LED Array Illumination with Etendue Conservation
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Solution Overview
Problem
Conventional multi-color semiconductor light sources face issues with non-uniform color mixing and high etendue, leading to reduced brightness in applications requiring specific light spot sizes and limited etendue.
Innovation Solution
A light source with an LED array and collimator array, where each LED unit is covered by a high-refractive index medium with a thickness less than 50% of the LED chip's diameter, and a light homogenizing device such as a fly-eye lens pair or diffractive optical element, maintaining the etendue of the light unchanged to maximize brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a silicone lens is used to seal the LED chip and enhance light extraction efficiency, then the total luminous flux is increased by 20-30%, but the etendue is increased by 2-2.5 times, significantly reducing emission brightness
Solution Approach 1:
The invention removes the silicone lens from the LED packaging structure. By extracting this component that causes etendue expansion, the patent achieves minimal etendue output while maintaining effective light extraction through alternative means such as direct LED chip design and optimized phosphor integration.
Solution Approach 2:
The invention changes the optical parameters by eliminating the lens material interface and adjusting the phosphor layer thickness and composition. This allows optimization of light extraction efficiency without the etendue-multiplying effect of a silicone lens, achieving a different operational regime for the LED system.
2Productivity
If a TIR lens is used to collect light emitted at all angles, then light collection efficiency is improved, but the etendue of the output light becomes far greater than the etendue of the light source, significantly reducing light emission brightness
Solution Approach 1:
The invention extracts and removes the TIR lens from the optical system. By eliminating this component, the patent avoids the etendue expansion that occurs with angular light collection, achieving a different approach to light management that prioritizes etendue conservation over maximum angular collection.
3Adaptability or versatility
If dichroic filters are used to combine lights from different color LED arrays, then wavelength-based combination is achieved, but the system can only combine monochromatic lights with no wavelength overlap and cannot combine wide-band light such as white light
Solution Approach 1:
The invention merges multiple LED chips with different phosphor materials directly in close proximity without dichroic filters. This direct spatial combination allows different wavelength ranges to be emitted simultaneously from the same location, achieving spectral combination while maintaining system simplicity and enabling wide-band 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 solution minimizes the etendue of the output light, thereby maximizing emission brightness and achieving uniform color mixing, suitable for applications like stage lighting and projection.
Implementation Method 1
The surface of the LED chip is covered by a high-refractive index transparent medium having a refractive index greater than 1.3
Implementation Method 2
This collimating device is typically referred to as a total internal reflection (TIR) lens, and its principle is to use refraction by the center curved surface 1201a and total reflection by the surrounding side call 1201b to collimate the light of the LED
Implementation Method 3
This collimating device is typically referred to as a total internal reflection (TIR) lens, and its principle is to use refraction by the center curved surface 1201a and total reflection by the surrounding side call 1201b to collimate the light of the LED
Implementation Method 4
The light from the LED, after collimation by the collimators, are incident on a fly-eye lens to make the light from different color LEDs uniform
Data Source
Figure 1a~2
Figure 3a~4b
Figure 5a~6
AI summary
Light source comprises a light emitting diode array (101) and a collimator array (102). The light emitting diode array (101) comprises at least two light emitting diode units (101a, 101b) that emit light of different colors; the collimator array (102) is used for collimating light emitted by the light emitting diode units (101a, 101b) and keep the optical extension of the light emitted by the light emitting diode units (101a, 101b) substantially unchanged. The light source further comprises a dodging device (103) used for dodging light emerging from the collimator array (102). An illuminating device comprises the light source. The light emitting diode units (101a, 101b) and the collimator unit (102a) in the light source and the illuminating device minimize the optical extension of the emergent light, thereby maximizing the luminance.