KR20070073058A - Surface light source device and back light unit having the same - Google Patents

Abstract

A surface light source device and a backlight unit having the same are provided to offer the reflection function and the fluorescent function only by using a single mixing layer. The second substrate(112) is arranged at the upper portion of the first substrate(111). Partitions(120) are arranged between the first and second substrates and form plural discharge spaces for receiving the discharge gas. An electrode is equipped to the first and second substrates and applies the voltage to the discharge gas. A mixing layer(180) is formed on the surface of the first substrate by mixing the reflection materials with fluorescent materials. The fluorescent layer is formed on the base surface of the second substrate. The thickness of the mixing layer is below 30 micrometer and the thickness of the fluorescent layer is below 15 micrometer. The partitions are integrally formed to the second substrate.

Description

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

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

FIG. 2 is a cross-sectional view taken along the line II-II 'of FIG. 1.

FIG. 3 is an enlarged cross-sectional view of part III of FIG. 2.

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

FIG. 5 is a cross-sectional view taken along the line VV ′ of FIG. 4.

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-

111: first substrate 112: second substrate

120: partition 130: sealing member

140: discharge space 150: electrode

160: reflective layer 171, 172: fluorescent layer

180: mixed layer 181: reflective material

182: fluorescent material

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 an advantage of high luminance. However, the conventional cold cathode ray tube lamps or light emitting diodes have a disadvantage in that the luminance uniformity is weak.

Accordingly, the light supply part having the cold cathode ray tube type lamp or the light emitting diode as a light source is used to improve optical uniformity such as a light guide panel (LGP), a diffusion member, a prism sheet, and the like. It includes an optical member. 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. The conventional surface light source device can be divided into a partition partition type and a partition wall type.

The conventional partition wall type surface light source device includes a first substrate, a second substrate disposed on the first substrate, and a sealing member disposed between edges of the first and second substrates to define an internal space. The partition walls are arranged in the inner space, thereby partitioning the inner space into a plurality of discharge spaces into which the discharge gas containing mercury gas is injected. The reflective layer is formed on the first substrate. The first fluorescent layer is formed on the reflective layer. The second fluorescent layer is formed on the underside of the second substrate. Electrodes for applying a voltage to the discharge gas are formed along the outer edges of both edges of the first and second substrates.

On the other hand, the conventional partition integrated surface light source device includes a first substrate and a second substrate disposed on the first substrate. The second substrate has a plurality of partitions integrally. The partition portions are opposed to the first substrate, whereby a plurality of discharge spaces into which the discharge gas is injected are formed. The outermost partition walls are bonded to the first substrate via a sealing frit. The reflective layer is formed on the first substrate. The first fluorescent layer is formed on the reflective layer. The second fluorescent layer is formed on the underside of the second substrate. An electrode for applying a voltage to the discharge gas surrounds the outer peripheral surfaces of the first and second substrates.

In the conventional surface light source devices as described above, the reflective layer and the fluorescent layer are separately provided on the first substrate. In particular, in order to give the reflective layer the desired reflective function, the thickness of the reflective layer should be 60 μm or more. In addition, in consideration of shortening the life of the fluorescent layer exposed to mercury in accordance with the long-term operation of the surface light source device, the thickness of the fluorescent layer should be 40 μm or more. Due to the separate reflective layer and the fluorescent layer having a thick thickness, there is a problem that the thickness of the surface light source device is too thick.

The present invention provides a surface light source device having a thin thickness without decreasing luminance.

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

The surface light source device according to one aspect of the present invention includes a first substrate and a second substrate disposed on the first substrate. The partition walls form a plurality of discharge spaces into which discharge gas is injected between the first and second substrates. Electrodes for applying a voltage to the discharge gas are provided on the first and second substrates. A mixed layer in which the reflective material and the fluorescent material are mixed is formed on the surface of the first substrate. A fluorescent layer is formed on the underside of the second substrate.

