Patent Publication Number: US-2007103417-A1

Title: Discharge display having three electrodes formed in a partition-wall plate of the display

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION  
      The application claims the benefit of Korean Patent Application No. 10-2005-0106024, filed on Nov. 7, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a discharge display apparatus, and more particularly to, a discharge display apparatus having a three-electrode type discharge display panel and a driving device for driving the discharge display panel.  
      2. Description of the Related Technology  
       FIG. 1  is an exploded perspective view of a conventional plasma display panel  100  having a three-electrode type surface discharge structure, as disclosed in U.S. Pat. No. 6,903,709.  
      The plasma display panel  100  includes a first substrate  101 , common electrodes  106 , scan electrodes  107 , a first dielectric layer  109 , a protective layer  111 , a second substrate  115 , address electrodes  117 , a second dielectric layer  113 , barrier ribs  114 , and a phosphor layer  110 .  
      The common electrodes  106  and the scan electrodes  107  are covered by the first dielectric layer  109 . The first dielectric layer  109  is covered by the protective layer  111 . The second substrate  115  is disposed to face the first substrate  101 . The address electrodes  117  are arranged parallel to each other on the second substrate  115 . The address electrodes  117  are covered by the second dielectric layer  113 . The barrier ribs  114  are formed on the second dielectric layer  113 . The phosphor layer  110  is formed to cover an upper surface of the second dielectric layer  113  and sidewalls of the barrier ribs  114 .  
      The conventional plasma display panel  100  has certain problems.  
      A large portion (about 40%) of visible rays emitted from the phosphor layer  110  are absorbed by the common electrodes  106 , the scan electrodes  107 , the first dielectric layer  109 , and the protective layer  111  at the bottom of the first substrate  101 , thereby lowering the luminous efficiency of the conventional plasma display panel  100 .  
      Also, when the same image is displayed in the conventional plasma display panel  100  for a long period of time, the phosphor layer  110  is ion-sputtered by charged particles of discharge gas, thereby causing image sticking.  
     SUMMARY OF THE CERTAIN INVENTIVE ASPECTS  
      The present invention provides a discharge display apparatus having a discharge display panel that increases the luminous efficiency of the discharge display apparatus and prevents image sticking, and a driving device that digitally drives the discharge display panel.  
      One embodiment is a discharge display apparatus including a discharge display panel, and a driving device configured to drive the discharge display panel. The discharge display panel includes a partition-wall plate having a plurality of through-cells and being disposed between a first substrate and a second substrate, a plurality of address electrodes, a plurality of common electrodes, and a plurality of scan electrodes, where each electrode is located within the partition-wall plate and substantially surrounds a through-cell. The driving device is configured to divide a single frame into a plurality of subfields, and to perform an addressing operation and a sustaining operation within a single subfield, where the driving device is configured to perform the addressing operation by driving the address electrodes and the scan electrodes, and the driving device is configured to perform the sustaining operation by driving the common electrodes and the scan electrodes.  
      Another embodiment is a discharge display apparatus including a discharge display panel, and a driving device configured to drive the discharge display panel. The discharge display panel includes a first substrate, a second substrate facing the first substrate, a partition-wall plate having through-cells and being disposed between the first and second substrates, and a plurality of address electrodes located in the partition-wall plate, where each address electrode substantially surrounds one or more of the through-cells. The panel also includes a plurality of common electrodes located in the partition-wall plate, each common electrode substantially surrounding one or more of the through-cells, where the common electrodes cross the address electrodes and are disposed between the first substrate and the address electrodes. The panel also includes a plurality of scan electrodes in the partition-wall plate, each common electrode substantially surrounding one or more of the through-cells, where the scan electrodes cross the address electrodes and are disposed between the second substrate and the address electrodes. The driving device is configured to divide a single frame into a plurality of subfields, and to perform an addressing operation and a sustaining operation within a single subfield, where the driving device is configured to perform the addressing by driving the address electrodes and the scan electrodes, and the driving device is configured to perform the sustaining operation by driving the common electrodes and the scan electrodes.  
