Patent Application
20080238320
This application claims the benefit of Korean Application No. 2007-30365 filed Mar. 28, 2007, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference
1. Field of the Invention
Aspects of the present invention relate to a plasma display panel having an improved adhesion between a dielectric layer and a barrier rib, and a method of manufacturing the plasma display panel.
2. Description of the Related Art
Plasma display panels (PDP) generate vacuum (far) ultraviolet rays, from an inert gas, by applying a high-frequency voltage and irradiate fluorescent materials with the ultraviolet rays, to produce an image. PDPs are considered to be the next generation of large-scale, flat-panel display devices, due to excellent display properties, low weight, and thin structure.
PDPs include a dielectric layer and a barrier rib. The dielectric layer covers discharge electrodes, and the barrier rib is disposed close to the dielectric layer, to partition a plurality of discharge cells. In general, the dielectric layer and the barrier rib are formed of metal oxides. When the barrier rib is formed using a chemical etching method, the dielectric layer and the barrier rib should have different etching selectivities and thus, should have a different compositional ratios and/or constituents. More specifically, a barrier rib often includes metal oxides having a high etching selectivity, so that the barrier rib can be suitably etched by a predetermined etching solution, and the dielectric layer often includes metal oxides having a low etching selectivity. Therefore, due to the difference in properties between the barrier rib and the dielectric layer, the adhesion between the dielectric layer and the barrier rib may be reduced. Gas bubbles and/or voids may be generated during adhesion. In addition, the dielectric layer may be damaged and cell defects may occur, due to a reduction in the ability of the dielectric layer to withstand voltage.
Aspects of the present invention provide a plasma display panel having an improved adhesion between a barrier rib and a dielectric layer, so that the reliability of the plasma display panel is improved.
Aspects of the present invention also provide a method of manufacturing a plasma display panel having an improved adhesion between a barrier rib and a dielectric layer.
According to an aspect of the present invention, there is provided a plasma display panel (PDP) including: a substrate; a dielectric layer formed on the substrate; and a barrier rib disposed in contact with the dielectric layer. The dielectric layer or the barrier rib comprises a first material and a second material, with the relative concentrations of the first and second materials varying according to a gradient. The first material and the second material respectively have a low etching selectivity and a high etching selectivity. The etching selectivity relates to a predetermined etching solution.
The dielectric layer may include the first material as a major constituent The dielectric layer may include the first material in a concentration that gradually decreases in a direction toward the barrier rib. The dielectric layer may include the second material in a concentration that gradually increases in a direction toward the barrier rib.
The barrier rib may include the second material as a major constituent. Here, the barrier rib may include the second material in a concentration that gradually decreases in a direction toward the dielectric layer. The barrier rib may include the first material in a concentration that gradually increases in a direction toward the dielectric layer. The major constituent, as referred to herein, is the element present in the greatest amount in a compound.
The first material may include Bi2O3, PbO, or a combination thereof and have a low etching selectivity with respect to a nitric acid etching solution. The second material may include ZnO that has a high etching selectivity with respect to an etching solution.
Therefore, the dielectric layer and the barrier rib may include Bi2O3 or PbO, and ZnO, according to a concentration gradient. More specifically, the dielectric layer may include Bi2O3 or PbO in a concentration that gradually decreases in a direction toward the barrier rib, or ZnO in a concentration that gradually increases in a direction toward the barrier rib. In addition, the barrier rib may include Bi2O3 or PbO in a concentration that gradually increases in a direction toward the dielectric layer, or ZnO in a concentration that gradually decreases in a direction toward the dielectric layer.
According to another aspect of the present invention, there is provided a plasma display panel (PDP) including: a substrate; a dielectric layer formed on the substrate, including a first material having a low etching selectivity, with respect to a predetermined etching solution, as a major constituent; and a barrier rib disposed to contact the dielectric layer, including a second material, having a high etching selectivity, as a major constituent. The opposing surfaces of the dielectric layer and the barrier rib, an interface therebetween, can have roughened surfaces.
The first material can be Bi2O3 or PbO, materials that have a low etching selectivity with respect to a nitric acid etching solution. That is, the Bi2O3 and the PbO are not easily etched by the nitric acid etching solution. The second material can be ZnO, a material having a high etching selectivity with respect to the etching solution. The ZnO can be significantly dissolved by the etching solution.
According to another aspect of the present invention, there is provided a method of manufacturing a plasma display panel (POP) including: disposing a first paste layer, to form a dielectric layer, on a substrate; disposing a second paste layer, to form a barrier rib, on the first paste layer; drying the substrate; and plasticizing the substrate.
