Lamina comprising cube corner elements and retroreflective sheeting

• US 7,556,386 B2
• Filed: 10/31/2007
• Issued: 07/07/2009
• Est. Priority Date: 03/06/2003
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Smith, Kenneth L.
• Primary Examiner(s): Cherry; Euncha P
• Application Number:
  US11/931,193
• Publication Number:
  US 20080049327A1
• Time in Patent Office: 615 Days
• Field of Search: 359/529, 359/530, 264/1.1, 264/1.6, 264/1.9
• US Class Current: 359/530
• CPC Class Codes: B29C 59/007 Forming single grooves or ribs, e.g. tear lines, weak spots by moulding B29C37/0057; folding lines B29C53/06; in metal articles B21D17/00; by cutting B26D3/08
• CPC Class Codes: B29D 11/00605 Production of reflex reflectors
• CPC Class Codes: B29L 2011/0091 Reflex reflectors
• CPC Class Codes: G02B 1/10 Optical coatings produced by application to, or surface treatment of, optical elements G02B1/08 takes precedence
• CPC Class Codes: G02B 1/18 Coatings for keeping optical surfaces clean, e.g. hydrophobic or photo-catalytic films G02B1/16 takes precedence
• CPC Class Codes: G02B 5/122 cube corner, trihedral or triple reflector type
• CPC Class Codes: G02B 5/124 plural reflecting elements forming part of a unitary plate or sheet
• CPC Class Codes: Y10T 156/1082 Partial cutting bonded sandwich [e.g., grooving or incising]
• CPC Class Codes: Y10T 428/2457 Parallel ribs and/or grooves

Abstract

The present invention is directed to lamina(e) comprising cube corner elements, a tool comprising an assembly of laminae and replicas thereof. The invention further relates to retroreflective sheeting.

Claims

1. Retroreflective sheeting comprising an array of preferred geometry cube corner elements wherein at least one cube comprises a 1-2 dihedral angle error and a 1-3 dihedral angle error varied in opposition and the sheeting exhibits an average brightness at 0°

and 90°

orientation according to ASTM D4596-1a of at least 375 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 0.5°

.

2. The sheeting of claim 1 wherein the cube comprises dihedral angle errors having magnitudes between 1 arc minute and 60 arc minutes.

3. The sheeting of claim 1 wherein the elements are in a row having dihedral edges that range from being nominally parallel to nonparallel by less than 1°

.

4. The sheeting of claim 1 wherein the dihedral angle errors are varied in a repeating pattern.

5. The retroreflective sheeting of claim 1 wherein the average brightness is at least 400 candelas/lux/m².

6. The retroreflective sheeting of claim 1 wherein the average brightness is at least 450 candelas/lux/m².

7. The retroreflective sheeting of claim 1 wherein the sheeting further comprises a seal film.

8. The retroreflective sheeting of claim 1 wherein the sheeting further comprises a specular reflective coating.

13. The sheeting of claim 1 wherein the average brightness is at least 400 candelas/lux/m².

14. The sheeting of claim 1 wherein the average brightness is at least 450 candelas/lux/m².

15. The sheeting of claim 1 wherein the sheeting further comprises a seal film.

16. The sheeting of claim 1 wherein the sheeting further comprises a specular reflective coating.

9. Retroreflective sheeting comprising a row of preferred geometry cube corner elements wherein a plurality of elements in the row have three dihedral angle errors that are different from each other and the sheeting exhibits an average brightness at 0°

and 90°

orientation according to ASTM D4596-1a of at least 375 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 0.5°

.

10. The sheeting of claim 9 wherein the dihedral angle errors have magnitudes between 1 arc minute and 60 arc minutes.

11. The sheeting of claim 9 comprising a plurality of the elements in a row wherein at least one dihedral edge of the elements range from being nominally parallel to nonparallel by less than 1°

.

12. The sheeting of claim 9 wherein the dihedral angle errors of the elements are varied in a repeating pattern.

17. Retroreflective sheeting comprising an array of preferred geometry cube corner elements wherein the elements have a lateral dimension of less than 0.04 inches and the sheeting exhibits an average brightness at 0°

and 90°

orientation according to ASTM D4596-1a of at least 375 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 0.5°

.

18. The sheeting of claim 17 wherein the elements have a lateral dimension of less than 0.02 inches.

19. The sheeting of claim 17 wherein the elements have a lateral dimension of less than 0.007 inches.

20. The retroreflective sheeting of claim 17 wherein the average brightness is at least 400 candelas/lux/m².

21. The retroreflective sheeting of claim 17 wherein the average brightness is at least 450 candelas/lux/m².

22. The retroreflective sheeting of claim 17 wherein the sheeting further comprises a seal film.

23. The retroreflective sheeting of claim 17 wherein the sheeting further comprises a specular reflective coating.

24. Retroreflective sheeting comprising an array of preferred geometry cube corner elements interconnected by a continuous land layer wherein the land layer has a thickness between 0.001 and 0.100 inches and the sheeting exhibits an average brightness at 0°

and 90°

orientation according to ASTM D4596-1a of at least 375 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 0.5°

.

25. The sheeting of claim 24 wherein the land layer has a thickness between 0.003 and 0.10 inches.

26. The sheeting of claim 24 wherein the elements and land layer comprise the same material.

27. The sheeting of claim 24 wherein the average brightness is at least 450 candelas/lux/m².

28. The sheeting of claim 24 wherein the sheeting further comprises a seal film.

29. The sheeting of claim 24 wherein the sheeting further comprises a specular reflective coating.