KR20120067088A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: A liquid crystal display device is provided to increase Ton/Toff characteristic of liquid crystal through temperate increase of a display panel and to reduce MPRT(Moving Picture Response Time). CONSTITUTION: A bottom cover(70) accepts a backlight unit. The bottom cover is formed in mold material. The bottom cover insulates heat which is generated from light sources and a light source driver. The bottom cover embeds at least one heat disperse members(71A). The heat disperse members increase surface temperature of an LCD panel.

Description

[0001] LIQUID CRYSTAL DISPLAY DEVICE [0002]

The present invention relates to a liquid crystal display device capable of improving the response characteristics of the liquid crystal.

Liquid crystal displays have a wide range of applications due to their light weight, thinness, and low power consumption. They are used for portable computers such as notebook PCs, office automation equipment, audio / video equipment, and indoor / outdoor advertising displays. . The transmissive liquid crystal display device, which occupies most of the liquid crystal display device, displays an image by controlling an electric field applied to the liquid crystal layer to modulate the light incident from the backlight unit.

In the liquid crystal display, when the response characteristic of the liquid crystal is deteriorated, a moving picture response time (hereinafter, referred to as "MPRT") becomes long, resulting in motion blurring. Therefore, in order to improve the display quality of a liquid crystal display device, it is required to improve the response characteristic of a liquid crystal.

In order to improve the response characteristics of the liquid crystal, 1) a method of changing the cell gap, 2) a method of changing the properties of the liquid crystal by changing the liquid crystal material, and 3) a surface temperature of the display panel is raised to The method of improving the Ton / Toff characteristics may be considered. Among them, the methods 1) and 2) are difficult to adopt in reality because of the technical difficulties and the burden on the cost. In contrast, method 3) can be considered relatively easily.

The surface temperature of the display panel is greatly affected by the heat generated by the light source driver. The light source driver is used to drive the light sources of the backlight unit, and is disposed on the bottom of the bottom cover to accommodate the backlight unit. Conventionally, the bottom cover is formed of a metal material to facilitate strength maintenance and heat dissipation. Since the bottom cover made of metal emits heat generated from the light source driver in all directions, it is difficult to contribute to the increase of the surface temperature of the display panel. As a result, in the conventional liquid crystal display, it is difficult to improve the Ton / Toff characteristics of the liquid crystal due to the bottom cover made of metal.

Accordingly, an object of the present invention is to provide a liquid crystal display device which can reduce the MPRT by improving the Ton / Toff characteristics of the liquid crystal by increasing the surface temperature of the display panel.

In order to achieve the above object, the liquid crystal display device according to an embodiment of the present invention comprises a liquid crystal display panel; A backlight unit radiating light onto the liquid crystal display panel; A light source driver for driving light sources of the backlight unit; And housing the backlight unit and forming a mold to insulate heat generated from the light sources and the light source driver to increase the surface temperature of the liquid crystal display panel and to conformity to the surface temperature of the liquid crystal display panel. It has a bottom cover containing at least one heat dissipation member for improving the.

The heat dissipation member is implemented with an iron core of a lattice structure.

The heat dissipation member is embedded in a horizontal portion of the bottom cover facing the liquid crystal display panel; The light source driver is disposed on the rear surface of the horizontal portion.

The bottom cover is obtained by inserting the iron core of the lattice structure together with the mold in a mold for forming the bottom cover, followed by injection molding.

The strength of the bottom cover is reinforced by the heat dissipation member.

The backlight unit may include a light source array, a light guide plate for converting light incident from the light source array into planar light, and outputting the light to the liquid crystal display panel, an optical sheet disposed between the liquid crystal display panel and the light guide plate, and a reflection disposed under the light guide plate. It is embodied as an edge type comprising a sheet.

The backlight unit may include a light source array, a diffuser plate for diffusing light incident from the light source array to the liquid crystal display panel, an optical sheet disposed between the liquid crystal display panel and the diffuser plate, and a reflection disposed below the light source array. It is implemented as a direct type including a sheet.

The light sources include at least one or more of a light emitting diode (LED), a hot cathode fluorescent lamp (HCFL), a cold cathode fluorescent lamp (CCFL), and an external electrode fluorescent lamp (EEFL).

