KR20050098355A - Surface light source device and liquid crystal display device having the same - Google Patents

Abstract

Disclosed are a surface light source device capable of improving luminance uniformity and a liquid crystal display device having the same. The surface light source device is formed on a light source body having an inner space divided into a plurality of discharge spaces, an outer surface of the light source body, and is formed at both ends in the longitudinal direction of the discharge space so as to intersect the plurality of discharge spaces, and the length of the discharge space. The electrode width extending in parallel to the direction includes first and second electrodes formed differently according to the overlapping discharge space. At this time, the electrode width of each of the first and second electrodes increases as the distance from the center to the direction perpendicular to the longitudinal direction of the discharge space. Accordingly, the luminance uniformity and the display quality of the emitted light can be improved by preventing the lowering of the luminance generated at the upper end and the lower end of the light source body.

Description

Surface light source device and liquid crystal display device having the same {SURFACE LIGHT SOURCE DEVICE AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THE SAME}

The present invention relates to a surface light source device and a liquid crystal display device having the same, and more particularly, to a surface light source device having a light source body emitting light in a plane form and an external electrode for applying a discharge voltage to the light source body. It relates to a liquid crystal display device to be used.

In general, a liquid crystal display is a flat panel display that displays an image using liquid crystal, and is thinner and lighter than other display devices, and has a low power consumption and a low driving voltage. This has been widely used throughout the industry.

Such a liquid crystal display device requires a backlight assembly that provides a separate light source because the liquid crystal display panel for displaying an image is a non-light emitting device that does not emit light by itself.

In the conventional backlight assembly, a cold cathode fluorescent lamp (CCFL) having a tubular shape is mainly used as a light source. Backlight assemblies using a cold cathode fluorescent lamp as a light source are classified into an edge type and a direct type according to the position of the light source. The edge type emits light to the liquid crystal display panel by placing light sources on the side of the transparent light guide plate and reflecting light using one side of the light guide plate. The direct type emits a plurality of light sources directly below the liquid crystal display panel. The light source is positioned in front of the light source, and a diffuser plate is disposed on the back of the light source, and a reflector is disposed on the back of the light source to reflect and diffuse light emitted from the light source.

Such a conventional backlight assembly has a problem in that light loss caused by an optical member such as a light guide plate or a diffusion plate is low, and thus the light utilization efficiency is low, and the overall structure is complicated, resulting in high production cost and inferior uniformity of luminance.

In order to solve such a problem, the development of the surface light source device which directly emits light in the form of a plane is in progress in recent years. The surface light source device includes a light source body having an internal space divided into a plurality of discharge spaces, and electrodes formed at both ends of the light source body to apply a discharge voltage to the light source body. At this time, each discharge space is formed so that a portion of the discharge space is in communication with the adjacent discharge space for uniform distribution of the discharge gas. Such a surface light source causes plasma discharge in each discharge space by a discharge voltage applied to an electrode from the outside, and emits light using the surface light source.

However, when driving such a surface light source device, there is a problem that the luminance of the discharge spaces located at the top and the bottom of the discharge spaces, that is, the discharge spaces closest to the outside of the light source body is lower than that of the other discharge spaces. . In particular, when the surface light source device is combined with a storage container and other components to produce a backlight assembly, the luminance deterioration problem is more prominent, which causes a problem of lowering luminance uniformity and display quality.

Accordingly, the present invention has been made in view of such a problem, and an object of the present invention is to provide a surface light source device which can improve luminance uniformity and display quality of emitted light by preventing the luminance of discharge spaces located at the top and bottom thereof from being lowered. It is.

Another object of the present invention is to provide a liquid crystal display device having the surface light source device as a light source.

The surface light source device for achieving the above object of the present invention includes a light source body, first and second electrodes.

The light source body has an internal space divided into a plurality of discharge spaces for generating light.

