摘要：
A device and method for providing diffuse emission of light through a flat surface, which includes a flat light guide having two larger flat surfaces on opposite sides and side surfaces, wherein one of the two larger flat surfaces being a light emitting surface and the other surface being a back surface, a connector for coupling light into said flat light guide, and a diffusing layer arranged in contact with at least one of said two larger flat surfaces of said flat light guide.
权利要求：
1. A device for providing diffuse emission of light through a flat surface, the device comprising: a flat light guide (1) having two larger flat surfaces on opposite sides and side surfaces, wherein one of the two larger flat surfaces being a light emitting surface (8) and the other surface being a back surface (9); a connector for coupling light into said flat light guide (1); and a diffusing layer (6) arranged in contact with said back surface (9) of said flat light guide (1); a first layer (2) arranged on top of said diffusing layer (6), wherein said first layer (2) has a refractive index which is lower than a refractive index of said flat light guide (1); and a second layer (7) covering said light emitting surface (8) having a refractive index which is lower than said refractive index of said flat light guide (1).
2. The device of claim 1, wherein a reflective material (3) is arranged on all sides of the flat light guide (1) apart from said light emitting surface (8).
3. The device of claim 2, wherein said reflective material (3) reflects light either through specular reflection or through diffuse reflection.
4. The device of any of claims 2 or 3, wherein the diffusing layer (6) is arranged between said back surface (9) and said reflective material (3).
5. The device of any one of claims 1 to 4, wherein the diffusing layer (6) has a refractive index higher than said flat light guide (1).
6. The device of any one of claims 1 to 5, wherein said diffusing layer (6) is printed on said back surface (9) of said flat light guide (1).
7. The device of any one of claims 1 to 6, wherein said diffusing layer (6) is arranged as a pattern (140) on said back surface (9) of said flat light guide (1) to provide a plurality of areas of diffuse reflection (11a-d) .
8. The device of claim 7, wherein said pattern (140) is printed as a plurality of areas of various widths and space between (11a-d).
9. The device of any one of claims 1 to 6, wherein said diffusing layer (6) comprises structures, such as microstructures, to diffuse the light, or wherein the diffusing layer (6) is a structural writing on said back surface (9) of said flat light guide (1).
10. The device of any one of claims 7 or 8, wherein said diffusing layer (6) is arranged as said pattern (140) on said back surface (9) of said flat light guide (1) and said reflective material (3) is reflecting light of areas of said back surface (9) not covered by said pattern (12a-d).
11. The device of any of claims 1 to 10, wherein said second layer (7) covering said light emitting surface (8) has a refractive index close to a material, such as human skin, to which light should be coupled.
12. The device of any one of claims 1 to 11, wherein an initial area closest to said connector is not covered by said diffusing material (6).
13. A method of manufacturing a device for providing diffuse emission of light through a flat surface, comprising: providing a flat light guide having two larger flat surfaces on opposite sides and side surfaces, wherein one of the two larger flat surfaces being a light emitting surface (8) and the other surface being a back surface (9); arranging a connector for coupling light into said flat light guide; and arranging a diffusing layer in contact with said back surface of said flat light guide; arranging a first layer (2) on top of said diffusing layer, wherein said first layer has a refractive index which is lower than a refractive index of said flat light guide; and arranging a second layer (7) covering said light emitting surface having a refractive index which is lower than a refractive index of said flat light guide.