BAE, Bum Jin (Lg Electornics Inc. Ip Group, 16 Woomyeon-Dong Seocho-Gu, Seoul 137-724, KR)
KIM, Je Seok (Lg Electornics Inc. Ip Group, 16 Woomyeon-Dong Seocho-Gu, Seoul 137-724, KR)
MOON, Eun A (Lg Electornics Inc. Ip Group, 16 Woomyeon-Dong Seocho-Gu, Seoul 137-724, KR)
HONG, Gun Young (Lg Electornics Inc. Ip Group, 16 Woomyeon-Dong Seocho-Gu, Seoul 137-724, KR)
BAE, Bum Jin (Lg Electornics Inc. Ip Group, 16 Woomyeon-Dong Seocho-Gu, Seoul 137-724, KR)
KIM, Je Seok (Lg Electornics Inc. Ip Group, 16 Woomyeon-Dong Seocho-Gu, Seoul 137-724, KR)
MOON, Eun A (Lg Electornics Inc. Ip Group, 16 Woomyeon-Dong Seocho-Gu, Seoul 137-724, KR)
Claims
[ 1 ] A plasma display panel comprising : a first substrate induing a plurality of bus electrodes, a first dielectric layer, a first protective film formed on the first dielectric layer, and a second protective film formed on the first protective layer, which contains single crystalline powder colored with different colors except white; and a second substrate combined with the first substrate by interposing a barrier rib therebetween, which includes at least one address electrode, a second dielectric layer and a phosphor layer. [2] The plasma display panel according to claim 1, wherein the single crystalline powder is MgO powder colored with a color having a reflection rate of less than
90% relative to white. [3] The plasma display panel according to claim 2, wherein the MgO powder isdoped with at least one selected from a group consisting praseodymium (Pr), europium (Eu), cobalt (Co), chromium (Cr), manganese (Mn), thulium (Tm) and samarium (Sm) so as to have colored appearance. [4] The plasma display panel according to claim 3, wherein at least one selected from a group consisting of Pr, Eu, Co, Cr, Mn, Tm and Sm is doped in an amount of 5 to 20 mol% to Mg content of the MgO powder. [5] A process for fabrication of a plasma display panel comprising: forming a plurality of bus electrodes and a first dielectric layer on a first substrate; forming a first protective film on the first dielectric layer; forming a second protective film, which contains single crystalline powder colored with different colors except white, on the first protective film; and combining the prepared first substrate with a second substrate having an address electrode. [6] The process according to claim 5, wherein the single crystalline powder is MgO powder colored with a color having a reflection rate of less than 90% relative to white. [7] The process according to claim 6, wherein the MgO powder is doped with at least one selected from a group consisting Pr, Eu, Co, Cr, Mn, Tm and Sm so as to have a colored appearance. [8] The process according to claim 7, wherein at least one selected from a group consisting of Pr, Eu, Co, Cr, Mn, Tm and Sm is doped in an amount of 5 to 20 mol% to Mg content of the MgO powder.
[9] A plasma display panel comprising: a first substrate having a plurality of discharge electrodes; a second substrate having an address electrode; and a barrier rib interposed between the first substrate and the second substrate, which contains MgO powder colored with different colors except white.
[10] The plasma display panel according to claim 9, wherein the MgO powder colored with a color having a reflection rate of less than 90% relative to white.
[11] The plasma display panel according to claim 10, wherein the MgO powder is doped with at least one selected from a group consisting Pr, Eu, Co, Cr, Mn, Tm and Sm so as to have a colored appearance.
[12] A process for fabrication of a plasma display panel comprising: forming a first substrate having a plurality of discharge electrodes; forming a second substrate having an address electrode; and forming a barrier rib between the first substrate and the second substrate, which contains MgO powder colored with different colors except white.
[13] A plasma display panel comprising: a first substrate having a plurality of bus electrodes; and a second substrate combined with the first substrate by interposing a barrier rib therebetween, which includes at least one address electrode, a dielectric layer and a phosphor layer containing MgO powder colored with different colors except white.
[14] The plasma display panel according to claim 13, wherein the MgO powder is colored with a color having a reflection rate of less than 90% relative to white.
[15] A process for fabrication of a plasma display panel comprising: forming a first substrate having a plurality of bus electrodes; and forming a second substrate combined with the first substrate by interposing a barrier rib therebetween, wherein a phosphor layer containing MgO powder colored with different colors except white is provided in the barrier rib. |
Description
PLASMA DISPLAY PANEL AND PROCESS OF MANUFACTURING THE SAME
Technical Field
[1] The present invention relates to display device and, more particularly, to a plasma display panel.
