KR20080018486A - Liquid crystal display - Google Patents

Abstract

A liquid crystal display is provided to distribute heat equally which is transmitted to a liquid crystal display panel to prevent lowering of response speed and defects of a picture due to a temperature difference by areas of the liquid crystal display panel, and diffuse heat transmitted to the liquid crystal display panel to increase a radiation area to prevent deterioration of the liquid crystal display panel. A liquid crystal display includes a liquid crystal display panel(120). A backlight unit(140) is arranged under the liquid crystal display panel. An upper chassis(110) and a lower chassis(150) contain the liquid crystal display panel and the backlight unit. A diffuser plate(145) is installed at the backlight unit to diffuse heat focused on a local area around light sources(142) to a whole area. The upper chassis has an insulator for insulating transmission of heat generated from the light source to the liquid crystal display panel or a radiator for radiating heat generated from the light source to the outside.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY}

1 is a perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

2 is a perspective view illustrating an edge light guide plate of a liquid crystal display according to an exemplary embodiment of the present invention.

3 is a view showing a semi-direct type light guide plate of the liquid crystal display according to the exemplary embodiment of the present invention.

4 is a perspective view illustrating a heat diffusion plate of a liquid crystal display according to an exemplary embodiment of the present invention.

5 is a bottom view illustrating an upper chassis of a liquid crystal display according to an exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

110: upper chassis 120: liquid crystal display panel

130: mold frame 140: backlight unit

141: optical sheet 142: lamp

143: reflector 144: light guide plate

150: lower chassis 160: control PCB

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device capable of realizing high-speed response and more stable operation by eliminating the temperature difference for each region of the liquid crystal display panel.

Liquid crystal display is a display device that realizes an image by controlling the amount of light incident from a light source using the optical anisotropy of liquid crystal molecules and the polarization characteristics of a polarizing film. In recent years, its power consumption is small, and its application range is rapidly expanding.

The liquid crystal display includes a liquid crystal display panel formed by arranging a lower substrate on which a thin film transistor and a pixel electrode are formed, and an upper substrate on which a color filter and a common electrode are formed, and injecting a liquid crystal layer therebetween. And a backlight unit that provides a light source in a lower region of the liquid crystal display panel. In addition, in order to obtain polarization characteristics of light incident from the backlight unit, polarizing films are attached to both surfaces of the liquid crystal display panel.

In the edge type of the backlight unit, a light guide plate is disposed below the liquid crystal display panel, and a light source is disposed on the side of the light guide plate, thereby converting light in the form of a line light source generated from the light source into a surface light source using a light guide plate. The light is dimmed to the back of the liquid crystal display panel. Compared with the direct type, it has excellent luminance uniformity, is advantageous for thinning, and has low power consumption, and is generally used in portable and small and medium sized liquid crystal displays.

In the edge type, part of the heat generated from the light source is transferred to the upper liquid crystal display panel. The heat is concentrated in the corners of the liquid crystal display panel close to both electrode portions of the light source that generate the most heat. This will affect the operating characteristics of.

On the other hand, the response characteristics of the liquid crystal display panel largely depend on the physical properties of the liquid crystal molecules and the polarizing film, the physical properties of the liquid crystal molecules and the polarizing film is sensitively changed to the operating temperature. Therefore, for high speed response, the rotational viscosity and dielectric anisotropy of the liquid crystal molecules should be optimized according to the operating temperature of the liquid crystal display panel, and the polarization characteristics of the polarizing film should also be selected according to the operating temperature of the liquid crystal display panel. As a result of the experiment, it was observed that the response speed of the liquid crystal display panel changes by 2 ms or more according to the operating temperature, which may be the biggest obstacle to the high speed response. For example, in a liquid crystal display panel having a response speed of 20 to 30 ms, an error of about 2 ms is about 10% error range, but an error of about 2 ms is about 40% in a liquid crystal display panel having a response speed of 5 to 6 ms. The margin of error is a very important management factor.

