Polarizing plate having local depolarization area and method for manufacturing same

• US 10,081,141 B2
• Filed: 09/26/2014
• Issued: 09/25/2018
• Est. Priority Date: 09/30/2013
• Status: Active Grant

• Current Assignee: LG Chem Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: Lee, Byung Sun, Nam, Sung Hyun, Rah, Kyun Il
• Primary Examiner(s): Lei, Jie
• Application Number:
  US14/911,216
• Publication Number:
  US 20160195767A1
• Time in Patent Office: 1,460 Days
• Field of Search: 35948601, 35948702, 35948901, 35948906, 35949401, 359352, 349 96
• CPC Class Codes: B29C 2035/0827 using UV radiation
• CPC Class Codes: B29C 2035/0838 using laser
• CPC Class Codes: B29C 71/04 by wave energy or particle radiation , e.g. for curing or vulcanising preformed articles during moulding, e.g. in a mould B29C35/08
• CPC Class Codes: B29K 2029/04 PVOH, i.e. polyvinyl alcohol B29K2031/04 takes precedence
• CPC Class Codes: B29L 2011/00 Optical elements, e.g. lenses, prisms
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid

Abstract

The present invention relates to a polarizing plate that comprises a polyvinyl alcohol-based polarizer dyed with any one or more of iodine and a dichroic dye and that locally has a depolarized region having a single transmittance of 70% or more at a wavelength ranging from 400 nm to 800 nm, the depolarized region being formed by irradiating light having a specific wavelength selected from a wavelength range of 200 nm to 800 nm, and to a manufacturing method thereof.

Claims

1. A method for manufacturing a polarizing plate, the method comprising a step of irradiating a portion of a polarizing element, which comprises a polyvinyl alcohol-based polarizer dyed with any one or more of iodine and a dichroic dye, with light having a wavelength from 532 nm to 800 nm, to depolarize the portion to form a depolarized region,

wherein the depolarized region of the polarizing plate has a degree of polarization of 20% or less,

wherein a region of the polarizing plate, which excludes the depolarized region, has a single transmittance of 40%-45%, and a degree of polarization of 99% or more,

wherein the step of irradiating a portion of the polarizing element with light to depolarize the portion is performed using a light-emitting diode (LED) lamp or a laser lamp at an intensity of 1W/cm²-5W/cm² for 1-1,000 second, and

wherein the light having a wavelength from 532 nm to 800 nm is a polarized light and irradiated such that an angle between a polarization direction of the polarized light and a light absorption axis of the polarizing plate is 5°

or less.

2. The method of claim 1, wherein the depolarized region of the polarizing plate has a single transmittance of 70% or more at a wavelength ranging from 400 nm to 800 nm.

3. The method of claim 1, wherein an area of the depolarized region accounts for 0.005%-40% of a total area of the polarizing plate.

4. A method for manufacturing an image display device comprising a display panel and a polarizing plate attached to one or both surfaces of the display panel,

the method comprising a step of irradiating a portion of a polarizing element, which comprises a polyvinyl alcohol-based polarizer dyed with any one or more of iodine and a dichroic dye, with light having a wavelength from 532 nm to 800 nm, to depolarize the portion to form a depolarized region,

wherein the depolarized region of the polarizing plate has a degree of polarization of 20% or less,

wherein a region of the polarizing plate, which excludes the depolarized region, has a single transmittance of 40%-45%, and a degree of polarization of 99% or more,

wherein the step of irradiating a portion of the polarizing element with light to depolarize the portion is performed using a light-emitting diode (LED) lamp or a laser lamp at an intensity of 1W/cm²-5W/cm² for 1-1,000 seconds, and

wherein the light having a wavelength from 532 nm to 800 nm is a polarized light irradiated at an angle of 5°

or less with respect to light absorption axis of the polarizing plate.

5. The image display device of claim 4, wherein a camera module is located in the depolarized region.