Two-sided corner-cube retroreflectors and methods of manufacturing the same

• US 7,703,931 B2
• Filed: 03/19/2009
• Issued: 04/27/2010
• Est. Priority Date: 03/02/2007
• Status: Expired due to Fees

• Current Assignee: Technology Solutions And Invention, LLC
• Original Assignee: Technology Solutions & Invention, LLC
• Inventors: Nilsen, Robert B.
• Primary Examiner(s): Phan; James
• Application Number:
  US12/407,313
• Publication Number:
  US 20090237791A1
• Time in Patent Office: 404 Days
• Field of Search: None
• US Class Current: 359/530
• CPC Class Codes: G02B 5/124 plural reflecting elements forming part of a unitary plate or sheet

Abstract

In a retroreflective sheeting, and methods of formation thereof, the sheeting comprises a body of material, the body having a first surface and a second surface. A plurality of first full-square-sided corner-cube structures are on the first surface of the body, the first full-square-sided corner-cube structures each having three facets that lie along planes that are orthogonal to each other. A plurality of second full-square-sided corner-cube structures are on the second surface of the body, the second full-square-sided corner-cube structures each having three facets that lie along planes that are orthogonal to each other. The body is constructed and arranged to be transparent to incident electromagnetic energy at a range of wavelengths and to have a thickness so that an incident electromagnetic energy ray that is incident at one of the first and second surfaces enters the body, and is redirected by both the first surface and the second surface so that both the first surface and the second surface contribute to retroreflection of the incident electromagnetic energy ray, and exits from the one of the first and second surfaces at which the incident electromagnetic energy ray was incident to emit a retroreflected electromagnetic energy ray of the incident electromagnetic energy ray.

Claims

1. A linear retroreflector that retroreflects electromagnetic energy, comprising:

a body of material, the body having a first surface and a second surface;

a plurality of first linear prism structures on the first surface of the body, the first linear prism structures each having two facets that extend along planes that are substantially orthogonal to each other; and

a plurality of second linear prism structures on the second surface of the body, the second linear prism structures each having two facets that lie along planes that are substantially orthogonal to each other;

the body being constructed and arranged to be transparent to incident electromagnetic energy at a range of wavelengths and to have a thickness so that an incident electromagnetic energy ray that is incident at one of the first and second surfaces enters the body, and is redirected by both the first surface and the second surface so that both the first surface and the second surface contribute to retroreflection of the incident electromagnetic energy ray, and exits from the one of the first and second surfaces at which the incident electromagnetic energy ray was incident to emit a retroreflected electromagnetic energy ray of the incident electromagnetic energy ray, wherein the body is further constructed and arranged so that an incident electromagnetic energy ray that is incident at one of the first and second surfaces enters the body by refraction, exits the other of the first and second surfaces by refraction, reenters the other of the first and second surfaces by refraction, and exits from the one of the first and second surfaces at which the incident electromagnetic energy ray was incident to emit a retroreflected electromagnetic energy ray of the incident electromagnetic energy ray.

2. The linear retroreflector of claim 1 wherein the incident electromagnetic energy ray that is incident at one of the first and second surfaces enters the body by refraction, is internally reflected by the other of the first and second surfaces, and exits from the one of the first and second surfaces at which the incident electromagnetic energy ray was incident to emit a retroreflected electromagnetic energy ray of the incident electromagnetic energy ray.

3. The linear retroreflector of claim 1 wherein at least a portion of the facets of the linear prism structures of the first surface and the facets of the linear prism structures of the second surface are substantially parallel, wherein proud apexes of the first linear prism structures substantially align with recessed apexes of the second linear prism structures and wherein proud apexes of the second linear prism structures substantially align with recessed apexes of the first linear prism structures in a vertical direction of the body.

4. The linear retroreflector of claim 1 wherein at least a portion of the facets of the linear prism structures of the first surface and the facets of the linear prism structures of the second surface are parallel and wherein proud apexes of the first linear prism structures and recessed apexes of the second linear prism structures and proud apexes of the second linear prism structures and recessed apexes of the first linear prism structures are offset relative to each other in a horizontal direction of extension of the body.

5. The linear retroreflector of claim 1, wherein the first and second linear prism structures comprise at least one of open-faced linear prism structures and solid linear prism structures.

6. The linear retroreflector of claim 1 wherein the plurality of first linear prism structures and the plurality of second linear prism structures are each arranged in an array having a pitch that relates to a distance between neighboring linear prism structures and wherein exit locations of the retroreflected electromagnetic energy ray are spaced apart from an entry location of the incident electromagnetic energy ray by a distance greater than the pitch of the array.

7. The linear retroreflector of claim 6 wherein the body thickness is selected so that the exit location of the retroreflected electromagnetic energy ray is located at a linear prism structure that is different and spaced apart from a linear prism structure at which an entrance location of the incident electromagnetic energy ray is positioned.