However, in the case of the edge type method described above, since the temperature difference is severe for each region of the liquid crystal display panel, the physical properties of the liquid crystal molecules and the polarizing film are changed differently for each region, and as a result, a difference in response speed occurs for each region, resulting in an overall display quality. There was a problem of deterioration. In addition, there is a problem in that various screen defects caused by deterioration due to excessive heat are accumulated in a specific area of the liquid crystal display panel, particularly in a corner part, for a long period of time.

The present invention is to solve the above problems, by providing a heat diffusion means for diffusing the heat transferred to the local region of the liquid crystal display panel over the entire region, it is possible to make the temperature distribution of the liquid crystal display panel uniform, An object of the present invention is to provide a new liquid crystal display device capable of lowering the operating temperature of the liquid crystal display panel.

According to an exemplary embodiment of the present invention, a liquid crystal display device includes a liquid crystal display panel, a backlight unit disposed under the liquid crystal display panel, an upper chassis and a lower chassis accommodating the liquid crystal display panel and the backlight unit. The backlight unit includes a diffusion means for diffusing heat concentrated in a local area near a light source to the entire area, and blocking the transfer of heat generated from the light source to the liquid crystal display panel in the upper chassis. At least one means for heat dissipation means or heat dissipation means for dissipating heat generated from the light source to the outside is provided.

Preferably, a groove structure is formed on the light guide plate by the diffusion means.

It is preferable that the through structure is formed in the body of the light guide plate by the diffusion means.

Preferably, the diffusion means is provided with a recess in which the light source is installed under the light guide plate.

It is preferable that a heat diffusion layer is formed on at least one surface of the optical sheet.

The backlight unit may further include a heat diffusion plate coupled to one side of the light source and disposed below the light guide plate to diffuse heat transferred from the light source to the entire area of the light guide plate. Such a heat diffusion plate is effective to have a slit structure.

Preferably, a heat diffusion layer is formed on at least one surface of the storage area of the lower chassis.

Preferably, a heat insulation layer formed of a material having a relatively low conductivity is formed under the upper chassis as the heat insulation means.

At least one of a hole, a groove, and a slit may be formed below the upper chassis by the heat dissipation means.

The heat dissipation means may provide a sealed space in the body of the upper chassis, and the sealed space may be filled with a cooling material such as gas or liquid.

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

However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention, and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you. Like reference numerals in the drawings refer to like elements.

1 is a perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the liquid crystal display includes a liquid crystal display panel 120 displaying an image, a backlight unit 140 providing light for displaying an image, the liquid crystal display panel 120 and a backlight unit 140. A control printed circuit board (control PCB) including an upper chassis 110 and a lower chassis 150 for storing various electrical signals and generating various electrical signals required for driving the liquid crystal display panel 120. 160).

A plurality of pixels are formed in the liquid crystal display panel 120 to display an image. Although not shown, the liquid crystal display panel 120 includes an upper substrate and a lower substrate that are opposed to each other, and a liquid crystal layer interposed between the two substrates.

The upper substrate includes a plurality of red (R), green (G), and blue (B) color filters that implement color by coloring light incident in the pixel region, and a plurality of black matrices that block light incident in the non-pixel region. Is a transparent substrate arranged in a lattice structure. A common electrode formed of a transmissive conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO) is formed on an opposite surface of the upper substrate.

The lower substrate is a transparent substrate in which a plurality of thin film transistors (TFTs), which are switching elements, are arranged in a lattice structure. A data line is connected to a source electrode of the thin film transistors, a gate line is connected to a gate electrode, and a pixel electrode formed of a light transmissive conductive material such as ITO or IZO is connected to a drain electrode.

The data PCB 121 and the gate PCB 122 are connected to the liquid crystal display panel 120, and the data PCB 121 is connected to the control PCB 160 through a flexible printed circuit (FPC) 161. It is electrically connected to receive a predetermined signal. The data PCB 121 is electrically connected to a data line formed on the liquid crystal display panel 120 to transmit a gray voltage to each pixel, and the gate PCB 122 is electrically connected to a gate line to each pixel. Transfers the gate on / off voltage and the like. Of course, the data PCB 121 and the gate PCB 122 may be integrated into one.