The liquid crystal display according to the present invention improves the Ton / Toff characteristics of the liquid crystal without increasing technical difficulty or cost by increasing the surface temperature of the liquid crystal panel using a bottom cover made of a mold material. In this way, the present invention can significantly increase the display quality by reducing the MPRT. In addition, the present invention can greatly contribute to the weight reduction of the liquid crystal display through the bottom cover made of a mold material.

In addition, the liquid crystal display according to the present invention may enhance the panel temperature uniformity and reinforce the bottom cover by embedding the iron core of the lattice structure in the bottom cover.

1 is an exploded perspective view of a liquid crystal display including an edge type backlight unit according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the liquid crystal display shown in FIG. 1.
3 shows the thermal conductivity of a mold compared to the thermal conductivity of a metal.
4A and 4B show front and cross-sectional views, respectively, of a bottom cover including a lattice structure core;
5 is a view showing the heat transfer flow by the bottom cover of the mold according to the present invention in comparison with the heat transfer flow by the bottom cover of the conventional metal.
6 is a view showing a temperature increase effect of the bottom cover of the mold according to the present invention in comparison with the case of using a bottom cover of the conventional metal.
7 is a view showing the specific gravity of the bottom cover of the mold according to the present invention in comparison with the specific gravity of the bottom cover of the conventional metal.
8 is a view showing the MPRT by the bottom cover of the mold according to the present invention in comparison with the MPRT by the bottom cover of the conventional metal.
9A is a partial cross-sectional view of a liquid crystal display device including a direct type backlight unit using a lamp as a light source.
9B is a partial cross-sectional view of a liquid crystal display device including a direct type backlight unit using LED as a light source.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 1 to 9B.

1 is an exploded perspective view of a liquid crystal display device including an edge type backlight unit according to an exemplary embodiment of the present invention, and FIG. 2 is a cross-sectional view of the liquid crystal display device shown in FIG. 1. 3 is a view showing the thermal conductivity of the mold compared to the thermal conductivity of the metal. 4A and 4B show a front view and a cross-sectional view of a bottom cover including a lattice structure iron core, respectively.

1 and 2, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal display panel 60, a panel guide 50, a backlight unit 100, a bottom cover 70, and a top case 80. And a light source driver 200.

The liquid crystal display panel 60 includes a thin film transistor array substrate 60a on which a thin film transistor is formed, and a color filter array substrate 60b facing the thin film transistor array substrate 60a and including a black matrix, a color filter, and the like. To display an image. The thin film transistor array substrate 60a and the color filter array substrate 60b are bonded together by a sealant, and a liquid crystal layer is formed between these substrates.

The panel guide 50 supports the liquid crystal display panel 60 as a rectangular mold frame in which glass fibers are mixed in a synthetic resin such as polycarbonate.

The backlight unit 100 includes a light source array 10, a light guide plate 20 that converts light incident from the light source array 10 into planar light, and emits the light to the liquid crystal display panel 60, and a reflection disposed under the light guide plate 20. The sheet 30 is implemented in an edge type including a plurality of optical sheets 40 disposed on the light guide plate 20.

The light source array 10 includes a plurality of LEDs 11 used as light sources, and a metal PCB 12 on which the LEDs 11 are mounted. The light source array 10 may further include a heat sink 13 for dissipating heat generated from the metal PCB 12 to the bottom cover 70. The light source of the light source array 10 may be replaced with at least one lamp of a hot cathode fluorescent lamp (HCFL), a cold cathode fluorescent lamp (CCFL), and an external electrofluorescent lamp (EEFL) instead of the LED 11. .

The light guide plate 20 has its side opposite to the plurality of LEDs 11. The light guide plate 20 converts the light incident from the LED 11 into planar light and emits the light to the plurality of optical sheets 40 disposed thereon. As the light guide plate 20, a material having good refractive index and transmittance, for example, polymethylenemethacrylate (PMA), polycarbonate (PC: polycarbonate), polyethylene (PE: polyethylene), cycloolefin resin (COP) And the like, but are not limited to these materials.

The reflective sheet 30 is disposed under the light guide plate 20, and reflects light traveling in the lower direction of the light guide plate 20 toward the upper direction of the light guide plate 20, that is, toward the liquid crystal display panel 60, to increase light efficiency. .