The first and second electrodes are formed on the outer surface of the light source body, and are formed at both ends in the longitudinal direction of the discharge space so as to intersect the plurality of discharge spaces, and extend in parallel with the longitudinal direction between the discharge lights. The electrode width is formed differently according to the discharge spaces overlapping each other. For example, the electrode width of each of the first and second electrodes is formed to increase as the distance from the center to the direction perpendicular to the longitudinal direction of the discharge space.

A liquid crystal display device for achieving another object of the present invention includes a surface light source device, a storage container, a liquid crystal display device and an inverter.

The surface light source device is a light source body having an internal space divided into a plurality of discharge spaces for the generation of light, respectively formed at both ends of the light source body to intersect the plurality of discharge spaces and in parallel with the longitudinal direction of the discharge space The extending electrode width includes first and second electrodes formed differently according to the discharge spaces overlapping each other.

The storage container houses the surface light source device.

The liquid crystal display panel displays an image by using light emitted from the surface light source device.

The inverter is disposed on the rear surface of the storage container, and applies a discharge voltage for driving the surface light source device to the first and second electrodes.

The liquid crystal display further includes a light diffusing member disposed between the surface light source device and the liquid crystal display panel and a fixing member for fixing the liquid crystal display panel to the storage container.

According to such a surface light source device and a liquid crystal display device having the same, the uniformity of luminance and display quality of the surface light source device can be improved by forming the electrode widths of the first and second electrodes differently according to overlapping discharge spaces.

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 surface light source device according to an embodiment of the present invention, Figure 2 is a cross-sectional view of the surface light source device shown in FIG.

1 and 2, the surface light source device 1000 according to an exemplary embodiment of the present invention may include a light source body 100 generating light and first and second portions formed at both ends of an outer surface of the light source body, respectively. Electrodes 210 and 220.

The light source body 100 combines the first substrate 110, the second substrate 120 disposed to face the first substrate 110 at a predetermined interval, and the first substrate 110 and the second substrate 120. To form an inner space.

The first and second substrates 110 and 120 have a flat plate shape. For example, the first and second substrates 110 and 120 may be transparent glass substrates that transmit visible light and block ultraviolet rays. The sealing member 130 is disposed between the first and second substrates 110 and 120, and seals an outer edge of the first and second substrates 110 and 120 to form an empty space therein.

The light source body 100 further includes a plurality of space dividing members 140 disposed in the inner space. The space dividing member 140 is disposed at equal intervals at least one or more parallel to each other in order to divide the internal space of the light source body 100 into a plurality of discharge space 150. Each of the space dividing members 140 has a rod shape extending in one direction, and the upper and lower parts of the space dividing member 140 are in close contact with the second substrate 120 and the first substrate 110. In addition, each of the space dividing members 140 is formed such that at least one end of both ends in the longitudinal direction is spaced apart from the inner surface of the sealing member 130 by a predetermined distance. This is to provide a connection path so that the discharge gas injected into the inner space of the light source body 100 can be uniformly distributed in the plurality of discharge spaces 150.

Meanwhile, the light source body 100 may include the first and second fluorescent layers 160 and 170 formed on opposite surfaces of the first and second substrates 110 and 120, respectively, and the first substrate 110. It further includes a reflective layer 180 formed between the first fluorescent layer 160. The first and second fluorescent layers 160 and 170 are formed in a thin film form on each of the opposing surfaces of the first and second substrates 110 and 120 except for a region in which the space dividing member 140 is disposed. At this time, although not shown, a fluorescent layer may be formed on the side of the space dividing member 140. The first and second fluorescent layers 160 and 170 are excited by ultraviolet rays generated through plasma discharge to emit visible light. The reflective layer 180 reflects the visible light generated by the first and second fluorescent layers 160 and 170 toward the second substrate 120 to prevent light from leaking to the first substrate 110.

In addition, the light source body 100 may include a protective layer (not shown) formed between the second substrate 120 and the second fluorescent layer 170 and / or between the first substrate 110 and the reflective layer 180. It may further include. The protective layer prevents chemical reaction between the second or first substrate 120 and 110 and mercury, which is a main component of the discharge gas, to prevent the loss of mercury.

