Abstract:
Disclosed is a plasma display panel comprises a lower substrate and an upper substrate, spaced apart by a predetermined distance to define a discharge space therebetween; a plurality of barrier ribs between the lower substrate and the upper substrate, partitioning the discharge space to form a plurality of discharge cells; a plurality of address electrodes formed in parallel on the upper surface of the lower substrate; a plurality of discharge electrodes formed at an angle to the address electrodes on the lower surface of the upper substrate; a fluorescent layer formed on the inner walls of the discharge cells; and an external light shielding member formed on the upper substrate, preventing external light from entering the discharge cells, wherein the lower surface of the upper substrate has a plurality of cylindrical lenses, corresponding to each of the discharge cells.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 10-2004-0024510, filed in the Korean Intellectual Property Office on Apr. 9, 2004, the entire disclosure of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a plasma display panel. More particularly, the present invention relates to a plasma display panel with an improved structure that can enhance brightness, and can enhance contrast, for example, when a plasma display panel is operated in a brightly lit room. 
     2. Description of the Related Art 
     A plasma display panel (PDP) is an apparatus to form an image using an electrical discharge. Its superior performance in terms of brightness and viewing angle has ensured its popularity. In such a PDP, a DC or AC voltage applied to electrodes causes a gas discharge between the electrodes, and ultraviolet rays generated by the discharge excite a fluorescent material, which emits a visible light. 
     PDPs are classified as either a DC type or an AC type, according to the type of discharge. The DC type PDP has a structure in which all electrodes are exposed to a discharge space, and charges move directly between the electrodes. The AC type PDP has a structure in which at least one electrode is covered with a dielectric layer, and charges do not move directly between the corresponding electrodes but discharge is performed by wall charges. 
     Also, PDPs may be classified as a facing discharge type or a surface discharge type, according to the arrangement of the electrodes. The facing discharge type PDP has a structure in which a pair of sustain electrodes are formed respectively on an upper substrate and a lower substrate, and discharge occurs perpendicular to the substrate. The surface discharge type PDP has a structure in which a pair of sustain electrodes are formed on the same substrate, and discharge occurs parallel to the substrate. 
     The facing discharge type PDP has a high luminous efficiency, but a disadvantage being that the fluorescent layer is easily deteriorated. For this reason, the surface discharge type PDP is presently more common. 
       FIGS. 1 and 2  show the construction of a conventional surface discharge type PDP. In  FIG. 2 , the upper substrate  20  is shown rotated by 90 degrees for easier understanding of the inner structure of the PDP. 
     Referring to  FIGS. 1 and 2 , the conventional PDP includes a lower substrate  10  and an upper substrate  20  facing each other. 
     On the upper surface of the lower substrate  10 , a plurality of address electrodes  11  are arranged in a stripe configuration. The address electrodes  11  are covered by a first dielectric layer  12  (preferably white). On the first dielectric layer  12 , a plurality of barrier ribs  13  are formed at a predetermined spacing to prevent electrical and optical cross-talk between discharge cells  14 . On the inner surfaces of the discharge cells  14 , which are partitioned by the barrier ribs  13 , a red (R), green (G) and blue (B) fluorescent layer  15  is coated to a predetermined thickness. The discharge cells  14  are filled with a discharge gas, which is typically a mixture of neon (Ne) and a small amount of xenon (Xe), as is generally used for plasma discharge. 
