Back plate film
The present application relates to a back plate film. The present application provides a back plate film for an under-display camera in which a front camera of a mobile phone can capture a subject without image distortion. The back plate film of the present application can be usefully used in, for example, an OLED panel.
1 . A back plate film comprising: a retardation base material layer; and a first pressure-sensitive adhesive layer formed on one side of the retardation base material layer, wherein an absolute value of an in-plane retardation (R0) value calculated by Equation 1 below of the retardation base material layer is 6,000 nm or more, and an absolute value of a thickness direction retardation (Rth) value calculated by Equation 2 below is 6,000 nm or more:
R
0
=
(
n
x
-
n
y
)
×
d
[
Equation
1
]
Rth
=
[
(
n
x
+
ny
)
/
2
-
nz
]
×
d
[
Equation
2
]
wherein, nx, ny, and nz are refractive indices of the retardation base material layer in the x-axis direction, y-axis direction, and z-axis direction for light with a wavelength of 550 nm, respectively, and d is a thickness (nm) of the retardation base material layer;
wherein the retardation base material layer is configured to compensate phase distortion of light transmitted through the display panel toward an imaging sensor by controlling phase retardation in an optical path;
wherein the absolute value of the in-plane retardation (R0) value of the retardation base material layer is 10,000 nm or less;
wherein the absolute value of the thickness direction retardation (Rth) value of the retardation base material layer is 10,000 nm or less;
wherein the thickness-direction retardation Rth is negative.
2 . The back plate film according to claim 1 , wherein the retardation base material layer has a thickness in a range of 20 μm to 200 μm.
3 . The back plate film according to claim 1 , comprising an antistatic layer formed on a side of the retardation base material layer on which the first pressure-sensitive adhesive layer is not formed, wherein the antistatic layer has a sheet resistance in a range of 104 Q/square to 1011 Q/square.
4 . The back plate film according to claim 1 , wherein the first pressure-sensitive adhesive layer comprises an acrylic resin and a curing agent, and has a thickness in a range of 20 μm to 200 μm.
5 . The back plate film according to claim 1 , wherein the first pressure-sensitive adhesive layer has a pressure-sensitive adhesive force to glass at a peel rate of 0.3 mpm in a range of 1000 gf/in to 4000 gf/in.
6 . The back plate film according to claim 1 , further comprising a protective film present on a side of the retardation base material layer.
7 . The back plate film according to claim 6 , wherein the protective film comprises a first base material film and a second pressure-sensitive adhesive layer formed on one side of the first base material film, the first base material film has a thickness in a range of 20 μm to 200 μm, and the second pressure-sensitive adhesive layer has a thickness in a range of 10 μm to 200 μm.
8 . The back plate film according to claim 7 , wherein the first base material film is a PET (polyethylene terephthalate) film.
9 . The back plate film according to claim 7 , further comprising an antistatic layer formed on one side of at least one of the first base material film and the second pressure-sensitive adhesive layer, wherein the antistatic layer has a sheet resistance of 104 Q/square to 1011 Q/square.
10 . The back plate film according to claim 6 , further comprising a release film present on a side of the first pressure-sensitive adhesive layer.
11 . The back plate film according to claim 10 , wherein the release film comprises a second base material film and a silicone layer formed on one side of the second base material film.
12 . The back plate film according to claim 11 , wherein the second base material film is a PET (polyethylene terephthalate) film.
13 . The back plate film according to claim 11 , comprising an antistatic layer formed on one or both sides of the second base material film, wherein the antistatic layer has a sheet resistance in a range of 104 Q/square to 1011 Q/square.
14 . An organic light emitting display comprising the back plate film of claim 1 and an OLED (organic light emitting diode) panel.
15 . The organic light emitting display according to claim 14 , wherein the first pressure-sensitive adhesive layer of the back plate film is in contact with the OLED panel.
16 . A mobile phone sequentially comprising a cover window, a polarizing plate, a touch sensor, an OLED (organic light emitting diode) panel, the back plate film of claim 1 , and a camera.
17 . The mobile phone according to claim 16 , wherein no front camera region is punched on the OLED panel.