Abstract:
There is provided a plasma display. The plasma display includes a pixel that, in turn, includes (a) a region for hosting a discharge of a gas, (b) a column electrode, (c) a row electrode, perpendicular to the column electrode, for providing a voltage to initiate the discharge, wherein the row electrode has a first protrusion and a second protrusion, and (d) a gap, between the first and second protrusions, having a width that separates the first protrusion from the second protrusion, wherein the gap is situated in the region.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present disclosure relates to a pixel of a plasma display, wherein the pixel is configured to provide a plurality of discharge columns. 
         [0003]    2. Description of the Related Art 
         [0004]    A plasma display includes a front plate and a rear plate sealed together and having a space therebetween filled with a dischargeable gas. The front plate includes horizontal rows of electrodes, each row being configured with a sustain electrode in parallel with a scan electrode. The scan electrodes and the sustain electrodes are covered by a dielectric layer and a magnesium oxide (MgO) layer. The rear plate supports vertical barrier ribs and plural vertical column conductors. In a color display, individual column electrodes are covered with red, green, or blue (RGB) phosphors. A pixel is defined as a region proximate to an intersection of (i) a scan electrode and a sustain electrode, and (ii) three column conductors, one for each color. In a monochrome display, a single column conductor is used for each pixel, and a phosphor combination is used to achieve the monochromatic color. Visible light is emitted by the phosphors following UV excitation, produced when a voltage of a sufficient magnitude is applied across a volume of the gas to cause the gas to discharge. When the gas discharges, the atoms of the gas are excited, when the atoms relax, the atoms emit UV photons, which, in turn, excite the phosphor. 
         [0005]    A discharge gap is a region of space between a scan electrode and a sustain electrode within which the discharge occurs. A positively charged electrode serves as an anode and a negatively charged electrode serves as a cathode. When a sufficient voltage is applied across the discharge gap, the gas will break down and form a discharge plasma. The discharge plasma has two distinct regions, namely a positive column and a negative glow. The positive column is predominantly composed of fast moving electrons seeking a positive charge on the surface of the anode electrode. Conversely, the negative glow contains slow moving ions drifting toward and across the negatively charged cathode electrode. The duration of the discharge is limited by the amount of charge on the dielectric surfaces of the electrodes. 
         [0006]    Each discharge yields a certain level of brightness, and therefore a number of discharges in a predetermined period of time is chosen to meet an overall brightness requirement for an image being displayed. Light output from each discharge site is emitted at the discharge gap and above and below the electrodes that form the discharge gap. The dimension of space between adjacent electrodes, and the overall width of the electrodes, influence the pixel&#39;s discharge capacitance, which in turn influences discharge power and therefore brightness. There is a trade-off between electrode width and brightness because the electrodes tend to shade the emitted light. 
         [0007]    In a traditional electrode topology, the plasma discharge funnels into a narrow conductive filament where the discharge is very intense. This physically narrow intense discharge causes erosion of the MgO surface and can damage the phosphor over the life of the plasma display. 
         [0008]    There is a need in the art to improve the lifetime and luminous efficiency of plasma discharge devices, and there is a need for electrode topologies to improve efficiency where light blockage is reduced, and discharge power is reduced. 
       SUMMARY OF THE INVENTION 
       [0009]    There is provided a plasma display. The plasma display includes a pixel that, in turn, includes (a) a region for hosting a discharge of a gas, (b) an electrode for providing a voltage to initiate the discharge, wherein the electrode has a first protrusion and a second protrusion, and (c) a gap, between the first and second protrusions, having a width that separates the first protrusion from the second protrusion, wherein the gap is situated in the region. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is an illustration of a pixel in a plasma display panel. 
           [0011]      FIG. 2A  is an illustration of a subpixel of  FIG. 1 , showing a formation of a discharge. 
           [0012]      FIG. 2B  is a photograph of a discharge of the subpixel of  FIG. 2A . 
           [0013]      FIG. 3  is an illustration of another configuration of a pixel. 
           [0014]      FIG. 4  is an illustration of a subpixel of  FIG. 3 , showing a formation of a discharge. 
