US 9,810,817 B2
Light directing film and method for making the same
Alan B. Campbell, Santa Rosa, CA (US); Dale L. Ehnes, Cotati, CA (US); John F. Van Derlofske, III, Minneapolis, MN (US); Mark R. Dupre, Oakdale, MN (US); Stephen J. Dreyer, North St. Paul, MN (US); Patrick H. Marushin, Sartell, MN (US); Todd M. Johnson, St. Paul, MN (US); and Bryan V. Hunt, Nowthen, MN (US)
Assigned to 3M INNOVATIVE PROPERTIES COMPANY, Saint Paul, MN (US)
Appl. No. 12/934,855
Filed by Alan B. Campbell, Santa Rosa, CA (US); Dale L. Ehnes, Cotati, CA (US); John F. Van Derlofske, III, Minneapolis, MN (US); Mark R. Dupre, Oakdale, MN (US); Stephen J. Dreyer, North St. Paul, MN (US); Patrick H. Marushin, Sartell, MN (US); Todd M. Johnson, St. Paul, MN (US); and Bryan V. Hunt, Nowthen, MN (US)
PCT Filed Apr. 1, 2009, PCT No. PCT/US2009/039077
§ 371(c)(1), (2), (4) Date Mar. 25, 2011,
PCT Pub. No. WO2009/124107, PCT Pub. Date Oct. 8, 2009.
Prior Publication US 2011/0199697 A1, Aug. 18, 2011
Int. Cl. G02B 5/04 (2006.01); F21V 8/00 (2006.01); G02F 1/1335 (2006.01)
CPC G02B 5/045 (2013.01) [G02B 6/0053 (2013.01); G02F 1/133615 (2013.01); G02F 2001/133607 (2013.01)] 32 Claims
OG exemplary drawing
 
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 α1, and
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 α2 the same as α1, 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.