KR20090040502A - Backlight unit assembly - Google Patents

Abstract

A backlight unit assembly is provided to uniformly diffuse light emitted from a light guide plate to prevent light loss, thereby improving brightness. An optical complex film comprises a transparent material layer, a light diffusion layer and a prism layer. The light diffusion layer is formed in one surface of the transparent material layer. The light diffusion layer comprises binder resin and a light diffusion particle. The prism layer is formed on the light diffusion layer. A bottom layer is formed in the other surface of the transparent material layer. The bottom layer comprises binder resin and particle. A diffusion film is positioned in a lower part of the optical complex film.

Description

Backlight unit assembly

The present invention relates to a backlight unit assembly used in a liquid crystal display (Liquid Crystal Display).

As the industrial society develops into an advanced information age, the importance of the electronic display device as a medium for displaying and transmitting various information is increasing day by day. CRT (Cathode Ray Tube), which has been widely used in the past, has limitations due to large installation space, which makes it difficult to increase the size. Therefore, such as liquid crystal display (LCD), plasma display panel (PDP), field emission display (FED), and organic EL It is being replaced by various flat panel display devices. Among such flat panel display devices, in particular, in the case of liquid crystal display devices (LCDs), due to the advantages of thin, light, and low power consumption as a technology-intensive device in which liquid crystal and semiconductor technologies are combined, its structure and manufacturing technology have been researched and developed. In addition to the areas where liquid crystal displays have been widely used, such as notebook computers, desktop computer monitors, and portable personal communication devices (PDAs and mobile phones), large-scale technology is gradually exceeding its limitations. It is being used as a new display device that can replace CRT, which is synonymous with display, as it is applied to large TV of TV.

In the liquid crystal display (LCD) device, since the liquid crystal itself cannot emit light, a separate light source is installed at the rear of the device to adjust the intensity of the passing light through the liquid crystal installed in each pixel to realize contrast. do. In more detail, the liquid crystal display device is a device for controlling the light transmittance by using the electrical properties of the liquid crystal material, the uniformity and the directionality is controlled by passing through various functional prism films or sheets by emitting light from the light source lamp on the back of the device Indirect light-emitting display device that implements an image by passing light through a color filter to realize red, blue, green (R, G, B) colors, and controlling the contrast of each pixel by an electric method As a light emitting device that provides a light source, it is an important component for determining image quality such as brightness and uniformity of a liquid crystal display device.

A backlight unit (BLU) is widely used as the light emitting device, and a general backlight unit is as shown in FIG. 1. That is, the backlight unit sequentially passes through the light guide plate 3, the diffusion sheet 4, and the prism sheet 5 by using light sources 1 such as a cold cathode fluorescent lamp (CCFL). To reach the liquid crystal panel 6. Here, the light guide plate 3 transmits the light emitted from the light source 1 to be distributed over the front surface of the liquid crystal panel 6 having a flat shape, and the diffusion sheet 4 may obtain uniform light intensity over the entire screen. At the same time, it performs a function of concealing the device such as the light source 1 mounted on the lower portion of the diffusion sheet 4 from the front. On the other hand, the prism sheet 5 performs a light path control function for causing the light rays of various directions passing through the diffusion sheet 4 to be converted into a range of viewing angle θ suitable for the viewer to recognize the image. In addition, the lower portion of the light guide plate 5 is provided with a reflective sheet 2 for increasing the utilization efficiency of the light source by allowing the light that is not delivered to the liquid crystal panel 6 to be reflected back out of the path and used.

In order to effectively transmit the emitted light to the liquid crystal panel, a plurality of films having various functions are mounted. A Newton's Ring phenomenon caused by mounting a plurality of films or an air layer missing from the contact surface between the films is generated. Light interference occurs such as wet-out phenomenon, light is lost through scattering or absorption as it passes through a plurality of films, and the film is damaged due to physical contact between films. There has been the same problem.

In the conventional prism film, diffusion particles may be provided on the back surface of the substrate layer in addition to the substrate layer and the prism layer constituting the prism film. There was a problem that the loss of light still occurs because it must pass through the substrate layer until reaching.

