Light Diffusion Sheet with Recesses and Projections for Thin LCDs
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Solution Overview
Problem
Existing light diffusion sheets in liquid crystal displays fail to adequately diffuse light, leading to uneven luminance and a decrease in luminance when the thickness of the display is reduced, which is necessary for thinner designs.
Innovation Solution
A light diffusion sheet with a first surface featuring recesses for diffusing light and a second surface with spaced projections that allow for an air layer, enhancing light diffusion and uniformity while maintaining luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the light diffusion sheet is increased to enhance in-plane uniformity of luminance, then in-plane uniformity is improved, but the luminance of transmitted light decreases and the overall thickness increases
Solution Approach 1:
The light diffusion sheet is segmented into multiple functional surfaces: a first surface with recesses for light diffusion and a second surface with projections for air layer formation. This segmentation allows each surface to perform its specific function optimally without compromising overall luminance transmission.
Solution Approach 2:
The light diffusion sheet combines multiple structural features (recesses on first surface, projections on second surface) into a composite optical structure. This composite design enables simultaneous achievement of light diffusion for uniformity and light transmission for maintaining luminance.
2Length of stationary object
If the thickness of the liquid crystal display is reduced by shortening the distance from light source to light diffusion sheet or thinning the light diffusion sheet, then thickness is reduced, but light diffusion becomes insufficient leading to luminance unevenness
Solution Approach 1:
The invention addresses light diffusion in the thickness direction by creating surface structures (recesses and projections) rather than relying solely on increasing sheet thickness. This dimensional approach allows effective light diffusion without increasing overall display thickness.
Solution Approach 2:
The recesses on the first surface and projections on the second surface introduce curved geometric features that enhance light scattering and diffusion. These curved structures effectively diffuse light even in thin sheets, maintaining uniformity without increasing thickness.
3Illumination intensity
If multiple light sources are used in a direct method backlight unit, then luminance can be increased, but luminance unevenness occurs between portions directly below LED elements and portions where no LED element is present
Solution Approach 1:
The light diffusion sheet applies different local structures at different surfaces: recesses on the first surface for diffusion and projections on the second surface for air layer creation. This local quality variation optimizes light distribution to reduce unevenness caused by discrete LED sources.
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 effectively inhibits a decrease in luminance and enhances in-plane uniformity, allowing for thinner liquid crystal displays with improved light distribution.
Implementation Method 1
a first surface on which a plurality of recesses that diffuse light are formed
Implementation Method 2
a second surface on which a plurality of projections that can transmit light are provided apart from each other
Data Source
AI summary
One aspect of the present invention is a light diffusion sheet having a first surface on which a plurality of recesses that diffuse light are formed, and a second surface on which a plurality of projections that can transmit light are provided apart from each other.