KR100955471B1 - Brightness enhancement film - Google Patents

Abstract

PURPOSE: A brightness enhancement film is provided to improve a brightness enhancement effect by including a birefringent sea island fiber in the structure of the film. CONSTITUTION: A brightness enhancement film comprises a base member and a birefringent sea island fiber. The birefringent sea island fiber is a polycarbonate alloy. An island part of the birefringent sea island fiber is a poly ethylene naphthalate(PEN). The see part of the birefringent sea island fiber is formed with a polycarbonate and degenerated glycol polycyclohexylenedimethylene terephthalate(PCTG). The birefringent sea island fiber is formed inside the base member.

Description

{BRIGHTNESS ENHANCEMENT FILM}

The present invention relates to a brightness enhancement film, and more particularly, to a brightness enhancement film in which brightness is remarkably improved while remarkably lowering a production cost by including a chart paper having a specific component of birefringence in a base material.

In the information display technology, the display device has a unique position of cathode ray tube (CRT) for more than half a century. However, in a rapidly developing information age, various display technologies are required. Among them, flat panel displays are expected to become a technology that surpasses CRT in the near future. Already, not only small measuring instruments but also portable computers have become popular, and conventional CRT systems have been replaced by flat panel displays, ranging from monitors to televisions.

  Flat panel display technology is mainly composed of liquid crystal display (LCD), projection display, and plasma display (PDP), which have already secured a market in the TV field. In addition, field emission display (FED) and electroluminescence display (ELD) And it is expected to occupy the field according to each characteristic. LC displays are currently used in notebooks, personal computer monitors, liquid crystal TVs, automobiles, aircrafts, and they account for 80% of the flat panel market. Since late 1998, LCD demand has surged worldwide, have.

Conventional LC displays place liquid crystals and electrode matrices between a pair of absorbing optical films. In an LC display, the liquid crystal portion has an optical state that changes accordingly by moving the liquid crystal portion by an electric field generated by applying a voltage to the two electrodes. This process displays an image by using a polarized light in a specific direction as a 'pixel' containing information. For this reason, the LC display includes a front optical film and a rear optical film that induce polarization.

  In such a liquid crystal display device of the LC display, the utilization efficiency of the light emitted from the backlight is not necessarily high. This is because 50% or more of the light emitted from the backlight is absorbed by the back side optical film. Therefore, in order to increase the utilization efficiency of the backlight in the liquid crystal display, a brightness enhancement film is provided between the optical cavity and the liquid crystal assembly.

  1 is a diagram showing the optical principle of a conventional brightness enhancement film.

  Specifically, the P polarized light from the optical cavity toward the liquid crystal assembly is transmitted through the brightness enhancement film to the liquid crystal assembly. The S polarized light is reflected from the brightness enhancement film into the optical cavity, Direction is reflected in a randomized state and then transmitted to the brightness enhancement film. Finally, S-polarized light is converted into P-polarized light that can pass through the polarizer of the liquid crystal assembly, passes through the brightness enhancement film, and is transmitted to the liquid crystal assembly.

The selective reflection of the S polarized light and the transmission of the P polarized light to the incident light of the brightness enhancement film are performed in a state in which a flat optical layer having anisotropic refractive index and a flat optical layer having an isotropic refractive index are alternately laminated in multiple layers The refractive index difference between the respective optical layers of the optical layers, the optical thickness setting of the optical layers according to the stretching process of the stacked optical layers, and the change of the refractive index of the optical layer.

  That is, the light incident on the brightness enhancement film repeats reflection of S polarized light and transmission of P polarized light while passing through each optical layer, and finally, only P polarized light of incident polarized light is transmitted to the liquid crystal assembly. On the other hand, as described above, the reflected S polarized light is reflected in a randomized polarization state at the diffusive reflection surface of the optical cavity and then transmitted to the brightness enhancement film. As a result, it is possible to reduce the waste of power with loss of light generated from the light source.

However, such a conventional brightness enhancement film has an optical thickness between optical layers, which can be optimized for selective reflection and transmission of incident polarized light by alternately laminating a planar isotropic optical layer and an anisotropic optical layer having different refractive indices, There is a problem that the manufacturing process of the brightness enhancement film is complicated. In particular, since each optical layer of the brightness enhancement film has a flat plate structure, it is necessary to separate the P polarized light and the S polarized light corresponding to a wide incident angle range of the incident polarized light, so that the number of laminated layers of the optical layer excessively increases and the production cost exponentially There was an increasing problem. Further, there is a problem that optical performance is deteriorated due to optical loss due to the structure in which the number of layers of the optical layer is excessively formed. Accordingly, when the birefringent fiber is disposed in the base material, the light incident from the light source is reflected , scattered, and refracted at the birefringent interface, which is the interface between the birefringent fiber and the isotropic substrate , thereby generating light modulation to improve the brightness. However, when general birefringent fibers are used, they are not manufactured in a laminate structure, which is advantageous in that the production cost is low and the production is easy. However, since the effect of the luminance enhancement is insignificant, there is a problem that it is difficult to apply to the industrial field in place of the laminate type brightness enhancement film.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the conventional art, and a first object of the present invention is to provide a brightness enhancement film designed to dramatically improve brightness.

A second object of the present invention is to provide a liquid crystal display device including a brightness enhancement film of the present invention, the brightness of which is remarkably improved.

In order to achieve the first object of the present invention,

(PEN), and the dissolution component is selected from the group consisting of copolyethylene naphthalate (co-PEN), polycarbonate (PC) and polycarbonate alloy. A brightness enhancement film containing at least one birefringent sea chart is produced.

According to another preferred embodiment of the present invention, the substrate may be isotropic.

According to another preferred embodiment of the present invention, the dissolution part may be made of polycarbonate alloy, polycarbonate and modified glycol polycyclohexylenedimethylene terephthalate (PCTG), more preferably poly The carbonate alloy may comprise a polycarbonate and a modified glycol polycyclohexylenedimethylene terephthalate (PCTG) in a weight ratio of 15: 85: 85: 15, most preferably a polycarbonate and a modified glycol polycyclohexane Silane dimethylene terephthalate (PCTG) in a weight ratio of 4: 6 to 6: 4.

