Liquid crystal display device, polarizer and protective film

• US 10,503,016 B2
• Filed: 01/03/2018
• Issued: 12/10/2019
• Est. Priority Date: 06/22/2010
• Status: Active Grant

• Current Assignee: Toyobo Company Limited
• Original Assignee: Toyobo Company Limited
• Inventors: Murata, Koichi, Sasaki, Yasushi
• Primary Examiner(s): Pan, Jia X
• Application Number:
  US15/861,186
• Publication Number:
  US 20180173038A1
• Time in Patent Office: 706 Days
• Field of Search: 349117, 349181
• 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 1/133528 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 1/1336 Illuminating devices
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 1/133624 characterised by their spectral emissions
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 2201/50 Protective arrangements
• CPC Class Codes: G02F 2202/40 Materials having a particular birefringence, retardation

Abstract

Provided is a liquid crystal display device that has excellent visibility while using a protective film comprising a polyester film. The liquid crystal display device comprises a backlight light source, and a liquid crystal cell disposed between two polarizers; the backlight light source being a white light-emitting diode; each of the polarizers comprising a polarizing film and protective films laminated on both sides of the polarizing film; and at least one of the protective films being a polyester film having a retardation of 3,000 to 30,000 nm.

Claims

1. A display device comprising a first polarizer, a liquid crystal cell, a second polarizer, and a backlight source, wherein

the liquid crystal cell has a light-outgoing side and a light-incoming side,

the first polarizer is disposed on the light-outgoing side of the liquid crystal cell,

the first polarizer comprises (a) a first polarizing film and (b) a first protective film laminated on the light-outgoing side of the first polarizing film,

the second polarizer is disposed on the light-incoming side of the liquid crystal cell,

the second polarizer comprises (a) a second polarizing film and (b) a second protective film laminated on the light-incoming side of the second polarizing film,

the first protective film optionally is an oriented film having an in-plane retardation of 3,215 nm or more and less than 10,000 nm and a ratio of in-plane retardation to thickness-direction retardation (Re/Rth) of 0.5 to 2.0,

the second protective film is an oriented film having an in-plane retardation of 3,215 nm or more and less than 10,000 nm and a ratio of in-plane retardation to thickness-direction retardation (Re/Rth) of 0.5 to 2.0, and

no oriented film having an in-plane retardation of 3,215 to 30,000 nm is disposed between the light-incoming side of the first polarizing film and the light-outgoing side of the second polarizing film.

2. The display device of claim 1, wherein the first protective film is an oriented film having an in-plane retardation of 3,215 nm or more and less than 10,000 nm and a ratio of in-plane retardation to thickness-direction retardation (Re/Rth) of 0.5 to 2.0.

3. The display device of claim 2, wherein the first protective film that is an oriented film having an in-plane retardation of 3,215 nm or more and less than 10,000 nm and a ratio of in-plane retardation to thickness-direction retardation (Re/Rth) of 0.5 to 2.0 is a polyester film.

4. The display device of claim 1, wherein the second protective film that is an oriented film having an in-plane retardation of 3,215 nm or more and less than 10,000 nm and a ratio of in-plane retardation to thickness-direction retardation (Re/Rth) of 0.5 to 2.0 is a polyester film.

5. The display device of claim 1, wherein the first protective film is not an oriented film having an in-plane retardation of 3,215 nm or more and less than 10,000 nm and a ratio of in-plane retardation to thickness-direction retardation (Re/Rth) of 0.5 to 2.0 and is a triacetyl cellulose film, an acrylic film, or a norbornene film.

6. The display device of claim 1, wherein the first protective film is not an oriented film having an in-plane retardation of 3,215 nm or more and less than 10,000 nm and a ratio of in-plane retardation to thickness-direction retardation (Re/Rth) of 0.5 to 2.0 and is a birefringence-free film.