KR101870983B1 - Backlight unit and liquid crystal display device having the same - Google Patents

Abstract

The present invention relates to a liquid crystal display (LCD) device having a backlight unit. A light source unit disposed below the liquid crystal panel and providing light to the liquid crystal panel; A light guide plate arranged to be spaced apart from the light source unit and to transmit light emitted from the light source unit in the upward direction; A plurality of optical sheets arranged on the light guide plate; A guide panel disposed above the light source unit and supporting the liquid crystal panel; And a lower cover in which the light source unit and the light guide plate are accommodated and a rigid reinforcing structure is provided on the lower surface.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THE SAME [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a backlight unit and a liquid crystal display device having the same.

Of the many flat panel display devices developed so far, liquid crystal display devices are widely used in various fields ranging from notebooks, monitors, televisions, spacecrafts and aircrafts.

Liquid crystal display devices applied to these various application fields are roughly divided into a liquid crystal panel, a driving circuit portion, and a backlight unit.

Here, the liquid crystal panel functions to display an image by adjusting the amount of transmitted light, and the driving circuit unit applies a signal to the liquid crystal panel to control various signals transmitted from the driving system to control the signals. do.

In addition, the backlight unit is used as a light control apparatus for uniformly irradiating light to the entire liquid crystal panel. The mounting of the backlight is inefficient in terms of thickness, weight, and power consumption, and much research is still being conducted.

Since such a liquid crystal display device is not a self-luminous display device, a light source such as a backlight is required.

There are two types of backlight units for liquid crystal display devices, namely direct-type and edge-type.

An edge type backlight unit is provided with a fluorescent lamp on the outer surface of a flat plate. Light is incident on the entire surface of the liquid crystal panel using a transparent light guide plate from a fluorescent lamp. On the other hand, since the backlight unit of the edge type uses a light guide plate, the thickness of the backlight unit is relatively small.

A direct-type backlight unit is a method of directly illuminating the entire surface of a liquid crystal panel by placing a light source on the back surface of the liquid crystal panel. It is possible to increase the brightness by arranging a plurality of light sources in comparison with the edge type, There are advantages.

However, in the case of the edge type, there is a disadvantage in that the light weight is heavier than the direct-type backlight unit due to the use of the light guide plate, and the light efficiency of the backlight unit is lowered due to the absorption and disappearance of light from the light guide plate. On the other hand, in the direct type, the light efficiency is better than the edge type, but it is pointed out that the high power consumption and heat generation due to the use of a large number of lamps are disadvantageous.

In addition, since the light guide plate does not exist between the lamp and the optical sheet, the direct type has a certain distance between the lamp and the optical lamp, thereby increasing the thickness of the backlight unit.

Such liquid crystal display devices include a light source such as a backlight, optical sheets for improving light efficiency when the light from the light source travels toward the liquid crystal panel, and light guides for guiding light from the light source toward the liquid crystal display panel. And cases for supporting and fixing them are needed.

To this end, the liquid crystal display devices are assembled to the case by stacking the light source, the optical sheet, the light guide plate, and the like on the back surface of the liquid crystal panel.

Among these direct-type and edge-type backlight units, a liquid crystal display device having a conventional edge-type backlight unit will be described with reference to FIGS.

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

2 is a plan view showing an outer bottom surface of a lower cover in a liquid crystal display device having a backlight unit according to the related art.

3 is a cross-sectional view of a lower cover in a liquid crystal display device having a backlight unit according to the related art.

4 is a cross-sectional view schematically showing a bent state of a lower cover in a liquid crystal display device having a backlight unit according to the related art.

FIG. 5 is a cross-sectional view schematically showing a twisted state of a lower cover in a liquid crystal display device having a backlight unit according to the related art.

1 and 2, a liquid crystal display device having a backlight unit according to the related art includes a liquid crystal panel 16 on which an image is implemented; A guide panel 19 supporting an edge of the liquid crystal panel 16, a light source 10 provided below the liquid crystal panel 16, A light guide plate 25 for advancing the light incident from the light guide plate 25 toward the liquid crystal panel 16, a reflection sheet 23 disposed on the back surface of the light guide plate 25, and a plurality of optical sheets 25 stacked on the light guide plate 25, A light source housing 12 surrounding the light source unit 10 and a lower cover 21 accommodating the light source unit 10 and the reflective sheet 23 and the light guide plate 25 and the optical sheet 11, And a backlight unit (not shown).

