Light Management Unit for LCD Brightness and Color Banding
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Solution Overview
Problem
Existing optical display systems face challenges in achieving uniform brightness and reducing color banding artifacts, particularly in large LCDs and LCD-TVs, where light management is crucial due to increased power requirements and varying viewing angles.
Innovation Solution
A light management unit is introduced, comprising a directionally recycling layer with prism structures and a reflective polarizer, along with a diffusion structure to prevent colored bands, which includes features like roughened surfaces, light scattering particles, and refractive index mismatches to diffuse light and improve on-axis brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a prismatic structured surface film is used to enhance on-axis brightness, then on-axis illumination is improved, but off-axis illumination deteriorates and colored bands appear when viewed at oblique angles
Solution Approach 1:
The patent segments the light management function into multiple distinct layers: a prismatic layer for directional light control and a diffusion layer for uniformity. This segmentation allows each layer to perform its specialized function without the negative effects of the other, resolving the contradiction between brightness enhancement and colored band prevention.
Solution Approach 2:
The diffusion layer acts as an intermediary between the light source and the viewer, positioned between the prismatic layer and the display panel. It mediates the light output by scattering the concentrated light from the prisms, thereby eliminating colored bands while preserving the brightness enhancement effect.
2Use of energy by moving object
If light recycling is implemented to improve brightness efficiency, then on-axis illumination is enhanced, but viewing angle uniformity deteriorates
Solution Approach 1:
The patent applies local quality by creating different optical properties at different locations and angles. The prismatic layer provides directional light control for on-axis viewing, while the diffusion layer provides omnidirectional scattering for uniform off-axis viewing. This local differentiation resolves the contradiction between light recycling efficiency and viewing angle uniformity.
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 enhances on-axis brightness and reduces the visibility of colored bands, providing more uniform illumination and improved display performance by recycling light and diffusing it effectively, thus addressing the challenges of brightness and color banding in large LCDs and LCD-TVs.
Implementation Method 1
a reflective polarizer adapted to transmit light having a first polarization orientation and to reflect the light having a different polarization orientation
Implementation Method 2
The diffusion structure diffuses light that passes through the diffusion structure
Implementation Method 3
Brightness enhancement may be achieved with such prismatic structured surface films through a process of reflection and refraction
Implementation Method 4
Brightness enhancement may be achieved with such prismatic structured surface films through a process of reflection and refraction
Data Source
AI summary
A light management unit is described for attachment to a display module, especially suited for an LCD TV or LCD monitor. The light management unit includes a directionally recycling layer including a structured side and a planar side where the structured side includes prism structures. The light management unit also includes a reflective polarizer positioned on the planar side of the directionally recycling layer. The light management unit also includes a diffusion structure incorporated into either the directionally recycling layer or between the directional recycling layer and the reflective polarizer. The diffusion structure causes a level of diffusion that is sufficient to prevent the appearance of colored bands when a viewer positioned along a line of sight that is perpendicular to the direction of the prism structures views the light management unit, illuminated from below, at an oblique angle from a vertical axis.