This application claims the benefit of Korean Patent Application No. ______, filed on ______, which is hereby incorporated by reference as if fully set forth herein.
1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to a dielectric of a plasma display panel and a method for manufacturing the same.
2. Discussion of the Related Art
With the advent of a multimedia age, there has been a demand for displays that exhibit a higher-definition, have a larger-screen and are capable of realizing excellent natural color reproduction. Since cathode ray tubes (CRTs) have a limitation in realizing a large screen (i.e., 40 inch or more), displays such as liquid crystal displays (LCDs), plasma display panels (PDPs) and projection televisions (TVs) are rapidly progressed to extend applications thereof to the high-definition image field.
When compared to self-luminous CRTs, the fore-mentioned displays including PDPs have essential characteristics in that they can be manufactured to a small thickness, and a large screen (i.e., 60 to 80 inch) is readily manufactured. In addition, the displays are significantly different from self-luminous CRTs, in views of styles and designs.
PDPs include a lower substrate including an address electrode, an upper substrate including a pair of sustain electrodes, discharge cells defined by barrier ribs and a phosphor applied at each discharge cell so as to display an image. Specifically, when discharging occurs in a discharge zone between the upper and lower substrates, ultraviolet rays are generated and transmitted to the phosphor to emit visible rays, thereby displaying an image.
However, the fore-mentioned plasma display panels and a method for manufacturing the same have several problems as follows.
In order to improve luminescent efficiency of PDPs, it is necessary to reduce discharge current thereof. However, the discharge current is greatly affected by the thickness of the dielectric layer. Generally, when a dielectric layer has a small thickness, discharge firing voltage is decreased and discharge current is increased, and when the dielectric layer has a large thickness, the discharge firing voltage is increased and discharge current is decreased. Accordingly, when the thickness of the dielectric layer is simply increased, the discharge current is decreased, but the discharge firing voltage is increased.
Other problems of the conventional PDPs are as follows:
A contrast ratio of PDPs refers to a ratio of a maximum brightness and a minimum brightness. Since PDPs have a light reflection ratio at a bright room, they have a lower bright room contrast ratio than those of other displays such as LCDs. In addition, PDPs exhibit high external-light reflection ratios, thus causing a deterioration in color temperature.
Accordingly, the present invention is directed to a plasma display panel and a method for manufacturing the same that substantially obviate one or more problems due to limitations and disadvantages of the related art.
One object of the present invention is to provide a method for forming a differential dielectric on a substrate of a plasma display panel and an apparatus used in the formation of the dielectric.
Another object of the present invention is to provide a plasma display panel with an increased bright room contrast ratio and an improved color temperature.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a method for manufacturing a plasma display panel comprises: preparing a first substrate including an address electrode, a dielectric and a barrier rib; applying a first dielectric to a second substrate including a pair of sustain electrodes; applying a plurality of second dielectrics to the first dielectric with a dispensing system having a nozzle equipped with a plurality of reverse-trapezoid injection ports, such that the second dielectrics have a differential structure; drying the first and second dielectrics, followed by baking; forming a protective film on the first and second dielectrics; and joining the first substrate to the second substrate.
In another aspect of the present invention, a plasma display panel comprises: a first substrate and a second substrate joined to each other, such that a barrier rib is interposed between the first and second substrates; an address electrode and a dielectric arranged in this order on the first substrate; a pair of sustain electrodes and a first dielectric arranged in this order on the second substrate; a plurality of second dielectrics arranged on the first dielectric, each second dielectric exhibiting a chromatic color, gray or black, and having topology; and a protective film arranged on the first and second dielectrics.
In yet another aspect of the present invention, a method for manufacturing a plasma display panel comprises: preparing a first substrate including an address electrode, a dielectric and a barrier rib; applying a first dielectric to a second substrate including a pair of sustain electrodes; applying a second dielectric composed of a chromatic, gray or black material to a region corresponding to a non-discharge zone of the first dielectric with a dispensing system; drying the first and second dielectrics, followed by baking; forming a protective film on the first and second dielectrics; and joining the first substrate to the second substrate.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:
Other aspects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
Like numbers refer to like elements throughout the description of the figures. In the drawings, the thickness of layers and regions are exaggerated for clarity and the thickness ratio between the layers may not necessarily express an actual value.
