LED Array Orientation for Irradiance Uniformity
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Solution Overview
Problem
Illumination systems using LED arrays face challenges in achieving uniformity due to asymmetric optical characteristics, particularly 'odd function' tilts which conventional lens arrays cannot correct, necessitating expensive and complex optical apodizers.
Innovation Solution
The arrangement of LEDs in the array is optimized by orienting subsets of LEDs at specific angles (90°, 180°, or 270°) relative to each other, ensuring that the asymmetric optical characteristics are uniform across the array, which allows for the correction of odd-order non-uniformities without the need for additional optical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If LEDs in the array are arranged with the same clocking orientation, then the manufacturing and alignment process is simplified, but a tilt to the irradiance pattern is present which cannot be corrected by conventional lens arrays
Solution Approach 1:
The patent applies asymmetry by deliberately varying the clocking orientations of different LED subsets in the array. Instead of using uniform orientations, the invention uses multiple orientations (0°, 60°, 120°, 180°, 240°, 300°) to counterbalance the asymmetric emission patterns of individual LEDs, thereby achieving uniform irradiance distribution across the image plane.
Solution Approach 2:
The patent implements local quality by assigning different clocking orientations to different spatial subsets of LEDs within the array. Each subset's orientation is optimized for its specific location to compensate for local irradiance deficiencies, creating a globally uniform illumination pattern through locally tailored configurations.
2Manufacturing precision
If conventional lens arrays are used to correct non-uniformities in the irradiance pattern, then other types of non-uniformities can be corrected, but they are not suitable to correct the tilt caused by uniform LED clocking orientation
Solution Approach 1:
The patent extracts the tilt correction function from the optical system by incorporating it directly into the LED array configuration. Instead of using separate optical components to correct tilt, the invention embeds the correction capability in the spatial arrangement and orientation of LEDs themselves, eliminating the need for additional tilt-correcting optics.
Solution Approach 2:
The patent makes the LED array configuration multi-functional by designing it to simultaneously achieve uniform irradiance distribution and correct tilt. The same LED orientation pattern that creates uniformity also inherently corrects tilt, making the array structure serve multiple correction functions without requiring separate dedicated components.
3Manufacturing precision
If optical apodizers are added to correct for tilt in the irradiance pattern, then the uniformity is improved, but the system becomes more expensive and difficult to make and use
Solution Approach 1:
The patent implements self-service by enabling the LED array to correct its own irradiance non-uniformities and tilt through its internal configuration. The varied clocking orientations of LED subsets create a self-correcting system that automatically compensates for asymmetric emission patterns without requiring external correction components like apodizers.
Solution Approach 2:
The patent converts the harmful asymmetric emission pattern of individual LEDs into a beneficial uniform irradiance distribution. By strategically arranging LEDs with different clocking orientations, the inherent asymmetry of each LED is transformed into a corrective mechanism that balances the overall array output, turning a defect into a solution.
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 enables the creation of a uniform irradiance or intensity distribution at the image plane, correcting for asymmetries and improving the overall performance of the illumination system without the use of costly apodizers.
Implementation Method 1
an array of light emitting diodes (LEDs), each LED in the array having an asymmetric optical characteristic
Data Source
AI summary
An apparatus comprises an array of light emitting diodes (LEDs), each LED in the array having an asymmetric optical characteristic. The asymmetric optical characteristic of a first subset of LEDs in the array is oriented at an angle of 90°, 180°, or 270° with respect to the asymmetrical optical characteristic of a second subset of LEDs in the array. The apparatus may be the array of LEDs or an illumination system comprising a light source comprising the array of LEDs. Methods of manufacturing the apparatus are also provided.