The liquid crystal panel 16 includes a color filter substrate 13 and an array substrate 15 and a liquid crystal layer (not shown) formed therebetween. An upper polarizing sheet 14a is formed on the color filter substrate 13, And a lower polarizing sheet 14b is attached to the rear surface of the array substrate 15. [

The top case 17 is fastened to the upper edge of the liquid crystal panel 16 and the guide panel 19 to be wrapped.

The light source unit 10 includes an LED element 10a and a substrate 10b on which the LED element 10a is mounted.

The plurality of optical sheets 11 include a lower diffusion sheet 14a for diffusing the light emitted from the light guide plate 25 to the entire region and a diffusion sheet 14b for diffusing the progress angle of the light diffused by the diffusion sheet 14a, Two prism sheets 14b and 14c perpendicular to the panel 16 and an upper diffusion sheet 14d for diffusing the light passed through the two prism sheets 14b and 14c.

The reflective sheet 23 functions to reduce light loss by reflecting light incident through the back surface of the light guide plate 25 toward the light guide plate 25.

The light source 10, the reflection sheet 23, the light guide plate 25, and the optical sheet 11 are accommodated in the lower cover 21, and an FPCB (Flexible Printed Circuit Board) And the center of the outer surface is connected to a buyer system.

However, in order to solve the problem of heat dissipation caused by applying an LED (Light Emitting Diode) as a light source, the material of the lower cover is changed to aluminum (Al). Many problems arise.

Particularly, in order to maintain the lifetime of the LED while using the LED as the light source, the temperature control is the most important factor. In order to lower the temperature, the material of the lower cover is used as aluminum (Al). Aluminum has better thermal conductivity than steel material but has a stiff part. Therefore, in the case of the conventional lower cover 21 made of aluminum, since the mechanical strength is weak against the force acting in the vertical direction, the ripple is generated due to interference with the buyer system.

2 and 3, since the conventional lower cover 21 does not have a structure for reinforcing the additional strength on the outer surface as shown in Figs. 2 and 3, in the press working, as shown in Figs. 4 and 5, Side effects such as warpage and twist phenomenon occur.

Since the conventional lower cover 21 is in the form of a flat plate, the force acting in the vertical direction on the flat plate is mechanically weakened, and a phenomenon of stagnation due to its own weight occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a lower cover having a rigid reinforcing structure integrally protruded to improve rigidity of a lower cover, And a liquid crystal display device having the backlight unit.

According to an aspect of the present invention, there is provided a backlight unit including: a light source unit for providing light; A light guide plate arranged to be spaced apart from the light source unit and to transmit light emitted from the light source unit in the upward direction; A plurality of optical sheets arranged on the light guide plate; A guide panel disposed above the light source unit and supporting the liquid crystal panel; And a lower cover in which the light source unit and the light guide plate are accommodated and a rigid reinforcing structure is provided on a lower surface thereof.

According to an aspect of the present invention, there is provided a liquid crystal display device including a backlight unit. A light source unit disposed below the liquid crystal panel and providing light to the liquid crystal panel; A light guide plate arranged to be spaced apart from the light source unit and to transmit light emitted from the light source unit in the upward direction; A plurality of optical sheets arranged on the light guide plate; A guide panel disposed above the light source unit and supporting the liquid crystal panel; And a lower cover in which the light source unit and the light guide plate are accommodated and a rigid reinforcing structure is provided on a lower surface thereof.

The backlight unit and the liquid crystal display device having the same according to the present invention have the following effects.

According to the backlight unit and the liquid crystal display device having the same according to the present invention, the first rigid reinforcing structure in which both side ends are bent on the lower cover and the second rigid reinforcing structure in the form of a bulge are integrally protruded, So that the amount of deformation deformed by the force can be minimized to prevent interference.

