KR20070118506A - Surface light source with flat reflective electorde and backlight unit having the same - Google Patents

Abstract

An FFL(Flat Fluorescent Lamp) with a combined reflective layer and flat electrode and a backlight unit having the same are provided to simplifying the manufacturing process of the FFL and secure economical efficiency of production by having no necessity for forming a separate reflective layer within a substrate by having the flat reflective electrode in the rear of the substrate not emitting light. An FFL includes a first substrate(210), a second substrate(220), a sealing member, and first and second surface electrodes(230,250). The second substrate is opposite to the first substrate at predetermined intervals. The sealing member is formed in the edge between the first and second surface substrates to seal the inner space formed by the first and second surface substrates. The first and second surface electrodes are separately formed in the whole surface of the first and second surface substrates. The first and second surface electrodes include a reflective electrode.

Description

FIELD OF THE INVENTION A surface light source device including a flat plate-type electrode with a reflective film and a backlight unit having the same {Surface Light Source With Flat Reflective Light And Backlight Units}

1 is a perspective view showing an example of a surface light source device.

2 is a perspective view showing a surface light source device according to the present invention.

Figure 3 is a side view showing a surface light source device according to the present invention.

4 is a sectional view taken along the line X-X 'of FIG.

5 is an enlarged view of a portion A of FIG. 4;

Figure 6 is a cross-sectional view showing an electrode portion of a multi-layer structure according to the present invention.

7 and 8 are plan views showing another example of the electrode pattern of the electrode unit according to the present invention.

9 is a sectional view showing a surface light source device including a reflection film.

10 is a cross-sectional view showing a surface light source device not including a reflective film.

11 is a perspective view showing a reflective plate-shaped electrode.

It is a schematic diagram which shows an example of the manufacturing process of a reflective flat plate electrode.

FIG. 13 is an enlarged view of a portion P of FIG. 12; FIG.

14 is a sectional view showing a surface light source device according to another embodiment of the present invention.

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

16 is an exploded perspective view showing a backlight unit including the surface light source device of the present invention.

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

200: surface light source device 210: first substrate

218: fluorescent layer 219: reflective film

220: second substrate 230: sealing member

235: spacer 240: discharge space

250: first surface electrode part 260: second surface electrode part

260 ': Reflective electrode

The present invention relates to an ultra-thin surface light source device and a backlight unit having the same, and in particular, to provide a new surface light source device suitable for a mercury-free lamp.

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 cathode ray tubes (CRTs). As a result, they are widely used in portable computers, communication devices, liquid crystal television receivers, and aerospace industries. .

The liquid crystal display device includes a liquid crystal controller for controlling liquid crystal and a rear light source for supplying light to the liquid crystal. The liquid crystal controller 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.

Light supplied from the rear light source 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 largely depends on the luminance and luminance uniformity of the rear light source. In general, the higher the luminance and the uniformity of the luminance, the better the display quality.

Conventionally, the rear light source of the liquid crystal display is mainly used a cold cathode fluorescent lamp (CCFL) having a rod shape or a light emitting diode (LED) having a dot shape. Cold cathode ray tube lamp has the advantage of high brightness, long life, and very low heat generation compared to incandescent lamps. On the other hand, the light emitting diode has a high power consumption, but has an advantage of excellent brightness. However, cold cathode ray tube type lamps or light emitting diodes have poor brightness uniformity. Accordingly, a rear light source having a cold cathode ray tube lamp or a light emitting diode as a light source is an optical member such as a light guide panel (LGP), a diffusion member, a prism sheet, or the like to increase luminance uniformity. (optical member) is required. 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.

As a back light source for a liquid crystal display, a flat fluorescent lamp (FFL) in the form of a flat plate has been proposed. Referring to FIG. 1, the conventional surface light source device 100 includes a light source body 110 and electrodes 160 provided on outer surfaces of both edges of the light source body 110. The light source body 110 includes first and second substrates disposed to face each other at predetermined intervals. A plurality of partitions 140 are disposed between the first and second substrates to partition the space between the first and second substrates into a plurality of discharge channels 120. A sealing member (not shown) is disposed between the edges of the first and second substrates to isolate the discharge channels 120 from the outside. Discharge gas is injected into the discharge space 150 inside the discharge channel.

