KR20070025915A - Reflection plate and method for manufacturing the same and back light unit and liquid crystal display device fabricated with it - Google Patents

Abstract

A reflector, a method of fabricating the reflector, a back light unit using the reflector, and an LCD(Liquid Crystal Display) are provided to efficiently radiate heat generated from a lamp to improve the quality of reflector and reduce the thickness of the reflector. A back light unit includes a light-emitting lamp(100), a light guide plate(200), a lamp housing(300), a reflector(500), and a cover bottom(600). The light guide plate converts light generated by the light-emitting lamp into plane light and projects the plane light. The lamp housing condenses the light generated by the light-emitting lamp to a light-receiving face of the light guide plate. The reflector envelops a predetermined part of the light guide plate to upwardly reflect light leaks to the outside and is formed of a material with high thermal conductivity and a reflective material. The cover bottom supports the lamp housing and the light guide plate.

Description

Reflection plate and method for manufacturing the same and back light unit and liquid crystal display device using the same {reflection plate and method for manufacturing the same and back light unit and liquid crystal display device fabricated with it}

1 is a schematic exploded perspective view showing a typical liquid crystal display module

2 is a plan view showing a conventional backlight unit

3 is a perspective view showing a conventional backlight unit according to line II-II of FIG.

Figure 4 is a cross-sectional view showing the configuration of the lamp housing in the conventional backlight unit

5A to 5C are cross-sectional views showing reflecting plates according to the present invention.

6 is a perspective view showing a backlight unit according to a first embodiment of the present invention;

7 is a perspective view showing a backlight unit according to a second embodiment of the present invention;

8 is a graph showing a reflectance comparison (total reflection characteristics) according to the refractive index of the adhesive in the conventional reflector and the functional reflector according to the present invention

Explanation of symbols for the main parts of the drawings

100: light emitting lamp 200: light guide plate

300: lamp housing 400: optical sheet

500: reflector 510: high thermal conductivity material

520: reflective material 530: adhesive

600: cover bottom 700: liquid crystal display panel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a reflector plate and a method of manufacturing the same, and a backlight unit and a liquid crystal display device using the same to ensure temperature uniformity.

A typical liquid crystal display device is composed of a liquid crystal display module, a driving circuit portion and a case for driving the liquid crystal display module.

First, the liquid crystal display module is composed of liquid crystal cells in which a liquid crystal is injected between two glass substrates bonded to each other with a predetermined gap and arranged in a matrix form, and switch elements for switching signals supplied to the liquid crystal cells, respectively. A liquid crystal display panel and a back light unit for irradiating light to the rear surface of the liquid crystal display panel.

In addition, optical sheets are arranged in the liquid crystal display module to scatter and diffuse light traveling from the backlight unit toward the liquid crystal display panel.

In order to prevent light loss, the liquid crystal display panel, the backlight unit, and the optical sheet must be fastened in an integrated form and protected from damage by external impact.

To this end, a top case is configured to surround the backlight unit and the optical sheets including the edge of the liquid crystal display panel.

Since the liquid crystal display module includes a glass substrate, it may be easily damaged by an external impact, so that a top case is used to surround and protect the exterior of the liquid crystal display module in order to prevent damage to the liquid crystal display module due to an external impact.

1 is an exploded perspective view showing a general liquid crystal display device.

As shown in FIG. 1, it consists of the liquid crystal display panel 30 which displays an image, and the backlight unit which irradiates light to the liquid crystal display panel 30. FIG.

Here, the backlight unit is attached to one side of the fluorescent lamp 31 for generating light, the lamp housing 32 surrounding the fluorescent lamp 31 in a U-shape, and one side of the liquid crystal display panel 30 in turn. The diffusion sheet 38, the first prism sheet 37, the second prism sheet 36, the protective sheet 35, the light guide plate 33, and the reflecting plate 34 are formed.

The liquid crystal display panel 30 and a cover bottom 39 for accommodating and fixing the backlight unit are configured.

