Polarizing plate and optical display device including the same

Abstract

The present invention provides a polarizing plate, comprising: a polarizer and a protective layer formed on at least one surface of the polarizer; and an optical display device including the polarizer. The polarizing plate includes a first region and a second region in an image display area, wherein the first region and the second region have different transmittances at the same wavelength, the first region has a transmittance of about 50% to 80%, and the first region has a color value a* of about -13 to 2 and a color value b* of about 1 to 35.

Description

Technical Field

[0001] The present invention relates to a polarizing plate and an optical display device including the polarizing plate. Background Art

[0002] The polarizing plate is provided to the optical display device to display an image or improve the image quality. In a mobile display such as a mobile phone, the polarizing plate may be used as an intermediate path of an image sensor such as a camera to take a picture or an image.

[0003] Reference Figure 2 (A), the optical display device includes: a display panel 50, which includes a base layer 51 and a plurality of light emitting diodes 52; a polarizing plate 40, which is formed on the display panel 50; a cover glass 60, which is formed on the polarizing plate 40; and an image sensor 10, which is arranged to pass through a portion of the display panel 50. The image sensor 10 is disposed inside the polarizing plate 40 to pass through a portion of the polarizing plate 40. The area 40a of the polarizing plate 40 corresponding to the image sensor is a non-image display area. In order to ensure a space for receiving the image sensor 10 therein, the polarizing plate 40 is processed by a physical stamping method. However, in this case, due to cracks in the area around the stamping area of ​​the area 40a of the polarizing plate 40, the image display area 40b provides a poor image.

[0004] refer to Figure 2 (B), the optical display device may include a polarizing plate 70, which is formed with a region 70a for operating the image sensor 10 and an image display region 70b, and the region 70a is formed by a chemical or optical method rather than physical stamping of the polarizing plate 40, such as Figure 2 (A) In this case, the region 70a corresponds to a non-image display region. In addition, the display panel 50 including the light emitting diode is separated from the image sensor 10, making it difficult to perform mechanical processing or the like.

[0005] In recent years, the art has developed an optical display device including an image sensor disposed at a lower portion thereof, rather than defining an area of ​​the image sensor penetrating a portion of a display panel including a light emitting diode to ensure a space for the image sensor, such as Figure 2 (A) and Figure 2 (B) is shown. In this case, the area of ​​the polarizing plate corresponding to the image sensor also needs to perform the image display function and prevent the image sensor from being visually observed from the outside during the image display function, while providing a clear image during shooting. However, there are limitations to using a typical polarizing plate in the above optical display device.

[0006] The background art of the present invention is disclosed in Japanese Unexamined Patent Publication No. 2014-081482 and the like. Summary of the invention

[0007]

Technical issues

[0008] One aspect of the present invention provides a polarizing plate, which is applied to an optical display device, such as a camera, having an image sensor disposed in its image display area, and can perform an image display function by suppressing external visual observation of the image sensor when the image sensor is not used, while improving the image capture resolution when the image sensor is used.

[0009] Another aspect of the present invention is to provide an optical display device including the polarizing plate according to the present invention.

[0010]

Technical solution

[0011] One aspect of the present invention relates to a polarizing plate.

[0012] 1. The polarizing plate comprises: a polarizer; and a protective layer formed on at least one surface of the polarizer, and the polarizing plate has a first area and a second area within an image display area, wherein the first area and the second area have different transmittances at the same wavelength; and wherein the first area has a transmittance of 50% to 80%, a color value a* of about -13 to about 2, and a color value b* of about 1 to about 35.

[0013] 2. In Figure 1 In the embodiment, the first region may have a polarization degree of about 25% to about 80%.

[0014] 3. In 1 and 2, the first region may have an iodine content of about 0.01 wt % to about 5 wt %.

[0015] 4. In 1 to 3, the first area may have an image display function and an image capturing function.

[0016] 5. In 1 to 4, the second region may have a light transmittance of about 40% to less than about 50%.

