Polarising plate for a planar-switch mode LCD, and a planar-switch mode LCD comprising the same
A polarizer for use in an IPS-LCD includes: a polarizing element; and a retardation film laminate attached to a surface of the polarizing element. The retardation film laminate includes a combination of a +B film and a −B film or a combination of a +B film and a +A film.
1. A polarizer for use in an IPS-LCD, comprising:
a polarizing element; and
a retardation film laminate attached to a surface of the polarizing element,
wherein the retardation film laminate includes a combination of a +B film and a −B film,
wherein optical axes of the +B film and the −B film are parallel to each other,
wherein the +B film is a film meeting nx>ny, nz>ny and nx≠nz, and the −B film is a film meeting nx>ny>nz,
wherein the +B film has a thickness retardation value R th expressed as Equation (2) below of 50 nm to 150 nm at a wavelength of 550 nm, and
wherein the optical axes of the +B film and the −B film are parallel to an absorption axis of the polarizing element, and the +B film and the −B film are directly and sequentially laminated on the polarizing element; or the optical axes of the +B film and the −B film are perpendicular to the absorption axis of the polarizing element, and the −B film and the +B film are directly and sequentially laminated on the polarizing element:
Rth =( nz−ny )× d (2)
wherein nx, ny and nz are, respectively, an x-axis refractive index, a y-axis refractive index and a z-axis refractive index of the +B film or the −B film and d is a thickness of the +B film.
2. The polarizer of claim 1 , wherein the +B film has an in-plane retardation value of 50 nm to 150 nm at a wavelength of 550 nm, and
the −B film has an in-plane retardation value of 30 nm to 70 nm and a thickness retardation value of −30 nm to −120 nm at a wavelength of 550 nm.
3. The polarizer of claim 1 , wherein N z values of the +B film and the −B film are greater than 0 and equal to or less than 4, the N z value being defined as
N z =|1−( R th /R in )|
where R th denotes a thickness retardation value, and R in denotes an in-plane retardation value.
4. The polarizer of claim 1 , where the +B film and the −B film comprise a stretched polymer film or a liquid crystal film.
5. The polarizer of claim 1 , wherein the +B film is a film meeting nz>nx>ny, and the −B film is a film meeting nx>ny>nz.
6. The polarizer of claim 1 , wherein the +B film is a film meeting nx>nz>ny, and the −B film is a film meeting nx>ny>nz.
7. The polarizer of claim 1 , wherein the +B film has an in-plane retardation value of 75 nm to 150 nm at a wavelength of 550 nm and a thickness retardation value of 75 nm to 150 nm at a wavelength of 550 nm, and the −B film has an in-plane retardation value of 40 nm to 70 nm and a thickness retardation value of −65 nm to −40 nm at a wavelength of 550 nm.
8. An IPS-LCD comprising:
a liquid crystal panel comprising a top substrate, a bottom substrate, and a liquid crystal cell disposed between the top substrate and the bottom substrate and filled with liquid crystals having a positive dielectric anisotropy, the liquid crystal panel configured to operate in an IPS mode;
a first polarizer attached to one surface of the liquid crystal panel and in which an absorption axis of a polarizing element is arranged in parallel to an optical axis of the liquid crystal cell; and
a second polarizer attached to the other surface of the liquid crystal cell and having a polarizing element an absorption of which is arranged perpendicular to the optical axis of the liquid crystal cell,
wherein the second polarizer comprises a polarizing element and a retardation film laminate attached to a surface of the polarizing element, and the retardation film laminate includes a combination of a +B film and a −B film,
wherein optical axes of the +B film and the −B film are parallel to each other,
wherein the +B film is a film meeting nx>ny, nz>ny and nx≠nz, and the −B film is a film meeting nx>ny>nz,
wherein nx, ny and nz are, respectively, an x-axis refractive index, a y-axis refractive index and a z-axis refractive index of the +B film or the −B film, and
wherein the optical axes of the +B film and the −B film are parallel to an absorption axis of the polarizing element of the second polarizer, and the +B film and the −B film are directly and sequentially laminated on the polarizing element of the second polarizer; or the optical axes of the +B film and the −B film are perpendicular to the absorption axis of the polarizing element of the second polarizer, and the −B film and the +B film are directly and sequentially laminated on the polarizing element of the second polarizer.
9. The IPS-LCD of claim 8 , wherein the first polarizer comprises:
a polarizing element; and
a protection film attached to one surface or both sides of the polarizing element, the protection film comprising a transparent isotropic film.
10. The IPS-LCD of claim 9 , wherein the second polarizer is attached to a protection film on the other surface of the polarizer to which the laminate of the +B film and the −B film is not attached, the protection film comprising a transparent isotropic film.
11. The IPS-LCD of claim 8 , wherein the +B film has an in-plane retardation value of 50 nm to 150 nm and a thickness retardation value of 50 nm to 150 nm at a wavelength of 550 nm, and the −B film has an in-plane retardation value of 30 nm to 70 nm and a thickness retardation value of −30 nm to −120 nm at a wavelength of 550 nm.
