Optical Member with 3D Structures for LCD Light Collection
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Solution Overview
Problem
Existing liquid crystal display (LCD) backlight units (BLUs) face challenges in minimizing light loss, achieving wider angular light collection, maintaining heat resistance, and preventing friction-related issues due to the expansion and shrinkage of diffusion plates, which limits their thickness and hiding performance.
Innovation Solution
An optical member with a substrate layer and a structural layer featuring three-dimensional structures with specific curvature and inclination angles, combined with a slip layer for reduced friction, is used to correct light paths and enhance light collection while maintaining heat resistance and hiding performance even at reduced distances from the light source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the distance between the light source and the diffusion plate is reduced to decrease the thickness of the BLU, then the thickness of the BLU is reduced, but hiding performance is reduced and friction-related issues occur due to thermal expansion
Solution Approach 1:
The diffusion plate is divided into a first region and a second region with different refractive indices. The first region has a higher refractive index than the second region, allowing each region to perform different optical functions. This segmentation enables the plate to maintain hiding performance while reducing thickness by optimizing light control in different zones.
Solution Approach 2:
Different regions of the diffusion plate are assigned different local optical properties (refractive indices). The first region with higher refractive index is positioned closer to the light source to handle hiding performance, while the second region with lower refractive index handles light diffusion. This local quality differentiation allows the plate to function effectively at reduced thickness.
2Productivity
If multiple sheets are mounted in the BLU to increase light efficiency, then light efficiency is improved, but the thickness of the BLU increases
Solution Approach 1:
Multiple optical functions (hiding, diffusion, light path control) that traditionally required separate sheets are merged into a single diffusion plate with a multi-region structure. The plate integrates the functions of what would otherwise require multiple separate components, maintaining light efficiency while reducing overall thickness.
Solution Approach 2:
The diffusion plate is designed to perform multiple functions simultaneously: hiding the light source, diffusing light, and controlling light paths. By making the plate multi-functional through its multi-region structure, the need for multiple separate sheets is eliminated, reducing thickness while maintaining light efficiency.
3Productivity
If the diffusion plate is exposed to heat from the light source for extended periods, then light efficiency is maintained, but deformation occurs due to thermal expansion
Solution Approach 1:
The refractive indices of different regions are specifically optimized to compensate for thermal expansion effects. By carefully selecting and positioning regions with different refractive indices, the optical performance remains stable even when the plate undergoes thermal expansion during extended operation near the light source.
4Ease of manufacture
If a conventional diffusion plate is used, then manufacturing is simple, but light loss occurs and luminance is reduced
Solution Approach 1:
The diffusion plate is segmented into regions with different refractive indices to optimize light control. This segmentation reduces light loss by directing light more efficiently through the plate, improving luminance while maintaining manufacturability through conventional multi-layer fabrication techniques.
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 optical member effectively minimizes light loss, increases luminance, maintains hiding performance, and prevents scratches or noise due to thermal expansion, allowing for thinner BLUs with improved light collection and stability.
Implementation Method 1
each of the 3D structures of the structural layer includes, when viewed in longitudinal cross-section, a first zone having a predetermined curvature k in both directions from a peak thereof... and two second zones abutting on both sides of the first zone and having an inclination angle relative to the substrate layer
Implementation Method 2
the loss of light occurs, undesirably resulting in reduced luminance... as part of the light which is not collected is reflected back from the prism sheet
Implementation Method 3
support pins are provided between the plurality of light sources to hold the diffusion plate disposed on the light sources... the diffusion plate may expand and then shrink or may expand too quickly, due to the change in temperature... causing problems in which the diffusion plate is scratched or noise occurs
Data Source
AI summary
Disclosed is an optical member for use in liquid crystal displays, which can correct the light path and can minimize the loss of light, so that light in a wider angular range can be collected forwards. Even when a distance between the optical member and a light source is shortened, the optical member can exhibit good hiding performance and prevent deformation caused by heat. Upon expansion and shrinkage, the optical member is not scratched and does not generate noise at a portion in contact with a support pin.