KR20060023655A - Surface light source device and back light unit having the same - Google Patents

Abstract

The surface light source device includes a light source body in which discharge spaces into which discharge gas is injected are arranged in a zigzag form along a vertical direction, and an electrode for applying a voltage to the discharge gas. Since the light source body has a discharge space arranged in a zigzag form, the phenomenon that the partitions of the light source body act as a dark portion is suppressed as much as possible.

Description

Surface light source device and back light unit having the same {SURFACE LIGHT SOURCE DEVICE AND BACK LIGHT UNIT HAVING THE SAME}

1 and 2 are cross-sectional views showing conventional surface light source devices.

3 is a perspective view showing a surface light source device according to Embodiment 1 of the present invention.

4 is a cross-sectional view taken along line IVa-IVb of FIG. 3.

5 is a cross-sectional view showing a surface light source device according to a second embodiment of the present invention.

6 is an exploded perspective view showing a backlight unit according to a third embodiment of the present invention.

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

110: first substrate 111: first discharge space forming unit

112: first partition wall 120: second substrate

121: second discharge space forming portion 122: second partition wall portion

130: reflective film 141: first fluorescent layer

142 second fluorescent layer 150 electrode

160: auxiliary fluorescent layer S1, S2: discharge space

The present invention relates to a surface light source device and a backlight unit having the same, and more particularly, to a surface light source device for emitting light in the form of a plane, and a backlight unit having such a surface light source device as a light source.

In general, liquid crystals (LC) have both electrical and optical characteristics. The arrangement of the liquid crystal is changed in correspondence with the direction of the electric field by the electrical properties, and the transmittance of light is changed in response to the arrangement by the optical properties.

The liquid crystal display displays an image by using electrical and optical characteristics of the liquid crystal. Liquid crystal displays have the advantages of being very small in volume and light in weight compared to CRTs, etc. As a result, they are widely used in portable computers, communication devices, liquid crystal television receivers, and aerospace industries.

In order to control the liquid crystal, a liquid crystal display device requires a liquid crystal controlling part for controlling the liquid crystal and a light supplying part for supplying light to the liquid crystal.

The liquid crystal control part includes a pixel electrode disposed on the first substrate, a common electrode disposed on the second substrate, and a liquid crystal interposed between the pixel electrode and the common electrode. The pixel electrode is formed in plural in correspondence with the resolution, and the common electrode is made of one and facing the pixel electrode. A thin film transistor (TFT) is connected to each pixel electrode to apply a pixel voltage having a different level, and a reference voltage of the same level is applied to the common electrode. The pixel electrode and the common electrode are made of a transparent material having conductivity.

The light supply part supplies light to the liquid crystal of the liquid crystal control part. Light sequentially passes through the pixel electrode, the liquid crystal, and the common electrode. In this case, the display quality of the image passing through the liquid crystal is greatly influenced by the luminance and luminance uniformity of the light supply part. In general, the higher the luminance and the uniformity of the luminance, the better the display quality.

The light supply part of the conventional liquid crystal display device mainly uses a cold cathode fluorescent lamp (CCFL) having a rod shape or a light emitting diode (LED) having a dot shape. Cold cathode ray tube type lamp has a high brightness, long life, and has the advantage of having a very low heat generation compared to incandescent lamps. On the other hand, the light emitting diode has advantages of low power consumption and high brightness. However, the conventional cold cathode ray tube lamps or light emitting diodes have a disadvantage in that the luminance uniformity is weak.

Therefore, a light supply part having a cold cathode ray tube lamp or a light emitting diode as a light source may have an optical member such as a light guide panel (LGP), a diffusion member, and a prism sheet to increase luminance uniformity. (optical member) is included. As a result, a liquid crystal display using a cold cathode ray tube lamp or a light emitting diode has a problem in that the volume and weight of the optical member are greatly increased.

In order to solve this problem, a planar light source device has been proposed. An example of a conventional surface light source device is shown in FIG. 1 in a plan view.

