KR20060063415A - Back light assembly and liquid crystal display apparatus having the same - Google Patents

Abstract

A backlight assembly capable of improving luminance uniformity and a liquid crystal display device having the same are disclosed. The backlight assembly includes a flat fluorescent lamp that is divided into a plurality of discharge spaces to generate light, and a bottom chassis that includes a bottom portion and a side to accommodate the flat fluorescent lamp. At least one first hole is formed in the side portion of the bottom chassis that is parallel to the longitudinal direction of the discharge space. A second hole is formed in the bottom of the bottom chassis corresponding to the electrode of the flat fluorescent lamp. The backlight assembly further includes a buffer member disposed between the flat fluorescent lamp and the bottom chassis to support the flat fluorescent lamp. Therefore, it is possible to reduce the leakage current in the discharge space adjacent to the outside to improve the luminance uniformity of the light emitted from the flat fluorescent lamp.

Description

BACK LIGHT ASSEMBLY AND LIQUID CRYSTAL DISPLAY APPARATUS HAVING THE SAME}

1 is an exploded perspective view showing a backlight assembly according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view illustrating a combined cross section of the backlight assembly illustrated in FIG. 1.

3 is a plan view illustrating a side of the bottom chassis illustrated in FIG. 1.

4 is a plan view illustrating another embodiment of the first holes illustrated in FIG. 3.

FIG. 5 is a plan view illustrating still another embodiment of the first holes illustrated in FIG. 3.

6 is a perspective view illustrating another embodiment of the bottom chassis shown in FIG. 1.

FIG. 7 is a cross-sectional view of the flat fluorescent lamp shown in FIG. 1.

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

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

100: backlight assembly 200: flat fluorescent lamp

210: lamp body 220: electrode

300: bottom chassis 310: bottom portion                 

320: side 322: first hole

400: buffer member 510: second hole

610: inverter 620: diffuser plate

630: optical sheet 700: display unit

710: liquid crystal display panel 720: driving circuit unit

The present invention relates to a backlight assembly and a liquid crystal display device having the same, and more particularly, to a backlight assembly and a liquid crystal display device having the same that can improve the luminance uniformity of light generated.

In general, a liquid crystal display (Liquid Crystal Display) is a flat panel display device that displays an image by using a liquid crystal (Liquid Crystal), thinner and lighter than other display devices, has the advantage of low driving voltage and low power consumption This has been widely used throughout the industry.

Since the liquid crystal display device is a non-light emitting device which does not emit light by itself, the liquid crystal display panel for displaying an image requires a separate backlight assembly for supplying light to the liquid crystal display panel.

Conventional backlight assembly mainly uses a cold, long cylindrical cold cathode fluorescent lamp (CCFL) as a light source. However, as the size of liquid crystal displays increases, the number of cold cathode fluorescent lamps required increases, resulting in increased manufacturing costs and inferior optical characteristics such as luminance uniformity.

In order to solve this problem, the development of a flat fluorescent lamp that emits light directly in the form of a plane has recently been in progress. The flat fluorescent lamp includes a lamp body having an internal space divided into a plurality of discharge spaces and an electrode for applying a discharge voltage to the lamp body. Such flat fluorescent lamps generate plasma discharges in respective discharge spaces by discharge voltages applied from the inverter to the electrodes. At this time, the fluorescent film formed inside the lamp body is excited by the ultraviolet rays generated by the plasma discharge to generate visible light.

However, when driving the flat fluorescent lamp, there is a problem that the luminance of the discharge spaces located at the top and bottom of the discharge spaces closest to the outer side is lower than that of the other discharge spaces. Such a decrease in luminance is caused by a leakage current generated between the flat fluorescent lamp and the bottom chassis of the metal material, which causes a problem of deterioration in luminance uniformity and appearance quality of the liquid crystal display.

Accordingly, the present invention has been made in view of such a problem, and an object of the present invention is to provide a backlight assembly capable of improving appearance quality by improving luminance uniformity of light emitted from a flat fluorescent lamp.

Another object of the present invention is to provide a liquid crystal display device having the backlight assembly as described above.

The backlight assembly for achieving the above object of the present invention includes a flat fluorescent lamp and a bottom chassis. The backlight assembly is divided into a plurality of discharge spaces to generate light. The bottom chassis includes a bottom portion and a side portion to receive the flat fluorescent lamp, and at least one first hole is formed at a side portion parallel to a length direction of the discharge space.

The first hole is formed along a length direction of the discharge space.

A second hole is formed in the bottom of the bottom chassis to correspond to the electrodes of the flat fluorescent lamp.

