KR20080036379A - Flat light source device and display device having the same - Google Patents

Abstract

A surface light source device and a backlight unit having the same are provided to increase a discharge current and spread electric discharge generated between electrodes to both ends of the surface light source device by using extension electrodes and a substrate of which the upper surface is inclined such that the thickness of both ends with the electrodes is thin and the thickness of the center part is thick, thereby improving brightness, brightness uniformity, and optical efficiency. A surface light source device comprises a first substrate(101), a second substrate(102), a partition(104), and electrodes(121,122). The second substrate is joined to the first substrate to form a discharge area. The partition divides the discharge area into plural discharge units. The electrodes are respectively installed to both ends of the discharge unit to apply a discharge voltage to the discharge area. The center area of at least one of the first and second substrates is thicker than the other area of the substrate.

Description

Surface light source device and backlight unit having the same {FLAT LIGHT SOURCE DEVICE AND DISPLAY DEVICE HAVING THE SAME}

1 and 2 are perspective views showing the shape of a conventional flat fluorescent lamp.

Figure 3a is a perspective view of a surface light source device according to an embodiment of the present invention.

3B is a cross-sectional view of the surface light source device of FIG. 3A taken along line II ′.

4 is a cross-sectional view showing a conventional surface light source device.

5A is an exploded perspective view illustrating a backlight unit according to another embodiment of the present invention.

FIG. 5B is a cross-sectional view taken along line II of FIG. 5A.

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

100 flat plate fluorescent lamp 101 first substrate

102 second substrate 103 partition wall

121: first electrode 122: second electrode

131: light reflection layer 141: fluorescent film

201: Optical sheet 301: Mold

302: lower storage container 401: inverter

402: power supply line

The present invention relates to a surface light source device and a backlight unit having the same, and more particularly, to a flat panel fluorescent lamp for generating light in the form of a surface and a backlight unit for a liquid crystal display device having the same.

Recently, the liquid crystal display device, which has been in the spotlight, is a flat panel display device, and has been easily used in various fields including a mobile phone, a monitor, a TV, and the like.

Since the liquid crystal display is a light-receiving device that displays an image by adjusting the amount of light that enters the liquid crystal display panel from the outside, a backlight assembly, which is a separate light source for irradiating light to the liquid crystal display panel, is required.

Cold cathode fluorescent lamps (CCFL) have been mainly used as the light source of the backlight assembly. However, as the size of liquid crystal displays increases, the number of cold cathode fluorescent lamps required increases, resulting in increased manufacturing costs and inferior optical characteristics such as luminance uniformity.

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

1 and 2 are perspective views showing the shape of a conventional flat fluorescent lamp. 1 is a perspective view of a flat fluorescent lamp of which the inner partition is separated, and FIG. 2 is a perspective view of an integrated flat fluorescent lamp. The electrodes are positioned at both ends of the internal space divided into a plurality of discharge spaces, and contact with the plasma is blocked by the substrate constituting the body of the lamp. Therefore, the driving voltage of the flat fluorescent lamp is considerably larger than that of the cold cathode fluorescent lamp in which the electrode is exposed to the plasma. As the size of the flat fluorescent lamp increases, the distance between the electrodes increases, so that the driving voltage becomes too large. .

Since the planar fluorescent lamp is limited in current by the capacitance of the substrate constituting the body, the amount of discharge current is smaller than that of the cold cathode fluorescent lamp. Since the brightness of the lamp is proportional to the amount of discharge current, there is a problem that the capacitance of the flat fluorescent lamp substrate acts as a limiting factor of the brightness of the lamp.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a surface light source device having improved brightness and brightness uniformity, light efficiency and a backlight unit including the same.

The object is that according to the present invention, in the surface light source device, the surface light source device divides the first substrate, the second substrate to form a discharge region in combination with the first substrate, and the discharge region into a plurality of discharge units. It can be achieved by a surface light source device which is provided at both ends of the partition wall and the discharge unit and includes an electrode for applying a discharge voltage to the discharge region.

In this case, it is preferable that the central region of at least one of the first substrate and the second substrate is thicker than other regions of the substrate.