Background Art [2] In an age of multimedia, there is a requirement for development of display devices capable of expressing natural color- like colors (often referred to as "natural true color") with increased size and improved fine resolution. [3] However, since Cathode Ray Tube (CRT) as a traditional system has restrictions in fabricating a large screen of at least 40 inches, more advanced technologies such as liquid crystal display (LCD), plasma display panel (PDP), projection TV, etc. rapidly continue in progress toward high-definition image processing applications. [4] A display device such as a PDP has significant features such as considerably small thickness compared to CRT as a self-emissive device, is easily fabricated as a high quality magnificent flat screen of 60 to 80 inches, and is clearly distinguished from typical CRTs in aspects of style and design thereof. [5] The PDP normally comprises a base plate having an address electrode, a top plate having a pair of sustain electrodes, and a discharge cell defined by a barrier rib wherein an inner side of the discharge cell is coated with a fluorescent material so as to display an image thereon. [6] More particularly, UV rays generated by plasma discharge occurring in a discharge space between the top and base plates may be incident into a phosphor material applied to an inner side of the discharge cell, thereby emitting visible light, which in turn, displays images thereon.
Disclosure of Invention
Technical Problem [7] An object of the present invention is to provide a plasma display panel which may improve secondary electron emission effects to reduce emission voltage and may control plasma discharge so as to enhance display efficiency thereof, as well as a process for fabrication thereof. [8] Another object of the present invention is to provide a plasma display panel a plasma
display panel which may reduce reflected luminescence to increase light-room contrast, as well as a process for fabrication thereof. Technical Solution
[9] To achieve these objects and other advantages and in accordance with the purpose of the invention, a plasma display panel according to a first embodiment of the present invention comprises: a first substrate induing a plurality of bus electrode, a first dielectric layer, a first protective film formed on the first dielectric layer, and a second protective film containing single crystalline powder colored with different colors except white, which is formed on the first protective film; and a second substrate combined with the first substrate by interposing a barrier rib therebetween, which includes at least one address electrode, a second dielectric layer, and a phosphor layer.
[10] A process for fabrication of the plasma display panel according to the first embodiment of the present invention comprises: forming a plurality of bus electrodes and a first dielectric layer on a first substrate; forming a first protective film on the first dielectric layer; forming a second protective film, which contains single crystalline powder colored with different colors except white, on the first protective film; and combining the prepared first substrate with a second substrate having an address electrode.
[11] As a second embodiment of the present invention, there is provided a plasma display panel comprising: a first substrate having a plurality of discharge electrodes; a second substrate having an address electrode; and a barrier rib interposed between the first substrate and the second substrate, which contains MgO powder colored with different colors except white.
[12] A process for fabrication of the plasma display panel according to the second embodiment of the present invention comprises: forming a first substrate having a plurality of discharge electrodes; forming a second substrate having an address electrode; and forming a barrier rib between the first substrate and the second substrate, which contains MgO powder colored with different colors except white.
[13] As a third embodiment of the present invention, there is further provided a plasma display panel comprising: a first substrate having a plurality of bus electrodes; and a second substrate combined with the first substrate by interposing a barrier rib therebetween, which includes at least one address electrode, a dielectric layer and a phosphor layer containing MgO powder colored with different colors except white.
[14] A process for fabrication of the plasma display panel according to the third embodiment of the present invention comprises: forming a first substrate having a
plurality of bus electrodes; forming a second substrate combined with the first substrate by interposing a barrier rib therebetween, wherein a phosphor layer containing MgO powder colored with different colors except white is provided in the barrier rib.
[15] 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
Advantageous Effects
[16] Functional effects of a plasma display panel and a process for fabrication thereof according to the present invention will become apparent from the following description.
[17] First, secondary electron emission effects of a protective film, a phosphor layer and a barrier rib which all are exposed to a discharge space during driving of a plasma display panel are improved
[18] Second, secondary electron emission effects of a plasma display panel are improved, such that a firing voltage (for initiating the discharge) is decreased, a discharge retardation time is shortened and reflected luminescence is reduced, thus enhancing light-room contrast. Brief Description of the Drawings
[19] The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention.
[20] In the drawings:
[21] FIG. 1 is a constructional view illustrating a plasma display panel according to an exemplary embodiment of the present invention;
[22] FIG. 2 illustrates a driving device and a connection part of a plasma display panel according to the present invention;
[23] FIG. 3 illustrates a wiring structure of a substrate for a tape carrier package according to the present invention;
[24] FIG. 4 is a schematic view illustrating a plasma display device according to another exemplary embodiment of the present invention;
[25] FIGs. 5 to 7 are schematic views sequentially illustrating a process for fabricating a front substrate of a plasma display device according to an exemplary embodiment of the present invention;
[26] FIGs. 8 to 13 are schematic views sequentially illustrating a process for fabricating a back substrate of a plasma display device according to an exemplary embodiment of the present invention;
[27] FIG. 14 illustrates a process of combining a front substrate with a back substrate of a plasma display panel; and
[28] FIG. 15 is a cross-sectional view taken along the line A-A' of FIG. 14.
