Patent Publication Number: US-2005116642-A1

Title: Plasma display panel and method of manufacturing the same

Description:
CLAIM OF PRIORITY  
      This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. § 119 from an application entitled PLASMA DISPLAY PANEL AND METHOD OF MANUFACTURING THE SAME filed with the Korean Intellectual Property Office on 29 Nov. 2003, and there duly assigned Serial No. 2003-86112.  
     BACKGROUND OF THE INVENTION  
      1. Technical Field  
      The present invention generally relates to a plasma display panel and a method of manufacturing the same and, in particular, to a plasma display panel and a method of manufacturing the same wherein electrodes are formed on a panel substrate using an offset printing technique.  
      2. Description of Related Art  
      Generally, a plasma display panel (PDP) is a display device which displays images using plasma discharge. When voltage is applied to electrodes arranged within discharge spaces of the PDP, the plasma discharge takes place between the electrodes while generating vacuum ultraviolet (VUV) rays. The ultraviolet rays excite phosphors in a predetermined pattern, thereby displaying desired images.  
      PDPs are largely classified into AC, DC, and hybrid type PDPs. With the AC PDP, address electrodes are formed on a rear substrate in a particular direction, and a dielectric layer is formed on the entire surface of the rear substrate while covering the address electrodes. Barrier ribs are formed in a stripe pattern on the dielectric layer such that each barrier rib is placed between adjacent address electrodes, and red (R), green (G), and blue (B) phosphor layers are formed between the neighboring barrier ribs.  
      Discharge sustain electrodes are formed on the surface of a front substrate facing the rear substrate in a direction crossing the direction of the address electrodes. The discharge sustain electrodes have a pair of transparent electrodes formed with indium tin oxide (ITO), and bus electrodes formed with a metallic material. A dielectric layer and an MgO protective layer are sequentially formed on the entire surface of the front substrate while covering the discharge sustain electrodes.  
      The address electrodes formed on the rear substrate and the discharge sustain electrodes formed on the front substrate cross each other, and the crossed regions thereof form discharge cells.  
      An address voltage is applied between the address electrodes and the discharge sustain electrodes so as to cause the address discharge, and a sustain voltage is applied between the pair of discharge sustain electrodes so as to cause the sustain discharge. At this point, vacuum ultraviolet rays are generated, and they excite the relevant phosphors to emit visible rays through the transparent front substrate, thereby displaying desired images.  
      With respect to the above-structured PDP, the bus electrodes are formed through photolithography. In the photolithography process, a photosensitive silver (Ag) paste is coated onto the entire surface of the rear substrate to a predetermined thickness, and is patterned through drying, light exposing, and developing steps; or a photosensitive silver (Ag) tape is attached to the entire surface of the rear substrate, and is patterned through light exposing and developing steps.  
      Particularly, the bus electrodes have a black and white double-layered structure to enhance contrast. For this purpose, a black paste and a white paste are sequentially coated onto the entire surface of the rear substrate, and are exposed to light at the same time. The black electrode layer based on the black paste is formed with a conductive material.  
      When the bus electrode is formed in the above manner, it involves a constant thickness. However, edge curls (with the firing of the electrode, the edges thereof becoming sharp) are liable to be formed at both lateral sides of the bus electrode. When a dielectric layer is formed on the bus electrode, the edge curls cause the dielectric formation material to be deposited at the lateral sides of the bus electrode, which generates bubble at those points. The incidental bubble generation structure is liable to deteriorate the voltage resistance of the bus electrode. Therefore, the discharge cells at the bus electrode area exhibit abnormalities in their discharge state.  
      Meanwhile, a black stripe is formed on the front substrate at the non-discharge area thereof to enhance the contrast. The black stripe may be formed together with the bus electrodes, or may be formed separately after the formation of the bus electrodes.  
      When the black stripe and the bus electrodes are formed together with the same material, the black stripe is electrically conductive as are the bus electrodes. Therefore, when the black stripe is formed in the entire non-discharge area, the neighboring discharge sustain electrodes for discharge cells positioned close to each other are likely to be short circuited. Furthermore, since the black stripe contains a conductive material, the density thereof becomes deteriorated, limiting contrast enhancement.  