On the other hand, the backlight unit serves to illuminate the display area A of the liquid crystal display panel 30. Although not shown in the drawing, the display area A of the liquid crystal display panel 30 is composed of two transparent substrates having a polarizing plate attached to an outer surface thereof and a liquid crystal injected between the inner surfaces of the two transparent substrates.

The liquid crystal display device configured as described above is composed of a driving circuit 40 for driving the liquid crystal display panel 30.

The backlight unit operates in the following manner. When the fluorescent lamp 31 provided at one end surface of the light guide plate 33 generates light, the light generated by the fluorescent lamp 31 is collected by the lamp housing 32 and emitted, and the lamp housing ( The light condensed at 32 is transmitted to an end surface of the light guide plate 33 in which the fluorescent lamp 31 is not installed through the end surface of the light guide plate 33.

Then, the light transmitted to the end portion of the light guide plate 33 is spread over the entire surface of the light guide plate 33, and the light is reflected by the diffusion sheet 38 on the display area A of the liquid crystal display panel 30. You lose.

In the liquid crystal display device, a thin film transistor formed in the liquid crystal panel controls a pixel according to a signal from a driving circuit of the liquid crystal display device to selectively pass the light reflected on the display area. The pixels passing through the light selectively gather to display an image on the display area of the liquid crystal panel.

Hereinafter, a backlight unit according to the prior art will be described with reference to the accompanying drawings.

FIG. 2 is a plan view showing a conventional backlight unit, and FIG. 3 is a perspective view showing a conventional backlight unit taken along line II-II of FIG.

2 and 3, a lamp for generating light and a lamp for condensing the light generated by the light emitting lamp 51 in one direction while fixing the light emitting lamp 51. A light guide plate 53 for converting light incident from the light emitting lamp 51 into a surface light source and supplying the light to a liquid crystal display panel (not shown); and a rear surface of the light guide plate 53. Reflector plate 54 for reflecting light toward the liquid crystal display panel, an optical sheet 55 mounted on the light guide plate 53 to increase the brightness of light, and an assembly of the lamp housing 52 and light guide plate 53. It is configured to include a cover bottom (56) for supporting the.

Here, a cold cathode fluorescent lamp is mainly used as the light emitting lamp 51, and the light guide plate 53 is formed with a scattering pattern for scattering light totally reflected therein, which is divided into a display area and a non-display area. .

In addition, the light incident from the light emitting lamp 51 into the light guide plate 53 through the light incident surface existing on the side surface of the light guide plate 53 passes through the non-display area toward the display area while being totally reflected.

The reflector plate 54 installed on the lower surface of the light guide plate 53 re-reflects light emitted from the lower surface of the light guide plate 53 to increase light utilization efficiency.

Figure 4 is a cross-sectional view showing the configuration of the lamp housing in the backlight unit according to the prior art.

As shown in FIG. 4, the lamp housing 52 includes aluminum (Al) 52a and a reflective film (for example, a film having reflective characteristics of a material such as PET or PP) 52b by an adhesive 52c. It is attached.

Here, the reflective film 52b is configured inside and the aluminum 52a is configured outside. That is, a portion of the reflective film 52b is configured on the inner surface to reflect the light generated by the light emitting lamp 51 in one direction, and the aluminum 52a externally heats the heat generated by the light emitting lamp 51. It is formed on the outer surface to discharge into.

On the other hand, in the backlight unit according to the prior art, the reflecting plate 52 is subjected to a back coating treatment on a reflective film (for example, a film having reflective characteristics of materials such as poly ethylene terephthalate (PET) and poly propylene)). In form.

However, the above conventional backlight unit has the following problems.

That is, by including a reflector film and a lamp housing made of a reflective film or aluminum, heat generated from the lamp is being radiated to the cover bottom through the lamp housing, but the heat radiation efficiency is not good.

In addition, due to the high temperature heat, light leakage occurs in the upper and lower corners of the screen due to the deformation of the optical sheet and the deformation of the wide viewing angle polarizer formed under the liquid crystal panel.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and the reflector plate and its manufacturing method to improve the quality and reduce the thickness by heat dissipating heat generated from the lamp to the outside more efficiently and the backlight unit and the liquid crystal display using the same The purpose is to provide a device.