According to another preferred embodiment of the present invention, the portion of the birefringent sea chart is anisotropic and the dissected portion may be isotropic.

According to another preferred embodiment of the present invention, the refractive index of the base material and the birefringent chart can be equal to or less than 0.03 in the refractive indexes in the two axial directions, and the difference in the refractive indexes in the remaining one axial direction may be equal to or greater than 0.2.

According to another preferred embodiment of the present invention, when the refractive index in the x-axis direction is nX1, the refractive index in the y-axis direction is nY1, and the refractive index in the z-axis direction is nZ1 and the refractive indices of the birefringent chart are nX2, nY2 and nZ2 , At least one of the X, Y, and Z-axis refractive indices of the base material and the birefringent sea chart may match, and more preferably, the refractive index of the birefringent chart sheet may be nX2> nY2 = nZ2.

According to another preferred embodiment of the present invention, the refractive index of the portion of the dissection segment of the birefringent graphite sheet is such that the difference in refractive index between the two axial directions is 0.03 or less and the difference between the refractive indexes in the other axial direction is 0.2 or more .

According to another preferred embodiment of the present invention, the refractive index in the x-axis direction is nX3, the refractive index in the y-axis direction is nY3, and the refractive index in the z-axis direction is nZ3 in the length direction of the portion of the birefringent chart mark. when the refractive index in the x-axis direction is nX4, the refractive index in the y-axis direction is nY4, and the refractive index in the z-axis direction is nZ4, at least one of the X-, Y- and Z- the absolute value of the difference in refractive index between nX3 and nX4 may be 0.2 or more.

According to another preferred embodiment of the present invention, the refractive index of the dissected portion of the sea chart yarn and the refractive index of the base material may coincide with each other.

According to another preferred embodiment of the present invention, the area ratio of the dissection subdivision portion may be 2: 8: 8: 2 based on the cross-section of the birefringent chart.

According to another preferred embodiment of the present invention, the brightness enhancement film may have a structured surface.

According to another preferred embodiment of the present invention, the birefringent graphite cloth

More preferably the fabric may be woven using the birefringent chart paper as at least one of weft and warp yarns and most preferably one of the weft yarn and the warp yarn is of the isometric type and the other is isotropic Fiber.

According to another preferred embodiment of the present invention, the weft yarn or warp yarn may be formed by gathering 1 to 200 strands of the chart yarn.

In order to achieve the second object,

The liquid crystal display device may further include a reflection unit that reflects the modulated light from the brightness enhancement film back to the brightness enhancement film.

According to another preferred embodiment of the present invention, the brightness enhancement film of the present invention can be included in a flat panel display.

The terms used herein are briefly described.

Unless otherwise noted, 'fiber has birefringence' means that light that is incident on the polymer is refracted into two different directions of light if the fiber is irradiated with light of a different refractive index depending on the direction.

'Isotropic' means that the refractive index is constant regardless of direction when light passes through the object.

'Anisotropy' means that the optical properties of an object are different according to the direction of light, and anisotropic objects have birefringence and correspond to isotropy.

'Light modulation' means that the irradiated light reflects, refracts, scatters, changes the intensity of the light, the period of the wave or the nature of the light.

Unlike the conventional laminate type brightness enhancement film, the brightness enhancement film of the present invention is excellent in brightness enhancement effect without forming a large number of layers including a birefringent graphite sheet inside the substrate. In addition, since hundreds of layers are not laminated on one film, the production is very easy and the production cost is excellent. Further, since the brightness enhancement film of the present invention is remarkably increased in comparison with the technique of inserting the birefringent fiber into the conventional base material, the birefringent interface is remarkably increased so that the brightness enhancement effect is remarkably improved, have. In addition, the birefringent sea lattice composed of the specific components of the present invention has the highest luminance enhancement efficiency as compared with the ordinary birefringent sea lion.

Hereinafter, the present invention will be described in more detail.

Light incident from a light source is reflected , scattered, and refracted at a birefringent interface that is an interface between the birefringent isotope isotropic base material to generate light modulation, thereby remarkably improving the brightness. Specifically, The light emitted from the external light source can be largely divided into S polarized light and P polarized light. If only a specific polarized light is desired, the P polarized light passes through the brightness enhancement film without being influenced by the birefringent interface, whereas the S polarized light passes through the birefringent interface Reflection, scattering, reflection When modulated with randomly shaped wavelengths, that is, S-polarized or P-polarized light, and reflected therefrom, the P-polarized light passes through the brightness enhancement film and the S-polarized light is scattered or reflected again. If this process is repeated, desired P polarized light can be obtained. As described above, when the birefringent fiber is inserted into the substrate instead of the conventional laminate type brightness enhancement film, the production cost is low and the production is easy. However, since the effect of increasing the brightness is insufficient, There has been a problem that it is difficult to apply to an industrial field in place of the above.

The above-mentioned problems are overcome by using birefringent chart paper as the birefringent fiber having the birefringent interface. Specifically, it was confirmed that the effect of light modulation efficiency and luminance improvement was remarkably improved in the case of using birefringent sea chart paper than in the case of using ordinary birefringent fiber. The middle portion of the sea chart has anisotropy, and the anatomy of the chart portion is isotropic. In this case, not only the interface between the core and the substrate, but also the interface between a plurality of the islands constituting the interior of the sea chart and the dissolution part have a birefringent interface, so that a birefringence interface is generated only at the interface between the base and the birefringent fiber The light modulating effect is remarkably increased compared with the fiber, so that it can be applied to a practical industrial field by replacing the laminated type brightness enhancement film. Therefore, the use of birefringent chart paper is superior to the conventional birefringent fiber in that the efficiency of brightness enhancement is excellent, and the birefringent chart has birefringent properties in the interior of the chart, The brightness enhancement efficiency can be remarkably improved as compared with the case where the interface can be formed.

In addition, the birefringent artificial chart used in the present invention was selected as a material having the best light modulation effect and each of them was used as an isotope fraction and a dissection fraction, thereby maximizing the efficiency of luminance enhancement compared to ordinary chart isotherm.