Mode for the Invention
[29] Hereinafter, other purposes, characteristics and other beneficial features of the present invention will become apparent from the following detailed description with reference to illustrative examples, taken in conjunction with the accompanying drawings.
[30] Exemplary embodiments of the present invention to achieve the above objects will be described in detail in the following description with reference to the accompanying drawings.
[31] In order to clarify a number of layers and/or regions in a plasma display panel, a thickness of each layer is enlarged in the drawings. Therefore, a thickness ratio between adjacent layers shown in the drawings is not to be construed as a true thickness ratio.
[32] A plasma display panel of the present invention may have a protective film with a two-layered structure. Hereinafter, a protective film formed adjacent to a first dielectric layer 190 of a front substrate 170 refers to a first protective film 195a, while another film formed on the first protective film 195a and facing a discharge space refers to a second protective film 195b.
[33] FIG. 1 is a constructional view illustrating a plasma display panel according to an exemplary embodiment of the present invention.
[34] As illustrated in FIG. 1, a plasma display panel of the present invention comprises a front substrate 170 wherein a scan electrode 180a and a sustain electrode 180b, which both are made of indium tin oxide (ITO), as well as bus electrodes 180a' and 180b' made of common metal materials may be formed in a single direction on the front substrate 170.
[35] A first dielectric layer 190 and a protective film are formed on the front substrate in this order while covering the scan electrode, the sustain electrode and the bus electrodes.
[36] The front substrate 170 may be formed by milling and/or cleaning a glass material used for a display panel.
[37] The scan electrode 180a and the sustain electrode 180b may be formed by photo- etching ITO or SnO 2 through sputtering and/or by a lift-off process through CVD.
[38] The bus electrodes 180a' and 180b' may contain Ag. Each of the scan electrode and the sustain electrode may have a black matrix, which comprises a low melting point glass and a black pigment.
[39] A first dielectric layer 190 may be formed on the front substrate 170 on which the scan electrode, the sustain electrode and the bus electrodes are provided The first dielectric layer 190 may include a low melting point transparent glass with a specific constitutional composition described below.
[40] In order to protect the first dielectric layer from impact of positively charged (+) ions during discharge, a protective film comprising MgO is formed on the first dielectric layer 190. This protective film may increase secondary electron emission. Hereinafter, the protective film will be described in greater detail.
[41] The protective film according to an exemplary embodiment of the present invention may include a first protective film 195a containing an MgO thin film and a second protective film 195b formed on the first protective film 195, which contains single crystalline MgO powder.
[42] If a dopant is added to the first protective film 195a, a jitter value of an address period may be reduced On the other hand, when a content of the dopant in the first protective film increases over a certain level, the jitter value may also be improved
[43] The dopant is preferably added in a certain amount effective to minimize the jitter value. The optimal content of the dopant in the first protective film 195a may range from 20 to 500 ppm. In order to reduce the jitter value, other materials may be used as the dopant in place of silicon.
[44] The first protective film 195a preferably has a thickness of 300 to 700nm. If the thickness is less than 300nm, undesired discharge may occur. When the thickness exceeds 700nm, problems in production process and production costs may be caused
[45] A second protective film 195b may be formed on the first protective film 195a. The second protective film 195b may contain single crystalline MgO powder. "Size" referred herein means a diameter for a spherical crystal and/or a length of one side for a cubic crystal.
[46] The second protective film 195b may be partially formed on the first protective film
195a, rather than over the whole area thereof. Briefly, as illustrated in FIG. 1, the second protective film 195b may be irregularly (or discontinuously) formed on the first protective film 195a and may occupy about 30 to 80% of a surface area of the first
protective film 195a.
[47] As a result, the second protective film 195b irregularly formed on the first protective film 195a may increase the total surface area of the protective film so as to improve secondary electron emission.
[48] A size of the single crystalline MgO power contained in the second protective film
195b may range from 50 to l,000nm and the single crystalline MgO powder may have a maximum cathode luminescence at a wavelength of 300 to 500nm.
[49] Accordingly, since the single crystalline MgO powder is formed in an aggregate form on a part of the first protective film 195a, the surface of the protective film is not entirely smooth, instead being irregular. As a result, a gas discharge in the plasma display panel may increase a surface area of the panel on which UV ions impact the protective film so as to increase secondary electron emission while decreasing a firing voltage (initiating discharge), thereby improving discharge efficiency and reducing a jitter value.