The drying may include performing a first drying process on the substrate and the first paste layer. After the first drying process is performed, the second paste layer may be disposed on the first paste layer. The drying may include performing a second drying process on the substrate including the second paste layer.
The first and second paste layers can be plasticized with a plasticizing agent. The plasticizing can occur after first and second layers are dried, or while the first and second paste layers are being dried. The drying and plasticizing process can be a single operation so that the PDP, according to aspects of the present invention, can be easily manufactured, and a poor adhesion between the dielectric layer and the barrier rib can be prevented.
Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.
The PDP 100 includes an upper panel 150 and a lower panel 160.
The upper panel 150 includes a plurality of sustain discharge electrodes 120 that extend in an X-direction on a first substrate 111, and an upper dielectric layer 113 covering the sustain discharge electrodes 120. A protective layer 115 is disposed on the upper dielectric layer 113,
The first substrate 111 may be formed of a soda-lime glass having an excellent light permeability. In addition, the first substrate 111 may be colored in order to reduce the reflection of external light and to improve bright-room contrast.
The sustain discharge electrodes 120 are formed parallel to each other and extend in the X-direction on the first substrate 111. The sustain discharge electrodes 120 include X electrodes and Y electrodes facing each other. The X and Y electrodes respectively include a bus electrode 121 and a transparent electrode 123.
The bus electrode 121 compensates for the relatively large resistance of the transparent electrode 123, so that a nearly uniform voltage can be applied to a plurality of discharge cells 190. The bus electrode 121 may be formed of chrome (Cr), copper (Cu), or aluminum (Al).
Voltage is applied to the transparent electrode 123, to generate a sustained discharge in the discharge cells 190. The transparent electrode 123 may be formed of a material having a high visible light transmissivity and a low electrical resistance, for example, indium tin oxide.
In the upper dielectric layer 113, a discharge current is restricted, so as to sustain a glow discharge. Due to a wall charge accumulation, memory function and voltage are reduced. In order to increase discharge efficiency and withstand voltage, the visible light transmissivity may be high.
The protective layer 115 protects the upper dielectric layer 113 and the sustain discharge electrodes 120, from charged particle collisions, and increases the emission coefficient of secondary electrons, so that the voltage required to initiate discharge is reduced. The protective layer 115 may be formed of magnesium oxide (MgO).
The lower panel 160 includes a plurality of address electrodes 173 that extend in a Y-direction on a second substrate 171, and a lower dielectric layer 175 covering the address electrodes 173. Barrier ribs 180, used to form a plurality of the discharge cells 190, having rectangular cross-sections, are disposed on the lower dielectric layer 175. Phosphor layers 177 are disposed inside the discharge cells 190.
The second substrate 171 may be formed of a soda-lime glass having an excellent light permeability. The second substrate 171 may be colored, in order to reduce reflection of external light, and to improve bright-room contrast.
The address electrodes 173 are disposed parallel to each other and extend in the Y-direction, on the second substrate 171. The address electrodes 173 may be formed of chrome (Cr), copper (Cu), or aluminum (Al). A substantially uniform voltage can be applied to the plurality of discharge cells 190, as in the bus electrode 121.
The lower dielectric layer 175 protects the address electrodes 173 from collisions with charged particles. In the lower dielectric layer 175, discharge current is restricted so as to sustain a glow discharge. Due to a wall charge accumulation, memory function and voltage are reduced.
The barrier ribs 180 are formed on the lower dielectric layer 175. A partition discharge space is formed between the first substrate 111 and the second substrate 171, thereby forming space for the plurality of discharge cells 190. The barrier ribs 180 may have a matrix-type structure. However, the present invention is not limited thereto, and the barrier ribs 180 may be also formed so that the cross-sections of the discharge cells 190 can have a variety of different shapes, such as, circular shapes and polygonal shapes.
The barrier ribs 180 are formed to contact the lower dielectric layer 175. When the barrier ribs 180 are formed, using a chemical etching method, the lower dielectric layer 175 is used as an etching stopping membrane. The lower dielectric layer 175 and the barrier ribs 180, respectively contain materials having different etching selectivities.