[0017] Another aspect of the present invention relates to an optical display device including the polarizing plate according to the present invention.

[0018]

Beneficial Effects

[0019] The present invention provides a polarizing plate which is applied to an optical display device having an image sensor, such as an image sensor, arranged in its image display area, and can perform an image display function by externally suppressing visual observation of the image sensor when the image sensor is not used, while improving the shooting resolution of the image when the image sensor is used.

[0020] The present invention provides an optical display device including the polarizing plate according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a cross-sectional view of an optical display device including a polarizing plate according to the present invention.

[0022] Figure 2 is a cross-sectional view of an optical display device including a typical image sensor.

[0023] Figure 3 The color coordinate evaluation results of the first region of the polarizing plates of Example 1 and Comparative Examples 1 and 2 are shown. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. It should be understood that the present invention can be embodied in different ways and is not limited to the following embodiments. In the accompanying drawings, in order to clearly describe the present invention, components that are not related to the description are omitted, and the same components will be represented by the same reference numerals throughout the specification. Although the length, thickness or width of various components can be magnified in the drawings for understanding, the present invention is not limited thereto.

[0025] In this document, spatial relative terms such as "upper" and "lower" are defined with reference to the accompanying drawings. Therefore, it should be understood that the term "upper surface" can be used interchangeably with the term "lower surface".

[0026] Herein, the "transmittance" and "polarization degree" of the polarizing plate are values ​​measured at a wavelength of about 380 nm to about 780 nm, preferably at a wavelength of about 550 nm. "Transmittance" refers to the total transmittance, not the orthogonal transmittance.

[0027] Herein, regarding the “transmittance of the first region”, even at the same wavelength, the first region has the same transmittance throughout its entire region. However, when the transmittance of the first region is not the same throughout its entire region at the same wavelength, the transmittance of the first region refers to its average transmittance.

[0028] Herein, regarding the “transmittance of the second region”, even at the same wavelength, the second region has the same transmittance throughout its entire region. However, when the transmittance is not the same throughout the second region at the same wavelength, the transmittance of the second region refers to its average transmittance.

[0029] Herein, "average transmittance" refers to the average value of transmittance within the wavelength range in the region where the average transmittance is to be measured. For example, the average transmittance can be obtained from the average value of transmittance at any specified plurality of points in the region where the average transmittance is to be measured.

[0030] As used herein to express a specific numerical range, "X to Y" means "greater than or equal to X and less than or equal to Y (X≤ and ≤Y)."

[0031] A polarizing plate according to an embodiment of the present invention includes a polarizer and a protective layer formed on at least one surface of the polarizer. In some embodiments, the polarizing plate includes a polarizer and protective films respectively formed on opposite surfaces of the polarizer. In other embodiments, the polarizing plate may include a polarizer and a protective film formed only on one surface of the polarizer.

[0032] The polarizing plate includes a first area and a second area in an image display area. The "image display area" refers to an area where an image is displayed on an optical display device having a polarizer. In the polarizing plate, the image display area may occupy an area ratio of about 90% to about 100%, preferably about 100%. In one embodiment, the polarizing plate may not include a non-image display area.

[0033] The first area and the second area have different light transmittances at the same wavelength. Thus, when the first area and the second area can perform image display functions, the first area can further perform an external image capturing function through an image sensor such as a camera, unlike the second area.

[0034] The first area has a transmittance of about 50% to about 80%. Within this range, when the image sensor is not used, the first area can realize the image display function by suppressing the visual observation of the image sensor externally, while improving the image shooting resolution when the image sensor is used. Specifically, using the above-mentioned transmittance, the first area according to the present invention can realize all the above-mentioned effects in the laminate of the image sensor-display panel containing light-emitting diodes-polarizer in the optical display device. The display panel containing light-emitting diodes and the image sensor are sequentially arranged under the first area, so that the first area can perform the image display function and the external image shooting function at the same time. The optical display device according to an embodiment of the present invention will be described in detail below.

