Light Diffusion Sheet Ridge Geometry for Uniform and Durable Backlights
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Solution Overview
Problem
Existing direct type backlights in liquid crystal displays suffer from insufficient damage resistance of light diffusion plates and other optical films, and there is a need for environmentally friendly materials.
Innovation Solution
A light diffusion sheet using a polycarbonate resin derived from biomass resources, featuring recesses in a substantially inverted polygon or truncated polygon pyramid shape with controlled height differences and ridge configurations, enhancing luminance uniformity and scratch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light diffusion plate with inverted pyramid recesses is used to improve luminance uniformity, then luminance uniformity is improved, but the plate becomes susceptible to wear and damage during transportation
Solution Approach 1:
The patent applies curvature to the ridge portions of the light diffusion plate by forming curved surfaces with specific radius of curvature (R1, R2) at the ridge portions between recesses. This curvature design prevents the ridges from being sharp and prone to damage, while still maintaining the light diffusion function. The curved surfaces have radius of curvature of 0.01 mm to 0.1 mm, which prevents wear and damage during transportation while preserving luminance uniformity.
Solution Approach 2:
The patent changes the geometric parameters of the ridge portions by controlling the radius of curvature (R1, R2) and the dimensions (a, b) of the curved surfaces. By optimizing these parameters within specific ranges, the plate achieves both good light diffusion performance and resistance to damage during handling and transportation.
2Object-affected harmful factors
If polycarbonate resin from biomass resources is used to be environmentally friendly, then environmental friendliness is improved, but manufacturing precision and damage resistance may be compromised
Solution Approach 1:
The patent specifies precise parameter ranges for the curved surface dimensions (a: 0.003 mm to 0.03 mm, b: 0.003 mm to 0.03 mm) and radius of curvature (R1: 0.01 mm to 0.1 mm, R2: 0.01 mm to 0.1 mm) to ensure manufacturing precision when using biomass-based polycarbonate resin. These controlled parameters maintain dimensional accuracy and functional performance while using environmentally friendly materials.
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 light diffusion sheet that is resistant to damage and maintains luminance uniformity even when layered, while being environmentally friendly.
Implementation Method 1
a light diffusion member (a light diffusion plate, a light diffusion sheet, or a light diffusion film) is used to avoid making the light sources themselves such as light emitting diodes (LEDs) traceable through a light-emitting surface and improving uniformity of in-plane luminance
Data Source
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AI summary
A light diffusion sheet 43 includes a polycarbonate resin including a first structural unit derived from a dihydroxy compound represented by the following formula (1). The light diffusion sheet 43 includes, at least in its first surface 43a, a plurality of recesses 22 formed in a substantially inverted polygon pyramid or in a substantially inverted truncated polygon pyramid. The ridge 23 parting the plurality of recesses 22 has a recessed shape between the intersections 23a, with respect to a straight line connecting the intersections 23a of the ridge 23. A ratio Wr/P is 0.3 or less, where P is the arrangement pitch of the plurality of recesses 22 and Wr is the dimension occupied by a curved portion at the top portion of the ridge 23 in the arrangement direction of the plurality of recesses 22. The maximum height difference d between the ridge 23 and the straight line connecting the intersections 23a of the ridge 23 is 1 µm or more and 10 µm or less.