Polarizing plate having local depolarization area and method for manufacturing same
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.
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/cm 2 -5W/cm 2 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/cm 2 -5W/cm 2 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.