According to one embodiment of the invention, a reflective layer may be interposed between the mixed layer and the first substrate.

According to another embodiment of the present invention, a fluorescent layer may be formed on the mixed layer.

According to another embodiment of the present invention, the partitions may be integrally formed on the second substrate.

According to another aspect of the present invention, a backlight unit includes a surface light source device, a case accommodating the surface light source device, an optical sheet interposed between the surface light source device and the case, and a discharge voltage for driving the surface light source device. It includes an inverter to apply. The surface light source device includes barrier ribs forming a first substrate, a second substrate disposed on the first substrate, and a plurality of discharge spaces into which discharge gas is injected between the first and second substrates. An electrode provided on a second substrate to apply a voltage to the discharge gas, a mixed layer formed on a surface of the first substrate and mixed with a reflective material and a fluorescent material, and a fluorescent layer formed on a bottom surface of the second substrate; .

According to the present invention as described above, the single mixed layer in which the reflective material and the fluorescent material are mixed simultaneously performs the reflective function and the fluorescent function. Therefore, since the reflection function and the fluorescence function can be provided to the surface light source device with only a single mixed layer, the thickness of the surface light source device can be reduced.

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

Example 1

1 is a perspective view showing a surface light source device according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line II-II 'of FIG. 1, and FIG. 3 is an enlarged view of part III of FIG. It is a cross section.

1 and 2, the surface light source device 100 according to the present embodiment includes a light source body having an internal space into which a discharge gas is injected, and an electrode 150 for applying a voltage to the discharge gas. Meanwhile, mercury gas, argon gas, neon gas, xenon gas, or the like may be used as the discharge gas.

The surface light source device 100 according to the present embodiment is a partition wall separation type. Accordingly, the light source body is disposed between the edges of the first substrate 111, the second substrate 112 disposed on the first substrate 111, and the first and second substrates 111 and 112 to define an internal space. Sealing member 130, and partition walls 120 dividing an inner space into a plurality of discharge spaces 140.

The first and second substrates 111 and 112 are made of a glass material that transmits visible light and blocks ultraviolet rays. The second substrate 112 is an emission surface from which light generated in the discharge space 140 is emitted.

The partition walls 120 are arranged parallel to the inner space along the first direction to partition the inner space into a plurality of discharge spaces 140 having a stripe shape. Lower surfaces of the partition walls 120 may face the first substrate 111 and the upper surface may face the second substrate 112. In order to inject the discharge gas into each of the discharge spaces 140, the partition walls 120 may be arranged in a meandering structure or a communication path (not shown) may be formed in the partition walls 120.

The electrode 150 includes a first electrode 152 formed on the bottom surface of the first substrate 111, and a second electrode 154 formed on the top surface of the second substrate 112. In particular, the first and second electrodes 152 and 154 are disposed at both edges of the first and second substrates 111 and 112 along a second direction substantially perpendicular to the first direction. Meanwhile, the electrode 150 may include a conductive tape or a conductive paste.

The reflective layer 160 is formed on the surface of the first substrate 111. The reflective layer 160 reflects the light directed toward the first substrate 111 among the light generated in the discharge space 140 toward the second substrate 112. The material of the reflective layer 160 is BaSO ₄ , TiO ₂ , SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , BiTiO ₃ Etc. can be mentioned. In particular, the reflective layer 160 has a thickness of 50 μm or less. That is, the conventional reflective layer has a thickness of 60 μm or more, while the reflective layer 160 of the present invention has a thickness of 50 μm or less.

The mixed layer 180 is formed on the reflective layer 160. As shown in detail in FIG. 3, the mixed layer 180 has a slurry in which the reflective material 181 and the fluorescent material 182 are mixed. Therefore, the mixed layer 180 has a reflection function and a fluorescent function at the same time. The mixed layer 180 having these functions has a thickness of 30 μm or less.

