Light Diverting Layer for Backlit Display Uniformity
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Solution Overview
Problem
Backlit liquid crystal displays (LCDs) face challenges in achieving uniform illumination due to the linear arrangement of cold cathode fluorescent lamps, leading to bright stripes and non-uniform brightness, especially in larger displays like LCD TVs, which require higher brightness and different viewing angles compared to smaller devices.
Innovation Solution
The implementation of a light diverting layer with a first surface facing the light sources and a second surface facing the diffuser, which diverts light in orthogonal planes to enhance uniformity, combined with a diffuser and reflective polarizer to optimize light distribution and recycling, is used between the light sources and the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If linear cold cathode fluorescent lamps are used to illuminate the display from behind, then the display can achieve sufficient brightness, but the illumination becomes non-uniform with bright stripes and darker regions
Solution Approach 1:
The light diverting layer segments the light paths from different lamp regions by using micro-prism structures that redirect light from specific angular ranges to different spatial locations, thereby distributing the light more uniformly across the display surface
Solution Approach 2:
The micro-prism structures in the light diverting layer have spatially varying orientations and geometries tailored to specific regions, with each local area optimized to redirect light from the non-uniform lamp distribution to achieve uniform illumination at the display panel
2Volume of moving object
If the separation between the diffuse reflector and the diffuser is reduced to make the display thinner, then the device complexity and volume decrease, but the illumination uniformity deteriorates
Solution Approach 1:
The light diverting layer acts as an intermediary component positioned between the lamp assembly and the diffuser, modifying the light distribution pattern before it reaches the diffuser, thereby enabling thin separation distances while maintaining illumination uniformity
Solution Approach 2:
The light diverting layer performs preliminary light redistribution at an early stage in the light path, pre-conditioning the illumination pattern before the light reaches the diffuser, which allows the system to achieve uniform illumination even with reduced component separation
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 configuration significantly improves brightness uniformity across the display, maintaining high brightness levels while reducing non-uniformity, allowing for thinner and more efficient illumination units with improved viewing angles.
Implementation Method 1
The light diverting layer comprises a first light-diverting surface facing the one or more light sources. The first light diverting surface diverts light normally incident on the light diverting layer primarily in a first diverting plane orthogonal to the light diverting layer.
Implementation Method 2
at least a second portion of the light from the one or more light sources that propagates within the light diverting layer in a direction substantially perpendicular to the light diverting layer being totally internally reflected at a sloped portion of the second light diverting surface
Implementation Method 3
A diffuser is disposed between the one or more light sources and the display panel
Implementation Method 4
combined with a diffuser and reflective polarizer to optimize light distribution and recycling
Implementation Method 5
combined with a diffuser and reflective polarizer to optimize light distribution and recycling
Data Source
AI summary
A directly illuminated display unit has a display panel and one or more light sources disposed behind the display panel. A diffuser is disposed between the one or more light sources and the display panel, and a light diverting layer is disposed between the one or more light sources and the diffuser. The light diverting layer has a first light-diverting surface facing the one or more light sources and a second light diverting surface facing the display panel. The light diverting layer diverts light passing from the one or more light sources to the diffuser, thus improving the uniformity of the light in the display unit.