[50] The second protective film 195b may have a thickness of 100 to 300nm. If the thickness is less than lOOnm, it is difficult to form crystalline MgO powder. When the thickness exceeds 300nm, problems in production process and production costs may be caused
[51] However, the single crystalline MgO powder contained in the second protective film
195b is white in color so that reflected luminescence of the display panel may be increased during gas discharge, causing a problem of lowered light-room contrast.
[52] According to the present invention, the single crystalline MgO powder contained in the second protective film 195b is given different colors except white, thereby reducing reflected luminescence and improving light-room contrast of the display panel.
[53] More particularly, according to the present invention, the single crystalline MgO powder is doped with at least one metal ion selected from a group consisting of praseodymium (Pr), europium (Eu), cobalt (Co), chromium (Cr), manganese (Mn), thulium (Tm) and samarium (Sm) in a certain amount such that the single crystalline MgO powder is colored by the doped metal ion.
[54] The numerical symbol 195c represents the single crystalline MgO powder colored by the metal ion.
[55] In addition, the numerical symbol 195d shows non-single crystalline MgO powder colored by the metal ion, which is included in the barrier rib 140 and the phosphor layer 150.
[56] The metal ion used herein may include at least one selected from Pr, Eu, Co, Cr, Mn,
Tm and Sm, however, the present invention is not particularly limited thereto. Preferably, the metal ion may include metal ions with various colors having a reflection rate of less than 90% relative to white.
[57] As such, since the MgO powder used in the present invention is colored by the metal ions described above, the MgO powder preferably enhances discharge effects while reducing reflected luminescence, thereby improving light-room contrast of the display panel.
[58] The MgO powder contained in the second protective film 195b and the metal ion doped inside the second protective film 195b will be described in greater detail below.
[59] On a surface of the back substrate 110, an address electrode 120 is partially formed in a direction crossing the sustain electrode pair. In addition, a white second dielectric layer 130 is formed throughout the surface of the back substrate while covering the address electrode 120.
[60] The second dielectric layer 130 may be applied to the back substrate by printing or film laminating and may be completed by a firing process.
[61] At least one barrier rib 140 is arranged between adjacent address electrodes 120 above the dielectric layer 130. Such a barrier rib 140 may include stripe type, well type and/or delta type ribs.
[62] Red (R), green (G) and blue (B) phosphor layers (150a, 150b, 150c) are formed between adjacent barrier ribs 140, respectively. Intersection points between the address electrode 120 on the back substrate 110 and the sustain electrode pair on the front substrate 110 may construct discharge cells.
[63] In this regard, the protective film of the front substrate 170, the barrier rib 140 and the phosphor layers 150a, 150b and 150c are exposed to a discharge space.
[64] For this reason, like the second protective film 195b in the front substrate 170, the barrier rib 140 as well as the phosphor layers 150a, 150b and 150c may contain single crystalline MgO powder, which is colored by doping metal ions such as Pr, Eu, Co, Cr, Mn, Tm or Sm in a certain level thereon, so as to reduce reflected luminescence and improve light-room contrast.
[65] The front substrate 170 is combined with the back substrate 110 by interposing the barrier rib 140 therebetween and using a sealant provided around an outer side of the substrates.
[66] The front substrate 170 and the back substrate 110 may be connected to a driving device.
[67] FIG. 2 illustrates a driving device and a connection part of a plasma display panel according to the present invention. [68] As illustrated in FIG. 2, the whole plasma display device 210 of the present invention may include a panel 220, a driving substrate 230, and a tape carrier package
(hereinafter, referred to as "TCP") 240 which is a flexible substrate to connect a plurality of electrodes placed in cells of the panel 220 to the driving substrate 230. [69] The panel 220 comprises the front substrate 170, the back substrate 110 and the barrier rib 140, as described above. [70] Electrical and physical connection of the panel 220 to the TCP 240 and electrical and physical connection of the TCP 240 to the driving substrate 230 may be embodied using an anisotropic conductive film (hereinafter, referred to as "ACF"). [71] The ACF is a conductive resin film prepared using a nickel (Ni) ball coated with gold
(Au). [72] FIG. 3 illustrates a wiring structure of a substrate for a tape carrier package according to the present invention. [73] As illustrated in FIG. 3, a TCP 240 plays a role of connecting the panel 220 and the driving substrate 230 and has a driver chip mounted thereon. [74] More particularly, the TCP 240 comprises a wiring 243 compactly arranged on the flexible substrate 242 and a driver chip 241 connected to the wiring 243, which receives electric power from the driving substrate 230 and supplies the electric power to a particular electrode mounted on the panel 220. [75] The driver chip 241 has a specific structure of receiving applied low voltage and driving control signals, and then, alternating and outputting a number of high-powered signals. Therefore, the driver chip has a small number of wirings at a part connected to the driving substrate 230 and a relatively large number of wirings at the other part connected to the panel 220. [76] The wiring of the driver chip 241 may be connected through a space formed at the driving substrate side. The wiring 243 may not be defined by a barrier based on the center of the driver chip 241. [77] FIG. 4 is a schematic view illustrating a plasma display device according to another exemplary embodiment of the present invention. [78] In an exemplary embodiment of the present invention, the panel 220 is connected to the driving device through a flexible printed circuit (hereinafter, referred to as "FPC")
250. [79] The FPC 250 is a film having a pattern formed therein using polyimide. The FPC
250 and the panel 220 are connected to each other by the ACF. The driving substrate 230 used in this embodiment is a PCB.
