Optical: systems and elements – Signal reflector – 3-corner retroreflective
Utility Patent
1999-10-21
2001-01-02
Phan, James (Department: 2872)
Optical: systems and elements
Signal reflector
3-corner retroreflective
C359S529000, C428S167000
Utility Patent
active
06168275
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to retroreflective cube corner element articles having prismatic retroreflective elements.
BACKGROUND OF THE INVENTION
Many types of retroreflective elements are known, including prismatic designs incorporating one or more geometric structures commonly known as cube corners. Retroreflective sheeting which employs cube corner type reflecting elements is well-known. Cube corner reflecting elements are trihedral structures which have three approximately mutually perpendicular lateral faces meeting in a single corner. Light rays are typically reflected at the cube faces due to either total internal reflection or reflective coatings. The manufacture of directly machined arrays comprising retroreflective cube corner elements has many inefficiencies and limitations. Percent active aperture, flexibility, and manufacturing ease are adversely affected by these limitations, and overall production costs versus performance are often higher relative to the new class of articles and methods of manufacture taught below.
SUMMARY OF THE INVENTION
The invention relates generally to a method of manufacturing a cube corner article comprising the steps of providing a machinable substrate of material suitable for forming reflective surfaces, and creating a plurality of geometric structures including cube corner elements in the substrate by directly machining at least two sets of parallel grooves in the substrate. The direct machining forms at least one geometric structure side surface having both an optical portion and a non-optical portion.
The invention also relates a method of machining a cube corner article comprising the steps of providing a directly machinable substrate in which a plurality of initial groove sets are machined to produce a plurality of geometric structures including cube corner elements, and adjusting the height of at least one of the geometric structures by directly machining at least one additional groove in at least one groove set.
The invention also relates a method of machining a cube corner article comprising the steps of providing a directly machinable substrate in which a plurality of groove sets are machined to produce a plurality of geometric structures including cube corner elements, and machining at least one of the grooves in each of at least two of the groove sets along partially overlapping paths in the substrate but at different depths of groove to form a final groove.
The invention also relates a retroreflective cube corner article which is a replica of a directly machined substrate in which a plurality of geometric structures including cube corner elements are machined in the substrate. At least one of the geometric structures is height adjusted by directly machining at least one additional groove in at least one groove set.
The invention also relates a retroreflective cube corner article which is a replica of a directly machined substrate in which a plurality of geometric structures including cube corner elements are machined in the substrate. Each geometric structure is bounded by at least one groove from each of at least two sets of parallel final grooves in the substrate, and at least one geometric structure comprises a side surface having both an optical portion and a non-optical portion.
The invention also relates a retroreflective cube corner element composite sheeting comprising a plurality of zones of geometric structures including retroreflective cube corner elements. Each zone comprises a replica of a directly machined substrate in which a plurality of initial groove sets are machined to produce a plurality of geometric structures including cube corner elements. The composite sheeting comprises at least one zone with height adjusted geometric structures including cube corner elements formed by directly machining at least one additional groove in at least one groove set.
The invention also relates a retroreflective cube corner element composite sheeting comprising a plurality of zones of geometric structures including retroreflective cube corner elements. Each zone comprises a replica of a directly machined substrate in which a plurality of cube corner elements are bounded in the substrate by a plurality of grooves from a plurality of groove sets. The composite sheeting comprises at least one zone with at least one geometric structure side surface having both an optical portion and a non-optical portion.
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Benson Gerald M.
Smith Kenneth L.
3M Innovative Properties Company
Jensen Stephen C.
Phan James
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