A polarizing film (not shown) is attached to both sides of the liquid crystal display panel 120 of the present embodiment, and heat is concentrated on a local area of the liquid crystal display panel 120 on one side or both sides of the polarizing film (not shown). It is preferable that a heat diffusion layer (not shown) formed by applying a material having excellent light transmissivity and thermal conductivity, for example, ITO or IZO, as a diffusion means for diffusing the entire region.

The backlight unit 140 includes a lamp 142, a reflector 143, a light guide plate 144 disposed on the side of the lamp 142, an optical sheet 141 disposed on the light guide plate 144, and a light guide plate 144. It includes a heat diffusion plate 145 disposed at the bottom of the.

It is effective to use a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp (EEFL) as the lamp 142.

The reflector 143 reflects light emitted radially from the lamp 142 in one direction to maximize light utilization efficiency.

The optical sheet 141 is disposed on the front surface of the light guide plate 144 to uniform the luminance distribution of the light emitted upward. The optical sheet 141 may include a diffusion sheet 141A, a first prism sheet 141B, and a second prism sheet 141C from below. Here, the diffusion sheet 141A has a scattering pattern to scatter and diffuse light incident from the light guide plate 144 in an upward direction, and the first and second prism sheets 141B and 141C respectively have upper surfaces. It has a prism pattern formed in the direction intersecting with each other to serve to condense the light emitted in the upper direction by vertically changing the light incident obliquely from the light incident from the diffusion sheet (141A).

The optical sheet 141 is a diffusion means for diffusing heat concentrated from the lamp 142 and concentrated in the local area to the entire area, and a material having excellent light transmissivity and thermal conductivity, for example, ITO or IZO, is coated on one surface thereof. The formed heat diffusion layers 141a, 141b, and 141c are provided. Of course, the heat diffusion layers 141a, 141b, and 141c may be provided only in any one of the diffusion sheet 141A, the first prism sheet 141B, and the second prism sheet 141C constituting the optical sheet 141. It may be provided in duplicate.

The light guide plate 144 converts light having an optical distribution in the form of a line light source generated by the lamp 142 into light having an optical distribution in the form of a surface light source. As the light guide plate 144, a polymer-based wedge type plate or a parallel flat plate may be used.

2 is a perspective view illustrating an edge light guide plate used in a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the light guide plate 144 is a diffusion means for diffusing heat generated from a lamp 142 installed at a side surface of the light guide plate 144 into an entire region, and a through structure 144a may be formed therein, or The recess structure 144b may be formed on the upper portion thereof.

The through structure 144a may be formed by penetrating the body region of the light guide plate 144 from one side to the other side, and the groove structure 144b may be curved such as a triangle, a hemispherical shape, a lens shape, and the like on the upper surface of the light guide plate 144. It can be formed by processing to have a true cross-sectional structure.

The through structure 144a and the concave structure 144b provide a ventilation path through which air can be communicated smoothly so that heat concentrated in the localized area can be quickly and uniformly spread throughout the entire area. Accordingly, the through structures 144a and the concave structures 144b are arranged such that both inlets of the ventilation paths provided by them are directed toward the lamp 142 coupled to the side surface of the light guide plate 144 so that heat is rapidly spread. Preferably, the through-hole structure 144a and the recess structure 144b are formed in plural so that the heat is uniformly distributed so that the ventilation paths provided by them are arranged to maintain a constant separation distance.

3 is a view showing a semi-direct type light guide plate used in the liquid crystal display according to the exemplary embodiment of the present invention, (a) is a perspective view of the semi-direct type light guide plate, and (b) is a side view of the semi-direct type light guide plate.

Referring to FIG. 3, in the liquid crystal display, as described above, instead of the edge-shaped light guide plate 144 formed in a flat shape, the semi-direct type light guide plate on which the receiving groove 210 is formed may be mounted at the lower portion thereof. 200 may be used.

In the lower portion of the lower direct light guide plate 200, a receiving groove 210 is formed to be recessed inwardly from a surface thereof according to a position where the lamp 142 is disposed, thereby providing a predetermined space in which the lamp 142 may be mounted. do. The accommodating groove 210 is formed of a relatively flat plane portion and a sidewall portion inclined outward, and is formed to correspond to the position, shape, and number of lamps 142 used.