A liquid crystal display device for achieving another object of the present invention includes a backlight assembly and a liquid crystal display panel. The backlight assembly may include a flat panel fluorescent lamp divided into a plurality of discharge spaces to generate light, and a bottom portion and a side portion to accommodate the flat fluorescent lamp, and at least one first side of the backlight assembly may be parallel to a length direction of the discharge space. And a bottom chassis with holes formed therein. The liquid crystal display panel displays an image using light supplied from the backlight assembly.

According to the backlight assembly and the liquid crystal display having the same, the luminance uniformity of the light emitted from the flat panel fluorescent lamp can be improved by reducing the leakage current of the discharge space adjacent to the outside.

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

1 is an exploded perspective view showing a backlight assembly according to an embodiment of the present invention, Figure 2 is a cross-sectional view showing a combined cross-section of the backlight assembly shown in FIG.

1 and 2, the backlight assembly 100 according to an embodiment of the present invention includes a flat fluorescent lamp 200 and a bottom chassis 300.

The flat fluorescent lamp 200 includes a lamp body 210 for generating light and electrodes 220 formed at both ends of the lamp body 210. The lamp body 210 is formed so that the plane viewed from above has a quadrangular shape in order to emit light in a plane form. The flat panel fluorescent lamp 200 generates a plasma discharge in an internal space by a discharge voltage applied from an external inverter, and converts ultraviolet rays generated by the plasma discharge into visible light and emits it to the outside. Since the flat fluorescent lamp 200 has a large light emitting area, the internal space is divided into a plurality of discharge spaces 250 in order to improve the light emitting efficiency. The electrodes 220 extend in a direction perpendicular to the longitudinal direction of the discharge spaces 250 to cross all the discharge spaces 250.

The bottom chassis 300 includes a bottom portion 310 and a side portion 320 extending from an edge of the bottom portion 310 to form an accommodation space for accommodating the flat fluorescent lamp 200. Side 320 is, for example, has a shape bent in a U-shape to provide a bonding area with other components and to improve mechanical strength. The bottom chassis 300 is made of a metal having high strength and low deformation.                     

The bottom chassis 300 has a first hole 322 formed to reduce electrical interference with the received flat fluorescent lamp 200. At least one first hole 322 is formed in the side portion 320 parallel to the longitudinal direction of the discharge space 250. The first hole 322 is formed to have a predetermined length along the length direction of the discharge space 250, that is, the length direction of the side part 320. A leakage current due to parasitic capacitance is generated between the flat fluorescent lamp 200 and the bottom chassis 300. The first hole 322 reduces parasitic capacitance between the planar fluorescent lamp 200 and the bottom chassis 300, thereby reducing leakage current leaking from the discharge space 250 positioned at the outermost portion of the planar fluorescent lamp 200. Let's do it.

The backlight assembly 100 further includes a buffer member 400 disposed between the flat fluorescent lamp 200 and the bottom chassis 300 to support the flat fluorescent lamp 200. The buffer member 400 is disposed to correspond to the edge of the flat fluorescent lamp 200, and the flat fluorescent lamp 200 is spaced apart from the bottom chassis 300 by a predetermined distance to the flat fluorescent lamp 200 and the bottom chassis 300. Shut off electrical contact between the liver. The buffer member 400 is made of an insulating material. In addition, the buffer member 400 is preferably made of a material having a certain degree of elasticity to absorb the impact applied from the outside. For example, the buffer member 400 is made of silicon (Silicin) material. On the other hand, the buffer member 400 may cover the first hole 322 formed in the side portion 320 of the storage container 300, it is possible to prevent the foreign material from flowing through the first hole (322).

In this embodiment, the buffer member 400 is composed of two pieces having a "c" shape. On the other hand, the buffer member 400 is composed of four pieces corresponding to each side of the flat fluorescent lamp 200, or four pieces of "A" shape corresponding to the four corners of the flat fluorescent lamp 200 It may be made or formed integrally in the shape of a frame.

3 is a plan view illustrating a side of the bottom chassis illustrated in FIG. 1.

Referring to FIG. 3, first holes 322 are formed in the side portion 320 of the bottom chassis 300 to reduce electrical interference with the planar fluorescent lamp 200. The number and shape of the first holes 322 are determined in consideration of the leakage current of the plate fluorescent lamp 200 and the mechanical strength of the bottom chassis 300. In this embodiment, the first holes 322 are made up of two. Each first hole 322 has a rectangular shape extending along the longitudinal direction of the side portion 320. In addition, the first holes 322 are formed to be spaced apart by a predetermined distance in consideration of the mechanical strength of the bottom chassis 300.

