Non-reflective graphic surface

• US 4,883,341 A
• Filed: 03/17/1988
• Issued: 11/28/1989
• Est. Priority Date: 04/24/1987
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: TIR Systems Limited (Koninklijke Philips N.V.)
• Inventors: Whitehead, Lorne A.
• Primary Examiner(s): Arnold, Bruce Y.
• Assistant Examiner(s): Gass, Rebecca D.
• Application Number:
  US07/169,292
• Time in Patent Office: 621 Days
• Field of Search: 350/276 R, 350/452, 350/451, 350/167, 350/286
• US Class Current: 359/601
• CPC Class Codes: G02B 3/08 with discontinuous faces, e.g. Fresnel lens diffractive Fresnel lenses G02B5/1876
• CPC Class Codes: G02B 5/0231 the surface having microprismatic or micropyramidal shape macroscopic prism arrays G02B5/045
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02B 5/0294 adapted to provide an additional optical effect, e.g. anti-reflection or filter
• CPC Class Codes: G02B 5/045 Prism arrays

Abstract

A graphic surface display device comprises a graphic surface be displayed and a cover of substantially transparent material overlying and in optical contact with the graphic surface. The cover has a minutely textured outer surface such that the angle between a first vector normal to a randomly selected point on the cover'"'"'s surface; and, a second vector which passes through the selected point and which is normal to a plane tangential to the graphic surface at the point of intersection of the second vector with the graphic surface; has substantially unity probability of exceeding 45°.

Claims

1. A graphic surface display device, comprising:

(a) a graphic surface to be displayed; and

,

(b) a cover of substantially transparent material overlying said graphic surface, said cover having a minutely textured outer surface wherein an angle φ

₁ between;

(i) a first vector normal to a randomly selected point on said outer surface; and

,

(ii) a second vector which passes through said selected point and which is normal to a plane tangential to said graphic surface at the point of intersection of said second vector with said graphic surface;

has substantially unity probability of exceeding 45°

.

2. A graphic surface display as defined in claim 1, wherein said cover is an optical contact with said graphic surface.

3. A graphic surface display device as defined in claim 2, wherein said cover is removably optically contactible with said graphic surface.

4. A graphic surface display device as defined in claim 2, wherein said cover comprises an array of parallel, longitudinal prisms.

5. A graphic surface display device as defined in claim 4, wherein said prisms are right angle prisms.

6. A graphic surface display device as defined in claim 4, wherein the height of said prisms exceeds about 50 times the wavelength of light.

7. A graphic surface display device as defined in claim 4, wherein:

(a) said prisms have apices of average width "e"; and

,

(b) e/a is less than about 0.02, where "a" is the height of said prisms.

8. A graphic surface display device as defined in claim 4, wherein the height of said prisms exceeds about 0.1 mm.

9. A graphic surface display device as defined in claim 4, wherein said cover further comprises a substrate of thickness "b" between said prisms and said graphic surface.

10. A graphic surface display device as defined in claim 9, wherein "b" is about 0.15 inches.

11. A graphic surface display device as defined in claim 9, wherein a+b is less than about 0.5 mm., where "a" is the height of said prisms.

12. A graphic surface display device as defined in claim 9, wherein said substrate is removably optically contactible with said graphic surface.

13. A graphic surface display device as defined in claim 4, wherein said prisms have a base of about 0.07 inches and a height of about 0.03 inches.

14. A graphic surface display device as defined in claim 1, wherein said outer surface is textured such that the probability distribution of said angle for points on said outer surface:

(a) is substantially 0 if said angle is less than 45°

;

(b) has a maximum value at a selected angle; and

,

(c) is substantially 0 for angles which differ from said selected angle by more than a selected deviation angle of less than about 10°

.

15. A graphic surface display device as defined in claim 14, wherein the average vertical displacement from the bottoms of recesses in said surface, to the apices of protrusions from said surface, exceeds about 50 times the wavelength of light.

16. A graphic surface display device as defined in claim 14, wherein:

(a) protrusions from said outer surface have apices of average width "e"; and

,

(b) e/a is less than about 0.02, where "a" is the average vertical displacement from the bottoms of recesses in said outer surface to the apices of said protrusions.

17. A graphic surface display device as defined in claim 14, wherein the average vertical displacement from the bottoms of recesses in said outer surface, to the apices of protrusions from said outer surface, exceeds about 0.1 mm.

18. A graphic surface display device as defined in claim 14, wherein said cover further comprises a substrate of thickness "b" between said outer surface and said graphic surface.

19. A graphic surface display device as defined in claim 18, wherein a+b is less than about 0.5 mm., where "a" is the average vertical displacement from the bottoms of recesses in said outer surface to the apices of protrusions from said outer surface.

20. A graphic surface display device is defined in claim 18, wherein said cover substrate is removably optically contactible with said graphic surface.

21. A graphic surface display device as defined in claim 1, said cover further comprising a minutely textured inner surface wherein an angle φ

₂ between;

(i) third vector normal to a randomly selected point on said inner surface; and

,

(ii) a fourth vector which passes through aid selected inner surface point and which is normal to a plane tangential to said graphic surface at the point of intersection of said fourth vector with said graphic surface;

is greater than or equal to;

space="preserve" listing-type="equation">45°

+1/2(φ

.sub.min -sin .sup.-1 ((1/n) sin φ

.sub.min))

wherein "n" is the refractive index of said material, and φ

_min is the greatest angle for which it is true for substantially all points on said outer surface that φ

₁ >

φ

_min.

22. A graphic surface display device as defined in claim 21, wherein said inner and outer surfaces each comprises an array of parallel, longitudinal prisms.

23. A graphic surface display device as defined in claim 22, wherein the sides of each one of said prisms is inclined at an angle of about 63°

with respect to a plane beneath said one prism and tangential to said graphic surface.

24. A window comprising a substantially transparent material having minutely textured, first and second surfaces on opposed sides of a notional reference surface, wherein an angle φ

₁ between;

(i) a first vector normal to a randomly selected point of said first surface; and

,

(ii) a second vector which passes through said selected point and which is normal to a plane tangential to said reference surface at the point of intersection of said second vector with said reference surface;

has substantially unity probability of exceeding 45°

; and

wherein an angle φ

₂ between;

(iii) a third vector normal to a randomly selected point on said second surface; and

,

(iv) a fourth vector which passes through said selected second surface point and which is normal to a plane tangential to said reference surface at the point of intersection of said fourth vector with said reference surface;

is greater than or equal to;

space="preserve" listing-type="equation">4°

+1/2 (φ

.sub.min -sin .sup.-1 ((1/n) sin φ

.sub.min))

where "n" is the refractive index of said material, where φ

_min is the greatest for which it is true for substantially all points on said first surface that φ

₁ >

φ

_min.

25. A window as defined in claim 24, wherein said first and second surfaces each comprise an array of parallel, longitudinal prisms.

26. A window as defined in claim 25, wherein the sides of each one of said prisms is inclined at an angle of about 63°

with respect to a plane beneath said one prism and tangential to said reference surface.

27. A window as defined in claim 24, wherein said surfaces are textured such that the probability distribution of either of said angles φ

₁ or φ

₂ for points on said surfaces;

(a) is substantially 0 if said angle is less than 45°

;

(b) has a maximum value at a selected angle; and

,

(c) is substantially 0 for angles which differ from said selected angle by more than a selected deviation angle of less than about 10°

.