Light Emitting Device With Gradient Refractive Index Lens
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Solution Overview
Problem
Current light emitting devices with combined LEDs and lenses face issues with light distribution, as light reflected at the interface between the lens and air, or direct light from the LED, results in insufficient luminous intensity in the upward direction, leading to undesired light distribution properties.
Innovation Solution
A light emitting device design featuring a substrate with a light emitting element having a reflecting layer on its upper surface, a first light-transmissive member with a smaller refractive index than the second light-transmissive member, where the first member's surface tapers towards the substrate, and the second member covers the light emitting element, reducing light leakage in the upper surface direction and enhancing light distribution properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a secondary lens is combined with an LED to disperse light uniformly in a short irradiating distance, then the thickness of the device can be reduced, but light reflected at the interface between the lens and air layer, and/or direct light from the LED incident on the light-diffusing part, causes luminous intensity in the upward direction to increase due to scattering, resulting in insufficient decrease in upward luminous intensity and failure to achieve desired light distribution properties
Solution Approach 1:
The patent applies local quality by creating a light-transmissive member with a gradient refractive index structure, where the refractive index varies from the lower end to the upper end. This gradient structure is specifically designed to control light refraction at different heights, allowing the lower portion to redirect upward light while the upper portion maintains light transmission, thereby locally optimizing light distribution to reduce upward luminous intensity without compromising overall device thickness.
Solution Approach 2:
The patent implements parameter changes by utilizing a gradient refractive index in the light-transmissive member. The refractive index is not uniform but changes continuously from the lower end to the upper end, creating a gradient that optimizes light refraction at different positions. This parameter variation allows the structure to effectively redirect light paths, reducing upward luminous intensity while maintaining device compactness and achieving desired light distribution properties.
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 design effectively reduces light leakage in the upper surface direction and achieves desired light distribution properties by refracting light in an upward direction, improving light extraction efficiency and luminous intensity.
Implementation Method 1
The first light-transmissive member has a smaller refractive index than the second light-transmissive member
Data Source
AI summary
A light emitting device includes: a substrate; a light emitting element disposed on the substrate, the light emitting element having an upper surface and a lateral surface; a reflecting layer located on the upper surface of the light emitting element; a first light-transmissive member having a first surface in contact with the lateral surface of the light emitting element, and a second surface that is inclined toward the substrate in a direction outward from the light emitting element; and a second light-transmissive member in contact with the second surface and covering the light emitting element. A refractive index of the first light-transmissive is smaller than a refractive index of the second light-transmissive member.