Light directing film and method for making the same
First Claim
1. A light directing film comprising a structured major surface, wherein the structured major surface comprises a plurality of microstructures, wherein at least a portion of the microstructures are linear and extend along a first direction, and wherein each microstructure comprises:
- first regions with a constant height along a second direction normal to the first direction and a first apex having first dihedral angle α
1, andsecond regions adjacent to the first regions, wherein the second regions have a non-constant height along the second direction and a maximum height greater than the constant height of the first regions and a second apex having a second dihedral angle α
2 the same as α
1, and wherein the second regions extend outwardly along a third direction normal to the first and the second directions such that the first regions and the second regions have the same lateral cross sectional shape; and
wherein the second regions are arranged on the structured major surface such that at least one of;
(1) the average density of the second regions on the structured major surface, (2) the average period of the second regions on the structured major surface, and (3) the height of the second regions relative to the height of the first regions, are sufficient to control the physical proximity of a second major surface to the structured major surface such that the second major surface contacts the second regions on the structured major surface and optical coupling between the structured major surface and the second major surface occurs primarily within the second regions.
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Accused Products
Abstract
A light directing film includes a structured major surface with a plurality of microstructures extending along a first direction. Each microstructure has a first region and a second region different from the first region, a substantially constant height in the first region and a non-constant maximum height in the second region greater than the substantially constant height in the first region, and a same lateral cross sectional shape in the first region and the second region.
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Citations
32 Claims
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1. A light directing film comprising a structured major surface, wherein the structured major surface comprises a plurality of microstructures, wherein at least a portion of the microstructures are linear and extend along a first direction, and wherein each microstructure comprises:
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first regions with a constant height along a second direction normal to the first direction and a first apex having first dihedral angle α
1, andsecond regions adjacent to the first regions, wherein the second regions have a non-constant height along the second direction and a maximum height greater than the constant height of the first regions and a second apex having a second dihedral angle α
2 the same as α
1, and wherein the second regions extend outwardly along a third direction normal to the first and the second directions such that the first regions and the second regions have the same lateral cross sectional shape; andwherein the second regions are arranged on the structured major surface such that at least one of;
(1) the average density of the second regions on the structured major surface, (2) the average period of the second regions on the structured major surface, and (3) the height of the second regions relative to the height of the first regions, are sufficient to control the physical proximity of a second major surface to the structured major surface such that the second major surface contacts the second regions on the structured major surface and optical coupling between the structured major surface and the second major surface occurs primarily within the second regions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A light directing article comprising
a first sheet of light directing film comprising a structured major surface, wherein the structured major surface comprises a plurality of linear microstructures extending along a first direction, and wherein each microstructure comprises: -
a first region having a first apex having first dihedral angle α
1, anda second region having a second apex having a second dihedral angle α
2 the same as α
1, wherein the second region is different from and adjacent to the first region, and wherein a microstructure has a substantially constant height along a second direction normal to the first direction in the first region and non-constant height along the second direction in the second region with a maximum height about 0.5 to about 3 microns greater than the substantially constant height in the first region, and wherein the second region extends outwardly along a third direction normal to the first and the second directions such that the first region and the second region have a same lateral cross sectional shape; anda second sheet of light directing film having a substantially planar surface and a structured surface opposite the substantially planar surface, wherein the substantially planar surface is adjacent the structured surface of the first sheet of light directing film, and wherein the structured surface of the second sheet of light directing film comprises a plurality of microstructures extending along a second direction approximately perpendicular to the first direction; and wherein the second regions of the structured surface of the first light directing film are arranged such that at least one of;
(1) the average density of the second regions on the structured major surface of the first sheet of light directing film, (2) the average period of the second regions on the structured major surface of the first sheet of the light directing film, and (3) the height of the second regions relative to the height of the first regions, are sufficient to cause optical coupling between the first and second sheets of light directing film to occur predominately in the second regions on the structured major surface of the first sheet of the light directing film.
