KR20180105611A - Optical Film And Liquid Crystal Display Comprising The Same - Google Patents

Abstract

An optical film according to the present invention includes a polarizing plate, a diffusion sheet, and a prism sheet. The diffusion sheet is bonded to the lower surface of the polarizing plate, and a first diffusion member and a second diffusion member are bonded to the diffusion sheet. The prism sheet is bonded to the lower surface of the diffusion sheet. Accordingly, the present invention can refract and diffuse incident light in an interface between the diffusion members and the adhesive layers.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical film and a liquid crystal display (LCD)

The present invention relates to a liquid crystal display device having an optical film incorporated therein, and more particularly to a liquid crystal display device having a structure in which an optical film for light uniformity and light gathering provided in a backlight unit is laminated on a lower polarizer plate.

BACKGROUND ART [0002] Liquid crystal display devices are becoming increasingly widespread due to features such as light weight, thinness, and low power consumption driving. The liquid crystal display device is used as a portable computer such as a notebook PC, an office automation device, an audio / video device, and an indoor / outdoor advertisement display device. A transmissive liquid crystal display device that occupies most of the liquid crystal display device controls an electric field applied to the liquid crystal layer to modulate light incident from the backlight unit to display an image.

The backlight unit is roughly divided into a direct type and an edge type. The direct-type backlight unit has a structure in which a plurality of light sources are disposed under the liquid crystal display panel. The edge type backlight unit has a structure in which a light source is disposed so as to face the side face of the light guide plate and a plurality of optical films are disposed between the liquid crystal display panel and the light guide plate. In the edge type backlight unit, the light source irradiates light to one side of the light guide plate, and the light guide plate converts the linear light source or point light source into a planar light source. The edge type backlight unit can be realized with a thinner thickness than the direct type backlight unit.

Hereinafter, a liquid crystal display device provided with an edge-type backlight unit according to the related art will be described with reference to Figs. 1 and 2. Fig. 1 is an exploded perspective view showing the structure of a liquid crystal display device provided with an edge-type backlight unit according to the related art. Fig. 2 is a cross-sectional view showing the structure of a liquid crystal display device having an edge-type backlight unit according to the prior art, cut in a cutting line I-I 'in Fig.

1 and 2, a liquid crystal display device according to the present invention includes a liquid crystal display panel (LCP) and an edge type backlight unit (EBLU) disposed below the liquid crystal display panel (LCP). The liquid crystal display panel LCP has a liquid crystal layer LC formed between the upper glass substrate SU and the lower glass substrate SL and can be realized in any liquid crystal mode.

The edge type backlight unit EBLU includes a light source LS, a light guide plate LG and an optical film OPT so that light emitted from the light source LS is transmitted through the light guide plate LG and the optical films OPT Converted into a uniform surface light source and provided to the liquid crystal display panel (LCP). The light guide plate LG may further include a reflection plate REF for returning the light leaked through the lower surface of the light guide plate LG to the light guide plate LG.

A cover bottom (CB) is disposed below the reflector (REF). It is preferable that the cover bottom CB has a bowl shape for accommodating the edge type backlight units EBLU therein. In addition, the cover bottom CB includes a material having a high thermal conductivity and high rigidity so that heat from the light source LS can be reliably discharged to the outside. As an example, the cover bottom CB may be made of aluminum, aluminum nitride (AlN), electrogalvanized steel sheet (EGI), stainless steel (SUS), galvalume (SGLC), aluminum plated steel (aka ALCOSTA), tinned steel And the like. Further, such a metal plate may be coated with a high conductivity material for promoting heat transfer.

A guide panel GP and a top case TC are disposed at the edges of the liquid crystal display panel LCP. The guide panel GP is a rectangular mold frame in which glass fiber is mixed in a synthetic resin such as polycarbonate or the like to cover the upper and side surfaces of the liquid crystal display panel LCP and surrounds the side surface of the edge type backlight unit EBLU. The guide panel GP supports the liquid crystal display panel LCP and maintains a constant gap between the liquid crystal display panel LCP and the optical film OPT. The top case TC is made of a metal material such as a galvanized steel plate and has a structure to cover the upper and side surfaces of the guide panel GP and is provided with at least one of a guide panel GP and a cover bottom CB, .

It is preferable that the light source LS uses a light emitting device having a high luminance at a low electric power such as an LED. The light source LS supplies light to the light guide plate LG. In the edge-type backlight unit EBLU, the light source LS is positioned on the side surface of the liquid crystal display panel LCP. That is, the light source LS supplies light to the side surface of the light guide plate LG corresponding to at least one side surface of the light guide plate LG.

The light guide plate LG has a panel-like rectangular parallelepiped shape having a surface corresponding to the area of the liquid crystal display panel LCP. The upper surface of the light guide plate LG is opposed to the liquid crystal display panel LCP. Light is diffused and distributed internally from the light source LS installed on the side surface of the light guide plate LG so as to be evenly distributed in the light guide plate LG and light is guided to the upper surface on which the liquid crystal display panel LCP is disposed .

Light guided to the liquid crystal display panel (LCP) by the light guide plate (LG) is not suitable for use as a backlight. For example, it may be a state in which the luminance distribution does not have an even distribution over the entire area of the liquid crystal display panel (LCP). Alternatively, the surface of the liquid crystal display panel LCP may not be condensed in the direction of the main observer. Therefore, in order to fully utilize it as a backlight, it is necessary to condense and diffuse light.