Further, in the case of producing composite fibers by twisting several sea hair strands or tens of strands, for example, when 10 composite sea fibers are twisted to produce one composite fiber, the composite fibers have 100 birefringent interfaces, Modulation may occur. Furthermore, when preparing sea charts made up of multiple strands, for example, producing 10 charts of sea charts, there are 100 birefringent interfaces in the composite fibers and at least 100 light modulation can occur. Such sea art of the present invention can be produced by a co-extrusion method or the like, but is not limited thereto.

As a result, in order to produce microfiber yarn, a conventional sea chart yarn is to utilize the remaining portion of the sea bed microfine by eluting the anatomic matter irrespective of the birefringence or not. In the present invention, In the present invention, it is assumed that the chart portion is made anisotropic and the dissected portion is made isotropic, but in the opposite case, the object of the present invention can be achieved .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the accompanying drawings.

2 is a schematic view of a cross-section of the brightness enhancement film of the present invention. Specifically, in the brightness enhancement film, the birefringent graph paper 31 is freely arranged in the base material 30 having isotropy. Substrate 30, which may be used here, includes thermoplastic and thermosetting polymers that transmit light over a desired range of wavelengths. Preferably, the suitable substrate 30 may be amorphous or semicrystalline and may include a homopolymer, a copolymer, or a blend thereof, and may have a birefringent interface at the interface with the birefringent graphite sheet 31 having optical isotropy, Do. Specifically, polycarbonate (PC); Syndiotactic and isotactic poly (styrene) (PS); Alkyl styrene; Alkyl, aromatic and aliphatic ring containing (meth) acrylates including poly (methyl methacrylate) (PMMA) and PMMA copolymers; Ethoxylated and propoxylated (meth) acrylates; Polyfunctional (meth) acrylates; Acrylated epoxy; Epoxy; And other ethylenically unsaturated materials; Cyclic olefin and cyclic olefin copolymers; Acrylonitrile butadiene styrene (ABS); Styrene acrylonitrile copolymer (SAN); Epoxy; Poly (vinylcyclohexane); PMMA / poly (vinyl fluoride) blends; Poly (phenylene oxide) alloys; Styrene block copolymers; Polyimide; Polysulfone; Poly (vinyl chloride); Poly (dimethylsiloxane) (PDMS); Polyurethane; Unsaturated polyester; Polyethylene; Poly (propylene) (PP); Poly (alkane terephthalate) such as poly (ethylene terephthalate) (PET); Poly (alkanaphthalates) such as poly (ethylene naphthalate) (PEN); Polyamide; Ionomers; Vinyl acetate / polyethylene copolymer; Cellulose acetate; Cellulose acetate butyrate; Fluoropolymers; Poly (styrene) -poly (ethylene) copolymers; PET and PEN copolymers including polyolefin PET and PEN; And poly (carbonate) / aliphatic PET blends. More preferably, it is more preferable to use polyethylene terephthalate (PET), polycarbonate (PC), polycarbonate (PC) alloy, polystyrene (PS), heat resistant polystyrene (PEN), polyethylene naphthalate copolymer (PS), polymethyl methacrylate (PMMA), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), polyurethane (PI), polyvinyl chloride (PVC), styrene acrylonitrile blend (SAN), ethylene vinyl acetate (EVA), polyamide (PA), polyacetal (POM), phenol, epoxy (EP) (UF.MF), unsaturated polyesters (UP), silicon (SI), elastomers, cycloolefin polymers (COP, Japan ZEON, JSR) may be used alone or in combination. More preferably, The same component as that of the dissected portion of the first electrode 31 may be used. Further, the substrate may contain additives such as an antioxidant, a light stabilizer, a heat stabilizer, a lubricant, a dispersant, an ultraviolet absorber, a white pigment, and a fluorescent whitening agent, so long as the above physical properties are not impaired.

Next, the birefringent graphite sheet 31 contained in the base material 30 will be described. Generally, the birefringent graphite sheet 210 can be used without limitations as long as it can be used as a material of a yarn with different optical properties of the graphite powder and the dissolution powder. Therefore, polycarbonate (PC), which is the same material as the substrate; Syndiotactic and isotactic poly (styrene) (PS); Alkyl styrene; Alkyl, aromatic and aliphatic ring containing (meth) acrylates including poly (methyl methacrylate) (PMMA) and PMMA copolymers; Ethoxylated and propoxylated (meth) acrylates; Polyfunctional (meth) acrylates; Acrylated epoxy; Epoxy; And other ethylenically unsaturated materials; Cyclic olefin and cyclic olefin copolymers; Acrylonitrile butadiene styrene (ABS); Styrene acrylonitrile copolymer (SAN); Epoxy; Poly (vinylcyclohexane); PMMA / poly (vinyl fluoride) blends; Poly (phenylene oxide) alloys; Styrene block copolymers; Polyimide; Polysulfone; Poly (vinyl chloride); Poly (dimethylsiloxane) (PDMS); Polyurethane; Unsaturated polyester; Polyethylene; Poly (propylene) (PP); Poly (alkane terephthalate) such as poly (ethylene terephthalate) (PET); Poly (alkanaphthalates) such as poly (ethylene naphthalate) (PEN); Polyamide; Ionomers; Vinyl acetate / polyethylene copolymer; Cellulose acetate; Cellulose acetate butyrate; Fluoropolymers; Poly (styrene) -poly (ethylene) copolymers; PET and PEN copolymers including polyolefin PET and PEN; And poly (carbonate) / aliphatic PET blends. More preferably, it is more preferable to use polyethylene terephthalate (PET), polycarbonate (PC), polycarbonate (PC) alloy, polystyrene (PS), heat resistant polystyrene (PEN), polyethylene naphthalate copolymer (PS), polymethyl methacrylate (PMMA), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), polyurethane (PI), polyvinyl chloride (PVC), styrene acrylonitrile blend (SAN), ethylene vinyl acetate (EVA), polyamide (PA), polyacetal (POM), phenol, epoxy (EP) (UF.MF), unsaturated polyesters (UP), silicon (SI), elastomers, and cycloolefin polymers may be used alone or in combination. However, when polyethylene naphthalate (PEN) is used as a porcelain as the birefringent sea chart 31 of the present invention, and copolyethylene naphthalate and polycarbonate alloy are used singly or as a dissolution component, , The luminance was dramatically improved as compared with the third - order birefringent chart. In particular, when a polycarbonate alloy is used as the dissolution component, a birefringent sea chart having the best optical modulation properties can be produced. In this case, the polycarbonate alloy may preferably be composed of a polycarbonate and a modified glycol polycyclohexylene dimethylene terephthalate (PCTG), more preferably a polycarbonate and a modified glycol poly (PCTG) in the weight ratio of 15: 85: 85: 15 is effective for improving the luminance. If the content of the polycarbonate is less than 15%, the viscosity of the polymer required for securing the radioactivity increases, so that the conventional radiator can not be used. If the content exceeds 85%, the glass transition temperature becomes high, There is a difficult problem.