      On the other hand, when the black stripe is separately formed after the formation of the bus electrodes, the printing, drying, light exposing, developing and firing steps for forming the black stripe must be repeated after the printing, drying, light exposing, developing and firing steps for forming the bus electrodes are performed. This involves complicated processing steps and much time consumption, and hence, it is not appropriate for the mass production process.  
     SUMMARY OF THE INVENTION  
      It is an object of the present invention to provide a method of manufacturing a PDP in which electrodes are formed using an offset printing technique to reduce electrode material consumption, and to form a fine and precise electrode pattern.  
      It is another object of the present invention to provide a method of manufacturing a PDP in which a nonconductive black layer is formed in a non-discharge area with the formation of bus electrodes on the front substrate using an offset printing technique to enhance the contrast in a simplified manner.  
      It is still another object of the present invention to provide a PDP with improved electrode structure and enhanced contrast.  
      In one embodiment of the present invention, the PDP includes a first substrate and a second substrate facing each other, and address electrodes formed in parallel on the second substrate. Barrier ribs are arranged between the first and second substrates to define a plurality of discharge cells, and a phosphor layer is formed within each respective discharge cell. The PDP further includes discharge sustain electrodes which have transparent electrodes formed on the first substrate in a direction crossing the address electrodes, and bus electrodes formed on the transparent electrodes while extending in a direction parallel to that of the transparent electrodes. A gap between adjacent transparent electrodes of the discharge cells positioned adjacent to each other in the direction of the address electrodes is filled with a nonconductive opaque-colored layer.  
      The bus electrode and the nonconductive opaque-colored layer are convex-shaped with a predetermined curvature in the direction of the thickness thereof.  
      The nonconductive opaque-colored layer partially overlaps with the transparent electrodes. The bus electrodes are positioned close to the nonconductive opaque-colored layer, and the nonconductive opaque-colored layer may partially overlap with the bus electrodes and the transparent electrodes. The bus electrodes are placed on the transparent electrodes and the nonconductive opaque-colored layer.  
      The bus electrode has a width-direction center placed on the transparent electrode while being electrically connected to the transparent electrode, and has a periphery placed on the nonconductive opaque-colored layer. The bus electrode has an oval-shaped cross section taken perpendicular to the longitudinal direction thereof.  
      The bus electrode may have one side portion around the width-direction center thereof formed on the transparent electrode, and an opposite side portion which overlaps with the periphery of the nonconductive opaque-colored layer sided with the transparent electrode.  
      The nonconductive opaque-colored layer may cover the bus electrodes.  
      The nonconductive opaque-colored layer is based on black, and the bus electrode is formed with an electrode material based on white.  
      With a method of manufacturing the PDP, a plurality of transparent electrodes with a predetermined pattern are formed on a first substrate such that the transparent electrodes proceed parallel to each other. A gravure groove having a predetermined pattern is filled with a nonconductive opaque-colored paste. The nonconductive opaque-colored paste is transferred from the gravure groove to a printing blanket. The nonconductive opaque-colored paste is transcribed from the printing blanket onto the first substrate such that the paste is targeted at the non-discharge region between the neighboring transparent electrodes. A gravure groove having a predetermined bus electrode pattern is filled with a bus electrode paste. The bus electrode paste is transferred from the gravure groove to the printing blanket. The bus electrode paste is transcribed from the printing blanket onto the transparent electrodes formed on the first substrate. The nonconductive opaque-colored paste pattern and the bus electrode paste pattern formed on the first substrate are dried and fired. A dielectric layer is formed on the first substrate such that the dielectric layer covers the transparent electrodes, the bus electrodes, and the nonconductive opaque-colored layer. A second substrate is aligned with the first substrate such that the first and second substrates face each other, and a discharge gas is injected between the first and second substrates. The substrates are then sealed with respect to each other.  