For this function, an optical film OPT is disposed between the light guide plate LG and the liquid crystal display panel LCP. Hereinafter, with reference to Figs. 3 to 4, the structure of the optical films OPT according to the prior art will be described. 3 is a cross-sectional view showing the structure of optical films having a diffusion film in a liquid crystal display device according to the prior art.

Optical films (OPT) disposed under the liquid crystal display panel (LCP) shown in FIG. 3 represent a laminated structure of optical films (OPT) generally used. For example, the lower prism sheet PRL, the upper prism sheet PRU, and the diffusion sheet DIF may be sequentially stacked.

On the upper surface of the lower prism sheet PRL, prismatic prism patterns are arranged in parallel. Particularly, the convex horns and the concave horns are alternately arranged, and the sharp horns are arranged in parallel in the first direction. The upper prism sheet PRU may have the same prism pattern as the lower prism sheet PRL. However, it is preferable that the upper portion of the upper prism sheet PRU is arranged in parallel in a second direction orthogonal to the first direction. The light emitted from the light guide plate LG passes through the lower prism sheet PRL and the upper prism sheet PRU and is condensed in the form of a Gaussian distribution around the normal to the surface of the liquid crystal display panel LCP.

The diffusion sheet DIF functions to disperse the light having passed through the prism sheets PRL and PRU to have a uniform luminance distribution over the entire surface of the liquid crystal display panel LCP. For example, in the case of an edge type backlight, the side on which the light source is located may have brighter luminance than the opposite side. Further, in the case of the direct-type backlight, the portion where the light source is located may have brighter luminance than the peripheral portion of the light source. The diffusion sheet DIF uniformly diffuses the luminance distribution of the non-uniform light with respect to the entire surface of the liquid crystal display panel (LCP). For diffusion function, the diffusion sheet (DIF) may have beads (BD) dispersed on its upper surface.

Although the prism sheets PRL and PRU and the diffusion sheet DIF are made to be suitable for use as a backlight, there is a possibility that the luminance itself may decrease while passing through the optical films. This causes a decrease in the energy efficiency required to generate the backlight. Particularly, the luminance reduction due to the diffusion sheet DIF is extremely severe. To solve this problem, a high brightness diffusion film (DBEF) has been proposed. 4 is a cross-sectional view showing a structure of a conventional liquid crystal display device having a high-luminance diffusion film.

The high brightness diffusion film (DBEF) solves the problem that the high brightness layer and the low refractive layer are laminated, and the brightness lost again by reflecting the light lost by reflection back to the upper surface. Referring to FIG. 4, the structure is the same as that shown in FIG. (DBEF) is disposed instead of the diffusion film (DIF).

Thus, the optical films according to the related art have a structure in which they are sequentially stacked between the liquid crystal display panel (LCP) and the light guide plate (LG). That is, the upper prism sheet PRU is placed in a lay-down state on the lower prism sheet PRL. Therefore, a predetermined air layer exists between the upper prism sheet PRU and the lower prism sheet PRL. Since the refractive index of the air layer is different from that of the prism sheets PRL and PRU, the light passing through the air layer can be diffused.

Similarly, a diffusion film (DIF) or a high-brightness diffusion film (DBEF) is also placed on the upper prism sheet PRU in a lay-down state. Therefore, an air layer is also present between the upper prism sheet PRU and the diffusion film DIF or between the upper prism sheet PRU and the high brightness diffusion film DBEF. It is possible to obtain an effect of diffusing light while passing through these air layers.

However, due to the structure in which the optical films (OPT) are simply laminated, the thickness becomes thick, which hinders thinning of the liquid crystal display device. However, in the case of merely laminating, the air layer is eliminated, so that the diffusion effect by the air layer can not be obtained, and the luminance distribution becomes uneven. Moire, Rainbow Mura, or hot-spot patterns may also occur. Such luminance unevenness, pattern generation, light leakage, and the like are evaluated to be not suitable for use as a backlight, so that the liquid crystal display device can not be made ultra thin.

The present invention is designed to solve the problems of the prior art, and provides an ultra-thin liquid crystal display device having an optical film integrally.

It is another object of the present invention to provide a liquid crystal display device capable of preventing deflection of a liquid crystal display panel by matching shrinkage forces between optical films attached to the upper and lower surfaces of the liquid crystal display device.

Still another object of the present invention is to provide an ultra thin liquid crystal display device in which an optical film is integrated by laminating a lower polarizer plate, a support sheet and a prism sheet.

In order to achieve the above object, an optical film according to the present invention includes a polarizing plate, a diffusion sheet, and a prism sheet. The diffusion sheet adheres to the lower surface of the polarizing plate, and the first diffusion member and the second diffusion member are bonded. The prism sheet is bonded to the lower surface of the diffusion sheet.

In one example, the diffusion sheet includes an adhesive layer positioned between the first diffusion member and the second diffusion member, and the first diffusion member and the second diffusion member are bonded by the adhesive layer.

In one example, the first diffusion member and the second diffusion member are spaced from each other.