The optical sheet 40 is disposed between the liquid crystal display panel 60 and the light guide plate 20 to increase the uniformity of light incident through the light guide plate 20 and to increase the luminance by refracting and condensing the light. The optical sheet 40 includes a diffusion sheet 41, a prism sheet 43, and a protective sheet 45. The diffusion sheet 41 diffuses light incident from the light guide plate 20. The prism sheet 43 includes a triangular prism-shaped micro prism, and focuses diffused light incident from the diffusion sheet 41 in a direction perpendicular to the plane of the liquid crystal display panel. The protective sheet 45 protects the prism sheet 43 which is weak to scratches.

The bottom cover 70 accommodates the backlight unit 100. To this end, the bottom cover 70 includes a horizontal portion 71 facing the liquid crystal display panel 60 and a first sidewall portion 72 bent upward from the horizontal portion 71 for fastening the light source array 10. ), A first support portion 73 bent in the horizontal direction from the first side wall portion 72 to support the panel guide 50, and bend downward from the support portion 73 to face the first side wall portion 72. 2 side wall portion 74 is included.

The bottom cover 70 is not formed of a metal material as in the prior art, and insulates heat generated from the light source array 10 and the light source driver 200 to increase the surface temperature of the liquid crystal display panel 60. polycabonate) or the like. As shown in FIG. 3, the thermal conductivity of a mold composed of polycarbonate (polycabonate) is 0.2 to 0.5 kcal / m.hr. ° C., and the thermal conductivity of a metal composed of electrolytic galvanized iron (EGI) (40). ˜45 kcal / m.hr. ° C.). Through the heat transfer property of the mold, the bottom cover 70 may function as a heat source for raising the surface temperature of the liquid crystal display panel 60.

However, since the thermal conductivity of the mold is too low, there is a limit to evenly increasing the surface temperature of the liquid crystal display panel 60 over the entire area. In order to improve the uniformity with respect to the surface temperature of the liquid crystal display panel 60, the bottom cover 70 has at least one heat dissipation member 71A therein so as to dissipate heat into the liquid crystal display panel 60. Increase The heat dissipation member 71A may be implemented with an iron core having a lattice structure as shown in FIGS. 4A and 4B. Since the heat dissipation member 71A disperses the heat of the light source driver 200 that has accumulated due to the mold with low thermal conductivity, the heat dissipation effect of the light source array 10 is enhanced in addition to the above-mentioned uniformity. Furthermore, since the heat dissipation member 71A is implemented with an iron core, the heat dissipation member 71A reinforces the strength of the bottom cover 70, which is a mold, and prevents the bottom cover 70 from being warped due to heat.

The heat dissipation member 71A is built in the horizontal portion 71 of the bottom cover 70. The bottom cover 70 incorporating the heat dissipation member 71A can be obtained by inserting the iron core of the lattice structure together with the mold into the mold for forming the bottom cover 70 and then injection molding.

The top case 80 is made of metal and is fixed to at least one of the panel guide 50 and the bottom cover 70 by a hook or a screw (not shown). The top case 80 surrounds side surfaces of the panel guide 50 and the bottom cover 70. The top case 80 surrounds an edge area (ie, a bezel area) outside the effective display area of the liquid crystal display panel 60.

The light source driver 200 is disposed on the rear surface of the horizontal portion 71 of the bottom cover 70 and electrically connected to the light source array 10. The light source driver 200 generates driving power necessary for driving the LEDs 11.

Figure 5 shows the heat transfer flow by the bottom cover 70 of the mold according to the present invention in comparison with the heat transfer flow by the bottom cover of the conventional metal. 6 shows the effect of temperature increase by the bottom cover 70 of the mold according to the present invention as compared with the case of using the bottom cover of the conventional metal.

Referring to FIG. 5A, since the heat generated by the light source driver is easily dissipated to the outside through the bottom cover in the conventional liquid crystal display including the bottom cover of the metal, heat to contribute to the surface temperature rise of the liquid crystal display panel is obtained. Very difficult to insulate As a result, as shown in FIG. 6A, the surface temperature of the liquid crystal display panel corresponding to the position of the light source driver is relatively low at 34.8 ° C. With this surface temperature, it is not easy to improve the Ton / Toff characteristics of the liquid crystal.

