Patent Abstract:
Provided is a plasma display panel that can increase bright room contrast and luminous efficiency. The plasma display panel includes a first substrate; a second substrate which is separated from the first substrate and faces the first substrate; a plurality of barrier ribs formed between the first and second substrates and defining a plurality of discharge cells; a plurality of sustain electrodes formed between the first and second substrates, comprising inner sustain electrodes and outer sustain electrodes; a plurality of scan electrodes formed in parallel to the sustain electrodes and comprising inner scan electrodes and outer scan electrodes; a plurality of address electrodes formed between the first and second substrates and extending in a direction crossing an extending direction of the sustain electrodes and the scan electrodes; an inner sustain connection electrode that electrically connects the inner sustain electrodes formed in adjacent discharge cells arranged in an extending direction of the address electrodes; and a discharge prevention element that prevents the generation of discharge in a non-discharge region around the inner sustain connection electrode, wherein the sustain electrodes and the scan electrodes are repeatedly and alternately disposed in each of the discharge cells, and adjacent electrodes of the outer sustain and outer scan electrodes formed in the two adjacent discharge cells arranged in an extending direction of the address electrodes are electrically connected to each other.

Full Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
     This application claims the benefit of Korean Patent Application Nos. 10-2006-0028056 and 10-2006-0028057, both filed on Mar. 28, 2006, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present embodiments relate to a plasma display panel (PDP), and more particularly, to a PDP that can prevent neon discharge in non-discharge regions around a display region of the PDP that does not have transparent electrodes (ITOless). 
     2. Description of the Related Art 
     A PDP is a flat panel display device that displays images using plasma discharge of a gas in discharge cells constituting pixels. Recently, PDPs have received much attention as large flat panel display apparatuses since they can be manufactured to be thin, have a wide viewing angle, and can display high quality images. 
     A conventional alternating current (AC) three-electrode surface discharge type PDP includes a front panel and a rear panel. The front panel includes a front substrate, a plurality of sustain electrode pairs that are formed on the front substrate and generate sustain discharge, an upper dielectric layer that covers the sustain electrode pairs, and a passivation film coated on the upper dielectric layer. The rear panel includes a rear substrate, a plurality of address electrodes which are formed on the rear substrate and generate address discharge together with the sustain electrode pairs, a lower dielectric layer that covers the address electrodes, and a plurality of barrier ribs that define a plurality of discharge cells constituting pixels. A sealing layer is formed using frit glass on edges of the front panel and the rear panel. After aligning the front and rear panels, the sealing layer formed of frit glass is annealed to combine the front and rear panels by melting the sealing layer. Afterwards, air in each of the discharge cells and non-discharge regions is exhausted and a discharge gas is filled in the discharge cells. The discharge gas can be a gas mixture containing Ne gas mixed with Xe gas. 
     When a pulse voltage greater than a discharge breakdown voltage is alternately applied to the sustain electrode pairs of each of the discharge cells, plasma discharge is generated. Xe gas atoms are excited by colliding with electrons, and the Xe gas atoms generate ultraviolet rays when the excited Xe gas atoms are stabilized. The ultraviolet rays excite red, green, and blue color phosphor layers formed on the barrier ribs, and visible light is emitted from the phosphor layers and is transmitted through the front panel forming an image. However, the neon gas atoms emit orange visible light when the excited neon gas atoms are stabilized. The orange visible light reduces color purity and contrast of the image, thereby reducing display quality. In the prior art, to avoid the color purity and contrast reducing problem, a red color filter, a green color filter, and a blue color filter are formed corresponding to the red, green, and blue color discharge cells on a side of a panel through which the visible light passes, or dielectric color filters in which color filters respectively formed one unit in a dielectric layer are used to block the orange visible light emitted from the neon gas atoms. In this way, the affect of the neon discharge in the discharge cells is reduced. 
     Non-discharge regions defined by an outermost barrier rib and the frit glass sealing layer are located around a display region which consists of discharge cells, and the non-discharge regions are also filled with the discharge gas that contains neon gas. End terminals of the sustain electrode pairs that generate sustain discharge pass through the non-discharge regions located on left and right sides of the PDP. During a sustain discharge, a neon discharge can occur between the sustain electrodes and scan electrodes. 
     In particular, in the case of ITOless PDPs that do not use transparent electrodes to reduce material costs, at least two sustain electrodes and scan electrodes respectively are used instead of using one sustain electrode and scan electrode, to achieve stable discharge and to increase light emission efficiency. Also, to prevent crosstalk between adjacent discharge cells and to increase brightness, the sustain electrodes and the scan electrodes can be modified in various ways including the numbers thereof, location arrangement, and methods of driving. In this case, neon discharge is more likely to occur in the non-discharge regions. 
     When neon discharge occurs in the non-discharge regions located around the discharge region, orange visible light generated from the neon discharge is transmitted through the front panel, thereby reducing display quality of images of the PDP. 