[80] The driving device may include a data driver, a scan driver and/or a sustain driver.
[81] The data driver is connected to the address electrode to apply data pulses thereto.
Likewise, the scan driver is connected to the scan electrode to provide Ramp-up and/or Ramp-down waveforms, scan pulse and sustain pulse thereto. In addition, the sustain driver applies sustain pulse and DC voltage to a sustain common electrode.
[82] Driving operation of the plasma display panel is divided into three periods, that is, a reset period, an address period and a sustain period
[83] During the reset period, Ramp-up waveform is simultaneously applied to plural scan electrodes. During the address period, a negative scan pulse is applied to the scan electrodes in order while synchronizing with a scan pulse to apply a positive data pulse to plural address electrodes in sequence. Lastly, a sustain pulse is alternately applied to the scan electrodes and the sustain electrodes during a sustain period
[84] Hereinafter, the plasma display panel of the present invention will be described in greater detail in the following description of examples with reference to the accompanying drawings.
[85] [FIRST EMBODIMENT]
[86] FIGs. 5 to 7 are schematic views sequentially illustrating a process for fabricating a front substrate of a plasma display device according to an exemplary embodiment of the present invention.
[87] In this example, doping at least one metal ion selected from a group consisting of Pr,
Eu, Co, Cr, Mn, Tm and Sm in a certain amount on the second protective film 195b, single crystalline MgO powder contained in the second protective film is colored by the doped metal ion so that the display panel exhibits a reduction in reflected luminescence and improved light-room contrast.
[88] Referring to FIGs. 5 to 7, a process for fabricating a front substrate 170 of a plasma display panel according to Example 1 will be described in detail.
[89] Firstly, as illustrated in FIG. 5, a scan electrode 180a, a sustain electrode 180b and bus electrodes 180a and 180b are formed on the front substrate 170.
[90] The front substrate 170 may be fabricated by milling a glass for a display substrate or a soda lime glass, and then, cleaning the same.
[91] The scan electrode 180a and the sustain electrode 180b may be formed by photo- etching ITO through sputtering.
[92] Alternatively, the scan electrode 180a and the sustain electrode 180b may be formed
by ion plating ITO or vacuum deposition thereof.
[93] The scan electrode 180a and the sustain electrode 180 may also be formed using SnO
2 by a lift-off process through CVD.
[94] As for the photo-etching of ITO to form the scan electrode 180a and the sustain electrode 180b, the ITO is deposited on the front substrate 170. Next, photoresist is applied to the deposited ITO, followed by drying the photoresist coated ITO. Placing a patterned photo^nask on the photoresist and irradiating light, the photoresist is exposed After the exposure, the uncured part is developed and etched to form the scan electrode 180a and the sustain electrode 180b.
[95] As for the lift-off process of SnO 2 to form the scan electrode 180a and the sustain electrode 180b, after photoresist is applied to the front substrate 170, placing a patterned photo^nask on the applied photoresist and irradiating light, the photoresist is exposed After exposure, the uncured part is developed After the developing process, SnO 2 is deposited to the front substrate and the photoresist is released, thus forming the scan electrode 180a and the sustain electrode 180b.
[96] Each of the scan electrode 180a and the sustain electrode 180 may have a black matrix, which includes a low melting point glass and a black pigment.
[97] The bus electrodes 180a' and 180b' may be formed using Ag by screen printing or a photosensitive paste method
[98] Alternatively, the bus electrodes 180a' and 180b' may be formed by photo-etching
Cr/Cu/Cr or Cr/Al/Cr through sputtering.
[99] As for the screen printing to form the bus electrodes 180a' and 180b' a conductive paste such as Ag is printed on the front substrate 170 through a screen mask, followed by drying and firing the processed front substrate to form the bus electrodes.
