Abstract:
A Plasma Display Panel (PDP) includes: front and rear substrates facing each other; address electrodes arranged on the rear substrate; barrier ribs arranged between the front and rear substrate to define first, second, and third color discharge cells, the discharge cells being filled with a discharge gas; first, second, and third color layers adapted to be excited by the discharge gas and to emit light; and display electrodes arranged on the front substrate, the display electrodes including non-transparent protrusion electrodes protruding inward from edges of the discharge cells. The non-transparent protrusion electrodes of at least two of the first, second, and third color discharge cells have different areas.

Description:
CLAIM OF PRIORITY  
       [0001]     This application makes reference to, incorporates the same herein, 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 28 May 2004 and there duly assigned Serial No. 10-2004-0038172.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a Plasma Display Panel (PDP), and more particularly, to a PDP using non-transparent protrusion electrodes protruding inward from edges of discharge cells to improve color temperature and Bright Room Contrast Ratio (BRCR).  
         [0004]     2. Description of the Related Art  
         [0005]     A Plasma Display Panel (PDP) is an image forming apparatus using a plasma discharge to excite phosphor layers. A predetermined voltage is supplied between two electrodes arranged in a discharge space of the PDP to generate the plasma discharge. Vacuum Ultraviolet light (VUV) generated by the plasma discharge excites the phosphor layers. Visible light emitted from the phosphor layers are used to form an image. The PDPs are classified into AC, DC, and hybrid PDPs.  
         [0006]     The AC PDP includes a pair of front and rear substrates facing each other. Address electrodes are arranged on the rear substrate. A dielectric layer is arranged to cover the address electrodes. A plurality of barrier ribs are arranged on the dielectric layer to partition the discharge space into a plurality of discharge cells. The barrier ribs maintain a discharge distance and prevent electrical and optical crosstalk between the discharge cells.  
         [0007]     In addition, display electrodes including pairs of X and Y electrodes are arranged on the front substrate in a direction intersecting the address electrodes.  
         [0008]     The X and Y electrodes are made of Indium Tin Oxide (ITO), which is a transparent material. In order to compensate for the conductivity of the ITO, bus electrodes are made of a metallic material.  
         [0009]     Recently, in order to easily generate the plasma discharge, the ITO electrode has been designed to protrude inward from an edge of the discharge cell. In addition, in order to improve Bright Room Contrast Ratio (BRCR) by reducing external light reflection, the metal bus electrode, in a fashion similar to the ITO electrode, has been designed to protrude inward from an edge of the discharge cell.  
         [0010]     On the other hand, since Blue (B) phosphor layers emits a lower intensity of light than Red (R) and Green (G) phosphor layers, the B phosphor layers have a lower color temperature.  
         [0011]     Therefore, conventionally, a variety of approaches for compensating for the color temperature have been proposed. One approach is to lower peak values of the R and G analog image signals by performing a gamma correction on the R and G analog image signals excluding the B analog image signal (which has a relatively low brightness) and, after that, to perform digitalization, so that the number of sustain pulses for generating the highest brightness of R and G colors can be smaller than the number of sustain pulses for generating the highest brightness of B to improve the color temperature. Another approach is to increase the area of B discharge cells and decrease the area of R and G discharge cells, so that the color temperature can be improved.  
         [0012]     All of the 255 sustain pulses need to be used to express the highest brightness of R and G colors. Therefore, in case of expressing a fading-in or fading-out image, the former approach using the gamma correction has a problem in that a step phenomenon occurs in R and G colors.  
         [0013]     On the other hand, the latter approach using asymmetrical discharge cells has a problem in that discharge unevenness occurs due to differences between the areas of the discharge cells for different colors. These approaches also have a problem of mis-discharge caused by the discharge unevenness and decrease in a voltage margin for stable driving. In addition, since individual masks for printing the R, G, and B phosphor layers are needed, the approach has increased production costs and decreased visual resolution.  
       SUMMARY OF THE INVENTION  
       [0014]     An object of the present invention is to provide a plasma display panel using non-transparent protrusion electrodes protruding inward from edges of discharge cells to improve color temperature and Bright Room Contrast Ratio (BRCR).  