      The gap between adjacent transparent electrodes on the first substrate corresponding to the non-discharge region, is filled with the nonconductive opaque-colored paste. The coated nonconductive opaque-colored paste is overlapped with the periphery of the transparent electrodes.  
      The bus electrode paste is overlapped with the nonconductive opaque-colored paste. The bus electrode paste may completely cover the nonconductive opaque-colored paste.  
      The bus electrode paste may partially overlap the periphery of the nonconductive opaque-colored paste, and partially overlap the transparent electrodes.  
      The bus electrode paste may be formed on the transparent electrodes such that the bus electrode paste is positioned close to the periphery of the nonconductive opaque-colored paste that partially overlaps the transparent electrodes.  
      It is possible that the bus electrodes are formed on the transparent electrodes, and that the nonconductive opaque-colored paste covers the bus electrodes formed on the transparent electrodes.  
      The nonconductive opaque-colored paste is based on black, and the bus electrode paste is formed with an electrode material based on white.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:  
       FIG. 1  is a partial exploded perspective view of a PDP according to a first embodiment of the present invention;  
       FIG. 2  is a sectional view of the PDP of  FIG. 1  according to the first embodiment of the present invention, illustrating the structure thereof where discharge sustain electrodes and a black pattern are formed on a first substrate;  
       FIGS. 3A  to  3 E sequentially illustrate the electrode printing steps using an offset printing technique;  
       FIG. 4  schematically illustrates the process of forming a groove at a gravure plate, filling the groove with a paste, and transcribing it onto a glass substrate;  
       FIG. 5  schematically illustrates the process of forming a groove at a gravure roll, filling the groove with a paste, and transcribing it onto a glass substrate;  
       FIG. 6  is a sectional view of a PDP according to a second embodiment of the present invention, illustrating the structure thereof wherein discharge sustain electrodes and a black pattern are formed on a first substrate;  
       FIG. 7  is a sectional view of a PDP according to a third embodiment of the present invention, illustrating the structure thereof wherein discharge sustain electrodes and a black pattern are formed on a first substrate;  
       FIG. 8  is a sectional view of a PDP according to a fourth embodiment of the present invention, wherein discharge sustain electrodes and a black pattern are formed on a first substrate;  
       FIG. 9  is an exploded perspective view of an AC-type PDP; and  
       FIG. 10  illustrates the structure of the PDP where bus electrodes and a black stripe are formed on a front substrate through photolithography. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
      The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown.  
       FIG. 1  is a partial exploded perspective view of a PDP according to a first embodiment of the present invention, and  FIG. 2  is a sectional view of the PDP illustrating the structure thereof wherein discharge sustain electrodes and a black pattern are formed together on a first substrate.  
      As shown in the drawings, the PDP includes first and second substrates  10  and  20 , respectively, spaced apart from each other by a predetermined distance while facing each other, and barrier ribs  25  arranged between the first substrate  10  and the second substrate  20  to define a plurality of discharge cells  27  in which plasma discharge take place. Discharge sustain electrodes  12 ,  13  and  12 ′ are formed on the first substrate  10 , and address electrodes  21  are formed on the second substrate  20 . Red (R), blue (B), and green (G) phosphors are coated onto the inner surface of the discharge cells  27  to form phosphor layers  29 .  
      Specifically, a plurality of address electrodes  21  are formed on the surface of the second substrate  20  facing the first substrate  10  in a certain direction (the Y-axis direction of the drawing). The address electrodes  21  are spaced apart from each other by a predetermined distance while extending parallel to each other. A dielectric layer  23  is formed on the second substrate  20  while covering the address electrodes  21 .  