Most preferably, the polycarbonate and the modified glycol polycyclohexylenedimethylene terephthalate (PCTG) in the weight ratio of 4: 6 to 6: 4 exhibit the most excellent effect for enhancing the luminance (see Table 1).

On the other hand, a method of changing an isotropic material to birefringent is commonly known. For example, in the case of stretching under an appropriate temperature condition, the polymer molecules are oriented and the material becomes birefringent.

In order to maximize the light modulation efficiency of the birefringent sea chart according to an embodiment of the present invention, the optical characteristics of the chart and the dissection may be different, more preferably, the chart is anisotropic and the dissection may be isotropic have. Specifically, the magnitude of the substantial agreement or inconsistency of the refractive index along the X, Y, and Z axes in space on a chart including an optically isotropic anatomical portion and an anisotropic portion is affected by the degree of scattering of the polarized light along its axis . Generally, the scattering ability changes in proportion to the square of the refractive index mismatch. Thus, the greater the degree of discrepancy in refractive index along a particular axis, the more scattered light rays are polarized along that axis. Conversely, when the inconsistency along a particular axis is small, the polarized light rays along the axis are scattered to a lesser degree. If the refractive index of the anatomical portion along an axis substantially coincides with the refractive index of the portion, the incident light polarized by the electric field parallel to this axis is not scattered regardless of the size, shape and density of the sea chart portion, Will pass. Also, when the refractive index along the axis is substantially coincident, the light rays pass through the object without being substantially scattered. More specifically, Fig. 3 is a cross-sectional view showing the path of light transmitted through the birefringent chart of the present invention. In this case, the P wave (solid line) is transmitted without being affected by the birefringent interface at the interface between the external and birefringent charts and between the internal part of the birefringent chart and the dissected part, while the S wave (dotted line) Light modulation is effected by the influence of the birefringent interface at the interface between the chart sea surface and / or the inner part of the birefringent chart.

The light modulation phenomenon at the birefringence interface described above occurs mainly at the interface between the base and the birefringent chart sheet and at the interface between the chart and the anatomy within the birefringent chart. Specifically, when the optical properties of the substrate are isotropic, light modulation occurs at the interface between the base material and the birefringent chart sheet in the same manner as ordinary birefringent fibers. Specifically, the refractive index of the base material and the birefringent chart can be 0.03 or less in refractive index with respect to the two axial directions, and the difference in refractive index with respect to the remaining one axial direction may be 0.2 or more. More specifically, when the refractive index in the x-axis direction is nX1, the refractive index in the y-axis direction is nY1, the refractive index in the z-axis direction is nZ1, and the refractive indexes of the birefringent chart are nX2, nY2 and nZ2, At least one of the X, Y, and Z-axis refractive indexes of the sea chart may match, and the refractive index of the birefringent chart may be nX2 > nY2 = nZ2.

In the present invention, it is advantageous that the optical quality of the birefringent chart is different from that of the dissected portion to produce a birefringence interface. More specifically, the refractive index may be set such that the difference in refractive index with respect to two axial directions is 0.03 or less and the refractive index with respect to the other axial directions is 0.03 or less, It is preferable that the difference in refractive index with respect to one axial direction is 0.2 or more. In this case, the P wave passes through the birefringent interface of the solar cell, but the S wave can cause optical modulation. More specifically, the refractive index in the x-axis direction, the refractive index in the y-axis direction, and the refractive index in the z-axis direction, which are the lengthwise direction of the birefringent chart sheet, are denoted by nY3 and nZ3, When the nX4, the refractive index in the y axis direction is nY4, and the refractive index in the z axis direction is nZ4, at least one of the X, Y, and Z axis refractive indexes of the base material and the birefringent sea chart may match, The absolute value of the difference may be 0.05 or more. Most preferably, the difference in refractive index with respect to the longitudinal direction of the dissected segment of the sea chart yarn is not less than 0.2, and when the dissection portion with respect to the remaining two axial directions and the refractive index of the portion are substantially matched, the light modulation efficiency can be maximized have. On the other hand, when the refractive indices of the base material and the dissected portions in the birefringent chart are coincident, it is advantageous to increase the light modulation efficiency.

Regarding the shape of the birefringent chart sheet of the present invention, the cross section of the chart sheet may have any shape according to the purpose, and it may have a deformed cross section having various shapes such as a circle, an ellipse, and a polygon. Likewise, the cross section of the middle portion of the chart of the present invention can be a circular, oval or polygonal cross-section.

4A-4I are cross-sectional views of birefringent light modulating fibers according to an embodiment of the invention. As can be seen from FIGS. 4a to 4i, the shape, size, number, and arrangement of portions of the light guide in the present invention can be efficiently adjusted according to the purpose of light modulation. 4A is a cross-sectional view of a normal chart paper An approximately circular portion 420a is partitioned through the dissection portion 410a. FIG. 4B shows a large area of the dissected portion 410b, and FIG. 4C shows an oval shape of the sea chart. In FIG. 4D, the portion 420d is elliptical and its arrangement is zigzag. In addition, although the cross section of the sea chart has a rectangular structure, it can have both a polygonal structure and a cross-sectional structure.

 As illustrated in FIGS. 4E and 4F, the shadow portion may be located at the center of the chart sheet, or the dissected portion may not be at the center of the chart sheet.

In some embodiments, the portion of the figure need not all be the same size. For example, as illustrated in Figs. 4G and 4H, chart charts may include different cross-sectional-size chart portions 420g and 421g. In this particular embodiment, one of the diagonal portions 420g is relatively larger in cross-section than the other diagonal portion 421g. The portion of the figure may correspond to two or more different sized groups, and in fact all of the sizes may be different. Furthermore, it is also possible to add the birefringent and / or isotropic sheath 430i to the portion 420i as shown in FIG. 3I.