         [0015]     In order to achieve the object, according to an aspect of the present invention, a Plasma Display Panel (PDP) there is provided comprising: front and rear substrates facing each other; address electrodes arranged on the rear substrate; barrier ribs arranged between the front and rear substrate to define first, second, and third color discharge cells, the discharge cells being filled with a discharge gas; first, second, and third color phosphor layers adapted to be excited by the discharge gas and to emit light; and display electrodes arranged on the front substrate, the display electrodes including non-transparent protrusion electrodes protruding inward from edges of the discharge cells; wherein the non-transparent protrusion electrodes of at least two of the first, second, and third color discharge cells have different areas.  
         [0016]     The area of the non-transparent protrusion electrode in the third color discharge cell is preferably smaller than the areas of the non-transparent protrusion electrodes in the first and second color discharge cells.  
         [0017]     The non-transparent protrusion electrodes preferably comprise first electrodes protruding inward from the edges of the discharge cells.  
         [0018]     The first electrodes preferably extend in a direction parallel to the address electrodes.  
         [0019]     The first electrodes alternatively preferably extend in a direction at a predetermined angle with respect to the address electrodes.  
         [0020]     The non-transparent protrusion electrodes preferably further comprise second electrodes arranged at ends of the first electrodes.  
         [0021]     The first electrodes preferably extend in a direction parallel to the address electrodes; and the second electrodes preferably extend in a direction perpendicular to the first electrodes.  
         [0022]     The first electrodes alternatively preferably extend in a direction at a predetermined angle with respect to the address electrodes, and the second electrodes preferably extend in a direction perpendicular to the address electrodes.  
         [0023]     Widths of the second electrodes are preferably equal to widths of the first electrodes.  
         [0024]     Widths of the second electrodes are alternatively preferably greater than widths of the first electrodes.  
         [0025]     The display electrodes preferably further comprise transparent electrodes electrically connected to the non-transparent protrusion electrodes.  
         [0026]     The transparent electrodes are preferably arranged within the discharge cells.  
         [0027]     The display electrodes preferably have a symmetrical structure.  
         [0028]     The display electrodes alternatively preferably have an asymmetrical structure.  
         [0029]     The first, second, and third colors preferably comprise red, green and blue. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0030]     A more complete appreciation of the present invention, and many of the attendant advantages thereof, will be readily apparent as the present invention becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:  
         [0031]      FIG. 1  is an exploded perspective view of a plasma display apparatus according to an embodiment of the present invention;  
         [0032]      FIG. 2  is an exploded perspective view of a Plasma Display Panel (PDP) according to an embodiment of the present invention;  
         [0033]      FIG. 3  is an schematic view of main components of the PDP of  FIG. 2 ;  
         [0034]      FIG. 4  is a schematic view of main components of a PDP according to another embodiment of the present invention; and  
         [0035]      FIGS. 5A and 5B  are schematic views of main components of a PDP according to still another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0036]     Embodiments of the present invention are described below in detail with reference to the accompanying drawings.  
         [0037]      FIG. 1  is an exploded perspective view of a plasma display apparatus according to an embodiment of the present invention.  
         [0038]     A PDP  10  comprises front and rear substrates  10   a  and  10   b  which are integrally joined with a sealing member such as a frit. A plurality of discharge cells are provided in the PDP. A plasma discharge is generated in the discharge cells. Vacuum Ultraviolet (VUV) light generated by the plasma discharge excites phosphor layers. Visible light emitted by the phosphor layers are used to form an image.  
         [0039]     The plasma display apparatus having the PDP  10  includes: a chassis base  14  for supporting the rear substrate of the PDP  10  and mounting a plurality of printed circuit board assemblies  12 ; a front cabinet  16  arranged in front of the PDP  10 ; and a back cover  18  arranged behind the chassis base  14  to surround the PDP  10  and the chassis base  14 . The front cabinet  16  and the back cover  18  are integrally assembled to cover the plasma display apparatus.  
         [0040]     More specifically, a variety of printed circuit board assemblies  12  are mounted on the rear surface of the chassis base  14  facing the back cover  18 . The printed circuit board assemblies  12  include a power supply board, an image processing board, an address buffer board, and X and Y boards. In order to dissipate heat generated by the PDP  10  and the circuit board assemblies  12 , the chassis base  14  is made of an effective heat-radiating material or formed as an effective heat-radiating structure.  