[100] As for the photosensitive paste method to form the bus electrodes 180a' and 180b' photosensitive Ag is printed and applied to the front substrate 170, followed by drying the processed front substrate. After that, placing a patterned photo-mask on the Ag coating and irradiating light, the Ag coating is exposed After the exposure, the uncured part is developed After the developing process, the resultant substrate is dried and fired, thus forming the bus electrodes 180a' and 180b'.
[101] As for the photo-etching process to form the bus electrodes 180a' and 180b' Cr/Cu/Cr or Cr/Al/Cr is deposited on the front substrate 180 and photoresist is applied to the deposited Cr/Cu/Cr or Cr/Al/Cr, followed by drying the same. After that, placing a patterned photo^nask on the photoresist and irradiating light, the photoresist is exposed After the exposure, the uncured part is developed and etched to form the bus
electrodes 180a' and 180b'.
[102] The scan electrode 180a, the sustain electrode 180b, and the bus electrodes 180a' and 180b' are substantially discharge electrodes, therefore, the plasma display panel of the present invention may include the discharge electrode consisting of only the bus electrodes 180a' and 180b' without the scan electrode 180a and the sustain electrode 180b.
[103] Subsequently, as illustrated by FIG. 6, a first dielectric layer 190 is formed on the front substrate 170 on which the scan electrode 180a, the sustain electrode 180b and the bus electrodes 180a' and 180b' are formed
[104] The first dielectric layer 190 may be formed using a low melting point glass by screen printing, use of a coater, and/or lamination of a green sheet.
[105] The coater may be a roll or a slot.
[106] Following this, as illustrated in FIG. 7, a protective film according to the present invention is formed on the first dielectric layer 190.
[107] The protective film of the present invention primarily includes a first protective film 195a and a second protective film 195b.
[108] The first protective film 195a is formed on the first dielectric layer 190 and may contain a dopant such as silicon (Si). The first protective film 195a may be formed by chemical vapor deposition (CVD), an electron beam (E-beam) method, ion-plating, a sol-gel method, and/or sputtering.
[109] If the first protective film 195a is doped with Si, a jitter value of an address period may be reduced On the other hand, when Si content in the first protective film increases over a certain level, the jitter value may be increased Therefore, Si is preferably doped on the first protective film in a certain amount sufficient to minimize the jitter value. The optimal Si content in the first protective film may range from 20 to 500 ppm. In order to reduce the jitter value, other materials may be used as the dopant in place of Si.
[110] A second protective film 195b is formed on the first protective film 195b, as shown in FIG. 7.
[I l l] The second protective film 195b preferably comprises single crystalline MgO powder. The single crystalline MgO powder may have a size of 50 to l,000nm. "Size" referred herein means a diameter for a spherical crystal and/or a length of one side for a cubic crystal. "Single crystalline" referred herein means a solid state wherein all crystals are regularly generated and aligned along a crystal axis and should be distinguished from "poly-crystalline" as a population of small different single crystals
with different orientations.
[112] According to first embodiment of the present invention, the second protective film 195b is doped with at least one metal ion selected from a group consisting of Pr, Eu, Co, Cr, Mn, Tm and Sm in a certain amount so that single crystalline MgO powder contained in the second protective film 195b is colored by the doped metal ion.
[113] Doping Pr on the single crystalline MgO powder, the second protective film 195b exhibits a dark brown color. Similarly, Eu doping develops a bright red color, Co or Cr doping develops a blue color, Mn doping develops a brown color, Tm doping develops a grey color, and Sm doping develops a bright red color on the second protective film 195b.
[114] The numerical symbol 195c represents the single crystalline MgO powder in the second protective film 195b colored by the metal ion.
[115] Hereinafter, a process for fabricating the second protective film 195b containing single crystalline MgO powder and the metal ion described above will be described in detail by the following description.
[116] Firstly, as illustrated in FIG. 7, at least one selected from a group consisting of Pr,
Eu, Co, Cr, Mn, Tm and Sm, a dispersing agent and single crystalline MgO powder are mixed together. Next, the mixture is sprayed on the first protective film 195a and dried to form the second protective film 195b. Herein, in order to improve adhesion of the single crystalline MgO powder to the first protective film 195a, a cross-linking agent such as TiO may be added to the mixture. An amount of the single crystalline MgO powder may range from 1 to 30wt% while an amount of the dispersing agent may range from 70 to 99wt.%. At least one selected from a group consisting of Pr, Eu, Co, Cr, Mn, Tm and Sm may be doped in an amount of 5 to 20 mol% to Mg content in the single crystalline MgO powder. The dispersing agent may include acryl, epoxy, urethane, acrylic urethane, alkyd, a polyamide polymer, poly carboxylic acid and/or mixtures thereof.