Reflective plate according to the present invention for achieving the above object is characterized in that it comprises a high thermal conductive material, and a reflective material constituted in combination with the high thermal conductive material.

In addition, the method of manufacturing a reflector according to the present invention for achieving the above object comprises the steps of preparing a high thermal conductive material and a reflective material, and forming a combination of the high thermal conductive material and the semi-acid material. It is characterized by.

In addition, the backlight unit according to the present invention for achieving the above object is a light emitting lamp for generating light, a light guide plate for converting the light generated by the light emitting lamp to a surface light source and the light emitted from the light emitting lamp Condensed light is emitted to the incident surface of the light guide plate and is emitted to surround the lamp housing, the back surface of the light guide plate and the incident surface of the light guide plate to reflect the light leaking to the upper side again and combine the high thermal conductivity material and the reflective material And a cover bottom for supporting the lamp housing and the light guide plate.

Hereinafter, a reflective plate according to the present invention, a method for manufacturing the same, and a backlight unit and a liquid crystal display using the same will be described in detail with reference to the accompanying drawings.

5A to 5C are cross-sectional views showing reflecting plates that can be formed by the present invention.

First, as shown in FIG. 5A, the reflective plate 500 includes a reflective material 520 on the high thermal conductive material 510.

Here, the high thermal conductivity material 510 uses at least one of graphite, aluminum, copper, carbon nanotubes (CNT), and AlSiC in a sheet or plate form.

Here, the reflective material 520 is used at least one of materials such as Ag, Al ₂ O ₃ , TiO ₂ , Al, PET, optical fiber, and the like is used by coating the scattering material thereon.

In this case, a shielding layer made of an additional material may be formed under the reflective material 520 to improve shielding and stiffness.

In addition, the high thermal conductivity material 510 is formed to have a thickness of about 0.08 mm to 0.20 mm.

On the other hand, the reflector plate 500 according to the present invention has a thickness of 150 ~ 250㎛ when used for the monitor, 115 ~ 225㎛ when used as a notebook PC.

The reflective plate 500 according to the present invention is formed by depositing the reflective material 520 on the high thermal conductive material 510 in a physical vapor deposition (PVD) or sputtering method, or the conventional reflective material 520 and the high thermal conductive material 510. ) Is formed by laminating or coating.

Meanwhile, the reflective material 520 forms a plurality of diffusion beads 522 having a granular shape on the AlNd layer 521, and coats the diffusion material 523 thereon to increase the reflectance. .

In addition, as shown in FIG. 5B, the high thermal conductive material 510 and the reflective material 520 are attached to the reflective plate 500 using the adhesive 530 between the high thermal conductive material 510 and the reflective material 520. Can also be used.

That is, the high thermal conductive material 510 is formed on the protective layer 540, the adhesive 530 is formed on the high thermal conductive material 510, and the high thermal conductive material 510 on which the adhesive 530 is formed. The reflective material 520 may be formed and used thereon.

Here, if the refractive index of the adhesive 530 is reduced, the original reflectance can be maintained even if the thickness of the reflective material 520 is reduced. That is, the thickness of the reflective material 520 can be reduced by reducing the refractive index of the adhesive 530, so that the thickness of the reflective plate 500 can be reduced as a whole.

In addition, when a material such as graphite is used as the high thermal conductive material 510, the high thermal conductive material 510 has a narrower width than the reflective material 520, and the protective layer 540 has the high thermal conductive material 510. It is formed while completely covering the bottom and side of the high thermal conductive material 510 prevents the outflow of foreign matter and at the same time to prevent the graphite and the like outflow.

In addition, the adhesive 530 may be made of a double-sided adhesive tape.

Here, the reflective material 520 may be formed by forming a shielding layer under the reflective material 520.