     SUMMARY OF THE INVENTION 
     The present embodiments provide a plasma display panel (PDP) that can increase bright room contrast and luminous efficiency. 
     According to an aspect of the present embodiments, there is provided a plasma display panel comprising: a first substrate; a second substrate which is separated from the first substrate and faces the first substrate; a plurality of barrier ribs formed between the first and second substrates and defining a plurality of discharge cells; a plurality of sustain electrodes formed between the first and second substrates, comprising inner sustain electrodes and outer sustain electrodes; a plurality of scan electrodes formed in parallel to the sustain electrodes and comprising inner scan electrodes and outer scan electrodes; a plurality of address electrodes formed between the first and second substrates and extending in a direction crossing an extending direction of the sustain electrodes and the scan electrodes; an inner sustain connection electrode that electrically connects the inner sustain electrodes formed in adjacent discharge cells arranged in an extending direction of the address electrodes; and a discharge prevention element that prevents the generation of discharge in a non-discharge region around the inner sustain connection electrode, wherein the sustain electrodes and the scan electrodes are repeatedly and alternately disposed in each of the discharge cells, and adjacent electrodes of the outer sustain and outer scan electrodes formed in the two adjacent discharge cells arranged in an extending direction of the address electrodes are electrically connected to each other. 
     The discharge prevention element may be a dummy barrier rib formed on the second substrate. 
     Some embodiments relate to a display panel wherein each of a plurality of voltages applied to the inner sustain electrodes and the outer sustain electrodes is independently controlled, and each of a plurality of voltages applied to the inner scan electrodes and the outer scan electrodes is independently controlled. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and advantages of the present embodiments will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
         FIG. 1  is a plan view illustrating a plasma display panel (PDP) according to an embodiment; 
         FIG. 2  is a cross-sectional view taken along a line II-II of  FIG. 1 , according to an embodiment; 
         FIG. 3  is a plan view illustrating a modified version of the PDP of  FIG. 1 , according to an embodiment; 
         FIG. 4  is a diagram for explaining a method of driving a PDP according to an embodiment; 
         FIG. 5  is a first example timing diagram for explaining a driving signal of a PDP according to an embodiment; 
         FIG. 6  is a second example timing diagram for explaining a driving signal of a PDP according to an embodiment; 
         FIG. 7  is a plan view illustrating a plasma display panel according to another embodiment; 
         FIG. 8  is a plan view illustrating a modified version of the PDP of  FIG. 7 , according to an embodiment; 
         FIG. 9  a plan view illustrating a plasma display panel according to another embodiment; and 
         FIG. 10  is a plan view illustrating a modified version of the PDP of  FIG. 9 , according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present embodiments will now be described more fully with reference to the accompanying drawings in which exemplary embodiments are shown.  FIG. 1  is a plan view illustrating a plasma display panel (PDP) according to an embodiment, and  FIG. 2  is a cross-sectional view taken along a line II-II of  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , the PDP according to the embodiment includes a front panel and a rear panel. The front panel includes a front substrate  10  and the rear panel includes a rear substrate  30 . The rear panel includes a reflective layer (not shown) for reflecting visible light, and the front substrate  10  is formed of a transparent material such as glass so that visible light can be transmitted through the front substrate  10 . Accordingly, visible light generated from phosphor layers, which will be described later, is not transmitted through the rear panel but is transmitted through the front panel. However, the present embodiments are not limited thereto, and can also be applied to a transmission type PDP through which visible light is transmitted without reflection. A sustain electrode pair  20  that generates sustain discharge is formed on the front substrate  10 . 
     Sustain electrode pairs  20  that include sustain electrodes and scan electrodes are disposed parallel to each other in a discharge space of each of discharge cells  114   a  and  114   b . The sustain electrodes include a plurality of outer sustain electrodes  115  and a plurality of inner sustain electrodes  111 , and the scan electrodes include a plurality of inner scan electrodes  121  and a plurality of outer scan electrodes  125 . The inner sustain electrodes  111  and the inner scan electrodes  121  are formed in parallel to each other with respect to the center of the discharge space of each of the discharge cells  114   a  and  114   b , and the outer sustain electrode  115  and the outer scan electrodes  125  are respectively formed on outside the inner sustain electrodes  111  and the inner scan electrodes  121 . 
     The sustain electrodes and the scan electrodes are repeatedly and alternately disposed in the discharge cells  114   a  and  114   b . That is, the sustain electrodes and the scan electrodes are arranged in an order such that the outer sustain electrodes  115 , the inner sustain electrodes  111 , the inner scan electrodes  121 , and the outer scan electrodes  125  are formed in parallel to each other parallel to each other in each discharge cell  114   a . In the discharge cell  114   b  adjacent to the discharge cell  114   a  in a vertical direction (in an extending direction of address electrodes  32 ), the outer scan electrodes  125 , the inner scan electrodes  121 , the inner sustain electrodes  111 , and the outer sustain electrodes  115  are sequentially disposed parallel to each other. In another discharge cell below the discharge cell  114   b  (adjacent to the discharge cell  114   b  in the extending direction of the address electrodes  32 ), the sustain electrodes and the scan electrodes are formed in parallel to each other. 