The first fluorescent layer 171 excited by the ultraviolet rays generated from the discharge gas to which the voltage is applied is formed on the mixed layer 180. Here, the first fluorescent layer 171 has a thickness of 15 μm or less. That is, the conventional first fluorescent layer has a thickness of 40 μm or more, while the first fluorescent layer 171 of the present invention has a thickness of 15 μm or less.

Here, the total thickness of the conventional reflective layer and the first fluorescent layer is 100 μm or more, while the total thickness of the reflective layer 160, the mixed layer 180, and the first fluorescent layer 171 of the present invention is 95 μm or less. Therefore, the thicknesses of the films formed on the first substrate 111 can be reduced by at least 5 μm or less than in the related art. In particular, since the reflective material 181 of the mixed layer 180 compensates for the insufficient reflection function of the reflective layer 160 of the present invention having a thickness thinner than that of the conventional reflective layer, the reflective function of the surface light source device 100 is maintained as it is. Can be. In addition, since the fluorescent material 182 of the mixed layer 180 compensates for the insufficient fluorescence function of the first fluorescent layer 171 of the present invention having a thickness thinner than that of the conventional first fluorescent layer, the surface light source device 100 ) Can also be maintained. As a result, even if the thickness of the films formed on the first substrate 111 is reduced, the luminance of the surface light source device 100 does not decrease.

The second fluorescent layer 172 having the same function as the first fluorescent layer 171 is formed on the bottom surface of the second substrate 112.

Meanwhile, in the present exemplary embodiment, the first fluorescent layer 171 and the reflective layer 160 are disposed on the upper and lower portions of the mixed layer 180, but the mixed layer 180 is sufficiently reflective and fluorescent. The first fluorescent layer 171 and the reflective layer 160 may be omitted.

Example 2

4 is a perspective view illustrating a surface light source device according to a third exemplary embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along the line VV ′ of FIG. 4.

4 and 5, the surface light source device 200 according to the present exemplary embodiment includes a light source body having an internal space into which discharge gas is injected, and an electrode 250 for applying a voltage to the discharge gas.

The surface light source device 200 according to the present embodiment is a partition wall integrated type. Thus, the light source body includes a first substrate 211 and a second substrate 212 disposed on the first substrate 211 and having the partition portions 220 integrally. The partition walls 220 arranged along the first direction are opposed to the first substrate 211 to form a plurality of discharge spaces 240 having a substantially arch shape. In order to inject the discharge gas into each of the discharge spaces 240, the partition walls 220 may be arranged in a meandering structure, or a communication path 225 may be formed in the partition walls 220. In particular, the communication path 225 may be formed in a diagonal or S-shape on the partition wall portion 220. On the other hand, the partition wall portion 220 according to the present embodiment has a width of about 1 to 5mm.

The electrodes 250 are arranged along both edges of the light source body 210 along a second direction substantially perpendicular to the first direction. The electrode 250 includes a first electrode 252 formed on the bottom surface of the first substrate 211, and a second electrode 254 formed on the top surface of the second substrate 212.

The reflective layer 260 is formed on the surface of the first substrate 211. Aluminum oxide may be used as the material of the reflective layer 260. In particular, the reflective layer 260 has a thickness of 50 μm or less.

The mixed layer 280 is formed on the reflective layer 260. Since the mixed layer 280 is substantially the same as the mixed layer 180 of the first embodiment, it will not be repeated here. Therefore, the mixed layer 280 has a reflection function and a fluorescent function at the same time. The mixed layer 280 having these functions has a thickness of 30 μm or less.

A first fluorescent layer 271 is excited on the mixed layer 280 that is excited by ultraviolet rays generated from the discharge gas to which a voltage is applied. The first fluorescent layer 271 has a thickness of 15 μm or less. A second fluorescent layer 272 having the same function as the first fluorescent layer 271 is formed on the bottom surface of the second substrate 212.