The electrode includes a first electrode formed on an outer surface of the first substrate and a second electrode formed on an outer surface of the second substrate, and the first electrode extends further to a center portion of the discharge region than the second electrode. It is preferably formed.

In addition, the cross section of the first substrate cut in the longitudinal direction of the discharge unit preferably has a constant inclination toward the center portion.

In this case, the upper surface of the first substrate may have a constant curvature.

The electrode may be attached to the outer surfaces of the first substrate and the second substrate in the form of a conductive substrate or a tape, or may be formed by coating conductive powder on the outer surfaces of the first substrate and the second substrate.

In this case, the electrode preferably includes at least one material of aluminum (Al), chromium (Cr), silver (Ag), gold (Au), nickel (Ni) or copper (Cu).

In addition, the first substrate and the second substrate preferably comprises a glass material.

The reflective film may be formed on an inner surface or an outer surface of the first substrate, and the reflective film may be formed of a metal oxide material.

In this case, it is preferable to form a fluorescent film on the inner surface of the second substrate or the inner surface of the first substrate and the second substrate, and to inject a discharge gas into the discharge region, the partition wall is a communication path for communicating the discharge unit. It may be provided.

An object of the present invention is a first substrate, a second substrate coupled to the first substrate to form a plurality of discharge spaces, first electrodes formed on both ends of the lower surface of the first substrate and exposed to the outside, the first substrate 2 may be achieved by a backlight unit including a second electrode formed at both ends of the upper surface of the substrate and exposed to the outside and an inverter applying a discharge voltage to the electrode.

In this case, it is preferable that the distance between the end of the first substrate and the end of the second substrate is greater than the distance between the center of the first substrate and the center of the second substrate.

In addition, the first electrode preferably has a larger width than the second electrode.

In this case, the first electrode and the second electrode may be formed on the outer surface of the first substrate and the second substrate in the form of a conductive substrate or a tape, or by coating a conductive powder on the outer surface of the first substrate and the second substrate. .

In addition, the cross section of the first substrate cut in the longitudinal direction of the discharge space preferably has a constant inclination toward the center portion.

In this case, the upper surface of the first substrate may have a constant curvature.

The first substrate may have a rectangular shape, and the upper portion of the cross section of the first substrate cut in the longitudinal direction may be substantially an isosceles triangle or trapezoidal shape.

In addition, it is preferable that the inner surface or the outer surface of the first substrate further comprises a reflective film of a metal oxide material.

At this time, it is preferable to form a fluorescent film on the inner surface of the second substrate or the inner surface of the first substrate and the second substrate and inject a discharge gas into the discharge space.

The backlight unit may include an inverter for applying a discharge voltage to the first electrode and the second electrode, and an optical sheet interposed on the second substrate.

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

3A is a perspective view of a surface light source device according to an embodiment of the present invention, and FIG. 3B is a cross-sectional view of the surface light source device of FIG. 3A taken along line II ′.

3A to 3B, a surface light source device according to an embodiment of the present invention includes a first substrate 101, a second substrate 102, a partition 103, and electrodes 121 and 122. The first substrate 101 has a rectangular shape, and the two corner portions at which the electrodes are formed are thinner than the center portion, so that the upper portion of the first substrate 101 has an inclined surface in a section cut along the line II ′. D in FIG. 3B is a step between the thickest part and the thinnest part of the upper surface of the first substrate 101. The second substrate 102 is positioned above the first substrate 101 and a plurality of partitions 103 are disposed at regular intervals between the two substrates to constitute a plurality of discharge units. The discharge gas is injected into the discharge unit. Mercury gas, argon gas, neon gas, xenon gas, or krypton gas may be used as the discharge gas. The first substrate 101 and the second substrate 102 may be made of a light-transmissive material such as glass. Edges of the first substrate 101 and the second substrate 102 are sealed by the sealing member 104 to form an inner space. The first electrode 121 is disposed so that the longitudinal direction of the first electrode 121 and the longitudinal direction of the partition 103 are substantially orthogonal to two corner portions of the lower portion of the first substrate 101. The second electrode 122 is disposed at two corners of the upper portion of the second substrate 102 such that the length direction of the second electrode 122 and the length direction of the first electrode 121 are parallel to each other. In this case, the first electrode 121 extends to the center portion of the first substrate 101 to have a width larger than that of the second electrode 122.

