KR101158599B1 - Backlight unit and liquid crystal display having the same - Google Patents

Abstract

The present invention relates to a backlight unit of a liquid crystal display device, wherein the liquid crystal display device having the backlight unit of the liquid crystal display device includes: a light emitting element array unit comprising a plurality of light emitting elements; A light emitting element support on which the light emitting element array is disposed; A lower cover having an opening for inserting a lower end of the light emitting device support to be exposed to the outside; And a heat sink coupled in direct contact with the light emitting device support.

Light guide plate, LED, heat sink, bottom cover

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY HAVING THE SAME}

1 is a cross-sectional view of a light emitting device coupled to a backlight unit of a liquid crystal display according to the prior art.

2 is an exploded cross-sectional view of a light emitting device unit, a lower cover, and a heat sink in a backlight unit of a liquid crystal display device according to the prior art;

3 is a cross-sectional view of the light emitting device coupled to the backlight unit of the liquid crystal display according to the present invention.

4 is an exploded cross-sectional view of a light emitting device unit, a lower cover, and a heat sink in a backlight unit of a liquid crystal display according to the present invention;

-Explanation of symbols for the main parts of the drawings-

111 light emitting element 113 light emitting element support

115: lower cover 115a: lower portion

117: fastening means (screw) 119: heat sink

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit of a liquid crystal display device, and more particularly to a liquid crystal display capable of dissipating heat generated from a light emitting device (LED) to a heat sink smoothly without passing through a lower cover from a light emitting device support. It relates to a backlight unit of the device.

Among the many flat panel displays developed to date, liquid crystal displays are widely used in a wide variety of applications ranging from laptops, monitors, televisions, spacecraft, and aircraft.

There are three main types of liquid crystal displays, a liquid crystal display panel, a driving circuit unit, and a backlight unit.

Here, the liquid crystal display panel is bonded to the substrate on which the TFT array is formed and the substrate on which the color filter is formed to be maintained at a predetermined interval, and a liquid crystal layer is formed by injecting liquid crystal between the two substrates. Polarizers are attached to the outside of the two substrates, respectively.

In addition, the driving circuit unit includes various circuit elements and a printed circuit board (PCB).

The backlight unit includes a light emitting lamp, various sheets, a support mold, and the like.

In the liquid crystal display device composed of the components as described above, the liquid crystal liquid crystal display panel is responsible for displaying an image by adjusting the amount of transmitted light, and the driving circuit unit is configured to receive various signals transmitted from the driving system. It applies a signal to the liquid crystal display panel and controls the signal. In addition, the backlight unit is used as a dimming device for evenly irradiating light on the entire liquid crystal display panel. The mounting of the backlight is inefficient in terms of thickness, weight, and power consumption, and much research is still being conducted.

Since the display by the liquid crystal display panel itself is non-luminescent, it cannot be used where there is no light. Therefore, the backlight for uniformly irradiating the display surface for the purpose of making it possible to use in a dark place to compensate for this disadvantage.

Since the backlight is a light source of the liquid crystal display device, it is required to emit the brightest light with the minimum power, and maintains the same fluorescent light as a line to the surface brightness by maintaining the same brightness to every corner of the liquid crystal display device.

Such a backlight is a direct type in which the light emitting lamp irradiates light directly from the rear side of the liquid crystal display device to the front side according to the position of the light emitting lamp, and the light is located on the side of the light guide plate. Side type (Side Type) and part of the side type to face the front while passing through the light emitting lamp is located on only one side by using the inclined light guide plate, half light from one side passes through the inclined light guide plate It can be classified into an edge type that faces.

The side backlight may include a light emitting lamp for emitting light, a reflective sheet for reducing light loss, a lamp cover surrounding the light emitting lamp, and light exiting to the rear surface of the light guide plate in the direction of the light guide plate. The reflection sheet and the light toward the front have to be changed in the medium so that dots are formed on the bottom surface of the light guide plate through dot screen printing process, and small glass beads are included in the dots. Light is scattered on the glass bead surface, and the light guide plate through which the scattered light passes, and the light scattered through the printed light guide plate directly enters the eye, thus minimizing the shape of the pattern printed on the light guide plate. After passing through the diffusion sheet and the diffusion sheet, the luminance is rapidly decreased to focus the luminance again. It consists of a prism sheet to increase the brightness, a protection sheet to prevent external impact or contamination from foreign substances, and a mold frame that finally supports the above components. do.