           [0015]      FIGS. 5A ,  5 B and  5 C are illustrations of other configurations of subpixels. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0016]      FIG. 1  is an illustration of a pixel  100  in a plasma display. The plasma display includes electrodes  105  and  130 , barrier ribs  150 ,  151 ,  152  and  153 , a red column electrode  145 R, a green column electrode  145 G, and a blue column electrode  145 B. A discharge gap  155  is situated between electrodes  105  and  130 . 
         [0017]    Pixel  100  is configured to include a red subpixel, a green subpixel, and a blue subpixel. The red subpixel is a region in a vicinity of electrode  105 , electrode  130 , and red column electrode  145 R, and is bounded on its sides by barrier ribs  150  and  151 . The green subpixel is a region in a vicinity of electrode  105 , electrode  130 , and green column electrode  145 G, and is bounded on its sides by barrier ribs  151  and  152 . The blue subpixel is a region in a vicinity of electrode  105 , electrode  130 , and blue column electrode  145 B, and is bounded on its sides by barrier ribs  152  and  153 . The blue subpixel is designated in  FIG. 1  as a subpixel  110 . 
         [0018]    The terms “pixel” and “subpixel” are used herein only to indicate a hierarchy in which the subpixel is a component of the pixel. Generally, any individually addressable picture element can be referred to as a pixel. The red subpixel, the green subpixel and the blue subpixel are individually addressable, and therefore could be referred to as a red pixel, a green pixel and a blue pixel, respectively, and subpixel  110 , in spite of being designated as a “subpixel”, is a form of a pixel. 
         [0019]    With appropriate voltages on electrodes  105 , electrode  130 , and blue column electrode  145 B, there will be a discharge of a gas in the vicinity of subpixel  110 . The region bounded by electrode  105 , electrode  130 , blue column electrode  145 B and barrier ribs  152  and  153 , is for hosting the discharge. For subpixel  110 , electrode  105  is configured to include protrusions  125 L and  125 R. A gap  120  between protrusion  125 L and protrusion  125 R has a width that separates protrusion  125 L from protrusion  125 R. Gap  120  is situated in the region of subpixel  110  that hosts the discharge of the gas, and is approximately centered between barrier ribs  152  and  153 , which form the side boundaries of subpixel  110 . 
         [0020]      FIG. 2A  is an illustration of subpixel  110 , showing a formation of a discharge. Assume that for the discharge, electrode  105  has a negative charge with respect to electrode  130 . The discharge is initially formed in discharge gap  155 , and has a negative glow portion that spreads from discharge gap  155  to electrode  105 , as ions generated in the discharge drift toward electrode  105 . Conversely, and much more rapidly, a positive column, with electron flow, reaches from electrode  105  across discharge gap  155  to electrode  130 . The positive column initially forms as a single positive column. 
         [0021]    Protrusions  125 L and  125 R provide a low breakdown voltage path between electrodes  105  and  130  since they effectively provide a shorter discharge gap between electrodes  105  and  130 . Protrusions  125 L and  125 R provide little charge to maintain the discharge since their area is small compared to the electrodes  105  and  130 , however, electrodes  105  and  130  provide ample charge to supply the discharge. Thus, the single positive column spreads across the discharge gap  155 , aided by protrusions  125 L and  125 R, extends between electrodes  105  and  130 , and separates into two columns, namely a column  205  and a column  210 . Column  205  is on the left side of gap  120 , and column  210  is on the right side of gap  120 . 
         [0022]    The greater the width of gap  120 , the greater is the propensity for the initial positive column to separate into separate columns, i.e., columns  205  and  210 . In an exemplary implementation of subpixel  110 , gap  120  has a width of about 80 microns to about 100 microns. 
         [0023]    In subpixel  110 , protrusions  125 L and  125 R are horizontally situated. A portion of column  205  forms above protrusion  125 L, i.e., between protrusion  125 L and electrode  105 , and another portion of column  205  forms below protrusion  125 L, i.e., between portion  125 L and electrode  130 . Similarly, a portion of column  210  forms above protrusion  125 R, and a portion of column  210  forms below protrusion  125 R. 