     The inner sustain electrodes  111  of the two adjacent discharge cells  114   a  and  114   b  extending in the direction in which the barrier ribs  33  extend (in the extending direction of the address electrodes  32 ), are electrically connected to each other by an inner sustain connection electrode  112 . An inner sustain terminal electrode  113  is connected to the inner sustain connection electrode  112 , and although not shown, the inner sustain terminal electrode  113  is electrically connected to a signal transmission element (not shown) such as a tape carrier package or a chip on film that transmits electrical signals for driving the inner and outer sustain electrodes  111  and  115 . 
     The outer sustain electrodes  115  of the two adjacent discharge cells  114   a  and  114   b  extending in the direction in which the barrier ribs  33  extend, are electrically connected to each other by an outer sustain connection electrode  116 . The inner sustain terminal electrode  113  is connected to the outer sustain connection electrode  116 , and is electrically connected to a signal transmission element (not shown). The outer scan electrodes  125  of the two adjacent discharge cells  114   a  and  114   b  extending in a direction in which the barrier ribs  33  extend are electrically connected to each other by an outer scan connection electrode  126 . An outer scan terminal electrode  127  is connected to the outer scan connection electrode  126 , and is also electrically connected to a signal transmission element (not shown) that transmits electrical signals for driving the inner and outer scan electrodes  121  and  125 . 
     The outer sustain electrodes  115 , the inner sustain electrodes  111 , the outer scan electrodes  125 , and the inner scan electrode  121  respectively, are closed loop type electrodes, and formed of an opaque metal that contains, for example, Cr—Cu—Cr, Ag or another material having high electrical conductivity. An upper electrode and a lower electrode of each of the outer sustain electrodes  115 , the inner sustain electrodes  111 , the outer scan electrodes  125 , and the inner scan electrodes  121  are connected by short bars  115   a ,  111   a ,  125   a , and  121   a , respectively. That is, the upper and lower electrodes of the outer sustain electrodes  115  are electrically connected by the short bar  115   a , and the upper and lower electrodes of the inner sustain electrodes  111  are electrically connected by the short bar  111   a . Also, the upper and lower electrodes of the outer scan electrodes  125  are electrically connected by the short bar  125   a , and the upper and lower electrodes of the inner scan electrodes  121  are electrically connected by the short bar  121   a . The short bars  115   a ,  111   a ,  125   a , and  121   a  are formed in a direction substantially perpendicular to the extending direction of the outer sustain electrodes  115 , the inner sustain electrodes  111 , the outer scan electrodes  125 , and the inner scan electrodes  121 , and may be formed at locations corresponding to the barrier ribs  33  to prevent visible light from being blocked by the outer sustain electrodes  115 , the inner sustain electrodes  111 , the outer scan electrodes  125 , and the inner scan electrodes  121 . However, the scope of the present embodiments are not limited thereto, that is, short bars can be formed on locations corresponding to discharge spaces and not to the barrier ribs  33 . The short bars  115   a ,  111   a ,  125   a , and  121   a  ensure the flow of current in the loops of the outer sustain electrodes  115 , the inner sustain electrodes  111 , the outer scan electrodes  125 , and the inner scan electrode  121  even though there is a loss of connection in each of the loops of the outer sustain electrodes  115 , the inner sustain electrodes  111 , the outer scan electrodes  125 , and the inner scan electrode  121 . 
     A front dielectric layer  11  is formed on the front substrate  10  to protect the sustain electrodes and scan electrodes by covering the sustain electrodes and scan electrodes. A passivation film  12  is formed on a surface of the front dielectric layer  11  to protect the front dielectric layer  11  and to facilitate discharge by increasing the emission of secondary electrons during discharge. The passivation film  12  can be formed of MgO, for example. 
     The rear substrate  30  includes address electrodes  32  formed in a direction substantially perpendicular to the direction in which the sustain electrodes and scan electrodes extend. A rear dielectric layer  31  is further formed on the rear substrate  30  to protect the address electrodes  32  by covering the address electrodes  32 . The barrier ribs  33 , are stripe-shaped in the shown embodiment, however the present embodiments are not limited thereto. The barrier ribs  33  are formed on the rear substrate  30  to define the plurality of discharge cells  114   a  and  114   b  in which discharge for generating visible light for displaying images occurs. The barrier ribs  33  prevent crosstalk between the discharge cells  114   a . The barrier ribs  33  according to the present embodiments are not limited to the stripe shape, and can have various polygonal horizontal cross-sections such as rectangular, hexagonal, or octagonal cross-sections; or can have circular or oval cross-sections. Red, green, and blue phosphor layers  13  are formed in the discharge cells  114   a  defined by the barrier ribs  33 . 