In order to discharge-drive the surface light source device, an electrode is applied to the first substrate and the second substrate or one of the two substrates so that the electrodes have the same area per discharge channel in the form of a strip of strips or in the form of island electrodes. Therefore, when the surface light source device is driven using an inverter, all the front channels are discharged in the same manner.

The surface light source device has a problem in that luminance uniformity is not good because the light emission characteristics vary depending on the position of the discharge channel. In addition, there is a problem that a dark portion is generated by channeling due to interference between adjacent channels between a plurality of discharge channels.

In particular, the existing surface light source device contains mercury (Hg) as a discharge gas, which is not only environmentally problematic, but also increases the luminance stabilization time when driving at low temperatures, and the temperature variation of the surface light source itself due to the temperature sensitivity of mercury. As a result, there is a problem in that the luminance uniformity is lowered.

In addition, many problems remain to increase the size of the surface light source device.

Accordingly, it is an object of the present invention to provide a novel surface light source device suitable for large area.

Another object of the present invention is to provide a surface light source device and a backlight unit which are excellent in brightness and luminance uniformity and which are thin.

Still another object of the present invention is to provide a new surface light source device and a backlight unit which are excellent in mass productivity and excellent in manufacturing economy.

According to the present invention, a first substrate, a second substrate facing the first substrate at predetermined intervals, and an inner side formed at an edge between the first substrate and the second substrate are formed by the first substrate and the second substrate. And a sealing member sealing the space, and first and second surface electrode portions formed on the entire surfaces of the first and second substrates, respectively, wherein the first surface electrode portion or the second surface electrode portion includes a reflective electrode. Provided is a surface light source device.

The reflective electrode may be formed of a thin metal tape, or may be formed by depositing a metal thin film on the surface of the first substrate or the second substrate. The deposition of the metal thin film may use a well-known deposition method such as chemical vapor deposition and sputtering, and the metal thin film having a predetermined pattern may be formed by using a photosensitive film patterned for deposition of the metal thin film.

In the surface light source device according to the present invention, a plurality of spacers are formed between the first substrate and the second substrate or a plurality of protrusions are integrally formed on an inner surface of the first substrate or the second substrate to form an inverted space therein. do.

At least one of the first and second surface electrode parts may include a base layer, an electrode pattern formed on an upper surface of the base layer, and a protective layer formed on the electrode pattern. In this case, it is preferable that the base layer and the protective layer are transparent to visible light. The electrode part may include a mesh structure or a stripe-shaped electrode pattern. The material of the electrode unit may be selected from any one selected from copper, silver, gold, aluminum, nickel, chromium, ITO, a carbon-based conductive material, a conductive polymer, and a composite material thereof. Preferably, at least one of the first and second surface electrode portions has an opening ratio of 60% or more to expose the first substrate or the second substrate.

In the surface light source device according to the present invention, the first substrate, the second substrate and the sealing member form an internal discharge space having an open structure, and it is preferable that a discharge gas excluding mercury is injected into the discharge space. There is no particular restriction on the discharge gas.

A diffusion layer in which glass beads are dispersed in the resin layer may be integrally attached to the first substrate or the second substrate to improve luminance uniformity of the emitted light.

The present invention also provides a surface light source device including a first substrate and a second substrate forming a sealed discharge space, an electrode portion formed on an outer surface of the first substrate, and a reflective electrode formed on an outer surface of the second substrate; A case accommodating the surface light source device; And an inverter configured to apply a voltage to the electrode unit and the reflective electrode.

The surface light source device according to the present invention does not need to form a reflective film inside the substrate by providing a flat reflective electrode on a rear substrate which does not emit light among the substrates constituting the light source body. Therefore, the surface light source device manufacturing process can be simplified and manufacturing economic efficiency can be secured. In addition, the reflective electrode may contribute to ultra-thinning of the surface light source device, thereby further expanding the application range of the backlight unit having the same.

On the other hand, in the surface light source device and the backlight unit according to the present invention, since the discharge space is not partitioned by the partition wall, the luminance and luminance uniformity of the light emitted to the entire surface of the substrate are excellent. In addition, the enclosed space formed by the first substrate, the second substrate and the sealing member forms an internal discharge space having an open structure, and a gas excluding mercury may be used as the discharge gas injected into the discharge space. It can be applied to eco-friendly products.

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

2 is a perspective view showing the surface light source device 200 according to an embodiment of the present invention, Figure 3 is a side view.