[0035] The second region performs only an image display function, which is independent of the image display function implemented by the image sensor in the optical display device. Therefore, the second region has a lower light transmittance than the first region.

[0036] In one embodiment, the transmittance difference between the first area and the second area may be in the range of about 5% to about 30%, preferably about 10% to 30%. Within this range, the optical display device including the polarizing plate can achieve a uniform image across the entire screen by reducing the image difference between the first area where the camera is disposed and the second area where the camera is not disposed while preventing the camera from observing externally.

[0037] The second region may have a light transmittance of about 40% to less than about 50% (e.g., 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, or 49%), specifically, about 40% to about 45%. Within this range, the second region can effectively implement an image display function.

[0038] Although the first region and the second region may have the same polarization degree, it is desirable that the first region has a lower polarization degree than the second region in consideration of a process of forming the first region described below.

[0039] In one embodiment, the first region may have a polarization degree of about 25% to about 80% (e.g., 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%), specifically, about 28% to about 70%. Within this range, the first region does not hinder the camera's recognition of the object. In one embodiment, the second region may have a polarization degree of about 90% or greater, specifically, about 90% to 100%. Within this range, the second region can provide an anti-reflection effect relative to external light.

[0040] Next, we will refer to Figure 1 A polarizing plate according to an embodiment of the present invention is described. Figure 1 is a cross-sectional view of an optical display device including the polarizing plate according to the present invention.

[0041] Reference Figure 1 The polarizing plate 100 includes a first region 110 and a second region 120 .

[0042] The entirety of the first region 110 and the second region 120 of the polarizing plate 100 is disposed between the display panel 150 and the cover glass 200. The display panel 150 includes a light emitting diode 152 for displaying an image. Therefore, the first region 110 and the second region 120 are included in an image display region.

[0043] The optical display device is provided with an image sensor 250 arranged below the display panel 150 and corresponding to the first area 110. Thus, the first area 110 can realize an image display function by suppressing visual observation of the image sensor outside without using the image sensor 250, while improving the image capture resolution by the image capture function of the image sensor 250 when using the image sensor 250. With a light transmittance of 50% to 80%, in the optical display device, the first area 110 can realize all the above effects in the laminate of the image sensor 250-the display panel 150 including the light emitting diode-the polarizing plate 100.

[0044] The first region 110 may occupy an area ratio of 10% or less in the polarizing plate, preferably in the entirety of the first region 110 and the second region 120. Within this range, the first region may provide an image sensor function.

[0045] The first region 110 may have a circular, oval, angled, or amorphous shape, but is not limited thereto.

[0046] In the polarizing plate, the first region 110 may be placed at any position without limitation, and may be placed corresponding to the position of the image sensor 250 in the optical display device.

[0047] The first area 110 may allow the effect of the present invention to be more effectively achieved by adjusting the color values ​​a* and b* in the color coordinates. That is, the first area 110 needs to allow the image to be displayed continuously with the second area 120 while allowing the image to be captured more clearly when using the image sensor. To this end, the transmittance of the first area 110 is adjusted together with the color values ​​a* and b*.

[0048] In one embodiment, in color coordinates, the first region may have a color value a* of about -13 to about 2 (e.g., -13, -12, -11, -10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 0, 1, or 2), preferably about -10 to about 2, more preferably about -4 to about 2, and a color value b* of about 1 to about 35 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, or 35), preferably about 15 to about 35. Within this range, the first region allows an image to be continuously displayed together with the second region 120, while allowing the image to be captured more clearly when using an image sensor.

[0049] The “color coordinates” can be obtained by a color coordinate evaluation method according to the CIE 1976 L*a*b* values.

[0050] Next, a method of manufacturing a polarizing plate including the first region 110 and the second region 120 according to one embodiment of the present invention will be described.