4 is a plan view illustrating another embodiment of the first holes illustrated in FIG. 3.

Referring to FIG. 4, first holes 324 are formed in the side portion 320 of the bottom chassis 300 to reduce electrical interference with the planar fluorescent lamp 200. The first holes 324 are composed of four. Each first hole 324 has a rectangular shape extending along the longitudinal direction of the side portion 320. In addition, the first holes 324 have a structure spaced apart at regular intervals in consideration of the mechanical strength of the bottom chassis 300.

FIG. 5 is a plan view illustrating still another embodiment of the first holes illustrated in FIG. 3.

Referring to FIG. 5, first holes 326 are formed in the side portion 320 of the bottom chassis 300 to reduce electrical interference with the planar fluorescent lamp 200. Each first hole 326 has an elliptical shape having a long axis in the longitudinal direction of the side portion 320. The first holes 326 are composed of two. The first holes 322 are formed to be spaced apart by a predetermined distance in consideration of the mechanical strength of the bottom chassis 300.

The shape and number of the first holes may be variously modified in consideration of leakage current of the flat fluorescent lamp and mechanical strength of the bottom chassis.

6 is a perspective view illustrating another embodiment of the bottom chassis shown in FIG. 1.

1 and 6, the bottom chassis 500 according to another embodiment of the present invention is

The bottom chassis 500 includes a bottom portion 510 and a side portion 520 extending from an edge of the bottom portion 510 to form an accommodation space for accommodating the flat fluorescent lamp 200. The side portion 520 is, for example, shaped to be bent in a U shape to provide a bonding area with other components and to improve mechanical strength. The bottom chassis 500 is made of a metal having high strength and low deformation.

The bottom chassis 500 is provided with a first hole 522 and a second hole 512 in order to reduce leakage current of the received flat fluorescent lamp 200.

At least one first hole 522 is formed in the side portion 520 parallel to the longitudinal direction of the discharge space 250. The first hole 522 is formed to have a predetermined length along the length direction of the discharge space 250, that is, the length direction of the side portion 520. The first hole 522 reduces the parasitic capacitance between the planar fluorescent lamp 200 and the bottom chassis 500, thereby reducing the leakage current leaking from the discharge space 250 positioned at the outermost portion of the planar fluorescent lamp 200. Let's do it.

The second hole 512 is formed in the bottom 510 of the bottom chassis 500 corresponding to the position of the electrode 220 of the flat fluorescent lamp 200. The second hole 512 reduces the leakage current generated by the electrical interference between the electrode 220 and the bottom chassis 500 to which a high voltage is applied, thereby improving the discharge efficiency of the flat fluorescent lamp 200. The second hole 512 may have a structure divided into a plurality of holes in consideration of the mechanical strength of the bottom chassis 500.

FIG. 7 is a cross-sectional view of the flat fluorescent lamp shown in FIG. 1.

1 and 7, a flat fluorescent lamp (FFL) 200 includes a lamp body 210 for generating light and electrodes 220 formed at both ends of the lamp body 210, respectively. do.

The lamp body 210 includes a first substrate 230 and a second substrate 240 coupled to the first substrate 240 to form a plurality of discharge spaces 250.

The first substrate 230 has a rectangular plate shape. For example, the first substrate 230 is made of glass. The first substrate 230 may include a material that blocks ultraviolet rays so that ultraviolet rays generated in the discharge spaces 250 do not leak.

The second substrate 240 is formed between the discharge space portions 242 spaced apart from the first substrate 230 to form the discharge spaces 250 and the discharge space portions 242 adjacent to each other. And a sealing part 246 formed at edges of the space dividing parts 244 and the discharge space parts 242 and the space dividing parts 244 in contact with the first substrate 230. The second substrate 240 is made of a transparent material through which visible light generated in the discharge spaces 250 can pass. For example, the second substrate 240 is made of glass. The second substrate 240 may include a material that blocks ultraviolet rays so that ultraviolet rays generated in the discharge spaces 250 do not leak.                     

Connection passages 270 are formed in the second substrate 240 to connect the discharge spaces 250 adjacent to each other. At least one connection passage 270 is formed in each space division part 244. The connection passage 270 may provide a passage through which air or discharge gas may move when exhausting air existing in the discharge spaces 250 or injecting discharge gas into the discharge spaces 250. The connection passage 270 may have various shapes as long as it can connect the adjacent discharge spaces 250 with each other. For example, the connection passage 270 has a structure bent in an S shape.

