LED Linear Light Uniform Far Field Illumination
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Solution Overview
Problem
High intensity linear lighting systems for machine vision applications, particularly for inspecting specular surfaces, face challenges with non-uniform far field radiance, leading to reduced signal-to-noise ratio and dynamic range due to the degradation of tungsten halogen lamps and poor far field uniformity.
Innovation Solution
A linear LED lighting system with high thermal conductivity chip-on-board technology, combined with high efficiency imaging optics and aberration-corrected cylindrical optics, provides a compact, reliable, and cost-effective solution for uniform spatial and angular light distribution, using a hybrid lens to image light uniformly from LED arrays to the far field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If tungsten halogen lamps are used for high intensity linear lighting, then high illumination intensity is achieved, but the lamp intensity degrades rapidly and far field uniformity is poor
Solution Approach 1:
The patent replaces the mechanical filament-based tungsten halogen lamp system with an LED-based lighting system. This substitution eliminates the filament burnout issue and rapid intensity degradation while maintaining high illumination intensity, directly resolving the reliability problem associated with traditional lamps.
Solution Approach 2:
The patent changes the light source technology parameter from incandescent (tungsten halogen) to semiconductor (LED) emission. This fundamental parameter change provides both high intensity output and long operational lifetime with stable intensity characteristics, addressing both the illumination intensity and reliability requirements.
2Illumination intensity
If tungsten halogen lamps are used for high intensity linear lighting, then high illumination intensity is achieved, but far field uniformity is poor
Solution Approach 1:
The patent segments the lighting system into multiple individual LED sources arranged in a linear array, with each LED coupled to its own optical elements. This segmentation allows independent optimization of each light source's angular distribution and position, enabling precise control over far field uniformity while maintaining high intensity.
Solution Approach 2:
The patent applies different optical characteristics to different regions of the lighting system by using individual optical elements for each LED. This allows local optimization of light distribution patterns to achieve uniform far field illumination while maintaining high intensity at each local source.
3Reliability
If pre-packaged LED devices are used, then LED technology benefits are achieved, but thermal impedance increases and optical performance decreases
Solution Approach 1:
The patent extracts the LED die from the pre-packaged device structure and mounts it directly to a custom-designed heat sink with optimized thermal and optical pathways. This extraction eliminates the intermediate thermal impedance layers and allows direct optimization of thermal management and optical performance without the constraints of pre-packaged devices.
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 LED-based system offers superior performance with high intensity and uniformity in both near and far fields, extending the length of the line source as needed, and enhancing contrast by using multiple colors, thus improving camera sensitivity and dynamic range.
Implementation Method 1
Light emitting diode (LED) linear lights with uniform far field
Implementation Method 2
high brightness light emitting diode (LED) light sources
Implementation Method 3
The LED or LED arrays are mounted to a high thermal conductivity circuit board comprising chip on board (COB) technology
Data Source
AI summary
Described is a light emitting diode (LED) linear illumination system that includes a linear array of LED groups, high efficiency non-imaging optics and aberration corrected imaging optics. Each LED group can include one or more LEDs. The system provides uniform high intensity in near and far fields. System applications include machine vision and inspection of high reflectivity targets. Illumination can include one or more colors, including white light. The described system has improved thermal and optical performance and is generally more compact and lower in cost relative to conventional systems based on pre-packaged commercially available LED devices.