The high thermal conductivity material 510 has a thickness of 60 to 120 μm, the adhesive 530 to have a thickness of 20 to 40 μm, and the reflective material 520 to have a thickness of 60 to 100 μm. do.

In addition, as illustrated in FIG. 5C, a plurality of reflective materials 520 may be stacked on the high thermal conductive material 510.

6 is a perspective view showing a backlight unit according to a first embodiment of the present invention.

As shown in FIG. 6, the liquid crystal display panel 700 displaying an image, the light emitting lamp 100 generating light, and the light incident from the light emitting lamp 100 are converted into a surface light source to convert the light into a surface light source. The light guide plate 200 to be supplied to the 700 and the light emitting lamp 100 are fixed to one side of the light guide plate 200, and the light generated by the light emitting lamp 100 is focused on the incident surface of the light guide plate 200. And a lamp housing 300 formed by stacking the high thermal conductive material and the reflective material, and surrounding the back and the incident surface of the light guide plate 200 to reflect light toward the liquid crystal display panel 700, and the high thermal conductive material and Reflector plate 500 formed by stacking reflective materials, an optical sheet 400 installed on the light guide plate 200 to increase brightness of light, and an assembly of the lamp housing 300 and the light guide plate 200. Cover bottom (600) It is configured to hereinafter.

Here, a cold cathode fluorescent lamp is mainly used as the light emitting lamp 100, and the light guide plate 200 is formed with a scattering pattern for scattering light totally reflected therein, and is divided into a display area and a non-display area. .

In addition, the light incident from the light emitting lamp 100 into the light guide plate 200 through the incident surface existing on the side surface of the light guide plate 200 passes through the non-display area toward the display area while being totally reflected.

Some of the light proceeding is slightly emitted through the upper surface of the light guide plate 200 while the total reflection condition is broken by the scattering pattern formed in the light guide plate 200 to provide a surface light source to the liquid crystal display panel.

Meanwhile, the backlight unit of the present invention uses the lamp housing 300 and the reflecting plate 500 in a form in which a high thermal conductive material and a reflective material having excellent thermal conductivity are combined to use the high heat generated by the light emitting lamp 100. The lamp housing 300 and the reflecting plate 500 may effectively radiate heat toward the outside air and the cover bottom 600.

In addition, the reflective plate 500 may be formed to extend to a part of the upper surface of the light guide plate 200 while surrounding the incident surface of the light guide plate 200.

The light emitting lamp 100 may include any one of red, green, and blue light emitting diodes, a plurality of white light emitting diodes, an external electrofluorescent lamp (EEFL), and a cold cathode fluorescent lamp (CCFL).

In addition, the optical sheet 400 is a diffusion sheet, at least one prism sheet, and a protective sheet are sequentially stacked on the upper surface of the light guide plate 200, the diffusion sheet is a prism sheet for light emitted from the upper surface of the light guide plate 200 Optimizing the uniformity and direction of the light in the incident process, the prism sheet serves to prevent the bad image and the direction control to focus the incident light in the desired direction through this process, the protective sheet protects the prism sheet It improves the light uniformity and spreads the light output direction properly to increase the viewing angle of the surface light source.

7 is a cross-sectional view schematically illustrating a backlight unit according to a second embodiment of the present invention.

As shown in FIG. 7, the backlight unit includes a plurality of light emitting lamps 100 for generating light, a cover bottom 600 for accommodating the plurality of light emitting lamps 100, and a cover bottom 600. An optical sheet 400 covering the upper surface and diffusing and condensing the incident light from the plurality of light emitting lamps 100 to the entire area, and a liquid crystal display for receiving an image of the light incident through the optical sheet 400 to display an image; It comprises a panel 700.

Here, each of the light emitting lamps 100 mainly uses a cold cathode fluorescent lamp. Such a plurality of light emitting lamps 100 are turned on lamp driving voltages from an inverter (not shown) to irradiate light to the back surface of the optical sheet 400.

In addition, the cover bottom 600 supports and accommodates the plurality of light emitting lamps 100. The inner wall of the cover bottom 600 is attached with a reflective plate 500 formed by stacking a high thermal conductive material and a reflective material to reflect light incident from the plurality of light emitting lamps 100 toward the optical sheet 400. .