The side-type backlight configured as described above has a problem in that the light is distributed to the entire surface by using the light guide plate, and the luminance is low because the light emitting lamp is installed outside the light guide plate and light passes through the light guide plate.

Recently, a light emitting device (LED) is used as a light source, and the backlight unit of the conventional liquid crystal display device employing the light emitting device will be described in detail with reference to FIGS. 1 and 2 as follows.

1 is a cross-sectional view of a light emitting device coupled to a backlight unit of a liquid crystal display according to the related art.

2 is an exploded cross-sectional view of a light emitting device unit, a lower cover, and a heat sink in a backlight unit of a liquid crystal display according to the related art.

In general, when the light emitting device (LED) is applied as a light source of the backlight unit, when power is applied to the light emitting device (LED), about 20% is emitted in the vertical direction, and about 80% in the horizontal direction. Outgoing.

In addition, referring to FIG. 1, in the backlight unit structure according to the related art, a plurality of light emitting devices 11 constituting a light emitting array are coupled to a metal core PCB (MCPCB) 13. The support 13 is coupled to the lower cover 15 by fastening means 17.

In addition, a heat sink 19 is coupled to a lower surface of the lower cover 15 by fastening means (not shown). Here, the heat sink 19 functions to dissipate heat generated from the light emitting element (LED) 11 transferred to the lower cover 15 to the outside.

Although not shown in the drawings, a light guide plate (not shown) is disposed above the plurality of light emitting elements 11 and spaced apart from the plurality of light emitting elements 11, and corresponds to each of the light emitting array parts including the plurality of light emitting elements 11. A reflector (not shown) made of a prism structure or a reflective material is disposed on the lower surface of the light guide plate (not shown). Here, the reflector (not shown) is used for color mixing as well as suppressing light emission in the vertical direction.

In addition, a diffusion plate (not shown) and an optical sheet layer (not shown) are disposed on the light guide plate (not shown), and a liquid crystal display panel (not shown) is disposed on the light guide plate (not shown).

 According to the backlight unit of the liquid crystal display device according to the related art configured as described above, power is applied to the plurality of light emitting elements 11 so that light is emitted from the light emitting elements 11 in the horizontal direction and the vertical direction. The emitted light is reflected by a reflector (not shown) disposed on the lower surface of the light guide plate and guided in the horizontal direction so that the light is uniformly distributed on the entire back surface of the backlight.

However, according to the heat dissipation structure of the backlight unit of the liquid crystal display device according to the related art, which is constituted as described above, separate light emitting element supports and the lower cover are coupled by fastening means, and an air gap between them. Will exist. Therefore, since the air gap is present, heat generated in the light emitting device is not transferred to the lower cover, but a part of the heat is transferred to the inside of the backlight unit through the air gap, thereby preventing effective heat dissipation. In particular, since the thermal conductivity of air is significantly lower than that of metal, effective heat dissipation is difficult.

In particular, since the light emitting device (LED) generates a higher amount of heat than the light efficiency, when the temperature rise due to high heat generation occurs, the efficiency of the light emitting device drops sharply, and color shift occurs. As the structure is deformed, it greatly affects the reliability of the light emitting device (LED).

Accordingly, the present invention has been made to solve the above problems according to the prior art, by lowering the thermal resistance of the lower cover to increase the heat dissipation efficiency to increase the light efficiency of the light emitting device degraded by the temperature and to ensure the reliability of the light emitting device An object of the present invention is to provide a backlight unit of a liquid crystal display device and a liquid crystal display device having the same.

In order to achieve the above object, a backlight unit of a liquid crystal display device includes: a light emitting device array unit including a plurality of light emitting devices; A light emitting element support on which the light emitting element array is disposed; A lower cover having an opening for inserting a lower end of the light emitting device support to be exposed to the outside; And a heat sink coupled in direct contact with the light emitting device support.