[117] The following description will be given of discharge voltage and reflection rate when a metal ion is doped inside the second protective film 195b according to the present invention, with reference to Table 1.
[118] Table 1
[Table 1] [Table ]
[119] Table 1 shows discharge voltages (V) and reflection rates (%) when each of Pr, Eu, Co, Cr, Mn, Tm and Sm is doped inside the second protective film 195b in an amount of 5%, 10%, 15% and 20%, respectively. The doping amount is defined relative to 100wt.% of single crystalline MgO powder contained in the second protective film 195b.
[120] As described above, doping each of Pr, Eu, Co, Cr, Mn, T and Sm on the second protective film 195b, single crystalline MgO powder contained in the second protective film 195b is colored by the doped metal ion. As a result, it can be seen that reflection rate of the protective film is reduced while improving light-room contrast thereof.
[121] [SECOND EMBODIMENT]
[122] FIGs. 8 to 13 are schematic views sequentially illustrating a process for fabricating a back substrate of a plasma display device according to an exemplary embodiment of the present invention.
[123] Firstly, as illustrated in FIG. 8, an address electrode 120 is formed on a back substrate 110. The back substrate 110 may be fabricated by milling and/or cleaning a glass for a display substrate or a soda lime glass.
[124] The address electrode 120 may be formed using Ag by screen printing or a photosensitive paste method.
[125] Alternatively, the address electrode 120 may be formed by photo-etching Cr/Cu/Cr
or Cr/Al/Cr through sputtering.
[126] In this regard, as for the screen printing to form the address electrode 120, a conductive paste such as Ag is printed on a back substrate 110 through a screen mask, followed by drying and firing the back substrate to form the address electrode.
[127] As for the photosensitive paste method to form the address electrode 120, photosensitive Ag is printed and applied to the back substrate 110, followed by drying the back substrate. After that, placing a patterned photo-mask on the Ag coating and irradiating light, the Ag coating is exposed. After the exposure, the uncured part is developed. After the developing process, the resultant substrate is dried and fired, thus forming the address electrode 120.
[128] In addition, as for the photo-etching process to form the address electrode 120, Cr/
Cu/Cr or Cr/Al/Cr is deposited on the back substrate 110. Photoresist is applied to the deposited Cr/Cu/Cr and Cr/Al/Cr, and then, is dried. Next, placing a patterned photomask on the photoresist and irradiating light, the photoresist is exposed. After the exposure, the uncured part is developed and etched, thus forming the address electrode 120.
[129] Continuously, as illustrated in FIG 9, a second dielectric layer 130 may be formed using a low melting point glass and a filler such as TiO 2 by screen printing, use of a coater, and/or lamination of a green sheet. The coater may be a roll or a slot.
[130] Continuously, as illustrated in FIGs. 10 to 12, discharge cells are isolated from each other by barrier ribs.
[131] The barrier rib 140a used in second embodiment of the present invention, may include: 50 to 80wt.% of parent glass; 15 to 30wt.% of filler; and 5 to 20wt.% of MgO powder 195d, which is doped with at least one selected from a group consisting of Pr, Eu, Co, Cr, Mn, Tm and Sm.
[132] The parent glass may include PbO, SiO 2 , B 2 O 3 and/or Al 2 O 3 , while the filler may include TiO 2 and Al 2 O 3 .
[133] At least one selected from a group consisting of Pr, Eu, Co, Cr, Mn, Tm and Sm may be doped in an amount of 5 to 20 mol% to Mg content in the MgO powder 195d
[134] After a vehicle (including a binder and/or a solvent) is added to the barrier rib material 140a in order to prepare a paste 140a for fabricating the barrier rib (sometimes, referred to as "barrier rib paste") according to the present invention, as illustrated in FIG. 6C, the barrier rib paste 140a is applied to the second dielectric layer 130, and then, dried for a desired time period.
