Light control material

• US 5,503,902 A
• Filed: 03/02/1994
• Issued: 04/02/1996
• Est. Priority Date: 03/02/1994
• Status: Expired due to Term

• Current Assignee: Printpack Illinois, Inc. (Printpack Holdings Incorporated)
• Original Assignee: Applied Physics Research, L.P.
• Inventors: Hurt, Mark J., Steenblik, Richard A.
• Primary Examiner(s): Loney, Donald J.
• Application Number:
  US08/204,489
• Time in Patent Office: 762 Days
• Field of Search: 428/167, 428/172, 428/178, 428/156, 428/166, 428/68, 428/137, 428/141, 428/143, 428/913, 430/13, 430/14, 430/16
• US Class Current: 428/172
• CPC Class Codes: B41M 3/14 Security printing securities B42D25/29
• CPC Class Codes: G03C 5/08 Photoprinting G03C5/18 takes precedence; Processes and means for preventing photoprinting
• CPC Class Codes: G03F 1/68 Preparation processes not covered by groups G03F1/20 - G03F1/50
• CPC Class Codes: G03F 7/0005 Production of optical devices or components in so far as characterised by the lithographic processes or materials used therefor
• CPC Class Codes: G03G 21/043 by using an original which is not reproducible or only reproducible with a different appearence, e.g. originals with a photochromic layer or a colour background
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/24479 including variation in thickness
• CPC Class Codes: Y10T 428/24612 Composite web or sheet

Abstract

A light control material for displaying black-and-white and color images by forming light traps in a layer of photopolymer at selected locations. The photopolymer layer constitutes a master from which embossments can be produced. An embossment which displays the image can be produced from the master by a soft embossing procedure. The light traps are formed in the master by reactively ion etching a layer of cured photopolymer at selected locations to create fields of tapered structures. An embossment generated from the master contains fields of tapered structures which correspond to those created in the master. The surface of the embossment which includes the fields of tapered structures is coated with a reflective material such as metal. Light which enters the fields is reflected within the fields of tapered structures until substantially all of the light has been absorbed. Light which does not enter the fields is reflected. The light traps correspond to the black areas of a black-and-white image whereas the reflective areas correspond to the white areas of the black- and-white image.

Claims

1. A light control material comprising:

a polymer layer having at least one light trap formed therein wherein said at least one light trap is comprised of a plurality of tapered structures which have relatively high aspect ratios and wherein said tapered structures are covered with a reflective material such that light entering said at least one light trap is reflected within said at least one light trap among the tapered structures until substantially all of the light which has entered said at least one light trap has been absorbed.

2. A light control material according to claim 1 wherein said at least one light trap is created by reactively ion etching said polymer layer to thereby form the tapered structures and by coating said tapered structures with metal to form said reflective layer.

3. A light control material according to claim 1 wherein said light control material is an embossment generated from a master by a soft embossing procedure.

4. A light control material for displaying a black-and-white image, said light control material comprising:

a polymer layer having a plurality of reflective areas and light traps formed therein, each of said light traps comprising a plurality of tapered structures, wherein said tapered structures have relatively high aspect ratios and wherein said reflective areas and said light traps are covered with a reflective material whereby light impinging on the reflective areas is reflected and light entering the light traps is reflected within the light traps among the tapered structures until substantially all of the light which has entered the light traps has been absorbed.

5. A light control material for displaying a black-and-white image according to claim 4 wherein said light control material is an embossment generated from a master by a soft embossing procedure and wherein said light traps formed in said embossment correspond to light traps formed in said master.

6. A light control material for displaying a black-and-white image according to claim 4 wherein said light traps are created by reactively ion etching said polymer layer to thereby form the tapered structures and by coating said tapered structures with metal to form said reflective layer.

7. A light control material for displaying a black-and-white image according to claim 5 wherein the light traps formed in the master are formed in selected locations in the master, and wherein said locations are selected in accordance with a photographic negative.

8. A light control material for displaying a black-and-white image according to claim 5 wherein the light traps formed in the master are formed in selected locations in said master, wherein said locations are selected in accordance with a computer-generated mask.

9. A light control material for displaying a color image, said light control material comprising:

a polymer layer having a plurality of reflective areas and light traps formed therein, each of said light traps comprising a plurality of tapered structures, wherein said tapered structures have relatively high aspect ratios and wherein said reflective areas and said light traps are covered with a reflective material whereby light impinging on the reflective areas is reflected and light entering the light traps is reflected within the light traps among the tapered structures until substantially all of the light which has entered the light traps has been absorbed, and wherein said polymer layer displays a black-and-white image, wherein the light traps provide the black in the black-and-white image and wherein the reflective areas provide the white in the black-and-white image; and

at least one color transparency overlaying said polymer layer, wherein said color transparency converts the black-and-white image into a color image.

10. A light control material for displaying a color image according to claim 9 wherein said light control material is an embossment generated from a master by a soft embossing procedure and wherein said light traps formed in said embossment correspond to light traps formed in said master.

11. A light control material for displaying a color image according to claim 10 wherein the light traps formed in the master are formed in selected locations in said master, wherein said locations are selected in accordance with a photographic negative.

12. A light control material for displaying a color image according to claim 10 wherein the light traps formed in the master are formed in selected locations in said master, wherein said locations are selected in accordance with a computer-generated mask.

13. A light control material for displaying a color image, said light control material comprising:

a polymer layer having a plurality of reflective areas and light traps formed therein, each of said light traps comprising a plurality of tapered structures, wherein said tapered structures have relatively high aspect ratios and wherein said reflective areas and said light traps are covered with a reflective material whereby light impinging on the reflective areas is reflected and light entering the light traps is reflected within the light traps among the tapered structures until substantially all of the light which has entered the light traps has been absorbed, and wherein said polymer layer displays a black-and-white image, wherein the light traps provide the black in the black-and-white image and wherein the reflective areas provide the white in the black-and-white image and wherein said polymer layer is overprinted with transparent color ink, and wherein said color transparent ink converts the black and white image into a color image.

14. A light control material for displaying a color image according to claim 13 wherein said light control material is an embossment generated from a master by a soft embossing procedure and wherein said light traps formed in said embossment correspond to light traps formed in said master.

15. A light control material for displaying a color image according to claim 14 wherein the light traps formed in the master are formed in selected locations in said master, wherein said locations are selected in accordance with a photographic negative.

16. A light control material for displaying a color image according to claim 14 wherein the light traps formed in the master are formed in selected locations in said master, wherein said locations are selected in accordance with a computer-generated mask.

17. A light control material for displaying a black-and-white image, said light control material comprising:

a substantially clear substrate having a surface on which light traps are formed in selected locations, wherein each of said light traps is comprised of a plurality of tapered structures, wherein said tapered structures have relatively high aspect ratios and wherein light entering the light traps is reflected within the light traps among the tapered structures until substantially all of the light which has entered the light traps has been absorbed.

18. A light control material for displaying a black-and-white image according to claim 17 wherein at least said light traps are covered with a reflective material.

19. A light control material for displaying a black-and-white image according to claim 17 wherein said surface and said light traps are covered with a reflective material.