TW201539052A - Polarizer and image display device - Google Patents

Abstract

According to one embodiment of the invention, a polarizer of an image display device capable of realizing excellent camera performance is provided. The polarizer of the embodiment of the invention is formed of a resin film containing a dichroic substance, and has a decolorization part that is partially decolorized.

Description

Polarizing element and image display device

The present invention relates to a polarizing element and an image display device.

An image display device such as a mobile phone or a notebook personal computer (PC) is usually equipped with a camera. Various studies have been conducted in order to improve the camera performance of such an image display device (for example, Patent Document 1). However, with the rapid spread of smart phones and touch panel type information processing devices, the industry expects to further improve camera performance.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2011-81315

The present invention has been made to solve the above-mentioned problems, and a main object thereof is to provide a polarizing element which can realize an image display device excellent in camera performance.

The inventors of the present invention have focused on a polarizing element mounted on an image display device, and have found that the above object can be attained by forming a decolorizing portion by a polarizing element, thereby completing the present invention.

The polarizing element of the present invention is composed of a resin film containing a dichroic substance and has a partially decolored portion.

In one embodiment, the transmittance of the decolorizing unit is 46% or more.

In one embodiment, the decolorizing unit irradiation includes at least a wavelength of at least 1500 nm. The laser light of the wavelength is formed by laser light.

In one embodiment, the decolorizing unit corresponds to a camera hole portion of the image display device mounted.

In one embodiment, the dichroic material is iodine.

In one embodiment, the polarizing element has a thickness of 30 μm or less.

According to another aspect of the present invention, a method of fabricating a polarizing element is provided. The method for producing a polarizing element includes the step of irradiating a resin film containing a dichroic substance with laser light to form a decolorizing portion.

In one embodiment, the laser light comprises light having a wavelength of at least 1500 nm.

In one embodiment, the laser is a solid laser.

According to still another aspect of the present invention, an image display device is provided. This image display device includes the above-described polarizing element.

According to still another aspect of the present invention, a method of manufacturing the above image display device is provided. The manufacturing method includes the step of irradiating laser light onto an image display panel in which a resin film containing a dichroic material is formed on the surface side to form the decolorizing portion.

According to the present invention, the formation of the decolorizing portion by the resin film containing the dichroic material ensures the transparency of the camera hole portion and contributes to an improvement in the camera performance of the obtained image display device. Thus, according to the present invention, not only a receiving type electronic device such as an image or a monitor (for example, a camera device having a photographic optical system) but also a transmitting type electronic device such as an LED light or an infrared sensor can be provided and the transmission to the naked eye can be ensured. Sexual image display device.

1‧‧‧Polarized elements

2‧‧‧Decolorization Department

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view showing a polarizing element according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to the embodiments.

A. Polarized component

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view showing a polarizing element of a preferred embodiment of the present invention. The polarizing element 1 is a decolorizing unit 2 which is composed of a resin film and partially decolored. According to this configuration, it is possible to avoid cracking and delamination as compared with the case where a hole is formed in a resin film (specifically, a method of mechanical cutting by a dicing blade or a water jet using a water jetter or the like). Quality problems such as interlayer peeling and paste spillage.

The above resin film contains a dichroic substance. Examples of the dichroic substance include iodine, an organic dye, and the like. These may be used singly or in combination of two or more. It is preferred to use iodine. The iodine is irradiated with a specific laser as described below, and its complex with a resin constituting the resin film (for example, a polyvinyl alcohol-based resin) is disintegrated in an appropriate ratio, and as a result, it can be formed to have a suitable shape for use as a camera hole. Decolorizing part of the characteristics.

