US 12,271,014 B2
Foldable display
Shotaro Nishio, Tsuruga (JP); Kiwamu Kawai, Tsuruga (JP); and Akira Shimizu, Tsuruga (JP)
Assigned to TOYOBO CO., LTD., Osaka (JP)
Appl. No. 17/615,433
Filed by TOYOBO CO., LTD., Osaka (JP)
PCT Filed May 15, 2020, PCT No. PCT/JP2020/019485
§ 371(c)(1), (2) Date Nov. 30, 2021,
PCT Pub. No. WO2020/241313, PCT Pub. Date Dec. 3, 2020.
Claims priority of application No. 2019-101025 (JP), filed on May 30, 2019.
Prior Publication US 2022/0236468 A1, Jul. 28, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. G02B 5/30 (2006.01); G09F 9/30 (2006.01)
CPC G02B 5/3016 (2013.01) [G02B 5/305 (2013.01); G02B 5/3083 (2013.01); G09F 9/301 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A foldable display comprising at least:
a surface protective film;
a polarizer; and
a retardation layer,
wherein the surface protective film is a polyester film satisfying the following conditions and having a thickness of from 10 μm to 80 μm:
(1) a refractive index in a bending direction is from 1.590 to 1.602;
(2) a refractive index in a folding portion direction is from 1.670 to 1.700;
(3) a refractive index in a thickness direction is 1.520 or less; and
(4) a density is 1.380 g/cm3 or more,
wherein the polyester film is a biaxially stretched polyethylene terephthalate film, and
wherein the bending direction refers to a direction orthogonal to a folding portion of the polyester film at a time when the polyester film is folded.