KR20060120768A - 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 significantly improve the light emitting efficiency, by disposing electrodes within a light source body to directly apply a voltage to a discharge gas. A surface light source device(100) comprises a light source body(110). Barriers(130) are formed in the light source body to define a plurality of discharge spaces(120), into which a discharge gas is injected. The barriers have widths of 3 to 5 millimeters. Inner electrodes(150) are disposed within the light source body for applying a voltage to the discharge gas, wherein each of the inner electrodes has protrusions(157). The inner electrodes have thicknesses of 0.005 to 0.5 millimeters.

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 plan view showing a conventional surface light source device.

FIG. 2 is a cross-sectional view taken along line IIa-IIb of FIG. 1.

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

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

FIG. 5 is a plan view illustrating a surface light source device having a protrusion having a shape different from that of the protrusion of FIG. 3.

FIG. 6 is a plan view illustrating a surface light source device having a protrusion having a shape different from that of the protrusion of FIG. 3.

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

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

110: light source body 111: first substrate

112: second substrate 130: internal electrode

132: protective layer

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.

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. 1 is a plan view showing a conventional surface light source device, Figure 2 is a cross-sectional view taken along the line IIa-IIb of FIG.

1 and 2, a conventional surface light source device includes a light source body 10 and an external electrode 30. The light source body 10 includes a first substrate 11 and a second substrate 12 disposed on the first substrate 11. The second substrate 12 has a plurality of partitions 13 integrally. The partition portions 13 abut against the first substrate 11 to form a plurality of discharge spaces 20 into which the discharge gas is injected. In particular, in order to suppress occurrence of current drift between the discharge spaces 20 through the partition 13, the partition 13 has a width of about 4 mm. A communication path 40 for communicating the discharge spaces 20 is formed on the partition 13. The external electrode 30 for applying a voltage to the discharge gas surrounds the outer circumferential surfaces of the first and second substrates 11 and 12.

The conventional surface light source device as described above has an external electrode 30 for voltage application. Therefore, the voltage is not directly applied to the discharge gas but is applied to the discharge gas via the light source body 10. For this reason, the conventional surface light source device has a problem that the generation efficiency of plasma in the discharge space 20 is low.

The present invention provides a surface light source device having an improved luminous efficiency by allowing a voltage to be directly applied to the discharge gas.

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

According to one aspect of the invention, the surface light source device includes a light source body having partition walls of 3 to 5 mm in width defining a plurality of discharge spaces into which the discharge gas is injected. An internal electrode for applying a voltage to the discharge gas is disposed inside the light source body. Protrusions are formed in the inner electrode.

According to another aspect of the present invention, the backlight unit includes a surface light source device, an upper and lower case for housing the surface light source device, an optical sheet interposed between the surface light source device and the upper case, and a discharge voltage for driving the surface light source device. And an inverter applied to the light source device. The surface light source device has a light source body having partition portions having a width of 3 to 5 mm defining a plurality of discharge spaces into which discharge gas is injected, and an interior disposed inside the light source body for applying a voltage to the discharge gas and having protrusions. An electrode.

According to the present invention as described above, an electrode having a protrusion is disposed inside the light source body, whereby a voltage is directly applied to the discharge gas. Therefore, the luminous efficiency of the surface light source device is improved.

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

Example 1

3 is a plan 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 110 having an internal space 120 into which discharge gas is injected, and an internal electrode for applying a voltage to the discharge gas. And 150. Meanwhile, mercury gas, argon gas, neon gas, xenon gas, or the like may be used as the discharge gas.

The light source body 110 is disposed between 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, so that the discharge gas is formed. A sealing member 120 defining an internal space to be injected, partition walls 130 arranged in the internal space to partition the internal space into a plurality of discharge spaces 120, and an internal electrode for applying a voltage to the discharge gas ( 150).

Alternatively, the light source body may include a first substrate, a second substrate disposed on the first substrate and integrally having partition walls. The partition portions are abutted on the first substrate to form a plurality of discharge spaces into which the discharge gas is injected. The outermost partitions are joined to the first substrate via the sealing frit. The partition portions are arranged in parallel along the first direction. In addition, communication paths are formed on the surfaces of the partition walls in order to communicate the discharge spaces with each other. The communication path may be formed along a second direction that is inclined to form a predetermined acute angle with the first direction or substantially perpendicular to the first direction.

The partitions 130 are arranged in parallel along the first direction. According to the present embodiment, in order to communicate the discharge spaces 120 with each other, a communication path 132 is formed in the partition wall 130. Alternatively, the partition wall 130 may be arranged in a meandering structure to communicate the respective discharge spaces 120. In particular, the barrier ribs 130 have a width of about 3 to 5 mm in order to suppress a phenomenon in which current flows between neighboring discharge spaces 120 through the barrier ribs 130.

