Inverted LED Substrate Curvature for Light Extraction

The patent applies a convex curvature to the substrate surface, creating a spherical or dome-shaped interface between the substrate and the LED structure. This curvature causes light rays that would otherwise be trapped by total internal reflection to strike the curved surface at angles less than the critical angle, enabling them to escape. The curved surface acts as an integrated optical element that improves light extraction without requiring separate roughening layers or complex multi-interface structures.

The patent merges the substrate function with the light extraction function by integrating the convex curvature directly into the substrate surface. This eliminates the need for separate convex lenses or additional optical interfaces that would increase the overall size of the light source. The substrate simultaneously serves as the mechanical support and the optical element that enables light extraction, achieving compact integration of multiple functions.

The patent changes the optical parameters of the substrate by introducing a convex curvature with a specific radius of curvature. This parameter change modifies the light extraction characteristics, allowing a single LED to achieve higher effective light output by reducing internal reflection losses. The curvature radius is optimized to balance light extraction efficiency with device compactness, enabling one LED to replace multiple LEDs in high-power applications.