As shown in
In addition, the PDP includes dielectrics and a protective film 195 arranged on the upper substrate 170 such that they cover the sustain electrodes and the bus electrodes. The upper substrate 170 is formed by processing (including milling, cleaning and the like) a glass for displays. The sustain electrodes 180a and 180b are formed by photoetching method through sputtering of a material such as indium-tin-oxide (ITO) or SnO2, or a lift-off method through chemical vapor deposition (CVD) of the material. The bus electrodes 180a′ and 180b are composed of a material such as silver (Ag). In addition, scan electrodes and the sustain electrodes include a black matrix consisting of a low melting point glass and a black pigment.
Dielectrics are arranged over the upper substrate 170 where the sustain electrodes 180a and 180b, and the bus electrodes 180a′ and 180b′ are formed. As shown in
The second dielectrics 190b include a metal oxide, in addition to a transparent low-melting point glass. The metal oxide includes at least one selected from cobalt oxide, copper oxide, manganese oxide and chrome oxide. Accordingly, the second dielectrics 190b have a chromatic color, gray or black.
The second dielectrics 190b are formed in a region only corresponding to a non-discharge zone of the first dielectric 190a. That is to say, no second dielectric 190b is formed in a region corresponding to the space between the sustain electrode pairs 180a and 180b. Accordingly, the second dielectrics have a non-uniform thickness and have a differential structure. As shown in
The second dielectrics 190b have a thickness of about 7.5 to 33 micrometers and are arranged to be spaced apart from each other by a distance of 200 to 400 micrometers. The second dielectrics 190b have a width of 276 to 476 micrometers.
The protective film 195 is arranged on the first dielectric 190a and the second dielectrics 190b. The protective film 195 includes magnesium oxide, and the like. Upon discharging, the protective film 195 protects the dielectrics against impacts of anions and increases secondary electron emission. The protective film 195 may have a bilayer structure. A first layer being in contact with the dielectric is composed of a thin film and a second layer being in contact with the discharge region is composed of a magnesium oxide single crystal in the form of a nanopowder, and may thus have an uneven surface. Upon gas discharging, the surface area of ultraviolet ray ions which collide with the protective film is increased and the number of electrons participating in secondary emission is thus increased and a discharge firing voltage is reduced. As a result, discharge efficiency can be improved and a jitter can be reduced.
A plurality of address electrodes 120 are arranged on one side of the lower substrate 110 such that each of them crosses the associated sustain electrode pairs 180a and 180b. A white dielectric 130 is arranged over the entire surface of the lower electrode 110 while covering the address electrodes 120. The white dielectric 130 is formed by applying a dielectric material onto the lower substrate 110 through printing or film laminating and baking the material. A barrier rib 140 is arranged on the white dielectric 130 such that it is interposed between the adjacent two address electrodes 120. The barrier rib 140 may be a stripe-, well-, or delta-type.
Although not shown, a black top 145 may be arranged on the barrier rib 140. One of Red (R), green (G) and blue (B) phosphor layers 150a, 150b and 150c is interposed between the adjacent barrier ribs 140. A plurality of discharge cells are each defined by an intersection between an associated one of the address electrodes 120 arranged on the lower substrate 110 and an associated one of the sustain electrode pairs 180a and 180b on the upper substrate 170.
The PDP according to one embodiment of the present invention can exhibit a reduced discharge firing voltage and an increased consumption power owing to topology of the dielectric arranged on the upper substrate. In addition, the dielectrics arranged on the upper substrate are partially colored, thus reducing external light reflection, increasing a bright room contrast ratio and increasing a color temperature.
As shown in
The sustain electrode pairs 180a and 180b are formed by a photoetching method through sputtering of a material such as ITO (indium-tin-oxide) or SnO2, or a lift-off method through chemical vapor deposition (CVD) of the material. The bus electrodes 180a′ and 180b are formed by a screen-printing or photosensitive-paste method using a material such as silver (Ag). A black matrix is formed on the sustain electrode pairs 180a and 180b. The black matrix is formed by a screen-printing or photosensitive paste method using a low melting point glass and a black pigment.
As shown in
Subsequently, a second dielectric 190b is formed on the first dielectric 190a. As shown in
There are several methods, e.g., screen printing or sanding, to form the second dielectric 190b.
The screen printing method is a technique that prints a second dielectric material 190b′ several times in a region, where the second dielectric 190b is intended to be formed. The formation of the second dielectric 190b using screen printing is carried out by printing a paste-type material at a predetermined pattern. The screen printing involves a simple process and employs inexpensive equipment.
