Polarizing plate for in-plane switching mode and optical display apparatus comprising the same

1. A polarizing plate, comprising:

a polarizer;

a first protective layer on an upper surface of the polarizer; and

a second protective layer on a lower surface of the polarizer,

wherein, an axis of the polarizer having a high index of refraction in an in-plane direction of the polarizer is a reference axis (0°), an angle of an axis of the first protective layer having a low index of refraction in an in-plane direction of the first protective layer is in a range of about −5° to +5°, the first protective layer has an in-plane retardation of about 5,000 nm or more at a wavelength of 550 nm, the second protective layer comprises a positive C plate layer, and the second protective layer satisfies at least one of the following Relations 1 and 2:

Re(450)/Re(550)>Re(650)/Re(550),  Relation 1

where Re(450), Re(550), and Re(650) are in-plane retardations (unit: nm) of the second protective layer at wavelengths of about 450 nm, about 550 nm, and about 650 nm, respectively, and

|Rth(450)|/|Rth(550)|>|Rth(650)|/|Rth(550)|,  Relation 2

where |Rth(450)|, |Rth(550)|, and |Rth(650)| are absolute values of out-of-plane retardations (unit: nm) of the second protective layer at wavelengths of about 450 nm, about 550 nm, and about 650 nm, respectively.

2. The polarizing plate according to claim 1 , wherein the second protective layer satisfies both Relation 1 and Relation 2.

3. The polarizing plate according to claim 1 , wherein, in Relation 1, Re(450)/Re(550) is in a range of about 0.1 to about 10, and Re(650)/Re(550) is in a range of about 0.1 to about 8.

4. The polarizing plate according to claim 1 , wherein, in Relation 2, |Rth(450)|/|Rth(550)| is in a range of about 0.1 to about 10, and |Rth(650)|/|Rth(550)| is in a range of about 0.1 to about 8.

5. The polarizing plate according to claim 1 , wherein the second protective layer has an out-of-plane retardation of about −150 nm to about −10 nm at a wavelength of 550 nm.

6. The polarizing plate according to claim 1 , wherein the second protective layer is a non-liquid crystal layer.

7. The polarizing plate according to claim 6 , wherein the second protective layer is a coating layer formed of a composition comprising at least one selected from among a cellulose ester compound or a polymer thereof and an aromatic compound or a polymer thereof.

8. The polarizing plate according to claim 1 , wherein the axis of the first protective layer having the low index of refraction in the in-plane direction thereof is a machine direction (MD) of the first protective layer, and an axis of the first protective layer having a high index of refraction in the in-plane direction thereof is a transverse direction (TD) of the first protective layer.

9. The polarizing plate according to claim 1 , wherein the axis of the polarizer having the high index of refraction in the in-plane direction thereof is a machine direction of the polarizer, and an axis of the polarizer having a low index of refraction in the in-plane direction thereof is a transverse direction of the polarizer.

10. The polarizing plate according to claim 1 , wherein the second protective layer is directly formed on the polarizer.

11. The polarizing plate according to claim 1 , further comprising a third protective layer.

12. The polarizing plate according to claim 11 , wherein the third protective layer has an in-plane retardation of about 100 nm or less at a wavelength of 550 nm.

13. The polarizing plate according to claim 11 , wherein the third protective layer has an out-of-plane retardation of about −10 nm to about 200 nm at a wavelength of 550 nm.

14. The polarizing plate according to claim 11 , wherein the third protective layer has a degree of biaxiality of −1 to 10 at a wavelength of 550 nm.

15. The polarizing plate according to claim 11 , wherein a laminate of the third protective layer and the second protective layer satisfies at least one of the following Relations 3 and 4:

Re(450)/Re(550)>Re(650)/Re(550),  Relation 3

where Re(450), Re(550), and Re(650) are in-plane retardations (unit: nm) of the laminate of the third protective layer and the second protective layer at wavelengths of about 450 nm, about 550 nm, and about 650 nm, respectively, and Relation 4

|Rth(450)|/|Rth(550)|>|Rth(650)|/|Rth(550)|,  Relation 4

where |Rth(450)|, |Rth(550)|, and |Rth(650)| are absolute values of out-of-plane retardations (unit: nm) of the laminate of the third protective layer and the second protective layer at wavelengths of about 450 nm, about 550 nm, and about 650 nm, respectively.

16. The polarizing plate according to claim 15 , wherein, in Relation 3, Re(450)/Re(550) is in a range of about 0.1 to about 10, and Re(650)/Re(550) is in a range of about 0.1 to about 8.

17. The polarizing plate according to claim 15 , wherein, in Relation 4, |Rth(450)|/|Rth(550)| is in a range of about 0.1 to about 10, and |Rth(650)|/|Rth(550)| is in a range of about 0.1 to about 8.

18. The polarizing plate according to claim 11 , wherein a laminate of the third protective layer and the second protective layer has an out-of-plane retardation of about −150 nm to about −10 nm at a wavelength of 550 nm.

19. The polarizing plate according to claim 1 , wherein the polarizing plate has an in-plane retardation of about −10 nm to about 10 nm at a wavelength of 550 nm.

20. An optical display apparatus comprising the polarizing plate according to claim 1 .