Optical Laminate Surface Profile for Sparkle and Fingerprint Control
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Solution Overview
Problem
Existing antiglare films for displays suffer from sparkle and fingerprint issues, with conventional stain-proofing components providing limited improvement in fingerprint removability, and surface unevenness leading to a trade-off between sparkle resistance and optical properties.
Innovation Solution
An optical laminate with a specific surface uneven shape characterized by spatial frequency conditions (80≤A≤5,500 and 0<B≤100) is developed, incorporating organic and inorganic fine particles, and a stain-proofing component to enhance fingerprint removability and sparkle resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If surface unevenness is increased to scatter light and prevent ambient light appearance, then antiglare property is improved, but sparkle occurs due to lens effect of unevenness
Solution Approach 1:
The patent applies parameter changes by precisely controlling the spatial frequency distribution of surface unevenness. Specifically, it limits the power spectrum intensity in the mid-spatial frequency range (50-200 cycles/mm) to reduce sparkle-causing lens effects, while maintaining adequate scattering in other frequency ranges to prevent ambient light appearance. This quantitative control of surface profile parameters resolves the contradiction between antiglare and sparkle resistance.
Solution Approach 2:
The patent applies local quality by creating different surface unevenness characteristics in different spatial frequency domains. The surface is designed to have specific scattering properties for certain spatial frequencies while having suppressed lens-like properties for other frequencies. This localized control of surface morphology allows simultaneous achievement of antiglare and sparkle resistance.
2Object-generated harmful factors
If difference between refractive index of resin and filler particles is increased to cause internal scattering and mitigate sparkle, then sparkle resistance is improved, but outer appearance is whitened
Solution Approach 1:
The patent applies parameter changes by optimizing the refractive index difference between resin and filler particles within a specific range (0.05≤n1-n2≤0.20). This controlled parameter adjustment provides sufficient internal scattering to mitigate sparkle while preventing excessive scattering that would cause whitening of the outer appearance.
3Ease of operation
If stain-proofing component is added to improve fingerprint removability, then fingerprint removability is improved, but sparkle resistance and optical properties are compromised
Solution Approach 1:
The patent applies local quality by concentrating the stain-proofing component specifically in the topmost surface layer rather than distributing it throughout the entire antiglare layer. This localized placement improves fingerprint removability at the surface while minimizing the component's impact on the bulk optical properties and sparkle resistance of the antiglare structure.
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 laminate achieves excellent sparkle resistance and fingerprint removability, maintaining optimal optical properties without surface whitening, suitable for high-definition displays.
Implementation Method 1
the surface unevenness functions as a lens, so that 'sparkle' which disturbs a display image is likely to occur
Data Source
AI summary
Provided are an optical laminate that is excellent in sparkle resistance and fingerprint removability, and an image display device using the same. The optical laminate has an uneven shape on a topmost surface, and satisfies a condition (1): 800≤A≤5,500, and a condition (2): 0<B≤100. Here, A and B are values calculated from a second image obtained by performing fast Fourier transform on a first image obtained from three-dimensional data of unevenness heights obtained by measuring the uneven shape through optical interferometry or in a contact manner. A is an average value of power spectrum intensities in a range of 50 cycles/mm≤f≤100 cycles/mm, and B is an average value of power spectrum intensities in a range of 200 cycles/mm≤f≤250 cycles/mm.