         [0024]    Although not shown in  FIG. 2A , column  205  also includes a portion behind protrusion  125 L, and column  210  includes a portion behind protrusion  125 R. If protrusions  125 L and  125 R are neither translucent nor transparent, then the portions of columns  205  and  210  behind protrusions  125 L and  125 R will not be visible. However, if protrusions  125 L and  125 R are configured of a translucent or transparent material, for example tin oxide or indium tin oxide, then the portions of columns  205  and  210  behind protrusions  125 L and  125 R will be visible. 
         [0025]      FIG. 2B  is a photograph of a discharge of subpixel  110 . Columns  205  and  210  include striations, i.e., bright lines, which are characteristic of the positive column portion of a discharge. Also, the intensity of the discharge is greater in the vicinity of electrode  105  than in the vicinity of electrode  130  because the negative glow, which drifts from discharge gap  155  toward electrode  105 , dissipates more power than the positive column. 
         [0026]      FIG. 3  is an illustration of another configuration of a pixel, i.e., a pixel  300 , that produces a plurality of discharge columns. Pixel  300  includes a subpixel  310  having a region for hosting a discharge, bounded by an electrode  305 , an electrode  330 , and barrier ribs  352  and  353 . Electrode  305  includes a protrusion  325 L and a protrusion  325 R, with a gap  320  therebetween. 
         [0027]      FIG. 4  is an illustration of subpixel  310 , showing a formation of a discharge. The discharge forms as a column  405  on one side of gap  320 , and a column  410  on the other side of gap  320 . 
         [0028]    Protrusions  325 L and  325 R, unlike protrusions  125 L and  125 R, are not horizontally situated, and so, much of column  405  is located behind protrusion  325 L, and much of column  410  is located behind protrusion  325 R. To maximize the viewable areas of columns  405  and  410 , protrusions  325 L and  325 R are configured of either a translucent or transparent material. 
         [0029]      FIGS. 5A ,  5 B and  5 C are illustrations of other configurations of subpixels that produce a plurality of discharge columns. 
         [0030]      FIG. 5A  shows a subpixel  500 , configured with electrodes  502  and  512 , and bounded by barrier ribs  504  and  506 . Electrode  502  includes protrusions  508  and  510 , but electrode  512  does not have any protrusions. Thus, opposing electrodes need not be symmetrically configured, and it is not necessary for more than one electrode to have protrusions. 
         [0031]      FIG. 5B  shows a subpixel  520 , configured with electrodes  522  and  538 , and bounded by barrier ribs  524  and  526 . Electrode  522  includes five protrusions, namely protrusions  528 ,  530 ,  532 ,  534  and  536 , distributed along electrode  522  in a horizontal manner. A discharge column will form adjacent to each of protrusions  528 ,  530 ,  532 ,  534  and  536 , and so, subpixel  520  will have five discharge columns. As such, subpixel  520  can have a greater horizontal dimension than a subpixel that has no protrusions. Generally, a subpixel can include any desired number of protrusions in a horizontal arrangement to extend the horizontal dimension of the subpixel to any desired width. 
         [0032]      FIG. 5C  shows a subpixel  540 , configured with electrodes  542  and  564 , and bounded by barrier ribs  544  and  546 . Electrode  542  includes protrusions having horizontal members  548 ,  550 ,  552  and  554 . Electrode  564  includes protrusions having horizontal members  556 ,  558 ,  560  and  562 . Horizontal members  548 ,  552 ,  556  and  560  are situated vertically with respect to one another, and horizontal members  550 ,  554 ,  558  and  562  are situated vertically with respect to one another. A first discharge column will form between electrodes adjacent to horizontal members  548 ,  552 ,  556  and  560 , and a second discharge column will form adjacent to horizontal members  550 ,  554 ,  558  and  562 . As such, subpixel  540  can have a greater vertical dimension than a subpixel that has no protrusions. Generally, a subpixel can include any desired number of vertically situated horizontal protrusions to extend the vertical dimension of the subpixel to any desired height. 
         [0033]    The techniques described herein are exemplary, and should not be construed as implying any particular limitation on the present invention. It should be understood that various alternatives, combinations and modifications could be devised by those skilled in the art. The present invention is intended to embrace all such alternatives, modifications and variances that fall within the scope of the appended claims.