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28. An optical display, comprising
a light source; -
a viewing screen; and a first light directing film that directs light from the light source to the viewing screen, wherein the first light directing film comprises; a first major surface; and a structured second major surface comprising a plurality of linear microstructures extending along a first direction, wherein each microstructure has a repeating pattern that comprises a first region and an adjacent second region, wherein; the first region has a constant height along a second direction normal to the first direction and a first apex having first dihedral angle α
1; andthe second region has a non-constant height along the second direction with a maximum height greater than the constant height of the first region and a second apex having a second dihedral angle α
2 the same as α
1, wherein the maximum height of the second regions is about 0.5 μ
m to about 3 μ
m greater than the constant height of the first regions, and wherein the repeating pattern has a density of at least 200 second regions per cm2, and wherein the second region extends outwardly along a third direction normal to the first and the second directions such that the first region and the second region have a same lateral cross sectional shape; anda second light directing film that directs light from the light source to the viewing screen, wherein at least one of;
(1) the maximum height of the second regions on the structured second major surface of the first light directing film, (2) the density of the second regions on the structured second major surface of the first light directing film, and (3) the average period of the second regions on the structured second major surface of the first light directing film, are sufficient such that optical coupling between the first light directing film and the second light directing film occurs primarily within the second regions on the structured second major surface of the first light directing film. - View Dependent Claims (29, 30)
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31. A method of making a light directing film, comprising:
- cutting a tool with a structured major surface, wherein the structured major surface comprises a plurality of grooves extending along a first direction, wherein each groove comprises;
a first region having a first apex having first dihedral angle α
1 and a second region having a second apex having a second dihedral angle α
2 the same as α
1, wherein the second region is different from and adjacent to the first region, anda constant height in the first region along a second direction normal to the first direction and a maximum height along the second direction in the second region greater than the constant height in the first region, wherein the second region extends outwardly along a third direction normal to the first and the second directions such that the first region and the second region have a same lateral cross sectional shape; and applying a polymeric material to the tool to form a film, wherein the film comprises a structured major surface with an arrangement of microstructures corresponding to the grooves in the tool, wherein the second regions on the structured major surface of the film are arranged such that at least one of;
(1) the average density of the second regions on the structured major surface, (2) the average period of the second regions on the structured major surface, and (3) the height of the second regions relative to the height of the first regions, are sufficient such that a major surface of a second film adjacent to the structured major surface of the film contacts the second regions of the structured major surface of the film and does not contact the first regions of the structured major surface of the film.
- cutting a tool with a structured major surface, wherein the structured major surface comprises a plurality of grooves extending along a first direction, wherein each groove comprises;
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32. A light directing film comprising a structured major surface, wherein the
structured major surface comprises a plurality of microstructures, wherein at least a portion of the microstructures are linear and extend along a first direction, and wherein the microstructures on the structured major surface comprise: -
a major amount of first regions with a constant height along a second direction normal to the first direction and a first apex having first dihedral angle α
1, anda minor amount second regions adjacent to the first regions, wherein the second regions have a non-constant height along the second direction and a maximum height greater than the constant height of the first regions and a second apex having a second dihedral angle α
2 the same as α
1, and wherein the second regions extend outwardly along a third direction normal to the first and the second directions such that the first regions and the second regions have the same lateral cross sectional shape; andwherein the second regions are randomly arranged on the structured major surface to limit the contact between a second major surface and the structured major surface to the second regions; wherein the second regions are arranged on the structured major surface such that at least one of;
(1) the average density of the second regions on the structured major surface, (2) the average period of the second regions on the structured major surface, and (3) the height of the second regions relative to the height of the first regions, are sufficient to control the physical proximity of the second major surface to the structured major surface such that the second major surface contacts the second regions on the structured major surface and optical coupling between the structured major surface and the second major surface occurs primarily within the second regions.
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Specification