As the resin forming the above resin film, any appropriate resin can be used. It is preferable to use a polyvinyl alcohol-based resin (hereinafter referred to as "PVA-based resin"). As described above, the PVA-based resin and the iodine complex are disintegrated in an appropriate ratio by irradiation with a specific laser, and as a result, a decolorizing portion having characteristics suitable for use as a camera hole can be formed. Examples of the PVA-based resin include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer is obtained by saponifying an ethylene-vinyl acetate copolymer. The saponification degree of the PVA-based resin is usually 85 mol% or more and less than 100 mol%, preferably 95.0 mol% to 99.95 mol%, and further preferably 99.0 mol% to 99.93 mol%. The degree of saponification can be determined in accordance with JIS K 6726-1994. By using such a saponification degree PVA-based resin, a polarizing element excellent in durability can be obtained. When the degree of saponification is too high, there is a tendency to cause gelation.

The average degree of polymerization of the PVA-based resin can be appropriately selected depending on the purpose. The average degree of polymerization is usually from 1,000 to 10,000, preferably from 1200 to 4,500, and more preferably from 1,500 to 4,300. again The average degree of polymerization can be determined in accordance with JIS K 6726-1994.

It is preferable that the polarizing element (excluding the decolorizing section) exhibits absorption dichroism in a wavelength range of 380 nm to 780 nm. The monomer transmittance (Ts) of the polarizing element (excluding the decolorizing unit) is preferably 40% or more, more preferably 41% or more, further preferably 42% or more, and particularly preferably 43% or more. Furthermore, the theoretical upper limit of the monomer transmittance is 50%, and the practical upper limit is 46%. Further, the monomer transmittance (Ts) is a Y value measured by a 2 degree field of view (C light source) of JIS Z8701 and corrected by visibility, and can be measured, for example, using a microscopic spectroscopic system (manufactured by Lambda Vision, LVmicro). The degree of polarization of the polarizing element (excluding the decolorizing unit) is preferably 99.8% or more, more preferably 99.9% or more, still more preferably 99.95% or more.

The thickness of the polarizing element can be set to any appropriate value. The thickness is typically about 1 μm to 80 μm, preferably 30 μm or less. The thinner the thickness, the better the decolorizing portion can be formed. For example, in the following laser light irradiation, the absorbance per unit film thickness is high, and the decolorizing portion can be formed efficiently.

In the example of the drawing, a small circular discolored portion 2 is formed at the center portion of the upper end portion of the resin film, but the arrangement, shape, size, and the like of the decolorizing portion can be appropriately designed. It is preferable to design according to the position, shape, size, and the like of the camera hole portion of the mounted image display device. Specifically, the design is performed such that the decolorizing unit does not correspond to the display screen of the mounted image display device.

The transmittance of the decolorizing section (for example, the transmittance measured by light having a wavelength of 550 nm at 23 ° C) is preferably 46% or more, more preferably 60% or more, still more preferably 75% or more, and particularly preferably 90. %the above. If it is such a transmittance, the transparency required as a discoloring part can be ensured. As a result, when the decolorizing section is used as the camera hole portion of the image display device, it is possible to prevent adverse effects on the photographic performance of the camera.

The polarizing element of the present invention can be used in any suitable form. Typically, the polarizing element is used at least on its one-sided laminated protective film (as a polarizing film). Examples of the material for forming the protective film include cellulose systems such as diethyl cellulose and triacetyl cellulose. Resin, (meth)acrylic resin, cycloolefin resin, olefin resin such as polypropylene, ester resin such as polyethylene terephthalate resin, polyamine resin, polycarbonate resin, Such as copolymer resin and the like.