[0051] The polarizing plate according to the present invention can be manufactured by the following steps: preparing a laminate of a polarizer (not formed with the first region and the second region) and a protective layer formed on at least one surface of the polarizer (not formed with the first region and the second region), and then irradiating a predetermined region of the laminate with a pulsed UV laser beam having a wavelength of about 200nm to about 1000nm to form a first region. The region of the laminate that is not irradiated by the pulsed UV laser beam becomes the second region. Irradiation with a pulsed UV laser beam having a wavelength of about 200nm to about 1000nm can form a first region having a transmittance of about 50% to about 80%, while achieving the above-mentioned color coordinates.

[0052] The polarizer (not formed with the first region and the second region) includes a polyvinyl alcohol film dyed with iodine and / or a dichroic dye and stretched. The polarizer (not formed with the first region and the second region) can have a thickness of about 3 μm to about 50 μm, specifically, about 3 μm to about 30 μm. Within this range, the polarizer can be used in the polarizing plate.

[0053] The polarizer (without the first region and the second region formed thereon) may be manufactured by a typical method known to those skilled in the art.

[0054] First, a dyed and stretched polyvinyl alcohol film was produced.

[0055] The dyed and stretched polyvinyl alcohol film can be manufactured by dyeing, stretching, cross-linking and color correction processes. In the method for manufacturing a polarizer according to the present invention, dyeing and stretching can be performed in any order. That is, the polyvinyl alcohol film can be dyed and then stretched, or vice versa, or dyeing and stretching can be performed simultaneously.

[0056] The polyvinyl alcohol film may be a typical polyvinyl alcohol film used in the manufacture of a typical polarizer. Specifically, the polyvinyl alcohol film may be a film produced from polyvinyl alcohol or a derivative thereof. The polyvinyl alcohol film may have a degree of polymerization of about 1,000 to about 5,000, a degree of saponification of about 80 mol% to about 100 mol%, and a thickness of about 1 μm to about 30 μm, specifically about 3 μm to about 30 μm. Within this range, the polyvinyl alcohol film may be used to manufacture a thin polarizer.

[0057] The polyvinyl alcohol film can be washed with water and swelled before dyeing and stretching. The polyvinyl alcohol film can be washed with water to remove foreign matter from the surface of the polyvinyl alcohol film. The polyvinyl alcohol film can be subjected to swelling to allow more effective dyeing or stretching of the polyvinyl alcohol film. Swelling can be achieved by leaving the polyvinyl alcohol film in an aqueous solution of a swelling bath, as is well known to those skilled in the art. The temperature and swelling time of the swelling bath are not particularly limited. The swelling bath can further include boric acid, an inorganic acid, a surfactant, etc., and the content of these components can be adjusted.

[0058] The polyvinyl alcohol film can be dyed by immersing the polyvinyl alcohol film in a dyeing bath containing iodine and / or dichroic dyes. During the dyeing process, the polyvinyl alcohol film is immersed in a dyeing solution, which can be an aqueous solution containing iodine and / or dichroic dyes. Specifically, iodine is provided in the form of an iodine-based dye. Iodine-based dyes can include at least one selected from potassium iodide, hydrogen iodide, lithium iodide, sodium iodide, zinc iodide, lithium iodide, aluminum iodide, lead iodide and copper iodide. The dyeing solution can be an aqueous solution containing about 1wt% to about 5wt% of iodine and / or dichroic dyes. Within this range, the polarizer has a degree of polarization within a predetermined range used in a display device.

[0059] The dyeing bath may have a temperature of about 20° C. to about 45° C., and the polyvinyl alcohol film may be immersed in the dyeing bath for about 10 seconds to about 300 seconds. Within this range, a polarizer having a high degree of polarization may be realized.

[0060] The dyed polyvinyl alcohol film can be stretched in a stretching bath to exhibit polarization through the orientation of iodine and / or dichroic dyes. Specifically, stretching can be achieved by dry stretching and wet stretching. Dry stretching can be performed by roller stretching, compression stretching, hot roller stretching, etc., and wet stretching can be performed in a wet stretching bath containing water at about 35°C to about 65°C. The wet stretching bath may further contain boric acid to improve the stretching effect.