      Another embodiment is a discharge display including a display panel, the display panel including a partition-wall plate having a plurality of through-cells and being disposed between a first substrate and a second substrate. The panel also includes a plurality of address electrodes, a plurality of common electrodes, and a plurality of scan electrodes, where each electrode is located within the partition-wall plate and substantially surrounds a through-cell. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other features and advantages will become more apparent in the description of certain embodiments with reference to the attached drawings in which:  
       FIG. 1  is an exploded perspective view of a conventional plasma display panel having a three-electrode surface discharge structure;  
       FIG. 2  is an exploded perspective view of a ring-type three-electrode plasma display panel included in a discharge display apparatus according to an embodiment;  
       FIG. 3  is a cross-sectional view of the plasma display panel taken along a line V—V of  FIG. 2 ;  
       FIG. 4  is a perspective view of an array of through-cells and electrodes shown in  FIGS. 2 and 3 , according to an embodiment;  
       FIG. 5  is a block diagram of a driving device that drives the ring-type three-electrode plasma display panel illustrated in  FIG. 2 , according to an embodiment;  
       FIG. 6  is a timing diagram of a method of driving the ring-type three-electrode plasma display panel illustrated in  FIG. 2  in a single frame using the driving device of  FIG. 5 , according to an embodiment;  
       FIG. 7  is a timing diagram of a method of driving the ring-type three-electrode plasma display panel illustrated in  FIG. 2  in a single subfield of  FIG. 6  using the driving device of  FIG. 5 , according to an embodiment; 
    
    
     DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS  
       FIG. 2  is an exploded perspective view of a ring-type three-electrode plasma display panel  200  included in a discharge display apparatus according to an embodiment.  FIG. 3  is a cross-sectional view of the plasma display panel  200  of  FIG. 2 , taken along a line V—V according to an embodiment.  FIG. 4  is a perspective view of an array of through-cells  330  and address electrodes  350 , scan electrodes  360 , and common electrodes  370  illustrated in  FIGS. 2 and 3  according to an embodiment.  
      Referring to  FIGS. 2 through 4 , the plasma display panel  200  includes a first substrate  210 , a second substrate  220 , a partition-wall plate  280 , the address electrodes  350 , the scan electrodes  360 , the common electrodes  370 , a first phosphor layer  225 , a second phosphor layer  226 , and protective layers  215 .  
      The first and second substrates  210  and  220  are formed of a material having high light transmissivity, which may comprise glass as a major constituent thereof. The second substrate  220  is disposed to face the first substrate  210  at a distance from the first substrate  210 . The first and second substrates  210  and  220  may be formed of substantially the same material. In this case, a coefficient of thermal expansion of the first substrate  210  is substantially the same as a coefficient of thermal expansion of the second substrate  220 .  
      The partition-wall plate  280  includes through-cells  330  and a partition wall  214 , and is disposed between the first and second substrates  210  and  220 . According to an embodiment, a cross-section of the through-cells  330  is circular in shape but the shape of the cross-section of the through-cells  330  is not limited to this and may, for example, be triangular, rectangular, pentagonal, oval, or other shapes.  
      The address electrodes  350  have apertures corresponding to the through-cells  330  and are located in the partition wall  214  and are disposed within the partition wall  214  of the partition-wall plate  280 . The address electrodes  350  extend in a second direction, along a y-axis, perpendicular to a first direction, along an x-axis, in which the common electrodes  370  and the scan electrodes  360  extend. Also, the address electrodes  350  are disposed in the partition-wall plate  280 , between the common electrodes  370  and the scan electrodes  360 , in a third direction along a z-axis. As shown in  FIG. 4 , the address electrodes  350  include first loop units  350   a  respectively surrounding the through-cells  330 , and first loop connectors  350   b  connected to the first loop units  350   a.    
      The common electrodes  370  have apertures corresponding to the through-cells  350  and are disposed between the first substrate  210  and the address electrodes  350  within the partition wall  214  and inside the partition-wall plate  280 . The common electrodes  370  extend in the first direction (x-axis direction) and cross the address electrodes  350  which extend in the second direction (y-axis direction). As shown in  FIG. 4  the common electrodes  370  include first loop units  370   a  respectively surrounding the through-cells  330 , and first loop connectors  370   b  connected to the first loop units  370   a.    
      As shown in  FIG. 3 , in the first substrate  210 , grooves  210   a  are respectively formed in regions corresponding to the through-cells  330 , and the first phosphor layer  225  is formed in the grooves  210   a.    
      The protective layers  215  are formed to cover sidewalls of the through-cells  330 . The protective layers  215  prevent the partition wall  214 , the address electrodes  350 , the scan electrodes  360 , and the common electrodes  370  from being damaged by plasma particle sputtering, and emitting secondary electrons to lower a firing discharge voltage. The protective layers  215  may be formed by applying MgO on sides of the partition wall  214 .  