     The front panel and the rear panel may be combined by a combining member such as a sealing frit (not shown). A discharge gas including Xe gas and at least one of Ne gas, He gas, and Ar gas is filled in the discharge cells  114   a.    
     Non-discharge cells  114   c  are present in non-discharge regions on outer left and right sides of each of the discharge cells  114   a  in which visible light for displaying images is generated. The non-discharge cells  114   c  can be defined by the barrier ribs  33  and the sealing frit, or by the barrier ribs  33  and other barrier ribs (not shown). The discharge gas is also filled in the non-discharge cell  114   c . The inner sustain connection electrode  112 , the outer scan connection electrode  126 , and the inner scan connection electrode  122  are disposed in the non-discharge cell  114   c  located on a left sided non-discharge region. 
     A portion of the inner sustain connection electrode  112  that generates sustain discharge and portions of the inner scan connection electrode  122  and the outer scan connection electrode  126  are disposed to face each other in the non-discharge region of the non-discharge cells  114   c . The inner sustain connection electrode  112  and the inner and outer scan connection electrodes  122  and  126  that face the inner sustain connection electrode  112  can cause unwanted neon discharge during address discharge and sustain discharge. Neon discharge will be described in brief as follows. A plasma discharge occurs by excitation energy emitted from Xe atoms while the Xe atoms are stabilized, and is accelerated through a penning effect. Penning is a reaction that accelerates an ionization reaction of an element through the formation of another element in a metastable state. Here, the metastable state atoms are neon gas atoms, and the neon discharge firstly occurs since the neon atoms emit energy ahead of the Xe atoms. 
     Accordingly, in order to prevent the occurrence of neon discharge, a dummy barrier rib  134  is formed on the rear substrate  30 . The dummy barrier rib  134  is formed on a location between the inner sustain connection electrode  112  and the inner and outer scan connection electrodes  122  and  126 . That is, the occurrence of the neon discharge in the non-discharge region can be prevented by blocking the discharge space between the inner sustain connection electrode  112  and the inner and outer scan connection electrodes  122  and  126 . 
     The dummy barrier rib  134  can be simultaneously formed when the barrier ribs  33  that define the discharge cells  114   a  are formed or can be formed after the discharge cells  114   a  are formed. The barrier ribs  33  can be formed using various methods such as screen printing, sand blast, lift-off, photolithography, or etching. 
       FIG. 3  is a plan view illustrating a modified version of the PDP of  FIG. 1 . In order to prevent the occurrence of neon discharge, as depicted in  FIG. 3 , additionally, a distance g between the inner sustain connection electrode  112  and the outer scan connection electrode  126 , and between the inner sustain connection electrode  112  and the inner scan connection electrode  122  can be formed greater than a distance h between the inner sustain electrode  111  and the inner scan electrode  121 . 
     The separated distance g between the inner sustain connection electrode  112  and the outer scan connection electrode  126 , and between the inner sustain connection electrode  112  and the inner scan connection electrode  122  can be more than twice the distance h between the inner sustain electrode  111  and the inner scan electrode  121 . The distance g may vary according to the composition of the discharge gas or the magnitude of the voltage applied. Therefore, it is understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present embodiments. 
     Although not shown, neon discharge can be prevented by forming the distance g between the inner sustain connection electrode  112  and the outer scan connection electrode  126 , and between the inner sustain connection electrode  112  and the inner scan connection electrode  122  to be greater than the distance h between the inner sustain electrode  111  and the inner scan electrode  121 . In this case, the distance g between the inner sustain connection electrode  112  and the outer scan connection electrode  126 , and between the inner sustain connection electrode  112  and the inner scan connection electrode  122  can be twice or greater than the distance h between the inner sustain electrode  111  and the inner scan electrode  121 . 
     An operation and function of a PDP according to an embodiment will now be described.  FIG. 4  is a diagram for explaining a method of driving a PDP according to an embodiment. An address display separation (ADS) driving method, which is an example of a method of driving a PDP, will be described with reference to  FIG. 4 . 
     In order to display an image on a PDP in response to external image signals, each of sixty unit image frames must be able to display  256  grey scales per second. Each of the image frames must be completely timely separated. That is, a motion image for one second can be displayed by the sixty unit image frames, which are independently displayed. To display an image, one unit image frame time is divided into eight subfield SF times, that is, from a first subfield SF 1  to an eighth subfield SF 8 , and each subfield SF consists of a series of reset discharges R 1 , R 2 , . . . R 8 , address discharges A 1 , A 2 , . . . A 8 , and sustain discharges S 1 , S 2 , . . . S 8 . Sixty unit image frames having the above configuration consecutively display images for one second to display a motion image, thereby displaying an image using the ADS driving method. 
