Patterned pavement markings with upright retroreflectors
AssigneeMinnesota Mining and Manufacturing Company
InventorsThomas P. Hedblom, T. Ian Bradshaw
Life of this patent
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Abstract
An improved pavement marking sheet material, and a method for making such pavement marking sheet material. The pavement marking sheet material comprises a selected configuration of upright retroreflectors. The upright retroreflectors are arranged in a selected configuration so as to maximize reflectivity as measured at actual observation geometries by allowing light to be incident to effective portions of the retroreflective elements on the upright retroreflectors.
Claims43
A pavement marking sheet material comprising a continuous polymeric base sheet having a plurality of upright retroreflectors on its upper surface, said upright retroreflectors comprising retroreflective elements,
- said upper surface being made up of a plurality of segments arranged in a selected manner,
- each said segment having a front edge, a rear edge, and two side edges, and having an array of a plurality of said upright retroreflectors positioned along said front edge and a spacing zone that is free of said upright retroreflectors along said rear edge, the longitudinal length L of said spacing zone being determined by the formula L>H/tan(90.degree.-.theta.), where H is the height of the upright retroreflectors and .theta. is a design entrance angle that falls within the range of 86.9.degree. to 89.9.degree.;
- said marking material comprising a plurality of segments arranged with the front edge of a segment abutting the rear edge of an adjacent segment.
A pavement marking sheet material comprising a substrate having a base surface and a structured surface opposite said base surface, said structured surface including:
- a first retroreflection zone including at least one .retroreflector;
- a spacing zone adjacent said first retroreflection zone, said spacing zone having a length, L, extending along a longitudinal axis of said material determined by the formula L>H/tan(90.degree.-.theta.), where H is the height of the upright retroreflectors and .theta. is a design entrance angle that falls within the range of 86.9.degree. to 89.9.degree.;
- and
- a second retroreflection zone adjacent said spacing zone, said second retroreflection zone comprising at least one retroreflector.
A pavement marking sheet material comprising a substrate having a base surface and a structured surface opposite said base surface, said structured surface including a plurality of retroreflection zones separated by spacing zones, wherein:
- each retroreflection zone includes a plurality of retroreflectors arranged to form an array of adjacent retroreflectors;
- and
- each spacing zone has a length L extending along a longitudinal axis of said material determined by the formula L>H/tan(90.degree.-.theta.), where H is the height of the upright retroreflectors and .theta. is a design entrance angle that fails within the range of 86.9.degree. to 89.9.degree., said spacing zone being substantially free of retroreflective elements.
Dependencies are inferred from the claim text.