However, the screen printing has bad uniformity of thickness and width, thus causing a deterioration in precision of a high-definition pattern. Further, the screen printing method leaves mesh marks of a screen mask even after a baking process, thus lowering a surface roughness. Particularly, in a large-sized panel, the screen printing method deforms the screen mask, thus causing disagreement of patterns.
The formation of the second dielectric 190b having a differential structure using the sanding method is carried out by forming a dielectric material by a green sheet technique, patterning a mask thereon, and cutting selectively a unnecessary portion using a kinetic energy of cutting particles, e.g., ceramic particles or ultra-fine particles of calcium carbonate, injected thereto at a high voltage. The sanding method enables formation of a layer to a width not more than 50 micrometers. However, the sanding method has problems of environmental contamination due to dust and cracks in a fine-definition pattern which results from the collision energy of the cutting particles.
Meanwhile, in the case where a coating or green sheet method is used to form the second dielectric 190b, a dielectric material is applied to the first dielectric 190a and then patterned. As shown in
As shown in
A more detailed explanation of the patterning process will be given below.
The mask 250 is positioned above the resulting structure, and irradiation is performed in a region only where the second dielectric 190b is intended to be formed. Preferably, the irradiation is selectively applied to the second dielectric material 190b′ present in a non-discharge zone. That is to say, in XGA grade PDPs, layers having a width of about 276 to 476 micrometers only are subjected to the irradiation. As a result, the second dielectric 190b is patterned to have topology and a thickness of 7.5 to 33 micrometers. In addition, although the shape of the second dielectric 190b shown in
The second dielectric 190b has a chromatic color, gray or black. When the metal oxide contained in the second electrode dielectric material 190b′ includes one selected from cobalt oxide, copper oxide, manganese oxide and chrome oxide, the final second dielectric 190b is blue in color.
Hereinafter, preferred embodiments of a method for forming the second dielectric using a dispensing system are illustrated.
A dielectric material stored in a dispenser 300 is applied through a nozzle to a substrate. The shape and thickness of the dielectric material applied to the substrate are varied according to a moving speed of the dispenser 300 and an amount of dielectric material discharged from the nozzle.
As mentioned above, after a differential dielectric structure is formed by applying the first dielectric 190a and the second dielectric material 190b′, the dielectric is subjected to drying and baking. The drying is a process to remove a solvent contained in the dielectric material and is preferably carried out at 100 to 150° C. Subsequently, the baking of the dielectric material is carried out at 500 to 600° C.
During the drying and baking, the flowable dielectric material undergoes partial deformation. That is, the reverse-trapezoid dielectric material 190b′ flows down at both edges of the top thereof, resulting in formation of a differential dielectric structure having a rectangle-like shape. That is, when the second dielectric material 190b′ is applied in a rectangular shape, the top thereof is partially collapsed during drying and baking, making the top curved or the overall structure a trapezoid. Accordingly, the dielectric material is applied such that it has a differential structure as a reverse-trapezoid form, and then subjected to drying and baking, to form a dielectric having a differential structure, i.e., a rectangle-like shape.
As mentioned above, a differential dielectric structure is formed by applying the first and second dielectric materials, and then subjected to drying and baking. Further details of such a process are the same as in the first embodiment.
During the drying and baking, the flowable dielectric material undergoes partial deformation. That is, the uppermost part of inks which are discharged from injection ports constituting each injection port group partially flows down and then joins the adjacent region. As a result, a differential dielectric structure having a rectangle-like shape is formed, as shown in
Accordingly, in the present embodiment, several differential dielectrics are applied to be adjacent to each other. During drying and baking, a portion of inks flow down and join together to form a rectangle shape. The injection port groups are designed such that they are spaced apart from each other by a long distance. For this reason, the second dielectric material composed of inks discharged from different injection port groups does not conglomerate, maintaining its overall differential structure.
Subsequently, as shown in
As shown in
As shown in
Subsequently, as shown in
The barrier rib material 140a is patterned to form barrier ribs. The patterning is carried out by exposing through a mask and developing. That is, the mask is located in a region corresponding to the address electrode, and the resulting structure is exposed to radiation, and then developed and baked. As a result, an exposed region only remains to form barrier ribs. When the barrier rib material contains a photoresist, it can be readily patterned.
Then, as shown in
As shown in
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
Number | Date | Country | Kind |
---|---|---|---|
10-2006-0126308 | Dec 2006 | KR | national |
10-2007-0031358 | Mar 2007 | KR | national |