US 11,937,487 B2
Elliptically polarizing plate and organic light-emitting device
Sun Kug Kim, Daejeon (KR); Hyuk Yoon, Daejeon (KR); Seongho Ryu, Daejeon (KR); and Moon Su Park, Daejeon (KR)
Assigned to LG CHEM, LTD., Seoul (KR)
Appl. No. 16/982,896
Filed by LG CHEM, LTD., Seoul (KR)
PCT Filed Apr. 17, 2019, PCT No. PCT/KR2019/004624
§ 371(c)(1), (2) Date Sep. 21, 2020,
PCT Pub. No. WO2019/203562, PCT Pub. Date Oct. 24, 2019.
Claims priority of application No. 10-2018-0044315 (KR), filed on Apr. 17, 2018.
Prior Publication US 2021/0013276 A1, Jan. 14, 2021
This patent is subject to a terminal disclaimer.
Int. Cl. H10K 59/50 (2023.01); G02B 5/30 (2006.01)
CPC H10K 59/50 (2023.02) [G02B 5/3041 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An elliptically polarizing plate comprising sequentially, a linear polarizer, a first retardation film, a second retardation film, a third retardation film and a fourth retardation film,
wherein the first retardation film is a +B plate or a −A plate having an Nz value of less than 1 in Equation 1:
Nz=(nx−nz)/(nx−ny).  [Equation 1]
wherein the second retardation film is a −B plate having an Nz value of more than 1 in Equation 1, or a −C plate satisfying Expression 1:
nx=ny>nz  [Expression 1]
wherein the third retardation film has an Nz value of 0.8 to 1.2 in Equation 1, and wherein an in-plane slow axis of the third retardation film forms an angle of 43 degrees to 47 degrees with an absorption axis of the linear polarizer; and
wherein the fourth retardation film is a +B plate having an Nz value of −4.0 or less in Equation 1, or a +C plate satisfying Expression 2:
nx=ny<nz  [Expression 2]
wherein a sum of a thickness direction retardation value of the first retardation film and a thickness direction retardation value of the second retardation film is in a range of −40 nm to 70 nm and the thickness direction retardation (Rth) is defined by Equation 2:
Rth=(nz−ny)×d  [Equation 2]
wherein, nx, ny and nz are refractive indexes of the first to fourth retardation films in x-axis, y-axis and z-axis directions, respectively, and
wherein the x-axis is a direction parallel to an in-plane slow axis of the first to fourth retardation films, the y-axis is a direction parallel to an in-plane fast axis of the first to fourth retardation films, the z-axis is a thickness direction of the first to fourth retardation films, and d is a thickness of the first to fourth retardation films.