     The upper substrate  20  is a transparent substrate, which transmits visible light, and is preferably made of glass. The upper substrate  20  is coupled to the lower substrate  10  having the barrier ribs  13 . On the lower surface of the upper substrate  20 , sustaining electrodes  21   a  and  21   b  are formed in pairs and are perpendicular to the address electrodes  11  and are arranged in a stripe configuration. The sustaining electrodes  21   a  and  21   b  are formed of a transparent conductive material, such as indium tin oxide (ITO), to transmit visible light. In order to reduce the line resistance of the sustaining electrodes  21   a  and  21   b , bus electrodes  22   a  and  22   b  are formed of a metal, on the lower surface of the respective sustaining electrodes  21   a  and  21   b , to a width less than that of the sustaining electrodes  21   a  and  21   b . These sustaining electrodes  21   a  and  21   b  and the bus electrodes  22   a  and  22   b  are covered with a transparent second dielectric layer  23 . On the lower surface of the second dielectric layer  23 , a protective layer  24  is formed. The protective layer  24  prevents the second dielectric layer  23  from damage by plasma sputtering, and emits secondary electrons, thereby lowering discharge voltages. The protective layer  24  is generally formed of magnesium oxide (MgO). A plurality of black stripes  30  are formed at a predetermined spacing, parallel to the sustaining electrodes  21   a  and  21   b , on the upper surface of the upper substrate  20 , to prevent external light from entering the panel. 
     The conventional PDP constructed as above generally uses a cycle of two operations: address discharge and sustaining discharge. The address discharge occurs between the address electrode  11  and any one of the sustaining electrodes  21   a  and  21   b , and during the address discharge, wall charges are formed. The sustaining discharge is caused by a potential difference between the sustaining electrodes  21   a  and  21   b  positioned at the discharge cells  14  in which the wall charges are formed. During the sustaining discharge, the florescent layer  15  of the corresponding discharge cell is excited by ultraviolet rays generated from the discharge gas, emitting visible lights. The visible light emitted through the upper substrate  20  form the image. 
     However, when the conventional PDP constructed as above is used in brightly lit room conditions, external light enters the discharge cells  14 , mixing with the light generated by the discharge cells  14 . This lowers the contrast and reduces the image display performance of the PDP when used in a brightly lit room. 
     SUMMARY OF THE INVENTION 
     The present invention provides a PDP with better brightness, and better contrast in a brightly lit room, by improving the structure of an upper substrate. 
     According to an aspect of the present invention, there is provided a plasma display panel, comprising a lower substrate and an upper substrate, spaced apart from each other by a predetermined distance to define a discharge space therebetween; a plurality of barrier ribs between the lower substrate and the upper substrate, partitioning the discharge space to form a plurality of discharge cells; a plurality of address electrodes are formed in parallel on the upper surface of the lower substrate; a plurality of discharge electrodes are formed at an angle to the address electrodes on the lower surface of the upper substrate; a fluorescent layer is formed on the inner walls of the discharge cells; and an external light shielding member is formed on the upper substrate to prevent external light from entering the discharge cells, wherein the lower surface of the upper substrate has a plurality of cylindrical lenses, which correspond to each of the discharge cells, to focus visible lights generated by discharge and emit the visible light out of the PDP. 
     It is preferable that the cylindrical lenses are formed integral with the upper substrate. The cylindrical lenses may be formed parallel to the address electrodes. At this point, the external light shielding member may comprise a plurality of stripes (preferably black) that are formed parallel to the address electrodes on the upper surface of the upper substrate. It is preferable that the stripes are formed in locations where no visible light is emitted by the discharge cells. The stripes may comprise a conductive film for shielding electromagnetic interference (EMI). It is preferable that the upper surface of the upper substrate between the stripes be treated with a non-glare material. 
     Alternatively, the cylindrical lenses may be formed perpendicular to the address electrodes. At this point, the external light shielding member may comprise a plurality of black stripes formed perpendicular to the address electrodes on the upper surface of the upper substrate. The discharge electrodes may be formed on the lower surfaces of the cylindrical lenses. 
     A transparent material layer may be formed to cover the lower surfaces of the cylindrical lenses. The discharge electrodes may be formed on the lower surface of the transparent material layer. 
     The barrier ribs may be formed parallel to the address electrodes, and bus electrodes may be formed on the lower surfaces of the discharge electrodes. 
     Also, a first dielectric layer covering the address electrodes may be formed on the upper surface of the lower substrate, and a second dielectric layer covering the discharge electrodes may be formed on the lower surface of the upper substrate. Further, a protective layer may be formed on the lower surface of the second dielectric layer. 
