Patent Publication Number: US-2007096650-A1

Title: Plasma display panel

Description:
BACKGROUND OF THE INVENTION  
      This application claims the priority of Korean Patent Application No. 10-2005-0103460, filed on Oct. 31, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.  
     FIELD OF THE INVENTION  
      The present embodiments relate to a plasma display panel (PDP), and more particularly, to a PDP having a new structure that can be easily manufactured  
     DESCRIPTION OF THE RELATED ART  
      Plasma display panels (PDP) have recently replaced conventional cathode ray tube (CRT) display devices. In a PDP, a discharge gas is sealed between two substrates on which a plurality of discharge electrodes are formed, a discharge voltage is applied, phosphor formed in a predetermined pattern by ultraviolet rays generated by the discharge voltage is excited whereby a desired image is obtained.  
      In order to make the PDP highly precise and fine, a discharge space in which a discharge occurs should be very small. However, as the discharge space is reduced, a process of forming a phosphor layer in the discharge space cannot be easily performed. In addition, barrier ribs that partition the discharge space are generally formed using a sandblasting process. It is very difficult to manufacture highly precise and fine barrier ribs using the sandblasting process. Furthermore, the number of processes of manufacturing the PDP is very large, which increases manufacturing time and costs.  
     SUMMARY OF THE INVENTION  
      The present embodiments provide a plasma display panel (PDP) having a new structure that can be easily manufactured.  
      According to an aspect of the present embodiments, there is provided a plasma display panel including: a substrate; and a shell structure disposed on the substrate and having a shell and a discharge gas filled in the shell.  
      According to another aspect of the present embodiments, there is provided a plasma display panel including: a first substrate and a second substrate separated from each other by a predetermined gap and opposing each other; barrier ribs disposed between the first substrate and the second substrate and partitioning a plurality of discharge cells; discharge electrode pairs causing a discharge in the discharge cells; and shell structures disposed inside the discharge cells and having a discharge gas filled in the shell. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other aspects and advantages of the present embodiments will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:  
       FIG. 1  is a partially cutaway and exploded perspective view of a plasma display panel (PDP) according to an embodiment;  
       FIG. 2  is a cross-sectional view taken along line II-II of  FIG. 1 ;  
       FIGS. 3A and 3B  show photos of a shell manufactured using MgF 2 ;  
       FIGS. 4A through 4G  illustrate a method of manufacturing the PDP illustrated in  FIG. 1 ;  
       FIG. 5  shows a photo of a resultant structure in which a second substrate and barrier ribs are integrated into a single unit using the method illustrated in  FIGS. 4A through 4G ;  
       FIG. 6  is a partially cross-sectional view of a modified example of the PDP illustrated in  FIG. 1 ;  
       FIG. 7  is a partially cutaway and exploded perspective view of a PDP according to another embodiment; and  
       FIG. 8  is a cross-sectional view taken along line VIII-VIII of  FIG. 7 .  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The present embodiments will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments are shown. Like reference numerals denote like elements.  
       FIGS. 1 and 2  illustrate a plasma display panel (PDP)  100  according to an embodiment.  FIG. 1  is a partially cutaway and exploded perspective view of the PDP  100 , and  FIG. 2  is a cross-sectional view taken along line II-II of  FIG. 1 .  
      The PDP  100  includes a first substrate  110  and a second substrate  120  that oppose each other and are combined with each other. The first substrate  110  and the second substrate  120  are separated from each other by a predetermined gap and define red, green, and blue discharge cells  170  corresponding to red, green, and blue subpixels. The first substrate  111  and the second substrate  120  may be formed of a flexible material. Various flexible materials may be used. The first substrate  110  and the second substrate  120  may include silicon rubber, polydimethylsiloxane (PDMS) or polyester. However, the present embodiments are not limited to this and the first substrate  110  and the second substrate  120  may also be formed of glass.  
      A plurality of discharge electrode pairs  115  in which a discharge occurs in discharge cells  170  are disposed between the first substrate  110  and the second substrate  120 . Each discharge electrode pair  115  includes a first electrode  111  and a second electrode  112  which extend to cross each other. A detailed description thereof will now be described.  