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 is emitted. The first protective layer 171 is formed on the first substrate 111, and the second protective layer 172 is formed on the bottom surface of the second substrate 112.

The internal electrode 150 is disposed along a second direction substantially perpendicular to the first direction at both inner edges of the light source body 110. The internal electrode 150 is disposed on the first substrate 111. Since the internal electrode 150 is disposed inside the light source body 110, a voltage is directly applied to the discharge gas. Therefore, the luminous efficiency of the surface light source device 100 can be improved as much as possible.

Alternatively, the internal electrode 150 may be disposed on the bottom surface of the second substrate 112. In addition, the internal electrode 150 may include a first electrode disposed on the first substrate 111 and a second electrode disposed on the bottom surface of the second substrate 112.

Protrusions 157 are formed in the internal electrode 150. The protrusion 157 has a substantially rectangular cross-sectional shape. The protrusion 157 enters into the discharge spaces 120. Alternatively, as shown in FIG. 5 and FIG. 6, a triangular cross-sectional protrusion 157a or a semicircular cross-sectional protrusion 157b may be provided. Since the area of the internal electrode 150 is further extended by the protrusion 157, the discharge efficiency is further improved. Therefore, the luminance of the surface light source device can be further improved.

Examples of the material of the internal electrode 150 include nickel (Ni), copper (Cu), silver (Ag), and the like. In addition, the internal electrode 150 has a thickness of approximately 0.005 to 0.5 mm. On the other hand, the internal electrode 150 may be formed of a metal thin film or by applying a conductive paste.

In addition, the protective layer 152 is preferably formed on the outer surface of the inner electrode 150 to suppress the oxidation of the inner electrode 150. The protective layer 152 may be a dielectric film such as a silicon oxide film. When the protective layer 152 is a dielectric film, the protective layer 152 serves as a capacitor. Specifically, when an alternating voltage is applied to the internal electrode 150, the dielectric film acts as a capacitor to generate a dielectric barrier discharge in the discharge space 120. The discharge efficiency of the dielectric barrier discharge is very closely related to the capacitance of the capacitor. Therefore, since the capacitance can be adjusted by adjusting the thickness of the dielectric film, the luminous efficiency of the surface light source device 100 can also be improved. The protective layer 152 has a thickness of about 0.005 to 0.3 mm.

On the other hand, a reflective layer (not shown) is formed on the surface of the first substrate 111. The reflective layer reflects the light directed toward the first substrate 111 among the light generated in the discharge space 120 toward the second substrate 112. A first fluorescent layer (not shown) is formed on the surface of the reflective layer, and a second fluorescent layer (not shown) is formed on the bottom surface of the second substrate 112. The first and second fluorescent layers serve to convert the ultraviolet rays generated in the discharge space 120 into visible light.

According to the present embodiment, since the voltage is directly applied from the internal electrode to the discharge gas, the luminous efficiency may be improved by about 10% compared to the surface light source device having the external electrode.

Example 2

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

Referring to FIG. 7, the backlight unit 1000 according to the present embodiment includes the surface light source device 100, the upper and lower cases 1100 and 1200, the optical sheet 900, and the inverter 1300 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.

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 to accommodate the surface light source device 300. The surface light source device 100 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 100. The discharge voltage generated from the inverter 1300 is applied to the internal electrodes 150 of the surface light source device 100 through the first and second power lines 1352 and 1354, respectively.

The optical sheet 900 may include a diffuser 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 1100 is coupled to the lower case 1200 to support the surface light source device 100 and the optical sheet 900. The upper case 1100 prevents the surface light source device 100 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.

According to the present invention as described above, since the electrode is disposed inside the light source body, a voltage is directly applied to the discharge gas. Therefore, the luminous efficiency 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 (7)

A light source body having partition walls having a width of 3 to 5 mm to define a plurality of discharge spaces into which discharge gas is injected; And And an internal electrode disposed inside the light source body and having protrusions for applying a voltage to the discharge gas. The light source body of claim 1, wherein the light source body includes first and second substrates disposed opposite to each other, and the internal electrode is provided on the first substrate, the second substrate, or the first and second substrates. Surface light source device. The surface light source device of claim 1, wherein the internal electrode is made of nickel, copper, or silver. The surface light source device of claim 1, wherein the internal electrode has a thickness of 0.005 to 0.5 mm. The surface light source device of claim 1, further comprising a protective layer formed of a dielectric material formed on an outer surface of the inner electrode. The surface light source device of claim 1, wherein the protrusion has a rectangular cross section, a triangular cross section, or a semicircular cross section. A light source body having partition portions having a width of 3 to 5 mm defining a plurality of discharge spaces into which discharge gas is injected, and an interior disposed inside the light source body for applying voltage to the discharge gas and having protrusions A surface light source device including an electrode; 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 configured to apply a discharge voltage for driving the surface light source device to the internal electrode.

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