Meanwhile, the optical sheet 400 covers a top surface of the cover bottom 600 and diffuses the light incident from the plurality of light emitting lamps 100 to the entire area, and is disposed on the diffuser plate and diffuses. It consists of a prism sheet which collects light from a plate.

8 is a graph showing a reflectance comparison (total reflection characteristics) according to the refractive index of the adhesive in the conventional reflector and the functional reflector according to the present invention.

As shown in FIG. 8, the reflectance A of the reflector plate according to the prior art is 0.178 to 0.914 at the minimum, and is 0.291 on average.

On the contrary, when the refractive index of the adhesive is 1.41 in the functional reflector according to the present invention, the reflectance B of the reflector is at least 0.190 to at most 0.908, on average 0.276.

In addition, when the refractive index of the adhesive is 1.30 in the functional reflector according to the present invention, the reflectance (C) of the reflector is at least 0.221 and at most 0.908, on average 0.303.

Therefore, although the reflectance of the reflector according to the prior art has an average of 0.291, when using a material such as PET having a refractive index of 1.41, which is a general adhesive in the functional reflector according to the present invention has a reflectance of 0.276 on average, it is lower than the conventional When the refractive index of the general adhesive is lowered to 1.30, the reflectance can be increased on average than in the related art.

In conclusion, when laminating a conventional reflector and a functional semi-reflective plate made of a reflective material and a high thermal conductive material according to the present invention, it can be seen that the reflectance varies according to the refractive index of the adhesive. In addition to reducing the overall reflector thickness.

On the other hand, the refractive index according to the wavelength (unit: nm) of each material used as the adhesive is shown in Table 1 as follows.

PMMA Polystyrene Polycarb SAN PET NAS TPFE 365.0 nm 1.5136 1.6431 1.6432 1.6125 ― ― ― 404.7 nm 1.5066 1.6253 1.6224 1.5971 ― ― ― 435.8 nm 1.5026 1.6154 1.6115 1.5886 ― ― ― 480.0 nm 1.4983 1.6052 1.6007 1.5800 1.6870 ― ― 486.1 nm 1.4978 1.6041 1.5994 1.5790 ― 1.5740 ― 546.1 nm 1.4938 1.5950 1.5901 1.5713 1.6680 ― ― 587.6 nm 1.4918 1.5905 1.5855 1.5674 1.6600 ― ― 589.3 nm 1.4917 1.5903 1.5853 1.5673 ― 1.5640 1.3100 643.9 nm 1.4896 1.5858 1.5807 1.5634 1.6510 ― ― 656.3 nm 1.4892 1.5949 1.5799 1.5627 ― 1.5580 ― 706.5 nm 1.4878 1.5820 1.5768 1.5601 ― ― ― 852.1 nm 1.4850 1.5762 1.5710 1.5551 ― ― ― 1014.0 nm 1.4831 1.5726 1.5672 1.5519 ― ― ―

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

As described above, the reflector according to the present invention, a method of manufacturing the same, and a backlight unit and a liquid crystal display using the same have the following effects.

First, the lamp housing and the reflector are composed of a high thermal conductivity material and a reflective material having excellent thermal conductivity, thereby effectively radiating heat generated from the lamp to the outside through the cover bottom, thereby ensuring temperature uniformity of the liquid crystal display and increasing the temperature. It is possible to improve the reliability of the device by preventing the lowering of the brightness and the deformation of the optical component.

Second, since the adhesive formed between the high thermal conductive material and the reflective material constituting the reflective plate is formed of a material having a low refractive index, the thickness of the reflective plate can be maintained while reducing the thickness of the reflective material, thereby reducing the overall thickness of the reflective plate.

