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US 5,138,488 AGranted
Retroreflective material with improved angularity
AssigneeMinnesota Mining and Manufacturing Company
InventorTheodore J. Szczech
Life of this patent
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Abstract
The present invention provides an improved cube-corner retroreflective article that exhibits a wide range of retroreflective angularity in multiple viewing planes. The present invention provides cube-corner retroreflective elements having a decreased size, as measured by the height of the cube corner, thereby decreasing the amount of canting required to achieve a given angularity. Alternatively, angularity can be enhanced by leaving the degree of canting constant and decreasing the size of the cube corner.
Claims9
A retroreflective article comprising:
- at least one pair of cube-corner retroreflective elements, comprising three triangular and substantially mutually perpendicular lateral faces that meet at an apex, said mutually perpendicular lateral faces of each element being defined at their bases by linear edges that lie in a common base plane;
- adjacent pairs of said elements rotated 180 degrees with respect to one another;
- each retroreflective element having a height "h", measured from the base plane to the apex of the element along a line perpendicular to the base plane, h being less than about 150 .mu.m;
- and
- the optical axis of each element of the pair being tilted toward one edge of that element from the line perpendicular to said common base plane at an angle, alpha, wherein alpha is about 2.degree. to 5.degree..
2 more elements
Dependencies are inferred from the claim text.