Abstract:
A plasma display panel (PDP) having improved light emission efficiency by minimizing blockage of emitted visible light rays includes: a first substrate and a second substrate arranged opposite to each other; a plurality of barrier ribs arranged between the first and second substrates to define two sides of closed discharge cells; first electrodes and second electrodes arranged to extend in a direction intersecting the barrier ribs to define two other sides of the closed discharge cells and alternately arranged between the discharge cells defined consecutively; phosphor layers each arranged in the discharge cells partitioned by the barrier ribs and the first and second electrodes; address electrodes arranged on the second substrate; and third electrodes arranged on the first substrate to extend in a direction intersecting the address electrodes.

Description:
CLAIM OF PRIORITY 
   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 30 Jun. 2004 and there duly assigned Ser. No. 10-2004-0050879. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a Plasma Display Panel (PDP) and, more particularly, to a PDP having improved light emission efficiency. 
   2. Description of the Related Art 
   In general, a PDP is a light-emitting device for displaying an image using a gas discharge. The PDP provides excellent display capabilities in terms of display capacity, brightness, contrast, image retention, and viewing angle, such that it is becoming popular as a substitute for a CRT. A DC or AC voltage is supplied to electrodes to generate a gas discharge between the electrodes to emit ultraviolet (UV) light rays, and the UV light rays excite phosphor materials to generate visible light rays. 
   An AC PDP includes front and rear substrates which are bonded together to form an integrated body and are separated from each other by barrier ribs interposed therebetween. The front substrate includes X-electrodes and Y-electrodes which are sustain discharge electrodes. The rear substrate includes address electrodes. The barrier ribs have a phosphor layer formed thereon. Discharge cells partitioned by the barrier ribs disposed between the two substrates are filled with an inert gas such as Ne—Xe. 
   When an addressing voltage and a scan pulse are supplied to the address electrode and the Y-electrode, respectively, an address discharge occurs between the two electrodes so that a discharge cell is selected. Wall charges are formed within the selected discharge cell. 
   Subsequently, when a sustain discharge voltage is supplied to the X- and Y-electrodes, electrons and ions formed on the X- and Y-electrodes migrate between the X- and Y-electrodes. The sustain discharge voltage is added to a wall voltage formed by the wall charge to exceed a discharge initiation voltage. As a result, a sustain discharge occurs in the discharge cell. 
   During a sustain discharge period, UV light rays impinge on a phosphor layer in the discharge cell to create visible light rays, whereby each pixel formed in the discharge cell forms an image. 
   That is, the PDP is a three-electrode PDP where X- and Y-electrodes are provided on the front substrates of the discharge cell and an address electrode is provided on the middle of the rear substrate of the discharge cell intersecting the X- and Y-electrodes. 
   Accordingly, the three-electrode PDP has a poor light-emitting efficiency since the distance between the X- and Y-electrodes is kept short. Furthermore, since the X- and Y-electrodes are provided on the front substrate, a surface discharge is difficult and visible light rays emitted from the discharge cells are blocked, thereby decreasing the light emission efficiency. 
   SUMMARY OF THE INVENTION 
   The present invention provides a Plasma Display Panel (PDP) capable of facilitating a discharge and improving the light emission efficiency by minimizing the blockage of emitted visible light rays. 
   In accordance with an aspect of the present invention, a Plasma Display Panel (PDP) is provided comprising: a first substrate and a second substrate arranged opposite to each other; a plurality of barrier ribs arranged between the first and second substrates to define two sides of closed discharge cells; first electrodes and second electrodes arranged to extend in a direction intersecting the barrier ribs to define two other sides of each of the discharge cells and alternately arranged between the discharge cells consecutively defined; phosphor layers each arranged in the discharge cells defined by the barrier ribs and the first and second electrodes; address electrodes arranged on the second substrate; and third electrodes arranged on the first substrate to extend in a direction intersecting the address electrodes. 
