Bottom-Surface LED Waveguide Lighting for Thin Display Uniformity
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Solution Overview
Problem
Conventional lighting devices for displays and general illumination are often thick and lack sufficient light mixing and uniformity, making them inefficient and unsuitable for thin form factors.
Innovation Solution
A lighting device with a solid, transparent waveguide and light sources positioned on its bottom surface, utilizing thin-film flip-chip LEDs and a photonic crystal structure to maximize light emission at large angles, combined with a dichroic filter and reflective cavities to enhance light distribution and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional lighting devices use traditional LED arrangements with reflective back planes and sidewalls, then sufficient illumination can be achieved, but the device thickness increases and light mixing uniformity decreases
Solution Approach 1:
The patent inverts the conventional LED backlight architecture by positioning LEDs at the bottom surface of the waveguide rather than at the rear panel. This inversion allows light to enter the waveguide from below and propagate through total internal reflection, achieving uniform illumination in a thinner profile without requiring thick reflective cavities
Solution Approach 2:
The patent transitions from a conventional planar LED arrangement to a three-dimensional waveguide structure where light propagates through the thickness dimension of the waveguide. This dimensional change enables light to travel laterally through the waveguide body, providing uniform illumination across the display area while maintaining thin overall device thickness
2Illumination intensity
If conventional lighting devices use traditional LED arrangements, then illumination can be provided, but light mixing and uniformity are insufficient
Solution Approach 1:
By inverting the LED placement to the bottom surface and utilizing the waveguide's internal reflection properties, light undergoes multiple reflections and scattering events as it propagates through the waveguide thickness, significantly improving light mixing and uniformity compared to conventional rear-panel LED arrangements
Solution Approach 2:
The patent modifies the optical path parameters by changing how light enters and propagates through the illumination medium. Light enters from the bottom at controlled angles and travels through the waveguide's thickness dimension, creating multiple interaction paths that enhance light mixing and achieve superior uniformity
3Illumination intensity
If conventional lighting devices use traditional structures, then illumination can be achieved, but the number of light sources required increases
Solution Approach 1:
The waveguide structure exploits the third dimension (thickness) to propagate light laterally over long distances with minimal loss. This enables a small number of bottom-surface LEDs to illuminate large display areas uniformly, reducing the total number of LEDs required compared to conventional planar arrangements
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 results in a thinner lighting system that provides sufficient illumination and uniformity, reducing the number of light sources required and minimizing bezel height while maintaining performance.
Implementation Method 1
a photonic crystal structure to maximize light emission at large angles
Implementation Method 2
a dichroic filter and reflective cavities to enhance light distribution and uniformity
Implementation Method 3
The back plane 48 and sidewalls 46 of the backlight 45 are covered with highly reflective materials
Implementation Method 4
Semiconductor light emitting devices such as light emitting diodes (LEDs) are among the most efficient light sources currently available
Data Source
Figure 1~3
Figure 4~5
AI summary
A device according to embodiments of the invention includes a waveguide (6), typically formed from a first section of transparent material. A light source (8) is disposed proximate a bottom surface of the waveguide. The light source comprises a semiconductor light emitting diode (12) and a second section of transparent material disposed between the semiconductor light emitting diode and the waveguide. Sidewalls (18) of the second section of transparent material ar reflective. A surface to be illuminated is disposed proximate a top surface of the waveguide. In some embodiments, an edge of the waveguide is curved.