Abstract:
A plasma display panel includes designed to improve optical efficiently and to reduce misdischarging between discharge cells. The address electrodes have varying widths so that they are narrow in discharge cells and are relatively wide outside of discharge cells. Discharge gas filling the discharge cells have an elevated Xe content, preferably 10 to 30%. Other variations further include having striped and matrix patterned barrier ribs, forming the discharge sustain electrodes in tabs extending in pairs into the middle of the discharge cells, and varying the width of address electrodes at various locations outside of the discharge cells.

Description:
CLAIM OF PRIORITY 
   This application makes reference to and claims all benefits accruing under 35 U.S.C. §119 from an application for PLASMA DISPLAY PANEL earlier filed in the Korean Intellectual Property Office on the 4th day of September 2003 and there duly assigned Serial No. 2003-61862. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a plasma display panel, and in particular, to a plasma display panel with an improved structure for address electrode that prevents mis-discharging in discharge cells, especially in plasma display panels with high definition. 
   2. Description of Related Art 
   Generally, a plasma display panel (referred to hereinafter simply as a “PDP”) is a display device which displays images by exciting phosphors with vacuum ultraviolet rays generated due to discharging of gas within a discharge cell. PDPs are classified into an alternating current type and a direct current type, depending upon the voltage application, and into a face discharge type and a surface discharge type, depending upon the forms of electrode construction. Recently, an alternating current type of PDP with a triode surface discharge structure has been used extensively. 
   However, as PDP&#39;s become more high definition and thus the structures within the display become smaller, a growing problem of mis-discharging or an accidental discharge is becoming more severe. What is needed is a design for a PDP that reduces or eliminates the problem of mis-discharging in high definition PDP&#39;s. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide an improved design for a PDP. 
   It is also an object of the present invention to provide an improved design for a PDP that reduces mis discharging between discharge cells when the PDP is a high definition display with elevated levels of Xe gas in the discharge cells. 
   It is also an object of the present invention to provide improved electrode design in a PDP to prevent inter discharge cell discharging for high definition PDPs. 
   It is further an object of the present invention to provide a PDP which inhibits interaction between the address electrode and the display electrode, increases the content of Xe in the discharge gas, and allows precise driving thereof without incurring abnormal inter-cell discharging. 
   These and other objects may be achieved by a PDP with the following features. According to one aspect of the present invention, the PDP includes first and second substrates facing each other with a distance therebetween. Address electrodes are formed on the first substrate, and barrier ribs are disposed between the first and the second substrates to partition the discharge cells. A phosphor layer is formed within the respective discharge cells. Discharge sustain electrodes are formed on the second substrate. When the distance between the portions of the discharge sustain electrode at the respective discharge cells is called a main discharge gap, and the distance between the discharge sustain electrodes at the two neighboring discharge cells is called a non-discharge gap, the width of the address electrode in the vicinity of the main discharge gap is smaller than the width of the address electrode in the vicinity of the non-discharge gap. The width of the address electrode corresponding to the main discharge gap is 40˜140 μm. The discharge cell is internally filled with a discharge gas containing 10˜30% of Xe. 
   The address electrode corresponding to the non-discharge gap is partially differentiated in the longitudinal direction thereof. The width of the address electrode corresponding to the center of the non-discharge gap can be made to be smaller than the width of the address electrode corresponding to both end portions of the non-discharge gap. The width of the address electrode corresponding to the center of the non-discharge gap can be made to have substantially the same width as the width of the address electrode corresponding to the main discharge gap. 
   According to another aspect of the present invention, the PDP includes first and second substrates facing each other with a distance therebetween. Address electrodes are formed on the first substrate. Barrier ribs are disposed between the first and the second substrates to partition the discharge cells, and a phosphor layer is formed within the respective discharge cells. Discharge sustain electrodes are formed on the second substrate. Each discharge sustain electrode has a scanning electrode and a display electrode. When a horizontal axis line drawn on the center of the scanning electrode and is called a first horizontal axis line, a horizontal axis line drawn on the center of the display electrode is called a second horizontal axis line, a section between the first and the second horizontal axis lines within any single discharge cell is called a main discharge section, and a section between the first and the second horizontal axis lines of neighboring discharge cells is called a non-discharge section, the width of the address electrode in the main discharge section is smaller than the width of the address electrode in the non-discharge section. 