   The discharge cells are preferably rectangular in shape. 
   The first and second electrodes are preferably arranged to act on all of the discharge cells adjacent to the address electrode in the extending direction thereof. 
   The first, second and third electrodes are preferably arranged between the first and second substrates in a repeating order of first electrode—third electrode—second electrode—third electrode—first electrode. 
   The first and second electrodes are preferably strip shaped, and are preferably opposite to each other on two sides of each of the discharge cells in the extending direction of the address electrodes. 
   The first and second electrodes preferably comprise a metallic material having an excellent electrical conductivity. 
   The first and second electrodes preferably have a dielectric layer on both sides of the address electrodes in the extending direction of the address electrodes. 
   The dielectric layer is preferably covered with a phosphor layer. 
   The third electrode preferably includes a transparent electrode arranged on the first substrate between the first and second electrodes and extending parallel to the first and second electrodes, and a bus electrode arranged on the transparent electrode and extending in the same direction as the transparent electrode. 
   The bus electrode preferably has a width narrower than that of the transparent electrode. 
   The third electrode is preferably covered with a dielectric layer and a MgO protective film. 
   The discharge cells are preferably rectangular in shape; the first electrodes are preferably separately arranged on both sides of a first barrier rib interposed therebetween; and the second electrodes are preferably separately arranged on both sides of a second barrier rib interposed therebetween. 
   The first electrodes are preferably arranged between the first and second substrates to have the same height as the first barrier rib; and the second electrodes are preferably arranged between the first and second substrates to have the same height as the second barrier rib. 
   The first electrodes and second electrodes are preferably covered with a dielectric layer. 
   The first electrodes are preferably arranged between the first and second substrates to be lower in height than the first barrier rib, and the second electrodes are preferably arranged between the first and second substrates to be lower in height than the second barrier rib. 
   The first and second electrodes are preferably arranged in the center of the discharge cells between the first and second substrates in the height direction of the discharge cells. 
   The first electrodes lower in height than the first barrier rib and a portion of the first barrier rib not covered by the first electrodes and the second electrodes lower in height than the second barrier rib and a portion of the second barrier rib not covered by the second electrodes are preferably covered with a dielectric layer. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     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: 
       FIG. 1  is a partially exploded perspective view of a PDP in accordance with a first embodiment of the present invention; 
       FIG. 2  is a top plan view of  FIG. 1 ; 
       FIG. 3  is a cross-sectional view taken along the line III-III of  FIG. 1 ; 
       FIG. 4  is a cross-sectional view of a PDP in accordance with a second embodiment of the present invention; and 
       FIG. 5  is a cross-sectional view of a PDP in accordance with a third embodiment of the present invention. 
   

   DESCRIPTION OF THE INVENTION 
   Hereinafter, exemplary embodiments of the present invention are described below in more detail with reference to the accompanying drawings where like reference numerals refer to like elements. 
     FIG. 1  is a partially exploded perspective view of a PDP in accordance with a first embodiment of the present invention. 
   Referring to  FIG. 1 , a PDP according to the first embodiment includes a first substrate  1  (hereinafter referred to as “front substrate”) and a second substrate  3  (hereinafter referred to as “rear substrate”) which are bonded together to form an integrated body, opposed to and separated from each other by a predetermined distance. 
   A plurality of barrier ribs  5 , and first electrodes  7  and second electrodes  9 , which are alternately arranged in a direction intersecting the barrier ribs  5 , are provided between the front substrate  1  and the rear substrate  3 , thereby forming closed discharge cells  11 R,  11 G,  11 B. The discharge cells  11 R,  11 G,  11 B include phosphor layers  13 R,  13 G,  13 B respectively formed of phosphor materials of Red (R), Green (G), and Blue (B) primary colors. The phosphor layers  13 R,  13 G,  13 B are excited by ultraviolet light rays emitted by a plasma discharge to emit visible light rays. 