In addition, according to the backlight unit and the liquid crystal display device having the same according to the present invention, the first rigid reinforcing structure having both side ends bent on the lower cover and the second rigid reinforcing structure having the straight shape are integrally protruded, It is possible to prevent side effects such as ripple and white spots by improving the rigidity of the base plate.

1 is a schematic cross-sectional view of a liquid crystal display device having a backlight unit according to the related art.
2 is a plan view showing an outer bottom surface of a lower cover in a liquid crystal display device having a backlight unit according to the related art.
3 is a cross-sectional view of a lower cover in a liquid crystal display device having a backlight unit according to the related art.
4 is a cross-sectional view schematically showing a bent state of a lower cover in a liquid crystal display device having a backlight unit according to the related art.
FIG. 5 is a cross-sectional view schematically showing a twisted state of a lower cover in a liquid crystal display device having a backlight unit according to the related art.
6 is a schematic exploded perspective view of a liquid crystal display device having a backlight unit according to the present invention.
7 is a schematic cross-sectional view of a liquid crystal display device having a backlight unit according to the present invention.
8 is a plan view of a lower cover in a liquid crystal display device provided with a backlight unit according to the present invention.
FIG. 9 is a cross-sectional view taken along line IX-IX of FIG. 8, and is a schematic cross-sectional view illustrating a rigid reinforcing structure formed on the outer surface of the lower cover of the backlight unit according to the present invention.
FIG. 10 is a plan view of a lower cover in a liquid crystal display device having a backlight unit according to the present invention, and is a plan view schematically showing a plurality of points of a lower cover to which a load is applied. FIG.
11 is simulation data showing the change in stiffness of the lower cover when the same force is applied to each point shown in Fig.
12 is simulation data showing the change in stiffness of the lower cover when different forces are applied to each point shown in Fig.

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

6 is a schematic exploded perspective view of a liquid crystal display device having a backlight unit according to the present invention.

7 is a schematic cross-sectional view of a liquid crystal display device having a backlight unit according to the present invention.

8 is a plan view of a lower cover in a liquid crystal display device provided with a backlight unit according to the present invention.

FIG. 9 is a cross-sectional view taken along line IX-IX of FIG. 8, and is a schematic cross-sectional view illustrating a rigid reinforcing structure formed on the outer surface of the lower cover of the backlight unit according to the present invention.

A liquid crystal display device having a backlight unit according to the present invention, as shown in Figs. 6 and 7, includes a liquid crystal panel 106 for implementing an image; A guide panel 124 on which an edge of the liquid crystal panel 106 is seated and supported, a light source 120 provided on a lower portion of the liquid crystal panel 106, A light guide plate 116 for guiding the light incident from the light source unit 120 toward the liquid crystal panel 106, a reflection sheet 118 disposed on the back surface of the light guide plate 116, A light source housing 122 surrounding the light source unit 120 and a lower cover 126 accommodating the light source unit 120, the reflective sheet 118, the light guide plate 116, and the optical sheet 114, And a backlight unit (not shown).

Here, the guide panel 124 is a mold, and a locking portion (not shown) is formed on an inner upper edge of the guide panel 124 so that the edge portion of the liquid crystal panel 106 is seated and supported.

The light source 120 of the guide panel 124 and the light source housing 122 surrounding the light source 120 are disposed and the light guide plate 116 is disposed adjacent to the light source 120.

The light source unit 120 includes an LED element 120a and a substrate 120b on which the LED element 120a is mounted.

In addition, the light guide plate 116 serves to advance the light incident from the light source unit 120 toward the liquid crystal panel 106. In particular, the light guide plate 116 provides a light path so that light generated from the light source unit 120 spreads over the entire lower surface of the liquid crystal panel 106. The light guide plate 116 is mainly made of poly methyl methacrylate (PMMA).

The light source unit 120 and the light source housing 122 are disposed on one side of the light guide plate 116, that is, on the light entrance surface, and are used as a light source of the liquid crystal panel 106.

The light generated by the light source unit 120 is incident on the light guide plate 116 through the light incident surface formed on the side surface of the light guide plate 116.

The light source housing 122 is formed to surround the light source 120 and reflects the light generated from the light source 120 toward the light incident surface formed on the side surface of the light guide plate 116.