In addition, a liquid crystal display device having a backlight unit according to the present invention includes a liquid crystal display panel; And a backlight unit disposed under the liquid crystal display panel, wherein the backlight unit comprises: a light emitting element array unit comprising a plurality of light emitting elements; A light emitting element support on which the light emitting element array is disposed; A lower cover having an opening for inserting a lower end of the light emitting device support to be exposed to the outside; And a heat sink coupled in direct contact with the light emitting device support.

Hereinafter, a backlight unit of a liquid crystal display device and a liquid crystal display device having the same according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a cross-sectional view of the light emitting device coupled to the backlight unit according to the present invention.

4 is an exploded cross-sectional view of a light emitting device unit, a lower cover, and a heat sink in the backlight unit according to the present invention.

3 and 4, in the backlight unit of the liquid crystal display according to the present invention, a plurality of light emitting elements 111 constituting one light emitting array is provided on a metal core PCB (MCPCB) 113. Are combined.

In addition, an opening 115a is formed on a lower surface of the lower cover 115 so that the lower end 113a of the light emitting device support 113 to which the plurality of light emitting devices 111 are coupled is inserted through and exposed to the outside.

A lower surface of the lower cover 115 is provided with a heat sink 119 that is directly coupled to the light emitting device support 113 exposed to the outside through the opening 115a. Here, the heat sink 119 functions to dissipate heat generated from the light emitting device (LED) 111 transferred to the lower cover 115 to the outside.

In addition, the light emitting device support 113, the lower cover 115 and the heat sink 119 is fastened to each other by a fastening screw 117 or other fastening means.

Although not shown in the drawings, a light guide plate (not shown) is disposed above the plurality of light emitting devices 111 and spaced apart from each other by a predetermined distance, and corresponds to each of the light emitting array parts including the plurality of light emitting devices 111. A reflector (not shown) made of a prism structure or a reflective material is disposed on the lower surface of the light guide plate (not shown). Here, the reflector (not shown) is used for color mixing as well as suppressing light emission in the vertical direction.

In addition, a diffusion plate (not shown) and an optical sheet layer (not shown) are disposed on the light guide plate (not shown), and a liquid crystal display panel (not shown) is disposed on the light guide plate (not shown).

 According to the backlight unit of the liquid crystal display device according to the present invention configured as described above, the power is applied to the plurality of light emitting elements 111 to emit light in the horizontal direction and the vertical direction from the light emitting element 111 in the horizontal direction The emitted light is reflected by a reflector (not shown) disposed on the lower surface of the light guide plate and guided in the horizontal direction so that the light is uniformly distributed on the entire back surface of the backlight.

In addition, the light emitting device support 113 in which the plurality of light emitting devices 111 are disposed is directly contacted and coupled to the heat sink 119 through the opening 115a formed in the lower cover 115. Heat generated from the light emitting elements 111 is effectively radiated to the outside through the heat sink 119 in direct contact with the light emitting element support 113.

In this way, since the heat generated from the plurality of light emitting elements 111 is effectively radiated to the outside, the temperature rise in the backlight unit is suppressed to prevent a sudden decrease in the efficiency of the light emitting elements.

Therefore, since the efficiency of the light emitting device can be prevented from being drastically reduced, color shift phenomenon can be prevented from occurring, and the mold structure due to heat generation can be prevented in advance.

Meanwhile, a liquid crystal display device having a backlight unit having a heat dissipation structure according to the present invention configured as described above will be described with reference to FIGS. 3 and 4.

Although not shown in the drawings, the LCD according to the present invention includes a liquid crystal display panel in which pixels are arranged in a matrix form, and a backlight unit disposed on a lower surface of the liquid crystal display panel.

The liquid crystal display panel may include a thin film transistor array substrate (not shown) and a color filter substrate (not shown), and a color filter substrate (not shown) and a thin film transistor array, which are bonded to face each other to maintain a uniform cell gap. It is composed of a liquid crystal layer (not shown) formed at a spaced interval of the substrate (not shown).

In addition, a common electrode (not shown) and a pixel electrode (not shown) are formed on the liquid crystal display panel where the thin film transistor array substrate and the color filter substrate are joined to apply an electric field to the liquid crystal layer (not shown).

