Light control film
The present disclosure provides a light control film that is capable of transmitting light, or allowing a viewer to observe information, only within a viewing region centered around the normal (perpendicular line) to a surface. The light control film generally blocks information or light outside of this viewing region, and provides security in all directions including right-and-left and up-and-down of the film. The light control film includes a plurality of light-transmissive cavities that are surrounded by a light absorbing material, such that each of the plurality of cavities is optically isolated from adjacent cavities. Each of the light-transmissive cavities effectively block light which enters the cavity outside of a viewing (that is, cutoff) angle.
1. A light control film, comprising:
a first major surface and an opposing second major surface;
a light absorptive material extending between the first and second major surfaces; and
a plurality of optically-isolated light transmissive cavities at least partially extending between the first and second major surfaces,
wherein each of the plurality of cavities comprise a first aperture coincident with the first major surface, a second aperture adjacent the second major surface, and at least one side wall extending between the first aperture and the second aperture, and further
wherein the second aperture and the second major surface are separated by the light absorptive material having a land thickness greater than 0.1 microns.
2. The light control film of claim 1 , wherein a cross-section of each of the cavities parallel to the first major surface comprises a circular shape, an oval shape, or a polygonal shape.
3. The light control film of claim 1 , wherein the side wall intersects a perpendicular to the first major surface at an angle between about 0 degrees and about 10 degrees.
4. The light control film of claim 1 , wherein each of the plurality of optically-isolated light transmissive cavities have a depth D between the first and second apertures, a first aperture width W1 and a second aperture width W2 associated with a viewing plane orthogonal to the first major surface, and D/((W1+W2)/2) is at least 1.25 and D/((W1+W2)/2) is not greater than 8.25 in the viewing plane.
5. The light control film of claim 1 , wherein the land thickness is between 0.1 microns and about 10 microns.
6. The light control film of claim 1 , further comprising an optically transmissive film disposed adjacent at least one of the first major surface and the second major surface.
7. The light control film of claim 6 , wherein the optically transmissive film further comprises an adhesive.
8. The light control film of claim 6 , wherein the optically transmissive film comprises at least one of polycarbonate, polyethylene terephthalate, polyethylene naphthalate, high density polyethylene, low density polyethylene, and linear low density polyethylene.
9. The light control film of claim 1 , wherein each cavity is filled with an optically transparent material.
10. The light control film of claim 9 , wherein the optically transparent material comprises air, a transparent polymer, or a transparent adhesive.
11. The light control film of claim 9 , wherein the optically transparent material has a refractive index that is lower than the absorptive material refractive index.
12. The light control film of claim 1 , wherein the light absorptive material comprises a curable resin and a colorant.
13. The light control film of claim 12 , wherein the curable resin comprises a radiation curable resin.
14. The light control film of claim 12 , wherein the curable resin is selected from the group consisting of acrylic-based resins derived from epoxies, polyesters, polyethers, and urethanes; ethylenically unsaturated compounds; aminoplast derivatives having at least one pendant acrylate group; polyurethanes (polyureas) derived from an isocyanate and a polyol (or polyamine); isocyanate derivatives having at least one pendant acrylate group; epoxy resins other than acrylated epoxies; and mixtures and combinations thereof.
15. The light control film of claim 12 , wherein the colorant comprises a pigment or a dye.
16. The light control film of claim 12 , wherein the colorant comprises carbon black, fuchsin, carbazole violet, or Foron Brilliant Blue.
17. The light control film of claim 1 , wherein the side wall further comprises a coating.
18. The light control film of claim 17 , wherein the coating comprises a reflective material.
19. A display device comprising the light control film of claim 1 .
20. A window film comprising the light control film of claim 1 .