Accordingly, the present inventors provide a backlight unit assembly that enables the function obtained by mounting three conventional light diffusing films, prism films, and protective films even when the number of mounting sheets is reduced. To solve the above problems, to provide a backlight unit assembly that can significantly reduce the cost and manufacturing process.

Accordingly, the present invention is to provide a backlight unit assembly that can improve the brightness by preventing light loss while evenly spreading the light emitted from the light guide plate.

In addition, the present invention is to provide a backlight unit assembly that can prevent the optical interference phenomenon and damage to the film caused by laminating a plurality of sheets to shorten the manufacturing process and reduce the cost.

In a preferred embodiment of the present invention, an optical substrate including a transparent substrate layer, a light diffusion layer formed on one surface of the transparent substrate layer, the binder resin and the light diffusing particles, and a prism layer formed on the light diffusion layer. Composite film; And it provides a backlight unit assembly comprising a diffusion film located below the optical composite film.

In another preferred embodiment of the present invention, an optical substrate including a transparent substrate layer, a light diffusing layer formed on one surface of the transparent substrate layer, the binder resin and the light diffusing particles, and a prism layer formed on the light diffusing layer. Composite film; And a prism film positioned above or below the optical composite film.

In another preferred embodiment of the present invention, an optical substrate including a transparent substrate layer, a light diffusing layer formed on one surface of the transparent substrate layer, the binder resin and the light diffusing particles, and a prism layer formed on the light diffusing layer. Composite film; And it provides a backlight unit assembly comprising a protective film located on top of the optical composite film.

In the backlight unit assembly according to the embodiment, the light diffusing layer of the optical composite film may include 10 to 500 parts by weight of light diffusing particles having a particle diameter of 1 to 50 ㎛ with respect to 100 parts by weight of the binder resin solid content. have.

In the backlight unit assembly according to the embodiment, the optical complex film may further include a bottom layer including a binder resin and particles on the other side of the transparent substrate layer.

In the backlight unit assembly according to the embodiment, the particles included in the bottom layer of the optical composite film may be the same or different particles from the light diffusing particles of the light diffusing layer.

In the backlight unit assembly according to the embodiment, the prism layer of the optical composite film may have a refractive index of 0.01 to 0.2 higher than the refractive index of the binder resin of the light diffusion layer.

In the backlight unit assembly according to the embodiment, the prism layer of the optical composite film may have a pattern of a linear arrangement structure or a non-linear arrangement structure of the prism structure selected from polygonal, cone, hemispherical and non-spherical.

The present invention can simultaneously provide the function of improving the brightness while evenly spreading the light emitted from the light guide plate or the diffusion plate, significantly shortening the manufacturing process as compared to the case of mounting a light diffusion film and a prism film separately. In addition, cost can be reduced and a thinner liquid crystal display can be provided.

In addition, the present invention can provide a backlight unit assembly capable of preventing the loss of light such as light interference phenomenon, scattering or absorption caused by laminating a plurality of sheets, damage to the film.

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

The backlight unit assembly of the present invention is an optical composite comprising a transparent substrate layer, a light diffusing layer formed on one surface of the transparent substrate layer, the binder resin and light diffusing particles, and a prism layer formed on the light diffusing layer. A backlight unit assembly comprising a film, and a diffuser film positioned below the optical composite film, a backlight unit assembly including a prism film positioned above or below the optical composite film, and an upper portion of the optical composite film. Provided is a backlight unit assembly comprising a protective film positioned at.

The optical composite film has a structure in which a light diffusion layer is formed on one surface of a transparent substrate layer and a prism layer is formed on the light diffusion layer.

First, a polyethylene terephthalate film, a polycarbonate film, a polypropylene film, a polyethylene film, a polystyrene film, or a polyepoxy film may be used as the transparent base layer, and mainly a polyethylene terephthalate film and a polycarbonate film are used. The transparent substrate layer may have a thickness of 10 to 1000 µm, and more preferably 15 to 400 µm, in order to be advantageous in mechanical strength, thermal stability, and flexibility, and to prevent loss of transmitted light.