The first and second electrodes 210 and 220 are formed on the outer surface of the light source body, and both ends in the longitudinal direction of the discharge space 150, that is, the space dividing member 140, intersect the plurality of discharge spaces 150. It is formed at both ends in the longitudinal direction, respectively. In this case, each of the first and second electrodes 210 and 220 is formed differently according to the discharge space in which the electrode width BW extending in parallel with the length direction of the discharge space 150 overlaps. For example, the electrode width BW of each of the first and second electrodes 210 and 220 is formed to increase in a direction perpendicular to the longitudinal direction of the discharge space 150 from the center. As such, the electrode widths BW of the first and second electrodes 210 and 220 overlapping with the discharge spaces positioned at the top and the bottom of the luminance, which are lower than those of the other regions, may be increased to prevent the luminance from being lowered and to improve the luminance uniformity. Can be.

In the present embodiment, the first and second electrodes 210 and 220 are materials having excellent conductivity, for example, copper (Cu), nickel (Ni), silver (Ag), gold (Au), and aluminum (Al). , Is formed by a method of spray coating a metal powder (Cr) made of chromium (Cr). That is, after the mask is disposed in an area of the outer surface of the light source body 100 except for the positions where the first and second electrodes 210 and 220 are formed, the mask is positioned at the positions where the first and second electrodes 210 and 220 are formed. The first and second electrodes 210 and 220 are formed by coating the metal powder with a spray method and then removing the mask. Alternatively, the first and second electrodes 210 and 220 may be formed by attaching aluminum tape or coating silver paste. In addition, the first and second electrodes 210 and 220 may be formed of a transparent conductive material, for example, indium tin oxide (ITO) or indium zinc oxide (IZO). As such, when the first and second electrodes 210 and 220 are made of a transparent material, even when the first and second electrodes 210 and 220 are actually formed inside the effective light emitting area that affects the display of the image, the dark portion may be caused. It is possible to prevent display defects such as these.

In the present embodiment, the first and second electrodes 210 and 220 are formed only on the outer surface of the first substrate 110 on which the reflective layer 180 is formed so as not to affect the light emitted from the light source body 100. desirable. However, the first and second electrodes 210 and 220 may be formed only on the outer surface of the second substrate 120 or may be formed on both the outer surfaces of the first and second substrates 110 and 120.

3 is a plan view illustrating the first and second electrodes illustrated in FIG. 1.

Referring to FIG. 3, the first and second electrodes 210 and 220 are symmetrically formed at both ends of the light source body 100. Each of the first and second electrodes 210 and 220 is formed such that the electrode width BW changes in the extending direction. Specifically, the electrode width BW of each of the first and second electrodes 210 and 220 increases so as to move away from the center CE to both ends, that is, in a direction perpendicular to the longitudinal direction of the discharge space. Is formed. In this embodiment, the electrode width BW increases linearly as it goes from the center CE to both ends.

In general, the luminance of the light emitted from the surface light source device 1000 is closely related to the amount of current formed in the discharge space 150, and the amount of internal current is determined by the change in the area of the first and second electrodes 210 and 220. Determined by the capacitance. That is, as the capacitance increases, the luminance increases in proportion to the capacitance at a level below the saturation current. Therefore, in order to increase the luminance in the discharge space 150 positioned at the upper end and the lower end having relatively low luminance, the first and second electrodes 210 and 220 overlapping the discharge space 150 positioned at the upper end and the lower end. By increasing the electrode width BW, the luminance can be improved at the same time as the capacitance is increased.

Meanwhile, the shapes of the first and second electrodes 210 and 220 may be modified into various geometric shapes according to luminance and luminance uniformity to be obtained.

4 is a plan view illustrating another example of the first and second electrodes illustrated in FIG. 3.

