KR20070089471A - Back light unit and liquid crystal display including the same - Google Patents

Abstract

A backlight unit and an LCD(Liquid Crystal Display) having the same are provided to improve thermal resistance of a diffusion plate by containing a glass fiber material in the diffusion plate. A reflecting plate(220) reflects a leakage light in a downward direction of a light irradiated from a plurality of lamps(210). A diffusion plate(230) diffuses the light irradiated from the lamps and the light reflected from the reflecting plate and contains a glass fiber material of a predetermined rate. An optical sheet(240) concentrates the light diffused by the diffusion plate. The diffusion plate contains the glass fiber material in the rate from 5 % to 30 %. The glass fiber material is mixed with a diffusion medium material in an extruding process to form the diffusion plate. The diffusion medium material is at least one selected from the group consisting of an MS resin, a PMMA resin, a PC resin, and a PET resin. The lamps are LED(Light Emitting Diode) lamps.

Description

Back light unit and liquid crystal display including the same {Back light unit and liquid crystal display including the same}

1A and 1B are schematic diagrams schematically illustrating a backlight unit according to the related art.

2A is a cross-sectional view illustrating a backlight unit according to an exemplary embodiment of the present invention.

FIG. 2B is a graph showing the relationship between the content rate of the glass fiber material of the diffuser plate included in the backlight unit of FIG.

FIG. 3 is a schematic diagram illustrating a liquid crystal display device including the backlight unit of FIG. 2A.

<Explanation of symbols on main parts of the drawings>

210, 322: lamp 220: reflector

230, 324: diffuser plate 240, 326: optical sheet

310: liquid crystal display panel 312: lower substrate

314: upper substrate 320: backlight unit

The present invention relates to a backlight unit and a liquid crystal display device having the same, and more particularly, to a backlight unit having an improved optical characteristic such as luminance uniformity and a liquid crystal display device having the same.

In recent years, liquid crystal displays are spotlighted as display means.

The liquid crystal display performs display functions using the electrical and optical properties of the liquid crystal injected into the panel, and is widely applied to various fields such as computer monitors and mobile communication terminals due to the advantages of small size, light weight, and low power consumption. There is a trend.

Since the liquid crystal display device is not a self-luminous display device but a light receiving type display device, a separate light source such as a back light unit equipped with a lamp is required. That is, by selectively transmitting the light emitted from the backlight unit through the liquid crystal display panel, it is possible to display desired image information.

The backlight unit may be classified into a light guide plate type and a light guide plate type according to the presence or absence of the light guide plate. The backlight unit may include a lamp, an optical sheet, a reflective plate, and the like separately from the presence or absence of the light guide plate.

1A and 1B are schematic diagrams schematically illustrating a backlight unit according to the related art.

1A and 1B, the backlight unit according to the related art may include a lamp 110, a reflector 120, a diffuser plate 130, an optical sheet 140, and the like.

In such a backlight unit, the diffusion plate 130 positioned on the upper portion of the lamp 110 is generally formed of a diffusion medium material such as MS resin, PMMA resin, PC resin, and PET resin. However, since the diffusion medium material is easily deformed by heat, it must be spaced apart from the lamp 110 by a predetermined distance or more, and the light scattering degree is reduced due to the separation distance between the lamp 110 and the diffusion plate 130. There is a problem.

In particular, the LED lamp backlight unit that has been introduced in recent years can be said that the higher the heat generated than the conventional CCFL or EEFL is more likely to cause deformation of the diffusion plate 130. That is, as shown in (a) and (b) of FIG. 1B, the diffusion plate 130 generates a cup shape deformation (a) or a cap shape deformation (b) by heat generation of the lamp 110. ) Is easy to occur, and in this case, optical characteristics such as luminance uniformity of the liquid crystal display may be greatly degraded.

An object of the present invention is to provide a backlight unit having improved optical characteristics such as luminance uniformity and a liquid crystal display device having the same.

The objects of the present invention are not limited to the above-mentioned objects, and other objects which are not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, a backlight unit according to an embodiment of the present invention, a plurality of lamps, a reflector for reflecting the light leaking down from the light irradiated from the plurality of lamps, the light irradiated from the lamp and A diffuser plate comprising a proportion of glass fiber material and scattering light reflected by the reflecting plate, and an optical sheet for collecting light diffused by the diffuser plate.