   The address electrode corresponding to the non-discharge section can be partially differentiated in the longitudinal direction thereof. The width of the address electrode corresponding to the center of the non-discharge section can be made to be smaller than the width of the address electrode corresponding to both end portions of the non-discharge section. The width of the address electrode corresponding to the center of the non-discharge section is substantially the same as the width of the address electrode corresponding to the main discharge section. The barrier ribs are stripe-patterned, and parallel to the address electrodes. The barrier ribs can also be lattice-shaped with a first barrier rib portion proceeding in the direction of the address electrode, and a second barrier rib portion proceeding in the direction of the discharge sustain electrode. The scanning electrode and the display electrode each have a transparent portion, and a bus portion formed on one side periphery of the transparent portion and being electrically connected to the transparent portion. The transparent portions can be protruded toward the center of the respective discharge cells, and face each other in pairs. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention, and many of the 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 indicates the same or similar components, wherein: 
       FIG. 1  is a partial exploded perspective view of a PDP; 
       FIG. 2  is a partial exploded perspective view of a PDP according to an embodiment of the present invention; 
       FIG. 3  is a partial plan view of the PDP illustrated in  FIG. 2 , illustrating the combined structure thereof; 
       FIG. 4  is a partial sectional view of the PDP illustrated in  FIG. 2 , illustrating the combined structure thereof; 
       FIG. 5  is a waveform diagram illustrating a method of driving the PDP according to an embodiment of the present invention; 
       FIGS. 6 and 7  are partial plan views and of variants of the PDP according to an embodiment of the present invention; and 
       FIGS. 8 and 9  are a partial exploded perspective view and a partial plan view of another variant of the PDP according to an embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Turning now to the figures,  FIG. 1  illustrates an alternating current type PDP  100 . PDP  100  of  FIG. 1  includes an address electrode  3 , a barrier rib  5 , and a phosphor layer  7  formed on a rear substrate  1  at respective discharge cells. On the front substrate  9  is formed a discharge sustain electrode  15  which is a scanning electrode  11  paired with a display electrode  13 . Dielectric layers  17  and  19  cover the address electrode  3  and the discharge sustain electrode  15 , respectively. The discharge cell is internally filled with a discharge gas (mainly a mixture gas of Ne—Xe). In PDP  100  of  FIG. 1 , an MgO protective layer  21  is formed to cover dielectric layer  19 . 
   In the PDP  100  of  FIG. 1 , when an address voltage Va is applied between the address electrode  3  and the scanning electrode  11 , address discharging occurs within the discharge cell so that wall charges build up on the dielectric layer  19  near the scanning and the display electrodes  11  and  13  as well as on the dielectric layer  17  near the address electrode  3 , thus selecting the discharge cells to emit light. Thereafter, a sustain voltage Vs is applied between the scanning electrode  11  and the display electrode  13  causing wall charges accumulated near the scanning electrode  11  to collide with charges accumulated near the display electrode  13  to thereby generate a plasma discharge or a sustain discharge. At this time, vacuum ultraviolet rays are emitted from the excited atoms of Xe during the plasma discharging. The vacuum ultraviolet rays excite the phosphor layers  7  to emit visible rays, and display color images. 
   With the PDP  100 , in the case that the barrier ribs  5  are stripe-patterned, the interiors of the discharge cells are connected to each other in the direction of the address electrodes  3  (i.e., the y-direction). Consequently, the space (or wall) charges are able to migrate to the interiors of the neighboring discharge cells in this y-direction, causing inter-cell discharging. Furthermore, in case the barrier ribs  5  are formed with other patterns, the discharging of some discharge cells can affect the neighboring discharge cells in the y-direction of the address electrodes, thereby causing abnormal inter-cell discharging. 
   In recent years, PDPs are more and more being designed to have a high definition structure, and the inter-cell pitch has thus shortened, further exacerbating the inter-cell abnormal discharging problem. Particularly when the address electrodes  3  are in a stripe-patterned as in  FIG. 1  with a uniform longitudinal width, portions of the address electrodes  3  that face the scanning electrodes  11  can induce the address discharging with a predetermined distance thereto, and to the display electrode  13  not committed to the address discharging with a predetermined distance thereto. With such a structure, when the PDP is operated, even after the reset interval of deleting the information memorized at the discharge cells, wall discharges are liable to be generated in the discharge cells due to the interaction between the address electrode  3  and the display electrode  13 , thereby causing abnormal discharging. 