   Address electrodes  15  extend on the rear substrate  3  and third electrodes  17  (hereinafter referred to as “M-electrodes”) extend on the front substrate  1  in a direction intersecting the address electrodes  15 . 
   As described above, the discharge cells  11 R,  11 G,  11 B are formed as closed structures by the barrier ribs  5  which extend in the longitudinal direction (y-axis direction) of the address electrode  15  and are arranged to be parallel to each other, and by X-electrodes  7  and Y-electrodes  9  which extend in the direction (x-axis direction) intersecting the barrier ribs  5  and are arranged to be parallel to each other. As shown in  FIG. 1 , the barrier ribs  5  and X- and Y-electrodes  7  and  9  intersect each other at right angles, so that the discharge cells  11 R,  11 G,  11 B have a rectangular shape. The barrier ribs  5  extend in y-axis direction and are arranged along the x-axis direction in outer parts of the discharge cells  11 R,  11 G,  11 B. The X- and Y-electrodes  7  and  9  extend in the x-axis direction and are alternately arranged along the y-axis direction in outer parts of the discharge cells  11 R,  11 G,  11 B. When the X- and Y-electrodes  7  and  9  extend in the x-axis direction, the discharge cells  11 R,  11 G,  11 B can be formed in various shapes, such as rectangle, hexagon, or octagon, depending on the shapes of the barrier ribs  5 . 
     FIG. 2  is a top plan view of  FIG. 1 . 
   Referring to  FIG. 2 , the barrier ribs  5  have a predetermined height (in the z-axis direction of  FIG. 2 ) on a dielectric layer  19  of the rear substrate  3 . The height of the barrier rib  5  defines a gap between the front substrate  1  and the rear substrate  3 . The X- and Y-electrodes  7  and  9  extend in the x-axis direction and the barrier ribs  5  are arranged to extend in the y-axis direction between the X- and Y-electrodes  7  and  9 . That is, the barrier ribs  5  are divided by the X- and Y-electrodes  7  and  9  in the y-axis direction of the discharge cells  11 R,  11 G,  11 B. 
   The address electrodes  15  extend in the direction intersecting X-, Y-, and M-electrodes  7 ,  9 , and  17  (i.e. in the y-axis direction of  FIG. 2 ) on the rear substrate  3  and are covered by the dielectric layer  19 . The address electrodes  15  are preferably arranged in the center of the discharge cells  11 R,  11 G,  11 B so that an address discharge occurs during a scan period by interacting with the M electrodes  17  in the center of the discharge cells  11 R,  11 G,  11 B. 
   When an addressing voltage is supplied to the address electrodes  15  and a scan pulse is supplied to the M-electrodes  17 , an address discharge occurs within the discharge cells  11 R,  11 G,  11 B between two selected electrodes and discharge cells  11 R,  11 G,  11 B are selected, so that wall charges are formed within the selected discharge cells  11 R,  11 G,  11 B. 
   The X- and Y-electrodes  7  and  9  intersecting the address electrodes  15  are opposed to each other on both sides of the discharge cells  11 R,  11 G,  11 B. During a reset period, a reset discharge occurs due to a rising reset waveform and a falling reset waveform supplied to the M-electrodes  17 . During a scan period subsequent to the reset period, as described above, an address discharge occurs due to a scan pulse waveform supplied to the M-electrodes  17  and a pulse waveform supplied to the address electrode  15 . Subsequently, during a sustain period, a sustain discharge occurs due to a sustain voltage supplied to the X- and Y-electrodes  7  and  9 . As a result, an image is displayed on the PDP. 