On the other hand, referring to FIG. 5B, since the heat generated from the light source driver 200 is insulated through the bottom cover 70 in the liquid crystal display device of the present invention including the bottom cover 70 of the mold, the bottom cover 70 of FIG. Heat may easily contribute to the surface temperature rise of the liquid crystal display panel 60. As a result, as shown in FIG. 6B, the surface temperature of the liquid crystal display panel 60 corresponding to the position of the light source driver 200 is relatively high at 41.8 ° C. Due to the surface temperature of the liquid crystal display panel 60 which is increased by 7 ° C., the Ton / Toff characteristic of the liquid crystal may be improved.

7 shows the specific gravity by the bottom cover 70 of the mold according to the present invention in comparison with the specific gravity by the bottom cover of the conventional metal. 8 shows the MPRT by the bottom cover 70 of the mold according to the present invention in comparison with the MPRT by the bottom cover of the conventional metal.

Referring to Figure 7, it can be seen that the specific gravity by the bottom cover 70 of the mold according to the present invention is 1.43 g / cm ³ significantly reduced compared to the specific gravity (7.6 g / cm ³ ) by the bottom cover of the conventional metal. have. Through this, the present invention has an effect of reducing the weight of the bottom cover 70 by 2.2 kg compared to the conventional.

Referring to FIG. 8, the bottom cover 70 of the mold according to the present invention raises the surface temperature of the liquid crystal display panel 60 by 7 ° C. compared to the bottom cover of the conventional metal. Through this, the present invention has the effect of reducing the MPRT by about 1.4ms compared to the conventional.

The technical feature of the present invention, in which the bottom cover is formed of a mold and also includes a heat dissipation member inside the bottom cover, is very effective for the above-described edge type backlight unit. This is because in the edge type backlight unit in which the light sources are disposed along the side of the light guide plate, it is difficult to transfer heat generated from the light sources to the surface of the liquid crystal display panel without the configuration of the present invention. However, the technical features of the present invention are not limited to the above-described edge type backlight unit but may be applied to the direct type backlight unit to be described below. In the liquid crystal display device employing the direct type backlight unit, since the light sources are widely distributed under the display panel, the surface temperature of the liquid crystal display panel is higher than that of the edge type described above.

9A illustrates a liquid crystal display including a direct type backlight unit using a lamp as a light source, and FIG. 9B illustrates a liquid crystal display including a direct type backlight unit using an LED as a light source.

The liquid crystal display of FIG. 9A includes a liquid crystal display panel 160, a guide panel 150, a backlight unit, a bottom cover 170 having a heat dissipation member 170A, and a case top 180. The backlight unit includes a lamp 111, a diffuser plate 120 for diffusing light emitted from the lamp 111, a reflective sheet 130 disposed under the lamp 111, and a plurality of diffuser plates disposed on the diffuser plate 120. It is implemented as a direct type including the optical sheet 140.

The bottom cover 170 insulates heat generated from the lamp 111 and the light source driver (not shown, disposed on the bottom of the bottom cover 170) to increase the surface temperature of the liquid crystal display panel 160. polycabonate) or the like. The bottom cover 170 includes at least one heat dissipation member 170A in order to improve the uniformity with respect to the surface temperature of the liquid crystal display panel 160. The heat dissipation member 170A may be implemented with an iron core having a lattice structure as shown in FIGS. 4A and 4B. Since the heat dissipation member 170A disperses the heat of the lamp 111 and the light source driver that are stuck due to the mold with low thermal conductivity, the heat dissipation effect of the lamp 111 is enhanced along with the improvement of the uniformity. Furthermore, since the heat dissipation member 170A is implemented with an iron core, the heat dissipation member 170A reinforces the strength of the bottom cover 170, which is a mold, to prevent distortion of the bottom cover 170 due to heat. The bottom cover 170 made of a mold material having a heat dissipation member 170A increases the surface temperature of the liquid crystal display panel 160 to improve the Ton / Toff characteristics of the liquid crystal, thereby contributing to reducing the MPRT.

