Pyramidal Structured Surfaces for Rotation-Based Color Shift

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Solution Overview

Problem

Existing color-shifting coatings require the observer to change the angle of the substrate relative to the light source to achieve a color shift, limiting their application in creating dynamic color effects through rotation.

Innovation Solution

An array of pyramidal structures coated with optically variable color-shifting coatings on a substrate, where each structure has at least three slanted faces, allowing color variation when the substrate or viewer rotates, with the coating design optimizing dielectric thickness and geometry to enhance color shift effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional color-shifting coatings are applied to a substrate, then the coating exhibits color shift when the viewing angle changes, but the observer must actively shift the substrate angle relative to the light source to achieve the color shift effect

Engineering Contradiction:
Improveease of achieving color shiftVSAvoidcomplexity of structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The substrate surface is segmented into an array of pyramidal structures, each with multiple slanted faces. This segmentation allows different faces to present different colors at different rotation angles, enabling passive color shift observation without requiring the observer to actively change the viewing angle. The pyramidal geometry divides the surface into discrete optical elements that collectively produce the color shift effect through rotation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention introduces rotational dynamics to the substrate, transforming it from a static surface to a dynamically rotatable one. As the substrate rotates, the pyramidal structures present different faces to the observer, dynamically changing the perceived color. This dynamic rotation replaces the need for active viewing angle adjustment, making the color shift effect easier to observe while adding rotational movement capability.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If the substrate is made rotatable to enable color variation by rotation, then dynamic color effects are achieved, but the structural complexity increases

Engineering Contradiction:
Improveversatility of color displayVSAvoidcomplexity of structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention adds a rotational dimension to the substrate, transforming it from a two-dimensional static surface to a three-dimensional rotatable object. This additional rotational degree of freedom enables versatile color display by allowing the substrate to present different colors through rotation, while the pyramidal surface structure provides the optical variation needed for effective color shifting during rotation.

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

3Reliability

If pyramidal structures with multiple slanted faces are created, then color shift effect is enhanced during rotation, but manufacturing precision requirements increase

Engineering Contradiction:
Improveconsistency of color shift effectVSAvoidprecision of pyramidal structure
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The pyramidal structures are designed with uniform geometry and consistent coating across all faces. This homogeneity ensures that each pyramid behaves predictably during rotation, providing consistent color shift effects. By making all pyramidal elements identical and uniformly coated, the invention achieves reliable and repeatable color shifting behavior, reducing the impact of manufacturing variations on overall performance.

Inventive Principle:
Principle #33Homogeneity

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 enables a visually appealing and dynamic color shift effect by rotation, with optimal color travel observed as the substrate rotates, achieving a strong color shift without requiring differences in dielectric thickness across faces, and allowing for secure and encoded visual patterns.

Implementation Method 1

optically variable color-shifting coating... exhibit the property of changing color upon variation of the angle of incident light, or as the viewing angle of the observer is shifted

Methodology Applied
Scientific EffectOptical interference: Interference

Implementation Method 2

the faces of the structures are substantially planar and/or may have a diffraction grating formed therein

Methodology Applied
Scientific EffectDiffraction: Diffraction

Data Source

PatentEP1990210B2Structured surfaces that exhibit color by rotation
Publication Date: 2021.12.22 VIAVI SOLUTIONS INC(US)
  • EP1990210B2 patent drawingFigure 1
  • EP1990210B2 patent drawingFigure 2
  • EP1990210B2 patent drawingFigure 3

AI summary

An optically variable device is disclosed having a substrate with an array of pyramidal structures formed upon it or within it. The structures are coated with an optically variable color-shifting coating. Each of the structures form a pyramidal-like having at least three slanted faces and wherein one or more colors seen when viewing the pyramids vary as substrate is rotated at least 30 degrees about an axis orthogonal to the substrate. In order to see a color shift the device is rotated around the surface normal of the substrate, while keeping the angle of incidence to the light source the same, and keeping the viewing angle the same. Various forms of pyramids may be used, however pyramids with planar faces are most suitable.