The light diffusing layer formed on one surface of the transparent base layer is formed by dispersing light diffusing particles in a binder resin, and the binder resin has good adhesion with the transparent base layer and is compatible with dispersed light diffusing particles. This good resin, i.e., one in which the light-diffusing particles are evenly dispersed in the resin, is separated or does not easily precipitate. As such resin, For example, unsaturated polyester, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal butyl methyl methacrylate, acrylic acid, methacrylic acid, hydroxy Ethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, acrylamide, metyrolacrylamide, glycidyl methacrylate, ethyl acrylate, isobutyl acrylate, normal butyl acrylate, 2- Acrylic resins, such as a homopolymer of ethylhexyl acrylate, these copolymers, or a terpolymer, a urethane resin, an epoxy resin, a melamine resin, etc. are used.

In addition, the light diffusing particles included in the light diffusing layer may be dispersed in a single layer or multiple layers, it is preferable to use a particle diameter of 1 ~ 50㎛, 10 to 500 parts by weight based on 100 parts by weight of the solid content of the binder resin It is good to include. When the light diffusing particles having such a particle diameter are included in the above content, an appropriate light diffusing effect may be provided while preventing whitening and separation of the particles.

As the light diffusing particles, a plurality of organic particles or inorganic particles may be used. Typical organic particles used are methyl methacrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylamide, metyrolacrylamide, glycidyl methacrylate, ethyl acrylate. Of acrylic particles of isobutyl acrylate, normal butyl acrylate, 2-ethylhexyl acrylate homopolymer or copolymer and olefinic particles such as polyethylene, polystyrene and polypropylene, copolymer particles of acryl and olefinic copolymer and homopolymer After forming the particles, multi-layered multi-component particles made by covering the layers with other monomers are used. As inorganic particles, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, magnesium fluoride and the like are used. The organic and inorganic particles are merely exemplary and are not limited to the particles of the organic or inorganic materials listed above, and may be replaced by other known materials as long as the main object of the present invention can be achieved. It is obvious to the case of this material change is also within the scope of the technical idea of the present invention.

On the other hand, a prism layer is formed on the light diffusion layer.

As the material constituting the prism layer, a polymer resin containing an ultraviolet curable resin or a thermosetting resin is used, and a resin composition capable of forming a crosslinking bond having excellent transparency and suitable for maintaining the shape of an optical structure can be used. For example, it is possible to use an epoxy resin-ruic acid-based, polyethylol-based, unsaturated polyester-styrene, acrylic or methacrylic acid ester, and the like. Preference is given to using. Such resin types include oligomers such as polyurethane acrylics or methacrylates, epoxy acrylics or methacrylates, polyester acrylics or methacrylates, and are alone or diluted with acrylic or methacrylate monomers having a polyfunctional or monofunctional group. Can be used.

The prism layer in the present invention may have a pattern of a linear array structure or a nonlinear array structure of a prism structure selected from polygonal pyramid, cone, hemispherical and non-spherical.

Meanwhile, according to the exemplary embodiment of the present invention, the prism layer may have a refractive index of 0.01 to 0.2 higher than that of the binder resin forming the light diffusion layer, thereby reducing light loss by reducing total reflection.

In general, as the refractive index of the prism layer is higher, the angle at which light is emitted becomes narrower with respect to the front surface, so that the front luminance may be improved, but the total reflection light increases, thereby increasing the light loss.

The bottom layer may be further formed on the other side of the transparent base layer, that is, the surface other than the surface on which the light diffusion layer is formed, which is formed by dispersing particles in the binder resin. The binder resin of the bottom layer is a resin having good adhesion with the transparent base layer and having good compatibility with the dispersed particles, that is, the particles are uniformly dispersed in the resin and are not separated or precipitated well. It may be the same as the binder resin of the diffusion layer. The particles included in the bottom layer may be organic particles or inorganic particles. For example, the light diffusing particles included in the light diffusing layer may be the same as or different from the particles of the light diffusing layer.

The bottom layer may include 0.01 to 30 parts by weight of particles with respect to 100 parts by weight of the binder resin, which is advantageous for the effect of preventing damage, and in the case of organic particles, light diffusion may weaken the front luminance, In this case, the use of excess may be disadvantageous because light may be reflected or absorbed at the surface of the particle to reduce the light utilization efficiency by weakening the front brightness.