     According to another aspect of the present invention, there is provided a plasma display panel comprising a lower substrate and an upper substrate, spaced apart from each other by a predetermined distance to define a discharge space therebetween; a plurality of barrier ribs are arranged between the lower substrate and the upper substrate, thereby partitioning the discharge space to form a plurality of discharge cells; a plurality of address electrodes are formed in parallel on the upper surface of the lower substrate; a plurality of discharge electrodes are formed at an angle to the address electrodes on the lower surface of the upper substrate; a fluorescent layer is formed on the inner walls of the discharge cells; and an external light shielding member is formed on the upper substrate to prevent external light from entering the discharge cells, wherein the lower surface of the upper substrate has cylindrical lenses, each of which is formed corresponding to two or more discharge cells, to focus visible light generated by a discharge and emit the visible light from the discharge out of the PDP. 
     It is also preferable that each of the cylindrical lenses corresponds to three discharge cells forming one pixel. Additionally, it is preferable that the cylindrical lenses are parallel to the address electrodes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
         FIG. 1  is a cutaway perspective view of a conventional surface discharge type PDP; 
         FIG. 2  is a cross-sectional view illustrating the inner structure of the PDP of  FIG. 1 ; 
         FIG. 3  is a cutaway perspective view of a PDP according to an embodiment of the present invention; 
         FIG. 4  is a cross-sectional view illustrating the inner structure of the PDP of  FIG. 3 ; 
         FIG. 5  is a cross-sectional view illustrating a modification of the PDP of  FIG. 3 ; 
         FIG. 6  is a cutaway perspective view of a PDP according to another embodiment of the present invention; 
         FIG. 7  is a cross-sectional view illustrating the inner structure of the PDP of  FIG. 6 ; 
         FIG. 8  is a cross-sectional view illustrating a modification of the PDP of  FIG. 6 ; 
         FIG. 9  is a cutaway perspective view of a PDP according to a further embodiment of the present invention; 
         FIG. 10  is a cross-sectional view illustrating the inner structure of the PDP of  FIG. 9 ; and 
         FIG. 11  is a cross-sectional view illustrating a modification of the PDP of  FIG. 9 . 
     
    
    
     In the drawings, it should be understood that like reference numbers refer to similar features, structures, and elements. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Embodiments of the present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. 
       FIG. 3  is a cutaway perspective view of a PDP according to an embodiment of the present invention, and  FIG. 4  is a cross-sectional view illustrating the inner structure of the PDP of  FIG. 3 . 
     Referring to  FIGS. 3 and 4 , the PDP comprises a lower substrate  110  and an upper substrate  120 , facing each other at a predetermined spacing. This space between the lower substrate  110  and the upper substrate  120  corresponds to a discharge space where plasma discharge occurs. 
     The lower substrate  110  is preferably formed of glass. A plurality of address electrodes  111  are formed in parallel with one another in a stripe configuration on the upper surface of the lower substrate  110 . A first dielectric layer  112  is formed on the address electrodes  111  to cover the address electrodes  111  and the lower substrate  110 . The first dielectric layer  112  can be formed by coating a dielectric material (preferably white) to a predetermined thickness. 
     A plurality of barrier ribs  113  are formed in parallel at a predetermined spacing, on the upper surface of the first dielectric layer  112 . The barrier ribs  113  partition the discharge space between the lower substrate  110  and the upper substrate  120 , thereby defining discharge cells  114 . The barrier ribs  113  prevent electrical and optical cross-talk between adjacent discharge cells  114 , thereby enhancing color purity. A red (R), green (G) and blue (B) fluorescent layer  115  is formed to a predetermined thickness on the upper surface of the first dielectric layer  112  and the sides of the barrier ribs  113  forming the inner walls of the discharge cells  114 . The fluorescent layer  115  is excited by ultraviolet rays generated by the plasma discharge, thereby emitting visible light of a certain color. The discharge cells  114  are preferably filled with a discharge gas, which is a mixture of neon (Ne) and a small amount of xenon (Xe), as is generally used for plasma discharge. 