In one example, the distance between the first diffusion member and the second diffusion member is 0.1 to 20 占 퐉.

In one example, the first diffusion member and the second diffusion member include a plurality of beads.

In one example, the first diffusion member and the second diffusion member each include a rugged surface due to a plurality of beads, and the rugged faces of the first diffusion member and the second diffusion member face each other.

In one example, the first diffusion member and the second diffusion member have a refractive index of 1.5 to 1.7.

In one example, the adhesive layer has a refractive index of 1.4 to 1.6.

For example, the refractive indexes of the first diffusion member and the second diffusion member are different from the refractive index of the adhesive layer.

For example, the second diffusion member further includes a third diffusion member adhered to the bottom surface.

Further, the liquid crystal display device according to the present invention includes a display panel and an optical film. The optical film is adhered to the lower surface of the display panel. The optical film includes a polarizing plate, a diffusion sheet, and a prism sheet. The diffusion sheet adheres to the lower surface of the polarizing plate, and the first diffusion member and the second diffusion member are bonded. The prism sheet is bonded to the lower surface of the diffusion sheet.

The optical film according to the present invention can be manufactured by forming an adhesive layer having a refractive index different from that of the diffusing members between the diffusing members including a plurality of beads to produce a diffusing sheet so that light incident from below is refracted at the interface between the diffusing members and the adhesive layers There is an advantage that it can spread.

Further, the liquid crystal display device according to the present invention has the advantage of preventing moire phenomenon from occurring by securing the haze of the diffusion sheet including the above-mentioned diffusion sheet.

In addition, since the lower polarizer, the diffusion sheet, and the prism sheet are integrally attached to the lower part of the liquid crystal display panel by bonding the separate optical films and the thickness of the backlight unit can be reduced, the liquid crystal display can be made as thin as possible There is an advantage to be able to.

1 is an exploded perspective view showing a structure of a liquid crystal display device provided with an edge-type backlight unit according to the related art.
2 is a cross-sectional view showing the structure of a liquid crystal display device having an edge-type backlight unit according to a related art cut in a cutting line I-I 'in FIG.
3 is a cross-sectional view showing the structure of an optical film having a diffusion film in a liquid crystal display device according to the related art.
4 is a cross-sectional view showing the structure of optical films having a DBEF film in a conventional liquid crystal display device.
5 is a cross-sectional view showing the structure of a liquid crystal display device according to the first embodiment of the present invention.
6 is a cross-sectional view showing a part of a region of a liquid crystal display device according to the first embodiment of the present invention.
7 is a cross-sectional view showing the diffusion sheet of the present invention.
8 to 13 are cross-sectional views illustrating a manufacturing process of an optical film according to a first embodiment of the present invention.
14 is a cross-sectional view illustrating a liquid crystal display device according to a second embodiment of the present invention.
15 is a sectional view showing a liquid crystal display device according to Comparative Example 1. Fig.
16 is a sectional view showing a liquid crystal display device according to Comparative Example 2. Fig.
17 is a cross-sectional view illustrating a liquid crystal display device according to an embodiment of the present invention.
18 is a white image of the liquid crystal display device according to Comparative Example 1. Fig.
19 is a white image of a liquid crystal display device according to Comparative Example 2. Fig.
20 is a white image of a liquid crystal display device according to an embodiment of the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals throughout the specification denote substantially identical components. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

≪ Embodiment 1 >

5 is a cross-sectional view showing a structure of a liquid crystal display device according to a first embodiment of the present invention. 6 is a cross-sectional view showing a partial area of a liquid crystal display device according to the first embodiment of the present invention. 7 is a cross-sectional view showing the diffusion sheet of the present invention.

Referring to FIG. 5, a liquid crystal display (LCD) according to the first embodiment of the present invention includes a liquid crystal display panel (LCP), an upper polarizing plate (UPOL), and an optical film (OPT).

The liquid crystal display panel (LCP) includes an upper substrate and a lower substrate bonded together by a liquid crystal layer interposed therebetween. An upper polarizer UPOL is attached to the upper surface of the liquid crystal display panel LCP. A lower polarizing plate (LPOL) is attached to the lower surface of the liquid crystal display panel (LCP). The upper polarizer UPOL has a light transmission axis or light blocking axis aligned in the first direction. The lower polarizing plate LPOL has a light transmission axis or light blocking axis aligned in the second direction. When the liquid crystal display (LCD) is normally black, it is preferable that the first light transmission axis and the second light transmission axis are arranged to be orthogonal to each other. On the other hand, in the case of normally white, the first light transmission axis and the second light transmission axis may be arranged in parallel.

The optical film OPT includes a lower polarizing plate (LPOL), a diffusion sheet (DIF), and a prism sheet (PS).

The lower polarizing plate (LPOL) includes a core layer (PVA) and an upper protective layer (UPL). The core layer (PVA) serves to polarize light, and may be made of, for example, polyvinyl alcohol (PVA) or the like. The core layer (PVA) may be a stretched PVA formed by a stretching method or a coated PVA formed by a coating method. The core layer (PVA) is liable to be deformed by the moisture contained in the air. Accordingly, the protective layer is disposed on at least one side of the core layer (PVA). In the present invention, the upper protective layer (UPL) is adhered to the upper surface of the core layer (PVA). The upper protective layer UPL may be triacetylcellulose (TAC), acrylic, polyethylene terephthalate (PET), polycarbonate (PC), polyethylene naphthalate (PEN), or the like. The upper protective layer UPL may be bonded to the core layer PVA through the first UV layer UR1 and any adhesive may be used if the first UV layer UR1 is a transparent adhesive.