8. The linear retroreflector of claim 6 wherein the body thickness is selected so that the entry location of the incident electromagnetic energy ray and the exit location of the retroreflected electromagnetic energy ray are positioned in a same linear prism structure.

9. The linear retroreflector of claim 6 wherein the body thickness is selected so that at certain entry locations, the incident electromagnetic energy ray enters the body by refraction at the one of the first and second surfaces, and exits from the other of the first and second surfaces by refraction so that the incident electromagnetic energy ray is transmitted through the body and not retroreflected.

10. The retroreflector of claim 1 further comprising a wavelength-selective optical coating or a wavelength-selective color coating on a subset of at least one of the first and second linear prism structures.

11. The retroreflector of claim 10 wherein the optical coating includes a specular coating.

12. The retroreflector of claim 11 wherein the specular coating comprises a material comprising at least one of a metal layer and one or more dielectric layers.

13. The retroreflector of claim 1 wherein the material of the body is selected from the group consisting of thermoplastic and thermoset polymers, glass and ceramic, that are at least one of:

transparent to incident electromagnetic energy, wavelength-selective transparent to incident electromagnetic energy, or opaque to incident electromagnetic energy.

14. The retroreflector of claim 13 wherein the polymers further include a filler that is selected from the group consisting of:

glass, carbon, ceramic, graphite, polymers, and metals.

15. The retroreflector of claim 1 wherein the body comprises an intermediate substrate and first and second top layers on opposed sides of the substrate, wherein the substrate comprises a material that is wavelength-selective transparent to the incident electromagnetic energy.

16. The retroreflector of claim 15 wherein the intermediate substrate has a wavelength-selective transparent coating applied to at least one surface thereof.

17. The retroreflector of claim 15 wherein the intermediate substrate, the first and second top layers, and boundaries therebetween are configured to be wavelength-selective transparent to incident electromagnetic energy at the range of wavelengths.

18. The retroreflector of claim 1 further comprising an encapsulating material that surrounds the body of material of the retroreflector.

19. The retroreflector of claim 1 wherein a subset of at least one of the plurality of first linear prism structures and plurality of second linear prism structures includes flats in the regions of recessed apexes of the subset of linear prism structures, the flats comprising a material that at least partially fills the subset of linear prism structures.

20. The retroreflector of claim 19 wherein the material of the flats comprises one of:

a material that is integral with the material of the body and a material that is applied to the material of the body.

21. The retroreflector of claim 19 wherein the flats are at an acute angle relative to a horizontal plane of the sheeting.

22. The retroreflector of claim 19 wherein the subset of the plurality of first linear prism structures and plurality of second linear prism structures are configured so that the body of the material in the region of the subset forms a retroreflective structure that operates as a linear truncated corner-cube structure to incident electromagnetic energy.

23. The retroreflector of claim 22 wherein the retroreflective structure that operates as a linear truncated corner-cube structure is configured to include:

a flat on the first surface;

a proud apex on the second surface comprising neighboring facets of adjacent open-faced second linear prism structures; and

a portion of the body of material between the flat on the first surface and the proud apex on the second surface.

24. The retroreflector of claim 23 wherein the linear truncated corner-cube structure operates as a full-square-sided linear truncated corner-cube structure to incident electromagnetic energy.

25. The retroreflector of claim 1 wherein a subset of the first or second linear prism structures have recessed apexes that include modified surfaces, including at least one of flattened recessed apexes, flattened recessed apexes having marking features, recessed apexes having curved surfaces, recessed apexes having segmented surfaces, and recessed apexes having microstructured surfaces.

26. The retroreflector of claim 1 wherein a subset of the first or second linear prism structures have proud apexes that include modified surfaces, including at least one of flattened proud apexes, flattened proud apexes having marking features, proud apexes having curved surfaces, proud apexes having segmented surfaces, and proud apexes having microstructured surfaces.

27. The retroreflector of claim 1 wherein a subset of the first or second linear prism structures have facets that include modified surfaces, including marking features, curved surfaces, segmented surfaces, and microstructured surfaces.

28. The retroreflector of claim 1 wherein the first linear prism structures are arranged along a first axis and wherein the second linear prism structures are arranged along a second axis, and wherein the first and second axes are parallel to each other.

29. The retroreflector of claim 1 wherein the first linear prism structures are arranged along a first axis and wherein the second linear prism structures are arranged along a second axis, and wherein the first and second axes lie at an acute angle relative to each other.

30. The retroreflector of claim 1 wherein a first region of at least one of the plurality of first linear prism structures and the plurality of second linear prism structures is arranged along a first axis and wherein a second region of the at least one of the plurality of first linear prism structures and the plurality of second linear prism structures is arranged along a second axis and wherein the first and second axes of the first and second regions lie at an acute angle with respect to each other.