The lower dielectric layer 175 comprises a first material having a low etching selectivity, as a major constituent, that is not significantly etched by an etching solution. The barrier ribs 180 comprise a second material having a relatively high etching selectivity, as a major constituent, that is significantly etched by an etching solution. For example, the lower dielectric layer 175 may comprise Bi2O3 or PbO and can have a low etching selectivity with respect to a nitric acid etching solution, as a first material. The barrier ribs 180 may comprise ZnO as a second material and can have a high etching selectivity with respect to an etching solution.
The lower dielectric layer 175 and the barrier ribs 180, contain major constituents according to a concentration gradient. More specifically, the lower dielectric layer 175 comprises a first material in a concentration that gradually decreases in a direction toward the barrier ribs 180. The barrier ribs 180 can comprise a second material in a concentration that gradually decreases in a direction toward the lower dielectric layer 175.
The lower dielectric layer 175 comprises a second material, as a minor constituent, and the barrier ribs 180 comprise a first material as a minor constituent. The lower dielectric layer 175 and the barrier ribs 180 contain their respective minor constituents according to concentration gradients. More specifically, the lower dielectric layer 175 comprises the second material in a concentration that gradually increases in a direction toward the barrier ribs 180. The barrier ribs 180 comprise the first material in a concentration that gradually increases in a direction toward the lower dielectric layer 175.
The lower dielectric layer 175 and the barrier ribs 180 comprise compositional constituents according to concentration gradients. At portions adjacent to the interface between the lower dielectric layer 175 and the barrier ribs 180, the difference in composition of the lower dielectric layer 175 and the barrier ribs 180 is minimized, thereby preventing a poor joining or adhesion therebetween.
The discharge cells 190 are formed by the barrier ribs 180, and the phosphor layers 177 are disposed in each of the discharge cells. In order to realize full-color displays, the phosphor layers 177 are various colors. For example, when a color image is realized, using the three primary colors of light, a red phosphor layer 177R, a green phosphor layer 1770, and a blue phosphor layer 177B are alternately coated in the discharge cells 190, thereby forming red discharge cells 190R, green discharge cells 190G, and blue discharge cells 190B. A discharge gas is injected into the discharge cells. The discharge gas may be an inert gas, such as, neon (Ne), xenon (Xe), helium, or a mixture thereof.
The lower dielectric layer 175 comprises PbO as a major constituent. The lower dielectric layer 175 comprises a higher concentration of PbO, at the interface C between the lower dielectric layer 175 and the barrier ribs 180. The concentration of PbO, in the lower dielectric layer 175, increases in a direction ↓ that extends away from the interface C. The lower dielectric layer 175 comprises a concentration of ZnO that decreases in the direction ↓ away from the interface C. In other words, the lower dielectric layer 175 comprises a higher concentration of ZnO and a lower concentration of PbO, at the interface C than at an interface with the second substrate 171.
At the interface C, the concentration of ZnO is greater than the concentration of PbO. The portion of the lower dielectric layer 175, disposed close to the interface C, has properties similar to the barrier ribs 180 comprising ZnO as a major constituent. Thus adhesive strength between the lower dielectric layer 175 and the barrier ribs 180 can be increased.
In an exemplary embodiment of the present invention, the concentration gradient, of the compositional constituents of the lower dielectric layer 175, is identified. However, the present teachings are not limited thereto. The barrier ribs 180 may comprise ZnO as a major constituent, in a concentration that gradually decreases in a direction toward the lower dielectric layer 175. The barrier ribs 180 can comprise a minor constituent PbO in a concentration that gradually increases in the direction toward the lower dielectric layer 175. Both of the lower dielectric layer 175, and the barrier ribs 180 can comprise compositional constituents according to a concentration gradient.
Although the barrier rib 181 and the lower dielectric layer 176 each have a different major constituent, the interface between the lower dielectric layer 176 and the barrier rib 181 is formed to have a surface roughness, or a predetermined roughness, and thus the contact area between the lower dielectric layer 176 and the barrier rib 181 increases, thereby strengthening the adhesion therebetween.
In operation 300, a first paste layer 175a is uniformly printed, or coated, on the second substrate 171. The first paste layer 175a can be become the lower dielectric layer 175, A screen printing apparatus 200 is used to form the first paste layer 175a on the second substrate 171. The first paste layer 175a contains a first material and a second material, which have different etching selectivities with respect to an etching solution. However, a major constituent of the first paste layer 175a is a first material having a low etching selectivity. For example, the first paste layer 175a may comprise PbO, which has a low etchability with respect to a nitric acid etching solution.
In operation 302, a first drying process is performed on the second substrate 171 and the first paste layer 175a, to form a dried first paste layer 175b. The dried first paste layer 175b can be a porous membrane that is not densified like a plastic membrane.