     The upper substrate  120  is transparent to visible light, and is preferably formed of glass. A plurality of cylindrical lenses  120   a ,  120   b  and  120   c  are formed on the lower surface of the upper substrate  120 . The cylindrical lenses  120   a ,  120   b  and  120   c  correspond to each of the discharge cells  114 , and are formed parallel to the address electrodes  111 . It is preferable that the cylindrical lenses  120   a ,  120   b  and  120   c  are formed integral with the upper substrate  120 , which can be achieved by processing the lower surface of the upper substrate  120 . As shown in  FIG. 4 , the cylindrical lenses  120   a ,  120   b  and  120   c  focus the visible light generated in the discharge cells  114  and emit the visible light out of the PDP. Thus, the plurality of cylindrical lenses  120   a ,  120   b  and  120   c  corresponding to each of the discharge cells  114  to reduce the loss of visible light generated in the discharge cells  114  and at the same time enhance light integrity, thereby further enhancing the brightness of the PDP. 
     Although the present embodiment shows three cylindrical lenses  120   a ,  120   b  and  120   c  corresponding to each of the discharge cells  114 , the number of cylindrical lenses corresponding to each of the discharge cells  114  may be changed to two or four or more. 
     On the lower surfaces of the cylindrical lenses  120   a ,  120   b  and  120   c , discharge electrodes  121   a  and  121   b  for sustaining a discharge are formed in a pair for each discharge cell. The first and second discharge electrodes  121   a  and  121   b  are formed perpendicular to the address electrodes  111 . The first and second discharge electrodes  121   a  and  121   b  are preferably formed of a transparent conductive material, such as indium tin oxide (ITO), in order to transmit the visible light generated in the discharge cells  114 . On the lower surface of the first and second discharge electrodes  121   a  and  121   b , first and second bus electrodes  122   a  and  122   b , which are preferably made of metal, are formed. The first and second bus electrodes  122   a  and  122   b  are electrodes to decrease line resistance of the first and second discharge electrodes  121   a  and  121   b , and are preferably narrower than the first and second discharge electrodes  121   a  and  121   b.    
     On the lower surface of the cylindrical lenses  120   a ,  120   b  and  120   c  is formed a second dielectric layer  123  covering the first and second discharge electrodes  121   a  and  121   b  and the first and second bus electrodes  122   a  and  122   b . The second dielectric layer  123  can be formed by coating a preferably transparent dielectric material on the lower surface of the upper substrate  120  to a predetermined thickness. 
     A protective layer  124  is formed on the lower surface of the second dielectric layer  123 . The protective layer  124  prevents the second dielectric layer  123  and the first and second discharge electrodes  121   a  and  121   b  from being damaged by plasma sputtering and emits secondary electrons, thereby lowering discharge voltage. The protective layer  124  can preferably be formed by coating magnesium oxide (MgO) on the lower surface of the second dielectric layer  123  to a predetermined thickness. 
     An external light shielding member is provided on the upper surface of the upper substrate  120  to prevent external light from entering the discharge cells  114  through the upper substrate  120 . The external light shielding member is preferably formed of a plurality of parallel stripes  130  (preferably black) on the upper surface of the upper substrate  120  at a predetermined spacing. The stripes  130  are preferably of a uniform width and are parallel with the address electrodes  111  and the cylindrical lenses  120   a ,  120   b  and  120   c . The stripes  130  are formed where no visible light is emitted by the discharge cells  114 . Thus, when the stripes  130  are formed on the upper surface of the upper substrate  120 , the visible light generated by the discharge cells  114  is focused into the upper surface  140  of the upper substrate  120  as shown in  FIG. 4 , and is then diffused and emitted out of the PDP. Hence, since the stripes  130  can cover more of the upper surface of the upper substrate  120  than in the conventional PDP, external light can be more effectively prevented from entering the discharge cells  114 . As a result, contrast of the PDP when used in, for example, brightly lit room conditions, may be enhanced. The stripes  130  may include a conductive film for shielding electromagnetic interference (EMI). 
