LED Encapsulant Meniscus Shape for Light Flux
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Solution Overview
Problem
Concave meniscus in conventional side view surface mount LEDs reduces light flux and color uniformity, particularly for high-brightness diodes with near-Lambertian far field patterns, which are advantageous for applications like backlighting in displays.
Innovation Solution
A light emitting diode package with a near-Lambertian reflector surface and a substantially flat or moderately domed encapsulant meniscus that enhances light output and far field uniformity, using a phosphor to convert frequencies and produce white light, while maintaining mechanical protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a concave meniscus is used in conventional side view surface mount LEDs, then the encapsulant is protected from mechanical damage, but light flux and color uniformity are reduced
Solution Approach 1:
The patent inverts the conventional concave meniscus shape to a convex meniscus shape. This inversion fundamentally changes the optical path and light distribution characteristics, allowing the encapsulant to maintain mechanical protection while significantly improving light flux and color uniformity by redirecting light in a more favorable pattern for side-view applications
Solution Approach 2:
The patent employs a convex curved surface (convex meniscus) instead of a flat or concave surface. This curvature is specifically designed to optimize light extraction and distribution in side-view LEDs, creating a shape that naturally guides light toward the sides while maintaining structural integrity and protecting the encapsulant
2Illumination intensity
If a concave meniscus is used to focus light for higher intensity, then directional intensity increases, but overall light flux is reduced
Solution Approach 1:
By inverting the meniscus from concave to convex, the patent reverses the focusing effect to a spreading effect. The convex shape distributes light more evenly across multiple directions, preventing excessive concentration in a single direction while maintaining high overall flux output, thus resolving the trade-off between directional intensity and total light quantity
3Illumination intensity
If a substantially flat or convex meniscus is used, then light flux and color uniformity are improved, but the encapsulant becomes more vulnerable to mechanical damage
Solution Approach 1:
The convex curved surface provides both optical benefits (improved light flux and color uniformity) and mechanical benefits (structural strength). The curvature distributes mechanical stresses more evenly across the encapsulant surface compared to flat designs, while simultaneously optimizing light extraction paths to achieve superior optical performance
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 improves light flux and color uniformity, optimizing light distribution for efficient backlighting in displays by focusing light within the intended plane while maintaining mechanical protection of the encapsulant.
Implementation Method 1
the use of yellow-emitting phosphors that convert the blue photons has likewise increased. Specifically, the combination of the blue light emitted by the diode and the yellow light emitted by the phosphor can create white light
Data Source
AI summary
A light emitting packaged diode ids disclosed that includes a light emitting diode mounted in a reflective package in which the surfaces adjacent the diode are near Lambertian reflectors. An encapsulant in the package is bordered by the Lambertian reflectors and a phosphor in the encapsulant converts frequencies emitted by the LED chip and, together with the frequencies emitted by the LED chip, produces white light. A substantially flat meniscus formed by the encapsulant defines the emitting surface of the packaged diode.