     However, the PDP illustrated in  FIGS. 1 and 2  employs a light emitting structure in which wall charges are accumulated in the discharge cells  114   a , and visible light is emitted due to sustain discharge generated with the aid of the wall charges. In general, to display an image, discharge is generated in the discharge cells  114   a  and  114   b  included in the PDP. Due to the discharge, the state of the wall charges or the amount of charged particles differ between the discharge cells  114   a  and  114   b , and accordingly, the discharge generated in the discharge cells  114   a  and  114   b  cannot be uniformly controlled. 
     To uniformly control the discharge, a discharge is simultaneously generated in the entire discharge cells  114   a  and  114   b  by applying a voltage higher than a predetermined level. In this way, uniform states of wall charges and charged particles in the discharge cells  114   a  and  114   b  can be achieved. This discharge is called reset discharge. 
     After the reset discharge is generated, address discharge is generated. The address discharge generally denotes that, to select discharge cells  114   a  and  114   b  in which an image is displayed by generating visible light from the discharge cells  114   a  and  114   b  that are selected by the inner scan electrodes  121 , the outer scan electrodes  125  and the address electrodes  32  crossing each other, discharge is generated by applying a pulse voltage to the inner scan electrodes  121 , the outer scan electrodes  125  and the address electrodes  32 , and, as a result, wall charges are generated on inner walls of the discharge cells  114   a  due to the accumulation of charged particles generated during the discharge. In this way, as described above, the address discharge is used to select the discharge cells  114   a  and  114   b  by accumulating wall charges on the inner walls of the discharge cells  114   a , and to cause sustain discharge, which will be described later, with the aid of the wall charges. 
     After the address discharge, sustain discharge is generated to display an image. The sustain discharge is generated to emit a predetermined amount of visible light from the discharge cells  114   a  and  114   b  selected by the address discharge by predetermined times alternately forming potential differences between the sustain electrodes and scan electrodes. The sustain discharge is substantially an operation for displaying an image. 
     Since wall charges are accumulated in the discharge cells  114   a  where the address discharge is generated, when a voltage lower than the discharge breakdown voltage is alternately applied to the plurality of electrode pairs  111  and  121  disposed in all of the discharge cells  114   a  and  114   b , a potential formed by adding a potential formed by the wall charges and a potential formed between the sustain electrodes and scan electrodes exceeds the discharge breakdown voltage. Thus, the sustain discharge is generated only in the discharge cells  114   a  in which the address discharge is generated, and visible light is emitted from the discharge cells  114   a  and  114   b  in which the address discharge is generated. 
     Each of the unit image frames consists of eight sequential subfields, and the unit image frame can display a predetermined grey scale by controlling the generation of sustain discharge in each subfield. The sixty unit image frames each having a predetermined grey scale display an image for one second in one of the pixels. The images displaying for one second in each of the pixels constitute an entire image. 
       FIG. 5  is a first example timing diagram for explaining a driving signal of the PDP illustrated in  FIGS. 1 and 2 , according to an embodiment. Referring to  FIG. 5 , a unit image frame for driving the PDP is divided into a plurality of subfields, each of the subfields consisting of a reset period PR, an address period PA, and a sustain period PS. 
     In the reset period PR, a reset discharge is generated by applying a reset pulse composed of a rising pulse and a falling pulse to the inner and outer scan electrodes  121  and  125 , and by applying a voltage Ve to the sustain electrodes  111  and  115  from the point when the falling pulse of the reset pulse is applied to the inner and outer scan electrodes  121  and  125 . The rising pulse applied to the inner and outer scan electrodes  121  and  125  gradually increases from a voltage Vs and reaches a maximum voltage Vw. Due to applying a rising lamp signal having a gentle slope to the inner and outer scan electrodes  121  and  125 , weak discharge is generated and negative charges begin to accumulate near the inner scan electrode  121  (t 5  to t 10 ). The falling pulse applied to the inner and outer scan electrodes  121  and  125  gradually reduces from the voltage Vs, and finally reaches a voltage Vrf. A portion of the negative charges accumulated on the inner scan electrode  121  is released while discharge is generated (t 20 ). 
     As a result of the reset discharge, all of the discharge cells  114   a  are initialized with an identical state by accumulating negative charges on the inner scan electrode  121  and positive charges on the address electrode  32  in each of the discharge cells  114   a . Thus, the discharge cells  114   a  are in a state that can readily generate next address discharge. In the reset period PR t 5  to t  20 , a voltage having an identical waveform is applied to the inner scan electrode  121  and the outer scan electrode  125 . 