In the present invention, the structure of the lower polarizing plate (LPOL) including the upper protective layer UPL bonded to the upper portion of the core layer (PVA) and the upper protective layer (UPL) And may further include a lower protective layer, and is not particularly limited as long as the protective layer is disposed on at least one surface.

The diffusion sheet DIF serves to disperse the light passing through the prism sheet PS so as to have a uniform luminance distribution over the entire surface of the liquid crystal display panel LCP. For example, in the case of an edge type backlight, the side on which the light source is located may have brighter luminance than the opposite side. Further, in the case of the direct-type backlight, the portion where the light source is located may have brighter luminance than the peripheral portion of the light source. The diffusion sheet DIF uniformly diffuses the luminance distribution of the non-uniform light with respect to the entire surface of the liquid crystal display panel (LCP).

More specifically, the diffusion sheet DIF is integrally formed by bonding the first diffusion member PET1 and the second diffusion member PET2 through the first adhesive layer PSA1. The first diffusion member PET1 and the second diffusion member PET2 each include a plurality of beads BD.

The first diffusion member PET1 and the second diffusion member PET2 transmit light incident from the light source and support a plurality of beads BD. For this purpose, the first diffusion member PET1 and the second diffusion member PET2 are made of a material capable of transmitting light incident from a light source and having high resistance to moisture in the air, for example, polyethylene terephthalate (PET) But is not limited to, any one selected from the group consisting of polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), and polyepoxy (PE). The first diffusion member PET1 and the second diffusion member PET2 may be formed to have a thin thickness, for example, a thickness of 10 mu m to 250 mu m in response to the thinning of the backlight unit. By making the first diffusion member PET1 and the second diffusion member PET2 each have a thickness of 10 mu m or more, the backlight unit can be made as thin as possible as long as the mechanical properties and heat resistance of the optical film are not deteriorated. Further, by making each of the first diffusion member PET1 and the second diffusion member PET2 have a thickness of 250 mu m or less, the backlight unit can be made thinner and the mechanical properties and heat resistance of the optical film can be maximized.

Each of the first diffusion member PET1 and the second diffusion member PET2 includes a plurality of beads BD dispersed therein. The plurality of beads BD can be manufactured using the same or different resins as the materials of the first diffusion member PET1 and the second diffusion member PET2 and the first diffusion members PET1 and PET2, 2 < / RTI > diffuser < RTI ID = 0.0 > (PET2). ≪ / RTI > The size of the bead BD may be appropriately selected according to the thickness of each of the first diffusion member PET1 and the second diffusion member PET2, and may be 1 to 10 mu m. The sizes of the beads BD may be substantially the same and the distribution in the first diffusion member PET1 and the second diffusion member PET2 may be regular. Alternatively, the sizes of the beads BD are different from each other, and the distribution in the first diffusion member PET1 and the second diffusion member PET2 may be irregular.

A first adhesive layer PSA1 for bonding the first diffusion member PET1 and the second diffusion member PET2 therebetween is located. The first adhesive layer PSA1 can be used as any adhesive that can bond the first diffusion member PET1 and the second diffusion member PET2 and has good elasticity and adhesion properties and can prevent the occurrence of fine bubbles and prevent peeling. Do. For example, the first adhesive layer PSA1 may be a pressure sensitive adhesive (PSA), a UV adhesive, an aqueous adhesive, etc. The first adhesive layer PSA1 may have a certain elasticity The first adhesive layer PSA1 may include a plurality of beads and may also serve as a diffusion characteristic.

The diffusion sheet DIF according to the present invention includes a first diffusion member PET1 and a second diffusion member PET2 including a plurality of beads BD for diffusing light to enhance uniformity of light and conceal a lower light source, ) Each exhibit a haze characteristic of 10 to 50%, and the haze of the entire diffusion sheet (DIF) may be 20 to 100%.

In addition, the diffusion sheet (DIF) of the present invention should be capable of diffusing light even if no air layer exists between the lower polarizer (LPOL) and the diffusion sheet (DIF). For this, the first diffusion member PET1 and the second diffusion member PET2 of the diffusion sheet DIF may each have a refractive index of 1.5 to 1.7, and the first diffusion member PET1 and the second diffusion member PET2 ) May have a refractive index of 1.5 to 1.7. The refractive index of the first adhesive layer PSA1 positioned between the first diffusion member PET1 and the second diffusion member PET2 may be 1.4 to 1.6. At this time, the refractive indices of the first diffusion member PET1 and the second diffusion member PET2 may be the same, but the refractive index of the first adhesive layer PSA1 is different from that of the first diffusion member PET1 and the second diffusion member PET2. Lt; / RTI >

Referring to FIG. 6, light incident from the lower portion of the second diffusion member PET2 to the second diffusion member PET2 passes through the second diffusion member PET2. Since the refractive indexes of the second diffusion member PET2 and the first adhesive layer PSA1 are different from each other, light is refracted at the interface between the second diffusion member PET2 and the first adhesive layer PSA1 to change the path. The path of the light may be changed so as to be condensed upward or diffused to the side. The light that has passed through the inside of the first adhesive layer PSA1 is changed to a path that is refracted again at the interface of the first diffusion member PET1 having a different refractive index and is condensed or diffused. Therefore, the diffusion sheet DIF of the present invention is formed by forming the first adhesive layer PSA1 having a different refractive index between the first diffusion member PET1 and the second diffusion member PET2, 2 diffusing member PET2 can be adhered and light can be diffused.

