3m Innovative Properties Company

Madeleine B Fleming

Kenneth L Smith

John C Nelson

John F Dreyer

Nelson D Sewall

David W Meitz

The invention relates to articles comprising a sheeting having a microstructured surface that reflects light in a moir&#xe9;-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).

Retroreflective articles having moire-like pattern

The invention relates to methods of making a master and replicas thereof including tooling and retroreflective sheeting. The invention further relates to the corresponding master, tooling and in particular retroreflective sheeting. The 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 substantially the same size throughout the array. The master as well as corresponding tooling and sheeting preferably have an average 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 an average groove spacing of less than about 0.004 inches (0.1016 mm).

Methods of making a master and replicas thereof

Retroreflective articles provide varying retroreflection using a first surface that includes a plurality of light redirecting structures and a second surface that includes retroreflective areas and separation areas. The light redirecting structures on the first surface are preferably arranged relative to the retroreflective areas and the separation areas on the second surface such that a substantial portion of light incident on the light redirecting structures is superimposed on areas of the second surface. At some angles, it is preferred that substantially all of the light is superimposed on either the retroreflective areas or the separation areas, resulting in varying retroreflection from the retroreflective articles. Together, the two optical surfaces of the retroreflective articles provide varying retroreflection of incident light where the variations can be between, e.g., retroreflection or no retroreflection, retroreflection of different colors, retroreflection at different brightness levels, etc. In other words, when subjected to incident light from a steady light source, relative movement between the retroreflective article and the light source will result in variations in retroreflection. When retroreflective articles provide varying retroreflection, the variations or changes will tend to increase the conspicuity of an object or person on which the retroreflective article is located.

Retroreflectors having two optical surfaces and varying retroreflectivity

Retroreflective articles provide modulating retroreflection using a front surface that includes at least first and second areas having different transmission characteristics and a back surface that includes retroreflective areas and separation areas. The first and second areas on the front surface are arranged relative to the retroreflective areas and the separation areas on the back surface such that a substantial portion of light incident on the first areas of the front surface at a first angle is transmitted through the first areas of the front surface to the retroreflective areas on the back surface where it is retroreflected back through the front surface. In addition, a substantial portion of light incident on the first areas of the front surface at a second angle is transmitted through the first areas on the front surface to the separation areas. Together, the front and back surfaces manipulate light such that the retroreflective articles provide modulating retroreflection of incident light where the modulation or variation can be between, e.g., retroreflection or no retroreflection, retroreflection of different colors, retroreflection at different brightness levels, etc. In other words, when subjected to incident light from a steady light source, relative movement between the retroreflective article and the light source can result in variations or modulation in the retroreflection of light from the light source. When retroreflective articles provide modulating retroreflection, the variations or changes tend to increase the conspicuity of the retroreflective articles.

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Lake Elmo, MN, United States of America

Madeleine B Fleming