Diffusion Sheet With Dual-Height Protrusions For Backlight Waviness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing backlight units for liquid crystal panels face challenges with waviness due to thinning of optical films, leading to optical and diffusion performance deterioration when attempting to integrate prism and diffusion sheets, resulting in thickness limitations and appearance defects.
Innovation Solution
A diffusion sheet and laminated prism sheet design featuring minute irregularities with specific height and width ratios for convex portions, where only the first convex portion is adhered to the adhesion layer, preventing waviness while maintaining optical and diffusion performance by avoiding adhesion of the second convex portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If prism sheets and diffusion sheets are made thinner to reduce backlight unit thickness, then the overall device becomes more compact, but waviness occurs due to heat radiation from LED causing mounting difficulties and appearance defects
Solution Approach 1:
The invention applies local quality by creating specific convex portions with different heights (first convex portions and second convex portions) at different locations on the diffusion sheet. The first convex portions have heights that prevent waviness when adhered to the prism sheet, while the second convex portions have lower heights that maintain diffusion performance. This localized differentiation resolves the contradiction between thinning the sheet and preventing waviness.
2Device complexity
If prism sheets and diffusion sheets are integrated by pasting them together, then manufacturing complexity is reduced, but adhesion layers fill the vertex portions of prism columns causing deterioration of optical performance and condensation performance
Solution Approach 1:
The invention resolves this contradiction by creating local quality differentiation through convex portions of different heights. The first convex portions (with heights greater than the adhesion layer thickness) are designed to be adhered to the prism sheet for integration, while the second convex portions (with lower heights) remain non-adhered to preserve optical performance. This selective adhesion approach enables integration without compromising optical characteristics.
Solution Approach 2:
The invention applies segmentation by dividing the surface of the diffusion sheet into different regions with distinct convex portions. The first convex portions are segmented for adhesion purposes, while the second convex portions are segmented for optical performance preservation. This segmentation allows the adhesion layer to cover only specific areas, preventing it from filling all vertex portions of prism columns and thus maintaining optical performance.
3Strength
If adhesion layers are used to integrate prism sheets and diffusion sheets, then the sheets are securely fixed, but the adhesion layers completely fill the diffusion layer at the surface causing remarkable loss of diffusion performance
Solution Approach 1:
The invention resolves this contradiction by creating local quality differentiation through convex portions of different heights. The first convex portions (with heights greater than the adhesion layer thickness) ensure secure adhesion strength, while the second convex portions (with lower heights than the adhesion layer thickness) remain exposed to maintain diffusion performance. This allows the adhesion layer to provide strong bonding without completely filling the diffusion layer surface.
Data Source
AI summary
Provided is a diffusion sheet having a function for preventing warping, and having excellent optical and diffusion characteristics. A diffusion sheet 1 has a minute roughness pattern formed on the surface thereof, the pattern configured such that first protrusions 3a having a first height and second protrusions 3b having a second height lower than the first height are disposed in parallel. A portion of the first protrusions 3a is bonded to a bonding layer on the rear surface of an upper-layer sheet laminated on the surface of a diffusion sheet 2, and the second protrusions 3b are not bonded to said bonding layer. The following relationships are satisfied: h1:h2=1:0.5-0.1, and w1:w2=1:1.0-0.1, where h1 is the height of the first protrusions 3a, w1 is the width of the first protrusions 3a, h2 is the height of the second protrusions 3b, and w2 is the width of the second protrusions 3b.