The surface light source device 200 includes a planar first substrate 210 and a planar second substrate 220 having the same shape. The first substrate 210 and the second substrate 220 is preferably a transparent thin glass substrate, each thickness is not particularly limited, but the thickness of about 1mm, preferably less than 0.5mm is suitable.

A fluorescent layer may be coated on the inner surfaces of the first substrate 210 and the second substrate 220, and a reflective film may be further formed on one of the first substrate and the second substrate. The first substrate 210 and the second substrate 220 face each other at predetermined intervals, and a sealing member 230 such as a frit is inserted into an edge thereof to form a sealed space.

In the surface light source device according to the present invention, a large area flat plate electrode is formed on an outer surface of a light source body formed by a first substrate and a second substrate. FIG. 4 is a cross-sectional view taken along line X-X 'of FIG. 2, and FIG. 5 is an enlarged view of portion A of FIG. 4, and as illustrated, the outer surfaces of the first and second substrates 210 and 220 are respectively formed. The first surface electrode portion 250 and the second surface electrode portion 260 are formed. The first surface electrode part 250 and the second surface electrode part 260 are formed of a surface electrode having a flat plate shape substantially covering the entire substrate area.

At least one of the first surface electrode portion 250 and the second surface electrode portion 260 preferably has an open ratio of 60% or more to expose the substrate to increase the transmittance of light emitted by the discharge from the light source body. Do.

The first substrate 210 and the second substrate 220 are flat, and the interior defined by the first substrate, the second substrate, and the sealing member is divided by partition walls as in the conventional surface light source device. Instead of the discharge space, the discharge space 240 of one open structure is formed. The spacing between the first substrate and the second substrate is very small compared to the substrate area, and the internal space is formed in one open structure, so that the vacuum exhaust and discharge gas can be easily injected. In addition, it is suitable to form a surface light source device using a gas other than mercury, such as xenon, argon, neon, and other inert gas, as a discharge gas.

The vertical space of the discharge space 240 between the first substrate 210 and the second substrate 220 may be determined by the spacer 235. The number and spacing of the spacers 235 may be determined in a range that does not impair the luminance characteristics of the light emitted from the surface light source device.

Alternatively, the height of the discharge space 240 may be defined by protrusions (not shown) integrally formed on the inner surface of the first substrate or the second substrate.

In the surface light source device according to the present invention, the first surface electrode portion 250 and the second surface electrode portion 260 may use a transparent electrode (for example, ITO), or may use a predetermined pattern of electrodes. . FIG. 6 is a cross-sectional view of an electrode unit according to an exemplary embodiment of the present invention. As illustrated, the lower base layer 252, the electrode pattern 256 formed on the base layer, and the base layer and the electrode pattern are disposed on the electrode layer 256. The electrode part of the multilayered structure of the protective layer formed in this can be confirmed.

In the case of an electrode part including only an electrode pattern, bonding to a glass substrate may be difficult and durability may be degraded, whereas the electrode part of the multilayer structure may be easily bonded to a substrate and ensure durability of the electrode pattern, and various types of electrode patterns may be used. There is an advantage that can be formed.

7 and 8 illustrate an example of the electrode pattern of the plate-shaped electrode of the present invention, and each shows a pattern of a network structure or a stripe shape, and patterns of other shapes, for example, circles, ellipses, and polygons, are regularly Arranged in a pattern form is also acceptable.

In general, a light source for a backlight includes Al ₂ O ₃ , TiO ₂ , BaTiO _3, or a mixture thereof so that either the first substrate or the second substrate serves as an emission surface of light generated in the discharge space, and the other substrate does not have external loss of light. Reflective films such as these are used.

In the surface light source device according to the present invention, as shown in FIG. 9, the first substrate may be a light exit surface, and the second substrate may include a reflective film 219 on an inner surface of the light generated through the second substrate. Do not lose to the outside. However, there is also a certain amount of luminous flux lost to the outside through the reflective film. On the other hand, the process of forming the reflective film on the substrate is a factor that increases the cost in manufacturing the surface light source device, there is a difficulty in selecting a suitable reflective film material.