It is also possible to perform a hard coat layer or an anti-reflection treatment as a surface treatment layer on the surface of the unshielded polarizing element of the protective film, and to treat it by diffusion or anti-glare. For the surface treatment layer, for example, a layer having a low moisture permeability for the purpose of improving the humidifying durability of the polarizing element is preferable. The hard coat treatment is carried out in order to prevent damage or the like on the surface of the polarizing film. The hard coat layer can be formed, for example, by attaching a hardened film excellent in hardness or sliding properties such as an acrylic or polyoxynitrene-based resin to a surface of a polarizing film. As the hard coat layer, the pencil hardness is preferably 2 H or more. The anti-reflection treatment is carried out in order to prevent reflection of external light on the surface of the polarizing film, and can be achieved by forming a low-reflection layer according to the prior type or the like, that is, for example, disclosed in Japanese Laid-Open Patent Publication No. 2005-248173 A thin layer type in which the effect of the reflected light is removed by the action of the light, and the reflection is prevented, or a structure having a low reflectance is exhibited by imparting a fine structure to the surface as disclosed in Japanese Laid-Open Patent Publication No. 2011-2759. The anti-glare treatment is carried out in order to prevent external light from being reflected on the surface of the polarizing film and to prevent the polarizing film from being transmitted through the light. For example, it may be a suitable method such as a roughening method by a sand blasting method or an embossing method or a method of blending transparent fine particles. This is carried out by imparting a fine concavo-convex structure to the surface of the protective film. The anti-glare layer may also function to diffuse the polarizing film through the light to expand the diffusion layer (such as a viewing angle expansion function).

The thickness of the protective film is preferably from 20 μm to 100 μm. The protective film is typically laminated on the polarizing element via an adhesive layer (specifically, an adhesive layer or an adhesive layer). The adhesive layer is typically formed of a PVA-based adhesive. The adhesive layer is typically formed of an acrylic adhesive.

B. Method of manufacturing polarizing element

The polarizing element is preferably produced by subjecting a resin film containing a dichroic material to a decolorizing treatment to form the decolorizing portion.

The resin film containing the dichroic substance is preferably produced by subjecting the resin film to dyeing or the like. Further, the resin film may be a resin layer (PVA-based resin layer) formed on the resin substrate. According to this aspect, a polarizing element having a small thickness (for example, 10 μm or less) can be obtained.

B-1. Dyeing

The above dyeing is preferably carried out by adsorbing iodine to the resin film. Examples of the adsorption method include a method of immersing a resin film in a dyeing liquid containing iodine, a method of applying the dyeing liquid to a resin film, and a method of spraying the dyeing liquid onto a resin film in a mist form. A method of immersing the resin film in the dyeing liquid is preferred. The reason for this is that iodine can be adsorbed well.

The above dyeing liquid is preferably an aqueous iodine solution. The amount of iodine to be added is preferably from 0.04 parts by weight to 5.0 parts by weight based on 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferred to formulate an iodide in an aqueous iodine solution. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, cesium iodide, calcium iodide, tin iodide, titanium iodide, and the like. . Among these, potassium iodide is preferred. The amount of the iodide compounded is preferably from 0.3 part by weight to 15 parts by weight per 100 parts by weight of the water.

The liquid temperature of the dyeing solution during dyeing is preferably from 20 ° C to 50 ° C. When the PVA-based resin film is immersed in the dyeing liquid, the immersion time is preferably from 5 seconds to 5 minutes.

B-2. Other treatment

The resin film may be subjected to a treatment for forming a polarizing element in addition to dyeing. Examples of the treatment for forming the polarizing element include an extension treatment, an insolubilization treatment, a crosslinking treatment, a cleaning treatment, and a drying treatment. Further, the number, order, and the like of the processes are not particularly limited.

As an extension method of the above extension processing, any appropriate method can be employed. Specifically, it may be a free end extension or a fixed end extension.

The direction of extension can be set as appropriate. In one embodiment, the resin film extends in the longitudinal direction of the elongated resin film. In this case, it is representative that the resin film is passed through the circle. A method of extending between rolls having different circumferential speeds. In another embodiment, the resin film extends in the width direction of the elongated resin film. In this case, a method of stretching using a tenter stretching machine is representative. Further, the extending direction may correspond to the absorption axis direction of the obtained polarizing element.

The stretching method is not particularly limited and may be either wet or dry. The extension temperature is appropriately set, for example, by a stretching method.

