Retroreflective articles having moire-like pattern

US6935756B2 · kind B2 · utility

Assignee

• 3M INNOVATIVE PROPERTIES COMPANY · US

Inventors

• Nelson D. Sewall · Forest Lake, US
• Kenneth L. Smith · White Bear Lake, US
• David W. Meitz · Windom, US
• Madeleine B. Fleming · Oakdale, US
• John C. Nelson · Healdsburg, US

Key dates

• Filing date: Jun 11, 2002
• Grant date: Aug 30, 2005
• Expiry date: Nov 3, 2022

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B27/60
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

The invention relates to articles comprising a sheeting having a microstructured surface that reflects light in a moiré-like pattern. The invention further relates to methods of making a master and replicas thereof including tooling that results in sheeting having such pattern. A preferred method comprises forming V-shaped grooves in a substrate (e.g. metal plate) wherein the intersections of three grooves form cube-corner elements. The cube-corner elements are formed in such a manner that adjacent parallel grooves have substantially the same groove spacing and groove depth throughout the array. The master as well as corresponding tooling and sheeting preferably have a groove spacing within the range of about 0.0005 inches (0.0127 mm) to about 0.007 inches (0.1778 mm) throughout the array and more preferably a groove spacing of less than about 0.004 inches (0.1016 mm).