Herein, the ratio of the glass fiber material included in the diffusion plate may be 5% to 30%. The glass fiber material may be mixed with the diffusion medium material in the extrusion process to constitute the diffusion plate. As the diffusion medium material mixed with the glass fiber material, MS resin, PMMA resin, PC resin, PET resin, and the like, which are widely used as conventional diffusion plate materials, may be used.

At this time, the lamp provided in the backlight unit according to an embodiment of the present invention may be an LED lamp.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be embodied in various forms, and the present embodiments are merely provided to make the disclosure of the present invention complete and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, the invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 2a is a cross-sectional view showing a backlight unit according to an embodiment of the present invention, Figure 2b is a content of the glass fiber material of the diffuser plate provided in the backlight unit of Figure 2a and the resulting light scattering and intensity of the diffuser plate A graph showing the relationship between

First, referring to FIG. 2A, it can be seen that the backlight unit according to the exemplary embodiment includes a lamp 210, a reflecting plate 220, a diffusion plate 230, an optical sheet 240, and the like.

The lamp 210 is configured by parallel arrangement of a plurality of lamps to perform a function of providing light. In the backlight unit according to the exemplary embodiment of the present invention, a fluorescent lamp such as CCFL or EEFL may be used as the lamp 210, but preferably, an LED lamp is used.

The reflecting plate 220 reflects downward leakage light of the light emitted from the lamp 210 to increase the luminance of the liquid crystal display. The reflector plate 220 may be configured by an inner wall of the body of the lamp housing that constrains the lamp 210, and may be formed of a white-based material having a high reflectance or a material such as silver (Ag) or aluminum (Al).

The diffusion plate 230 scatters the light irradiated from the lamp 210 and the light reflected from the reflecting plate 220 to uniform the luminance distribution of the liquid crystal display. Here, the diffusion plate 230 provided in the backlight unit according to the embodiment of the present invention is configured to include a glass fiber (glass fiber) material in order to minimize deformation due to heat generated from the lamp 210, etc. It is characterized by.

In other words, a diffusion plate 230 is formed through an extrusion process by mixing a diffusion medium material such as MS resin, PMMA resin, PC resin, and PET resin with a glass fiber material to form a diffusion plate 230. The plate 230 will be able to be implemented.

In this case, the mixing ratio of the glass fiber material is preferably about 5% to 30% of the total diffusion plate, because the light scattering degree of the diffusion plate 230 is reduced when the glass fiber material content is too high, the glass fiber This is because when the content of the material is too small, the characteristics of the diffusion plate 230 such as heat resistance are improved and do not appear. Graphs of the content of glass fiber materials, the resulting heat resistance and light scattering are shown in FIGS. 2B and 2B, respectively.

The optical sheet 240 condenses the light scattered by the diffusion plate 230 to increase the luminance of the liquid crystal display. The optical sheet 240 may be a prism sheet such as a horizontal sheet and / or a vertical sheet.

FIG. 3 is a schematic diagram illustrating a liquid crystal display device including the backlight unit of FIG. 2A.

Referring to FIG. 3, it can be seen that the LCD including the backlight unit according to the exemplary embodiment of the present invention includes the liquid crystal display panel 310, the backlight unit 320, and the like as a whole.

The liquid crystal display panel 310 includes a lower substrate 312, an upper substrate 314, and a liquid crystal layer (not shown) formed between the two substrates 312 and 314.

Typically, the lower substrate 312 includes a gate line, a data line, a thin film transistor, a pixel electrode, and the like, and the upper substrate 314 is positioned on the upper side of the lower substrate 312 to face the color filter, the black matrix, and the common electrode. But not shown.

The configuration and operation thereof are briefly described as follows.

First, a plurality of gate lines and data lines are arranged on the lower substrate 312 to have a matrix form of m × n. Thin film transistors, which are switching elements, are formed at intersections of the plurality of gate lines and data lines.