As the first electrode 121 and the second electrode 122, a conductive material having a light reflection function such as aluminum (Al) may be used. In addition, chromium (Cr), silver (Ag), gold (Au), nickel (Ni), copper (Cu), or the like may be used. The method of attaching the electrode to the substrate is a method of attaching an electrode in the form of a substrate comprising at least one component of the conductive material to the first substrate 101 and the second substrate 102, and manufacturing the electrode in the form of a conductive tape. And a method of coating the conductive powder or paste on the outer surface of the substrate to form the same.

The light reflection layer may be formed on the inner surface or the outer surface of the first substrate 101. The light reflection layer serves to reflect visible light traveling downward of the first substrate 101. As the component constituting the light reflection layer, a metal oxide capable of increasing the reflectance and reducing the change in color coordinates may be used. For example, a material including aluminum oxide (Al 2 O 3) or barium sulfate (BaSO 4) may be used.

The first substrate 101 and the second substrate 102 further include a fluorescent film formed on the inner surface, that is, the region of each substrate corresponding to the discharge regions of the upper portion of the first substrate 101 and the lower portion of the second substrate 102. The fluorescent film is excited by ultraviolet rays generated through plasma discharge in the discharge region to emit visible light. When the light reflection layer is formed on the inner surface of the first substrate 101, the fluorescent film is formed on the light reflection layer. The fluorescent layer can also be formed on the inner surface and the partition 103 of the substrate.

4 is a cross-sectional view showing a conventional surface light source device. The first electrode 121 of FIG. 3B, which is a cross-sectional view of a surface light source device according to an embodiment of the present invention, has a wider width than the conventional electrode. By using such an extended electrode structure, the electrode spacing is greatly reduced, so that the driving voltage of the lamp can be greatly reduced regardless of the size of the surface light source device, and the area of the electrode is enlarged to reduce the size of the capacitance by the substrate. The discharge current is increased. Since the discharge current and luminance are proportional and the discharge current amount is large, the luminance stabilization time decreases, so that the present structure increases the luminance and decreases the luminance stabilization time. The important point in applying such an extended electrode is that the discharge generated between the electrodes must be stably spread to both ends of the surface light source device. Instead of using a glass plate of uniform thickness as the first substrate, as shown in FIG. 3B, when a substrate having an inclined top surface is applied so that the center portion is thickest and the thickness becomes thinner toward the edge, the substrate becomes closer to the edge of the substrate. The magnitude of the electric capacity (Capacitance) is gradually increased to increase the amount of discharge current that can flow. The change in capacitance according to the position of the substrate serves to propel the plasma diffusion so that the discharge generated at the lower electrode, that is, the first electrode 121, can be stably spread to both ends of the lamp.

In the surface light source device using the extended type electrode, the positive column formed between the electrodes at the beginning of discharge has a relatively low light efficiency because of its short length. However, as the discharge formed over time spreads to the edges of the discharge zone, the length of the beam is increased, so that the light efficiency gradually increases. As shown in FIG. 3B, when a substrate having an inclined top surface is applied, discharge is present in a region of a substrate having a small capacitance in the early stage of discharge in which light efficiency is relatively low, and power consumption is reduced, and the discharge spreads to both ends of the discharge region. In this case, the discharge having a relatively high light efficiency is present in the region of the substrate having a large capacitance, that is, in the thickness. That is, in the surface light source device to which the extended electrode is applied, the surface light source device to which the inclined substrate is applied shows higher efficiency than the surface light source device to which the flat substrate having no inclined surface is applied.

Even if the bottom surface of the upper substrate is inclined to have a thick central portion, the capacitance can be changed according to the position of the substrate. Therefore, the surface light source device using the extended electrode and having a thick central portion of the upper substrate can be used. It is also possible to obtain the effect of the present invention through the surface light source device to which the central portion is applied thick structure.

FIG. 5A is an exploded perspective view illustrating a backlight unit according to another exemplary embodiment of the present invention, and FIG. 5B is a cross-sectional view taken along line II of FIG. 5A.

