Optical Stacks for Sparkle Reduction via Two-Directional Gratings

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Solution Overview

Problem

High definition displays with anti-glare coatings often suffer from sparkle issues due to non-uniformities in the optical path, which can be distracting and reduce perceived resolution when using one-directional periodic structures for diffraction, as they may compromise display resolution.

Innovation Solution

Incorporating optical stacks with two-directional gratings or multiple one-directional gratings, optimized for controlled diffraction, to reduce sparkle while maintaining display resolution, using polymeric materials and optically clear adhesives, and positioning diffraction peaks to minimize impact on image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If one-directional periodic structures are used for diffraction to reduce sparkle, then sparkle is reduced, but display resolution is compromised

Engineering Contradiction:
ImprovesparkleVSAvoiddisplay resolution
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent transitions from one-directional periodic structures to two-directional gratings, adding a second spatial dimension to the diffraction pattern. This dimensional change distributes diffraction peaks across multiple directions rather than concentrating them in a single direction, thereby reducing sparkle while preserving display resolution by spreading the diffraction effect more uniformly across the viewing field.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The optical element is divided into multiple distinct grating structures with different orientations. Instead of a single periodic structure, the patent employs multiple gratings arranged in different directions, each contributing to the overall diffraction pattern. This segmentation allows independent optimization of each grating's parameters to control sparkle reduction while maintaining resolution.

Inventive Principle:
Principle #1Segmentation

2Object-affected harmful factors

If anti-glare coatings are applied to high definition displays, then glare is reduced, but sparkle is generated due to non-uniformities

Engineering Contradiction:
ImproveglareVSAvoidsparkle
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent converts the non-uniformities in the optical path, which cause sparkle, into a beneficial effect by intentionally introducing controlled periodic structures. These structures create predictable diffraction patterns that can be engineered to reduce sparkle while maintaining the anti-glare function. The approach transforms random non-uniformities into controlled, uniform periodic structures that produce desirable optical effects.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent modifies the optical parameters of the system by introducing gratings with specific pitch values, orientations, and depths. By carefully selecting these parameters, the diffraction pattern can be controlled to redirect stray light away from the viewer's line of sight, thereby reducing sparkle. The parameter optimization ensures that the anti-glare coating's sparkle-generating effect is counteracted while preserving its glare-reduction benefit.

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 reduces sparkle in high definition displays without significantly compromising perceived resolution, by strategically placing diffraction peaks to minimize their degrading effect on image quality.

Implementation Method 1

an optical element for diffusing each of the pixels displayed by the display device so that each of the pixels has a plurality of peaks in the luminance distribution

Methodology Applied
Scientific EffectDiffraction: Diffraction

Data Source

PatentEP3155461B1Optical stacks for sparkle reduction
Publication Date: 2021.07.14 3M INNOVATIVE PROPERTIES CO
  • EP3155461B1 patent drawingFigure 1~2
  • EP3155461B1 patent drawingFigure 3A~3B
  • EP3155461B1 patent drawingFigure 3C~4

AI summary

Optical stacks including a grating structure that generates diffraction in two in-plane dimensions. The optical stacks may include two gratings, which may be one-directional or two-directional. The optical stacks are suitable for reducing sparkle in displays.