     In the address period PA, address discharge is generated by sequentially applying a scan pulse Vg to the inner scan electrodes  121  in each row and a display data signal voltage Vx to the address electrodes  32  in each column in step with the scan pulse Vg. That is, the address discharge is sequentially performed row by row in such a manner that the display data signal voltage Vx is applied to the address electrodes  32  corresponding to the discharge cells  114   a  to be lighted in a row, and the display data signal voltage Vx is applied to the address electrodes  32  corresponding to the discharge cells  114   a  to be lighted in the next row. Due to the address discharge, discharge cells  114   a  in which sustain discharge is generated in the sustain period PS are selected. During the address period PA, a ground voltage Vg is applied to the inner scan electrode  121 , and a positive scan voltage Vsc is applied to the address electrode  32 . Also, in the address period PA, a positive voltage Ve is continuously applied to the inner sustain electrode  111 . Address discharge is generated by a wall voltage caused by negative charges near the scan electrodes  121  and a wall voltage caused by positive charges near the address electrodes  32  together with the display data signal voltage Vx. As a result, positive charges are accumulated on the inner scan electrode  121  and negative charges are accumulated on the sustain electrode  111  (t 30 ). 
     Since a voltage higher than a voltage applied to the inner scan electrode  121  is applied to the outer scan electrode  125 , the address discharge does not progress toward the outer scan electrode  125 . Similarly, since a voltage higher than a voltage applied to the outer sustain electrode  115  is applied to the inner sustain electrode  111 , the address discharge does not progress toward the outer sustain electrode  115 . An address discharge current is greatly reduced since the address discharge is limited in a region between the address electrodes  32  and the inner scan electrode  121  and the inner sustain electrode  111 . Here, waveforms of the voltages applied to the outer scan electrode  125  and the inner scan electrode  121  are different from each other in the period when the address discharge is generated (t 25  to t 30 ), and waveforms of the voltages applied to the inner sustain electrode  111  and the outer sustain electrode  115  are different from each other during the address period (t 20  to t 40 ). 
     During the address discharge, neon discharge can occur between the inner sustain connection electrode  112  formed in the non-discharge region of the non-discharge cells  114   c  located on a left side of the display region and the inner scan electrode  121  and the outer scan connection electrode  126 . This is because the neon discharge has a lower breakdown voltage than that of the Xe discharge. However, a dummy barrier rib  134  according to an embodiment formed between the inner sustain connection electrode  112  and the inner scan electrode  121  and the outer scan connection electrode  126  prevents the generation of neon discharge. Also, neon discharge can be prevented since the distance g between the inner sustain connection electrode  112  and the outer scan connection electrode  126  and between the inner sustain connection electrode  112  and the inner scan connection electrode  122  is greater than the distance h between the inner sustain electrode  111  and the inner scan electrode  121 . 
     Accordingly, image quality of the PDP illustrated in  FIGS. 1 and 2  according to an embodiment can be increased by preventing the generation of orange visible light in the non-display regions around the display region. 
     In the sustain period PS after the address period PA, a sustain pulse is alternately applied to the inner and outer sustain electrodes  111  and  115  and the inner and outer scan electrodes  121  and  125 . Sustain discharge is generated due to collision between the discharge gas and positive charges accumulated near the inner scan electrode  121  migrating to the inner sustain electrode  111  by applying a straight voltage Vs 1  to the inner scan electrode  121 , and negative charges accumulated near the inner sustain electrode  111  migrating to the inner scan electrode  121  by applying a ground voltage Vg. Next, another sustain discharge is generated by diffusing again the negative charges accumulated on the inner scan electrode  121  to the inner sustain electrode  111  by applying the ground voltage Vg to the inner scan electrode  121 , and migrating the positive charges accumulated on the inner sustain electrode  111  to the inner scan electrode  121  by applying the straight voltage Vs to the inner sustain electrode  111 . 
     The sustain discharge is performed in the discharge cells  114   a  selected by the address discharge as described above. The control of brightness in the unit image frame consisting of the plurality of subfields is performed according to the number of times of sustain discharge based on a weighted grey scale allocated to each of the subfields. As a result, a grey scale brightness is displayed in each unit image frame. 
     The sustain pulse alternately has the straight voltage Vs and the ground voltage Vg. Waveforms applied to the inner sustain electrode  111  and the outer sustain electrode  115  during the sustain period PS is identical. Accordingly, the sustain discharge initiated between the inner sustain electrode  111  and the inner scan electrode  121  is diffused towards the outer sustain electrode  115  and the outer scan electrode  125 . As a result, the region of the sustain discharge increases, thereby increasing luminous efficiency. 