Referring to FIG. 1, the conventional surface light source device includes a first substrate 1 and a second substrate 2 disposed on the first substrate 1. The second substrate 2 has integrally the partitions 3 facing the first substrate 1. The partition portions 3 form a plurality of discharge spaces 5 into which discharge gas is injected between the first and second substrates 1 and 2. An electrode 4 for applying a voltage to the discharge gas is provided on the upper surface of the second substrate 2.

In the surface light source device as described above, since the area for generating light is only the discharge space 5, the portion where the partition wall portion 3 is located serves as a dark field for reducing the luminance of the surface light source device. Therefore, various studies have been attempted to minimize the area occupied by the partition walls 3 in the entire discharge space. By this attempt, the conventional partition walls 3 have a width of approximately 1 mm or less.

On the other hand, the first problem to be solved to improve the brightness of the surface light source device is to prevent the current drift phenomenon. The current drift phenomenon refers to a phenomenon in which a potential difference is generated between adjacent discharge spaces, so that a current in the discharge space in which a relatively high voltage is formed is concentrated in a discharge space having a low voltage. This drift phenomenon has been a major factor for lowering the luminance of the surface light source device.

However, as described above, as the partition walls have a width of 1 mm or less, the distance between neighboring discharge spaces is also reduced. As a result, parasitic capacitors are formed in the partition portions, and current often flows through the parasitic capacitors into the adjacent discharge space. Therefore, the current drift phenomenon is intensified, and a problem arises in that the luminance of the surface light source device is lowered as a whole.

In order to solve the above problem, the applicant has filed a patent application (application number 2004-40195) of the surface light source device shown in FIG.

Referring to FIG. 2, the surface light source device includes a first substrate 10 and a second substrate 20 disposed on the first substrate 10. The second substrate 20 is connected to the first substrate 10 by connecting the discharge space forming parts 21 and the discharge space forming parts 21 together with the first substrate 10 to form the discharge space 50. The partition walls 22 are joined to each other via the frit 30. In particular, the partition wall portion 22 has a width of about 3 to 5 mm, so that the distance between the discharge spaces 50 is wider than that of the surface light source device shown in FIG. The electrode 40 is provided on the upper surface of the second substrate 20.

In the surface light source device shown in FIG. 2, the width of the partition wall portion 22 is increased by about 4 times from the conventional 1 mm, so that parasitic capacitors are not formed in the partition wall portion 22. Therefore, the phenomenon that a current flows through the partition part 22 is prevented, and the brightness of a surface light source device improves as a whole. However, since the width of the partition wall portion 22 is wide, there is a disadvantage that the area of the dark portion increases.

The present invention provides a surface light source device that can have improved brightness by reducing the dark area as much as possible.

In addition, the present invention provides a backlight unit having the surface light source device as a light source.

According to an aspect of the present invention, a surface light source device includes a light source body in which discharge spaces into which discharge gas is injected are arranged in a zigzag shape along a vertical direction, and an electrode for applying a voltage to the discharge gas.

According to an embodiment of the present invention, the light source body includes a first substrate having first discharge space forming portions, and first partition wall portions connecting the first discharge space forming portions to each other, and a first substrate disposed above the first partition wall portions. And a second substrate having second discharge space forming portions, and a second partition wall portion formed on top of the first discharge space forming portions while connecting the second discharge space forming portions to each other. Both sides of the upper end of the first partition wall part may contact the lower end of the second partition wall part and the lower end of another second partition wall part adjacent to the second partition wall part. Alternatively, an upper end side of the first partition wall part may contact the lower end of the second partition wall part, and the other upper end side of the first partition wall part may be spaced apart from a lower end of another second partition wall part adjacent to the second partition wall part.

According to another aspect of the present invention, a backlight unit includes a surface light source device and an upper and lower case for housing the surface light source device. The surface light source device includes a light source body having discharge spaces in which discharge gas is injected and arranged in a zigzag shape along the vertical direction, and an electrode for applying a voltage to the discharge gas. An optical sheet is interposed between the surface light source device and the upper case. The inverter applies a discharge voltage to the electrode for driving the surface light source device.