     Non-glare treatments are applied to portions of the upper surface  140  of the upper substrate  120  between the black stripes  130  to prevent external light from being reflected by the upper substrate  120 . 
     In the PDP constructed as above, when an address discharge occurs between the address electrode  111  and any one of the sustaining electrodes  121   a  and  121   b , wall charges are formed. Thereafter, when an AC voltage is applied to the first and second discharge electrodes  121   a  and  121   b , a sustaining discharge occurs inside the discharge cells  114  where the wall charges are formed. The sustaining discharge causes the discharge gases to generate ultraviolet rays, which excite the fluorescent layer  115  to generate visible light. 
     The visible light generated in the discharge cells  114  is focused onto the non-glare treated regions of the upper surface  140  of the upper substrate  120  by cylindrical lenses  120   a ,  120   b  and  120   c , and are then diffused and emitted out of the PDP. Thus, the loss of visible light generated in discharge cells  114  can be reduced and light integrity can be enhanced. 
     Moreover, the area covered by the stripes  130  formed on the upper surface of the upper substrate  120  can be higher than in the conventional PDP, further enhancing the contrast of the PDP when used in, for example, brightly lit room conditions. 
       FIG. 5  is a cross-sectional view illustrating another embodiment of the PDP of  FIG. 3 . Referring to  FIG. 5 , a transparent material layer  150  is formed to cover the lower surfaces of the cylindrical lenses  120   a ,  120   b  and  120   c . First and second discharge electrodes  121   a  and  121   b  are formed on the flat lower surface of the transparent material layer  150 . First and second bus electrodes  122   a  and  122   b  are formed on the lower surfaces of the first and second discharge electrodes  121   a  and  121   b . Also, a second dielectric layer  123  covering the first and second discharge electrodes  121   a  and  121   b  and the first and second bus electrodes  122   a  and  122   b  is formed on the lower surface of the preferably transparent material layer  150 . Thus, the transparent material layer  150  aids the formation of the first and second discharge electrodes  121   a  and  121   b  and the first and second bus electrodes  122   a  and  122   b.    
       FIG. 6  is a cutaway perspective view of a PDP according to another embodiment of the present invention, and  FIG. 7  is a cross-sectional view illustrating the inner structure of the PDP of  FIG. 6 . 
     Referring to  FIGS. 6 and 7 , the PDP comprises a lower substrate  210  and an upper substrate  220  that are spaced apart from each other by a predetermined distance. A discharge space is formed between the lower substrate  210  and the upper substrate  220 . 
     On the lower substrate  210 , a plurality of address electrodes  211  and a first dielectric layer  212  are preferably sequentially formed. 
     A plurality of barrier ribs  213  are formed parallel to the address electrodes  211 , at a predetermined spacing, on the first dielectric layer  212 . The barrier ribs  213  partition the discharge space between the lower substrate  210  and the upper substrate  220 , thereby defining discharge cells  214 . A fluorescent layer  215  is formed on the upper surface of the first dielectric layer  212 , and the side surfaces of the barrier ribs  213  forming inner walls of the discharge cells  214 . The discharge cells  214  are preferably filled with a discharge gas. 
     A plurality of cylindrical lenses  220   a ,  220   b  and  220   c  are formed on the lower surface of the upper substrate  220 . The cylindrical lenses  220   a ,  220   b  and  220   c  correspond to each of the discharge cells  214 , and are formed perpendicular to the address electrodes  211 . It is preferable that the cylindrical lenses  220   a ,  220   b  and  220   c  are formed integral with the upper substrate  220 , which can be performed by processing the lower surface of the upper substrate  220 . As shown in  FIG. 7 , the cylindrical lenses  220   a ,  220   b  and  220   c  focus the visible lights generated in the discharge cells  214  and emit visible light out of the PDP. Although the present embodiment shows three cylindrical lenses  220   a ,  220   b  and  220   c  corresponding to each of the discharge cells  214 , the number of cylindrical lenses corresponding to each of the discharge cells  214  may be changed to two or four or more. 