Referring to FIG. 4, the first and second electrodes 240 and 250 according to another embodiment may include both ends of the light source body 100, that is, the first and second electrodes 210 and 220 illustrated in FIG. 3. It is formed at the same position as the formation position. The first and second electrodes 240 and 250 are formed to have a constant electrode width BW in a region overlapping with the discharge space 150 of the center portion where the luminance is uniformly uniform among the plurality of discharge spaces 150. In the region overlapping with the discharge space 150 of the upper end portion and the lower end portion having low luminance, the electrode width BW is increased. Specifically, the electrode width BW of each of the first and second electrodes 240 and 250 is a constant electrode width from the center CE to the first point P1 in a direction perpendicular to the longitudinal direction of the discharge space 150. Although formed as BW, the electrode width BW gradually increases from the first point P1 to the end. Here, the electrode width BW may increase in a step shape or linearly toward the end from the first point P1. As such, by increasing the areas of the first and second electrodes 240 and 250 overlapping with the discharge spaces 150 of the upper and lower ends where the luminance is relatively low, the overall luminance uniformity may be improved.

5 is a perspective view showing another embodiment of the light source body shown in FIG. 1, and FIG. 6 is a cross-sectional view of the light source body shown in FIG. 5. In the present embodiment, since the first and second electrodes are the same as those shown in FIGS. 1 to 4, duplicate description thereof will be omitted.

5 and 6, the light source body 300 according to another embodiment may be coupled to the first substrate 310 and the first substrate 310 to form a second substrate (ie, a plurality of discharge spaces 370). 320).

The first substrate 310 has a rectangular flat plate shape. For example, the first substrate 310 is a transparent glass substrate that transmits visible light and blocks ultraviolet rays.

The second substrate 320 is combined with the first substrate 310 to form an internal space. For example, the second substrate 320 is made of the same transparent glass substrate as the first substrate 310. The second substrate 320 may include a light emitter 322 spaced apart from the first substrate 310 to form an internal space, and a first substrate 310 to divide the internal space into a plurality of discharge spaces 370. It consists of a space dividing unit 324 in contact with. The space dividing unit 324 is formed to be parallel to each other at regular intervals. The second substrate 320 having such a shape is formed by, for example, forming. Specifically, the light emitting part 322 and the space dividing part 324 are formed by heating the base substrate having the same plate shape as the first substrate 310 to a predetermined temperature and then molding the base substrate through a mold having a desired shape. A second substrate 320 may be obtained.

In the present embodiment, the longitudinal cross-section of the second substrate 320 has a form in which a plurality of semi-ellipses similar to trapezoids are continuously connected, as shown in FIG. 6. However, in contrast, the second substrate 320 may be formed so that the longitudinal section has various shapes such as a semicircle and a quadrangle.

The second substrate 320 having such a shape is coupled to the first substrate 310 through, for example, an adhesive means 330 such as fused lead glass. That is, the second substrate 320 and the first substrate 310 are bonded to each other by firing after the bonding means 330 is interposed between the second substrate 320 and the first substrate 310 to surround the edge portion. do. At this time, since the bonding means 330 is formed only at the edge portion between the second substrate 320 and the first substrate 310, the space dividing portion 324 is formed on the first substrate 310 by the pressure difference between the inside and the outside. Close contact. Specifically, a discharge gas for plasma discharge is injected into the plurality of discharge spaces 370 formed by the combination of the second substrate 320 and the first substrate 310. The gas pressure of the discharge gas is about 50 torr, and a pressure difference occurs as compared with the external atmospheric pressure of 760 torr. Due to the pressure difference between the inside and the outside, the space dividing unit 324 is in close contact with the first substrate 310, thereby forming a plurality of discharge spaces 370.

In addition, each of the space dividing portions 324 is connected to the adjacent discharge space 370, the connecting passage 326 formed to be spaced apart from the first substrate 310 by a predetermined distance when combined with the first substrate 310 ). At least one or more connection passages 326 are formed in each of the space dividing units 324, and are preferably alternately formed at one end or the other end in the longitudinal direction of the space dividing unit 324 adjacent to each other. That is, the connection passage 326 is formed at one end in the longitudinal direction of one of the space dividing portion 324 adjacent to each other, the other in the longitudinal direction in the other space dividing portion 324 It is formed at the end. Such a connection passage 326 may be obtained by less recession than the space dividing unit 324 in forming the second substrate 320. Therefore, the discharge gas injected into at least one discharge space 370 is moved to the other discharge space 370 through the connection passage 326, and eventually, the discharge gas is uniformly distributed in all the discharge spaces 370.

