Backlight Unit Light Guide Groove Design for Uniform Luminance
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Solution Overview
Problem
Conventional light guide members in backlight units (BLUs) fail to provide uniformly distributed light, leading to non-uniform luminance and image quality issues in display devices, and the use of additional optical sheets to address this problem increases cost, weight, and size.
Innovation Solution
A light guide member with grooves of varying widths and depths on its sides to redirect light uniformly, using a prism sheet as the optical member to enhance vertical directionality and collect light, thereby achieving uniform luminance distribution without the need for additional optical sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional light guide members are used to guide light from light sources, then light can be directed to the display panel, but the luminance distribution becomes non-uniform with bright lines and dark areas appearing
Solution Approach 1:
The light guide member incorporates grooves with varying widths and depths at different locations along its length. The groove configuration changes locally to compensate for position-dependent light loss, with wider/deeper grooves positioned where light intensity is lower and narrower/shallower grooves where light intensity is higher, thereby achieving uniform luminance distribution across the entire light guide output
Solution Approach 2:
The grooves in the light guide member are designed with asymmetric width and depth characteristics that vary along the light guide length. This asymmetric configuration allows different regions of the light guide to have different light extraction characteristics, compensating for the inherent symmetry breaking caused by light source positioning and radiation angle variations
2Illumination intensity
If additional optical sheets are added to improve light uniformity, then luminance distribution improves, but cost, weight, and size increase
Solution Approach 1:
The invention merges the light guiding function and the light uniforming function into a single integrated light guide member structure. By incorporating the groove features directly into the light guide body, the design eliminates the need for separate optical sheets that would otherwise be required to achieve uniform luminance distribution, thereby reducing weight while maintaining uniformity
3Ease of manufacture
If light guide members are designed with uniform groove structures, then manufacturing is simplified, but light distribution uniformity deteriorates
Solution Approach 1:
The light guide member incorporates grooves with varying widths and depths at different locations along its length. The groove configuration changes locally to compensate for position-dependent light loss, with wider/deeper grooves positioned where light intensity is lower and narrower/shallower grooves where light intensity is higher, thereby achieving uniform luminance distribution across the entire light guide output
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 provides a thinner and lighter BLU with substantially uniform luminance distribution, improving image quality and reducing the bright-line effect, while maintaining the structural integrity and cost-effectiveness of the display device.
Implementation Method 1
A light guide member with grooves of varying widths and depths on its sides to redirect light uniformly
Implementation Method 2
The diffusion of light is also generally weak at a portion of a light guide member close to the light source
Implementation Method 3
using a prism sheet as the optical member to enhance vertical directionality and collect light
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A light guide member for guiding light received from a light source unit, the light source unit illuminating light toward the light guide member, the light guide member may include a first groove on a first side of the light guide member, wherein at least one of a first width and a first depth of a first portion of the first groove may be different from a second width and a second depth of a second portion of the first groove based on a respective radiation angle of the light illuminating the first portion and the second portion of the light guide member.