The liquid crystal display of FIG. 8B includes a liquid crystal display panel 260, a guide panel 250, a backlight unit, a bottom cover 270 incorporating a heat dissipation member 170A, and a case top 280. The backlight unit is disposed under the LED 211, the metal PCB 212 on which the LED 211 is mounted, the diffuser plate 220 for diffusing light emitted from the LED 211, the LED 211 and the metal PCB 212. The reflective sheet 230 is disposed, it is implemented in a direct type including a plurality of optical sheets 140 disposed on the diffusion plate 220.

The bottom cover 270 insulates heat generated from the LED 211 and the light source driver (not shown, disposed on the bottom of the bottom cover 270) to increase the surface temperature of the liquid crystal display panel 260. polycabonate) or the like. The bottom cover 270 may include at least one heat dissipation member 270A in order to improve the uniformity with respect to the surface temperature of the liquid crystal display panel 260. The heat dissipation member 270A may be implemented with an iron core having a lattice structure as shown in FIGS. 4A and 4B. Since the heat dissipation member 270A disperses the heat of the LED 211 and the light source driver that are stuck due to the mold having low thermal conductivity, the heat dissipation effect of the LED 211 is enhanced along with the improvement of the uniformity. Furthermore, since the heat dissipation member 270A is implemented with an iron core, the heat dissipation member 270A reinforces the strength of the bottom cover 270 that is a mold, thereby preventing distortion of the bottom cover 270 due to heat. The bottom cover 270 made of a mold material having a heat dissipation member 270A increases the surface temperature of the liquid crystal display panel 260 to improve the Ton / Toff characteristics of the liquid crystal, thereby contributing to reducing the MPRT.

As described above, the liquid crystal display device according to the present invention improves the Ton / Toff characteristics of the liquid crystal by increasing the surface temperature of the liquid crystal display panel using a bottom cover made of a mold material without burdening technical difficulties or costs. In this way, the present invention can significantly increase the display quality by reducing the MPRT. In addition, the present invention can greatly contribute to the weight reduction of the liquid crystal display through the bottom cover made of a mold material.

In addition, the liquid crystal display according to the present invention may enhance the panel temperature uniformity and reinforce the bottom cover by embedding the iron core of the lattice structure in the bottom cover.

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.

11,111,211: Light source 12,212: Metal PCB
20: Light guide plate 30,130,230: Reflective sheet
40,140,240: Optical sheet 50,150,250: Panel guide
60,160,260: LCD panel 70,170,270: Bottom cover
71A, 170A, 270A: Heat Dissipation Member 80,180,280: Top Case
100: backlight unit 120,220: diffuser plate
200: light source driver

Claims (8)

A liquid crystal display panel;
A backlight unit radiating light onto the liquid crystal display panel;
A light source driver for driving light sources of the backlight unit; And
The backlight unit is accommodated, and a mold is formed to insulate heat generated from the light sources and the light source driver to increase the surface temperature of the liquid crystal display panel and to provide a uniformity to the surface temperature of the liquid crystal display panel. And a bottom cover incorporating at least one heat dissipation member for improvement. The method of claim 1,
And the heat dissipation member is implemented by an iron core having a lattice structure. The method of claim 2,
The heat dissipation member is embedded in a horizontal portion of the bottom cover facing the liquid crystal display panel;
And the light source driver is disposed on the rear surface of the horizontal portion. The method of claim 2,
And the bottom cover is obtained by inserting the iron core of the lattice structure together with the mold in a mold for forming the bottom cover, followed by injection molding. The method of claim 2,
And the strength of the bottom cover is reinforced by the heat dissipation member. The method of claim 1,
The backlight unit may include a light source array, a light guide plate for converting light incident from the light source array into planar light, and outputting the light to the liquid crystal display panel, an optical sheet disposed between the liquid crystal display panel and the light guide plate, and a reflection disposed under the light guide plate. Liquid crystal display device characterized in that the edge type including a sheet. The method of claim 1,
The backlight unit may include a light source array, a diffuser plate for diffusing light incident from the light source array to the liquid crystal display panel, an optical sheet disposed between the liquid crystal display panel and the diffuser plate, and a reflection disposed below the light source array. Liquid crystal display device characterized in that the direct type including a sheet. The method of claim 1,
The light sources include at least one of a light emitting diode (LED), a hot cathode fluorescent lamp (HCFL), a cold cathode fluorescent lamp (CCFL), and an external electrode fluorescent lamp (EEFL).

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