      A plurality of discharge sustain electrodes  12 ,  13  and  12 ′ are formed on the first substrate  10  in a direction crossing the address electrodes  21  (the X-axis direction in  FIG. 1 ) while extending parallel to each other, and the discharge cell wherein the pair of discharge sustain electrodes face each other forms a pixel. The pair of discharge sustain electrodes  12  and  13  function as an X electrode (common electrode) and a Y electrode (scan electrode), and the discharge sustain electrodes  12 ,  13  and  12 ′ further comprise transparent electrodes  12   a ,  13   a  and  12 ′ a , respectively, and bus electrodes  12   b ,  13   b  and  12 ′ b , respectively. The transparent electrodes  12   a ,  13   a , and  12 ′ a  may be formed with a stripe shape, or may be separately formed at the respective discharge cells  27  with a protrusion shape.  
      Meanwhile, bus electrodes  12   b ,  13   b , and  12 ′ b  are formed on the transparent electrodes  12   a ,  13   a  and  12 ′ a , respectively, while extending parallel thereto, and are biased from the widthwise center to one side portion thereof. In particular, with the area where a pair of transparent electrodes  12   a  and  13   a  correspondingly form a discharge cell, the bus electrodes  12   b  and  13   b  are arranged on the respective transparent electrodes  12   a  and  13   a  such that they are placed at the opposite side portions of the transparent electrodes, and distant from each other. The bus electrodes  12   b ,  13   b  and  12 ′ b  are formed with a silver (Ag) electrode material, and are white-colored. The bus electrodes compensate for the high resistance of the ITO electrode for the transparent electrodes  12   a ,  13   a  and  12 ′ a  so as to reduce the voltage drop on the discharge sustain electrodes.  
      A nonconductive black layer  15  is formed at the region between adjacent transparent electrodes  13   a  and  12 ′ a  placed within the different discharge cells adjacent to each other in the direction of the address electrodes (the Y-axis direction of the drawing), corresponding to the non-discharge area (referred to hereinafter simply as the ‘non-discharge region’). The nonconductive black layer  15  is overlapped with the transparent electrodes  12   a ,  13   a  and  12 ′ a . That is, the black layer  15  occupies all the non-discharge region, and is partially overlapped with the portion of the transparent electrodes beside the non-discharge region.  
      The bus electrodes  12   b ,  13   b  and  12 ′ b  are placed on the transparent electrodes  12   a ,  13   a  and  12 ′ a  as well as on the non-conductive black layer  15 . That is, the width-direction center of the bus electrodes is placed on the transparent electrodes  12   a ,  13   a  and  12 ′ a  while being electrically connected thereto, and the periphery thereof is on the nonconductive black layer  15 . For this purpose, the bus electrodes  12   b ,  13   b  and  12 ′ b  have an oval-shaped cross section which is taken perpendicular to the longitudinal direction thereof. The bus electrodes may be formed using an offset printing technique.  
      As the nonconductive black layer  15  is formed with a nonconductive material to enhance the contrast, it involves sufficient intensity of opaqueness. Accordingly, the black layer  15  can be formed in the entire non-discharge region without incurring a short circuit between the neighboring discharge sustain electrodes, thereby exerting a reliable contrast enhancement effect.  
      A method of forming electrodes on a substrate for the PDP using an offset printing technique will be now explained with reference to FIGS.  3  to  5 .  
       FIGS. 3A  to  3 E sequentially illustrate the electrode printing steps using an offset printing technique.  
      As shown in  FIG. 3A , a groove is formed in a plate  31  with a target electrode pattern, and is filled with an electrode paste  34 . Note that the electrode paste  34 , which overflows on the grooved plate  31 , is removed using a blade  32 .  
      Thereafter, as shown in  FIGS. 3B and 3C , the electrode paste  34  filled within the groove of the grooved plate  31  is transferred to a printing blanket  35 . As shown in  FIGS. 3D and 3E , the electrode paste  34  is then transcribed from the printing blanket  35  onto a glass substrate  37 , followed by drying and firing it.  
       FIG. 4  illustrates the process of forming a groove in a gravure plate, filling the groove with a paste, and transcribing the paste onto a glass substrate, and  FIG. 5  illustrates the process of forming a groove in a gravure roll, filling the groove with a paste, and transcribing the paste onto a glass substrate.  