5A to 5B, a surface light source device according to another embodiment of the present invention may include a first substrate 101, a second substrate 102, a first electrode 121, and a second electrode 122. It includes a flat plate fluorescent lamp 100, an inverter 600, a power line 402, optical sheets 201 and a containing container. The first substrate 101 has a thin thickness at the two corners at which the electrodes are formed, and the thickness of the central portion is thick, so that the upper portion of the first substrate 101 may have a plurality of inclined surfaces or inclined curved surfaces. As shown in FIG. 5B, the upper surface of the first substrate has an isosceles triangle shape in cross section taken along line I-I of FIG. 5A. At this time, both ends of the upper surface may have a thin trapezoidal shape or a curved shape with a thick thickness at the center portion.

 The second substrate 102 is positioned above the first substrate 101 and is coupled to the first substrate 101 to form a plurality of discharge spaces. Discharge gas is injected into the discharge space. An edge of the second substrate 102 that is coupled to the first substrate 101 may be sealed using a sealing member. In this case, an area of the second substrate 102 that is coupled to the first substrate 101 may be formed to be in close contact with the upper surface of the first substrate 101 by forming an inclined surface or an inclined curved surface.

In the shape of the first substrate 101 and the second substrate 102, in addition to the above-described shapes, the substrate is formed in a separate region that is combined with the second substrate 102 on the upper surface of the first substrate 101 to form a discharge space. The shape in which the pattern corresponding to the discharge space is formed on the upper surface of the first substrate 101 may be applied so that the thickness of the region corresponding to the edge portion of the substrate is thin and the thickness of the region corresponding to the center portion of the substrate is thick. have.

As illustrated, the first electrode 121 is disposed at two lower corners of the first substrate 101, and the second electrode 122 is disposed at the upper two corners of the second substrate 102. 121). The pattern forming the discharge space of the second substrate 102 may be manufactured in various forms such as a semi-circle, semi-ellipse, or triangular prism according to the characteristics of the product to be manufactured and the ease of fabrication. The second electrode 122 formed at two upper corners of the second electrode 122 may be formed to correspond to the pattern of the second substrate 102. The length direction of the first electrode 121 and the length direction of the second electrode 122 are substantially parallel, but the first electrode 121 has a larger width than that of the second electrode 122. Extends to the center of 101).

Aluminum (Al), chromium (Cr), silver (Ag), gold (Au), nickel (Ni), copper (Cu), or the like may be used as a material forming the first electrode 121 and the second electrode 122. Can be. The method of attaching the electrode to the substrate may include fabricating an electrode in the form of a substrate and attaching the electrode to the substrate, or fabricating and attaching the electrode in the form of a conductive tape, or coating and forming a conductive powder or paste on an outer surface of the substrate. Can be used.

The light reflection layer 131 may be formed on the inner surface or the outer surface of the first substrate 101. The light reflection layer 131 reflects the visible light traveling downward of the first substrate 101. The light reflection layer 131 may be formed using a material including a metal oxide.

A fluorescent film 141 is formed on the lower surface of the second substrate 102 corresponding to the discharge space, and the fluorescent film 141 is excited by ultraviolet rays generated through plasma discharge in the discharge space to emit visible light. . The fluorescent film 141 may be formed on a lower surface corresponding to the discharge space of the second substrate 102 and an upper surface corresponding to the discharge space of the first substrate 101.

The inverter 401 generates a discharge voltage for driving the flat fluorescent lamp 100. The inverter 401 boosts and outputs an AC voltage applied from the outside to a discharge voltage of high potential. The discharge voltage output from the inverter 401 is applied to the first electrode 121 and the second electrode 122 through the power supply line 402.

The optical sheet 201 may include a light collecting sheet for improving front brightness and a diffusion sheet for diffusing light, and improve brightness and brightness uniformity of light emitted from the flat fluorescent lamp 100. In this case, an optical plate may be further provided between the planar fluorescent lamp 100 and the optical sheets 201 to improve luminance characteristics.

The lower housing 302 includes a flat fluorescent lamp 100 which is formed of a bottom portion and a side portion extending from an edge of the bottom portion to provide an accommodation space.