The second substrate 240 is coupled to the first substrate 230 through the adhesive member 260. For example, the adhesive member 260 is formed of a frit that is a mixture of glass and metal having a lower melting point than glass. The first substrate 230 and the second substrate 240 may be fired by interposing the adhesive member 260 between the first substrate 230 and the second substrate 240 through the adhesive member 260. Combined with each other.

The lamp body 210 includes a reflective film 280 formed on an inner surface of the first substrate 230, that is, a surface facing the second substrate 240, a first fluorescent film 292 and an upper portion of the reflective film 280. A second fluorescent film 294 is further formed on an inner surface of the second substrate 292, that is, a surface facing the first substrate 230. The reflective film 280 reflects visible light generated by the first fluorescent film 292 and the second fluorescent film 294 to prevent leakage of visible light through the first substrate 230. The first fluorescent film 292 and the second fluorescent film 294 are excited by ultraviolet rays generated through plasma discharge in the discharge spaces 250 to emit visible light.

The electrodes 220 are formed to intersect all the discharge spaces 250 on the outer surface of the second substrate 240. The electrodes 220 are formed to correspond to both ends of the discharge space portions 242 in the longitudinal direction. The electrodes 220 extend in a direction perpendicular to the length direction of the discharge space portions 242 and overlap with all the discharge spaces 250. The electrodes 220 are made of a conductive material to transfer a discharge voltage applied from an external inverter to the lamp body 210. Meanwhile, the electrodes 220 may also be formed on the outer surface of the first substrate 230. When the electrodes 220 are formed on the first substrate 230 and the second substrate 240, respectively, the electrodes 230 formed on the first substrate 230 and the electrodes 230 formed on the second substrate 240 may be formed. They are connected to each other by conductive clips. In addition, the electrodes 220 may be formed inside the lamp body 210.

In the present embodiment, the lamp body has a shape in which the second substrate is molded to form a plurality of discharge spaces, but on the contrary, the second substrate has the same plate shape as the first substrate, and the first substrate and the second substrate. The lamp body may have a structure in which barrier ribs for dividing the discharge space are formed between the substrates.

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

Referring to FIG. 8, the liquid crystal display 800 according to the exemplary embodiment of the present invention includes a backlight assembly 600 and a display unit 700.

The backlight assembly 600 includes a flat fluorescent lamp 200, a bottom chassis 300, and a buffer member 400. In the present embodiment, since the plate fluorescent lamp 200, the bottom chassis 300 and the buffer member 400 has the same structure as shown in Fig. 1, the same reference numerals are used, and detailed description thereof will be omitted. Let's do it.                     

The backlight assembly 600 is disposed above the inverter 610 and the planar fluorescent lamp 200 generating a discharge voltage for driving the planar fluorescent lamp 200 to diffuse the light emitted from the planar fluorescent lamp 200. To further include the diffusion plate 620 and the optical sheet 630 disposed on the diffusion plate 620.

The inverter 610 boosts the low-voltage alternating voltage applied from the outside to a high-voltage alternating voltage suitable for driving the flat fluorescent lamp 200 and outputs a discharge voltage. The inverter 610 is disposed on the rear surface of the bottom chassis 300. The discharge voltage generated from the inverter 610 is applied to the electrodes 220 of the flat panel fluorescent lamp 200 through the first power line 612 and the second power line 614.

The diffusion plate 620 diffuses the light emitted from the flat plate fluorescent lamp 200 to improve the brightness uniformity of the light. The diffusion plate 620 is formed in a plate shape having a predetermined thickness and is spaced apart from the flat plate fluorescent lamp 200 at a predetermined interval. The diffusion plate 620 is made of, for example, polymethyl methacrylate (PMMA), and contains a diffusion agent for diffusing light therein.

The optical sheet 630 changes the path of the light diffused through the diffusion plate 620 to improve the luminance characteristic. The optical sheet 630 may include a light collecting sheet for condensing the light diffused through the diffusion plate 620 in the front direction to improve the front brightness of the light. In addition, the optical sheet 630 may include a diffusion sheet for improving the luminance uniformity by diffusing the light diffused through the diffusion plate 620 once again. Meanwhile, the backlight assembly 600 may add or remove optical sheets having various functions according to required brightness characteristics.

The display unit 700 includes a liquid crystal display panel 710 for displaying an image using light supplied from the backlight assembly 600, and a driving circuit unit 720 for driving the liquid crystal display panel 710.

The liquid crystal display panel 710 includes a thin film transistor (hereinafter, referred to as TFT) substrate 712, a color filter substrate 714 coupled to the TFT substrate 712, and the two substrates 712 and 714. And a liquid crystal 716 interposed therebetween.

