TFT-LCD Diffusion Sheet Refractive Index Optimization
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Solution Overview
Problem
Conventional diffusion sheets for TFT-LCD backlight units face challenges in achieving high luminance and total light transmittance due to limitations in the design of the light-diffusing layer, leading to increased power consumption and heat generation.
Innovation Solution
A diffusion sheet with a transparent base sheet, a light-diffusing layer, and an antiblocking layer, where the base sheet's refractive indexes in three directions satisfy a specific ratio, and the light-diffusing and antiblocking layers comprise specific resins and particles to enhance light transmittance and diffusibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of light sources in the backlight unit is increased to realize high image brightness, then luminance is improved, but power consumption and heat generation rates are increased
Solution Approach 1:
The patent changes the optical parameters of the base sheet by controlling the refractive index ratio SR to be greater than 20, which optimizes light transmission and diffusion efficiency, allowing high luminance with reduced power consumption
Solution Approach 2:
The patent uses a composite structure consisting of a transparent base sheet with specific refractive index properties and a light-diffusing layer containing resin and diffusion particles, achieving enhanced light efficiency without increasing power consumption
2Illumination intensity
If the number of light sources in the backlight unit is increased to realize high image brightness, then luminance is improved, but heat generation rates are increased
Solution Approach 1:
The patent optimizes the refractive index ratio SR of the base sheet to greater than 20, which improves light transmission efficiency and reduces heat generation while maintaining high luminance output
Solution Approach 2:
The composite structure of the base sheet and light-diffusing layer with specific refractive index properties enables efficient light transmission and diffusion, reducing heat generation rates while achieving high luminance
3Ease of manufacture
If conventional light-diffusing layer designs are used, then manufacturing is simpler, but total light transmittance and light diffusibility are insufficient
Solution Approach 1:
The patent specifies precise parameter ranges for the base sheet refractive index ratio SR > 20 and Nz ≤ 1.494, which optimizes total light transmittance while maintaining manufacturability through standard extrusion processes
Solution Approach 2:
The patent employs a composite light-diffusing layer comprising resin and diffusion particles with specific properties, achieving enhanced total light transmittance and light diffusibility while remaining compatible with conventional manufacturing methods
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 achieves superior total light transmittance and luminance, improving the light efficiency of the backlight unit while minimizing power consumption and heat generation.
Implementation Method 1
the base sheet satisfies Equation 1 below: SR=|(Nmax−Nz)/(Ntd−Nmd)|>20... Nmax is the greater value of either the refractive index of the sheet in a machinery direction (MD) or the refractive index of the sheet in a transverse direction (TD)... Nz is the refractive index of the sheet in a thickness direction
Implementation Method 2
a light-diffusing layer laminated on one surface of the base sheet... the light-diffusing layer may comprise a resin and diffusion particles... which can uniformly diffuse light from the light source
Implementation Method 3
an antiblocking layer laminated on the other surface of the base sheet
Data Source
AI summary
Disclosed herein is a diffusion sheet for use in a backlight unit of a TFT-LCD. Specifically, this invention provides a diffusion sheet including a transparent base sheet, a light-diffusing layer laminated on one surface of the base sheet, and an antiblocking layer laminated on the other surface of the base sheet, the base sheet satisfying a refractive index represented by a predetermined equation. According to this invention, the diffusion sheet for a display can uniformly diffuse light, which is radiated from a light source lamp positioned at a side surface or the back surface of the display, while passing such light therethrough, thus obtaining clear display images, resulting in increased total light transmittance, light diffusibility, and luminance.