Although not shown in detail, the thin film transistor includes a gate electrode, a source electrode, a drain electrode, an active layer, an ohmic contact layer, and the like, and the drain electrode is connected to the pixel electrode to form a unit pixel. In other words, when the gate signal is applied to the gate electrode through the gate line, the thin film transistor operates to transfer the data signal applied to the data line from the source electrode to the drain electrode through the ohmic contact layer and the active layer.

That is, when a data signal is applied to the source electrode, a voltage corresponding thereto is applied to the pixel electrode connected to the drain electrode, which causes a voltage difference between the pixel electrode and the common electrode. In addition, due to the voltage difference between the pixel electrode and the common electrode, the molecular arrangement of the liquid crystal interposed therebetween changes, and the light transmittance of the pixel changes due to the change in the molecular arrangement of the liquid crystal, thereby changing the data signal applied to each pixel. The color difference of the pixel is generated according to the difference. By using the color difference, the screen of the LCD may be controlled.

The gate signal applied to the gate line and the data signal applied to the data line are generated by driving circuits such as a gate driver and a data driver, respectively, and between the driving circuit and the liquid crystal display panel 310 is a tape carrier package (TCP) or the like. Can be connected by The TCP may be made of a flexible material, and in this case, the driving circuit may be located on the back of the backlight unit 320 by bending of the TCP.

In this case, although the color filter, the common electrode, and the like have been described in the upper substrate 314 in general, the common electrode may be formed on the lower substrate 312 in the case of a horizontal alignment type (IPS mode) liquid crystal display device, In the case of a color-filter on array (COA) type liquid crystal display device, the color filter may be formed on the lower substrate 312, which is obvious to those skilled in the art, and thus detailed description thereof will be omitted.

The backlight unit 320 includes a lamp 322, a diffusion plate 324, an optical sheet 326, and the like.

As the lamp 322 applied to the liquid crystal display according to the exemplary embodiment of the present invention, a fluorescent lamp such as CCFL or EEFL may be used, but it is more preferable that the LED lamp array is provided as shown.

The diffusion plate 324 is formed through an extrusion molding process by mixing a diffusion medium material such as MS resin, PMMA resin, PC resin and PET resin and glass fiber material. In this case, the content rate of the glass fiber material may be about 5% to 30% in consideration of light scattering degree, heat resistance, and the like of the diffusion plate 324. As a result, the heat resistance of the diffusion plate 324 may be increased so that deformation due to heat may not occur, whereby the diffusion plate 324 and the lamp 322 may be disposed closer to each other. Optical properties such as luminance uniformity can be improved.

The optical sheet 326 condenses the light scattered by the diffusion plate 324 to increase the brightness of the liquid crystal display, and is composed of a prism sheet such as a horizontal sheet and / or a vertical sheet as described above. .

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, the embodiments described above are to be understood in all respects as illustrative and not restrictive.

According to the backlight unit of the present invention and the liquid crystal display device having the same, the heat resistance of the diffusion plate can be improved by mixing the glass fiber material with the diffusion plate.

As a result, the arrangement interval between the lamp and the diffusion plate can be reduced, and the deformation of the diffusion plate due to the heat generation of the lamp can be prevented, thereby greatly improving optical characteristics such as luminance uniformity of the liquid crystal display device. There is such an advantage.

In particular, the diffusion plate provided in the backlight unit according to the embodiment of the present invention may work much more advantageously when applied to a liquid crystal display device employing a high heat generation LED lamp, the use of which is rapidly increasing in recent years.

Claims (6)

Multiple lamps; A reflecting plate for reflecting light leaking downward of light emitted from the plurality of lamps; A diffuser plate which scatters the light irradiated from the lamp and the light reflected by the reflecting plate and comprises a ratio of glass fiber material; And And an optical sheet for collecting light diffused by the diffusion plate. The method of claim 1, The ratio of the glass fiber material contained in the diffusion plate is a backlight unit, characterized in that 5% to 30%. The method of claim 2, And the glass fiber material is mixed with the diffusion medium material in the extrusion process to form the diffusion plate. The method of claim 3, wherein The diffusion medium material is a backlight unit, characterized in that at least one material selected from the group of MS resin, PMMA resin, PC resin and PET resin. The method of claim 4, wherein And the lamp is a light emitting diode (LED) lamp. A liquid crystal display device comprising the backlight unit according to any one of claims 1 to 5.

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