When the semi-direct light guide plate 200 is used, a part of the light generated by the lamp 142 is incident on the planar portion and the sidewall portion of the receiving groove 210, and the light incident on the planar portion is along a direct light path. The light incident on the sidewall portion proceeds along an edge-type optical path and eventually enters the upper liquid crystal display panel 120.

When the semi-low light guide plate 200 is used, the installation positions of the lamps 142 may be evenly distributed, so that heat generated from the lamps 142 is uniformly transmitted over the entire area of the liquid crystal display panel 220. There is.

4 is a perspective view illustrating a heat diffusion plate used in a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the heat diffusion plate 145 may be manufactured by processing a material having excellent light transmittance and thermal conductivity, for example, ITO or IZO in a slit form. In the present exemplary embodiment, the heat diffusion plate 145 is manufactured in the form of a slit, but the present invention is not limited thereto. For example, the heat diffusion plate 145 may be manufactured in the form of a slit. Of course it can be produced as. An end of the heat diffusion plate 145 is preferably coupled to one side of the lamp 142 or the reflector 143 to diffuse the heat generated from the lamp 142 to the entire area.

On the other hand, in the backlight unit of the present embodiment, the lamp 142 is disposed on both sides of the light guide plate 144, but is not limited thereto. The lamp 142 may be disposed only on one side of the light guide plate 144.

In the control PCB 160, a driving circuit such as a timing control circuit, a voltage drop circuit, an AD converting circuit, and the like are integrated and mounted on a substrate to drive an image signal and supply power applied from the outside suitable for operation of the liquid crystal display panel 120. The signal is converted into a driving power source and transmitted to the data PCB 121 and the gate PCB 122. Various electrical signals generated by the control PCB 160 are transmitted to the data PCB 121 through the FPC 161. Of course, the FPC 161 may be connected to both sides of the gate PCB 121 and the data PCB 122.

In the storage space provided by the combination of the upper chassis 110 and the lower chassis 150, a mold frame 13 which protects an edge of the liquid crystal display panel 120 which is vulnerable to impact and fixes the mounting position of the optical sheet 141. ) Is accepted. Of course, the mold frame 13 can be omitted if necessary.

The upper chassis 110 is formed in a rectangular frame shape including a planar portion in which an opening region for exposing the pixel region of the liquid crystal display panel 120 to the outside and a sidewall portion extending from an edge of the planar portion.

A portion of the heat generated by the backlight unit 140 is transferred to the lower chassis 150, and the liquid crystal display panel disposed under the upper chassis 110 through the upper chassis 110 coupled to the lower chassis 150 ( 120). As a result, more heat is accumulated at the edges of the liquid crystal display panel 120 in contact with the upper chassis 110, particularly at corners close to both electrode portions of the lamp 142 having high heat generation. Uneven temperature distribution of the panel 120 may result in a decrease in response speed and light leakage. Therefore, the lower or body of the upper chassis 110 according to the present embodiment is provided with at least one means of heat insulation means and heat dissipation means for blocking heat transfer to the bottom and facilitate heat dissipation to the outside. Preferred, but will be described as follows.

5 is a bottom view illustrating an upper chassis used in the liquid crystal display according to the exemplary embodiment of the present invention.

As shown in FIG. 5A, the heat insulating means may be formed by coating or bonding a material 111 having a relatively low thermal conductivity, for example, plastic or rubber, to the lower portion of the upper chassis 110.

The heat dissipation means may be configured by forming a hole (112) in the body of the upper chassis 110, as shown in Figure 5 (b). Of course, the hole 112 may be replaced with a groove or a slit, and the hole 112, the groove and the slit may reduce the contact area between the upper chassis 110 and the liquid crystal display panel 120, and thus the upper chassis 110. ) To prevent heat transfer to the liquid crystal display panel 120 and to increase the contact area between the upper chassis 110 and the outside air to help heat dissipation to the outside.