Meanwhile, the light source body 300 may include first and second fluorescent layers 340 and 350 and first and second substrates 310, which are formed on opposite surfaces of the first and second substrates 310 and 320, respectively. It further includes a reflective layer 360 formed between the first fluorescent layer 340. The first and second fluorescent layers 340 and 350 are excited by ultraviolet rays generated through plasma discharge to emit visible light. The reflective layer 360 reflects the visible light generated by the first and second fluorescent layers 340 and 350 toward the second substrate 320 to prevent the light from leaking to the first substrate 310.

In the present embodiment, the first and second electrodes 210 and 220 are preferably formed on the outer surface of the first substrate 310 having a flat plate shape, but may also be formed on the outer surface of the second substrate 320.

7 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention. In the present embodiment, the surface light source device has the same configuration as described with reference to Figs. 1 to 6, and the duplicated description thereof will be omitted.

Referring to FIG. 7, the liquid crystal display device 2000 according to the exemplary embodiment includes a surface light source device 1000, a storage container 600, a display unit 700, and an inverter 800.

The storage container 600 includes a bottom portion 610 and a plurality of sidewalls 620 extending from the edge of the bottom portion 610 to form the accommodation space for accommodating the surface light source device 1000. The plurality of sidewalls 620 extends from the edge of the bottom portion 610 to be in contact with four sides of the surface light source device 1000 that is vertically received and prevents the flow of the surface light source device 1000.

The display unit 700 includes a liquid crystal display panel 710 for displaying an image, data for providing a driving signal for driving the liquid crystal display panel 710, and gate printed circuit boards 720 and 730. The driving signals provided from the data and gate printed circuit boards 720 and 730 are transferred to the liquid crystal display panel 710 via a data tape carrier package (hereinafter referred to as TCP) 740 and a gate TCP 750. Is approved. Here, each of the data TCP 740 and the gate TCP 750 controls the driving signal to apply the driving signals provided from the data and the gate printed circuit boards 720 and 730 to the liquid crystal display panel 710 at an appropriate timing. And a data driver chip 742 and a gate driver chip 752.

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 such an 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 surface light source device 1500 in accordance with the arrangement change of the liquid crystal 716. The transmittance of light is changed to obtain an image of a desired gray scale.

The inverter 800 is disposed on the rear surface of the storage container 600 and generates a discharge voltage for driving the surface light source device 1000. The discharge voltage generated from the inverter 800 is applied to the first and second electrodes 210 and 220 of the surface light source device 1000 through the first and second power lines 810 and 820, respectively.

Meanwhile, the liquid crystal display device 2000 is fixed to fix the light diffusing member 900 and the liquid crystal display panel 710 disposed between the surface light source device 1000 and the liquid crystal display panel 710 to the storage container 600. It further includes a member 950.

The light diffusing member 900 diffuses the light emitted from the surface light source device 1000 and supplies light of uniform brightness to the liquid crystal display panel 710. The light diffusing member 900 is made of a plate-shaped diffusion plate having a predetermined thickness, and may further include a thin sheet-shaped diffusion sheet. Although not shown, the liquid crystal display device 2000 further includes a prism sheet disposed between the light diffusing member 900 and the liquid crystal display panel 710 to increase the front luminance of the light directed toward the liquid crystal display panel 710. can do.

The fixing member 950 is coupled to the storage container 600 while surrounding the edge of the liquid crystal display panel 710 to fix the liquid crystal display panel 710 on the light diffusion member 900. The fixing member 950 prevents the liquid crystal display panel 710 from being damaged by an external impact, and prevents the liquid crystal display panel 710 from being separated from the storage container 600.