Referring to FIG. 7, the first diffusion member PET1 and the second diffusion member PET2 should be spaced apart from each other so that light incident from the lower portion of the diffusion sheet DIF of the present invention can be diffused. That is, the first diffusion member PET1 and the second diffusion member PET2 are not in contact with each other, but the first adhesive layer PSA1 can be positioned therebetween. As described above, the light incident on the diffusion sheet DIF from the bottom can be refracted and diffused at the interface of the first adhesive layer PSA1 having a refractive index different from that of the first and second diffusion members PET1 and PET2. To this end, the first adhesive layer PSA1 must be present between the first diffusion member PET1 and the second diffusion member PET2. If the first diffusion member PET1 and the second diffusion member PET2 are in contact with each other and the first adhesive layer PSA1 does not exist, the refractive indices of the first diffusion member PET1 and the second diffusion member PET2 The light can not diffuse through the diffusion sheet DIF without changing the path. Accordingly, the diffusion sheet (DIF) of the present invention can have a distance between the first diffusion member (PET1) and the second diffusion member (PET2) of 0.1 to 20 mu m. If the distance between the first diffusion member PET1 and the second diffusion member PET2 is 0.1 m or more, light is refracted at the interface between the first and second diffusion members PET1 and PET2 and the first adhesive layer PSA1 If the distance between the first diffusion member PET1 and the second diffusion member PET2 exceeds 20 mu m, the thickness of the diffusion sheet DIF is too thick to achieve thinning.

The diffusion sheet (DIF) of the present invention described above is adhered to the lower polarizer plate (LPOL) through the second UV layer (UR2).

Referring again to FIG. 5, the prism sheet PS includes a prism portion PP on which a prism pattern is formed on the base sheet SS.

The base sheet SS transmits light incident from the light source and protects the prism section PP of the prism sheet PS. For this purpose, the base sheet SS is made of a material that can transmit light incident from a light source and has high resistance to moisture in the air such as polyethylene terephthalate (PET), polycarbonate (PC), polypropylene (PP) ), Polyethylene (PE), polystyrene (PS), and polyepoxy (PE). However, the present invention is not limited thereto. The base sheet SS may be formed to have a thin thickness, for example, a thickness of 10 to 250 mu m in response to the thinning of the backlight unit. By making the base sheet SS have a thickness of 10 mu m or more, the backlight unit can be made as thin as possible as long as the mechanical properties and heat resistance of the optical film are not deteriorated. In addition, by making the base sheet SS have a thickness of not more than 250 mu m, it is possible to achieve thinning of the backlight unit and to maximize the mechanical properties and heat resistance of the optical film.

The prism portion PP is located on the base sheet SS and can condense the light incident from the light source by a plurality of prism patterns. The prism portion PP includes a first prism pattern P1 having a first height and a second prism pattern P2 having a second height. The first height and the second height are formed differently.

The liquid crystal display of the present invention has a structure in which the prism sheet PS is joined to the diffusion sheet DIF by the third UV layer UR3. Particularly, it is preferable that some of the plurality of prism patterns P1 and P2 of the prism portion PP formed on the prism sheet PS are inserted into the third UV layer UR3. Since the first prism patterns P1 having the first height and the second prism patterns P2 having the second height are alternately arranged, the prism sheet PS has a higher height than the first height and the second height It is preferable that a part of the acid having a height is inserted into the third UV layer UR3. For example, if the first height is higher than the second height, a portion of the first prism patterns P1 having the first height may be inserted into the third UV layer UR3.

Thus, even if a part of the at least one first prism patterns P1 is inserted into the third UV layer UR3, the second prism patterns P2 are spaced a certain distance from the third UV layer UR3 . That is, an air layer may be interposed between the third UV layer UR3 and the second prism patterns P2. When the prism portions of the prism sheet PS are not made of the mountains having different heights, the mountains of all the prism portions PP are inserted into the third UV layer UR3, so that the amount of the air layer is remarkably reduced, do. As a result, the refraction of light is not sufficient, and the brightness may decrease. Accordingly, in the present invention, the first prism patterns P1 and the second prism patterns P2 must have different heights. In the present invention, since the prism patterns P1 and P2 of the prism portion PP of the prism sheet PS have different heights, an air layer can be sufficiently ensured between the third UV layer UR3 The luminance loss can be minimized.

The optical film OPT in which the lower polarizing plate LPOL, the diffusion sheet DIF and the prism sheet PS are laminated can be bonded to the lower surface of the liquid crystal display panel LCP through the second adhesive layer PSA2 have.

As described above, in the liquid crystal display device according to the first embodiment of the present invention, a first adhesive layer having a different refractive index is formed between a first diffusion member including a plurality of beads and a second diffusion member, The first and second diffusion members can be refracted and diffused at the interface of the first adhesive layer.