Regarding the stretching ratio, it is typically 3 to 7 times. The extension can be carried out in one stage or in multiple stages. In the case of extending in multiple stages, for example, the free end extension and the fixed end extension may be combined, and the wet extension and the dry extension may be combined. Furthermore, in the case of extending in multiple stages, the above-described stretching ratio is the product of the stretching ratios of the respective stages.

As described above, in the case where the resin film is a resin layer (PVA-based resin layer) formed on the resin substrate, it is preferred to combine dry stretching and wet stretching. More specifically, it is preferred to dry-extend the laminate of the resin substrate and the resin layer (resin film), and further perform wet stretching in a boric acid aqueous solution. Further, specific examples of the resin substrate and detailed extension conditions are described, for example, in Japanese Patent No. 4804588. This description is incorporated herein by reference.

The insolubilization treatment and the crosslinking treatment are typically carried out by immersing the resin film in an aqueous boric acid solution. The cleaning treatment is typically carried out by immersing the resin film in an aqueous solution of potassium iodide. The drying temperature in the above drying treatment is preferably from 30 ° C to 100 ° C.

B-3. Decolorization

It is preferable that the decolorizing unit is formed by irradiating the resin film containing the dichroic substance with laser light. By the irradiation of the laser light, the decolorizing portion having a desired shape can be favorably formed at a desired position. More specifically, in recent years, according to design requirements, it is strongly required to make the non-image display portion of the image display device as small as possible, and as a result, the decolorizing portion is used as a camera. In the case of a hole, it is necessary to form a decolorizing portion at the extreme end portion (for example, the uppermost end central portion) of the polarizing element. In this case, if a hole is to be mechanically formed as a camera hole instead of the decolorizing portion, the end portion of the polarizing film may be formed into a slit. As a result, it is not possible to use it as a polarizing film from the viewpoint of mechanical strength or the viewpoint of commercial value. This kind of malfunction can be prevented by laser irradiation. Moreover, even if the protective film is laminated on the resin film as described above, the decolorizing portion can be formed. Further, it is also excellent in mass productivity.

The above laser light is preferably light containing a wavelength of at least 1500 nm or less. The decolorizing portion can be formed by including laser light of such a wavelength. More preferably, it is light having a wavelength of at least 1000 nm or less, further preferably light having a wavelength of 800 nm or less, and particularly preferably light having a wavelength of 600 nm or less. By including laser light of such a wavelength, surface uniformity can be achieved and a discoloration portion can be formed. Specifically, the decolorizing portion can be formed without causing damage (for example, thermal deformation) to the optical member (for example, the protective film) around the polarizing element. Further, it is considered that one of the main causes of damage to the optical member around the polarizing element is that the difference in absorbance between the polarizing element and its peripheral optical member is reduced. Further, the decolorizing portion can be favorably formed without causing damage to the resin film itself. As a result, the planarity of the obtained image display device (image display panel) can be ensured, and a good module design can be achieved. Further, by including the laser light of the above wavelength, the transmittance of the decolorizing portion can be satisfactorily achieved.

Examples of the laser include a YAG (Yttrium Aluminum Garnet) laser, a YLF (Yttrium Lithium Fluoride) laser, a YVO4 laser, and the like, and an argon ion laser. , 氪 ion laser gas laser, fiber laser, semiconductor laser. It is preferred to use a solid laser (especially a YAG laser).

As the above-described laser, it is preferable to use a short-pulse laser (a laser that emits light having a pulse width of 1 nm or less, such as a picosecond laser or a femtosecond laser). In order to suppress thermal damage to the resin film, a pulse width of 500 picoseconds or less is particularly preferable.

The irradiation conditions of the laser light can be set to any appropriate conditions. For example, using solids In the case of a laser (YAG laser), the pulse energy is preferably 25 μJ to 71 μJ. The scanning speed is preferably from 10 mm/sec to 100 mm/sec. The pulse repetition rate is preferably from 100 Hz to 12480 Hz. According to such a condition, the decolorizing portion can be favorably formed without causing damage to the polarizing film peripheral member or the resin film itself. Moreover, the above transmittance can be satisfactorily achieved.