The mold 301 is disposed between the optical sheets 201 and the liquid crystal display panel to fix the optical sheets 201 and the flat panel fluorescent lamp and to support the liquid crystal display panel. A second mold may be additionally disposed between the optical sheets 201 and the flat fluorescent lamp 100 to fix the flat fluorescent lamp 100 and to support the optical sheets 201.

As described above, the surface light source device according to the present invention uses a substrate having an inclined upper surface such that the extended electrode and the both ends of the electrode are thin and the thickness of the central part is thick, thereby increasing the discharge current and the discharge generated between the electrodes. It is possible to stably spread to both ends of the light source device, thereby improving brightness, brightness uniformity and light efficiency.

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 knowledge in the scope of the invention described in the claims to be described later And it will be understood that various modifications and changes of the present invention can be made without departing from the scope of the art.

Claims (20)

A first substrate; A second substrate coupled to the first substrate to form a discharge region; A partition wall dividing the discharge area into a plurality of discharge units; And In the surface light source device is provided at both ends of the discharge unit, and including an electrode for applying a discharge voltage to the discharge area, And a central area of at least one of the first and second substrates is thicker than another area of the substrate. The method of claim 1, The electrode includes a first electrode formed on an outer surface of the first substrate and a second electrode formed on an outer surface of the second substrate, wherein the first electrode extends further to the center portion of the discharge region than the second electrode. Surface light source device, characterized in that. The method of claim 1, And a cross section of the first substrate cut in the longitudinal direction of the discharge unit has a constant inclination toward the center portion. The method of claim 1, The upper surface of the first substrate has a constant curvature, characterized in that the surface light source device. The method of claim 2, The first electrode and the second electrode is a surface light source device, characterized in that attached to the outer surface of the first substrate and the second substrate in the form of a conductive substrate or a tape. The method of claim 2, The first electrode and the second electrode is a surface light source device, characterized in that formed by coating a conductive powder or paste on the outer surface of the first substrate and the second substrate. The method of claim 2, The first electrode and the second electrode comprises at least one material of aluminum (Al), chromium (Cr), silver (Ag), gold (Au), nickel (Ni) or copper (Cu). Surface light source device. The method of claim 1, The first substrate and the second substrate is a surface light source device characterized in that it comprises a glass material. The method of claim 1, The surface light source device of claim 1, further comprising a metal oxide reflective film formed on an inner surface or an outer surface of the first substrate. The method of claim 1, And a fluorescent film formed on an inner surface of the second substrate or on inner surfaces of the first and second substrates, and a discharge gas injected into the discharge region. The method of claim 1, The partition wall surface light source device characterized in that it comprises a communication path for communicating the discharge unit. A first substrate; A second substrate coupled to the first substrate to form a plurality of discharge spaces; First electrodes formed at both ends of the lower surface of the first substrate and exposed to the outside; Second electrodes formed on both ends of an upper surface of the second substrate and exposed to the outside; And In the backlight unit comprising an inverter for applying a discharge voltage to the electrode, And a distance between an end portion of the first substrate and an end portion of the second substrate is greater than a distance between the center portion of the first substrate and the center portion of the second substrate. The method of claim 12, The first electrode has a greater width than the second electrode. The method of claim 12, The cross-section of the first substrate cut in the longitudinal direction of the discharge space has a constant inclination toward the center portion. The method of claim 12, The upper surface of the first substrate has a constant curvature, characterized in that the backlight unit. The method of claim 12, The first electrode and the second electrode is a backlight unit, characterized in that attached to the outer surface of the first substrate and the second substrate in the form of a conductive substrate or a tape. The method of claim 12, The first electrode and the second electrode is formed by coating a conductive powder or paste on the outer surface of the first substrate and the second substrate. The method of claim 12, And a metal oxide reflective film formed on an inner surface or an outer surface of the first substrate. The method of claim 12, And a fluorescent film formed on an inner surface of the second substrate or on inner surfaces of the first and second substrates, and a discharge gas injected into the discharge space. The method of claim 12, And an inverter for applying a discharge voltage to the first electrode and the second electrode, and an optical sheet interposed on the second substrate.

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