[0061] The polyvinyl alcohol film can be stretched at a certain stretching ratio, specifically about 5 times to about 7 times, more specifically about 5.5 times to about 6.5 times. Within this range, the polyvinyl alcohol film can prevent cutting, wrinkling, etc. during stretching, and a polarizer with improved polarization degree and transmittance can be achieved. Stretching can be performed by uniaxial stretching via single-stage stretching or multi-stage stretching (such as double-stage stretching and three-stage stretching), thereby preventing the rupture of the polyvinyl alcohol film in the manufacture of a thin polarizer.

[0062] Although dyeing and stretching of the polyvinyl alcohol film are performed in the order described in the above-mentioned examples, dyeing and stretching may be performed in the same reaction bath.

[0063] Before or after stretching the dyed polyvinyl alcohol film, the polyvinyl alcohol film may be subjected to crosslinking in a crosslinking bath. Crosslinking is a method that allows the polyvinyl alcohol film to be more intensely dyed with iodine and / or dichroic dyes, and can be performed using boric acid as a crosslinking agent. In order to enhance the crosslinking effect, the crosslinking bath may further contain a phosphoric acid compound, potassium iodide, etc.

[0064] The dyed and stretched polyvinyl alcohol film may be subjected to color correction in a color correction bath. In the color correction, the dyed and stretched polyvinyl alcohol film is immersed in a color correction bath filled with a color correction solution containing potassium iodide. As a result, the polarizer has a reduced color value and iodine ions (I 2 ) are removed from the polarizer. - ), thereby improving durability. The color correction bath may have a temperature of about 20° C. to about 45° C., and the polyvinyl alcohol film may be immersed therein for about 10 seconds to about 300 seconds.

[0065] Next, a laminate is manufactured by forming a protective layer on at least one surface of the dyed and stretched polyvinyl alcohol film. The protective layer can be manufactured by a typical method known to those skilled in the art.

[0066] The protective layer is formed on at least one surface of the polarizer and may be a photocurable coating or a protective film.

[0067] The protective film may be a typical protective film used as a protective film of a polarizer. For example, the protective film may include a protective film formed by at least one resin selected from cellulose resins including triacetyl cellulose, polyester resins including polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, etc., cyclic polyolefin resins, polycarbonate resins, polyether sulfone resins, polysulfone resins, polyamide resins, polyimide resins, polyolefin resins, polyarylate resins, polyvinyl alcohol resins, polyvinyl chloride resins, and polyvinylidene chloride resins. The protective film may have a thickness of about 10 μm to about 100 μm, for example, about 10 μm to about 60 μm. Lamination may be performed using an adhesive according to typical methods known to those skilled in the art.

[0068] Thereafter, the first region is formed by irradiating a predetermined region of the laminate with a pulsed UV laser beam at a wavelength of about 200 nm to about 1000 nm.

[0069] The wavelength of the pulsed UV laser is in the range of about 200nm to 1000nm. By transferring the iodine and dichroic pigments from the ground state to the excited state, the iodine and dichroic pigments in the polarizer are decomposed, thereby increasing the transmittance of the irradiated area.

[0070] However, even after irradiation with a pulsed UV laser beam having a wavelength ranging from about 200 nm to about 1,000 nm, a dichroic substance such as iodine and a dichroic dye exists in a region of the polarizer corresponding to the first region.