31. The retroreflector of claim 1 wherein the plurality of first linear prism structures and the plurality of second linear prism structures are each arranged in an array having a pitch that relates to a distance between neighboring linear prism structures, and wherein a first pitch of the first linear prism structures is different than a second pitch of the second linear prism structures.

32. The retroreflector of claim 1 wherein the plurality of first linear prism structures and the plurality of second linear prism structures are each arranged in an array having a pitch that relates to a distance between neighboring linear prism structures, and wherein a first pitch of a first region of the first linear prism structures is different than a second pitch of the second region of the first linear prism structures or wherein a first pitch of a first region of the second linear prism structures is different than a second pitch of a second region of the second linear prism structures.

33. The retroreflector of claim 1 wherein the body of material in a first region of the retroreflector has a first thickness that is different than a second thickness in the second region of the body of material.

34. A linear retroreflector that retroreflects electromagnetic energy, comprising:

a body of material, the body having a first surface and a second surface;

a plurality of first linear prism structures on the first surface of the body, the first linear prism structures each having two facets that extend along planes that are substantially orthogonal to each other; and

a plurality of second linear prism structures on the second surface of the body, the second linear prism structures each having two facets that lie along planes that are substantially orthogonal to each other;

the body being constructed and arranged to be transparent to incident electromagnetic energy at a range of wavelengths and to have a thickness so that an incident electromagnetic energy ray that is incident at one of the first and second surfaces enters the body, and is redirected by both the first surface and the second surface so that both the first surface and the second surface contribute to retroreflection of the incident electromagnetic energy ray, and exits from the one of the first and second surfaces at which the incident electromagnetic energy ray was incident to emit a retroreflected electromagnetic energy ray of the incident electromagnetic energy ray, wherein the plurality of first linear prism structures and the plurality of second linear prism structures are each arranged in an array having a pitch that relates to a distance between neighboring linear prism structures and wherein exit locations of the retroreflected electromagnetic energy ray are spaced apart from an entry location of the incident electromagnetic energy ray by a distance greater than the pitch of the array.

35. The linear retroreflector of claim 34, wherein the body thickness is selected so that the exit location of the retroreflected electromagnetic energy ray is located at a linear prism structure that is different and spaced apart from a linear prism structure at which an entrance location of the incident electromagnetic energy ray is positioned.

36. The linear retroreflector of claim 34, wherein the body thickness is selected so that the entry location of the incident electromagnetic energy ray and the exit location of the retroreflected electromagnetic energy ray are positioned in a same linear prism structure.

37. The linear retroreflector of claim 34 wherein the body thickness is selected so that at certain entry locations, the incident electromagnetic energy ray enters the body by refraction at the one of the first and second surfaces, and exits from the other of the first and second surfaces by refraction so that the incident electromagnetic energy ray is transmitted through the body and not retroreflected.

38. A linear retroreflector that retroreflects electromagnetic energy, comprising:

a body of material, the body having a first surface and a second surface;

a plurality of first linear prism structures on the first surface of the body, the first linear prism structures each having two facets that extend along planes that are substantially orthogonal to each other; and

a plurality of second linear prism structures on the second surface of the body, the second linear prism structures each having two facets that lie along planes that are substantially orthogonal to each other, wherein a subset of at least one of the plurality of first linear prism structures and plurality of second linear prism structures includes flats in the regions of recessed apexes of the subset of linear prism structures, the flats comprising a material that at least partially fills the subset of linear prism structures;

the body being constructed and arranged to be transparent to incident electromagnetic energy at a range of wavelengths and to have a thickness so that an incident electromagnetic energy ray that is incident at one of the first and second surfaces enters the body, and is redirected by both the first surface and the second surface so that both the first surface and the second surface contribute to retroreflection of the incident electromagnetic energy ray, and exits from the one of the first and second surfaces at which the incident electromagnetic energy ray was incident to emit a retroreflected electromagnetic energy ray of the incident electromagnetic energy ray.

39. The retroreflector of claim 38, wherein the material of the flats comprises one of:

a material that is integral with the material of the body and a material that is applied to the material of the body.

40. The retroreflector of claim 38, wherein the flats are at an acute angle relative to a horizontal plane of the sheeting.

41. The retroreflector of claim 38, wherein the subset of the plurality of first linear prism structures and plurality of second linear prism structures are configured so that the body of the material in the region of the subset forms a retroreflective structure that operates as a linear truncated corner-cube structure to incident electromagnetic energy.

42. The retroreflector of claim 41, wherein the retroreflective structure that operates as a linear truncated corner-cube structure is configured to include:

a flat on the first surface;

a proud apex on the second surface comprising neighboring facets of adjacent open-faced second linear prism structures; and

a portion of the body of material between the flat on the first surface and the proud apex on the second surface.

43. The retroreflector of claim 42, wherein the linear truncated corner-cube structure operates as a full-square-sided linear truncated corner-cube structure to incident electromagnetic energy.