      First electrodes  111  are disposed on an inner side surface of the first substrate  110 . The first electrodes  111  are separated from one another by a predetermined gap and extend to be parallel to one another. One first electrode  111  corresponds to each discharge cell  170 , extends along a first direction (x direction) and has a striped shape. In addition, the first electrodes  111  may be formed, for example, of indium tin oxide (ITO) for visible rays transmission ratio improvement. Since, in ITO, large voltage drop occurs in a lengthwise direction, an additional bus electrode may be disposed on the ITO.  
      Second electrodes  112  are disposed on an inner side surface of the second substrate  120 . The second electrodes  112  are separated from one another by a predetermined gap and extend to be parallel to one another. One second electrode  112  corresponds to each discharge cell  170 , extends along a second direction (y direction) that crosses the first direction (x direction) and has a striped shape. In addition, the second electrodes  112  may be formed, for example, of indium tin oxide (ITO) for visible rays transmission ratio improvement. Like in the first electrodes  111 , an additional bus electrode may be disposed on the ITO.  
      The discharge cells  170  are partitioned by barrier ribs  130  interposed between the first substrate  110  and the second substrate  120 . The barrier ribs  130  define a space in which shell structures  150  will be arranged. Referring to  FIG. 1 , the barrier ribs  130  have a striped shape that extends along the second direction (y direction). The discharge cells  170  are disposed in a matrix arrangement by the barrier ribs  130 . The barrier ribs  130  may be separately formed independent of the first substrate  110  and the second substrate  120 . However, for the convenience of manufacture, the barrier ribs  130  may be integrated with the first substrate  110  or the second substrate  120 . In  FIGS. 1 and 2 , the barrier ribs  130  and the second substrate  120  are integrated into a single unit.  
      The shell structures  150  are disposed inside the discharge cells  170 . One shell structure  150  may be disposed in each discharge cell  170  or a plurality of shell structures  150  may be disposed in each discharge cell  170 . Each shell structure  150  includes a shell  151 , a discharge gas (not shown), and a phosphor layer  152 . The shell  151  defines a space  180  in which a discharge occurs and has a spherical shape. A discharge gas is sealed in the space defined by the shell  151 . When voltage is applied to the first electrode  111  and the second electrode  112 , a discharge occurs. The discharge gas may include an inert gas including Xe, Kr, Ne, Ar, and He or a mixture thereof or at least one of Hg, N 2 , and D 2 .  
      The shell  151  seals the discharge gas and may be formed of a material including MgF 2 , MgO or Si 3 N 4 . Such materials have a high transmission ratio of UV rays generated by the discharge gas and stabilizing properties. In particular, the shell  151  may be formed of MgF 2 . This is because a UV rays transmission ratio of MgF 2  having a wavelength less than about 250 nm is higher through MgF 2  than other materials. When the discharge gas includes at least one of Hg, N 2 , and D 2 , the shell  151  may be formed of a material including MgF 2 , MgO or Si 3 N 4  having a high transmission ratio in a long wavelength region since UV rays generated by the discharge gas have a long wavelength greater than about 250 nm.,  
      Characteristics of the shell  151  and a method of manufacturing the same are disclosed in U.S. Pat. Nos. 6,669,961, 6,073,578, 6,060,128, 5,948,483, and 5,344,676, and U.S. patent application Publication Nos. 20050123614, 20040022939, and 20020054912, each of which is hereby incorporated in its entirety by reference. Photos of a shell manufactured using MgF 2  are shown in  FIGS. 3A and 3B . The shell  151  can be manufactured using micro sphere manufacturing technology disclosed in U.S. Pat. No. 6,669,961, which is hereby incorporated in its entirety by reference. The size of the shell  151  can have a diameter from about 1 micron to about 1000 microns.  
      Phosphor layers  152  producing red, green, and blue light are formed on an outer surface of the shell  151 . The phosphor layers  152  include components that emit visible rays from ultraviolet (UV) rays. The phosphor layers  152  formed in red discharge cells include phosphor such as Y(V,P)O 4 :Eu, the phosphor layers  152  formed in green discharge cells include phosphor such as Zn 2 SiO 4 :Mn, and the phosphor layers  152  formed in blue discharge cells include phosphor such as BAM:Eu.  
      A method of manufacturing the PDP  100  having the above structure will now be described with reference to  FIGS. 4A through 4G .  