[0071] In one embodiment, the first region can have an iodine content of about 0.01 wt % to about 5 wt % (e.g., 0.01 wt %, 0.02 wt %, 0.03 wt %, 0.04 wt %, 0.05 wt %, 0.06 wt %, 0.07 wt %, 0.08 wt %, 0.09 wt %, 0.1 wt %, 0.2 wt %, 0.3 wt %, 0.4 wt %, 0.5 wt %, 0.6 wt %, 0.7 wt %, 0.8 wt %, 0.9 wt %, 1 wt %, 2 wt %, 3 wt %, 4 wt %, or 5 wt %), specifically about 0.01 wt % to about 1 wt %. Within this range, the first region can improve transmittance while minimizing dichroism. "Iodine content" can refer to iodine (I2) and iodide ions (I - ,I3 - ,I5 - The content of all iodine-containing substances including

[0072] The present invention is different from the typical method in the art of increasing the transmittance above about 80% by completely removing the dichroic substances (such as iodine and dichroic dyes) in the polarizer by treating the polarizer with an acid or alkaline solution. In addition, the present invention is different from the typical method in the prior art of forming a region with higher transmittance on the polarizer by treating the polarizer with a femtosecond or nanosecond laser beam in that no post-processing is required after irradiation, and the boundary between the first region and the second region is clear.

[0073] Specifically, the irradiation may be performed using a pulsed laser beam having a wavelength ranging from about 200 nm to about 1,000 nm, preferably from about 200 nm to about 800 nm.

[0074] The pulsed laser beam in the wavelength range of about 200 nm to about 1,000 nm may be emitted at a voltage of about 400 V to about 750 V. The pulsed laser beam in the wavelength range of about 200 nm to about 1,000 nm may be emitted with a pulse period (one irradiation time) of 300 μs to about 600 μs. The pulsed laser beam in the wavelength range of about 200 nm to about 1,000 nm may be emitted at a power of about 2.0 J / cm 2 To about 5.0J / cm 2 The above-mentioned pulse laser has a wavelength range of 200nm-1000nm and can emit 5kw / cm 2 -30kw / cm 2Intensity is emitted. Within this range, the first region can achieve a transmittance of about 50% to about 80% without carbonizing the treated surface of the polarizer by heating. "Energy density" refers to the irradiation energy per pulse per unit area in a region of the polarizer with high transmittance.

[0075] In one embodiment, irradiation with a pulsed laser beam having a wavelength ranging from about 200 nm to about 1,000 nm at a pulse period of about 460 μs may be performed for about 0.4 seconds to about 400 seconds, for example, about 1 second to about 40 seconds. Within this range, a neutral colorless region having high transmittance can be formed without thermal deformation of the polarizer and the protective film by increasing the irradiation time or the number of irradiations under the above conditions.

[0076] Irradiation with a pulsed laser beam having a wavelength ranging from about 200 nm to about 1,000 nm may be performed once to 20 times. Within this range, a neutral colorless region having high transmittance can be formed without thermal deformation of the polarizer and the protective film by increasing the irradiation time or the number of irradiations under the above conditions.

[0077] The polarizer formed with the first region and the second region may have a thickness of about 3 μm to about 50 μm, specifically, about 3 μm to about 30 μm. Within this range, the polarizer may be used in a polarizing plate.

[0078] Next, a method of manufacturing a polarizing plate including the first region 110 and the second region 120 according to another embodiment of the present invention will be described.

[0079] The polarizing plate according to the present invention can be manufactured by the following steps: irradiating a predetermined area of ​​the polarizer (not formed with the first area and the second area) with a pulsed UV laser beam having a wavelength of about 200 nm to about 1000 nm to form a first area, and then forming a protective layer on at least one surface of the polarizer. The prescribed area of ​​the polarizer irradiated by the pulsed UV laser beam becomes the first area, and the area of ​​the polarizer not irradiated by the pulsed UV laser beam becomes the second area. The method according to this embodiment is substantially the same as the method according to the above embodiment, except that the polarizer (not formed with the first area and the second area) is irradiated with a pulsed UV laser beam instead of irradiating the laminate of the polarizer and the protective layer.

[0080] Next, an optical display device according to one embodiment of the present invention will be described.

[0081] The optical display device according to the present invention includes the polarizing plate according to the present invention. The optical display device may include an organic light emitting diode display, etc.