The bottom layer is in contact with the opposing surface or other laminated optical film in the processing apparatus during the loading or storage of the optical film or during the process of assembling the optical film with other parts by the protrusion of the surface formed by the particles dispersed in the binder resin. By reducing the area, it is possible to function to prevent surface damage that may occur during the separation, movement or assembly process to the sheet.

This surface damage prevention effect of the present invention is that when the two optical films are laminated and used in the backlight unit, the protruding particles are different from each other, rather than the direct contact between the prism vertices of the optical film and the smooth surface of the other optical film. In contact with the optical film, the contact area between the optical films is reduced, and the buffering effect by the particles is enabled, thereby preventing damage to the vertex portion of the prism structure on the surface where the prism structure is formed or to prevent surface damage on the opposite surface. Obtained by

In the optical composite film described above, light evenly diffused by the light diffusing particles passing through the transparent substrate layer passes directly through the prism layer, so that the light efficiency can be further improved. Thus, the amount of light loss is greatly reduced as compared with the conventional art. On the other hand, by extending the difference in refractive index between the binder resin and the light diffusing particles in the light diffusing layer can also be provided with concealment. Therefore, the films that were separately manufactured to provide light diffusion, concealment, and brightness increase are manufactured at one time, so that the manufacturing process and cost can be reduced while providing the same level of brightness as using the diffusion film and prism film separately. In addition, since the number of sheets to be mounted in the backlight optical sheet assembly can be reduced, problems caused by stacking a plurality of sheets can be prevented, which is advantageous.

The present invention can provide a backlight unit assembly including a diffusion film or a prism film formed adjacent to one surface of the optical composite film described above, thereby further improving the luminance than when only the optical composite film is mounted. have.

Therefore, when the optical composite film of the present invention is applied to the backlight unit, it is possible to provide a backlight unit assembly having an appropriate brightness and viewing angle relative to the number of sheets to be mounted.

Hereinafter, the present invention will be described in more detail with reference to Preparation Examples and Examples, but the scope of the present invention is not limited to the following Examples.

<Manufacture example 1>

80 parts by weight of methyl ethyl ketone and 60 parts by weight of toluene were weighed and diluted in 100 parts by weight of acrylic resin 52-666 (Aekyung Chemical Co., Ltd.) on one side of a transparent substrate layer of 188 μm ultra-transparent polyethylene terephthalate film FHSS (Kolon). After preparing a binder resin having a refractive index of 1.50, 90 parts by weight of the spherical polymethyl methacrylate particles MH20F (Kolon Co., Ltd.) having an average particle diameter of 20 μm was mixed with the binder resin and coated with a gravure coater. After curing at 120 ° C. for 60 seconds, the light diffusion layer was applied such that the thickness was 20 to 25 μm after drying.

40 parts by weight of high refractive acrylate, 40 parts by weight of urethane acrylate, 15 parts by weight of 2-phenylethyl methacrylate, 3 parts by weight of 1,6-hexanediol acrylate, BAPO-based photoinitiator on one surface of the cured light diffusing layer Applying a photosensitive composition mixed with 2 parts by weight, coating the photosensitive composition applied to the light diffusion layer on the frame of the prism-shaped roller, and irradiated with ultraviolet (Fusion, 300Watt / inch ² ) from the transparent substrate layer of the linear A triangular prism was formed, and a prism layer having a refractive index of 1.55 was formed.

<Manufacture example 2>

Except for forming a non-linear triangular prism on one surface of the light diffusion layer in Preparation Example 1 to prepare an optical composite film in the same manner.

<Manufacture example 3>

On the other side of the ultra-transparent polyethylene terephthalate film in which the prism layer is not formed in Preparation Example 1, 200 parts by weight of methyl ethyl ketone and 150 parts by weight of toluene were diluted in 100 parts by weight of acrylic resin, and then spherical poly having an average particle diameter of 11.5 μm. Methyl methacrylate particles MH10F (Kolon Co., Ltd.) was mixed with 20 parts by weight of the binder resin, dispersed in a mill, and cured at 120 ° C. for 60 seconds, except that the bottom layer was formed to have a thickness of 1 to 3 μm after drying. And the optical composite film was prepared in the same manner.

