Dual groove set retroreflective cube corner article and method of manufacture

Claims

We claim:

1. 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 using only two sets of parallel grooves with each set comprising a plurality of grooves comprising optical surfaces arranged at side angles relative to a groove axis and to a base reference plane, and at least two of the grooves in at least one of the groove sets are at a different groove depth.

2. 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 using only two sets of parallel grooves with each set comprising a plurality of grooves comprising optical surfaces arranged at side angles relative to a groove axis and to a base reference plane, and at least two of the cube corner elements have different heights above a common reference plane.

3. 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 using only two sets of parallel grooves with each set comprising a plurality of grooves comprising optical surfaces arranged at side angles relative to a groove axis and to a base reference plane, and at least two of the cube corner elements are machined so that the size of the active apertures differ in both an x direction and a y direction at a non-zero entrance angle.

4. A retroreflective cube corner article which is a replica of a directly machined substrate in which a plurality of different geometric structures including cube corner elements having parallel bisectors are machined in the substrate using only two sets of parallel grooves with each set comprising a plurality of grooves comprising optical surfaces arranged at side angles relative to a groove axis and to a base reference plane.

5. The article of claim 4 in which at least two of the cube corner elements have symmetry axes which are non-parallel.

6. The article of claim 1, 2, 3 or 4 in which the spacing of grooves within at least one of the groove sets having at least three grooves is varied so that the spacing between a first groove and an adjacent second groove differs from the spacing between the second groove and an adjacent third groove.

7. 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 having parallel symmetry axes are machined in the substrate using only two sets of parallel grooves comprising optical surfaces arranged at side angles relative to a groove axis and to a base reference plane, and the spacing between a first groove and an adjacent second groove in a groove set differs from the spacing between the second groove and an adjacent third groove in the groove set.

8. The article of claim 1, 2, 3, 4 or 7 in which at least two of the cube corner elements have different lengths.

9. 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 using only two sets of parallel grooves comprising optical surfaces arranged at side angles relative to a groove axis and to a base reference plane, and the spacing in at least one of the groove sets is varied so that at least two of the cube corner elements have different lengths.

10. The article of claim 1, 2, 4, 7 or 9 which exhibits at least two different active aperture sizes at a non-zero entrance angle.

11. 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 using only two sets of parallel grooves comprising optical surfaces arranged at side angles relative to a groove axis and to a base reference plane, and at least two of the elements have opposing orientations of element non-retroreflective triangular faces.

12. The article of claim 11 in which the opposing non-retroreflective triangular faces share a common edge.

13. The article of claim 11 in which the elements having an opposing relationship are geometrically identical.

14. The article of claim 1, 2, 4, 7, 9 or 11 in which at least two of the cube corner elements have different heights above a common reference plane.

15. The article of claim 1, 2, 3, 4, 7, 9 or 11 in which a plurality of cube corner elements are at different heights, and a plurality of higher cube corner elements provide support for a sealing medium spaced above lower cube corner elements.

16. The article of claim 1, 2, 3, 4, 7, 9 or 11 in which at least one of the grooves in at least one of the groove sets defines geometric structures including cube corner elements having lateral faces which form boundary edges of a separation surface.

17. The article of claim 16 in which the article is partially light transmissive.

18. The article of claim 16 in which each of the separation surfaces, taken at any point along any surface in which it lays, has a curved cross section.

19. The article of claim 16 in which each of the separation surfaces, taken at any point along any surface in which it lays, has a flat cross section.

20. The article of claim 1, 2, 3, 4, 7, 9 or 11 comprising a structure selected from the group of structures including traffic control materials, retroreflective vehicle markings, directional reflectors, internally illuminated retroreflective articles, and retroreflective markings.

21. The article of claim 1, 2, 3, 4, 7, 9 or 11 comprising at least one groove side angle in at least one set of grooves which differs from the angle that would produce an orthogonal intersection with other faces of elements defined by the groove sides.

22. The article of claim 1, 2, 3, 4, 7, 9 or 11 in which at least one of the sets of grooves includes, in a repeating pattern, at least two groove side angles that differ from one another.

23. The article of claim 1, 2, 3, 4, 7, 9 or 11 in which at least one cube face is arcuate over a significant portion of the cube face to modify the shape of the retroreflected light pattern.

24. The article of claim 23 in which the shape of the arcuate face is concave.

25. The article of claim 23 in which the shape of the arcuate face is convex.

26. The article of claim 23 in which the shape of the arcuate face is substantially cylindrical, so that the axis of the cylinder is approximately parallel to the groove which bounds the arcuate face.