      Referring to  FIG. 4A , a mold  180  having a shape in which the second substrate  120  and the barrier ribs  130  can be integrated into a single unit is prepared. Next, liquid silicon rubber  181  is injected into the mold  180  in the vacuum state.  FIG. 4B  illustrates a state where the liquid silicon rubber  181  is injected into the mold  180 . The silicon rubber  181  is a two-liquid type silicon rubber and formed by mixing a main agent and a hardener. Referring to  FIG. 4B , first, the main agent and the hardener are mixed in the mold  180  at a ratio of approximately 10:1 and vapors in the mixture are sufficiently removed in the vacuum state. The process of removing vapors is performed under a vacuum chamber for about 40 minutes. At this time, the vacuum state should be maintained for a sufficient time so that any extra space is completely filled in a processed groove  180   a.    
      After that, the silicon rubber  181  is solidified. The process of solidifying the silicon rubber  181  is performed in such a manner that the liquid silicon rubber  181  of which vapors are removed is cured at a hot air drying furnace of approximately 40° C. for about one hour. Next, referring to  FIG. 4C , the solidified silicon rubber  181  is removed from the mold  180 , thereby manufacturing the second substrate  120  and the barrier ribs  130  to be integrated into a single unit. A resultant structure in which the second substrate  120  and the barrier ribs  130  are integrated into a single unit using the process is illustrated in  FIG. 5 .  
      After the second substrate  120  and the barrier ribs  130  are manufactured, the second electrodes  112  are patterned on the second substrate  120 .  FIG. 4D  illustrates a state where the second electrodes  112  are formed on the second substrate  120 .  
      Next, a process of inserting the shell structures  150  into the red, green, and blue discharge cells  170  using a mask  183  is performed. A method of manufacturing the shell structures  150  will now be described. A spherical shell  151  having a diameter from about 1 micron to about 1000 microns is manufactured in a chamber in which the discharge gas such as Xe is filled, using micro sphere manufacturing technology disclosed in U.S. Pat. No. 6,669,961 by Kim, et al. issued Dec. 30, 2003, (hereby incorporated in its entirety by reference). After that, phosphor layers  152  are formed on an outer surface of the shell  151  using a spraying or dipping method. As shown in  FIG. 4E , after shell structures  150 R for red shell structures are formed, the mask  183  is disposed on the barrier ribs  130 . The mask  183  has three shapes, so as to insert shell structures  150 R,  150 G, and  150 B for red, green, and blue shell structures into the red, green, and blue discharge cells  170 R,  170 G, and  170 B, respectively. The mask  183  illustrated in  FIG. 4E  is used for the shell structures  150 R for emitting red light disposed in the red discharge cells  170 B. Referring to  FIG. 4E , an opening  183   a  is formed only in a portion of the mask  183  which corresponds to the red discharge cells  170 R. In addition, each shell structure  150 R for emitting red light includes a shell  151 , a red light emitting phosphor layer  152 R, and a discharge gas. Thus, if all of the shell structures  150 R for emitting red light are filled in the red discharge cells  170 R, the mask  183  of which opening  183   a  is formed in a position corresponding to the red or blue discharge cells  170 G or  170 B is disposed on the barrier ribs  130  so that the shell structures  150 G for emitting green light and the shell structures  150 B for emitting blue light are filled in the green discharge cells  170 G and the blue discharge cells  170 B, respectively.  FIG. 4F  illustrates a state where all of the shell structures  150 R,  150 G, and  150 B are filled in each of the discharge cells  170 R,  170 G, and  170 B.  
      Next, referring to  FIG. 4G , the resultant structure illustrated in  FIG. 4F  is combined with the inner surface of the first substrate  110  in which the first electrodes  111  are patterned. The first substrate  110  may be formed of silicon rubber. Since the first substrate  110 , the second substrate  120 , and the barrier ribs  130  have flexibility and buffering characteristics, when the first substrate  110  and the second substrate  120  are pressurized and combined with each other, the shell structures  150 R,  150 G, and  150 B can be fixed in the discharge cells  170 R,  170 G, and  170 B.  
      The operation of the PDP  100  having the above structure according to the present embodiments will now be described.  
      An address voltage is applied between the first electrode  111  and the second electrode  112  so that an address discharge occurs. Discharge cells  170  in which a sustain discharge will occur as a result of the address discharge are selected. After that, if a sustain voltage is applied between the first electrode  111  and the second electrode  112  of the selected discharge cells  170 , a sustain discharge occurs in the discharge space  180 . The energy level of the excited discharge gas during the sustain discharge is reduced and UV rays are emitted. The UV rays excite the phosphor layers  152  coated on the outer side surface of the shell  151  after transmitting through the shell  151 . The energy level of the excited phosphor layers  152  is reduced, visible rays are emitted, and the emitted visible rays constitute an image.  
