Optical film, liquid crystal display device comprising same, and method for manufacturing protective film used therefor

• US 9,880,334 B2
• Filed: 12/15/2014
• Issued: 01/30/2018
• Est. Priority Date: 06/02/2014
• Status: Active Grant

• Current Assignee: Samsung SDI Company Limited
• Original Assignee: Samsung SDI Company Limited
• Inventors: Yu, So Hee, Kim, Ran, Lee, Seung Kyu
• Primary Examiner(s): Williams, Joseph L
• Assistant Examiner(s): DIAZ, JOSE
• Application Number:
  US15/316,115
• Publication Number:
  US 20170108632A1
• Time in Patent Office: 1,142 Days
• CPC Class Codes: B32B 27/00 Layered products comprising a layer of synthetic resin fibrous or filamentary layer made of a synthetic resin B32B5/02; particulate layer made of a synthetic resin B32B5/16; foamed layer made of a synthetic resin B32B5/18
• CPC Class Codes: C08J 2367/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds; C08J2367/06 takes precedence
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/133507 Films for enhancing the luminance
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133562 on the viewer side
• CPC Class Codes: G02F 1/133567 on the back side
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 2201/50 Protective arrangements

Abstract

An optical film, a liquid crystal display including the same, and a method for manufacturing a protective film used therefor are provided. An optical film includes a polarizer and a protective film laminated or stacked on at least one surface of the polarizer, and a thickness-direction retardation (Re) of the protective film is in the range of 0 nm to 200 nm, and an out-of-plane retardation (Rth) of the protective film is in the range of 300 nm to 1,200 nm.

Claims

1. An optical film comprising:

a polarizer; and

a protective film on at least one surface of the polarizer,

wherein the protective film has an in-plane retardation (Re) of 0 nm to 200 nm and an out-of-plane retardation (Rth) of 300 nm to 1,200 nm.

2. The optical film according to claim 1, wherein the protective film has a thickness of 1 μ

m to 55 μ

m.

3. The optical film according to claim 1, wherein the protective film comprises a polyester material.

4. The optical film according to claim 3, wherein the protective film comprises polyethylene terephthalate, polyethylene naphthalate, or a copolymer comprising polyethylene terephthalate and polyethylene naphthalate.

5. The optical film according to claim 4, wherein the protective film has a triple co-extrusion structure comprising polyethylene terephthalate, polyethylene naphthalate, or a copolymer comprising polyethylene terephthalate and polyethylene naphthalate.

6. The optical film according to claim 1, further comprising:

a retardation compensation film on an opposite surface of the polarizer with respect to the at least one surface of the polarizer, on which the protective film is located.

7. A liquid crystal display comprising:

a liquid crystal cell;

a backlight unit;

a lower polarizing plate between the liquid crystal cell and the backlight unit; and

an upper polarizing plate on a visible side of the liquid crystal cell, the upper polarizing plate comprising the optical film according to claim 1.

8. The liquid crystal display according to claim 7, wherein the protective film of the optical film is disposed on a visible side of the upper polarizing plate.

9. The liquid crystal display according to claim 8, further comprising:

a brightness enhancement film between the lower polarizing plate and the backlight unit.

10. The liquid crystal display according to claim 7, wherein the lower polarizing plate comprises an optical film comprising:

a polarizer; and

a protective film on at least one surface of the polarizer of the optical film of the lower polarizing plate,

wherein the protective film of the optical film of the lower polarizing plate has an in-plane retardation (Re) of 0 nm to 200 nm and an out-of-plane retardation (Rth) of 300 nm to 1,200 nm.

11. The liquid crystal display according to claim 10, wherein the protective film of the optical film of the lower polarizing plate is on a light source side of the lower polarizing plate.

12. The liquid crystal display according to claim 11, wherein the protective film of the optical film of the upper polarizing plate is on a visible side of the upper polarizing plate.

13. The liquid crystal display according to claim 12, further comprising:

a brightness enhancement film between the lower polarizing plate and the backlight unit.

14. A method of manufacturing a protective film, the method comprising:

manufacturing a non-stretched polyester film; and

stretching the non-stretched polyester film,

wherein a stretching ratio (MD;

TD) is from 2.0;

1.0 to 3.0 to 3.0;

2.0 to 4.0.