     During the sustain discharge, neon discharge can be generated between the inner sustain connection electrode  112  formed in the non-discharge region of the non-discharge discharge cells  114   c  located on a left side of the display region and the inner scan electrode  121  and the outer scan connection electrode  126 . This is because gaps between the inner sustain connection electrode  112  and the inner scan electrode  121  and between the inner sustain connection electrode  112  and the outer scan connection electrode  126  are not large, and because the neon discharge has a lower discharge breakdown voltage than the Xe discharge. However, in the present embodiment, the dummy barrier rib  134  formed between the inner sustain connection electrode  112  and the inner scan electrode  121  and the outer scan connection electrode  126  prevents the generation of neon discharge. Also, neon discharge is prevented since the distance g between the inner sustain connection electrode  112  and the outer scan connection electrode  126 , and between the inner sustain connection electrode  112  and the inner scan connection electrode  122  is greater than the distance h between the inner sustain electrode  111  and the inner scan electrode  121 . Therefore, image quality of the PDP illustrated in  FIGS. 1 and 2  according to an embodiment can be increased by preventing the generation of orange visible light in the non-display discharge cells  114   c  around the display region. 
       FIG. 6  is a second example timing diagram for explaining a driving signal of the PDP illustrated in  FIGS. 1 and 2 , according to an embodiment. Referring to  FIG. 6 , during a reset period PR and a address period PA, the driving signal has the same waveforms as the waveforms of  FIG. 5 . Accordingly, the functions and operations of the PDP in the reset period PR and the address period PA are identical to those described with reference to  FIG. 5 . 
     During a sustain period PS, a sustain voltage Vs 2  applied to the outer sustain electrode  115  is higher than a sustain voltage Vs applied to the inner sustain electrode  111 , and the sustain voltage Vs 2  applied to the outer scan electrode  125  is higher than the sustain voltage Vs applied to the inner scan electrode  121 . Accordingly, a sustain discharge generated between the inner sustain electrode  111  and the inner scan electrode  121  is readily diffused towards the outer sustain electrode  115  and the outer scan electrode  125 . That is, a gap between the inner and outer scan electrodes  121  and  125  can be increased as the larger the voltage differences between the outer sustain electrode  115  and the inner sustain electrode  111  and between the outer scan electrode  125  and the inner scan electrode  121 . As a result, the discharge region increases, thereby increasing luminous efficiency of the PDP. 
       FIG. 7  is a plan view illustrating a PDP according to another embodiment. In explaining the present embodiment, differences between  FIGS. 1 through 3  and  FIG. 7  will be described. 
     Sustain electrodes and scan electrodes are disposed parallel to each other in a discharge space of each of a plurality of discharge cells  214   a . Each of the sustain electrodes includes an outer sustain electrode  215  and an inner sustain electrode  211 , and each of the scan electrodes includes an inner scan electrode  221  and an outer scan electrode  225 . That is, the inner sustain electrode  211  and the inner scan electrode  221  are formed parallel to each other on both sides of the center of a discharge space of each of discharge cells  214   a    214   b , and the outer sustain electrode  215  and the outer scan electrode  225  are respectively located on outsides of the inner sustain electrode  211  and the inner scan electrode  221 . 
     The sustain electrodes and the scan electrodes are repeatedly and alternately disposed in each of the discharge cells  114   c . That is, the sustain electrodes and the scan electrodes are formed in an order in which the sustain electrodes and the scan electrodes are formed in parallel with other in one of the discharge cells  214   a , in another discharge cell  214   b  adjacent to a lower side of the discharge cell  214   a  in a vertical direction (in an extending direction of address electrodes  32 ) to the discharge cells  214   a , a scan electrode and a sustain electrode are formed in parallel to each other, and, in another discharge cell (not shown) located below the discharge cell  214   b , a sustain electrode and a scan electrode are formed parallel to each other. 
     The outer sustain electrode  215  is a closed loop shaped electrode, and an upper electrode and a lower electrode of the outer sustain electrode  215  are respectively disposed in two adjacent discharge cells  214   a  and  214   b  extending in a vertical direction. Accordingly, a sustain electrode  215   b  and the inner sustain electrode  211  in one discharge cell  214   a  are split electrodes. The outer scan electrode  225  is also a closed loop shaped electrode, and an upper electrode and a lower electrode of the outer scan electrode  225  are respectively disposed in two adjacent discharge cells  214   a  and  214   b  extending in a vertical direction. Accordingly, the scan electrodes  221  and  225  in one discharge cell  214   a  are split electrodes. However, the inner scan electrode  221  and the inner sustain electrode  211  are not loop shaped electrodes. 
     The inner sustain electrodes  211  in the two adjacent discharge cells  214   a  and  214   b  arranged in an extending direction of barrier ribs  33  (in an extending direction of address electrodes  32 ) are electrically connected by an inner sustain connection electrode  212 . An outer sustain terminal electrode  217  is connected to an outer sustain connection electrode  216 , and an inner sustain terminal electrode  213  is connected to the inner sustain connection electrode  212 . Thus, the outer sustain terminal electrode  217  and the inner sustain terminal electrode  213  are disposed in a left side of the PDP, and are electrically connected to each of a plurality of signal transmission elements (not shown). Also, an inner scan terminal electrode  223  and an outer scan terminal electrode  227  are disposed in a right side of the PDP, and are electrically connected to each of a plurality of signal transmission elements (not shown). 