Therefore, when the voltage of the data signal applied to the pixel electrode is controlled while the voltage is applied to the common electrode, the liquid crystal of the liquid crystal layer rotates by dielectric anisotropy according to the electric field between the common electrode and the pixel electrode. For example, characters or images are displayed by transmitting or blocking light for each pixel.

In addition, in order to control the voltage of the data signal applied to the pixel electrode for each pixel, a switching element such as a thin film transistor is separately provided in the pixels.

Meanwhile, referring to FIGS. 3 and 4, the backlight unit includes a lower cover 115, a plurality of light emitting elements 111 disposed in the lower cover 115 to emit light in horizontal and vertical directions; It is configured to include a light guide plate (not shown) disposed on the plurality of light emitting elements (111). Here, the plurality of light emitting devices 111 constitutes one light emitting device array unit.

In addition, the light emitting device support 1130 in which the light emitting device array unit including the plurality of light emitting devices 111 is provided is in direct contact with the heat sink 119 through the opening 115a formed in the lower cover 115. In this case, heat generated from the plurality of light emitting elements 111 is effectively radiated to the outside through the heat sink 119 in direct contact with the light emitting element support 113.

Although not shown in the drawing, the liquid crystal display panel and the backlight unit are surrounded by the guide panel, and the side surfaces of the wrapped liquid crystal display panel and the backlight unit are supported by the lower cover.

In addition, the upper edge portion of the liquid crystal display panel is fixed by the top case, the top case is coupled to the guide panel, the guide panel is coupled to the lower cover to complete the liquid crystal display device.

As described above, the backlight unit of the liquid crystal display device and the liquid crystal display device having the same according to the present invention have the following effects.

According to the heat dissipation structure of the backlight unit according to the present invention, the light emitting device support on which the plurality of light emitting devices are disposed is coupled to the heat sink through direct contact with the heat sink through the opening formed in the lower cover, thereby providing the existing light emitting device support and the lower cover. Since the air gap is eliminated, heat generated from the plurality of light emitting devices is effectively radiated to the outside through a heat sink in direct contact with the light emitting device support.

In this way, since the heat generated from the plurality of light emitting devices is effectively radiated to the outside, the temperature rise in the backlight unit is suppressed to prevent a rapid decrease in the efficiency of the light emitting devices.

Therefore, since the efficiency of the light emitting device can be prevented from being drastically reduced, color shift phenomenon can be prevented from occurring, and the mold structure due to heat generation can be prevented in advance.

Therefore, the light emitting device support is passed through the opening of the lower cover to lower the thermal resistance of the lower cover to increase the heat dissipation efficiency, thereby increasing the light efficiency of the light emitting device (LED) degraded by the temperature and ensuring the reliability of the light emitting device. Can be.

On the other hand, while described above with reference to a preferred embodiment of the present invention, those skilled in the art various modifications of the present invention without departing from the spirit and scope of the invention described in the claims below And can be changed.

Claims (6)

A light emitting element array unit comprising a plurality of light emitting elements; A light emitting element support on which the light emitting element array is disposed; A lower cover having an opening for inserting a lower end of the light emitting device support to be exposed to the outside; And And a heat sink disposed on a lower surface of the lower cover, the heat sink being in direct contact with the light emitting device support exposed to the outside through the opening. The backlight unit of claim 1, wherein the light emitting device support, the lower cover, and the heat sink are integrally coupled by a screw or other fastening means. The backlight unit of claim 1, wherein a light guide plate is provided above the light emitting element array unit. A liquid crystal display panel; And And a backlight unit disposed under the liquid crystal display panel. The backlight unit A light emitting element array unit comprising a plurality of light emitting elements; A light emitting element support on which the light emitting element array is disposed; A lower cover having an opening for inserting a lower end of the light emitting device support to be exposed to the outside; And And a heat sink disposed on a lower surface of the lower cover, the heat sink being in direct contact with the light emitting device support exposed to the outside through the opening. The liquid crystal display of claim 4, wherein the light emitting device support, the lower cover, and the heat sink are integrally coupled by a screw or other fastening means. 5. The liquid crystal display device according to claim 4, wherein a light guide plate is provided above the light emitting element array portion.

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