   Meanwhile, in the field of plasma displays, in order to enhance the discharge efficiency, a content of Xe in the discharge gas is increased to increase the intensity of the vacuum ultraviolet rays. However, when only the content of Xe is increased without improving the internal structure of the PDP, the driving voltage of the PDP needs to be elevated, causing the power consumption thereof to increase. Furthermore, as the content of Xe is increased, the abnormal discharging between the address electrode  3  and the display electrode  13  occurs more frequently, and it more becomes difficult to precisely operate the PDP. 
   Turning now to  FIGS. 2 through 4 ,  FIG. 2  is a partial exploded perspective view of a PDP  200  according to an embodiment of the present invention, and  FIGS. 3 and 4  are partial plan and sectional views respectively of the PDP  200  illustrated in  FIG. 2 , illustrating the combined structure thereof. As illustrated in  FIGS. 2 through 4 , the PDP  200  includes first and second substrates  2  and  4  spaced apart from each other with a distance therebetween. Discharge cells  6 R,  6 G, and  6 B are arranged between the substrates  2  and  4  to emit visible rays with their independent discharge mechanisms, and display desired color images. 
   Specifically, address electrodes  8  are formed on the inner surface of the first substrate  2  in a direction (in the Y direction of the drawing), and a lower dielectric layer  10  is formed on the entire surface of the first substrate  2  covering the address electrodes  8 . Stripe-patterned barrier ribs  12  are formed on the lower dielectric layer  10  and are formed to be parallel to the address electrodes  8 . Red, green, and blue phosphor layers  14 R,  14 G, and  14 B are formed on the sidewalls of the barrier ribs  12  and on the top surface of the lower dielectric layer  10 . The respective barrier ribs  12  are disposed between neighboring address electrodes  8  with a certain height to allow a predetermined discharge space between the first and the second substrates  2  and  4 . 
   Discharge sustain electrodes  20  are formed on the inner surface of the second substrate  4  facing the first substrate  2 . Discharge sustain electrodes  20  are formed to run in an x-direction perpendicular to the address electrodes  8 . Discharge sustain electrodes  20  include a scanning electrode  16  and a display electrode  18 . A transparent upper dielectric layer  22  and an MgO protective layer  24  are formed on the entire inner surface of the second substrate  4  and cover the discharge sustain electrodes  20 . 
   In the embodiment of  FIGS. 2 through 4 , the scanning electrode  16  and the display electrode  18  each include a transparent portion or transparent electrode and a non-transparent and highly conductive portion or a bus electrode. The transparent portions  16   a  and  18   a  are formed respectively with metallic bus portions  16   b  and  18   b  formed at one side periphery (along one edge) of the transparent portions  16   a  and  18   a  to prevent a voltage drop in the transparent portions  16   a  and  18   a . The transparent portions  16   a  and  18   a  are preferably formed with indium tin oxide (ITO), and the bus portions  16   b  and  18   b  are preferably formed with a highly conductive metallic material such as silver. 
   The discharge space between the first and the second substrates  2  and  4  defined by the crossing or overlapping of the address electrodes  8  and the discharge sustain electrodes  20  forms a discharge cell, and the discharge cells  6 R,  6 G, and  6 B are internally filled with a discharge gas (a mixture gas of Ne—Xe). 
   In PDP  200 , the address electrodes  8  and the discharge sustain electrodes  20  are each specially designed to reduce mis-discharging. As illustrated in  FIG. 3 , the gap G 1  between two portions of the discharge sustain electrode  20  at the respective discharge cells  6 R,  6 G, and  6 B becomes the main discharge gap where the plasma discharge normally occurs. The gap G 2  between the discharge sustain electrode neighbors  20  at the neighboring discharge cells in the direction of the address electrode  8  (the y-direction) becomes the non-discharge gap where the plasma discharge does not ordinarily occur. That is, with the respective discharge cells  6 R,  6 G, and  6 B, the gap between the scanning electrode  16  and the display electrode  18  within a discharge cell functions as the main discharge gap G 1 , and the gap between the display electrode  18  (or the scanning electrode) at any one of the discharge cells and the scanning electrode  16  (or the display electrode) for a neighboring discharge cell in the direction of the address electrode  8  (y-direction) functions as the non-discharge gap G 2 . 
   With the PDP  200  according to the embodiment of the present invention, when the main discharge gap G 1  and the non-discharge gap G 2  are defined as above, the width D 1  of the address electrode  8  corresponding to (in the vicinity of) the main discharge gap G 1  is designed to be smaller than the width D 2  of the address electrode  8  corresponding to (in the vicinity of) the non-discharge gap G 2 . 