In operation 304 a coating unit 210 is used to coat a second paste layer 180a on the dried first paste layer 175b. The second paste layer 180a can be become the barrier ribs 180. The second paste layer 180a is coated onto the dried first paste layer 175b. However, the present invention is not limited thereto, and the second paste layer 180a can be deposited by printing or another suitable process. The second paste layer 180a comprises a first material and a second material. However, a major constituent of the second paste layer 180a is the second material, which has a high etching selectivity. For example, the second paste layer 180a may comprise ZnO, which has a high etching selectivity with respect to a nitric acid etching solution.
When the second paste layer 180a is coated on the dried first paste layer 175b, the second paste layer 180a penetrates the pores of the first paste layer 175b. Accordingly, ZnO penetrates the first paste layer 175b and forms a concentration gradient. More specifically, the dried first paste layer 175b comprises a concentration of ZnO that gradually decreases in a direction toward the dried first paste layer 175b. In addition, since the ZnO penetrates the dried first paste layer 175b, the dried first paste layer 175b comprises a concentration of ZnO that gradually increases toward the first paste layer 175b, in a direction away from the interface between the first paste layer 175b and the second paste layer 180a.
In operation 306, a second drying process is performed on the second substrate 171, the dried first paste layer 175b, and/or the second paste layer 180a. Operation 306 can include plasticizing the dried first paste layer 175b and the second paste layer 180, to form a plasticized first paste layer 175c and a plasticized second paste layer 180b.
In operation 308, the plasticized second paste layer 180b is etched, using a chemical etching method, to form the ribs 180 and to expose the plasticized first paste layer 175c, thereby forming the lower dielectric layer 175. The etching shapes the ribs into a matrix. Here, the lower dielectric layer 175 comprises a first material having a lower etching selectivity than the ribs 180, as a major constituent. The lower dielectric layer 175 resists the etching, and thus, the lower dielectric layer 175 can be used as an etching stopping membrane.
The lower dielectric layer 175 comprises a compositional constituent, in a concentration that varies according to a gradient. However, the present invention is not limited thereto. The barrier ribs 180 also can be designed to comprise a compositional constituent according to a concentration gradient. After the second paste layer 180a is formed on the dried first paste layer 175b, and the second substrate 171 is turned over, the ZnO, which is a major constituent of the second paste layer 180a, penetrates the first paste layer 175b.
In operation 310, the first paste layer 176a is formed on the second substrate 171 and is not dried. In operation 312 the second paste layer 180a is directly deposited on the first paste layer 176a. The first paste layer 176a can be allowed to become semi-solid, before the second paste layer 181a is deposited on the first paste layer 176a.
In operation 314, the first paste layer 176a and the second paste layer 181a are dried and plasticized at the same time, to form a plasticized first paste layer 176b and a plasticized second paste layer 180b. The interface between plasticized first paste layer 176b and the plasticized second paste layer 181b can be formed to have a surface roughness. Therefore, the contact area between the lower dielectric layer 175 and the plasticized second paste layer 181b is increased, and the adhesive strength, of a bond therebetween, is increased.
In operation 316, the plasticized second paste layer 181b is etched, using a chemical etching method, as in
As described above, in the aspects of the present invention, each of a dielectric layer and a barrier rib disposed to contact the dielectric layer, comprise a first material and a second material, wherein the first and second materials have different etching selectivities, according to concentration gradient of the first and second materials. The difference in concentration between the first material and the second material is reduced at the interface between the dielectric layer and the barrier rib, thereby improving the adhesive strength of a bond between the dielectric layer and the barrier rib. In addition, since the interface between the dielectric layer and the barrier rib is formed to have a surface roughness, the contact surface is increased, and thus, the adhesive strength of the bond is improved. Therefore, since adhesive strength between the dielectric layer and the barrier rib is increased, the dielectric layer can be prevented from being damaged, cell defects can be prevented due to void formation, and voltage tolerance can be maintained. Thus, a PDP having improved reliability can be provided.
Moreover, a drying process can be omitted, so that a PDP can be easily manufactured. The dielectric layer and the barrier rib included therein can comprise a first material and a second material according to a concentration gradient Also, a drying and plasticizing process can be omitted, so that the PDP can be easily manufactured with the interface of the dielectric layer and the barrier rib having a surface roughness.
Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents. As used herein, the phrase “at least one” refers to a single component or multiple components following the phrase.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-30365 | Mar 2007 | KR | national |