According to the present invention as described above, discharge space forming parts are provided in each of the first substrate and the second substrate, and each of the discharge space forming parts is arranged to correspond to the partition walls, so that the phenomenon of the partitions acting as a dark part is caused. Suppressed as much as possible.

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

Example 1

3 is a perspective view illustrating a surface light source device according to Embodiment 1 of the present invention, and FIG. 4 is a cross-sectional view taken along line IVa-IVb of FIG. 3.

3 and 4, the surface light source device 100 according to the present embodiment includes a light source body having a plurality of discharge spaces into which discharge gas is injected, and an electrode 150 for applying a voltage to the discharge gas. do. Mercury gas, argon gas, neon gas, xenon gas, and the like may be used as the discharge gas.

The light source body includes a first substrate 110 and a second substrate 120 disposed on the first substrate 110. The first and second substrates 110 and 120 are made of a glass material that transmits visible light and blocks ultraviolet rays. The second substrate 120 is an exit surface from which light generated in the discharge space is emitted.

The first substrate 110 includes first discharge space forming parts 111 for forming first discharge spaces S1 and first partition walls 112 for connecting the first discharge space forming parts 111 to each other. do. The first discharge space forming portions 111 are arranged in parallel with each other. In the present embodiment, the first discharge space forming portions 111 have a substantially trapezoidal shape. In another embodiment, the first discharge space forming portions 111 may have a rectangular, semicircular, triangular, or arcuate shape. The first partition walls 112 have a thin and long flat plate shape that connects both lower ends of the first discharge space forming units 111 to each other. In particular, the first partition walls 112 have a width of about 3 to 5 mm. In addition, in the present embodiment, the first discharge space forming portions 111 have a width substantially the same as the width of the first partition portion 112 or narrower than the width of the first partition portion 112.

The second substrate 120 includes second discharge space forming portions 121 that form second discharge spaces S2, and second partition wall portions 122 that connect the first discharge space forming portions 121 to each other. do. That is, the second substrate 120 has a shape substantially the same as that in which the first substrate 110 is inverted to 180 Hz. Therefore, the second discharge space forming unit 121 has a shape substantially the same as the arch shape of the first discharge space forming unit 111. Therefore, unlike the first substrate 110, the second substrate 120 does not need to be manufactured separately, and the first substrate 110 may be inverted and used as the second substrate 120.

The second discharge space forming parts 121 are positioned on the first partition walls 112 to form arcuate second discharge spaces S2 together with the first partition wall 112. The second partition walls 122 are positioned on the first discharge space forming parts 111 to form a first discharge space S1 together with the first discharge space forming parts 111. That is, both upper ends of the first partition wall part 112 are in contact with the lower end of the second partition wall part 122 and the lower end of another second partition wall part 122 adjacent to the second partition wall part 122, and are separated from each other. Formed first and second discharge spaces S1 and S2. Therefore, since the second discharge spaces S2 are disposed between the first discharge spaces S1, the discharge spaces are arranged in a zigzag form along the vertical direction.

Meanwhile, as described above, since the widths of the first and second partition walls 112 and 122 are substantially the same as or wider than the widths of the first and second discharge space forming portions 111 and 121, the first discharge space S1. ), Each of the second discharge spaces S2 and also the first and second discharge spaces S1 and S2 are isolated from each other.

A first communication path (not shown) for communicating neighboring first discharge spaces S1 and a neighboring first for vacuum evacuation and discharge gas injection of the first and second discharge spaces S1 and S2 isolated from each other. A second communication path 123 for communicating the two discharge spaces S2 is provided. The first communication path is formed to have a structure protruding from the bottom surface of the first partition wall part 112 to communicate the first discharge spaces S1 located at both sides of the first partition wall part 112 with each other. The second communication path 123 is formed to have a structure protruding from the upper surface of the second partition wall part 122 to communicate the second discharge spaces S2 located on both sides of the second partition wall part 122 with each other. In particular, the first communication path and the second communication path 123 are formed to have lengths of the first and second discharge space forming parts 111 and 121 so as to suppress a current flowing between neighboring discharge spaces S1 and S2. It is preferable that it is a diagonal shape which makes a predetermined acute angle with a direction. In another embodiment, the first communication path and the second communication path 123 may be substantially orthogonal to the longitudinal direction of the first and second discharge space forming parts 111 and 121.