The TFT substrate 712 is a transparent glass substrate on which a switching element TFT (not shown) is formed in a matrix form. Data and gate lines are respectively connected to the source and gate terminals of the TFTs, and a pixel electrode (not shown) made of a transparent conductive material is connected to the drain terminal.

The color filter substrate 714 is a substrate in which RGB pixels (not shown) which are color pixels are formed by a thin film process. A common electrode (not shown) made of a transparent conductive material is formed on the color filter substrate 714.

In the liquid crystal display panel 710 having such a configuration, when power is applied to the gate terminal of the TFT and the TFT is turned on, an electric field is formed between the pixel electrode and the common electrode. Due to this electric field, the arrangement of the liquid crystal 716 interposed between the TFT substrate 712 and the color filter substrate 714 is changed, and is supplied from the flat fluorescent lamp 510 according to the arrangement change of the liquid crystal 716. The transmittance of light is changed to obtain an image of a desired gray scale.

The driving circuit 720 includes a data printed circuit board 722 for supplying a data driving signal to the liquid crystal display panel 710, a gate printed circuit board 724 for supplying a gate driving signal to the liquid crystal display panel 710, and data printing. The data flexible circuit film 726 connects the circuit board 722 to the liquid crystal display panel 710 and the gate flexible circuit film 728 connects the gate printed circuit board 724 to the liquid crystal display panel 710. . The data flexible circuit film 726 and the gate flexible circuit film 728 are made of, for example, a tape carrier package (TCP) or a chip on film (COF). Meanwhile, the gate printed circuit board 724 may be removed by forming separate signal wires (not shown) on the liquid crystal display panel 710 and the gate flexible circuit film 728.

According to the backlight assembly and the liquid crystal display having the same, the first hole is formed on the side of the bottom chassis corresponding to the discharge space adjacent to the outside to reduce the leakage current of the flat fluorescent lamp and to uniform the luminance of the light emitted from the flat fluorescent lamp. Can improve the sex.

In addition, the second hole may be formed in the bottom of the bottom chassis corresponding to the electrode of the flat fluorescent lamp to improve the discharge efficiency of the flat fluorescent lamp.

In the detailed description of the present invention described above with reference to the preferred embodiments of the present invention, those skilled in the art or those skilled in the art having ordinary skill in the art will be described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

Claims (11)

A flat fluorescent lamp divided into a plurality of discharge spaces to generate light; And The backlight assembly includes a bottom chassis having a bottom portion and a side portion to receive the flat fluorescent lamp, and a bottom chassis having at least one first hole formed at a side portion parallel to a length direction of the discharge space. The backlight assembly of claim 1, wherein the first hole is formed along a length direction of the discharge space. The method of claim 1, wherein the flat fluorescent lamp Lamp body; And And electrodes formed at both ends of the lamp body and extending in a direction perpendicular to the length direction of the discharge space to intersect all the discharge spaces. The backlight assembly of claim 3, wherein a second hole is formed at a bottom of the bottom chassis to correspond to the electrodes. The method of claim 3, wherein the lamp body is A first substrate; And Space dividers spaced apart from the first substrate to form the discharge spaces, space dividers formed between the space dividers and contacting the first substrate, and formed at edges of the discharge spaces and the space dividers, And a second substrate having a sealing portion coupled with the first substrate. The method of claim 1, And a buffer member disposed between the plate fluorescent lamp and the bottom chassis to support the plate fluorescent lamp. A flat plate fluorescent lamp divided into a plurality of discharge spaces to generate light, and a bottom portion and a side portion to accommodate the flat plate fluorescent lamp, and at least one first hole is formed at a side portion parallel to the longitudinal direction of the discharge space. A backlight assembly comprising a chassis; And And a liquid crystal display panel for displaying an image using light supplied from the backlight assembly. The liquid crystal display of claim 7, wherein the first hole is formed along a length direction of the discharge space. The liquid crystal display of claim 7, wherein a second hole is formed in a bottom portion of the bottom chassis in a direction perpendicular to a length direction of the first hole. 10. The liquid crystal display device according to claim 9, wherein the second hole corresponds to an electrode position of the flat fluorescent lamp. The method of claim 7, wherein the backlight assembly A buffer member disposed between the plate fluorescent lamp and the bottom chassis to support the plate fluorescent lamp; A diffusion plate disposed on the flat fluorescent lamp and diffusing the light emitted from the flat fluorescent lamp; An optical sheet disposed on the diffusion plate; And And an inverter for generating a discharge voltage for driving the flat fluorescent lamp.

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