   Specifically, as illustrated in  FIG. 3 , when an imagined first horizontal line H 1  is drawn along the central axis of the scanning electrode  16 , and an imagined second horizontal line H 2  is drawn along the central axis of the display electrode  18 , the section between the first and the second horizontal lines H 1  and H 2  at the respective discharge cells  6 R,  6 G, and  6 B is defined as a main discharge section A, and the section between the first and the second horizontal lines H 1  and H 2  in two neighboring discharge cells in the direction of the address electrode  8  (y-direction) is defined as a non-discharge section B. 
   With the PDP  200  according to the embodiment of the present invention, when the main discharge section A centered around the main discharge gap G 1 , and the non-discharge section B around the non-discharge gap G 2  are defined in the above way, the width D 1  of the address electrode  8  corresponding to the main discharge section A is designed to be smaller than the width D 2  of the address electrode  8  corresponding to the non-discharge section B. That is, the address electrode  8  is structured such that the facing area (or overlapping area) between the address electrode  8  and the display electrode  18  is reduced by making the address electrode  8  narrower in this overlapping discharge region A. 
   With the above structure, when an address voltage Va is applied between the address electrode  8  and the scanning electrode  16 , the address discharge is made within the discharge cells. As a result, wall charges are generated over the lower dielectric layer  10  near the address electrode  8 , and over the upper dielectric layer  22  near the scanning electrode  16  and the display electrode  18 , thereby selecting the discharge cells to emit light. 
   Thereafter, when a sustain voltage Vs is applied between the scanning electrode  16  and the display electrode  18 , the accumulated wall charge near the scanning electrode  16  combines with the accumulated wall charges near the display electrode  18  to thus generate a plasma discharge, that is, the sustain discharge. At this time, vacuum ultraviolet rays are emitted from the excited atoms of Xe during the plasma discharge. The vacuum ultraviolet rays excite the phosphor layers to emit visible rays, and thus display color images. 
   With the PDP  200  according to the embodiment of the present invention, at portions where the address electrode  8  and display electrode  18  overlaps (i.e., within a discharge cell or main discharge section A), since the address electrodes  8  are narrower in the main discharge section A than outside this main discharge section A, the area of the address electrode  8  that faces (or overlaps) the display electrode  18  is reduced so that possible unnecessary discharging between the address electrode  8  and the display electrode  18  can be prevented. As a result, with the PDP  200  according to the embodiment of the present invention, the generation of wall charges due to the interactive interference between the address electrode  8  and the display electrode  18  within the discharge cells  6 R,  6 G, and  6 B is inhibited after the reset interval, thereby preventing the discharge cells  6 R,  6 G, and  6 B from being mis-discharged. 
   The width D 1  of the address electrode  8  corresponding to the main discharge section A is preferably designed based on the content of Xe in the discharge gas. That is, when the address electrode  8  and the display electrode  18  face (or overlap) each other, the higher the content of Xe in the discharge gas is, the more the mis-discharging occurs between the address electrode  8  and the display electrode  18 . Therefore, as the content of Xe in the discharge gas is increased, the facing area (or overlapping area) between the address electrode  8  and the display electrode  18  should be reduced to prevent the mis-discharging between these two electrodes. Thus, it is preferable to have the width D 1  of the address electrode  8  in main discharge section A to be most narrow for higher contents of Xe, and to allow D 1  to be a bit wider for lower contents of Xe. 
   With the PDP  200  according to the embodiment of the present invention, the discharge gas contains 5% or more of Xe, preferably 10˜30% of Xe, to enhance the light emission efficiency. Furthermore, the width D 1  of the address electrode  8  corresponding to the discharge section A is established to be 40˜140 μm, thus reducing the facing or overlap area between the address electrode  8  and the display electrode  18  and thus preventing the mis-discharge between the address electrode  8  and the display electrode  18 . In this case, the width D 2  of the address electrode  8  corresponding to the non-discharge section B is preferably designed to be about 180 μm. 
   Table 1 illustrates empirical measurement results related to the mis-discharging between the address electrode  8  and the display electrode  18  while varying the width D 1  of the address electrode  8  in the main discharge section A and while varying the content Xe in the discharge gas. In Table 1, ∘ indicates occurrence of mis-discharging for a particular width D 1  and a particular Xe content while an x indicates non-occurrence of mis-discharging for a particular width D 1  and a particular Xe content. The PDP used in Table 1 was a 42-inch ADS driving PDP (a PDP that abides by address, display-period separation driving method), the width of the display electrode of the PDP was 340 μm, and the voltage waveform was the same as that illustrated in  FIG. 5 . The driving voltages as a function of the Xe content are listed in Table 2. 
   