Among the light generated in the first and second discharge spaces S1 and S2, the reflective film 130 for reflecting the light directed toward the first substrate 110 toward the second substrate 120 includes the first substrate 110. It is formed on the upper surface of the thickness of about 120㎛. The first fluorescent layer 141 is formed on the reflective film 130 with a thickness of about 30 μm. The second fluorescent layer 142 is formed on the bottom surface of the second substrate 120.                     

According to this embodiment, since the 1st discharge space S1 is located also under the 2nd partition wall part 122, it is suppressed that the 2nd partition wall part 122 acts as a dark part of a surface light source device. However, in order to further suppress the second barrier rib portion 122 from acting as a dark portion, the auxiliary fluorescent layer 160 may be formed on the upper surface of the second barrier rib portion 122.

On the other hand, the electrode 150 for applying a voltage to the discharge gas in the first and second discharge space (S1, S2) is formed along both edges of the upper surface of the first and second substrate (110,120). The electrode 150 includes a material having excellent conductivity, for example, copper (Cu), nickel (Ni), silver (Ag), gold (Au), aluminum (Al), chromium (Cr), and the like. The electrode 140 may be formed by attaching a conductive tape made of the above material to the outer circumferential surface of the light source body or coating the metal powder of the above material on the outer circumferential surface of the light source body.

Example 2

5 is a cross-sectional view showing a surface light source device according to a second embodiment of the present invention.

Referring to FIG. 5, the surface light source device 200 according to the present exemplary embodiment includes a light source body having a plurality of discharge spaces into which a discharge gas is injected, and an electrode 250 for applying a voltage to the discharge gas.

The light source body includes a first substrate 210 and a second substrate 220 disposed on the first substrate 210. The first substrate 210 includes first discharge space forming parts 211 forming the first discharge spaces S1 and first partition wall parts 212 connecting the first discharge space forming parts 211 to each other. do. In the present embodiment, the first discharge space forming portions 211 may have a width wider than that of the first partition wall portion 212.

The second substrate 220 includes second discharge space forming portions 221 forming second discharge spaces S2 and second partition wall portions 222 connecting the second discharge space forming portions 221 to each other. do. The second discharge space forming portions 221 are positioned on the first partition walls 212, and the second partition wall portions 222 are positioned on the first discharge space forming portions 211.

In particular, an upper end side of the first partition wall part 212 is in contact with a lower end of the second partition wall part 222. On the other hand, the other side of the upper end of the first partition wall portion 212 is spaced apart from the lower end of the second partition wall portion 222 adjacent to the second partition wall portion 222. Accordingly, the first and second discharge space forming portions 211 and 221 and the first and second partition walls 212 and 222 together form discharge spaces S isolated from each other. The discharge spaces S have a shape substantially similar to the shape of the sum of the first and second discharge spaces S1 and S2 of the first embodiment.

In order to communicate the discharge spaces S isolated from each other, a communication path (not shown) may be formed in the first substrate 210, the second substrate 220, or both the first and second substrates 210 and 220. have.

The reflective film 230 is formed on the upper surface of the first substrate 210. The first fluorescent layer 241 is formed on the reflective film 230. The second fluorescent layer 242 is formed on the bottom surface of the second substrate 20. The auxiliary fluorescent layer 260 may be formed on the upper surface of the second partition wall part 222. Meanwhile, the electrode 250 is formed along both edges of the upper surfaces of the first and second substrates 210 and 220.

Example 3

6 is an exploded perspective view showing a backlight unit according to a third embodiment of the present invention.

Referring to FIG. 6, the backlight unit 1000 according to the present exemplary embodiment includes the surface light source device 100, the upper and lower cases 700 and 800, the optical sheet 900, and the inverter 850 according to the first embodiment. do.