       FIG. 6  depicts a partially cross-sectional view of a modified example of the PDP  100  illustrated in  FIG. 1 .  FIG. 6  shows a plurality of shell structures  150 R′,  150 G′, and  150 B′ disposed in each of red, green, and blue discharge cells  170 R′,  170 G′, and  170 B′, which will now be described.  
      The red, green, and blue discharge cells  170 R′,  170 G′, and  170 B′ are partitioned by stripe-shaped barrier ribs. The three red, green, and blue light emitting shell structures  150 R′,  150 G′, and  150 B′ are disposed in the red, green, and blue discharge cells  170 R′,  170 G′, and  170 B′, respectively. Detailed structure and functions of the red, green, and blue light emitting shell structures  150 R′,  150 G′, and  150 B′ are similar to the above description and thus will be omitted. The shell structures  150 R′,  150 G′, and  150 B′ may have a diameter from about 1 micron to about 1000 microns.  
      As described above, since a plurality of shell structures is disposed in one discharge cell, a space in the discharge cells can be more frequently used and defects that may occur in the shell structures can be reduced.  
      A PDP  200  according to another embodiment will now be described with reference to  FIGS. 7 and 8 .  FIG. 7  is a partially cutaway and exploded perspective view of the PDP  200 , and  FIG. 8  is a cross-sectional view taken along line VIII-VIII of  FIG. 7 .  
      The first substrate  210  and the second substrate  220  are separated from each other by a predetermined gap and oppose each other. Barrier ribs  230  having a striped shape and partitioning a plurality of discharge cells  270  are disposed between the first substrate  210  and the second substrate  220 . The barrier ribs  230  and the second substrate  220  are integrated into a single unit. Characteristics of the first substrate  210 , the second substrate  220 , and the barrier ribs  230  and a method of manufacturing the same are similar to those illustrated in  FIG. 6  and thus will be omitted.  
      A plurality of discharge electrode pairs  215  extends on the first substrate  210  that opposes the second substrate  220 , to be parallel to one another. Each discharge electrode pair  215  corresponds to each discharge cell  270  and includes a first discharge electrode  211  and a second discharge electrode  212 . Address electrodes  213  are disposed on the second substrate  220  that opposes the first substrate  210  and extend to cross the discharge electrode pairs  215 .  
      Referring to  FIG. 8 , shell structures  250  are disposed inside the discharge cells  270 . Each shell structure  250  includes a spherical shell  251 , phosphor layers  252  coated on an outer surface of the shell  251 , and a discharge gas filled in a discharge cell  280  inside the shell  251 . Referring to  FIG. 8 , one shell structure  250  corresponds to each discharge cell  270 . However, the present embodiments are not limited to this and a plurality of shell structures  250  may be disposed in each discharge cell  270 . The structure and function of the shell structure  250  are similar to those illustrated in  FIG. 6  and thus will be omitted.  
      An address voltage is applied between the first discharge electrode  211  and the address electrode  213  so that an address discharge occurs. Discharge cells  270  in which a sustain discharge will occur as a result of the address discharge are selected. After that, if a sustain voltage is applied between the first electrode  211  and the second electrode  212  of the selected discharge cells  270 , a sustain discharge occurs in the discharge space  280 . The energy level of the excited discharge gas during the sustain discharge is reduced and UV rays are emitted. The UV rays excite the phosphor layers  252  coated on the outer side surface of the shell  251  after transmitting through the shell  251 . The energy level of the excited phosphor layers  252  is reduced, visible rays are emitted, and the emitted visible rays constitute an image.  
      The PDP according to the present embodiments has the following effects. First, since an image is realized by arranging the shell structure having a diameter from about 1 micron to about 1000 microns in the discharge cells, the PDP can be simply manufactured to be highly precise and fine. In particular, a method of coating the phosphor layers is simple and a process of forming an additional dielectric layer is unnecessary.  
      Second, when the second substrate and the barrier ribs are integrated into a single unit using silicon rubber, the PDP can be simply manufactured and has flexibility. In particular, since the barrier ribs are formed using a molding process, it is advantageous to make the PDP highly precise and fine.  
      While the present embodiments have 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 embodiments as defined by the following claims.