<Manufacture example 4>

On the other side of the ultra-transparent polyethylene terephthalate film in which the prism layer is not formed in Preparation Example 2, 200 parts by weight of methyl ethyl ketone and 150 parts by weight of toluene were diluted in 100 parts by weight of an acrylic resin, and then spherical poly having an average particle diameter of 11.5 μm. Methyl methacrylate particles MH10F (Kolon Co., Ltd.) was mixed with 20 parts by weight of the binder resin, dispersed in a mill, and cured at 120 ° C. for 60 seconds, except that the bottom layer was formed to have a thickness of 1 to 3 μm after drying. And the optical composite film was prepared in the same manner.

Production Example 5

An optical composite film was manufactured in the same manner as in Example 1, except that the light diffusing particles were dispersed in a stack when the light diffusing layer was formed.

<Manufacture example 6>

An optical composite film was manufactured in the same manner as in Example 2, except that the light diffusing particles were dispersed in a stack when the light diffusing layer was formed.

<Manufacture example 7>

On the other side of the ultra-transparent polyethylene terephthalate film in which the prism layer is not formed in Preparation Example 5, 200 parts by weight of methyl ethyl ketone and 150 parts by weight of toluene were diluted in 100 parts by weight of acrylic resin, and then spherical poly having an average particle diameter of 11.5 μm. Methyl methacrylate particles MH10F (Kolon Co., Ltd.) was mixed with 20 parts by weight of the binder resin, dispersed in a mill, and cured at 120 ° C. for 60 seconds, except that the bottom layer was formed to have a thickness of 1 to 3 μm after drying. And the optical composite film was prepared in the same manner.

<Manufacture example 8>

On the other side of the ultra-transparent polyethylene terephthalate film in which the prism layer is not formed in Preparation Example 6, 200 parts by weight of methyl ethyl ketone and 150 parts by weight of toluene were diluted in 100 parts by weight of acrylic resin, and then spherical poly having an average particle diameter of 11.5 μm. Methyl methacrylate particles MH10F (Kolon Co., Ltd.) was mixed with 20 parts by weight of the binder resin, dispersed in a mill, and cured at 120 ° C. for 60 seconds, except that the bottom layer was formed to have a thickness of 1 to 3 μm after drying. And the optical composite film was prepared in the same manner.

Preparation Example 9

An optical composite film was manufactured in the same manner as in Example 2, except that the binder resin had a refractive index of 1.52 by including a high refractive resin in the manufacture of the binder resin in forming the light diffusion layer.

Production Example 10

An optical composite film was manufactured in the same manner as in Example 4, except that the binder resin had a refractive index of 1.52 by including a high refractive resin in the manufacture of the binder resin in forming the light diffusion layer.

Production Example 11

An optical composite film was manufactured in the same manner as in Example 1, except that the prism layer was formed to have a refractive index of 1.6.

<Examples 1-11>

A light diffusion film (KOLON, Inc., LD602) was laminated and fixed to one surface of the transparent base layer direction of each of the optical composite films of Preparation Examples 1 to 11 in the backlight unit for a 17 inch liquid crystal display panel.

<Examples 12-22>

A protective film (KOLON, Inc. LD143) was laminated and fixed on one surface of the prism layer direction of each of the optical composite films of Preparation Examples 1 to 11 in the backlight unit for a 17 inch liquid crystal display panel.

Comparative Example 1

Prism Film (KOLON, LC213)

Comparative Example 2

A prism film (KOLON, LC213, LC213) was laminated and fixed on one surface of a light diffusion film (KOLON, Inc. LD602) including a bottom layer in a backlight unit for a 17 inch liquid crystal display panel.

Comparative Example 3

A prism film (KOLON, LC213) and a protective film (KOLON, LD143) were laminated and fixed on one surface of a light diffusion film (KOLON, Inc. LD602) including a bottom layer in a backlight unit for a 17-inch liquid crystal display panel.

The physical property evaluation of the said Example and the comparative example was performed as mentioned later, The evaluation result is as Table 1 below.