The liquid crystal panel 106 includes an upper substrate 103 and a lower substrate 105. The liquid crystal is injected between the upper substrate 103 and the lower substrate 105 of the liquid crystal panel 106, And a spacer (not shown) for maintaining a constant distance between the upper substrate 103 and the lower substrate 105.

Although not shown in the drawing, a color filter, a common electrode, a black matrix, and the like are formed on the upper substrate 103 of the liquid crystal panel 106. Although not shown in the figure, signal wirings such as data wirings and gate wirings are formed on the lower substrate 105 of the liquid crystal panel 106, and thin film transistors (TFTs) are formed on the intersections of the data wirings and the gate wirings. : TFT) is formed.

At this time, the thin film transistor switches a data signal to be transmitted from the data line to the liquid crystal cell in response to a scan signal (or gate pulse) input from the gate line.

A pixel electrode is formed in a pixel region between the data line and the gate line.

A signal line pad region (not shown) is formed on one side of the liquid crystal panel 106 to connect the data lines and the gate lines. A driver driving integrated circuit 110 A tape carrier package 108 is mounted. The tape carrier package 108 supplies a data signal to the data lines from the driver driving integrated circuit 110 and supplies a scan signal to the gate lines.

An upper polarizing sheet 104a is attached to the upper substrate 103 of the liquid crystal panel 106 and a lower polarizing sheet 104b is attached to the lower surface of the lower substrate 105. [

The top case 102 is formed in the shape of a rectangular band having a flat portion and a side portion bent at right angles and is fastened to the edge portion of the liquid crystal panel 106 and the guide panel 124 to be wrapped.

The lower cover 126 houses the light source unit 120, the reflection sheet 118, the light guide plate 116 and the optical sheet 114. The FPCB substrate A printed circuit board (not shown) is attached, and a buyer system is fastened to the center of the outer surface.

As shown in FIGS. 8 and 9, at the lower surface of the lower cover 126, at least two side edges are bent in a region excluding the one side edge portion 127, for example, a " Two first stiffening structures 128a and a second stiffening structure 18b in a straight shape are formed so as to protrude integrally.

At this time, the two first stiffening structures 128a are correspondingly spaced apart from each other, and the second stiffening structure 128b is formed on the lower side between the two first stiffening structures 128a, (Not shown). The first rigid reinforcing structure 128a and the second rigid reinforcing structure 128b are integrally formed so as to protrude integrally with each other. However, the first rigid reinforcing structure 128a and the second rigid reinforcing structure 128b may be combined with each other if necessary by separate fastening means.

The two first stiffening structures 128a are rigidly reinforced against forces applied in the longitudinal direction and the second stiffening structures 128b are rigidly reinforced against forces applied in the transverse direction give.

In particular, the two first stiffening structures 128a and the second stiffening structures 128b are formed at the edges of at least three sides of the lower cover 126. [

In addition, the number of the first stiffening structures 128a is not limited to two, but may be increased as needed. Also, the second rigid reinforcing structure 128b may be formed in a bent shape or a curved shape instead of a straight shape.

The reflective sheet 118 reflects light incident through the back surface of the light guide plate 116 toward the light guide plate 116 to reduce light loss.
The optical sheet 114 improves the light efficiency by vertically changing the optical path of the light emitted from the light source unit 120.

For this, the optical sheet 114 includes a lower diffusion sheet 114a for diffusing the light emitted from the light guide plate 116 to the entire area, and a lower diffusion sheet 114b for diffusing the progress angle of the light diffused by the lower diffusion sheet 114a into the liquid crystal panel Two prism sheets 114b and 114c vertically aligned with the prism sheets 106 and 106 and an upper diffusion sheet 114d for diffusing light transmitted through the two prism sheets 114b and 114c.

Accordingly, the light emitted from the light guide plate 116 is incident on the liquid crystal panel 106 via the plurality of optical sheets 114a, 114b, 114c, and 114d.

FIG. 10 is a plan view of a lower cover in a liquid crystal display device having a backlight unit according to the present invention, and is a plan view schematically showing a plurality of points of a lower cover to which a load is applied. FIG.

11 is simulation data showing the change in stiffness of the lower cover when the same force is applied to each point shown in Fig.