In addition, since the lower polarizer, the diffusion sheet, and the prism sheet are integrally attached to the lower part of the liquid crystal display panel by bonding the separate optical films and the thickness of the backlight unit can be reduced, the liquid crystal display can be made as thin as possible There is an advantage to be able to.

Hereinafter, a method of manufacturing the optical film according to the first embodiment of the present invention will be described.

8 to 13 are cross-sectional views illustrating a manufacturing process of an optical film according to the first embodiment of the present invention.

Referring to FIG. 8, a first diffusion member PET1 and a second diffusion member PET2 are manufactured by applying a resin mixed with beads BD to two base films and curing the same. At this time, the base film and the resin may use the same material, for example, polyethylene terephthalate. The first diffusion member PET1 and the second diffusion member PET2 may have a refractive index of 1.6 and a haze of 10 to 50%.

Next, referring to FIG. 9, the first adhesive layer PSA1 is applied on the second diffusion member PET2. At this time, the first adhesive layer PSA1 is applied to the rugged surface due to the beads BD of the second diffusion member PET2. Then, the first adhesive layer PSA1 is applied in a thickness of 1 to 20 mu m to secure the adhesive force, and the first diffusion member PET1 and the second diffusion member PET2 are separated from each other. Further, the first adhesive layer PSA1 can be formed of a material having a refractive index of 1.5.

10, on the surface of the second diffusion member PET2 on which the first adhesive layer PSA1 is applied, the rugged surfaces of the first diffusion member PET1 and the first diffusion member PET1 are disposed so as to face each other . The diffusion sheet DIF is manufactured by laminating the first diffusion member PET1 and the second diffusion member PET2 and attaching them together. The diffusion sheet DIF adjusts the haze of the first diffusion member PET1 and the second diffusion member PET2 so as to have a final haze of 20 to 100%.

Referring to FIG. 11, a third UV layer UR3 is coated on one surface of the prepared diffusion sheet DIF, and the prism sheet PS is laminated and cemented. The prism portion PP of the prism sheet PS is inserted into the third UV layer UR3 and adhered to the diffusion sheet DIF.

12, a first UV layer UR1 is applied to the prepared upper protective layer UPL and a second UV layer UR2 is coated on one surface of the prepared diffusion sheet DIF. One surface of the first UV layer UR1 and the core layer PVA of the upper protective layer UPL are disposed opposite to each other and the second UV layer UR2 of the diffusion sheet DIF and the core layer PVA Place it face to face.

Referring to FIG. 13, an integrated optical film (OPT) is manufactured by simultaneously laminating the disposed upper protective layer (UPL), the core layer (PVA), and the diffusion sheet (DIF). The upper protective layer UPL protects the upper portion of the core layer PVA and the diffusion sheet DIF to which the prism sheet PS is attached can protect the lower portion of the core layer PVA. The thus produced optical film is cut to a desired size and attached to the lower surface of the liquid crystal display panel.

≪ Embodiment 2 >

Hereinafter, a liquid crystal display device according to a second embodiment of the present invention will be described with reference to FIG. 14 is a cross-sectional view illustrating a liquid crystal display device according to a second embodiment of the present invention.

Referring to FIG. 14, a liquid crystal display (LCD) according to a second embodiment of the present invention includes a liquid crystal display panel (LCP), an upper polarizing plate (UPOL), and an optical film (OPT). The optical film OPT includes a lower polarizing plate (LPOL), a diffusion sheet (DIF), and a prism sheet (PS).

Unlike the liquid crystal display (LCD) according to the first embodiment described above, it further includes a third diffusion member PET3 adhered to the diffusion sheet DIF by the third adhesive layer PSA3. The configurations of the liquid crystal display panel LCP, the upper polarizer UPOL, the lower polarizer LPOL, and the prism sheet PS are the same as those of the first embodiment described above, and thus the description thereof is omitted.

The diffusion sheet DIF of the present invention is a diffusion sheet DIF in which the first diffusion member PET1 and the second diffusion member PET2 are bonded via the first adhesive layer PSA1 and the second diffusion member PET2 and the third diffusion member PET3 Is bonded via the third adhesive layer PSA3. The first diffusion member PET1, the second diffusion member PET2, and the third diffusion member PET3 each include a plurality of beads BD.

The third diffusion member PET3 transmits light incident from a light source and supports a plurality of beads BD. To this end, the third diffusion member PET3 may be made of the same material as the first diffusion member PET1 and the second diffusion member PET2. For example, the third diffusion member PET3 may be made of a material capable of transmitting light incident from a light source and having high resistance to moisture in the air such as polyethylene terephthalate (PET), polycarbonate (PC), poly But is not limited to, any one selected from the group consisting of propylene (PP), polyethylene (PE), polystyrene (PS), and polyepoxy (PE) Further, the third diffusion member PET3 may be formed to have a thin thickness, for example, a thickness of 10 to 250 mu m in response to the thinning of the backlight unit. By making the third diffusion member PET3 have a thickness of 10 mu m or more, the backlight unit can be made as thin as possible as long as the mechanical properties and heat resistance of the optical film are not deteriorated. Further, by making the third diffusion member PET3 have a thickness of 250 mu m or less, it is possible to achieve thinning of the backlight unit and maximize the mechanical properties and heat resistance of the optical film.

