Optical Sheet Anti-Glare Surface Roughness Control

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Solution Overview

Problem

Conventional anti-glare optical sheets used in ultrahigh-definition display elements fail to maintain image clarity and powerful moving image quality due to excessive light diffusion, as they are designed with a single cut-off value for surface roughness, which does not effectively balance the diffusion of both high and low frequency components.

Innovation Solution

The optical sheet is designed with two cut-off values and specific parameters for ten-point average roughness (Rz) and arithmetic average roughness (Ra), along with a standard deviation, to control the diffusion of transmitting and reflecting lights, ensuring optimal anti-glare properties, contrast, and image clarity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a single cut-off value is used for surface roughness control, then the anti-glare property is improved, but the image clarity and contrast deteriorate

Engineering Contradiction:
Improveanti-glare propertyVSAvoidimage clarity
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The invention divides the surface roughness control into two distinct segments: low-frequency components (long wavelength undulations) and high-frequency components (short wavelength irregularities). By controlling these two frequency components separately through dual cut-off values (0.8mm and 0.25mm), the patent achieves both anti-glare effect from low-frequency diffusion and image clarity from controlled high-frequency scattering, resolving the contradiction between anti-glare property and image clarity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the parameter control approach from a single cut-off value to dual cut-off values (0.8mm and 0.25mm), allowing independent optimization of low-frequency and high-frequency surface components. This parameter change enables the surface to simultaneously provide broad light diffusion for anti-glare while maintaining fine detail resolution for image clarity

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If the surface unevenness is increased to improve anti-glare property, then the contrast decreases due to excessive light diffusion

Engineering Contradiction:
Improveanti-glare propertyVSAvoidcontrast
Core Design Contradiction:
Object-affected harmful factorsVSIllumination intensity

Solution Approach 1:

The invention applies different roughness characteristics to different spatial frequencies of the surface. Low-frequency components (controlled by 0.8mm cut-off) provide the anti-glare function through broad diffusion, while high-frequency components (controlled by 0.25mm cut-off) are kept minimal to preserve contrast. This local quality differentiation allows the same surface to simultaneously achieve anti-glare effect and maintain contrast by assigning different functional qualities to different frequency domains

Inventive Principle:
Principle #3Local quality

3Object-affected harmful factors

If conventional surface roughness control is used, then the balance between anti-glare and contrast is achieved for standard displays, but the image clarity and powerfulness are lost in ultrahigh-definition displays

Engineering Contradiction:
Improveanti-glare propertyVSAvoidimage clarity
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The invention introduces a new parameter control scheme with dual cut-off values (0.8mm and 0.25mm) and specific roughness ranges (Rz0.8: 0.3-0.65μm, Rz0.25: 0.17-0.4μm) optimized for ultrahigh-definition displays. This parameter change allows the surface to provide sufficient diffusion for anti-glare while maintaining the fine scattering control needed for 250 ppi or higher pixel density displays, thereby preserving image clarity and powerfulness that were lost with conventional single cut-off value control

Inventive Principle:
Principle #35Parameter changes

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 effectively balances anti-glare properties, contrast, and image clarity, enabling the display of powerful moving images in ultrahigh-definition displays by precisely controlling the surface unevenness and light diffusion, particularly in high-definition displays with pixel densities of 250 ppi or more.

Implementation Method 1

the external light diffuses due to the uneven structure

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 2

prevent reflection of an external light

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentUS10859736B2Optical sheet, polarizing plate, optical sheet sorting method, optical sheet production method, and display device
Publication Date: 2020.12.08 DAI NIPPON PRINTING CO LTD

AI summary

Provided is an optical sheet which is excellent in anti-glare property, contrast, and image clarity, as well as capable of displaying a powerful moving image, wherein at least one surface of the optical sheet is an uneven surface, and the uneven surface satisfies following conditions (1) to (3), provided that Rz0.8 is a ten-point average roughness according to JIS B0601: 1994 with a cut-off value of 0.8 mm, Rz0.25 is a ten-point average roughness according to JIS B0601: 1994 with a cut-off value of 0.25 mm, and SD is a standard deviation of an arithmetic average roughness Ra0.8 according to JIS B0601: 1994 with a cut-off value of 0.8 mm:0.300 μm≤Rz0.8≤0.650 μm  (1)0.170 μm≤Rz0.25≤0.400 μm  (2)SD≤0.015 μm  (3).