Preferably, the figure portions are arranged in the chart, and the area ratio of the anatomy portion is preferably 2: 8: 8: 2. The monofilament fineness of the sea chart yarn is preferably 0.5 to 30 denier, and it is preferable that the above-mentioned sea chart yarn is arranged in the range of 500 to 4,000,000 / cm3. In addition, the refractive index of the dissolution portion may be coincident with the refractive index of the base material of the brightness enhancement film.

On the other hand, the birefringent chart can be placed in the form of a yarn in the base material or arranged in the form of a fabric. First, when the birefringent charts are arranged in the form of a yarn in the base material, preferably a plurality of the birefringent charts can be arranged in one direction and more preferably, the chart can be arranged in the base material perpendicular to the light source In this case, the light modulation efficiency is maximized. On the other hand, the line charts arranged in a line may be dispersed and arranged as needed, or they may be in contact with or dropped from each other between sea charts, or they may be arranged in a densely packed form if they are in contact with each other.

For example, when three or more types of charts are arranged in a circle whose cross section is circular, triangles obtained by connecting the centers of three circles tangent to each other on a cross section perpendicular to the major axis direction of the charts are triangles . Further, in the cross section perpendicular to the major axis direction of the chart sheet (cylindrical), the first-tier circle and the second-tier circle are in contact with each other, the second-tier circle and the third-tier circle are in contact with each other, However, it is sufficient to satisfy the condition that "at least two other charts contacting each other on the side of the cylinder are in contact with each other on the side of the cylinder" for each chart. In this range, for example, the first-tier circle and the second-tier circle are brought into contact with each other, the second-tier circle and the third-tier circle are separated through the supporting medium, and the third- It is also possible to take a configuration.

It is preferable that at least two sides of the triangle connecting the centers of the three circles directly tangent to each other in the cross section perpendicular to the major axis direction of sea chart have a length substantially equal to each other. desirable. It is preferable that the layered state of the sea chart in the thickness direction of the brightness enhancement film is laminated so that a plurality of layers are sequentially in contact with each other and that a chart sheet made of a cylindrical body having a substantially equal diameter is packed closely desirable.

Therefore, in this more preferred form, the plurality of chart marks are cylindrical bodies each having a circle diameter in a cross section perpendicular to the major axis direction, and chart charts located on the inner side of the outermost surface layer in the cross section have six It is in contact with the side of the cylindrical double-refracted body and the cylinder.

On the other hand, the birefringent chart can be arranged in the form of a fabric in the base material (see Figs. 5A and 5B). In this case, it is preferable that the fabric of the present invention includes the weft and / or the warp yarn as the birefringent chart sheet, and most preferably the weft yarn or the warp yarn of the present invention is used as the weft yarn, Do. Preferably, the weft yarns or the warp yarns may have 1 to 200 strands of the birefringent chart yarns.

The volume of the birefringent sea bream of the present invention is preferably 1% to 90% with respect to 1 cm 3 of the brightness enhancement film. If the ratio is less than 1%, the brightness enhancement effect is insignificant. If the ratio exceeds 90%, the amount of scattering due to the birefringence interface increases and light loss may occur.

Further, the number of the birefringent artificial satellites may be 500 to 4,000,000 within 1 cm 3 of the brightness enhancement film. The cross-sectional diameter of a portion of the intralesional chart of the birefringent chart may also have a significant influence on the light modulation. When the diameter of the cross section of each birefringent chart portion is smaller than the optical wavelength, the effect of refraction, scattering, and reflection is reduced, and light modulation hardly occurs. When the cross-sectional diameter of the portion is too large, the light is specularly reflected from the surface of the sea chart sheet and diffusion in the other direction is very small. The cross-sectional diameter of the aligned portion may vary depending on the intended use of the optics. For example, the diameter of the fibers can vary depending on the wavelength of electromagnetic radiation important for a particular application, and different fiber diameters are required to reflect, scatter, or transmit visible, ultraviolet, infrared and microwave radiation.

The brightness enhancement film of the present invention may preferably comprise a structured surface layer according to the purpose. 6A to 6F are cross-sectional views of the structured surface of the brightness enhancement film of the present invention, in which the incident surface and the exit surface of the brightness enhancement film may be flat with respect to the light irradiated from the light source 600a in FIG. 6A, The birefringent chart sheet 621b positioned on (adjacent to) the light source 600b is closely arranged, and the birefringent chart sheet 620b located farther from the light source 600b is disposed sparsely .

The structured surface layer may be formed on a surface from which light is emitted. The structured surface layer may be in a prism shape, a lenticular shape, or a convex lens shape. Specifically, in FIG. 6C, the surface on which the light is emitted on the brightness enhancement film may have a curved surface 630c having a convex lens shape. The curved surface 630c may be focused or defocused on the light transmitted through the surface. 6D, the prism pattern 630d may be formed on the light exit surface. In this case, the birefringent grid 620d may not be formed on the structured surface layer 630d as shown in FIG. 6D, It is possible that the birefringent grid pattern 620e is formed on the surface layer 630e or the birefringent grid pattern 620f is formed only on the structured surface layer 630f as shown in Fig.

The rear surface layer of the brightness enhancement film may be provided with an unevenness by matting to impart scratch resistance, provided that it does not adversely affect the effect of the present invention.

 On the other hand, light transmitted through a light source can be natural light or polarized light, and various materials exhibiting birefringence as a birefringent chart can be used. However, from the standpoint of alignment, cross-sectional stability and durability, .

Next, a method for producing the birefringent chart of the present invention will be described. The birefringent artificial marble of the present invention can be applied without limitation of any kind as long as it can produce ordinary charts such as a complex spinning process. The spinneret and the spinning nozzle to be used may be any shape as long as they can produce birefringent graphite sheet. However, the spinneret and the spinneret are designed so as to substantially coincide with the arrangement of the sections on the cross- Can be used. Specifically, a hollow pin or a ductile component extruded from a spinneret or the like designed appropriately so as to divide the fraction into the spinneret is joined with a harmonic component (flow) supplied from a flow path designed to fill the gap therebetween, The sheet can be formed by extruding it from the discharge port while being gradually thinned, and any spinneret can be used as long as the chart sheet includes two or more radiation centers. An example of the spinneret which is preferably used is shown in Figs. 7 and 8. However, the spinneret which can be used in the method of the present invention is not limited thereto.