Since the surface light source device 100 has substantially the same configuration as the surface light source device shown in FIG. 3, the description of the surface light source device 100 will be omitted. Meanwhile, the surface light source device according to the second embodiment shown in FIG. 5 may be employed in the backlight unit 1000.

The lower case 800 includes a bottom portion 810 and a plurality of sidewalls 820 extending from the edge of the bottom portion 810 to form an accommodation space for accommodating the surface light source device 100. The surface light source device 100 is accommodated in the storage space of the lower case 800.

The inverter 850 is disposed on the rear surface of the lower case 800 and generates a discharge voltage for driving the surface light source device 100. The discharge voltage generated from the inverter 850 is applied to the electrodes 150 of the surface light source device 100 through the first and second power lines 852 and 854, respectively.

The optical sheet 900 may be formed of a diffusion plate (not shown) for uniformly diffusing the light emitted from the surface light source device 100 and a prism sheet (not shown) for imparting straightness to the diffused light.

The upper case 700 is coupled to the lower case 800 to support the surface light source device 100 and the optical sheet 900. The upper case 700 prevents the surface light source device 100 from being separated from the lower case 800.                     

Meanwhile, a liquid crystal display panel (not shown) for displaying an image may be disposed on the upper case 700.

According to the present invention as described above, since the discharge spaces are arranged in a zigzag form along the vertical direction, it is suppressed that the partition portion acts as a dark portion. Therefore, the luminance of the surface light source device can be greatly improved.

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 (10)

A light source body into which discharge gas is injected and having discharge spaces arranged in a zigzag shape along the vertical direction; And And an electrode for applying a voltage to the discharge gas. The method of claim 1, wherein the light source body A first substrate having first discharge space forming portions and first partition wall portions connecting the first discharge space forming portions to each other; And And a second substrate having second discharge space forming portions disposed on the first barrier rib portions, and a second barrier portion disposed on the first discharge space forming portions while connecting the second discharge space forming portions to each other. , Both sides of the upper end of the first partition wall part may contact the lower end of the second partition wall part and the lower end of another second partition wall part adjacent to the second partition wall part to form first and second discharge spaces arranged up and down while being separated from each other. Surface light source device, characterized in that. 3. The surface light source device according to claim 2, wherein communication paths for communicating the isolated first and second discharge spaces are formed in the first and second partition walls. The surface light source device of claim 3, wherein the communication paths are inclined with respect to the length direction of the first and second discharge space forming parts. The surface light source device of claim 2, wherein the first and second partitions have a width that is wider or substantially the same as that of the first and second discharge space forming portions. The surface light source device of claim 2, further comprising a first fluorescent layer formed on an upper surface of the first substrate, and a second fluorescent layer formed on a bottom surface of the second substrate. 7. The surface light source device according to claim 6, further comprising a reflective film interposed between the first fluorescent layer and the first substrate. The surface light source device of claim 6, further comprising an auxiliary fluorescent layer formed on upper surfaces of the second partition walls. The method of claim 1, wherein the light source body A first substrate having first discharge space forming portions and first partition wall portions connecting the first discharge space forming portions to each other; And And a second substrate having second discharge space forming portions disposed on the first barrier rib portions, and a second barrier portion disposed on the first discharge space forming portions while connecting the second discharge space forming portions to each other. , One upper end of the first partition wall part is in contact with a lower end of the second partition wall part, and the other upper end of the first partition wall part is spaced apart from a lower end of another second partition wall part adjacent to the second partition wall part to form discharge spaces that are isolated from each other. Surface light source device characterized in that. A surface light source device including a light source body into which discharge gas is injected and having discharge spaces arranged in a zigzag shape along the vertical direction, and an electrode for applying a voltage to the discharge gas; Upper and lower cases accommodating the surface light source device; An optical sheet interposed between the surface light source device and the upper case; And And an inverter for applying a discharge voltage for driving the surface light source device to the electrode.

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