LED Lamp Lens Structure for Higher Side Light Extraction
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Solution Overview
Problem
Current light-emitting element lamps face challenges in maximizing light extraction efficiency, particularly from the substrate sides, which limits their overall light emission output.
Innovation Solution
The introduction of a light-emitting element lamp configuration that includes a first lens with a spherical segment shape protruding from the substrate back surface and a second concave lens attached to the sides, optimizing the light extraction by reducing total reflection and increasing the percentage of light extracted from the sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a light-emitting element uses a sapphire substrate with conventional structure, then the device structure is simple, but the light extraction efficiency from substrate sides is low due to total reflection
Solution Approach 1:
The patent applies spherical segment lenses with curved surfaces to the substrate back surface and side surfaces. The first lens has a spherical cap shape with radius of curvature R1, and the second lens has a spherical cap shape with radius of curvature R2. These curved surfaces refract light to reduce total reflection at the substrate-air interface, thereby improving light extraction efficiency from the substrate sides while maintaining a relatively simple device structure.
Solution Approach 2:
The patent divides the light extraction function into two separate components: a first lens for extracting light from the substrate back surface and a second lens for extracting light from the substrate side surfaces. This segmentation allows each lens to be optimized for its specific function, with the first lens having larger radius of curvature for back surface extraction and the second lens having smaller radius of curvature for side surface extraction, thereby resolving the contradiction between structural simplicity and light extraction efficiency.
2Strength
If the substrate thickness is increased to 430 μm, then the mechanical strength is improved, but the percentage of light extracted from substrate sides increases to 36.0%, indicating higher total reflection loss
Solution Approach 1:
The patent applies the second lens with spherical cap shape to the side surfaces of the substrate. The curved surface of the second lens refracts the light that reaches the substrate sides, changing the extraction angle to be less than the critical angle, thereby reducing total reflection. This allows the substrate to maintain increased thickness (430 μm) for mechanical strength while the second lens recovers the light extraction efficiency by redirecting side-emitted light.
3Device complexity
If conventional light extraction methods are used without lenses, then the device complexity is low, but the overall light emission output is limited due to insufficient light extraction efficiency
Solution Approach 1:
The patent segments the light extraction function into two distinct lenses: the first lens for back surface extraction and the second lens for side surface extraction. This segmentation enables each lens to be optimized for its specific extraction direction, with the second lens specifically designed with smaller radius of curvature to handle side-emitted light. The result is improved overall light extraction efficiency and increased light emission output, justifying the moderate increase in device complexity.
Solution Approach 2:
The patent applies different lens configurations to different locations of the substrate: the first lens with larger radius of curvature (R1) is applied to the back surface where light extraction requires gentler refraction, while the second lens with smaller radius of curvature (R2) is applied to the side surfaces where more aggressive refraction is needed to overcome the critical angle limitation. This local differentiation optimizes light extraction at each location, thereby increasing overall light emission 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
This configuration significantly enhances the light extraction efficiency of the lamp, allowing for a higher percentage of emitted light to be extracted externally, thereby increasing the overall light emission output.
Implementation Method 1
the total reflection is likely to occur at the substrate interface (the substrate back surface and the substrate sides) of the light-emitting element
Implementation Method 2
a first lens of spherical segment shape provided by protruding from a substrate back surface... and a second lens attached to side of the light-emitting element and the protruding surface of the first lens
Data Source
AI summary
Provided is a light-emitting element lamp capable of increasing a light extraction efficiency and its manufacturing method. The light-emitting element lamp according to the present invention includes: a light-emitting element having a semiconductor layer provided on a substrate; a first lens of spherical segment shape provided by protruding from a surface on the opposite side of the semiconductor layer of the substrate and having a spherical cap that includes a bottom surface consisting of an attaching surface to the surface and a protruding surface from the surface and a radius of curvature R1; and a second lens attached to the side of the light-emitting element and the protruding surface of the first lens, in which the second lens has a concave curve from a peripheral side of the bottom surface of the first lens to the semiconductor layer side on the side of the light-emitting element.