Multi-Pitch Prism Sheet for Thin Backlight Lamp Mura
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Solution Overview
Problem
Current liquid crystal display devices with direct lighting type back light units face challenges in reducing overall thickness while preventing lamp mura, which affects picture quality due to inefficient light scattering and convergence by existing prism sheets.
Innovation Solution
A prism sheet with multiple layers of prism mountains and a resin layer or diffusion agent, where the second prism mountains have a larger pitch than the first, effectively scattering and spreading light to prevent lamp mura and reduce back light unit thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the distance between lamps and diffusion plate is reduced to decrease back light unit thickness, then the overall thickness is reduced, but lamp mura occurs due to insufficient light scattering
Solution Approach 1:
The single prism sheet is divided into multiple prism sheets with different pitch values. The first prism sheet has a first pitch and the second prism sheet has a second pitch that is different from the first pitch. This segmentation allows each prism sheet to scatter light at different angles, effectively preventing lamp mura even when the distance between lamps and diffusion plate is reduced.
Solution Approach 2:
Different regions of the optical path are equipped with prism sheets having different local properties (different pitch values). The first prism sheet scatters light in one angular range while the second prism sheet scatters light in another angular range, creating a composite scattering effect that eliminates lamp mura across the entire display area.
2Device complexity
If optical sheets are removed to reduce device complexity and cost, then manufacturing is simplified, but lamp mura becomes more prominent
Solution Approach 1:
The multiple prism sheets with different pitch values perform multiple functions simultaneously: they scatter light to prevent lamp mura, control light distribution angles, and maintain image quality. This multi-functionality replaces what would otherwise require multiple different types of optical sheets, reducing overall device complexity while effectively eliminating lamp mura.
3Ease of manufacture
If a single prism sheet with uniform pitch is used, then manufacturing is simple, but light scattering is insufficient to prevent lamp mura in thin designs
Solution Approach 1:
The prism sheet structure is segmented into multiple layers, each with uniform pitch within its layer but different pitch values between layers. This segmentation maintains manufacturing simplicity for each individual layer while achieving superior light scattering performance through the combination of multiple layers with different pitch characteristics.
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 multi-layered prism sheet design uniformly scatters light, reducing the occurrence of lamp mura and enhancing picture quality by allowing for a thinner back light unit without compromising image clarity.
Implementation Method 1
a prism sheet which is made to improve lamp mura... the prism mountains scatter the light from the lamps toward the diffusion sheet
Data Source
AI summary
The present invention relates a prism sheet, and a back light unit and a liquid crystal display device therewith, in which total thickness of a back light unit is reduced while taking place of the lamp mura is prevented, for improving a picture quality.The prism sheet includes a plurality of first prism mountains formed on a supporting film at regular intervals, a resin layer filled between the first prism mountains, and a plurality of second prism mountains formed on the resin layer and the first prism mountains with at intervals greater than the intervals of the first prism mountains.