Preferably, the laser light includes a polarized light that is substantially coaxial with an absorption axis of the resin film (polarizing element). With such laser light, the difference in absorbance between the polarizing element and its peripheral optical member can be further increased, and the decolorizing portion can be formed more satisfactorily.

At the time of the above irradiation, for example, a galvanometer mirror can be driven to scan and position the laser. Moreover, in order to obtain the uniformity of the surface of the decolorizing section, etc., a homogenizer (DOE: Diffractive Optical Element) which uniformizes the intensity of the laser light mainly having a Gaussian distribution may be used.

Further, by irradiating X-rays, surface uniformity can be achieved, and the above-described decolorizing portion can be favorably formed. Alternatively, the decolorizing unit may be formed by, for example, a light source that emits light having a wavelength of 100 pm to 1500 nm (for example, a xenon (Xe) lamp) or a heating plate for a bar code printing.

C. Image display device

The image display device of the present invention includes the above-described polarizing element. Examples of the image display device include a liquid crystal display device and an organic EL device. Specifically, the liquid crystal display device includes a liquid crystal panel including a liquid crystal cell and the above-described polarizing element disposed on one side or both sides of the liquid crystal cell. The organic EL device includes an organic EL panel in which the above-described polarizing element is disposed on the viewing side. The polarizing element is disposed such that the decolorizing portion corresponds to the camera hole portion of the mounted image display device.

D. Method of manufacturing image display device

In one embodiment, the image display device is manufactured by stacking an image display panel (for example, a liquid crystal panel or an organic layer) so that the resin film containing the dichroic material is formed on the surface side. EL panel), (from the surface side) illuminates the laser light The above-described decolorizing portion is formed. By this method, the positioning of the decolorizing section can be made easy.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by the examples. Furthermore, the measurement method of the transmittance is as follows.

[Transmission rate (Ts)]

The measurement was carried out using a microscopic spectroscopic system (Lambda Vision Co., Ltd., LVmicro). Further, Ts is a Y value measured by a 2 degree field of view (C light source) of JIS Z8701 and corrected by visibility.

[Example 1]

Using a solid laser (wavelength: 532 nm), with a pulse energy of 40 μJ, a scanning speed of 100 mm/sec, and a pulse repetition rate of 3,120 Hz, a polarizing film of a paste having a total thickness of 129 μm was observed from the side (the first protective film side). (Adhesive layer (thickness: 20 μm) / second protective film (thickness: 58 μm) / polarizing element (thickness: 5 μm) / first protective film (thickness: 46 μm)) irradiated with laser light.

In the above manner, a decolorizing portion is formed on the polarizing film (polarizing element).

Successfully only decolorizes the area illuminated by the laser light. The transmittance of the unirradiated portion was 44.0%, and the transmittance of the irradiated portion was 66.2%.

Moreover, the surface shape of the irradiation region was confirmed by WYKO (manufactured by Bruker AXS Co., Ltd.), and as a result, there was no significant step or unevenness, and the surface uniformity was excellent. Further, the inside of the polarizing film was observed by visual observation, and as a result, cracking such as cracking was not confirmed.

[Embodiment 2]

A decolorizing section was formed in the same manner as in Example 1 except that the laser light was irradiated with irradiation conditions of a pulse energy of 71 μJ, a scanning speed of 100 mm/sec, and a pulse repetition rate of 6240 Hz.

Successfully only decolorizes the area illuminated by the laser light. The transmittance of the unirradiated portion was 44.0%, and the transmittance of the irradiated portion was 80.2%.

Moreover, the surface shape of the irradiated area was confirmed by WYKO, and the result was not obvious. Step difference or unevenness, excellent surface uniformity. Further, the inside of the polarizing film was observed by visual observation, and as a result, cracking such as cracking was not confirmed.