In one embodiment of the present invention provides a further advantage by forming a flat electrode on the back of the substrate to function as a reflective film. Referring to FIG. 10, phosphors 218 are coated on the inner surfaces of the first substrate 210 and the second substrate 220 forming the discharge space, and the reflective film is not included. The first surface electrode portion 250 is formed on the upper surface of the first substrate 210, and the plate type electrode 260 ′ different from the first surface electrode portion is formed on the lower surface of the second substrate 220. do. This flat type electrode 260 'is schematically illustrated in FIG. The planar electrode 260 ′ is formed to have an extremely low opening ratio while covering substantially the entire surface of the second substrate 220, so that light generated in the discharge space may block transmission.

In other respects, the present invention may be regarded as a structure in which a surface electrode portion is formed on the outer surface of the first substrate 210 and a reflective film is formed on the outer surface of the second substrate 220. That is, the surface light source can be configured without an internal reflection film by using the first surface electrode portion and the second surface electrode portion having a significantly lower aperture ratio than the first surface electrode portion. Accordingly, the surface light source according to the present invention may be referred to as a surface light source having one outer surface electrode and one outer reflective film. In this case, the outer reflecting film may be formed in a pattern form having a significantly lower aperture ratio than the opposite outer surface electrode. That is, the external reflecting film preferably has an aperture ratio at which the substrate is exposed to substantially zero.

It is preferable to use Al, Cu, Ag, other metals or alloy materials as the electrode material so that the flat electrode 260 'may also function as a reflective film.

In order to have conductivity and reflectivity, the flat electrode 260 'is preferably a thin tape or dense thin film having no leakage area, but has a regular pattern such as a mesh structure, stripe shape, circle, ellipse, polygon, etc. It can also be formed. For example, a thin metal tape such as thin Cu or Al can be attached to the back of the substrate. Alternatively, the reflective plate electrode 260 'may be formed using well known thin film processes.

FIG. 12 schematically illustrates a process of forming a combined electrode on a substrate 220 by a thin film formation method such as chemical vapor deposition (CVD) or sputtering. Although a dense film is usually formed through such a thin film process, a film having a pattern shape with a fine interval may be formed if necessary.

Referring to FIG. 13, in which the portion P of FIG. 12 is enlarged, a process of forming the patterned photoresist 262 first on the substrate 220 and then forming the plate type electrode 260 ′ through a thin film process is described. As shown. If the plate-shaped electrode 260 'is formed in a fine pitch pattern, it will be able to function as a reflective film since it corresponds to a substantially dense thin film.

The surface light source device according to the present invention does not need to separately form a reflective film by forming a reflective flat electrode on the back surface of the substrate on which light is not emitted, and can easily be combined with other additional processes to greatly increase the productivity.

FIG. 14 illustrates another embodiment of the present invention, in which a reflective plate type electrode 260 'is formed on the rear surface of the second substrate, and the diffusion layer 300 is integrated on the upper surface of the first substrate 210. Referring to FIG. This diffusion layer can be formed, for example in a mixed structure in which glass beads are dispersed in the resin layer. The diffusion layer may be formed on an upper surface of the first surface electrode part 250. The diffusion layer may improve the luminance uniformity of the surface light source device and at the same time function as a protective layer of the substrate or the electrode portion, thereby avoiding the use of the optical member included in the backlight unit, thereby contributing to thinning.

15 illustrates another embodiment of the present invention, and shows a structure in which the spacer 215 is integrally formed on the substrate 210. Since a plurality of protrusions 215 formed on one surface of the substrate 210 act as a spacer, a separate spacer forming process may be avoided, and in addition to the reflective flat electrode 260 ′ described above, it may contribute to mass production. .

16 is an exploded perspective view showing a backlight unit including the ultra-thin surface light source device according to the present invention. As shown, the backlight unit 1000 includes a surface light source 200, upper and lower cases 1100 and 1200, an optical sheet 900, and an inverter 1300. The lower case 1200 includes a bottom portion 1210 and a plurality of sidewall portions 1220 extending to form an accommodation space from an edge of the bottom portion 1210 to accommodate the surface light source 200. The surface light source 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 200. The discharge voltage generated from the inverter 1300 is applied to the electrode portion of the surface light source 200 through the first and second power lines 1352 and 1354, respectively. The optical sheet 900 may include a diffuser plate for uniformly diffusing the light emitted from the surface light source 200, a prism sheet for imparting linearity to the diffused light, and the like. The upper case 1100 is coupled to the lower case 1200 to support the surface light source 200 and the optical sheet 900. The upper case 1100 prevents the surface light source 200 from being separated from the lower case 1200.