   The X- and Y-electrodes  7  and  9  are arranged to act on all of the discharge cells  11 R,  11 G,  11 B adjacent to the address electrodes  15  in the longitudinal direction. The M-electrodes  17  are formed on the front substrate  1  to be between the X- and Y-electrodes  7  and  9 . That is, between the front substrate  1  and the rear substrate  3 , the X-, Y-, and M-electrodes  7 ,  9 , and  17  are arranged in the repeating order of X-M-Y-M-X, . . . , Y-M-X-M-Y. That is, the X- and Y-electrodes  7  and  9  are alternately arranged, and the M-electrodes  17  are provided between the X- and Y-electrodes  7  and  9 , and between the Y- and X-electrodes  9  and  7 , respectively. 
     FIG. 3  is a cross-sectional view taken along the line III-III of  FIG. 1 . 
   Referring to  FIG. 3 , the X- and Y-electrodes  7  and  9  are provided on the dielectric layer  19  to form both sides of the y-axis direction of the discharge cells  11 R,  11 G,  11 B while intersecting the address electrodes  5 , and are then covered by a dielectric layer  21 . The dielectric layer  21  accumulates wall charges when the X- and Y-electrodes  7  and  9  generate an opposing discharge. The phosphor layers  13 R,  13 G,  13 B are formed on the dielectric layer  21 . Accordingly, the phosphor layers  13 R,  13 G,  13 B are formed on the dielectric layer  19  of the rear substrate  3 , inner lateral surfaces of the barrier ribs  5 , and inner lateral surfaces of the dielectric layer  21  covering the X- and Y-electrodes  7  and  9 . The X- and Y-electrodes  7  and  9  are formed to have a predetermined height in the z-axis direction of  FIG. 1  and extend in the x-axis direction. Furthermore, the X- and Y-electrodes  7  and  9  are arranged parallel to each other on both sides of the discharge cells  11 R,  11 G,  11 B in a longitudinal direction (y-axis direction) of the address electrode  15 . Thus, the above structure of X- and Y-electrodes  7  and  9  enables an opposing discharge, thereby facilitating an improved discharge as compared to a surface discharge. 
   The X- and Y-electrodes  7  and  9  are provided to effect a sustain discharge commonly to adjacent discharge cells  11 R,  11 G,  11 B to eliminate a non-discharge area formed between the adjacent discharge cells  11 R,  11 G  11 B. Accordingly, a discharge area is increased, thereby increasing the discharge efficiency. 
   Also, the X- and Y-electrodes  7  and  9  are provided in non-discharge areas forming peripheral parts of the discharge cells  11 R,  11 G,  11 B. Thus, since visible light rays emitted from the discharge cells  11 R,  11 G,  11 B are not blocked, the X- and Y-electrodes  7  and  9  can be made of non-transparent material and are preferably made of a metallic material such as aluminum that has high electrical conductivity. 
   The M-electrode  17  interacts with the address electrode  15  during a scan period (i.e. a scan pulse is supplied to the M-electrode  17  and an addressing voltage is supplied to the address electrode  15 ) to generate an address discharge and to select the discharge cells  11 R,  11 G,  11 B. 
   In the present embodiment, the X- and Y-electrodes  7  and  9  act to supply the voltage required for a sustain discharge, and the M-electrode  17  acts to supply scan and reset pulse waveforms. However, the X-, Y-, and M-electrodes  7 ,  9 , and  17  can act differently according to the voltage waveforms supplied to each of them. 
   While the M-electrode  17  can be formed of either a transparent electrode  17   a  or a bus electrode  17   b , the M-electrode  17  is formed of both the transparent electrode  17   a  and the bus electrode  17   b  in the present embodiment. The transparent electrode  17   a , together with the address electrode  15 , acts to generate an address discharge inside the discharge cells  11 R,  11 G,  11 B, and can be formed of a transparent Indium Tin Oxide (ITO) to ensure a high aperture ratio. The bus electrode  17   b  acts to ensure a high electrical conductivity by compensating for a high electrical resistance of the transparent electrode  17   a , and can be formed of a metallic material such as aluminum. Also, preferably, the bus electrode  17   b  is provided in the center of the discharge cells  11 R,  11 G,  11 B and has a narrower width Wb than a width Wa of the transparent electrode  17   a  so that blockage of visible light rays can be minimized. The M-electrode  17  is covered with a dielectric layer  23  for accumulating wall charges and a MgO protective layer  25  for protecting the dielectric layer  23  and for increasing the emission of secondary electrons. 