      Since the address electrodes  350 , the scan electrodes  360 , and the common electrodes  370  are embedded into the partition wall  214  in the partition-wall plate  280 , the partition wall  214  may be formed of a dielectric that can induce electric charges to accumulate wall charges.  
      In the ring-type three-electrode plasma display panel  200 , the address electrodes  350 , the common electrodes  370 , and the scan electrodes  360  have advantages because they are at least partially surround the through-cells  330  and are disposed in the partition-wall plate  280 .  
      One advantage is that additional dielectric layers for the address electrodes  350 , the scan electrodes  360  and the common electrodes  370  are not needed, and discharge spaces are formed in the through-cells  330 . Thus, visible rays generated by discharge in the through-cells  330  are emitted directly, thereby increasing the luminous efficiency of the plasma display panel  200 .  
      Another advantage is that the address electrodes  350 , the common electrodes  370 , and the scan electrodes  360  are all ring-shaped electrodes which surround the through-cells  330 , and thus, electric fields from the address electrodes  350 , the scan electrodes  360  and the common electrodes  370  are focused on the centers of the through-cells  330 . Accordingly, even if the same image is displayed in the plasma display panel  200  for a long period of time, the phosphor layers  225  and  226  are not ion-sputtered by charged particles of discharge gas, thereby preventing image sticking.  
      Another advantage is that since the address electrodes  350 , the common electrodes  370 , and the scan electrodes  360  are all ring-shaped electrodes which surround the through-cells  330 , discharge can occur throughout substantially the entirety of each of the through-cells  330 . Thus, the discharge response speed and the discharge efficiency of the plasma display panel  200  are increased.  
      Another advantage is that the address electrodes  350 , the scan electrodes - 360 , and the common electrodes  370  are formed on the sides of the through-cells  330 , as opposed to the conventional placement on the first and second substrates  210  and  220  through which visible rays are required to pass. Therefore, the address electrodes  350 , the scan electrodes  360 , and the common electrodes  370  need not be formed of a transparent conductor, such as Indium-Tin-Oxide (ITO) which has a large resistance. Thus, the address electrodes  350 , the scan electrodes  360 , and the common electrodes  370  may be formed of metal having a small resistance, thereby increasing the discharge response speed and the discharge efficiency of the plasma display panel  200 .  
       FIG. 5  is a block diagram of a driving device that drives the ring-type three-electrode plasma display panel  200  illustrated in  FIG. 2 , according to an embodiment of the present invention. Referring to  FIG. 5 , the driving device includes a video processor  66 , a controller  62 , an address driver  63 , an X driver  64 , and a Y driver  65 .  
      The video processor  66  transforms external video signals, e.g., a video signal SVID and a digital-television (TV) signal SDTV, into internal digital video signals. Examples of the internal digital video signals include 8-bit red (R), green (G), and blue (B) video data, a clock signal, a vertical synchronization signal, and a horizontal synchronization signal.  
      The controller  62  generates data signals SA, X control signals SX, and Y control signals SY in response to the internal video signals from the video processor  66 .  
      The address driver  63  drives the address electrodes  350  of the plasma display panel  200  in response to the data signals SA from the controller  62 . The X driver  64  drives the common electrodes  370  of the plasma display panel  200  in response to the X control signals SX from the controller  62 . The Y driver  65  drives the scan electrodes  360  of the plasma display panel  200  in response to the Y control signals SY from the controller  62 .  
      The driving device divides a single frame into a plurality of subfields, and performs addressing and sustaining operations in single subfields. Specifically, the driving device performs the addressing operation by driving the address electrodes  350  and the scan electrodes  360 , and performs the sustaining operation by driving the common electrodes  370  and the scan electrodes  360 . Thus, since time-division driving in a single frame is possible, the ring-type three-electrode plasma display panel  200  can be digitally driven, which will now be described with reference to  FIGS. 6 and 7 .  
       FIG. 6  is a timing diagram of a method of driving the ring-type three-electrode plasma display panel  200  using the driving device of  FIG. 5  in a single frame FR 1 . In  FIG. 6 , reference numerals Y 1  through Yn denote the scan electrodes  360  of  FIG. 2  that are sequentially scanned.  
      As illustrated in  FIG. 6 , each single frame is divided into eight subfields SF 1 , . . . , SF 8  to obtain a time-ratio gray-scale control display, wherein the single frame is divided into the plurality of the subfields so that the time of each of the subfields is substantially proportional to an applied gray-scale weight. In some embodiments, the driving single frame is divided into the plurality of subfields so that a period of time for the sustaining operation in each of the subfields is substantially proportional to the applied given gray-scale weight.  
