Point Light Source Envelope Curvature for LED Extraction
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Solution Overview
Problem
Existing point light sources using LEDs suffer from low light extraction efficiency due to repeated reflections and increased optical path lengths, leading to brightness unevenness and reduced light utilization in planar light source devices.
Innovation Solution
A point light source design featuring a light-emitting element sealed within a light-transmitting envelope with specific surface geometries, including a protruding first surface and connected second, third, and fourth surfaces that reduce reflection and optical path length, enhancing light extraction efficiency by directing light efficiently into a light guide plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light is reflected repeatedly between the first and second planes of resin, then light can reach the light-emitting surface from multiple directions, but the optical path length becomes longer and light intensity is attenuated
Solution Approach 1:
The patent replaces the conventional planar resin surfaces with a spherical surface configuration. The resin is formed with a spherical surface having a radius of curvature R, where the LED chip is positioned at the center of the sphere. This spherical geometry allows light to be extracted more efficiently by utilizing the curved surface properties, reducing total internal reflection and shortening the optical path length compared to planar configurations.
2Ease of manufacture
If the light-emitting surface is orthogonal to the first and second planes, then the structure is simple and manufacturing is easier, but light reflected at large incidence angles is totally reflected and cannot be emitted
Solution Approach 1:
The patent employs a spherical surface configuration instead of orthogonal planar surfaces. The resin is formed with a spherical surface where the LED chip is positioned at the center, creating a hemispherical or spherical lens structure. This curved geometry naturally guides light rays at various incidence angles to exit the resin, preventing total internal reflection that occurs with planar surfaces, while maintaining manufacturing feasibility through molding processes.
3Stability of the object's composition
If light travels far in the light guide plate, then uniform brightness can be achieved, but repeated reflection causes attenuation and places far from the LED become darker
Solution Approach 1:
The spherical surface configuration of the resin reduces optical path length and minimizes light attenuation by eliminating repeated reflections at planar interfaces. By positioning the LED at the center of the spherical resin and utilizing the curved surface geometry, light is extracted more efficiently in all directions, providing sufficient illumination to the light guide plate without significant attenuation, thereby achieving better brightness uniformity across the display area.
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 design improves light utilization efficiency, resulting in uniform in-plane brightness and high display quality in planar light source devices by minimizing stray light and intensity attenuation, allowing light to travel further within the light guide plate.
Implementation Method 1
a point light source design featuring a light-emitting element sealed within a light-transmitting envelope with specific surface geometries
Implementation Method 2
including a protruding first surface and connected second, third, and fourth surfaces that reduce reflection and optical path length
Data Source
AI summary
An envelope of a point light source includes first to fourth surfaces. The first surface protrudes ahead of a light-emitting element and extends to a left side and a right side of the light-emitting element when viewed from the light-emitting element. The second surface is connected to the first surface on the left side and the right side of the light-emitting element and is in contact with the light-emitting element. The third surface is connected to an upper end of the first surface and an upper end of the second surface and forms a first depression that sinks from the first surface toward the second surface. The fourth surface is connected to a lower end of the first surface and a lower end of the second surface and forms a second depression that sinks from the first surface toward the second surface.