12. The IPS-LCD of claim 8 , wherein the +B film has an in-plane retardation value of 75 nm to 150 nm at a wavelength of 550 nm and a thickness retardation value of 75 nm to 150 nm at a wavelength of 550 nm, and the −B film has an in-plane retardation value of 40 nm to 70 nm and a thickness retardation value of −65 nm to −40 nm at a wavelength of 550 nm.
13. A polarizer for use in an IPS-LCD, comprising:
a polarizing element; and
a retardation film laminate attached to a surface of the polarizing element,
wherein the retardation film laminate includes a combination of a +B film and a +A film,
wherein optical axes of the +B film and the +A film are parallel to each other,
wherein the +B film is a film meeting nx>ny, nz>ny and nx≠nz, and the +A film is a film meeting nx>ny=nz,
wherein the +B film has a thickness retardation value expressed as Equation (2) below of 50 nm to 150 nm at a wavelength of 550 nm, and
wherein the optical axes of the +B film and the +A film are parallel to an absorption axis of the polarizing element, and the +B film and the +A film are directly and sequentially laminated on the polarizing element; or the optical axes of the +B film and the +A film are perpendicular to an absorption axis of the polarizing element, and the +A film and the +B film are directly and sequentially laminated on the polarizing element:
Rth =( nz−ny )× d (2)
wherein nx, ny and nz are, respectively, an x-axis refractive index, a y-axis refractive index and a z-axis refractive index of the +B film or the +A film and d is a thickness of the +B film.
14. The polarizer of claim 13 , wherein the +B film has an in-plane retardation value of 50 nm to 150 nm at a wavelength of 550 nm, and the +A film has an in-plane retardation value of 50 nm to 150 nm at a wavelength of 550 nm.
15. The polarizer of claim 13 , wherein N z values of the +B film and the +A film are greater than 0 and equal to or less than 4, the N z value being defined as
N z =|1−( R th /R in )|
where R th denotes a thickness retardation value, and R in denotes an in-plane retardation value.
16. The polarizer of claim 13 , where the +B film and the +A film comprise a stretched polymer film or a liquid crystal film.
17. The polarizer of claim 13 , wherein the +B film is a film meeting nz>nx>ny, and the −B film is a film meeting nx>ny>nz.
18. The polarizer of claim 13 , wherein the +B film is a film meeting nx>nz>ny, and the −B film is a film meeting nx>ny>nz.
19. The polarizer of claim 13 , wherein the +A film has an in-plane retardation value of 70 nm to 110 nm at a wavelength of 550 nm, and the +B film has an in-plane retardation value of 60 nm to 120 nm at a wavelength of 550 nm and a thickness retardation value of 60 nm to 120 nm at a wavelength of 550 nm.
20. An IPS-LCD comprising:
a liquid crystal panel comprising a top substrate, a bottom substrate, and a liquid crystal cell disposed between the top substrate and the bottom substrate and filled with liquid crystals having a positive dielectric anisotropy, the liquid crystal panel configured to operate in an IPS mode;
a first polarizer attached to one surface of the liquid crystal panel and in which an absorption axis of a polarizing element is arranged in parallel to an optical axis of the liquid crystal cell; and
a second polarizer attached to the other surface of the liquid crystal cell and having a polarizing element an absorption of which is arranged perpendicular to the optical axis of the liquid crystal cell,
wherein the second polarizer comprises a polarizing element and a retardation film laminate attached to a surface of the polarizing element, and the retardation film laminate includes a combination of a +B film and a +A film,
wherein optical axes of the +B film and the +A film are parallel to each other,
wherein the +B film is a film meeting nx>ny, nz>ny and nx≠nz, and the +A film is a film meeting nx>ny=nz,
wherein optical axes of the +B film and the +A film are parallel to each other,
wherein nx, ny and nz are, respectively, an x-axis refractive index, a y-axis refractive index and a z-axis refractive index of the +B film or the +A film, and
wherein the optical axes of the +B film and the +A film are parallel to an absorption axis of the polarizing element of the second polarizer, and the +B film and the +A film are directly and sequentially laminated on the polarizing element of the second polarizer; or the optical axes of the +B film and the +A film are perpendicular to an absorption axis of the polarizing element of the second polarizer, and the +A film and the +B film are directly and sequentially laminated on the polarizing element of the second polarizer.
21. The IPS-LCD of claim 20 , wherein the first polarizer comprises:
a polarizing element; and
a protection film attached to one surface or both sides of the polarizing element, the protection film comprising a transparent isotropic film.
22. The IPS-LCD of claim 21 , wherein the second polarizer is attached to a protection film on the other surface of the polarizer to which the laminate of the +B film and the +A film is not attached, the protection film comprising a transparent isotropic film.
23. The IPS-LCD of claim 20 , wherein the +A film has an in-plane retardation value of 50 nm to 150 nm at a wavelength of 550 nm, and the +B film has an in-plane retardation value of 50 nm to 150 nm and a thickness retardation value of 50 nm to 150 nm at a wavelength of 550 nm.
24. The IPS-LCD of claim 20 , wherein the +A film has an in-plane retardation value of 70 nm to 110 nm at a wavelength of 550 nm, and the +B film has an in-plane retardation value of 60 nm to 120 nm at a wavelength of 550 nm and a thickness retardation value of 60 nm to 120 nm at a wavelength of 550 nm.