Reflective film

• US 4,799,137 A
• Filed: 03/24/1987
• Issued: 01/17/1989
• Est. Priority Date: 03/24/1987
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Aho, Kenneth A.
• Primary Examiner(s): Lazarus, Ira S.
• Assistant Examiner(s): Hagarman, Sue
• Application Number:
  US07/030,033
• Time in Patent Office: 665 Days
• Field of Search: 362/299, 362/301, 362/303, 362/304, 362/309, 362/327, 362/347, 362/348, 362/349, 362/339, 362/31, 362/255, 362/256, 350/286, 428/912.2, 428/167, 428/30, 428/458, 428/913
• US Class Current: 362/309
• CPC Class Codes: F21S 43/30 characterised by reflectors
• CPC Class Codes: F21S 43/40 characterised by the combination of reflectors and refractors
• CPC Class Codes: F21V 7/00 Reflectors for light sources characterised by cooling arrangements F21V29/505
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G09F 13/14 Arrangements of reflectors therein

Abstract

A light transmissive film having a smooth surface and a structured surface. The structured surface has a series of triangular prisms running parallel or concentric to one another. A reflector is placed adjacent to the smooth surface so that light entering the film at an angle which is close to parallel to the smooth surface will emerge from the film at a predetermined angle with respect to the incoming beam. A light fixture utilizing the film is also disclosed.

Claims

1. A light reflecting film formed of a transparent material, said film comprising first and second major surfaces, said first surface being a structured surface forming a plurality of triangular prisms, each of said prisms having first and second faces and said prisms forming a plurality of peaks and grooves and said second surface being second surface such that light entering one of said prisms through said prism'"'"'s first face at less than a predetermined angle with respect to said second surface will be totally internally reflected by said prism'"'"'s second face reflected by said light reflecting means and will emerge from said film through a different one of said prisms.

2. A light reflecting film of claim 1 wherein said light reflecting means is metal which has been deposited on said second surface.

3. The light reflecting film of claim 1 wherein said prisms are right isosceles prisms the perpendicular sides of said prisms making 45°

angles with said second surface.

4. The light reflecting film of claim 3 wherein said transparent material is a polymer material.

5. The light reflecting film of claim 4 wherein said light reflecting means is metal which has been deposited on said second surface.

6. The light reflecting film of claim 1 wherein said prisms are straight and parallel to one another.

7. The light reflecting film of claim 1 wherein said prisms are circular and concentric.

8. A light fixture comprising:

a light reflecting film having first and second major surfaces, said first surface being a structured surface having a plurality of triangular prisms, each of said prisms having an axis, said axes of said prisms running parallel to one another, and said second surface being smooth, and a first light reflecting means adjacent to said second surface for reflecting light approaching said second surface from said first surface; and

light emitting means on a first end of said film for illuminating said film, said light emitting means being positioned so that light rays approach said film in a direction which is almost parallel to said second surface of said film.

9. The light fixture of claim 8 wherein said light emitting means is positioned so that light rays approach said film in a direction which makes an angle of no more than 20°

with said second surface.

10. The light fixture of claim 8 wherein said light emitting means is positioned so that light rays approach said film in a direction which is perpendicular to said axes of said prisms.

11. The light fixture of claim 8 further comprising a second light reflecting means on a second end of said film for reflecting light emitted by said light emitting means toward said film if said light has passed said film without striking it.

12. The light fixture of claim 11 wherein said light emitting means is positioned so that light rays approach said film in a direction which makes an angle of no more than 20°

with said second surface.

13. The light fixture of claim 12 wherein said light emitting means is positioned so that light rays approach said film in a direction which is perpendicular to said axes of said prisms.