Optical filter for anti-reflection and organic light-emitting device
The present application relates to an optical filter and an organic light-emitting display device. The optical filter of the present application has excellent omnidirectional antireflection performance and color characteristics on the side as well as the front. The optical filter can be applied to an organic light-emitting device to improve visibility.
1. An optical filter for anti-reflection sequentially comprising a first retardation film having an in-plane optical axis and having quarter-wave phase retardation characteristics, a second retardation film having a plurality of optical axes, and a polarizer having an absorption axis formed in one direction,
wherein the optical axis of the first retardation film forms an angle of 40 degrees to 50 degrees with the absorption axis of the polarizer,
wherein the second retardation film comprises a liquid crystal layer comprising liquid crystal molecules in a splay alignment state in which tilt angles of the liquid crystal molecules present in the liquid crystal layer gradually change along the thickness direction of the liquid crystal layer, and a projection of all the optical axes defined by the splay alignment of the second retardation film onto a plane of the second retardation film is parallel or orthogonal to the absorption axis of the polarizer,
wherein the liquid crystal molecules include rod-shaped or disc-shaped liquid crystal molecules, and
wherein the optical axes of the second retardation film are gradually changed along the thickness direction of the film so as to have tilt angles of 70 degrees to 90 degrees at both surfaces of the film, respectively and a tilt angle of 0 degrees to 70 degrees at the middle part in the thickness direction of the film.
2. The optical filter according to claim 1 , wherein the first retardation film satisfies Equation 2 below:
R (450)/ R (550)< R (650)/ R (550) [Equation 2]
wherein, R (λ) is an in-plane retardation of the retardation film for light of λ nm.
3. The optical filter according to claim 1 , wherein the second retardation film has a thickness of 0.3 μm will to 5 μm.
4. The optical filter according to claim 1 , wherein the liquid crystal molecules have refractive index anisotropy of 0.03 to 0.2.
5. The optical filter according to claim 1 , wherein the liquid crystal layer comprises disc-shaped liquid crystal molecules and the optical axes of the second retardation film are gradually changed along the thickness direction of the film so as to have tilt angles of 70 degrees to 90 degrees at both surfaces of the film, respectively and a tilt angle of 0 degrees to 30 degrees at the middle part in the thickness direction of the film.
6. The optical filter according to claim 1 , wherein the liquid crystal layer comprises the rod-shaped liquid crystal molecules and the optical axes of the second retardation film are gradually changed along the thickness direction of the film so as to have tilt angles of 70 degrees to 90 degrees at both surfaces of the film, respectively, and a tilt angle of 0 degrees to 30 degrees at the middle part in the thickness direction of the film.
7. The optical filter according to claim 1 , wherein the liquid crystal layer comprises disc-shaped liquid crystal molecules, the projection of all the optical axes of the second retardation film onto the plane of the second retardation film is orthogonal to the absorption axis of the polarizer, the optical axes of the second retardation film have tilt angles of 75 degrees to 90 degrees at both surfaces, respectively and a tilt angle of 5 degrees to 40 degrees at the middle part of the thickness direction of the film, and the second retardation film has a thickness of 2 μm to 3 μm.
8. The optical filter according to claim 1 , wherein the liquid crystal layer comprises the rod-shaped liquid crystal molecules, the projection of all the optical axes of the second retardation film onto the plane of the second retardation film is parallel to the absorption axis of the polarizer, the optical axes of the second retardation film have tilt angles of 70 degrees to 90 degrees at both surfaces, respectively and a tilt angle of 0 degrees to 30 degrees at the middle part of the thickness direction of the film, and the second retardation film has a thickness of 0.5 μm to 1.5 μm.
9. An organic light-emitting device comprising the optical filter of claim 1 and an organic light-emitting display panel.
10. The organic light-emitting device according to claim 9 , wherein the first retardation film of the optical filter is disposed adjacent to the organic light-emitting display panel as compared with the polarizer.
11. The organic light-emitting device according to claim 1 , wherein the liquid crystal molecules have refractive index anisotropy of 0.06-0.12.
12. The optical filter according to claim 1 , wherein the splay alignment state is a linear splay alignment state.
13. The organic light-emitting device according to claim 10 , wherein the organic light-emitting display panel may comprise a base substrate, a lower electrode, an organic light-emitting layer, an upper electrode and a sealing substrate.