<Optical Interference Measurement>

Arrangement of a plurality of films mounted in each of the above Examples and Comparative Examples between a plurality of glass plates, by applying pressure to the glass plate to observe the Newton's Ring due to excessive adhesion generated in the film, the occurrence of each phenomenon Relative evaluation was carried out as follows according to the degree. On the other hand, a plurality of optical composite film prepared in the above production example was arranged between a plurality of glass plates to measure the optical interference phenomenon in the same manner.

Newton's Ring: Not Occurred ← ◎-○-△-× → Occurred

<Luminance evaluation (Cd / ㎡)>

In the backlight units of Examples and Comparative Examples, luminance of arbitrary 13 points was measured using a luminance meter (model name: BM-7, TOPCON Japan), and the average value thereof was obtained. On the other hand, the optical composite film prepared in the above production example was fixed to the backlight unit for 17-inch liquid crystal display panel and the brightness was measured in the same manner.

◎: luminance is 4500 cd / m2 or more

(Circle): When luminance is 3500 cd / m <2> or more and 4500 cd / m <2>

(Triangle | delta): When luminance is 3000 cd / m <2> or more and 3500 cd / m <2>

X: luminance is less than 3000 cd / m 2

<Viewing angle>

In the backlight units of Examples and Comparative Examples, a luminance meter (model name: BM-7, Japan TOPCON Co., Ltd.) was used to measure the luminance at the left and right angles of 80 degrees at 10-degree intervals and indicate 1/2 luminance of the maximum luminance. The angle was obtained. On the other hand, the viewing angle was measured in the same manner by fixing the optical composite film prepared in the above Production Example alone to the backlight unit for 17-inch liquid crystal display panel.

<Visibility>

Visual evaluation of the mounting surface was carried out when the light diffusing films of Examples and Comparative Examples prepared above were mounted on a backlight unit for a 17-inch liquid crystal display panel.

 * When the entire surface is uneven and a rainbow shape due to pattern interference, etc. appears ×

 * Even if the entire surface is uneven and rainbow shape due to pattern interference does not appear ○

As a result of the physical property evaluation, in the case of the backlight unit assembly according to the embodiment of the present invention, optical interference did not occur in almost all cases, and it could be seen that the visibility was excellent while maintaining the luminance above an appropriate level.

In addition, it can be seen that the viewing angle is wider than that of Comparative Example 3 in which the light diffusing film and the prism film are laminated.

Therefore, the backlight unit assembly of the present invention increases the utilization efficiency of the light source while minimizing the light loss, and thus can be applied even when the sheet composition is reduced compared to the case where the conventional light diffusing film, prism film, and protective film are all mounted separately. It can be seen that the luminance can be provided and that the viewing angle and visibility are excellent.

1 is a schematic view showing a conventional backlight unit.

Claims (8)

An optical composite film formed on one surface of the transparent substrate layer, the light diffusion layer including a binder resin and light diffusing particles, and a prism layer formed on the light diffusion layer; And And a diffusion film positioned below the optical composite film. An optical composite film formed on one surface of the transparent substrate layer, the light diffusion layer including a binder resin and light diffusing particles, and a prism layer formed on the light diffusion layer; And And a prism film positioned above or below the optical composite film. An optical composite film formed on one surface of the transparent substrate layer, the light diffusion layer including a binder resin and light diffusing particles, and a prism layer formed on the light diffusion layer; And Back light unit assembly comprising a protective film located on top of the optical composite film. The method according to any one of claims 1 to 3, The light diffusing layer is a backlight unit assembly comprising a light diffusing particles having a particle diameter of 1 ~ 50㎛ 10 to 500 parts by weight based on 100 parts by weight of the binder resin solid content. The method according to any one of claims 1 to 3, The backlight unit assembly further comprises a bottom layer comprising a binder resin and particles on the other side of the transparent substrate layer. The method of claim 5, wherein And the particles are the same or different particles as the light diffusing particles of the light diffusing layer. The method according to any one of claims 1 to 3, The prism layer has a refractive index of 0.01 to 0.2 higher than the refractive index of the binder resin of the light diffusion layer, wherein the optical composite film. The method according to any one of claims 1 to 3, The prism layer is optical composite film, characterized in that it has a pattern of linear arrangement or non-linear arrangement of the prism structure selected from polygonal, cone, hemispherical and non-spherical.

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