
Figure 2B~3A
Figure 3B~4
AI summary
A light source that uses a light emitting diode with a wavelength converting element is configured to produce a non-uniform angular color distribution that can be used with specific light based device that translate the angular color distribution into a uniform color distribution. The ratio of height and width for the wavelength converting element is selected to produce the desired non-uniform angular color distribution. The use of a controlled angular color non-uniformity in the light source and using it in applications that translate the non-uniformity into a uniform color distribution increases the efficiency of the system compared to conventional systems in which a uniform angular light emitting diode is used.