Light control device

• US 6,398,370 B1
• Filed: 11/15/2000
• Issued: 06/04/2002
• Est. Priority Date: 11/15/2000
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Gaides, Gary E., Sano, Koichi, Humpal, Paul E., Chiu, Raymond C.
• Primary Examiner(s): Dang, Hung Xuan
• Assistant Examiner(s): TRA, TUYEN Q
• Application Number:
  US09/713,066
• Time in Patent Office: 566 Days
• Field of Search: 359/601, 359/614, 359/613, 428/168, 428/172, 428/201, 428/206, 428/207, 428/913, 428/163, 428/167
• US Class Current: 359/613
• CPC Class Codes: G02B 5/003 Light absorbing elements
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
• CPC Class Codes: Y10T 428/2457 Parallel ribs and/or grooves
• CPC Class Codes: Y10T 428/24612 Composite web or sheet

Abstract

A light control device is disclosed that includes a two film construction, each film having a plurality of light absorbing regions. For example, the light absorbing elements can be a series of grooves or column-like indentations in the films that are filled or coated with a light absorbing material. The two films can be adjacently disposed so that their respective light absorbing regions form a plurality of light absorbing elements that extend along the thickness direction of the device. The light absorbing elements allow a viewer to view an image through the light control device within a range of viewing angles while blocking a view of the image outside that range of viewing angles. The two film construction allows for relative ease of manufacture as well as the ability to form light absorbing elements that can provide better viewing uniformity throughout a typical viewing range, a sharp privacy viewing cut off, and reduced ghost image formation.

Claims

1. A light control device comprising:

a first light transmissive film comprising a first plurality of light absorbing regions extending into a surface thereof; and

a second light transmissive film disposed adjacent the first light transmissive film and comprising a second plurality of light absorbing regions extending into a surface thereof,

wherein the first plurality of light absorbing regions and the second plurality of light absorbing regions are relatively positioned to allow a viewer to view an image through the light control device within a range of viewing angles and to block viewing of the image through the light control device outside the range of viewing angles.

2. The light control device of claim 1, wherein the first plurality of light absorbing regions comprises a plurality of grooves.

3. The light control device of claim 1, wherein the first and second plurality of light absorbing regions each comprise a plurality of grooves.

4. The light control device of claim 3, wherein the first and second plurality of light absorbing regions are mutually aligned.

5. The light control device of claim 1, wherein the first and second light transmissive films are substantially refractive index matched.

6. The light control device of claim 1, wherein the first and second light transmissive films are laminated together.

7. The light control device of claim 1, wherein the first and second light transmissive films are bonded together using an optical adhesive.

8. The light control device of claim 1, wherein the first plurality of light absorbing regions exhibit a refractive index that is about the same or greater than the refractive index of the first light transmissive film throughout a range of wavelengths in the visible spectrum.

9. The light control device of claim 1, wherein the first plurality of light absorbing regions exhibit wall angles greater than 5°

.

10. The light control device of claim 1, wherein the first plurality of light absorbing regions exhibit curved walls.

11. A process for making a light control device comprising the steps of:

forming a first light transmissive film having a first plurality of indentations extending into a surface thereof;

forming a second light transmissive film having a second plurality of indentations extending into a surface thereof;

rendering the first and second plurality of indentations light absorbing; and

adjacently disposing the first and second light transmissive films,

wherein when the light control device is positioned between an image and a viewer, the light control device is capable of allowing the viewer to view the image through the light control device within a range of viewing angles and to block viewing of the image through the light control device outside the range of viewing angles.

12. The process of claim 11, wherein the first and second plurality of indentations comprises a plurality of parallel grooves.

13. The process of claim 12, further comprising the step of mutually aligning the first and second plurality of indentations.

14. The process of claim 11, wherein the step of rendering the first and second plurality of indentations light absorbing comprises filling the first and second plurality of indentations with a visible light absorbing material.

15. The process of claim 11, wherein the step of adjacently disposing the first and second light transmissive films comprises laminating the first and second light transmissive films together.

16. The process of claim 15, wherein laminating is performed using an optical adhesive.

17. The process of claim 11, wherein the step of rendering the first and second plurality of indentations light absorbing is performed before the step of adjacently disposing the first and second light transmissive films.

18. The process of claim 11, wherein the step of rendering the first and second plurality of indentations light absorbing is performed after the step of adjacently disposing the first and second light transmissive films.