      A bus electrode pattern and a nonconductive black layer pattern are formed by making a groove in a gravure plate  31  or in a gravure roll  39 , filling it with a paste, transferring the paste to a blanket  35 , and transcribing it onto a glass substrate  37 .  
      The offset printing technique for forming bus electrodes and a nonconductive black layer on a substrate for the PDP will be now explained more specifically.  
      First, referring to  FIG. 2 , a plurality of transparent electrodes  12   a ,  13   a  and  12 ′ a  with a predetermined pattern are formed on the first substrate  10  in such a manner that they extend in parallel with each other.  
      Thereafter, the gravure groove with a predetermined pattern is filled with a nonconductive black paste. The pattern of the gravure groove is formed based on the shape of the previously formed transparent electrodes  12   a ,  13   a  and  12 ′ a  such that the target layer covers the non-discharge region while partially overlapping portions of the transparent electrodes  12   a ,  13   a  and  12 ′ a . The gravure groove may be selectively formed in a gravure plate  31  ( FIG. 4 ) or a gravure roll  39  ( FIG. 5 ). After the filling of the groove with paste, overflowing paste is removed using a blade  32  ( FIG. 3A ).  
      The nonconductive black paste filled within the gravure groove is transferred to a printing blanket  35  ( FIGS. 3B and 3C ).  
      The nonconductive black paste is then transcribed from the printing blanket  35  onto the first substrate  10  ( FIG. 2 ). At this point, the nonconductive black paste is targeted at the non-discharge region on the first substrate  10  while partially overlapping the transparent electrodes  12   a ,  13   a  and  12 ′ a.    
      After the coating of the nonconductive black paste, a bus electrode paste is coated onto the substrate  10 . The method of coating the bus electrode paste is similar to that of coating the nonconductive black paste.  
      That is, the gravure groove with a predetermined bus electrode pattern is filled with a bus electrode paste. At this time, in view of the shape of the previously formed transparent electrodes  12   a ,  13   a  and  12 ′ a , and the nonconductive black layer  15 , the bus electrodes  12   b ,  13   b  and  12 ′ b  are formed on the transparent electrodes  12   a ,  13   a  and  12 ′ a  so as to extend parallel thereto.  
      Specifically, in order to form the bus electrodes  12   b ,  13   b  and  12 ′ b , it is preferable that the bus electrode paste completely cover the nonconductive black paste coated on the first substrate  10 . As the nonconductive black paste has some fluidity before drying, it is extruded to the side portions around the center (widthwise) of the bus electrode so that the bus electrode paste directly contacts the transparent electrode while being electrically connected thereto.  
      The bus electrode paste within the gravure groove is transferred to a printing blanket  35  ( FIGS. 3B and 3C ), and is then transcribed from the printing blanket  35  onto the first substrate  10  ( FIG. 2 ).  
      The nonconductive black paste pattern and the bus electrode paste pattern are then dried and fired. A dielectric layer is formed on the first substrate  10  such that it covers the transparent electrodes  12   a ,  13   a  and  12 ′ a , the bus electrodes, and the nonconductive black layer  15 , and a protective layer is formed on the dielectric layer, thereby completing the front substrate for the PDP. When the bus electrodes and the nonconductive black layer  15  are formed using an offset printing technique, the contrast-enhancement black layer and the bus electrodes  12   b ,  13   b  and  12 ′ b  can be formed in a simplified manner. Since it is not required that a part of the bus electrode be formed as a black electrode, excellent electrical conductivity can be maintained. At this point in the process, the bus electrode or the nonconductive black layer  15  is convex-shaped with a predetermined curvature in the direction of the thickness thereof.  
      The front substrate is aligned to a rear substrate, made through a separate process, such that they face each other, and a discharge gas is injected between the substrates. The substrates are then sealed to each other, thereby completing the PDP.  
      The nonconductive paste used in forming the nonconductive black layer  15  is not limited to a black-colored one paste. Rather, other nonconductive opaque-colored pastes that are well adapted for a contrast enhancement purpose may be used. Furthermore, a white electrode material, such as silver (Ag), can be used as the bus electrode paste for forming the bus electrodes, but a different colored material may be used for that purpose provided that it has reasonable electrical conductivity.  