Meanwhile, in the present exemplary embodiment, the first fluorescent layer 271 and the reflective layer 260 are disposed on the upper and lower portions of the mixed layer 280, but the mixed layer 280 has a sufficiently reflective function and a fluorescent function. The first fluorescent layer 271 and the reflective layer 260 may be omitted.

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 200, the upper and lower cases 1100 and 1200, the optical sheet 900, and the inverter 1300 according to the third exemplary embodiment. do.

Since the surface light source device 200 has substantially the same configuration as the surface light source device shown in FIG. 4, the description of the surface light source device 200 will be omitted. Meanwhile, the surface light source devices according to the other embodiments described above may be employed in the backlight unit 1000.

The lower case 1200 includes a bottom portion 1210 and a plurality of sidewalls 1220 extending to form an accommodation space from an edge of the bottom portion 1210 for accommodating the surface light source device 200. The surface light source device 200 is accommodated in the storage space of the lower case 1200.

The inverter 1300 is disposed on the rear surface of the lower case 1200 and generates a discharge voltage for driving the surface light source device 200. The discharge voltage generated from the inverter 1300 is applied to the electrodes 250 of the surface light source device 200 through the first and second power lines 1352 and 1354, 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 200, and a prism sheet (not shown) for imparting straightness to the diffused light.

The upper case 1100 is coupled to the lower case 1200 to support the surface light source device 200 and the optical sheet 900. The upper case 1100 prevents the surface light source device 200 from being separated from the lower case 1200.

Meanwhile, a liquid crystal display panel (not shown) for displaying an image may be disposed on the upper case 1100.

As described above, according to the present invention, the single mixed layer in which the reflective material and the fluorescent material are mixed simultaneously performs the reflective function and the fluorescent function. Therefore, since the reflection function and the fluorescence function can be provided to the surface light source device using only a single mixed layer, the thickness of the surface light source device can be reduced while preventing the luminance from decreasing.

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 first substrate; A second substrate disposed on the first substrate; Barrier ribs for forming a plurality of discharge spaces into which discharge gas is injected between the first and second substrates; Electrodes provided on the first and second substrates to apply a voltage to the discharge gas; A mixed layer formed on a surface of the first substrate and mixed with a reflective material and a fluorescent material; And And a fluorescent layer formed on the bottom surface of the second substrate. The surface light source device of claim 1, wherein the reflective material comprises any one selected from the group consisting of BaSO ₄ , TiO ₂ , SiO ₂ , B ₂ O ₃ , Al ₂ O _3, and BiTiO ₃ . The surface light source device according to claim 1, wherein the thickness of the mixed layer is 30 m or less. The surface light source device according to claim 1, wherein the fluorescent layer has a thickness of 15 µm or less. The surface light source device of claim 1, further comprising a reflective layer interposed between the mixed layer and the first substrate. 6. The surface light source device according to claim 5, wherein the reflective layer has a thickness of 50 m or less. The surface light source device of claim 1, further comprising a fluorescent layer formed on the mixed layer. 8. The surface light source device according to claim 7, wherein the fluorescent layer has a thickness of 15 µm or less. The surface light source device of claim 1, wherein the barrier ribs are integrally formed on the second substrate. Barrier ribs forming a first substrate, a second substrate disposed on the first substrate, a plurality of discharge spaces in which discharge gas is injected between the first and second substrates, and the first and second substrates. A surface light source device including an electrode provided at an electrode to apply a voltage to the discharge gas, a mixed layer formed on a surface of the first substrate and a reflective material and a fluorescent material mixed therein, and a fluorescent layer formed on a bottom surface of the second substrate ; A case accommodating the surface light source device; An optical sheet interposed between the surface light source device and the case; And And an inverter for applying a discharge voltage for driving the surface light source device to the electrode. The backlight unit of claim 10, wherein the reflective material comprises any one selected from the group consisting of BaSO ₄ , TiO ₂ , SiO ₂ , B ₂ O ₃ , Al ₂ O _3, and BiTiO ₃ .

Images