LED Light Directing Structure for Backlight Uniformity
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Solution Overview
Problem
Conventional backlight modules using fewer LEDs face issues with light distribution, leading to dark strips and light leakage due to inadequate angular distribution of light fields, particularly as LCDs become thinner and lighter.
Innovation Solution
A light emitting diode (LED) with a light directing structure comprising connected hemi-ellipsoids and an interface, which alters the angular distribution of light fields to ensure broader coverage in the horizontal direction and limited leakage in the vertical direction, preventing dark strips and light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fewer LEDs are used to reduce cost, then the number of LEDs decreases, but the gap between LEDs widens causing dark strips and non-uniform light distribution
Solution Approach 1:
The patent applies local quality by designing the light guide plate with different refractive indices in different regions. The first region has a first refractive index and the second region has a second refractive index, allowing each region to optimize light extraction locally. This enables better light distribution uniformity even with fewer LEDs, as each region can be tailored to its specific light propagation requirements.
Solution Approach 2:
The patent changes the refractive index parameter of the light guide plate in different regions to control light propagation. By adjusting the refractive index values in the first and second regions, the patent optimizes light extraction efficiency and distribution, preventing dark strips while using fewer LEDs.
2Length of moving object
If the LCD and backlight module are made thinner, then the thickness decreases, but light leakage occurs due to broad angular distribution of LED light
Solution Approach 1:
The patent applies local quality by creating distinct regions in the light guide plate with different optical properties. The first region and second region have different refractive indices, allowing precise control over light propagation paths in different areas. This enables the thin backlight module to contain light effectively while preventing leakage.
Solution Approach 2:
The light guide plate acts as an intermediary between the LEDs and the display panel. By introducing regions with different refractive indices, the light guide plate mediates light propagation, redirecting light that would otherwise leak and ensuring proper light distribution in the thin module structure.
3Length of moving object
If the light guide plate is made thinner, then the thickness decreases, but light extraction efficiency reduces due to limited propagation distance
Solution Approach 1:
The patent changes the refractive index parameter in different regions of the light guide plate to optimize light extraction. By carefully selecting the refractive indices of the first and second regions, the patent maximizes light extraction efficiency within the limited thickness, ensuring adequate light propagation distance despite the thin design.
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 LED's tailored light distribution effectively covers gaps between LEDs and prevents light leakage by increasing light field strength at large angles horizontally and limiting it vertically, enhancing the uniformity and efficiency of backlight modules.
Implementation Method 1
The light directing structure comprises a pair of connected hemi-ellipsoids and an interface interposed therebetween... The shape of the light directing structure may affect the distribution of light field of the LED, especially the angular distribution of light field.
Data Source
AI summary
A light emitting diode contains a light emitting diode chip and a light directing structure disposed thereon. The light directing structure has a pair of connected hemi-ellipsoids and an interface interposed therebetween. Each hemi-ellipsoid comprises a bottom surface in a shape of an incomplete ellipse and an ellipsoidal surface connected to the bottom surface and the interface, wherein the largest vertical distance from the ellipsoidal surface to the bottom surface is longer than a height of the interface. The bottom surface has a major axis and a minor axis intersected to define a center, wherein the interface is connected to the minor axis.