      PDPs according to the second to fourth embodiments of the present invention will be now explained in detail. With these PDPs, the bus electrodes  12   b ,  13   b  and  12 ′ b  and the nonconductive black layer  15  may be formed using the offset printing technique.  
       FIG. 6  is a sectional view of a PDP according to the second embodiment of the present invention, and illustrates the structure thereof wherein discharge sustain electrodes and a black pattern are formed together on the first substrate.  
      As shown in  FIG. 6 , a nonconductive black layer  45  occupies the entire non-discharge region while partially overlapping with the transparent electrodes  42   a ,  43   a  and  42 ′ a . That is, the black layer  45  covers the non-discharge region while partially overlapping with the portions of the transparent electrodes  42   a ,  43   a  and  42 ′ a  beside the non-discharge region.  
      The bus electrodes  42   b ,  43   b , and  42 ′ b  are placed on the transparent electrodes  42   a ,  43   a  and  42 ′ a  as well as on the nonconductive black layer  45 , as in the structure related to the first embodiment of the invention. However, in this embodiment, one side of the bus electrodes  42   b ,  43   b , and  42 ′ b  are placed on the transparent electrodes  42   a ,  43   a  and  42 ′ a  while being electrically connected thereto, and the other side of the bus electrodes  42   b ,  43   b  and  42 ′ b  are overlapped with the periphery of the nonconductive black layer  45  that partially overlaps the transparent electrodes  42   a ,  43   a  and  42 ′ a.    
       FIG. 7  is a sectional view of a PDP according to a third embodiment of the present invention, and illustrates the structure thereof where discharge sustain electrodes and a black pattern are formed together on the first substrate.  
      As shown in  FIG. 7 , a nonconductive black layer  55  occupies the entire non-discharge region while partially overlapping the transparent electrodes  52   a ,  53   a  and  52 ′ a . That is, the black layer  55  covers the non-discharge region and partially overlaps portions of the transparent electrodes beside  52   a ,  53   a  and  52 ′ a  the non-discharge region.  
      The bus electrodes  52   b ,  53   b  and  52 ′ b  are placed on the transparent electrodes  52   a ,  53   a , and  52 ′ a  while extending parallel thereto, and are positioned close to the nonconductive black layer  55  that partially overlaps the transparent electrodes  52   a ,  53   a  and  52 ′ a.    
       FIG. 8  is a sectional view of a PDP according to a fourth embodiment of the present invention, and illustrates the structure thereof where discharge sustain electrodes and a black pattern are formed together on the first substrate.  
      As shown in  FIG. 8 , a nonconductive black layer  65  occupies the entire non-discharge region while partially overlapping the transparent electrodes  62   a ,  63   a  and  62 ′ a . In this embodiment, the nonconductive black layer  65  covers the bus electrodes  62   b ,  63   b  and  62 ′ b.    
      For this purpose, a bus electrode paste is first coated onto the transparent electrodes  62   a ,  63   a  and  62 ′ a , and a nonconductive black paste is coated thereon.  
       FIG. 9  is an exploded perspective view of an AC-type PDP, while  FIG. 10  illustrates the structure of the PDP wherein bus electrodes and a black stripe are formed on a front substrate through photolithography.  
      As shown in  FIG. 9 , in the AC PDP, address electrodes  112  are formed on a rear substrate  110  in a particular direction (in the X-axis direction in  FIG. 9 ), and a dielectric layer  113  is formed on the entire surface of the rear substrate  110  while covering the address electrodes  112 . Barrier ribs  115  are formed in a stripe pattern on the dielectric layer  113  such that each barrier rib  115  is positioned between adjacent address electrodes  112 , and red (R), green (G), and blue (B) phosphor layers  117  are formed between the adjacent barrier ribs  115 .  
