US 12,228,818 B2
Back light unit for backlit displays
Kenneth L. Walker, Semora, NC (US); and Matthew K. Pope, Durham, NC (US)
Assigned to BrightView Technologies, Inc., Durham, NC (US)
Filed by BrightView Technologies, Inc., Durham, NC (US)
Filed on Jun. 4, 2024, as Appl. No. 18/733,419.
Application 18/733,419 is a division of application No. 18/418,311, filed on Jan. 21, 2024, granted, now 12,032,242.
Claims priority of provisional application 63/503,517, filed on May 22, 2023.
Prior Publication US 2024/0393639 A1, Nov. 28, 2024
Int. Cl. G02F 1/13357 (2006.01); G02F 1/1335 (2006.01)
CPC G02F 1/133603 (2013.01) [G02F 1/133605 (2013.01); G02F 1/133607 (2021.01); G02F 1/133611 (2013.01); G02F 1/13362 (2013.01); G02F 2202/022 (2013.01); G02F 2202/13 (2013.01)] 5 Claims
OG exemplary drawing
 
1. A back light unit comprising:
a) a two-dimensional array of light emitting diodes (LEDs), wherein a number of rows in the two-dimensional array is less than a number of columns in the two-dimensional array, at least one LED in the two-dimensional array producing light with an angular distribution of nominally ±90 degrees around a center of the at least one LED;
b) a transparent solid material layer positioned with a bottom surface over the two-dimensional array of LEDs, the transparent solid material layer configured to transform the light produced by the two-dimensional array of LEDs into light having an angular distribution of nominally less than ±90 degrees around the center of the at least one LED at a top surface of the transparent solid material layer;
c) a diffuser film positioned over the top surface of the transparent solid material layer, the diffuser film configured to provide a full width at half max of greater than 60 degrees and configured to diffuse the light produced at the top surface of the transparent solid material layer to produce diffused light at a top surface of the diffuser film;
d) a pair of cross brightness enhancement films positioned over the top surface of the diffuser film and comprising a plurality of prism microstructures on at least one surface, at least some prism microstructures having an apex angle of approximately ninety degrees; and
e) a polarizer reflector film positioned over the pair of cross brightness enhancement films and configured to transmit one polarization and to reflect another polarization, thereby improving uniformity of the light output from the back light unit.