[Example 3]

A decolorizing section was formed in the same manner as in Example 1 except that the laser light was irradiated with irradiation conditions of a pulse energy of 71 μJ, a scanning speed of 100 mm/sec, and a pulse repetition rate of 12,480 Hz.

Successfully only decolorizes the area illuminated by the laser light. The transmittance of the unirradiated portion was 44.0%, and the transmittance of the irradiated portion was 92.0%.

Moreover, the surface shape of the irradiation region was confirmed by WYKO, and as a result, there was no significant step or unevenness, and the surface uniformity was excellent. Further, the inside of the polarizing film was observed by visual observation, and as a result, cracking such as cracking was not confirmed.

[Example 4]

Using a semiconductor laser (wavelength: 940 nm) with a continuous wave energy of 30 W, a scanning speed of 10 mm/sec, and a spot diameter of 2 mm A decolorizing section was formed in the same manner as in Example 1 except that the laser beam was irradiated with the irradiation conditions.

The area irradiated with the laser light was slightly decolored, the transmittance of the unirradiated portion was 44.0%, and the transmittance of the irradiated portion was 49.2%.

When the internal observation was carried out, the crack of the crack was not confirmed, and the surface shape of the irradiation region was confirmed. As a result, the unevenness (thickness change) which was perceived by the touch of the finger was observed, and the surface uniformity was poor.

(Comparative Example 1)

One portion of the polarizing film of the paste-attached paste is cut by press working with a dicing blade.

Cracks having a length of 1 mm or more are produced in the peripheral portion of the cut.

(Comparative Example 2)

Polarizing the above paste by pressure processing using a heated engraving knives One part of the film is cut.

Cracks were not confirmed in the peripheral portion where the cutting was performed, but a step caused by thermal deformation occurred, and surface uniformity could not be obtained.

(Comparative Example 3)

The laser beam was irradiated with a carbon dioxide (CO ₂ ) gas laser (wavelength: 10.6 μm) at a pulse energy of 0.8 mJ, a scanning speed of 300 mm/sec, and a pulse repetition rate of 3000 Hz, and the same as in the first embodiment. The method attempts to form a discoloration section.

The area irradiated by the laser light was not decolored, and the transmittance of the unirradiated portion (44.0%) was the same as the transmittance of the irradiated portion.

Further, by confirming the surface shape of the irradiation region, the unevenness (thickness change) which can be perceived by touching with a finger is generated, and the surface uniformity cannot be obtained. Furthermore, internal observation was carried out, and as a result, cracks such as cracks were not confirmed.

[Industrial availability]

The polarizing element of the present invention can be preferably used in a camera-attached image display device (liquid crystal display device, organic EL device) such as a mobile phone such as a smart phone or a notebook PC or a tablet PC.

1‧‧‧Polarized elements

2‧‧‧Decolorization Department

Claims (11)

A polarizing element which is composed of a resin film containing a dichroic substance and has a partially discolored decolorizing portion. The polarizing element of claim 1, wherein a transmittance of the decolorizing section is 46% or more. The polarizing element of claim 1, wherein the decolorizing section is formed by irradiating laser light including light having a wavelength of at least 1500 nm or less. The polarizing element of claim 1, wherein the decolorizing section corresponds to a camera hole portion of the mounted image display device. The polarizing element of claim 1, wherein the dichroic substance is iodine. The polarizing element of claim 1 has a thickness of 30 μm or less. A method of producing a polarizing element, comprising the step of irradiating a resin film containing a dichroic substance with laser light to form a decolorizing portion. The manufacturing method of claim 7, wherein the laser light comprises light having a wavelength of at least 1500 nm or less. The method of manufacturing of claim 7, wherein the laser is a solid laser. An image display device comprising the polarizing element of claim 1. A method of manufacturing an image display device according to claim 10, comprising the steps of laminating a resin film containing a dichroic material on a surface side. The decolorizing portion is formed by, for example, the display panel illuminating the laser light.