      Discharge sustain electrodes  102  and  103  are formed on the surface of a front substrate  100  facing the rear substrate  110  in a direction crossing the address electrodes  112  (the Y-axis direction in  FIG. 9 ). The discharge sustain electrodes  102  and  103  have a pair of transparent electrodes  102   a  and  103   a , respectively, formed with indium tin oxide (ITO), and bus electrodes  102   b  and  103   b , respectively, formed with a metallic material. A dielectric layer  106  and an MgO protective layer  108  are sequentially formed on the entire surface of the front substrate  100  while covering the discharge sustain electrodes  102  and  103 .  
      The address electrodes  112  formed on the rear substrate  110  and the discharge sustain electrodes  102  and  103  formed on the front substrate  100  cross each other, and the crossed regions thereof form discharge cells.  
      An address voltage Va is applied between the address electrodes  112  and the discharge sustain electrodes  102  and  103  so as to cause the address discharge, and sustain voltage Vs is applied between the pair of discharge sustain electrodes  102  and  103  so as to cause the sustain discharge. At this point, vacuum ultraviolet rays are generated, and they excite the relevant phosphors to emit visible rays through the transparent front substrate  100 , thereby displaying desired images.  
      With the above-structured PDP, the bus electrodes  102   b  and  103   b  are formed through photolithography. In the photolithography process, a photosensitive silver (Ag) paste is coated onto the entire surface of the rear substrate  110  to a predetermined thickness, and is patterned through drying, light exposing and developing steps; or a photosensitive silver (Ag) tape is attached to the entire surface of the rear substrate  110 , and is patterned through light exposing and developing steps.  
      Particularly, the bus electrodes  102   b  and  103   b  have a black and white double-layered structure to enhance contrast. For this purpose, a black paste and a white paste are sequentially coated onto the entire surface of the rear substrate  110 , and are exposed to light at the same time. The black electrode layer based on the black paste is formed with a conductive material.  
      When the bus electrodes  102   b  and  103   b  are formed in the above way, it involves a constant thickness. However, as shown in  FIG. 10 , edge curls (with the firing of the electrode, the edges thereof become sharp) are liable to be formed at both lateral sides of the bus electrodes  102   b  and  103   b . When a dielectric layer is formed on the bus electrodes  102   b  and  103   b , the edge curls cause the dielectric formation material to be deposited on the lateral sides of the bus electrodes, which generates a bubble at those points. The incidental bubble generation structure is liable to cause the voltage resistance of the bus electrodes to deteriorate. Therefore, the discharge cells at the bus electrode areas exhibit abnormalities in their discharge state.  
      Meanwhile, as shown in  FIG. 10 , a black stripe  120  is formed in the non-discharge area of the front substrate  100  so as to enhance the contrast. The black stripe  120  may be formed together with the bus electrodes  102  and  103 , or separately after the formation of the bus electrodes  102  and  103 .  
      When the black stripe  120  and the bus electrodes  102  and  103  are formed together with the same material, the black stripe  120  is electrically conductive as are the bus electrodes  102  and  103 . Therefore, when the black stripe  120  is formed in the entire non-discharge area, the adjacent discharge sustain electrodes for the discharge cells positioned close to each other are liable to be short circuited. Furthermore, since the black stripe  120  contains a conductive material, the density thereof becomes deteriorated, limiting contrast enhancement.  
      As described above, with the inventive method of manufacturing a PDP, the contrast enhancement black layer and the bus electrodes are formed in a simplified manner, and it is not necessary to partially form the bus electrode with a black electrode, thereby maintaining extremely good electrical conductivity.  
      Furthermore, with the inventive PDP, a nonconductive material is used to enhance the contrast, thereby obtaining sufficient intensity, and a black layer is formed in the entire non-discharge region without incurring a short circuit between the adjacent discharge sustain electrodes, thereby producing a reliable contrast enhancement.  
      Although preferred embodiments of the present invention have been described in detail above, it should be clearly understood that many variations and/or modifications of the basic inventive concept taught herein will appear to those skilled in the art but will still fall within the spirit and scope of the present invention, as defined in the appended claims.