     FIG. 4  is a cross-sectional view of a PDP in accordance with a second embodiment of the present invention. 
   Referring to  FIG. 4 , the construction of the second embodiment is the same or similar to that of the first embodiment. Thus, only a detailed description of different parts between the first and second embodiments is provided below. 
   In the first embodiment, the X- and Y-electrodes  7  and  9  form both sides of the discharge cells  11 R,  11 G,  11 B in the longitudinal direction (y-axis direction) of the address electrode  15 . On the other hand, in the second embodiment, the X-electrodes  7  are separately formed on both sides of the first barrier rib  7   a  interposed therebetween, and the Y-electrodes  9  are separately formed on both sides of the second barrier rib  9   b  interposed therebetween. 
   The X-electrode  7  is provided between the front substrate  1  and the rear substrate  3  to have the same height (in the z-axis direction) as the first barrier rib  7   a . The Y-electrode  9  is provided between the front substrate  7  and the rear substrate  9  to have the same height (in the z-axis direction) as the second barrier rib  9   a.    
   The X- and Y-electrodes  7  and  9  are formed by applying an electrically conductive material on the first and second barrier ribs  7   a  and  9   a , respectively, by deposition or the like, and applying a dielectric material on the electrically conductive material. Accordingly, the X-electrodes  7  are formed on both sides of the first barrier rib  9   a  and covered with the dielectric layer  21 , while the Y-electrodes  9  are formed on both sides of the second barrier rib  9   a  and covered with the dielectric layer  21 . As in the first embodiment, to obtain such an effect that the X- and Y-electrodes  7  and  9  are alternately arranged, the same sustain voltage should be supplied to the separated X-electrodes  7  and the same sustain voltage should be supplied to the separated Y-electrodes  9 . 
     FIG. 5  is a cross-sectional view of a PDP in accordance with a third embodiment of the present invention. 
   Referring to  FIG. 5 , the construction of the third embodiment is the same or similar to that of the second embodiment. Thus, only a detailed description of the different parts between the second and third embodiments is provided below. 
   While the X- and Y-electrodes  7  and  9  are formed to have the same height as the first and second barrier ribs  7   a  and  9   a  in the second embodiment, the X- and Y-electrodes  7  and  9  are formed to be lower in height than the first and second barrier ribs  7   a  and  9   a  in the third embodiment. The X- and Y-electrodes  7  and  9  are provided in the center of the discharge cells  11 R,  11 G,  11 B formed between the front substrate  1  and the rear substrate  3  in a height direction (the z-axis direction) of the discharge cells. Accordingly, the X- and Y-electrodes  7  and  9 , and the first and second barrier ribs  7   a  and  9   a , which are not covered by the X- and Y-electrodes  7  and  9 , are covered with the dielectric layer  21 . The third embodiment exemplifies, together with the second embodiment, that the X- and Y-electrodes  7  and  9  can be implemented in various manners. 
   According to the above-mentioned embodiments, it is possible to prevent a short-circuit condition since the X- and Y-electrodes  7  and  9  are separately formed on both sides of the discharge cells  11 R,  11 G,  11 B. 
   As is apparent from the above description, according to the present invention, a discharge cell has barrier ribs formed on its two sides and first and second electrodes (X- and Y-electrodes) formed on the other two sides. Accordingly, an opposing discharge can be generated between the first and second electrodes, thereby facilitating a discharge. Furthermore, since a third electrode (M-electrode) intersecting an address electrode in the discharge cell is formed on a front substrate, it is possible to minimize the blockage of visible light rays in a discharge area and thus to improve the discharge efficiency. 
   While the present invention has been 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 scope of the present invention as defined by the following claims.