Unlike the illustrated figure, the upper case 1100 and the lower case 1200 may be formed as one integrated case. On the other hand, the backlight unit according to the present invention may not include the optical sheet 900 because the brightness and luminance uniformity of the surface light source device is excellent.

Although described above with reference to preferred embodiments of the present invention, those skilled in the art or those skilled in the art without departing from the spirit and scope of the invention described in the claims to be described later Various modifications and variations can be made in the present invention without departing from the scope thereof.

According to the present invention, since the reflective plate-type electrode is provided on the rear substrate from which light is not emitted in the surface light source device, it is not necessary to form a reflective film inside the substrate. Therefore, the surface light source device manufacturing process can be simplified and manufacturing economic efficiency can be secured. In addition, the reflective plate-shaped electrode may contribute to ultra-thinning of the surface light source device and further expand the application range of the backlight unit having the same. In addition, according to the present invention, the inside of the surface light source device forms a discharge space of one open structure, it is possible to use a gas excluding mercury as the discharge gas injected into the discharge space can be applied to environmentally friendly products. In addition, since the discharge space is not partitioned by the partition wall, the luminance and luminance uniformity of the light emitted to the entire surface of the substrate are excellent.

Claims (17)

The first substrate, A second substrate facing the first substrate at predetermined intervals; A sealing member formed at an edge between the first substrate and the second substrate to seal an internal space formed by the first substrate and the second substrate; First and second surface electrode portions formed on the entire surface of the first substrate and the second substrate, respectively, Wherein the first surface electrode portion or the second surface electrode portion includes a reflective electrode. Surface light source device. The surface light source device of claim 1, wherein the reflective electrode is a thin metal tape. The surface light source device of claim 1, wherein the reflective electrode is a metal film deposited on a surface of a first substrate or a second substrate. The surface light source device of claim 1, wherein the reflective electrode is formed of any one material selected from Al, Cu, nickel, chromium, ITO, a carbon-based conductive material, a conductive polymer, or a combination thereof. The surface light source device of claim 1, wherein the reflective electrode further includes a pattern having a significantly lower aperture ratio than other opposing electrode portions. The surface light source device of claim 5, wherein the reflective electrode is formed of a pattern, a mesh pattern, or a stripe pattern in which circles, ellipses, polygons, and the like are regularly arranged. The semicircular surface light source device according to claim 1, wherein a plurality of spacers are formed between the first substrate and the second substrate. The surface light source device of claim 1, wherein a plurality of protrusions are integrally formed on an inner surface of the first substrate or the second substrate. The ultra-thin surface of claim 1, wherein at least one of the first and second surface electrode portions comprises a base layer, an electrode pattern formed on an upper surface of the base layer, and a protective layer formed on the electrode pattern. Light source device. 10. The surface light source device according to claim 9, wherein the base layer and the protective layer are transparent to visible light. The surface light source device of claim 9, wherein the electrode part comprises an electrode pattern having a regularly arranged pattern such as a circle, an ellipse, a polygon, a mesh pattern, or a stripe pattern. The method of claim 9, wherein the electrode unit is formed of any one material selected from copper, silver, gold, aluminum, ITO, nickel, chromium, carbon-based conductive materials, conductive polymers, and composite materials thereof. Surface light source device. The surface light source device according to claim 1, wherein at least one of the first and second surface electrode portions has an opening ratio of 60% or more to expose the first substrate or the second substrate. The surface light source device of claim 1, wherein the first substrate, the second substrate, and the sealing member form an internal discharge space having an open structure, and a discharge gas excluding mercury is injected into the discharge space. The surface light source device according to claim 1, wherein a diffusion layer in which glass beads are dispersed is integrally attached to the resin layer on the side of the first substrate or the second substrate. The first substrate, A second substrate facing the first substrate at predetermined intervals; A sealing member formed at an edge between the first substrate and the second substrate to seal an internal space formed by the first substrate and the second substrate; A surface electrode portion formed on an outer surface of the first substrate and having an opening ratio of at least 60% to expose the first substrate; And an external reflection film formed on an outer surface of the second substrate and not substantially exposing the second substrate. Surface light source device. A surface light source device including a first substrate and a second substrate forming a sealed discharge space, an electrode portion formed on an outer surface of the first substrate, and a reflective electrode formed on an outer surface of the second substrate; A case accommodating the surface light source device; And An inverter for applying a voltage to the electrode portion and the reflective electrode; Ultra-thin backlight unit.

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