         [0041]     A conductive film filter  16 a for preventing an electrostatic phenomenon is provided on the front cabinet  16 . The conductive film filter  16   a  is in contact with the front substrate  10   a . A plurality of air vent holes  18   a  are provided in the back cover  18  to release heat generated by the PDP  10  of the plasma display apparatus.  
         [0042]     The plasma display apparatus includes heat-conductive media  20  for transferring the heat generated by the PDP  10 . The heat-conductive media  20  is arranged between the PDP  10  and the chassis base  14 . In addition, an adhesive member  22 , such as double-sided adhesive tape, is arranged along an edge of the rear substrate  10   b  of the PDP  10  to affix the PDP  10  to the chassis base  14 . In addition to affixing the PDP  10  to the chassis base  14 , the adhesive member  22  maintains a distance between the PDP  10  and the chassis base  14  and absorbs external impact.  
         [0043]     An embodiment of the present invention is described below with reference to FIGS.  2  and  3 .  
         [0044]      FIG. 2  is an exploded perspective view of a PDP according to the embodiment of the present invention.  FIG. 3  is a schematic view of main components of the PDP of  FIG. 2 .  
         [0045]     Address electrodes A are arranged on an inner surface of the rear substrate  10   b . A dielectric layer  24  covers the address electrodes A on the inner surface of the rear substrate  10   b . Barrier ribs  26  are arranged on the dielectric layer  24  in stripes in the direction parallel to the address electrodes A. Red, Green and Blue phosphor layers R, G, and B are coated on bottoms (dielectric layer  24 ) and walls (barrier ribs  26 ) of the discharge cells partitioned by the barrier ribs  26 . Hereinafter, the discharge cells coated with the phosphor layers R, G, and B will be referred to as red, green, and blue discharge cells  28 R,  28 G, and  28 B, respectively.  
         [0046]     Display electrodes D are arranged on an inner surface of the front substrate  10   a  in a direction intersecting the address electrodes A. In this embodiment, each of the display electrodes D comprises a pair of bus electrodes  30   a  and  30   b , a pair of transparent electrodes  32   a  and  32   b  electrically connected to the bus electrodes  30   a  and  30   b , and a pair of non-transparent protrusion electrodes  34   a  and  34   b  electrically connected to the transparent electrodes  32   a  and  32   b . The pair of transparent electrodes  32   a  and  32   b  protrude inward from edges of the discharge cells  28 R,  28 G, and  28 B in order to easily generate discharges between the electrodes.  
         [0047]     In a fashion similar to the transparent electrodes  32   a  and  32   b , the non-transparent protrusion electrodes  34   a  and  34   b  protrude inward from edges of the discharge cells  28 R,  28 G, and  28 B in order to prevent a decrease in the BRCR due to reflection of external light incident to the front substrate  10   a.    
         [0048]     In addition, the non-transparent protrusion electrodes  34   a  and  34   b  compensate the color temperature of the PDP. In order to compensate the color temperature, the non-transparent protrusion electrodes  34   a  and  34   b  have different areas according to the colors of the discharge cells  28 R,  28 G, and  28 B.  
         [0049]     In general, the R, G, and B phosphor layers coated in the discharge cells  28 R,  28 G, and  28 B emit light of different brightnesses. The brightness of the B phosphor layer is lower than that of the G phosphor layer.  
         [0050]     When the discharge cells  28 R,  28 G, and  28 B have the same size, in order to compensate the color temperature, the brightness of the discharge cells  28 G and  28 B must be adjusted to suitable levels. Therefore, in this embodiment, the area of the non-transparent protrusion electrodes  34   a  and  34   b  in the discharge cell  28 G is larger than the area of the non-transparent protrusion electrodes  34   a  and  34   b  in the discharge cell  28 B. The areas of the non-transparent protrusion electrodes  34   a  and  34   b  in the discharges cells can be adjusted by changing the widths of the electrodes.  
         [0051]     In this embodiment, the non-transparent protrusion electrodes  34   a  and  34   b  comprise first electrodes  34   a′  and  34   b′  protruding inward from edges of the discharge cells  28 R,  28 G, and  28 B, and second electrodes  34   a″  and  34   b″  arranged at ends of the first electrodes  34   a′  and  34   b′ . The first electrodes  34   a′  and  34   b′  extend in the direction (Y direction in the figure) parallel to the address electrodes A. The second electrodes  34   a″  and  34   b″  extend in the direction (X direction in the figure) perpendicular to the first electrodes  34   a′  and  34   b′.    
