Beam-Condensing Optical Sheet Rigidity for Large LCDs
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Solution Overview
Problem
Large-sized liquid crystal display devices face challenges with the rigidity and handling of traditional beam-condensing optical sheets, which lead to deflection and degradation in image quality due to increased screen size, especially when exceeding 50 inches, as they lack sufficient stiffness and are prone to waviness under heat.
Innovation Solution
A beam-condensing optical sheet with irregularity portions arranged on a light-transmissive base, featuring a lens pitch of 110 μm to 330 μm and surface roughness of 0.1 μm or less, combined with a reinforcing structure to enhance rigidity and prevent deflection, and a multi-layer base configuration to maintain necessary thickness and support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the screen size is expanded to 50 inches or larger, then the display area is increased, but the rigidity of the optical sheet becomes insufficient causing deflection
Solution Approach 1:
The patent transitions from a two-dimensional flat optical sheet to a three-dimensional structured sheet with protrusions and recesses. This dimensional change allows the sheet to maintain rigidity while keeping the overall thickness minimal, resolving the contradiction between large display area and sufficient rigidity.
Solution Approach 2:
The patent introduces curved surfaces through protrusions and recesses instead of flat surfaces. These curved structures increase the moment of inertia and bending stiffness of the optical sheet, enabling it to maintain rigidity across large 50-inch or larger display areas without excessive thickness.
2Length of moving object
If the thickness of the optical sheet is reduced, then the device is thinned, but the handling and assembly workability deteriorates
Solution Approach 1:
By introducing curved protrusions and recesses, the patent creates structural reinforcement that compensates for reduced thickness. The curved geometry provides inherent stiffness that maintains handling and assembly workability even when the overall sheet thickness is minimized for device thinning.
Solution Approach 2:
The patent divides the optical sheet into multiple regions with protrusions and recesses, creating a segmented structure that provides localized reinforcement. This segmentation allows the sheet to be thinner overall while maintaining sufficient rigidity and workability in critical areas.
3Strength
If the rigidity of the optical sheet is lowered, then the sheet becomes more flexible, but deflection due to heat increases causing image quality degradation
Solution Approach 1:
The curved protrusions and recesses create a structure with higher thermal stability. The three-dimensional geometry resists heat-induced deflection better than flat sheets, preventing image quality degradation while allowing sufficient flexibility for assembly.
Solution Approach 2:
The patent creates a composite structural design combining regions of varying thickness and curvature. This composite approach allows the sheet to have localized rigidity to resist heat deflection while maintaining overall flexibility for handling and assembly operations.
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 improves luminance characteristics and handling of large-sized liquid crystal display devices by maintaining rigidity and preventing waviness, ensuring high-quality image display and assembly efficiency.
Implementation Method 1
beam-condensing optical sheet having a large number of irregularity portions continuously arranged on one main surface of a light-transmissive base
Implementation Method 2
beam-condensing optical sheets or films (generally referred to as 'sheets', unless otherwise specifically noted) such as prism sheets or lens sheets aimed at aligning the direction of emission of light from the light source to the front direction
Data Source
AI summary
An optical sheet, a backlight device, and a liquid crystal display device are provided. The beam-condensing optical sheet includes a large number of irregularity portions arranged on one main surface of a light-transmissive base, in which a pitch of arrangement of the irregularity portions is 110 μm or more and 330 μm or less, and surface roughness (Ra) of the irregularity portion is 0.1 μm or less.