27. The article of claim 1, 2, 3, 4, 7, 9 or 11 in which the article is transparent.

28. The article of claim 1, 2, 3, 4, 7, 9 or 11 in which a portion of the article is reflectively coated.

29. The article of claim 1, 2, 3, 4, 7, 9 or 11 in which at least two cube corner elements share a common optical surface.

30. The article of claim 1, 2, 3, 4, 7, 9 or 11 in which at least one of the cube corner elements comprises a bisector which intersects a base reference plane at an angle other than 90.degree..

31. A retroreflective cube corner element composite sheeting comprising a plurality of zones of retroreflective cube corner elements, each zone comprising a replica of a directly machined substrate in which a plurality of cube corner elements are machined, the composite sheeting comprising at least one zone in which at least two geometric structures including cube corner elements are formed from two sets of parallel grooves, the geometric structures having different heights above a common reference plane.

32. A retroreflective cube corner element composite sheeting comprising a plurality of zones of retroreflective cube corner elements, each zone comprising a replica of a directly machined substrate in which a plurality of cube corner elements are machined, and the composite sheeting comprising at least one zone in which the grooves are formed from two sets of parallel grooves and at least two of the grooves in at least one of the groove sets are at a different groove depth.

33. A retroreflective cube corner element composite sheeting comprising a plurality of zones of retroreflective cube corner elements, each zone comprising a replica of a directly machined substrate in which a plurality of cube corner elements are machined, and the composite sheeting comprising at least one zone in which at least two geometric structures including cube corner elements are machined using two sets of grooves so that the size of the active apertures differ at a non-zero entrance angle.

34. The sheeting of claim 32 or 33 in which at least one zone comprises at least two cube corner elements which have different heights above a common reference plane.

35. The sheeting of claim 31, 32 or 33 which exhibits asymmetric entrance angularity.

36. The sheeting of claim 31, 32 or 33 which exhibits symmetric entrance angularity.

37. The sheeting of claim 33 in which the size of the active apertures differ in both an x direction and a y direction.

38. A retroreflective cube corner element composite sheeting comprising a plurality of zones of retroreflective cube corner elements, each zone comprising a replica of a directly machined substrate in which a plurality of cube corner elements are machined, and the composite sheeting comprising at least one zone in which a plurality of geometric structures including cube corner elements are formed using two groove sets.

39. The sheeting of claim 38 in which all of the cube corner elements in at least one of the zones formed using two groove sets have parallel bisector axes.

40. The sheeting of claim 38 in which at least two of the cube corner elements in at least one of the zones formed using two groove sets have opposing orientations of element non-retroreflective triangular faces.

41. A retroreflective cube corner element composite sheeting comprising a plurality of zones of retroreflective cube corner elements, each zone comprising a replica of a directly machined substrate in which a plurality of cube corner elements are machined, and the composite sheeting comprising at least one zone formed using two sets of parallel grooves in which the spacing of grooves within at least one of the groove sets varies so that at least two of the cube corner elements have different lengths.

42. The sheeting of claim 32, 33, 34, 38 or 41 in which the spacing of grooves within at least one of the groove sets is varied so that the spacing between a first groove and an adjacent second groove differs from the spacing between the second groove and an adjacent third groove.

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. Divergence profile, design flexibility, and optical performance 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 comprises a method of machining a cube corner article. The method includes the steps of directly machining two groove sets each comprising at least two grooves into a substrate to produce a plurality of geometric structures including cube corner elements, and configuring at least two of the grooves in at least one of the sets at a different groove depth.

The invention comprises a method of machining a cube corner article. The method includes the steps of directly machining two groove sets each comprising at least two grooves into a substrate to produce a plurality of geometric structures including cube corner elements, and configuring at least two of the cube corner elements so that each has a different height above a common reference plane.

The invention comprises a method of machining a cube corner article. The method includes the steps of directly machining two groove sets each comprising at least two grooves into a substrate to produce a plurality of geometric structures including cube corner elements, and configuring at least two of the cube corner elements so that the size of the active apertures differ in both an x and y direction at a non-zero entrance angle.

The invention comprises a method of machining a cube corner article. The method includes the steps of directly machining two groove sets each comprising at least two grooves into a substrate to produce a plurality of different geometric structures including cube corner elements, and configuring the groove sets so that the cube corner elements have parallel bisectors.

The invention comprises a method of machining a cube corner article. The method includes the steps of directly machining two groove sets each comprising at least two grooves into a substrate to produce a plurality of geometric structures including cube corner elements having parallel symmetry axes, and varying the spacing of grooves within at least one of the groove sets so that the spacing between a first groove and an adjacent second groove differs from the spacing between the second groove and an adjacent third groove.