Specifically, Figure 7 is an example of a preferred spinneret that may be applied to the present invention. Specifically, in the spinneret 700, the polymer (molten material) for the inside of the distributed charged polymer storage portion 701 is distributed to the polymer introduction path 702 for forming a bundle formed by a plurality of hollow pins, The molten marine polymer (molten material) is introduced into the polymer electrolyte storage portion 704 for distribution by means of the sea-splitting polymer introduction passage 703. The hollow pin forming the molten polymer introducing path 702 penetrates the seaweed polymer reservoir 704 and flows into the center portion of each of the plurality of channel-like multi-channel composite channels 705 formed therebelow And is opened downward. The polymeric polymers are introduced into the center portion of the core-sheath type composite fluid passage 705 from the lower end of the isotropic distribution polymer introduction path 702, and the polymeric solution for decomposing in the polymeric solution storage portion 704 is introduced into the channel- (705) to form a core-sheath type composite stream in which the star-shaped polymer is used as the core and the marine polymer is used as the core, wherein the core portion is formed by centering two or more radial centers The shim parts are arranged in a group. After the plurality of core-sheath type composite streams are introduced into the funnel-shaped merging channel 706, the plurality of core-sheath type complex streams are joined to each other in the merging channel 706 to form a sea- do. The sea-island composite flow gradually decreases in cross-sectional area in the horizontal direction while flowing through the funnel-shaped confluent passage 706, and is discharged from the discharge port 707 at the lower end of the confluent passage 706.

8 shows an example of another preferred spinneret 810 according to the present invention. The spinneret polymer storage 811 and the sea component polymer storage 812 are composed of an introduction passage 813 for a polymer component polymer, The molten polymer in the molten polymer storage portion 811 is distributed into the plurality of molten polymer introduction passages 813 and introduced into the molten polymer storage portion 812 through the molten polymer storage portion 811 . While the seawater polymer is accommodated in the seawater polymer storage 812 via a seawater polymeric furnace 815. On the other hand, the branched polymer introduced into the seawater polymer storage portion 812 passes through the seawater polymer (molten material) accommodated in the seawater polymer storage portion 812 and flows into the core-sheath type mixed-fluid passage 814 After flowing, it flows down from its center. On the other hand, the seawater polymer in the seawater polymer storage portion 812 flows down around the core-sheath type composite flow passage 814 so as to surround the periphery of the center portion of the isobutene polymer. As a result, a plurality of core-sheath type complex flows are formed in the plurality of core-sheath type composite flow passages 814, and flows into the funnel-shaped confluent passage 816. As a result, Flows down while decreasing the cross sectional area in the horizontal direction, and is discharged through the discharge port 817 to finally produce the birefringent chart of the present invention.

As a result, the birefringent artificial satellite of the present invention can form a birefringent interface in the interior of the fiber, unlike ordinary birefringent fibers, so that the efficiency of light modulation is high, so that it is possible to produce a product in an actual industrial environment. Further, when the material of the island portion and the sea portion is limited, the light modulation efficiency can be superior to that of the ordinary sea chart.

Further, in the case of producing composite fibers by twisting several sea hair strands or tens of strands, for example, when 10 composite sea fibers are twisted to produce one composite fiber, the composite fibers have 100 birefringent interfaces, Modulation can occur. Furthermore, when preparing sea charts made up of multiple strands, for example, producing 10 charts of sea charts, there are 100 birefringent interfaces in the composite fibers and at least 100 light modulation can occur. Such sea art of the present invention can be produced by a co-extrusion method or the like, but is not limited thereto.

Therefore, in order to produce the microfine yarn, the conventional sea chart yarn is to utilize the remaining portion as a microfine yarn by dissolving the anatomical component irrespective of the birefringence or not. In the present invention, In the present invention, it is assumed that the chart portion is made anisotropic and the dissected portion is made isotropic, but in the opposite case, the object of the present invention can be achieved .

According to another embodiment of the present invention, there is provided a liquid crystal display device including the brightness enhancement film of the present invention. Specifically, FIG. 9 shows an example of a liquid crystal display device employing the brightness enhancement film of the present invention, in which a reflection plate 920 is inserted on a frame 910, a cold cathode fluorescent lamp 930 is mounted on an upper surface of the reflection plate 920, . An optical film 940 is disposed on the upper surface of the cold cathode fluorescent lamp 930 and the optical film 940 includes a diffusion plate 941, a light diffusion film 942, a prism film 943, 944 and an absorbing polarizing film 945 are stacked in this order, but the order of lamination may be varied depending on the purpose, or some of the constituent elements may be omitted or a plurality of them may be provided. For example, the diffusion plate 941, the light diffusion film 942, the prism film 943, and the like may be omitted from the overall configuration and may be changed in order or formed at different positions. Further, a phase difference film (not shown) or the like can also be inserted at an appropriate position in the liquid crystal display device. On the other hand, the liquid crystal display panel 960 may be positioned on the upper surface of the optical film 940 by being inserted into the mold frame 950.

The light emitted from the backlight 930 reaches the diffuser plate 941 of the optical film 240. The light transmitted through the diffusion plate 941 passes through the light diffusion film 942 in order to advance the traveling direction of the light perpendicularly to the optical film 940. After passing through the light diffusion film 942, the light passes through the prism film 943, reaches the light modulation film 944, and light modulation occurs. Specifically, the P wave transmits the light-modulated film 944 without loss, but the S wave causes optical modulation (reflection, scattering, refraction, etc.) and is reflected again by the reflection plate 920, which is the back surface of the cold cathode fluorescent lamp 930 And the properties of the light are randomly changed into a P wave or an S wave, and then pass through the optical modulation film 944 again. And then reaches the liquid crystal display panel 960 after passing through the absorption polarizing film 945. [ As a result, when the brightness enhancement film of the present invention is inserted into a liquid crystal display device due to the above-described principle, a remarkable increase in brightness can be expected as compared with a conventional brightness enhancement film.