12 is a simulation data showing a change in stiffness of the lower cover when different forces are applied to each point shown in Fig.

10 is a graph showing a change in the force applied to the lower cover 126 when two first rigid reinforcing structures 128a and a second rigid reinforcing structure 128b are formed on the lower cover 126 To measure each point.

11, when the same force is applied in the vertical direction to each of the points A, B, C, D, E, F, G, H and I shown in Fig. 10, There is something to be improved. Particularly, in the case of the center point E of the lower cover 126 where deformation, i.e., warping or twisting, may be large, in the case of the present invention, the deformation of the lower cover is about 3.58, Is about 5.33.

Accordingly, as shown in FIG. 11, in the present invention, the rigidity of the lower cover 126 is improved by about 32.92% as compared with the prior art, so that it is understood that the deformation decreases as compared with the prior art.

12, when different forces are applied in the vertical direction to the respective points A, B, C, D, E, F, G, H and I shown in FIG. 10, Is improved. Particularly, in the case of the center point E of the lower cover 126 where deformation, i.e., warping or twisting, may be large, it is 1.39 in the case of the present invention, but it is about 1.92 in the case of the prior art.

Accordingly, in the case of the present invention, the stiffness is improved by about 27.65% as compared with the prior art, so that it is understood that the deformation decreases as compared with the conventional technique.

As described above, according to the backlight unit and the liquid crystal display device having the same according to the present invention, the first rigid reinforcing structure in which both side ends are bent on the lower cover and the second rigid reinforcing structure in a straight shape are integrally formed Thereby increasing the repulsive force against the force generated in the vertical direction, thereby minimizing the deformation amount deformed by the force, thereby preventing the interference.

In addition, according to the backlight unit and the liquid crystal display device having the same according to the present invention, the first rigid reinforcing structure in which both side ends are bent on the lower cover and the second rigid reinforcing structure in the shape of a rectangle are integrally formed so as to protrude, It is possible to prevent a side effect such as a ripple and a white spot by improving the rigidity of the metal plate.

102: Top case 104: Polarizing sheet
106: liquid crystal panel 114: optical sheet
116: light guide plate 118: reflective sheet
120: light source part 120a: LED element
120b: substrate 124: guide panel
126: Lower cover 128a: First stiffening structure
128b: second stiffening structure

Claims (10)

A light source unit for providing light;
A light guide plate arranged to be spaced apart from the light source unit and to transmit light emitted from the light source unit in the upward direction;
A plurality of optical sheets arranged on the light guide plate;
A guide panel disposed above the light source unit and supporting the liquid crystal panel; And
Wherein the light source unit and the light guide plate are housed in a first region where an outer surface is attached to a flexible printed circuit board (FPCB) and a second region adjacent to the first region, A lower cover having a rigid reinforcing structure and a second rigid reinforcing structure,
Wherein the first rigid reinforcing structure is arranged in a "C" shape in which both side ends are bent, and the second rigid reinforcing structure is arranged in a straight line shape. delete The backlight unit according to claim 1, wherein the second rigid reinforcing structure is disposed along the longitudinal direction of the lower cover. delete The backlight unit according to claim 1, wherein the rigid reinforcing structure is formed integrally with the lower cover. A liquid crystal panel in which a screen is implemented;
A light source unit disposed below the liquid crystal panel and providing light to the liquid crystal panel;
A light guide plate arranged to be spaced apart from the light source unit and to transmit light emitted from the light source unit in the upward direction;
A plurality of optical sheets arranged on the light guide plate;
A guide panel disposed above the light source unit and supporting the liquid crystal panel; And
Wherein the light guide plate and the light guide plate are accommodated in a first region in which an outer surface is attached to a flexible printed circuit board (FPCB) and a second region adjacent to the first region, Wherein the first rigid reinforcing structure is arranged in a "C" shape in which both side ends are bent and the second rigid reinforcing structure is arranged in a straight line, . delete The liquid crystal display of claim 6, wherein the second rigid reinforcing structure comprises a backlight unit disposed along a longitudinal direction of the lower cover. delete The liquid crystal display of claim 6, wherein the rigid reinforcing structure comprises a backlight unit formed to protrude integrally with the lower cover.

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