Optical film material roll and method for manufacturing image display device using thereof

• US 8,821,674 B2
• Filed: 04/16/2012
• Issued: 09/02/2014
• Est. Priority Date: 04/10/2009
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Nakazono, Takuya, Umemoto, Seiji, Takita, Tomohito, Shimanoe, Fumihito, Yano, Yuuki, Oosawa, Teruaki
• Primary Examiner(s): GRAY, LINDA LAMEY
• Application Number:
  US13/447,963
• Publication Number:
  US 20120199265A1
• Time in Patent Office: 869 Days
• Field of Search: 156/256, 156/257, 156/264, 156/268, 156/270, 156/354, 156/353
• US Class Current: 156/256
• CPC Class Codes: B32B 2041/04 Detecting wrong registration, misalignment, deviation, failure
• CPC Class Codes: B32B 2457/202 LCD, i.e. liquid crystal displays
• CPC Class Codes: B32B 41/00 Arrangements for controlling or monitoring lamination processes; Safety arrangements
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/03 Viewing layer characterised by chemical composition
• CPC Class Codes: C09K 2323/031 Polarizer or dye
• CPC Class Codes: C09K 2323/035 Ester polymer, e.g. polycarbonate, polyacrylate or polyester
• CPC Class Codes: G01N 2021/888 Marking defects
• CPC Class Codes: G02B 5/3041 comprising multiple thin layers, e.g. multilayer stacks
• CPC Class Codes: Y10T 156/1062 Prior to assembly
• CPC Class Codes: Y10T 156/1074 Separate cutting of separate sheets or webs
• CPC Class Codes: Y10T 156/1075 of plural laminae from single stock and assembling to each other or to additional lamina
• CPC Class Codes: Y10T 156/1085 One web only

Abstract

Disclosed is a material roll that includes a roll of an optical film having defect information markings printed thereon and is resistant to the formation of a defect by the transfer of a bump/dent deformation at the marking site. The material roll includes a long sheet of an optical film with polarizer wound into roll shape; and marking(s) formed at or in a vicinity of at least one defect site. The marking has an optical density of 1.5 or more, and a thickness of a center part of the marking is 1.5 μm or less. The marking preferably has an optical density per unit thickness of 2.5 μm⁻¹ or more.

Claims

1. A method for manufacturing an image display device through continuously bonding, to an optical display unit, a piece of an optical film comprising a polarizer, comprising

performing a series of continuous steps that comprise:

a step of providing a material roll comprising a long sheet of an optical film wound into roll shape, wherein at least one marking is formed at or in a vicinity of at least one defect site of the optical film;

a step of feeding the long sheet of the optical film from the material roll;

a marking detection step of detecting the presence or absence of the marking by inspection means capable of identifying it;

a cutting step of cutting all or part of optical layers of the optical film to form a rectangular optical film piece; and

a bonding step of bonding the optical film piece to a substrate of an optical display unit, wherein

the material roll has a width corresponding to the length of a long or short side of the optical display unit so that the optical film has a width that is entirely available for forming a product part to be bonded to the optical display unit,

in the cutting step, the long sheet of the optical film is transversely cut at predetermined intervals along the longitudinal direction of the optical film to form a rectangular optical film piece of a predetermined size corresponding to a size of the optical display unit,

the marking has an optical density of 1.5 or more, and

a thickness of a center part of the marking is 1.5 μ

m or less.

2. The method according to claim 1, wherein the marking has an optical density per unit thickness of 2.5 μ

m<sup>−

1</sup> or more.

3. The method according to claim 1, wherein the marking has an absorption peak at a wavelength of 500 nm to 600 nm.

4. The method according to claim 2, wherein the marking has an absorption peak at a wavelength of 500 nm to 600 nm.

5. The method according to claim 1, wherein the cutting step is performed in such a manner as to remove, from the product part to be bonded to the optical display unit, a marking-containing part detected in the marking detection step.

6. The method according to claim 2, wherein the cutting step is performed in such a manner as to remove, from the product part to be bonded to the optical display unit, a marking-containing part detected in the marking detection step.

7. The method according to claim 3, wherein the cutting step is performed in such a manner as to remove, from the product part to be bonded to the optical display unit, a marking-containing part detected in the marking detection step.

8. The method according to claim 1, wherein an optical film piece having a marking-containing part detected in the marking detection step is bonded to a part other than the substrate of the optical display unit.

9. The method according to claim 2, wherein an optical film piece having a marking-containing part detected in the marking detection step is bonded to a part other than the substrate of the optical display unit.

10. The method according to claim 3, wherein an optical film piece having a marking-containing part detected in the marking detection step is bonded to a part other than the substrate of the optical display unit.

11. The method according to claim 4, wherein an optical film piece having a marking-containing part detected in the marking detection step is bonded to a part other than the substrate of the optical display unit.