The third diffusion member PET3 includes a plurality of beads BD dispersed therein. The plurality of beads BD may be made of the same or different resin as the material of the third diffusion member PET3 and may be included in the range of 10 to 50 parts by weight with respect to the third diffusion member PET3. The plurality of beads BD of the third diffusion member PET3 may be made of the same material and size as those of the beads of the first diffusion member PET1 and the second diffusion member PET2 .

And a third adhesive layer PSA3 for bonding them between the second diffusion member PET2 and the third diffusion member PET3. The third adhesive layer PSA3 bonds the second diffusion member PET2 and the third diffusion member PET3 and is made of an acrylic copolymer or the like which has good elasticity and adhesion properties and can prevent the occurrence of fine bubbles to prevent peeling. Can be used. In addition, the third adhesive layer PSA3 has a role of not only adhesion, but also has a certain elasticity so as to protect sheets from external impact. In addition, the third adhesive layer PSA3 may include a plurality of beads and may also serve as a diffusion characteristic.

The diffusion sheet DIF according to the present invention includes a first diffusion member PET1 including a plurality of beads BD and a second diffusion member PET2 having a plurality of beads BD in order to enhance uniformity of light by diffusing light, And the third diffusion member PET3 each exhibit a haze characteristic of 10 to 50%, and the haze of the entire diffusion sheet DIF may be 20 to 100%. The diffusing sheet (DIF) of the present invention may have refractive indexes of 1.5 to 1.7 of the first diffusion member (PET1), the second diffusion member (PET2) and the third diffusion member (PET3) The refractive index of the bead BD may also be 1.5 to 1.7. The refractive index of the third adhesive layer PSA3 may be 1.4 to 1.6. At this time, the refractive indices of the first diffusion member PET1, the second diffusion member PET2 and the third diffusion member PET3 may be the same, but the refractive indexes of the first adhesion layer PSA1 and the third adhesion layer PSA3 are The refractive indices of the first diffusion member PET1, the second diffusion member PET2, and the third diffusion member PET3 may be different from each other.

Therefore, the diffusion sheet DIF of the present invention has the first adhesive layer PSA1 and the second adhesive layer PS2 different in refractive index from each other between the first diffusion member PET1, the second diffusion member PET2 and the third diffusion member PET3, By forming the third adhesive layer PSA3, there is an advantage that the first diffusion member PET1, the second diffusion member PET2, and the third diffusion member PET3 can be bonded and light can be diffused.

Also, in the diffusion sheet (DIF) of the present invention, the second diffusion member (PET2) and the third diffusion member (PET3) must be spaced from each other so that light incident thereunder can be diffused. That is, the second diffusion member PET2 and the third diffusion member PET3 are not in contact with each other, but the third adhesive layer PSA3 can be positioned therebetween. As described above, the light incident on the diffusion sheet DIF from the bottom can be refracted and diffused at the interface of the third adhesive layer PSA3 having a different refractive index from the second and third diffusion members PET2 and PET3. To this end, a third adhesive layer PSA3 must be present between the second diffusion member PET2 and the third diffusion member PET3. Therefore, the diffusion sheet (DIF) of the present invention can have a distance of 0.1 to 20 mu m between the second diffusion member (PET2) and the third diffusion member (PET3).

As described above, the liquid crystal display (LCD) according to the second embodiment of the present invention includes a first diffusion member including a plurality of beads, a first diffusion member having a refractive index different from those of the first diffusion member, By forming the adhesive layer and the third adhesive layer, the light incident from below can be transmitted to the interface between the first diffusion member and the first adhesive layer, the interface between the second diffusion member and the first adhesive layer, the interface between the second diffusion member and the third adhesive layer, There is an advantage that it can be refracted and diffused at the interface between the diffusion member and the third adhesive layer.

In addition, since the lower polarizer, the diffusion sheet, and the prism sheet are integrally attached to the lower part of the liquid crystal display panel by bonding the separate optical films and the thickness of the backlight unit can be reduced, the liquid crystal display can be made as thin as possible There is an advantage to be able to.

Hereinafter, experimental data on the optical characteristics of the liquid crystal display according to the comparative example and the embodiments of the present invention will be described. FIG. 15 is a cross-sectional view of a liquid crystal display device according to Comparative Example 1, FIG. 16 is a cross-sectional view illustrating a liquid crystal display device according to Comparative Example 2, and FIG. 17 is a cross-sectional view illustrating a liquid crystal display device according to an embodiment of the present invention. FIG. 18 is a white image of the liquid crystal display device according to Comparative Example 1, FIG. 19 is a white image of the liquid crystal display device according to Comparative Example 2, and FIG. 20 is a white image of the liquid crystal display device according to the embodiment of the present invention.

In the liquid crystal display device according to Comparative Example 1, the upper polarizer plate is positioned on the upper surface of the liquid crystal display panel, and the lower polarizer plate having the upper protective layer and the lower protective layer attached to the lower surface of the liquid crystal display panel with the core layer therebetween. A diffusion sheet and two prism sheets are disposed under the liquid crystal display panel to constitute a liquid crystal display device.

