US 12,292,648 B2
Optical sheet, backlight unit, liquid crystal display device, and information device
Chengheng Tsai, Tokyo (JP); Motohiko Okabe, Tokyo (JP); Takahiro Tsuji, Tokyo (JP); and Masayuki Sukigara, Tokyo (JP)
Assigned to KEIWA INCORPORATED, Tokyo (JP)
Filed by KEIWA Incorporated, Tokyo (JP)
Filed on Dec. 11, 2023, as Appl. No. 18/535,762.
Application 18/535,762 is a continuation of application No. 17/743,681, filed on May 13, 2022, granted, now 11,886,075.
Application 17/743,681 is a continuation of application No. 17/479,541, filed on Sep. 20, 2021, granted, now 11,360,350, issued on Jun. 14, 2022.
Application 17/479,541 is a continuation of application No. 16/927,753, filed on Jul. 13, 2020, granted, now 11,150,512, issued on Oct. 19, 2021.
Application 16/927,753 is a continuation of application No. PCT/JP2019/035235, filed on Sep. 6, 2019.
Prior Publication US 2024/0134226 A1, Apr. 25, 2024
Int. Cl. G02F 1/13357 (2006.01); G02F 1/1335 (2006.01)
CPC G02F 1/133606 (2013.01) [G02F 1/133603 (2013.01); G02F 1/133605 (2013.01); G02F 1/133607 (2021.01); G02F 1/133613 (2021.01)] 15 Claims
OG exemplary drawing
 
1. An optical sheet to be interposed between a plurality of small light sources and a prism sheet in a liquid crystal display device having the small light sources arranged in a dispersed manner at a side of the liquid crystal display device opposite to a display screen, wherein:
at least one surface of the optical sheet has unevenness, and
a total area of some of minute regions, which have surfaces inclined at inclination angles of 30° or more from an imaginary plane that is a flat surface appearing after imaginarily removing the unevenness, accounts for 30% or more of a total area of all the minute regions, for which the inclination angles are obtained by approximating the surfaces of the minute regions with the unevenness to flat surfaces, while two-dimensionally shifting the minute region with a projection area of 7.29 μm2 and a square shape with respect to the imaginary plane at equal intervals along the imaginary plane to obtain the minute regions at respective points on the imaginary plane until the number of the minute regions reaches 779,280.