      Also, each of the subfields SF 1 , . . . , SF 8  is divided into initialization periods R 1 , . . . , R 8 , address periods A 1 , . . . , A 8 , and sustain periods S 1 , . . . , S 8 .  
      Discharge conditions in all of the through-cells  330  of  FIG. 2  are controlled to be suitable for addressing which is performed after the through-cells  330  are initialized in each of the initialization periods R 1 , . . . , R 8 .  
      In each of the address periods A 1 , . . . , A 8 , display data signals are sequentially supplied to the address electrodes  350 , while scan pulses are sequentially supplied to the scan electrodes Y 1 , . . . , Y n    360 . Wall charges are formed in corresponding through-cells  330  when logic high display data signals are applied to the corresponding through-cells  330  during application of the scan pulses.  
      In each of the sustain periods S 1 , . . . , S 8 , sustain-discharge pulses are alternately applied to the scan electrodes Y 1 , . . . , Y n    360  and the common electrodes  370 , thus causing display discharge in the through-cells  330  in which the wall charges have been formed in the corresponding address period A 1 , . . . , or A 8 . Thus, the brightness of the emitted light in the respective through-cells  330  in the plasma display panel  200  is proportional to the length of each of the sustain periods S 1 , . . . , S 8  of the single frame FR 1 . The total length of the sustain periods S 1 , . . . , S 8  of the single frame FR 1  is 255T where T denotes a unit of time. Therefore, it is possible to display 256 gray scales including a zero gray scale during which no light is emitted in the single frame FR 1 .  
      In  FIG. 6 , 1T, corresponding to 2 0 , is set for the sustain period S 1  of the first subfield SF 1 . 2T, corresponding to 2 1 , is set for the sustain period S 2  of the second subfield SF 2 . 4T, corresponding to 2 2 , is set for the sustain period S 3  of the third subfield SF 3 . 8T, corresponding to 2 3 , is set for the sustain period S 4  of the fourth subfield SF 4 . 16T, corresponding to 2 4 , is set for the sustain period S 5  of the fifth subfield SF 5 . 32T, corresponding to 2 5 , is set for the sustain period S 6  of the sixth subfield SF 6 . 64T, corresponding to 2 6 , is set for the sustain period S 7  of the seventh subfield SF 7 . 128T, corresponding to 2 7 , is set for the sustain period S 8  of the eighth subfield SF 8 .  
      Therefore, if a subfield to be displayed is properly selected from the eight subfields SF 1  through SF 8 , a time-division display with 256 gray scales can be obtained.  
       FIG. 7  is a timing diagram of a method of driving the ring-type three-electrode plasma display panel  200  illustrated in  FIG. 2  during a single subfield SF, which is one of the subfields SF 1  through SF 8  of  FIG. 6 , using the driving device of  FIG. 5 . In  FIG. 7 , reference numerals S AR1 , . . . ,  ABm  denote driving signals supplied to the address electrodes  350  of  FIG. 2 , reference numerals S X1 , . . . ,  Xn  denote driving signals supplied to the common electrodes  370  of  FIG. 2 , and reference numerals S Y1 , . . . , S Yn  denote driving signals supplied to the scan electrodes  360  of  FIG. 2  (or the scan electrodes Y 1 , . . . , Y n  of  FIG. 6 ).  
      Referring to  FIG. 7 , during a first period from t 1 , to t 2 , a voltage applied to the common electrodes  370  is increased from a ground voltage V G  to a second voltage V S  in an initialization period R of the single subfield SF. During the initialization period, the ground voltage V G  is applied to the scan electrodes  360  and the address electrodes  350 . Thus, a weak discharge occurs in a discharge region between the common electrodes  370  and the scan electrodes  360  Y 1 , . . . , Y n , and in a discharge region between the common electrodes  370  and the address electrodes  350 , and thus, negative wall charges are formed around the common electrodes  370 .  
      During a second period, from t 2  to t 3 , in the initialization period R where wall charges are accumulated, a voltage applied to the scan electrodes  360  Y 1 , . . . , Y n  is continuously increased from the second voltage V S  to a first voltage V SET +V S  that is higher by a fourth voltage V SET  than the second voltage V S . During this period, the ground voltage V G  is applied to the common electrodes  370  and the address electrodes  350 . Thus, a weak discharge continues to occur in the discharge region between the scan electrodes  360  Y 1 , . . . , Y n  and the common electrodes  370 , and in a discharge region between the scan electrodes  360  Y 1 , . . . , Y n  and the address electrodes  350 . Accordingly, a large amount of negative wall charges are formed around the scan electrodes  360  Y 1 , . . . , Y n , and a large amount of positive wall charges are formed around the common electrodes  370  and the address electrodes  350 .  