The invention comprises a method of machining a cube corner article. The method includes the steps of directly machining two groove sets each comprising at least two grooves into a substrate to produce a plurality of geometric structures including cube corner elements, and varying the spacing of grooves within at least one of the groove sets so that at least two of the cube corner elements have different lengths.

The invention comprises a method of machining a cube corner article. The method includes the steps of directly machining two groove sets each comprising at least two grooves into a substrate to produce a plurality of geometric structures including cube corner elements, and arranging at least two of the elements to have opposing orientations of element non-retroreflective triangular faces.

The invention comprises 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 using only two sets of parallel grooves, and at least two of the grooves in at least one of the groove sets are at a different groove depth.

The invention comprises 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 using only two sets of parallel grooves, and at least two of the cube corner elements have different heights above a common reference plane.

The invention comprises 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 using only two sets of parallel grooves, and at least two of the cube corner elements are machined so that the size of the active apertures differ in both an x and y direction at a non-zero entrance angle.

The invention comprises a retroreflective cube corner article which is a replica of a directly machined substrate in which a plurality of different geometric structures including cube corner elements having parallel bisectors are machined in the substrate using only two sets of parallel grooves.

The invention comprises 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 having parallel symmetry axes are machined in the substrate using only two sets of parallel grooves. The spacing between a first groove and an adjacent second groove in a groove set differs from the spacing between the second groove and an adjacent third groove in the groove set.

The invention comprises 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 using only two sets of parallel grooves. The spacing in at least one of the groove sets is varied so that at least two of the cube corner elements have different lengths.

The invention comprises 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 using only two sets of parallel grooves. At least two of the elements have opposing orientations of element non-retroreflective triangular faces.

The invention comprises a retroreflective cube corner element composite sheeting comprising a plurality of zones of retroreflective cube corner elements. Each zone comprises a replica of a directly machined substrate in which a plurality of cube corner elements are machined. the composite sheeting comprises at least one zone in which at least two geometric structures including cube corner elements are formed from two sets of parallel grooves. The geometric structures have different heights above a common reference plane.

The invention comprises 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 machined. The composite sheeting comprises at least one zone in which the grooves are formed from two sets of parallel grooves and at least two of the grooves in at least one of the groove sets are at a different groove depth.

The invention comprises a retroreflective cube corner element composite sheeting comprising a plurality of zones of retroreflective cube corner elements. Each zone comprises a replica of a directly machined substrate in which a plurality of cube corner elements are machined. The composite sheeting comprising at least one zone in which at least two geometric structures including cube corner elements are machined using two sets of grooves so that the size of the active apertures differ at a non-zero entrance angle.

The invention comprises a retroreflective cube corner element composite sheeting comprising a plurality of zones of retroreflective cube corner elements. Each zone comprises a replica of a directly machined substrate in which a plurality of cube corner elements are machined. The composite sheeting comprising at least one zone in which a plurality of geometric structures including cube corner elements are formed using two groove sets.

The invention comprises a retroreflective cube corner element composite sheeting comprising a plurality of zones of retroreflective cube corner elements. Each zone comprises a replica of a directly machined substrate in which a plurality of cube corner elements are machined. The composite sheeting comprising at least one zone formed using two sets of parallel grooves in which the spacing of grooves within at least one of the groove sets varies so that at least two of the cube corner elements have different lengths.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a known two groove set directly machined array.

FIG. 2 is a section view of the array taken along line 2--2 in FIG. 1.

FIG. 3 is an end view of the array taken along line 3--3 in FIG. 1.

FIG. 4 is a plan view of a known two groove set directly machined array.

FIG. 5 is a section view of the array taken along line 5--5 in FIG. 4.

FIG. 6 is an end view of the array taken along line 6--6 in FIG. 4.

FIG. 7 is a section view of an array similar to that shown in FIG. 4 including a canted cube corner element.

FIG. 8 is a plan view of a portion of a directly machined dual groove set array having variable spacing between grooves.

FIG. 9 is a section view taken along line 9--9 in FIG. 8.

FIG. 10 is a section view taken along line 10--10 in FIG. 8.

FIG. 11 is a view at a 60.degree. entrance angle of some of the active apertures of the array shown in FIGS. 8-10.

FIG. 12 is a plan view of a portion of a directly machined dual groove set array having variable spacing between grooves and variable length.

FIG. 13 is a side view of the array of FIG. 12.

FIG. 14 is a plan view of a portion of a directly machined dual groove set array having variable spa