In addition, the heat dissipation means, as shown in Fig. 5 (c), to provide a sealed space 113 in the body of the upper chassis 110 and to fill the cooling material 114, such as gas or liquid to be configured there. Can be. The cooling material 114 absorbs some heat from the upper chassis 110 to prevent heat transfer from the upper chassis 110 to the liquid crystal display panel 120.

The lower chassis 150 includes a flat bottom surface and sidewall portions extending from edges of the bottom surface. The bottom and sidewalls of the lower chassis 150 may further include a reflective layer (not shown) formed of a material having excellent light reflectivity, such as silver (Ag) and aluminum (Al), to increase light utilization. In order to diffuse the heat generated from the lamp 142 to the entire region, a heat diffusion layer (not shown) formed by applying a material having excellent translucency and thermal conductivity, for example, ITO or IZO, may be formed.

As described above, the liquid crystal display according to the present invention may be used to insulate, diffuse, and distribute heat to various components, such as the liquid crystal display panel 120, the backlight unit 140, the upper chassis 110, and the lower chassis 150. Means are provided, the means can be applied to all of the above-described components, but of course it can be selectively applied only to some components. In addition, the heat transmitted to the liquid crystal display panel 120 by the means is not concentrated in the local region but uniformly distributed over the entire region, and as the heat is uniformly spread, the heat dissipation area is increased so that the liquid crystal display panel 120 is increased. Will lower the operating temperature.

As described above, the above embodiments are disclosed for purposes of illustration, and those skilled in the art will appreciate that various modifications, improvements, substitutions, and additions may be made without departing from the spirit of the present invention. Accordingly, the technical scope of the present invention is defined by the appended claims.

As described above, in the present invention, since the heat transmitted to the liquid crystal display panel is uniformly distributed over the entire region, it is possible to solve a decrease in response speed and various screen defects caused by the temperature difference for each region of the liquid crystal display panel.

In addition, according to the present invention, as the heat transmitted to the liquid crystal display panel is uniformly diffused to the entire region, the heat dissipation area is increased to lower the operating temperature of the liquid crystal display panel. Therefore, deterioration of the liquid crystal display panel can be prevented, so that stable operation is possible.

Claims (14)

A liquid crystal display panel, A backlight unit disposed under the liquid crystal display panel; An upper chassis and a lower chassis accommodating the liquid crystal display panel and the backlight unit; The backlight unit is provided with diffusion means for diffusing heat concentrated in the local area near the light source to the entire area, The upper chassis is provided with at least one of heat insulating means for blocking heat generated from the light source from being transmitted to the liquid crystal display panel or heat radiating means for radiating heat generated from the light source to the outside. Liquid crystal display. The method according to claim 1, And a heat diffusion layer formed on at least one surface of the liquid crystal display panel. The method according to claim 1, The backlight unit, A light source for generating light, A light guide plate which makes the brightness of light uniform; An optical sheet disposed on the light guide plate; And at least one of the light guide plate and the optical sheet is provided with the diffusion means. The method according to claim 3, And a groove structure is formed on the light guide plate by the diffusion means. The method according to claim 3, And a through structure is formed in the body of the light guide plate by the diffusion means. The method according to claim 3, And a recess, in which the light source is installed, is formed under the light guide plate by the diffusion means. The method according to claim 3, And a heat diffusion layer formed on at least one surface of the optical sheet. The method according to claim 3, And a heat diffusion plate coupled to one side of the light source and disposed below the light guide plate to diffuse heat transferred from the light source to the entire region of the light guide plate. The method according to claim 8, And the heat diffusion plate has a slit structure. The method according to claim 1, And a heat diffusion layer formed on at least one surface of an accommodating area of the lower chassis. The method according to any one of claims 2, 7, and 10, The heat diffusion layer comprises at least one of ITO and IZO. The method according to claim 1, And a heat insulating layer formed of a material having a relatively low conductivity is formed under the upper chassis by the heat insulating means. The method according to claim 1, And at least one of a hole, a groove, and a slit is formed below the upper chassis by the heat dissipation means. The method according to claim 1, And a sealed space is provided in the body of the upper chassis by the heat dissipation means, and a cooling material such as gas or liquid is filled in the sealed space.

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