         [0052]     The shapes and directions of the first and second electrodes are not limited to those illustrated herein, but rather various modifications thereof are possible.  
         [0053]     In addition, the widths of the second electrodes  34   a″  and  34   b″  can be equal to or greater than those of the first electrodes  34   a′  and  34   b′.    
         [0054]     The transparent electrodes  32   a  and  32   b  are not essential components and can be selectively removed if necessary.  
         [0055]     Although the display electrodes D are symmetric structures in this embodiment, the display electrodes D can be asymmetric structures. For example, only one of the X and Y electrodes can be a non-transparent electrode. In addition, although both the X and Y electrodes can be non-transparent electrodes, it is not necessary for the non-transparent electrodes to have the same shape.  
         [0056]     Accordingly, in the PDP having the non-transparent protrusion electrodes  34   a  and  34   b , a decrease in the BRCR due to the reflection of external light can be prevented by the non-transparent protrusion electrodes  34   a  and  34   b . In addition, since the areas of the non-transparent protrusion electrodes  34   a  and  34   b  in the green discharge cell  28 G are larger than the areas of the non-transparent protrusion electrodes  34   a  and  34   b  in the blue discharge cell  28 B, the color temperature of the PDP can be compensated by adjusting the areas of the non-transparent protrusion electrodes.  
         [0057]      FIG. 4  is a schematic view of main components of a PDP according to another embodiment of the present invention. In the description below, the same components as those of the embodiment of  FIGS. 2 and 3  are denoted by the same reference numerals.  
         [0058]     This embodiment relates to a PDP with a delta pixel arrangement. In the PDP, bus electrodes  40   a  and  40   b  are arranged along barrier ribs  26 . One of the bus electrodes  40   a  and  40   b  is used as a common electrode.  
         [0059]     In each of the discharge cells  28 R,  28 G, and  28 B, a pair of non-transparent protrusion electrodes  44   a  and  44   b  are arranged to protrude and face each other. The non-transparent protrusion electrodes  44   a  and  44   b  comprise first electrodes  44   a″  and  44   b″  in a direction at a predetermined angle to the Y axis direction parallel to address electrodes and second electrodes  44   a″  and  44   b″  in the X axis direction perpendicular to the Y axis direction.  
         [0060]     Although the display electrodes D are symmetric structures in the embodiment, the display electrodes D can be asymmetric structures.  
         [0061]      FIGS. 5A and 5B  are schematic views of main components of a PDP according to still another embodiment of the present invention. In this embodiment, the display electrodes D are asymmetric structures.  
         [0062]     In a fashion similar to the PDP of  FIG. 4 , in the PDP according to this embodiment, one of bus electrodes  50   a  and  50   b  ( 60   a  and  60   b ) is used as a common electrode. Only one of the bus electrodes  50   a  and  50   b  ( 60   a  and  60   b ) is a non-transparent protrusion electrode.  
         [0063]     The non-transparent protrusion electrode  54  of the bus electrode  50   a  includes only the first electrode  54   a′  in the PDP of  FIG. 5A . On the other hand, in a fashion similar to the PDP of  FIGS. 2 and 3 , the non-transparent protrusion electrode includes the first and second electrodes  64   a′  and  64   b′  in the PDP of  FIG. 5B .  
         [0064]     According to a PDP in accordance with an embodiment of the present invention, since the reflection of external light is reduced by the non-transparent protrusion electrodes protruding inward from the edges of the discharge cells, it is possible to improve the BRCR. In addition, since the color temperature can be compensated, it is possible to solve conventional problems occurring in compensating the temperature by performing a gamma correction and using uneven barrier ribs.  
         [0065]     Although not shown in the drawings, a PDP according to the present invention can be constructed with various shapes of barrier ribs and other components. Therefore, any PDPs having non-transparent protrusion electrodes protruding inward from edges from discharge cells with different areas according to the colors of the discharge cells will be construed as being included within the scope of the present invention.  
         [0066]     While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various modifications in form and detail can be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.