     On the lower surfaces of the cylindrical lenses  220   a ,  220   b  and  220   c , first and second discharge electrodes  221   a  and  221   b  for sustaining a discharge are formed in a pair for each discharge cell  214  and are formed perpendicular to the address electrodes  211 . On the lower surface of the first and second discharge electrodes  221   a  and  221   b , first and second bus electrodes  222   a  and  222   b , which are preferably made of metal, are formed. 
     A second dielectric layer  223  is preferably formed on the lower surface of the cylindrical lenses  220   a ,  220   b  and  220   c , to cover the first and second discharge electrodes  221   a  and  221   b  and the first and second bus electrodes  222   a  and  222   b . A protective layer  224  is formed on the lower surface of the second dielectric layer  223 . 
     An external light shielding member is provided on the upper surface of the upper substrate  220  to prevent external light from entering the discharge cells  214  through the upper substrate  220 . The external light shielding member is preferably formed of a plurality of parallel stripes  230  (preferably black) on the upper surface of the upper substrate  220  at a predetermined spacing. The stripes  230  are of constant width and are parallel with the cylindrical electrodes  220   a ,  220   b  and  220   c . The stripes  230  are formed where no visible light is emitted by the discharge cells  214 . Non-glare treatments are applied to portions of the upper surface  240  of the upper substrate  220  between the stripes  230 . The stripes  230  may include a conductive film for shielding electromagnetic interference (EMI). 
       FIG. 8  is a cross-sectional view illustrating a modification of the PDP of  FIG. 6 . Referring to  FIG. 8 , a transparent material layer  250  is formed to cover the lower surfaces of the cylindrical lenses  220   a ,  220   b  and  220   c . First and second discharge electrodes  221   a  and  221   b  are preferably formed on the flat lower surface of the transparent material layer  250 . First and second bus electrodes  222   a  and  222   b  are formed on the lower surfaces of the first and second discharge electrodes  221   a  and  221   b . Also, a second dielectric layer  223  is formed on the lower surface of the transparent material layer  250  to cover the first and second discharge electrodes  221   a  and  221   b  and the first and second bus electrodes  222   a  and  222   b . The transparent material layer  250  aids in forming the first and second discharge electrodes  221   a  and  221   b  and the first and second bus electrodes  222   a  and  222   b.    
       FIG. 9  is a cutaway perspective view of a PDP according to a further embodiment of the present invention, and  FIG. 10  is cross-a sectional view illustrating the inner structure of the PDP of  FIG. 9 . 
     Referring to  FIGS. 9 and 10 , the PDP comprises a lower substrate  310  and an upper substrate  320 , spaced apart from each other by a predetermined distance. A discharge space is formed between the lower substrate  310  and the upper substrate  320 . On the lower substrate  310 , a plurality of address electrodes  311  and a first dielectric layer  312  are formed, preferably sequentially. A plurality of barrier ribs  313  are preferably formed parallel to the address electrodes  311  at a predetermined spacing on the first dielectric layer  312 . The barrier ribs  313  partition the discharge space between the lower substrate  310  and the upper substrate  320 , thereby defining discharge cells  314 . 
     Red (R), green (G) and blue (B) fluorescent layers  315 R,  315 G and  315 B are sequentially formed on the upper surface of the first dielectric layer  312 , and side surfaces of the barrier ribs  313  forming the inner walls of the discharge cells  314 . The discharge cells  314  are preferably filled with a discharge gas, which is a mixture of neon (Ne) and a small amount of xenon (Xe), as is generally used for plasma discharge. 