In the present invention, the use of the brightness enhancement film has been described mainly with respect to a liquid crystal display, but the present invention is not limited thereto, and can be widely used in flat panel display technologies such as projection displays, plasma displays, field emission displays and electroluminescent displays.

Hereinafter, the present invention will be described in detail with reference to Examples and Experimental Examples. The following Examples and Experimental Examples are merely illustrative of the present invention, and the scope of the present invention is not limited to the following Examples and Experimental Examples.

≪ Example 1 >

An isotropic PC (nx = 1.57, ny = 1.57, nz = 1.57) mixed with a 5: 5 mixture of polycarbonate and modified glycol polycyclohexylenedimethylene terephthalate (PCTG) 1.88, ny = 1.57, and nz = 1.57), and 200 parts of the above-mentioned portions were arranged. With this composition, spinning was carried out under the conditions of spinning temperature of 305 ° C. and spinning speed of 1500 M / min with unstretched shrub 150/24, and then a 50/24 birefringent marine starch was produced through 3 times stretching . Twenty four strands of the sea chart were prepared and weighed with isotropic polyethylene terephthalate fibers. The fabric woven thereafter is placed between a 2PC alloy sheet (having the same components and optical properties as those of the birefringent sea-island seawater), and a pressure is applied under a constant tension so that the fabric woven into the interior of the Pc- Lt; / RTI > Thereafter, a mixed UV-cured coating resin of an epoxy acrylate and a urethane acrylate having a refractive index of 1.54 was applied to a point where the fiber was laminated to the laminated PC and to the point where it was introduced into the mirror-surface roll, Thereby producing a fused sheet in the form of a laminated sheet. The coating resin exhibits a refractive index of 1.54 before UV coating curing but a refractive index of 1.57 after curing. Thus, a brightness enhancement film having a thickness of 400 m was prepared.

≪ Example 2 >

The same procedure as in Example 1 was carried out except that polycarbonate and modified glycol polycyclohexylenedimethylene terephthalate (PCTG) were mixed in a ratio of 3: 7 and isotropic PC was used as the material of the birefringent chart sheet and base material To prepare a brightness enhancement film.

≪ Example 3 >

The procedure was carried out in the same manner as in Example 1 except that polycarbonate and modified glycol polycyclohexylenedimethylene terephthalate (PCTG) were mixed in a ratio of 7: 3 and isotropic PC was used as the material of the birefringent chart sheet and the base material To prepare a brightness enhancement film.

<Example 4>

A brightness enhancement film was produced in the same manner as in Example 1, except that isotropic CO-PEN (nx = 1.57, ny = 1.57, nz = 1.57)

 &Lt; Example 5 >

A brightness enhancement film was produced in the same manner as in Example 1 except that the dissolution component and the substrate were made of polycarbonate.

&Lt; Example 6 >

A dissolution test was conducted in the same manner as in Example 1 except that the dissolution component and the substrate were composed of an isotropic PC array in which polycarbonate and modified glycol polycyclohexylenedimethylene terephthalate (PCTG) were mixed at a ratio of 1: 9 Respectively.

&Lt; Example 7 >

Reinforced film was produced in the same manner as in Example 1, except that the dissolution component and the substrate were composed of an isotropic PC array in which polycarbonate and denatured glycol polycyclohexylenedimethylene terephthalate (PCTG) were mixed at a ratio of 9: 1 Respectively.

&Lt; Comparative Example 1 &

The procedure of Example 1 was repeated except that the isotonic particulate was isotropic PET (nx = ny = nz = 1.57) and the dissolution component was isotropic C0-PEN (nx = ny = nz = 1.57) 400 [micro] m.

&Lt; Comparative Example 2 &

A PEN resin of IV 0.53 was polymerized in place of the birefringent chart paper of Example 1 to prepare a yarn of unstretched yarn 150/24. The spinning temperature was 305 ° C and the spinning speed was 1500 M / min. The obtained undrawn filament yarn was stretched 3 times at a temperature of 150 ° C to produce a 50/24 filament yarn. The stretched PEN fibers exhibit birefringence, and the refractive indices in each direction are nx = 1.88, ny = 1.57, and nz = 1.57. A brightness enhanced film having a thickness of 400 탆 was prepared in the same manner as in Example 1 except that the sea-island fiber of Example 1 was replaced with the above birefringent PEN fiber.

&Lt; Comparative Example 3 &

A brightness enhancement film was produced in the same manner as in Example 1, except that a birefringent sea chart was used in which the fractions were acid diatopic polystyrene (nx = 1.57, ny = 1.61, nz = 1.61).

&Lt; Comparative Example 4 &

A brightness enhancement film was produced in the same manner as in Example 1, except that the fraction was anisotropic PET (nx = 1.69, ny = 1.54, nz = 1.54).

<Experimental Example>

The following properties were evaluated for the brightness enhancement films prepared in Examples 1 to 7 and Comparative Examples 1 to 4, and the results are shown in Table 1.

1. Brightness

The brightness of the prepared brightness enhancement film was measured in the following manner. The panels were assembled on a diffusion plate, two diffusion sheets and a 32 "direct-type backlight unit equipped with a brightness enhancement film, and the brightness was measured at nine points using a BM-7 meter of Topcon Co., and the average value was shown.

2. Transmission

The transmittance was measured by the ASTM D1003 method using a COH300A analyzer of NIPPON DENSHOKU, Japan.

3. Polarization degree

The degree of polarization was measured using a RETS-100 analyzer from OTSKA.

4. Water Absorption Rate

According to ASTM D570, after immersing in water at 23 DEG C for 24 hours, the change in weight% of the sample before and after the treatment was measured.

5. Sheet

       A brightness enhancement film was assembled into a 32-inch backlight unit and allowed to stand in a thermo-hygrostat at 60 ° C and 75% for 96 hours. The brightness of the brightness enhancement film was visually observed.

        Good: Fair: Fair: Fair: Bad: Bad

6. UV resistance

       The output of a 130 mW ultraviolet lamp (365 nm) was irradiated for 10 minutes at a height of 10 cm using SMDT51H manufactured by Nippon Tatex Corporation. The YI (Yellow Index) before and after treatment was measured using an SD-5000 analyzer of NIPPON DENSHOKU The yellowing degree was evaluated.

