Optical Manifold for Homogeneous LED Illumination
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Solution Overview
Problem
Current LED technologies face challenges in achieving uniform luminance and color consistency, particularly in combining the outputs of multiple LEDs for applications like automotive headlamps, where heat removal limitations and phosphor utilization inefficiencies result in non-uniform illumination and color temperature variations.
Innovation Solution
The development of optical manifolds that utilize principles of non-imaging optics to combine multiple LEDs into a single, homogeneous output, with a remote phosphor coating to maximize luminance and adjust chromaticity, and the ability to shape light sources into various forms such as rectangular or square shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple LEDs are closely packed to increase total luminance, then the light output is improved, but heat removal limitations and non-uniform illuminance worsen
Solution Approach 1:
The patent divides the light source into multiple spatially separated LED chips rather than closely packing them. Each chip is independently mounted on a circuit board with its own heat removal path, allowing thermal management while maintaining high total luminance through optical combination of multiple separated sources.
Solution Approach 2:
The patent introduces an optical manifold as an intermediary device that combines the light outputs from multiple spatially separated LED chips. The manifold uses reflective surfaces and optical paths to merge the separate light sources into a single homogeneous beam, achieving high total luminance without requiring close physical packing of the LEDs.
2Illumination intensity
If multiple LEDs are closely packed to increase total luminance, then the light output is improved, but continuity of illuminance and uniformity worsen
Solution Approach 1:
The optical manifold acts as an intermediary that homogenizes the light from multiple spatially separated LEDs. It uses reflective surfaces and optical paths to blend the individual light sources into a single uniform beam with continuous illuminance, eliminating dark zones between emitters while maintaining high total luminance.
Solution Approach 2:
The patent achieves homogeneous illuminance by using the optical manifold to blend light from multiple LEDs into a single uniform source. The manifold's design ensures that the combined output has uniform intensity distribution, eliminating the non-uniformity that would result from simply placing multiple LEDs close together.
3Ease of manufacture
If phosphor coating is applied directly onto LED chip to generate white light, then color conversion is achieved, but source area increases and luminance decreases
Solution Approach 1:
The patent extracts the phosphor coating from the LED chip surface and places it remotely on the optical manifold. This separation allows the LED chip to maintain its small emitting area and high luminance, while the phosphor converts the blue light to white light at a different location, preventing luminance reduction.
Solution Approach 2:
The optical manifold serves as an intermediary between the LED chip and the phosphor coating. The manifold collects and redirects blue light from the LED to the remotely located phosphor, which then converts it to white light. This intermediary arrangement enables white light generation without increasing the LED chip's source area or reducing its luminance.
4Ease of manufacture
If phosphor coating is applied directly onto LED chip, then white light is generated, but color-temperature variations and adhesion problems worsen
Solution Approach 1:
The patent extracts the phosphor coating from the LED chip and places it remotely on the optical manifold. This separation eliminates the adhesion problems caused by differential thermal expansion between the phosphor and chip, and also eliminates color-temperature variations across the chip surface, as the phosphor is now illuminated uniformly from below rather than applied directly to the chip.
Solution Approach 2:
The optical manifold acts as an intermediary that provides a stable, thermally isolated substrate for the phosphor coating. This separation eliminates the thermal stress and adhesion problems that occur when phosphor is directly applied to the hot LED chip, and also ensures uniform illumination of the phosphor for consistent color temperature across the entire white light output.
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 optical manifolds provide a cost-effective, high-flux, and high-intensity light source with improved uniformity and color consistency, addressing the limitations of existing LED technologies by efficiently combining multiple LEDs and optimizing phosphor utilization.
Implementation Method 1
The optical manifolds use principles of nonimaging optics
Implementation Method 2
a remote phosphor coating to maximize luminance and adjust chromaticity
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C~2D
AI summary
An optical manifold for efficiently combining a plurality of blue LEDs (11) outputs to illuminate a phosphor for a single, substantially homogeneous output, in a small, cost-effective package Embodiments are disclosed that use a single or multiple LEDs and a remote phosphor (746), and an intermediate wavelength-selective filter (761) arranged so that backscattered photoluminescence is recycled to boost the luminance and flux of the output aperture A further aperture mask is used to boost phosphor luminance with only modest lo of luminosity Alternative non- recycling embodiments provide blue and yellow light in collimated beams, either separately or combined into white