     
       
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
             
             
           
         
             
                 
               TABLE 1 
             
           
           
             
                 
                 
             
             
                 
               Content of Xe in 
                 
             
             
                 
               discharge gas (%) 
             
           
        
         
             
                 
               10 
               15 
               20 
               30 
             
             
                 
                 
             
           
        
         
             
                 
               Width D1 of 
               40 
               x 
               x 
               x 
               x 
             
             
                 
               address 
               60 
               x 
               x 
               x 
               x 
             
             
                 
               electrode 8 in 
               80 
               x 
               x 
               x 
               x 
             
             
                 
               the vicinity of 
               100 
               x 
               x 
               x 
               x 
             
             
                 
               main discharge 
               120 
               x 
               x 
               x 
               ∘ 
             
             
                 
               section A (μm) 
               140 
               x 
               ∘ 
               ∘ 
               ∘ 
             
             
                 
                 
               160 
               ∘ 
               ∘ 
               ∘ 
               ∘ 
             
             
                 
                 
               180 
               ∘ 
               ∘ 
               ∘ 
               ∘ 
             
             
                 
                 
             
           
        
       
     
   
   
     
       
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
             
             
           
         
             
                 
               TABLE 2 
             
           
           
             
                 
                 
             
             
                 
               Content of Xe in 
                 
             
             
                 
               discharge gas (%) 
             
           
        
         
             
                 
               10 
               15 
               20 
               30 
             
             
                 
                 
             
           
        
         
             
                 
               Driving 
               Vset 
               360 
               390 
               420 
               420 
             
             
                 
               voltage (V) 
               Ve 
               200 
               220 
               250 
               250 
             
             
                 
                 
               Vscan 
               80 
               100 
               120 
               120 
             
             
                 
                 
               Va 
               85 
               85 
               95 
               95 
             
             
                 
                 
               Vs 
               210 
               230 
               250 
               250 
             
             
                 
                 
             
           
        
       
     