According to such a surface light source device and a liquid crystal display device having the same, a decrease in luminance generated at the upper and lower ends by increasing the electrode widths of the first and second electrodes overlapping with the discharge spaces located at the upper and lower ends of the light source body. It is possible to prevent and improve luminance uniformity and display quality of emitted light.

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.

1 is an exploded perspective view showing a surface light source device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the surface light source device shown in FIG. 1.

3 is a plan view illustrating the first and second electrodes illustrated in FIG. 1.

4 is a plan view illustrating another example of the first and second electrodes illustrated in FIG. 3.

5 is a perspective view showing another embodiment of the light source body shown in FIG. 1.

6 is a cross-sectional view of the light source body shown in FIG. 5.

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

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

100: light source body 110: first substrate

120: second substrate 140: space partition member

210 and 220: first and second electrodes 600: storage container

710: liquid crystal display panel 800: inverter

900 light diffusing member 950 fixing member

1000: surface light source device 2000: liquid crystal display device

Claims (13)

A light source body having an internal space divided into a plurality of discharge spaces and generating light; The discharge spaces are formed on the outer surface of the light source body and are formed at both ends in the longitudinal direction of the discharge space so as to intersect the plurality of discharge spaces, and the electrode widths extending in parallel with the longitudinal direction of the discharge space overlap. Surface light source device comprising a first electrode and a second electrode formed differently according to. The surface light source device of claim 1, wherein the electrode width of each of the first and second electrodes increases as the distance from the center to the direction perpendicular to the longitudinal direction of the discharge space. The surface light source device of claim 2, wherein the first electrode and the second electrode are symmetrically formed. The method of claim 1, wherein the electrode width of each of the first and second electrodes is formed with a constant width from the center to the first point in a direction perpendicular to the longitudinal direction of the discharge space, gradually from the first point to the end The surface light source device characterized in that the larger. The method of claim 1, wherein the light source body A first substrate having a flat plate shape; A second substrate having the same shape as the first substrate and combined with the first substrate to form the internal space; And And a plurality of space dividing members disposed between the first substrate and the second substrate to divide the internal space into the plurality of discharge spaces. The method of claim 5, wherein the plurality of space dividing members are arranged side by side spaced apart from each other, and each of the space dividing member is at least one end of both ends in the longitudinal direction is spaced apart from the side wall of the light source body Surface light source device characterized in that. The method of claim 1, wherein the light source body A first substrate having a flat plate shape; And A light emitting part spaced apart from the first substrate and a space dividing part contacting with the first substrate to divide the internal space into the plurality of discharge spaces; A surface light source device comprising two substrates. The surface light source device of claim 7, wherein the first and second electrodes are formed on an outer surface of the first substrate. The surface light source device of claim 7, wherein the space dividing portion is spaced apart from the first substrate so as to connect the discharge spaces adjacent to each other. The method of claim 1, wherein the light source body A reflection layer formed on one surface of an inner surface of the light source body to reflect light generated in the inner space; And And a fluorescent layer formed on an inner surface of the light source body to generate visible light. A light source body having an internal space divided into a plurality of discharge spaces for the generation of light, and an electrode width respectively formed at both ends of the light source body to intersect the plurality of discharge spaces and extending in parallel with a length direction of the discharge space A surface light source device including first and second electrodes formed differently according to the discharge spaces overlapping each other; A storage container for storing the surface light source device; A liquid crystal display panel which displays an image using light emitted from the surface light source device; And And an inverter disposed on a rear surface of the storage container and configured to apply a discharge voltage to the first and second electrodes for driving the surface light source device. 12. The liquid crystal display device according to claim 11, wherein the electrode width of each of the first and second electrodes increases as the distance from the center to the direction perpendicular to the longitudinal direction of the discharge space. The method of claim 11, A light diffusion member disposed between the surface light source device and the liquid crystal display panel; And And a fixing member for fixing the liquid crystal display panel to the storage container.