Light control film with reduced ghost images

• US 5,254,388 A
• Filed: 12/20/1991
• Issued: 10/19/1993
• Est. Priority Date: 12/21/1990
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Melby, Jeffrey J., Theirl, Scott G.
• Primary Examiner(s): Ryan, Patrick J.
• Assistant Examiner(s): Bahta, Abraham
• Application Number:
  US07/820,611
• Time in Patent Office: 669 Days
• Field of Search: 428/120, 428/163, 428/167, 428/168, 428/170, 428/212, 428/218, 430/12, 430/23
• US Class Current: 428/120
• CPC Class Codes: G02B 27/0018 with means for preventing ghost images anti-reflection coatings G02B1/11
• CPC Class Codes: G02B 5/00 Optical elements other than lenses light guides G02B6/00; optical logic elements G02F3/00
• CPC Class Codes: G02B 5/005 Diaphragms for cameras G03B9/02
• CPC Class Codes: H01J 2229/8913 Anti-reflection, anti-glare, viewing angle and contrast improving treatments or devices
• CPC Class Codes: H01J 29/89 Optical or photographic arrangements structurally combined or co-operating with the vessel H01J29/866 and H01J29/868 take precedence
• CPC Class Codes: H04N 5/65 Holding-devices for protective discs or for picture masks
• CPC Class Codes: Y10T 428/24182 Inward from edge of web or sheet
• CPC Class Codes: Y10T 428/24537 Parallel ribs and/or grooves
• CPC Class Codes: Y10T 428/2457 Parallel ribs and/or grooves
• CPC Class Codes: Y10T 428/24579 with particulate matter
• CPC Class Codes: Y10T 428/24595 and varying density
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/24992 Density or compression of components

Abstract

A louvered plastic film has louvers including central regions with a relatively high coefficients of extinction and outer regions with relatively low coefficients of extinction. Such a film provides a dramatic reduction in ghost images.

Claims

1. A louvered plastic film comprising a plurality of clear regions separated by louvers wherein each of said louvers has a central region having a first coefficient of extinction and an outer region adjacent said clear region having a second coefficient of extinction, said first coefficient of extinction being at least 1.5 times said second coefficient of extinction.

2. The louvered plastic film of claim 1 wherein said louvers are of a clear material with a light absorbing material incorporated therein.

3. The louvered plastic film of claim 2 wherein said light absorbing material is carbon black.

4. The louvered plastic film of claim 2 wherein both said clear regions and said louvers are of cellulose acetate butyrate.

5. The louvered plastic film of claim 4 wherein said light absorbing material is carbon black.

6. The louvered plastic film of claim 5 wherein said outer regions of said louvers are in the range 0.12 to 1.0 percent by weight carbon black.

7. The louvered plastic film of claim 4 wherein said central regions of said louvers are in the range 1.5 to 10.0 percent by weight carbon black.

8. The louvered plastic film of claim 1 wherein said film has a thickness in the range 0.08 mm to 1.5 mm.

9. The louvered plastic film of claim 8 wherein said clear regions have widths in the range 0.05 mm to 1.0 mm.

10. The louvered plastic film of claim 8 wherein said outer regions of said louvers have widths in the range 0.0025 mm to 0.015 mm.

11. The louvered plastic film of claim 8 wherein said central regions of said louvers have widths in the range 0.005 mm to 0.03 mm.

12. The louvered plastic film of claim 8 wherein said louvers are of a clear material with a light absorbing material incorporated therein.

13. The louvered plastic film of claim 12 wherein both said clear regions and said louvers are of cellulose acetate butyrate.

14. The louvered plastic film of claim 13 wherein said light absorbing material is carbon black.

15. The louvered plastic film of claim 14 wherein said clear regions have widths in the range 0.05 mm to 1.0 mm, said outer regions of said louvers have widths in the range 0.0025 mm to 0.015 mm and said central regions of said louvers have widths in the range 0.005 mm to 0.03 mm.

16. The louvered plastic film of claim 15 wherein said outer regions of said louvers are in the range 0.12 to 1.0 percent by weight carbon black and said central regions of said louvers are in the range 1.5 to 10.0 percent by weight carbon black.

17. The louvered plastic film of claim 15 wherein said film has a thickness in the range 0.08 mm to 0.6 mm, said clear regions have widths in the range 0.05 mm to 0.25 mm, said outer regions of said louvers have widths in the range 0.0025 mm to 0.01 mm and said central regions of said louvers have widths in the range 0.005 mm to 0.02 mm.

18. The louvered plastic film of claim 17 wherein said outer regions of said louvers are in the range 0.12 to 1.0 percent by weight carbon black and said central regions of said louvers are in the range 1.5 to 10.0 percent by weight carbon black.

19. A louvered plastic film according to claim 1 further comprising an antireflection coating.

20. A louvered plastic film according to claim 1 wherein said film has first and second major surfaces and said first major surface has a layer of glass adhered thereto.

21. A louvered plastic film according to claim 20 wherein said glass has an antireflection coating.

22. A louvered plastic film according to claim 20 wherein said second major surface has a layer of glass adhered thereto.

23. A louvered plastic film according to claim 22 wherein said layer of glass adhered to said second major surface has a neutral density coating.

24. A louvered plastic film according to claim 22 wherein said layer of glass adhered to said second major surface has an electrically conductive coating.

25. A louvered plastic film according to claim 24 wherein said electrically conductive coating has an electrical resistivity of less than 5000 Ohms per square.

26. A louvered plastic film according to claim 25 wherein said electrically conductive coating has an electrical resistivity of less than 500 Ohms per square.

27. A louvered plastic film according to claim 24 wherein said electrically conductive coating also serves as a neutral density coating.

28. A louvered plastic film according to claim 24 wherein said electrically conductive coating has an antireflection coating.

29. A louvered plastic film according to claim 28 wherein said layer of glass adhered to said first major surface has an antireflection coating.

30. A privacy screen for use with a cathode ray tube display said screen comprising louvered plastic film having a plurality of clear regions separated by louvers wherein each of said louvers has a central region having a relatively high coefficient of extinction and outer regions adjacent said clear regions having relatively low coefficients of extinction.