Claims (21)

High heat conductive materials, Reflector comprising a reflective material coupled to the high thermal conductivity material. The reflective plate of claim 1, wherein the high thermal conductive material is at least one of graphite, aluminum, copper, carbon nanotubes (CNT), and AlSiC in sheet or plate form. The reflecting plate of claim 1, wherein the reflective material is at least one of Ag, Al ₂ O ₃ , TiO ₂ , Al, PET, and an optical fiber. The reflecting plate of claim 1, wherein the reflective material and the high thermal conductive material are bonded by laminating, coating, PVD, and sputtering methods. The reflecting plate of claim 1, wherein the high thermal conductive material has a narrower width than the reflective material. The reflecting plate of claim 1, further comprising a protective layer covering and forming a bottom surface and a back surface of the high thermal conductive material. Preparing a heat sink made of a high thermal conductive material; And forming a reflective material on the high thermal conductivity heat sink. The method of claim 7, wherein the reflective material is formed by PVD or sputtering. The method of claim 7, wherein the reflective material comprises at least one of Ag, Al ₂ O ₃ , TiO ₂ , Al, PET, and an optical fiber. Preparing a reflector made of a reflective material; And forming a high thermal conductive material on the reflecting plate. The method of claim 10, wherein the high thermal conductive material is formed by laminating or coating. The reflector of claim 10, wherein the high thermal conductive material is one of graphite, aluminum, copper, carbon nanotube (CNT), and AlSiC in the form of sheet or powder. Manufacturing method. With a light emitting lamp to generate light, A light guide plate for converting the light generated by the light emitting lamp into a surface light source and emitting the light; A lamp housing condensing the light generated by the light emitting lamp to the incident surface of the light guide plate and emitting the light; A reflection plate configured to surround the back surface of the light guide plate and the incident surface of the light guide plate, reflecting light leaking outward to the upper side, and a high thermal conductive material and a reflective material stacked thereon; And a cover bottom for supporting the lamp housing and the light guide plate. The backlight unit of claim 13, further comprising an optical sheet configured on the light guide plate. The backlight unit of claim 13, wherein the reflecting plate extends to a portion of an upper side of the light guide plate while surrounding the incident surface of the light guide plate. The backlight unit of claim 13, wherein the light emitting lamp comprises one of red, green, and blue light emitting diodes, a plurality of white light emitting diodes, a tube, and a surface-shaped fluorescent lamp. The backlight unit of claim 13, wherein the reflective material is at least one of Ag, Al ₂ O ₃ , TiO ₂ , Al, PET, and an optical fiber. The backlight of claim 13, wherein the high thermal conductivity material is at least one of graphite, aluminum, copper, carbon nanotubes (CNT), and AlSiC in sheet and powder form. unit. A plurality of light emitting lamps generating light, A cover bottom for holding and supporting the plurality of light emitting lamps; An optical sheet covering an upper surface of the cover bottom and diffusing and condensing light from the plurality of light emitting lamps; And a reflecting plate formed by stacking a high thermal conductive material and a reflecting material to reflect light incident from the plurality of light emitting lamps toward the optical sheet on the inner wall of the cover bottom. A liquid crystal display panel displaying an image, With a light emitting lamp to generate light, A light guide plate for converting the light generated by the light emitting lamp into a surface light source and emitting the light to the rear surface of the liquid crystal display panel; A lamp housing condensing the light generated by the light emitting lamp to the incident surface of the light guide plate and emitting the light; A reflection plate formed to cover the back surface of the light guide plate and the incident light incident surface of the light guide plate, in which a high thermal conductive material and a reflective material are stacked to reflect light leaking to the liquid crystal display panel; And a cover bottom for supporting the lamp housing and the light guide plate. A plurality of light emitting lamps generating light, A cover bottom for holding and supporting the plurality of light emitting lamps; An optical sheet covering an upper surface of the cover bottom and diffusing and condensing light from the plurality of light emitting lamps; A reflecting plate formed by stacking a high thermal conductive material and a reflecting material on the inner wall of the cover bottom to reflect the light incident from the plurality of light emitting lamps toward the optical sheet; And a liquid crystal display panel configured on the optical sheet and configured to display an image by receiving light incident through the optical sheet.

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