[Table 1]

Brightness (cd / m 2) Transmittance (%) Polarization degree (%) Absorption Rate (%) Shemum UV resistance Example 1 400 52 78 0.24 O 2.3 Example 2 380 52 75 0.24 O 2.0 Example 3 380 52 75 0.24 O 2.0 Example 4 375 53 74 0.24 O 2.5 Example 5 350 55 70 0.24 O 2.0 Example 6 360 50 72 0.24 O 2.0 Example 7 360 50 72 0.24 O 2.0 Comparative Example 1 270 85 2 0.24 O 1.5 Comparative Example 2 320 55 50 0.24 O 1.8 Comparative Example 3 305 79 25 0.24 O 2.0 Comparative Example 4 310 78 30 0.24 O 2.0

As can be seen from Table 1, the overall optical properties of the brightness enhancement films (Examples 1 to 7) including the birefringent sea chart of the present invention were superior to those of Comparative Examples 1 to 4, which did not use the same. Especially, the effect of improving the luminance was shown in comparison with the case where the shading portion was used as another anisotropic material (Comparative Examples 3 and 4). On the other hand, when the material of the dissected portion of the sea chart and the material of the base material satisfy the ratio of 15: 85: 85: 15 of the polycarbonate and the modified glycol polycyclohexylenedimethylene terephthalate (PCTG), the effect of strengthening the brightness (Examples 4 to 7)

Since the brightness enhancement film of the present invention is excellent in optical modulation performance, it can be widely used in optical devices such as cameras and liquid crystal display devices and flat panel displays requiring high brightness such as mobile phones and LCDs.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the appended claims. .

1 is a schematic view illustrating the principle of a conventional brightness enhancement film.

2 is a schematic view of a cross section of a cut surface of a brightness enhancement film according to an embodiment of the present invention.

3 is a cross-sectional view showing the path of light incident on the birefringent chart of the present invention.

4A-4I are cross-sectional views of birefringent charts according to an embodiment of the present invention.

5a-5b are top views of a fabric woven with birefringent charts according to one embodiment of the present invention.

6A to 6F are cross-sectional views of a structured surface of a brightness enhancement film of the present invention.

7 is a cross-sectional view of a spinneret for producing birefringent chart paper according to an embodiment of the present invention.

8 is a cross-sectional view of a spinneret for producing birefringent chart paper according to another embodiment of the present invention.

9 is an exploded perspective view of a liquid crystal display device including the brightness enhancement film of the present invention.

Claims (22)

materials; And And a birefringent sea chart which is a polycarbonate alloy composed of polycarbonate and modified glycol polycyclohexylenedimethylene terephthalate (PCTG) as a dissolution component in polyethylene naphthalate (PEN) And a birefringence interface is formed at a boundary between the portion and the dissolution portion. The brightness enhancement film according to claim 1, wherein the substrate is isotropic. delete The brightness enhancement film of claim 1, wherein the polycarbonate alloy comprises a polycarbonate and a modified glycol polycyclohexylenedimethylene terephthalate (PCTG) in a weight ratio of 15: 85: 85: 15. . The method of claim 1, wherein the polycarbonate alloy comprises a polycarbonate and a modified glycol polycyclohexylenedimethylene terephthalate (PCTG) in a weight ratio of 4: 6 to 6: 4. . The brightness-enhancement film according to claim 1, wherein the part of the birefringent graphite sheet is anisotropic and the dissolution part is isotropic. 2. The optical sheet according to claim 1, wherein the refractive indices of the base material and the birefringent graphite sheet are 0.03 or less in refractive index with respect to two axial directions, and the difference in refractive index with respect to the remaining one axial direction is 0.2 or more. . The optical sheet according to claim 1, wherein when the refractive index in the x-axis direction is nX1, the refractive index in the y-axis direction is nY1, the refractive index in the z-axis direction is nZ1 and the refractive indexes of the birefringent chart are nX2, nY2 and nZ2, Wherein at least one of X, Y, and Z refractive indexes of the birefringent sea chart coincides with each other. The brightness enhancement film according to claim 8, wherein the refractive index of the birefringent chart sheet is nX2 > nY2 = nZ2. 2. The method according to claim 1, wherein the refractive index of the dissected segment of the birefringent graphite sheet is such that the difference in refractive index between the two axial directions is 0.03 or less and the difference in refractive index with respect to the remaining one axial direction is 0.2 or more Reinforced film. 11. The method according to claim 10, wherein the refractive index in the x-axis direction is nX3, the refractive index in the y-axis direction is nY3, and the refractive index in the z-axis direction is nZ3 in the longitudinal direction of the portion of the birefringent graphite sheet, Wherein at least one of the X-axis, Y-axis, and Z-axis refractive indices of the substrate and the birefringent sea chart coincides with each other when the nX4, the y-axis refractive index is nY4, and the z-axis refractive index is nZ4. 12. The brightness enhancement film according to claim 11, wherein an absolute value of a difference in refractive index between nX3 and nX4 is 0.2 or more. The brightness intensifying film according to claim 1, wherein the refractive index of the dissected portion of the sea chart yarn coincides with the refractive index of the substrate. 2. The brightness enhancement film according to claim 1, wherein the area ratio of the dissection subdivision portion with respect to the cross-section of the birefringent graphite sheet is 2: 8: 8: 2. The brightness enhancement film of claim 1, wherein the brightness enhancement film has a structured surface. The brightness enhancement film according to claim 1, wherein the birefringent artificial satellite is a fabric. 17. The brightness enhancement film of claim 16, wherein the fabric is woven using the birefringent chart paper as at least one of weft and warp. 18. The brightness enhancement film according to claim 17, wherein any one of the weft yarn and the warp yarn is in the sea chart and the other is an isotropic fiber. [17] The brightness enhancement film of claim 17, wherein the weft yarn or warp yarn is formed by gathering 1 ~ 200 strands of the chart yarn. A liquid crystal display comprising the brightness enhancement film according to any one of claims 1, 2 and 4 to 19. The liquid crystal display of claim 20, wherein the liquid crystal display further comprises reflection means for reflecting light modulated in the brightness enhancement film back to the brightness enhancement film. A flat panel display comprising the brightness enhancement film of any one of claims 1, 2, and 4 to 19.

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