   
   As illustrated by Tables 1 and 2 above, when the content of Xe in the discharge gas was 10˜30%, and the width D 1  of the address electrode  8  in the vicinity of the main discharge section A was 40˜140 μm, the light emission efficiency was enhanced while unnecessary discharging between the address electrode  8  and the display electrode  18  was inhibited, thus preventing the discharge cells  6 R,  6 G, and  6 B from being mis-discharged. 
   Turning now to  FIGS. 6 through 9 ,  FIGS. 6 through 9  illustrate additional structural features of a PDP that can be added to the PDP  200  of  FIGS. 2 through 4  and thus produce variants of PDP  200 . Turning now to  FIG. 6 ,  FIG. 6  illustrates a first variant in PDP  200  according to the present invention. With the basic structure related to the PDP according to the present invention, the width of a portion of the address electrode  8  corresponding to the non-discharge section B is reduced from D 2  to D 3 . That is, in this variant, the width D 3  of the address electrode  8  corresponding to the center of the non-discharge section B is smaller than the width D 2  of the address electrode  8  corresponding to remaining portions of the non-discharge section B in the PDP  600  of  FIG. 6 . For instance, the width D 3  of the address electrode  8  corresponding to the center of the non-discharge section B may be the same as the width D 1  of the address electrode  8  corresponding to the main discharge section A. Accordingly, with the variant of the PDP where the width of the address electrode  8  corresponding to a middle portion of the non-discharge section B is partially reduced, mis-discharging between the cells spaced from each other in the y-direction by non-discharge gap G 2  can be prevented. 
   Turning now to  FIG. 7 ,  FIG. 7  illustrates a second variant in PDP  200  according to the present invention. With the basic structure related to the PDP according to the embodiment of the present invention, the transparent portions or transparent electrodes  16   a  and  18   a  of the discharge sustain electrode  20  are formed as protrusion types such that they extend from the bus portions  16   b  and  18   b  toward a center of the respective discharge cells  6 R,  6 G, and  6 B, and a pair thereof face each other in the middle of the discharge cell and are separated from each other by main discharge gap G 1 . With the protrusion-type transparent portions  16   a  and  18   a  of PDP  700  of  FIG. 7 , the discharge cells  6 R,  6 G, and  6 B can be prevented from being mis-discharged in the direction of the discharge sustain electrode  20  (i.e., the x-direction). Thus, in the variant PDP  700  of  FIG. 7 , the transparent portions  16   a  and  18   a  protrude in the y-direction as individual tabs for each discharge cell instead of merely making the electrodes wider as in PDP  200 . By having the transparent portions  16   a  and  18   a  as tabs instead of a continuously wide electrode, mis-discharging between neighboring discharge cells in the x-direction is further prevented. 
   Turning now to  FIGS. 8 and 9 ,  FIGS. 8 and 9  illustrate a third variant of PDP  200  according to the present invention. PDP  800  of  FIGS. 8 and 9  differs from PDP  200  in that the barrier ribs  12 ′ are of a lattice or a matrix form instead of merely being of a stripe pattern. With the basic structure related to the PDP  800  according to the embodiment of the present invention, the barrier rib  12 ′ is lattice-shaped with a first barrier rib portion  12   a  proceeding in the direction parallel to the address electrodes  8  (y-direction), and a second barrier rib portion  12   b  proceeding perpendicular to the address electrodes  8  (in an x-direction). The lattice-shaped barrier rib  12 ′ partitions the respective discharge cells  6 R,  6 G, and  6 B separately, thereby further preventing the mis-discharge between neighboring discharge cells  6 R,  6 G, and  6 B. 
   As described above, with the inventive PDP, unnecessary discharging between the address electrode and the display electrode is inhibited to thereby prevent the discharge cells from being mis-discharged. Furthermore, the discharge gas contains 5% or more of Xe, preferably 10-30% of Xe, thereby heightening the intensity of the vacuum ultraviolet rays, and enhancing the light emission efficiency. 
   Although embodiments of the present invention have been described in detail hereinabove in connection with exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary is intended to cover various and/or equivalent arrangements included within the spirit and scope of the present invention, as defined in the appended claims. It is also to be appreciated that the variants of  FIGS. 6 through 9  can be mixed together in any combination and still be within the scope of the present invention.