      During a third period, from t 3  to t 4 , in the initialization period R when wall charges are all present, a voltage applied to the scan electrodes  360  Y 1 , . . . , Y n  is continuously reduced from the second voltage V S  to the ground voltage V G , i.e., a third voltage, while a voltage applied to the common electrodes  370  is maintained at the second voltage V S . During this period, the ground voltage V G  is applied to the address electrodes  350 . Thus, a weak discharge continuously occurs in the discharge region between the address electrodes  370  and the scan electrodes  360  Y 1 , . . . , Y n , and thus, some of the negative wall charges accumulated around the scan electrodes  360  Y 1 , . . . , Y n  move to surround the common electrodes  370 . Accordingly, the wall electric-potential of the common electrodes  370  is lower than that of the address electrodes  350  but is higher than that of the scan electrodes  360  Y 1 , . . . , Y n . During this period, an address voltage V A -V G  needed for an opposed discharge between the address electrodes  350  and the scan electrodes  360  Y 1 , . . . , Y n  selected during the earlier address period A, may be lowered.  
      During the earlier address period A, display data signals are respectively supplied to the address electrodes  350 , and scan pulses having the ground voltage V G  are sequentially applied to the scan electrodes  360  Y 1 , . . . , Y n  that are biased to a fifth voltage V SCAN  lower than the second voltage V s , thereby performing advantageous addressing. If the through-cells  330  of  FIG. 2  are selected, a positive address voltage V A  is applied to the display data signals that are respectively applied to the address electrodes  350 . If the through-cells  330  of  FIG. 2  are not selected, the ground voltage V G  is applied to the display data signals respectively applied to the address electrodes  350 . While scan pulses of the ground voltage V G  are applied, the display data signals having the positive address voltage V A  are supplied, address discharge forms wall charges in only the corresponding through-cell  330 . For more precise and efficient address discharge, the common electrodes  370  X 1 , . . . , X n  are maintained at the second voltage V S .  
      During a sustain period S subsequent to the address period A, sustain pulses of the second voltage V S  are alternately applied to all of the scan electrodes  360  Y 1 , . . . , Y n  and the common electrodes  370 , thus causing sustain discharge in the corresponding through-cells  330  where the wall charges are formed during the address period A.  
      As described above the plasma display panel  200  of  FIG. 2  can be digitally driven with time-division driving during a single frame.  
      As described above, a discharge display apparatus according to an embodiment in which address electrodes, common electrodes, and scan electrodes are all ring-shaped electrodes which surround through-cells and are disposed in a partition-wall plate has advantages.  
      One advantage is that additional dielectric layers for electrodes are not needed and discharge regions are formed in the through-cells, and thus, visible rays generated due to discharge in the through-cells are emitted directly, thereby increasing the luminous efficiency of the discharge display apparatus.  
      Also, electric fields of the electrodes are focused on the centers of the through-cells. Thus, even if the same image is displayed in the discharge display apparatus for a long amount of time, a phosphor layer is not ion-sputtered by charged particles of discharge gas, thereby preventing image sticking.  
      Furthermore, discharge can occur throughout each of the through-cells, thereby increasing the discharge response speed and the discharge efficiency of the discharge display apparatus.  
      Also, the electrodes are disposed on the sides of the through-cells that are discharge regions, not first and second substrates through which visible rays pass. Therefore, the address, scan and common electrodes need not be formed of a transparent conductor that has a large resistance. Thus, the address, scan and common electrodes can be formed of metal having a small resistance, thereby increasing the discharge response speed and the discharge efficiency of the discharge display apparatus.  
      A driving device, of a discharge display apparatus according to an embodiment divides a single frame into a plurality of subfields and performs addressing and sustaining operations in a single subfield. Specifically, the addressing operation is performed by driving address electrodes and scan electrodes, and the sustaining operation is performed by driving common electrodes and scan electrodes. Therefore, time-division driving can be performed within a single frame, and thus, a discharge display panel can be digitally driven. While the present invention has been particularly shown and described to embodiments thereof, it will be understood by those of ordinary skill in the changes in form and details may be made therein without departing from the of the present invention.