[135] Following this, the applying and drying processes are repeatedly conducted to obtain
a certain thickness (for example, 150 to 200/M). Then, patterning the barrier rib 140a results in a completed barrier rib 140 according to second embodiment of the present invention. [136] The patterning process may performed by placing a mask 155 on the substrate, exposing the mask and developing the same. [137] More particularly, placing a mask 155 on a part of the substrate corresponding to the address electrode and exposing the same, a light irradiated part remains only on the substrate and forms the barrier rib 140. [138] As described above, according to second embodiment of the present invention, the
MgO powder 195d colored by doping at least one of Pr, Eu, Co, Cr, Mn, Tm and Sm is included in the barrier rib material 140a to fabricate the barrier rib 140, improving discharge efficiency while reducing jitter values. [139] In addition, since MgO powder 195d colored by doping at least one of Pr, Eu, Co,
Cr, Mn, Tm and Sm is included in the barrier rib 140, reducing reflected luminescence while improving light-room contrast. [140] [THIRD EMBODIMENT] [141] As illustrated in FIG. 13, phosphors 150a, 150b and 150c are applied to an area among the second dielectric layer 130 in contact with a discharge space and lateral sides of the barrier rib 140, so as to form a phosphor layer 150. [142] More particularly, the phosphor layer 150 is formed by applying R, G and B phosphors to corresponding discharge cells, respectively. The phosphor application may be conducted by screen printing or a photosensitive paste method [143] The phosphors 150a, 150b and 150c may comprise 80 to 95wt% of red, green and blue phosphor materials, respectively, as well as 5 to 20wt.% of MgO powder 195d colored by doping at least one selected from Pr, Eu, Co, Cr, Mn, Tm and Sm thereon. [144] Mostly, the red phosphor material R comprises (Y, Gd)BO 3 :Eu3 + , the green phosphor material G comprises Zn 2 Si0 4 :Mn2 + , and the blue phosphor material B comprises
BaMgAl 10 O 17 :Eu2 + . [145] An amount of at least one selected from Pr, Eu, Co, Cr, Mn, Tm and Sm may range from 5 to 20 mol% to Mg content of the MgO powder 195d [146] As described above, according to third embodiment of the present invention, the
MgO powder 195d colored by doping at least one of Pr, Eu, Co, Cr, Mn, Tm and Sm is included in the phosphor materials 150a, 150b and 150c to form the phosphor layer
150, improving discharge efficiency while reducing jitter values. [147] In addition, since MgO powder 195d colored by doping at least one of Pr, Eu, Co,
Cr, Mn, Tm and Sm is included in the phosphor layer 150, reflected luminescence is reduced while light-room contrast is improved [148] Next, the front substrate 170 completed by a process illustrated in FIG. 5 is adhered and sealed to the back substrate 110 by interposing the barrier rib 140 therebetween.
After removing impurities from the substrates, Xe + Ne, Xe + He or Xe + Ne + He discharge gas is introduced to discharge cells in the barrier rib 140, followed by sealing so as to complete a plasma display panel as shown in FIG. 1 according to the present invention. [149] The following description will be given of a sealing process of the front substrate
170 and the back substrate 110. [150] The sealing process may commonly be conducted by screen printing or a dispensing method [151] As for the screen printing, a patterning screen is placed a certain distance above a substrate, a paste forming a sealant is pressed on the screen to be transcribed, so as to print the sealant in a desired shape. Screen printing has merits of using a simple production system and high use efficiency of raw materials. [152] As for the dispensing method, using CAD wiring data typically used for manufacture of a screen mask, a thick film paste is directly injected over a substrate under air pressure so as to form a sealant. The dispensing method is advantageous in that production costs of a mask are reduced and the thick film has A high degree of freedom in shaping. [153] FIG. 14 illustrates a process of combining a front substrate with a back substrate of a plasma display panel.
[154] FIG. 15 is a cross-sectional view taken along the line A-A' of FIG. 14. [155] As illustrated in these figures, a sealant 600 is applied to the front substrate 170 and the back substrate 110. More particularly, simultaneously printing or dispensing the sealant at a certain distance from the outmost side of each substrate, the sealant is applied to the substrates. [156] Continuously, the sealant is subjected to firing. During the firing, organic materials contained in the sealant are removed and the front substrate 170 is combined with the back substrate 110. [157] During the firing, a width of the sealant may be increased while a thickness of the sealant may be reduced [158] Although the sealant 600 is printed or coated according to the above example, the sealant may be adhered to the front substrate 170 or the back substrate 110 in the form
of a sealing tape. Acϋtionally, an ageing process is performed at a desired temperature so as to improve characteristics of the protective film.
[159] A front filter may be formed on the front substrate 170.
[160] The front filter may have an electromagnetic interference (EMI) shielding film to prevent EMI from being emitted from the display panel. Coating the front filter with a conductive material patterned in a specific form, the front filter may ensure high visible light transmittance required for a display device while shielding EMI.
[161] In aάϊtion, the front filter may have a near infrared shielding film, a color compensation film and/or an anti-reflection film.
[162] Although technical constructions and other features of the present invention have been described, it will be apparent to those skilled in the art that the present invention is not limited to the exemplary embodiments and accompanying drawings described above but may cover substitutions, variations and/or modifications thereof without departing from the sprit or scope of the invention.
[163] Accordingly, the present invention is not restricted to the contents illustrated in the above description but is construed to come within the scope of the invention defined in the appended claims and their equivalents.
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