Reverse TIR Lens Features for LED Light Extraction
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Solution Overview
Problem
Current lighting technologies using arrays of LEDs face challenges in achieving uniform color mixing and optical efficiency due to physical arrangement of source elements, leading to issues like color separation and significant optical loss from diffusive materials.
Innovation Solution
The use of an elongated lens with reverse total internal reflection (TIR) features, where recessed areas on the receiving surface align with light emitters to couple and redirect light, improving light extraction and reducing hot spots, thereby enhancing output uniformity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If diffusive materials are used to blend light from multiple LED sources, then color mixing is improved, but optical loss increases significantly
Solution Approach 1:
Instead of using diffusive materials to scatter light (conventional approach), the patent uses reflective surfaces to redirect light in a controlled manner. The recessed features act as light traps that reflect light multiple times, achieving color mixing through reflection rather than diffusion, thereby reducing optical loss while maintaining uniformity.
Solution Approach 2:
The lens is segmented into multiple recessed features (wells) that correspond to individual LED sources. Each recessed feature independently manages light from a specific LED, allowing localized color mixing and reflection. This segmentation enables precise control over light paths and reduces the need for bulk diffusive materials that cause significant optical loss.
2Area of stationary object
If LED arrays are arranged in linear configurations, then space efficiency is improved, but color separation and non-uniform output occur
Solution Approach 1:
The patent introduces a vertical dimension by creating recessed features (wells) that extend into the lens body. This three-dimensional structure allows light from linearly arranged LEDs to be redirected and mixed in the vertical space within the lens, achieving uniform color output without compromising the space-efficient linear arrangement of the LED array.
Solution Approach 2:
Each recessed feature is specifically designed to interact with light from a corresponding LED source. The shape, depth, and positioning of each recessed feature are optimized for its local function of trapping and redirecting light from that specific LED, ensuring uniform contribution from each source to the overall output while maintaining the compact linear form factor.
3Ease of manufacture
If conventional lens designs are used with LED arrays, then manufacturing simplicity is maintained, but light extraction efficiency is reduced due to hot spots
Solution Approach 1:
The recessed features are pre-formed as integral parts of the lens molding process. This preliminary structuring of the lens with built-in light-trapping wells eliminates the need for post-manufacturing modifications or additional components. The features are created during the same injection molding process that forms the lens body, maintaining manufacturing simplicity while dramatically improving light extraction efficiency by preventing hot spots.
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 implementation of reverse TIR features in the elongated lens improves light output uniformity and efficiency by reducing absorption and enhancing the blending of light from multiple sources, resulting in a more uniform and efficient LED lighting system.
Implementation Method 1
reverse total internal reflection (TIR) features, where recessed areas on the receiving surface align with light emitters to couple and redirect light
Data Source
AI summary
An elongated lens profile having reverse total internal reflection (TIR) features that improve light extraction when the lens is used in conjunction with a plurality of light emitters. Solid state light emitters, such as LEDs, are arranged proximate to the elongated lens along a longitudinal axis of the lens body. The emitters, which may be grouped in clusters, emit toward a receiving surface of the lens. The receiving surface includes a plurality of reverse TIR features, also disposed along the longitudinal axis. These features may be defined by a series of recessed areas spaced along the longitudinal axis to correspond with the light emitters which can protrude into the negative space created by the recessed features. The recessed features may have more than one shape. The reverse TIR features improve light output uniformity, reducing hot spots along the lens, and improve output efficiency.