In the liquid crystal display device according to Comparative Example 2, the upper polarizer is positioned on the upper surface of the liquid crystal display panel, and the lower polarizer having the upper protective layer and the lower protective layer attached to the lower surface of the liquid crystal display panel with the core layer therebetween. The diffusion sheet is attached to the lower surface of the lower polarizer plate as an adhesive layer, and the prism sheet is attached to the lower surface of the diffusion sheet. The separate prism sheet is not attached to other sheets but is spaced apart to constitute a liquid crystal display device.

The liquid crystal display according to the embodiment of the present invention is the liquid crystal display according to the first embodiment of the present invention shown in FIG.

Referring to Fig. 18, in the liquid crystal display device of Comparative Example 1, the total thickness of the optical film under the liquid crystal display panel was 930 mu m, and no moire occurred in the white image. Referring to Fig. 19, in the liquid crystal display device of Comparative Example 2, the total thickness of the optical film under the liquid crystal display panel was 935 mu m, and moire occurred in the white image. Referring to Fig. 20, in the liquid crystal display device of the embodiment of the present invention, the total thickness of the optical film under the liquid crystal display panel was 545 mu m, and no moire occurred in the white image.

As a result, the thickness of the liquid crystal display device according to the embodiment of the present invention can be reduced to 385 mu m as compared with Comparative Example 1 in which the diffusion sheet and the prism sheet are spaced apart. Further, in the liquid crystal display device according to the embodiment of the present invention, the thickness of 390 mu m can be reduced without generating moire as compared with Comparative Example 2 in which the diffusion sheet and the prism sheet are bonded.

As described above, according to the optical film of the present invention, the diffusion sheet is manufactured by forming an adhesive layer having a refractive index different from that of the diffusion members between the diffusion members including a plurality of beads, There is an advantage that it can be refracted and diffused at the interface of the adhesive layers.

Further, the liquid crystal display device according to the present invention has the advantage of preventing moire phenomenon from occurring by securing the haze of the diffusion sheet including the above-mentioned diffusion sheet.

In addition, since the lower polarizer, the diffusion sheet, and the prism sheet are integrally attached to the lower part of the liquid crystal display panel by bonding the separate optical films and the thickness of the backlight unit can be reduced, the liquid crystal display can be made as thin as possible There is an advantage to be able to.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

EBLU: Edge type backlight unit LCP: Liquid crystal display panel
LS: Light source: LG: Light guide plate
CB: Cover bottom REF: Reflector
OPT: optical film SU: upper glass substrate
SL: lower glass substrate LC: liquid crystal layer
LPOL: lower polarizer plate UPOL: upper polarizer plate
DIF: diffusion sheet PS: prism sheet

Claims (10)

Polarizer;
A diffusion sheet adhered to a bottom surface of the polarizing plate and having a first diffusion member and a second diffusion member adhered to each other, the diffusion sheet including a plurality of beads and at least one convex portion formed by the beads; And
And a prism sheet bonded to the bottom surface of the diffusion sheet through a UV layer and including first prism patterns and second prism patterns having different heights,
Wherein the first prism patterns are inserted into the UV layer and the second prism patterns are spaced apart from the UV layer,
An air layer is interposed between the UV layer and the second prism patterns,
Wherein at least one convex portion of said first diffusing member and at least one convex portion of said second diffusing member face each other in a 1: 1 correspondence and are spaced apart by a distance of 0.1 to 20 占 퐉. The method according to claim 1,
Wherein the diffusion sheet includes a first adhesive layer positioned between the first diffusion member and the second diffusion member, and the first diffusion member and the second diffusion member are bonded by the first adhesive layer. The method according to claim 1,
Wherein the first diffusion member and the second diffusion member have a refractive index of 1.5 to 1.7. 3. The method of claim 2,
Wherein the first adhesive layer has a refractive index of 1.4 to 1.6. 3. The method of claim 2,
Wherein the refractive indexes of the first diffusion member and the second diffusion member are different from the refractive index of the first adhesive layer. The method according to claim 1,
And a third diffusion member adhered to a lower surface of the second diffusion member. The method according to claim 6,
Wherein the third diffusion member includes a plurality of convex portions and the convex direction of the convex portion is the same as the convex direction of the convex portion of the second diffusion member adjacent to the third diffusion member. 8. The method of claim 7,
Further comprising a second adhesive layer between the second diffusion member and the third diffusion member, wherein the interface between the second adhesive layer and the second diffusion member is flat. The method according to claim 1,
And the first prism pattern directly contacts the bottom surface of the diffusion sheet. Display panel; And
And an optical film adhered to a lower surface of the display panel,
In the optical film,
A polarizer adjacent to a lower surface of the display panel;
A diffusion sheet adhered to a bottom surface of the polarizing plate and adhered to a first diffusion member and a second diffusion member each including at least one convex portion; And
And a prism sheet bonded to the bottom surface of the diffusion sheet through a UV layer and including first prism patterns and second prism patterns having different heights,
Wherein the first prism patterns are inserted into the UV layer and the second prism patterns are spaced apart from the UV layer,
An air layer is interposed between the UV layer and the second prism patterns,
Wherein a convex portion of the first diffusion member and a convex portion of the second diffusion member are opposed to each other with a distance of 0.1 to 20 탆.

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