[0082] Will refer to Figure 1 The optical display device according to the present invention is described in more detail.

[0083] Reference Figure 1 The optical display device includes: a display panel 150 including a base layer 151 and a light emitting diode 152; a polarizing plate 100 formed on the display panel 150; a cover glass 200 formed on the polarizing plate 100; and an image sensor 250 disposed below the display panel 150.

[0084] The polarizing plate 100 includes a first region 110 and a second region 120. The polarizing plate includes the polarizing plate according to the present invention. The first region 110 and the second region 120 both constitute an image display region of an optical display device.

[0085] The first region 110 is less densely provided with the light emitting diodes 151 than the second region 120. With this structure, the first region can realize an image display function through the image sensor 250 and realize an image display function through the display panel 150 at the same time.

[0086] The image sensor 250 is disposed under the first region 110. The image sensor 250 may include a camera, but is not limited thereto.

[0087] Next, the present invention will be described in more detail with reference to some examples. However, it should be noted that these examples are provided for illustration only and should not be interpreted as limiting the present invention in any way.

[0088] The details of the components used in Examples and Comparative Examples are as follows.

[0089] (1) Polarizer material: Polyvinyl alcohol film (VF-PE3000, thickness: 30 μm, Kuraray Co., Ltd., Japan)

[0090] (2) Protective film: triacetyl cellulose film (KC4UYW, thickness: 40 μm, Konica Co., Ltd., Japan)

[0091] Example 1

[0092] The polyvinyl alcohol film washed with water was subjected to swelling treatment at 30°C in a swelling bath filled with water.

[0093] After the swelling treatment, the polyvinyl alcohol film was dyed with an aqueous solution containing 3 wt% potassium iodide in a dyeing bath at 30°C for 30 to 200 seconds. At 30°C to 60°C, the dyed polyvinyl alcohol film was passed through a wet crosslinking bath filled with an aqueous solution containing 3 wt% boric acid. Thereafter, the polyvinyl alcohol film was stretched in an aqueous solution containing 3 wt% boric acid at 50°C to 60°C to a total stretching ratio of 6 times its initial length, thereby preparing a polarizer. A laminate was prepared by bonding a protective film to both surfaces of the prepared polarizer using an adhesive (Z-200, NipponGoshei Co., Ltd.).

[0094] The laminate was cut into a predetermined size, and a target area of ​​the first region of the laminate was irradiated with a pulsed UV laser beam at a wavelength of 200 nm to 800 nm under the conditions listed in Table 1, thereby manufacturing a polarizing plate formed with the first region. The region of the polarizing plate not irradiated with the pulsed UV laser beam became the second region.

[0095] Examples 2 to 4

[0096] Polarizing plates each having a first region and a second region were manufactured in the same manner as in Example 1, except that, as listed in Table 1, the conditions for irradiation with a pulsed UV laser beam were changed.

[0097] Comparative Example 1

[0098] A polarizing plate having a first region and a second region was manufactured in the same manner as in Example 1, except that, as listed in Table 2, the conditions for irradiation with a pulsed UV laser beam were changed.

[0099] Comparative Example 2

[0100] A polarizing plate having a first region and a second region was manufactured in the same manner as in Example 1, except that, as listed in Table 2, the conditions for irradiation with a pulsed UV laser beam were changed.

[0101] Comparative Example 3

[0102] A polarizing plate was manufactured in the same manner as in Example 1, except that the first region was formed by a chemical method. The protective film was removed from the polarizer of Example 1, and a surface mask having a circular through hole with a diameter of 50 mm was bonded to the exposed surface of the polarizer. The polarizer was immersed in a 5 mol / L aqueous sodium hydroxide solution (alkaline aqueous solution) for 7 seconds. Thereafter, the polarizer was immersed in 0.1 m / l hydrochloric acid. The resulting product was dried in an oven at 60°C, and the surface mask was subsequently removed therefrom. As a result, a polarizer having a first region was prepared. A polarizing plate was manufactured by bonding a PET film having a 5 μm thick adhesive layer as a surface protective film to a polarizer. In the polarizing plate, the first region had a transmittance of 91.71%. Even with different alkaline aqueous solutions, a polarizer having a transmittance of greater than 80% can be obtained.