     A plurality of cylindrical lenses  320   a  are formed on the lower surface of the upper substrate  320 . Each of the cylindrical lenses  320   a  corresponds to a plurality of the respective discharge cells  314 . Preferably, each of the cylindrical lenses  320   a  corresponds to one pixel of the PDP as shown in  FIGS. 9 and 10 . In other words, each of the cylindrical lenses  320   a  corresponds to three discharge cells  314  in which the red (R), green (G) and blue (B) fluorescent layers  315 R,  315 G and  315 B are formed. It is preferable that the cylindrical lenses  320   a  are formed integral with the upper substrate  320 , which can be achieved by processing the lower surface of the upper substrate  320 . As shown in  FIG. 10 , the cylindrical lenses  320   a  focus the visible light generated in the three discharge cells  314  in which the red (R), green (G) and blue (B) fluorescent layers  315 R,  315 G and  315 B are formed and emit the visible light out of the PDP. Thus, the cylindrical lenses  320   a  on the lower surface of the upper substrate  320 , each corresponding to one pixel, reduce the loss of visible light generated by discharge, thereby enhancing the brightness of the PDP. Also, since each of the cylindrical lenses  320   a  is shared by three discharge cells  314 , the processing of the cylindrical lenses  320   a  is simpler and the PDP can be less expensive to manufacture. 
     On the lower surfaces of the cylindrical lenses  320   a , first and second discharge electrodes  321   a  and  321   b  for sustaining discharge are formed in a pair for each discharge cell  314 . The first and second discharge electrodes  321   a  and  321   b  are formed perpendicular to the address electrodes  311 . On the lower surface of the first and second discharge electrodes  321   a  and  321   b , first and second bus electrodes  322   a  and  322   b , which are preferably made of metal, are formed. Also, a second dielectric layer  323  is formed on the lower surface of the cylindrical lenses  320   a , to cover the first and second discharge electrodes  321   a  and  321   b  and the first and second bus electrodes  322   a  and  322   b . A protective layer  324  is formed on the lower surface of the second dielectric layer  323 . 
     An external light shielding member is provided on the upper surface of the upper substrate  320  to prevent external light from entering the discharge cells  314  through the upper substrate  320 . The external light shielding member is preferably formed of a plurality of parallel stripes  330  (preferably black) on the upper surface of the upper substrate  320  at a predetermined spacing. The stripes  330  are preferably of a uniform width and are parallel with the address electrodes  311  and the cylindrical electrodes  320   a . The stripes  330  are formed where no visible light is emitted by the discharge cells  314 . Non-glare treatments are applied to portions of the upper surface  340  of the upper substrate  320  between the black stripes  330 . The stripes  330  prevent external light from entering the discharge cells  314 , thereby enhancing the contrast of the PDP when used in, for example, brightly lit room conditions. The stripes  330  may include a conductive film for shielding electro magnetic interference (EMI). 
       FIG. 11  is a cross-sectional view illustrating an embodiment of the PDP of  FIGS. 9 and 10 . Referring to  FIG. 11 , a transparent material layer  350  is formed to cover the lower surfaces of the cylindrical lenses  320   a . First and second discharge electrodes  321   a  and  321   b  are formed on the flat lower surface of the transparent material layer  350 . First and second bus electrodes  322   a  and  322   b  are formed on the lower surfaces of the first and second discharge electrodes  321   a  and  321   b . Also, a second dielectric layer  323  is formed on the lower surface of the transparent material layer  350 , to cover the first and second discharge electrodes  321   a  and  321   b  and the first and second bus electrodes  322   a  and  322   b . Thus, the transparent material layer  350  aids in forming the first and second discharge electrodes  321   a  and  321   b  and the first and second bus electrodes  322   a  and  322   b.    
     As described above, the PDP made according to embodiments of the present invention has the following features: 
     First, a plurality of cylindrical lenses corresponds to each discharge cell, reducing the loss of visible lights generated in the discharge cells and enhancing the light integrity and brightness of the PDP. 
     Second, preferably black stripes can cover more of the upper surface of the upper substrate than in the conventional PDP, to more effectively prevent external light from entering the discharge cells, and enhance the contrast of the PDP when used in, for example, Brightly lit room conditions. 
     Third, one cylindrical lens corresponds to two or more discharge cells, making the formation of the cylindrical lenses  320   a  simpler, so that the PDP can be less expensive to manufacture. 
     While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. For example, although the aforementioned embodiments show and describe an AC type surface discharge PDP, the present invention is not limited thereto but can be applied to a DC type PDP or a facing discharge PDP.