[0103] Comparative Example 4

[0104] A polarizing plate was manufactured in the same manner as in Example 1, except that the first region was formed by punching a corresponding portion of the polarizing plate using a laser cutter.

[0105] The following properties of the polarizing plates manufactured in the Examples and Comparative Examples were evaluated, and the evaluation results are shown in Tables 1 and 2 and Figure 3 middle.

[0106] (1) Light transmittance of first region and second region (unit: %): Light transmittance was measured at a wavelength of 550 nm on each of the first region and the second region of each polarizing plate manufactured in Examples and Comparative Examples using JASCO V730.

[0107] (2) Polarization degree of first region and second region (unit: %): The polarization degree was measured at a wavelength of 550 nm on each of the first region and the second region of each polarizing plate manufactured in Examples and Comparative Examples using JASCO V730.

[0108] (3) Color values ​​a* and b* in color coordinates of the first region: Color values ​​were measured on the first region of each of the polarizing plates manufactured in Examples and Comparative Examples using a UV-VIS spectrophotometer V7100 (JASCO).

[0109] (4) Visual observation of camera and image resolution of camera: Visual observation of camera and the resulting image were observed above the polarizing plate using a camera disposed below the first region of each polarizing plate. Polarizing plates that provided a difference in polarization degree between the first region and the second region without visual observation of the camera lens while providing a high-resolution image through the camera were rated as ◎, polarizing plates that allowed observation through the camera lens while providing a high-resolution image through the camera were rated as X1, and polarizing plates that did not provide a difference in polarization degree between the first region and the second region and provided a low-resolution image through the camera were rated as X2.

[0110] Table 1

[0111]

[0112] Table 2

[0113]

[0114]

[0115] As shown in Table 1, when applied to an optical display device, the polarizing plate according to the present invention can perform an image display function by suppressing visual observation of an image sensor outside when the image sensor is not used, while increasing the resolution of the image when the image sensor is used. Figure 3 As shown, since the first area is not easily observed with the naked eye during black screen output, the polarizing plate according to the present invention does not suffer from failure of the image display function. Figure 3 , which shows three circular color coordinate evaluation images, the leftmost image is the evaluation result of the polarizing plate manufactured in Example 1.

[0116] In contrast, as shown in Table 2, although the polarizing plate of Comparative Example 1 including the first region having a transmittance of external light according to the present invention does not allow observation by the image sensor, the polarizing plate has a problem in that the image sensor cannot recognize external light. Figure 3 As shown, the polarizing plates of Comparative Examples 1 and 2 allow the first region to be easily observed during the output of the black screen. In addition, the polarizing plate of Comparative Example 3 having a high light transmittance region formed by a typical chemical method and the polarizing plate of Comparative Example 4 using a typical stamping method cannot provide the effects of the present invention.

[0117] It should be understood that various modifications, changes, variations and equivalent embodiments may be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. A polarizing plate, comprising: Polarizers; and a protective layer formed on at least one surface of the polarizer, The polarizing plate includes a first area and a second area within the image display area. The first region and the second region have different light transmittances at the same wavelength. The first region has a light transmittance of 50% to 80%, a color value a* of -13 to 2, and a color value b* of 1 to 35, wherein the first region has a polarization degree of 25% to 80%, The second region has a light transmittance of 40% to less than 50%, and the light transmittance difference between the first region and the second region is in the range of 5% to 30%.

2. The polarizing plate according to claim 1, wherein The first region has an iodine content of 0.01 wt % to 5 wt %.

3. The polarizing plate according to claim 1, wherein The first area has an image display function and an image capturing function. 4 . An optical display device comprising the polarizing plate according to claim 1 .

Images