     To drive the PDP according to the present embodiment, the voltage waveforms described above with reference to  FIGS. 5 and 6  are applied. Neon discharge can occur in a discharge cell  214   c  corresponding to a non-discharge space outside the PDP between the inner sustain connection electrode  212  and the outer scan electrode  225 . To prevent neon discharge, a dummy barrier rib  234  is formed in a location between the inner sustain connection electrode  212  of a rear substrate  30  and the outer scan electrode  225 . Due to the formation of the dummy barrier rib  234 , the generation of neon discharge between the inner sustain connection electrode  212  and the outer scan electrode  225  can be prevented, and thus, the generation of orange visible light from the non-discharge cell  214   c  around a display region can be prevented. 
       FIG. 8  is a plan view illustrating a modified version of the PDP of  FIG. 7 , according to an embodiment. Also, as depicted in  FIG. 8 , neon discharge can be prevented since a distance g between an inner sustain connection electrode  212  and an outer scan connection electrode  226 , and between the inner sustain connection electrode  212  and an inner scan connection electrode  222  is greater than a distance h between an inner sustain electrode  211  and an inner scan electrode  221 . Accordingly, the degradation of image quality of the PDP according to the current embodiment can be prevented. 
       FIG. 9  a plan view illustrating a PDP according to another embodiment. Here, the differences between the present embodiment and the previous embodiments will be mainly described. 
     Sustain electrodes and scan electrodes are formed in parallel to each other in discharge spaces of each of discharge cells  314   a  and  314   b . Each of the sustain electrodes includes an outer sustain electrode  315  and an inner sustain electrode  311 , and each of the scan electrodes includes an inner scan electrode  321  and an outer scan electrode  325 . The inner sustain electrode  311  and the inner scan electrode  321  are formed in parallel to each other on both sides of the center of a discharge space of each of the discharge cells  314   a  and  314   b , and the outer sustain electrode  315  and the outer scan electrode  325  are respectively formed on outer sides of the inner sustain electrode  311  and the inner scan electrode  321 . 
     The sustain electrodes and the scan electrodes are repeatedly and alternately formed in each of the discharge cells  314   a  and  314   b . That is, the sustain electrodes and the scan electrodes are formed in an order in which the sustain electrodes and the scan electrodes are formed in parallel to each other in one of the discharge cells  314   a , in another discharge cell  314   b  adjacent to the discharge cells  314   a  in a vertical direction (in an extending direction of address electrodes  32 ) to the discharge cells  314   a , a scan electrode and a sustain electrode are formed parallel to each other, and, in another discharge cell (not shown) located below the discharge cell  314   b , a sustain electrode and a scan electrode are formed parallel to each other. 
     The outer sustain electrode  315  is a closed loop shaped electrode, and an upper electrode and a lower electrode of the outer sustain electrode  315  are respectively disposed in two adjacent discharge cells  314   a  and  314   b  extending in a vertical direction. Accordingly, the outer sustain electrode  315  and the inner sustain electrode  311  in one discharge cell  314   a  are split electrodes. The outer scan electrode  325  is also a closed loop shaped electrode, and an upper electrode and a lower electrode of the outer scan electrode  325  are respectively disposed in two adjacent discharge cells  314   a  and  314   b  extending in a vertical direction. Accordingly, the outer scan electrode  325  in one discharge cell  314   a  is a split electrode. However, the inner scan electrode  321  and the inner sustain electrode  311  are not loop shaped electrodes. 
     Transparent electrodes  318 ,  314 ,  328 , and  324  are further formed on each of the outer sustain electrode  315 , the inner sustain electrode  311 , the outer scan electrode  325 , and the inner scan electrode  321 . That is, the outer sustain electrode  315 , the inner sustain electrode  311 , the outer scan electrode  325 , and the inner scan electrode  321  are opaque metal electrodes, and overlap the transparent electrodes  318 ,  314 ,  328 , and  324  which have a width greater than that of the opaque metal electrodes  315 ,  311 ,  325 , and  321 . Due to the formation of the transparent electrodes  318 ,  314 ,  328 , and  324 , the widths of the opaque metal electrodes  315 ,  311 ,  325 , and  321  can be reduced. As a result, the opening rate of the discharge cells  314   a  and  314   b  can be increased and a discharge gap can be reduced, thereby readily generating discharge. 
     The inner sustain electrodes  311  in the two adjacent discharge cells  314   a  and  314   b  arranged in an extending direction of barrier ribs  33  (in an extending direction of the address electrodes  32 ) are electrically connected to each other by an inner sustain connection electrode  312 . An outer sustain terminal electrode  317  is connected to an outer sustain connection electrode  316 , an inner sustain terminal electrode  313  is connected to an inner sustain connection electrode  312 , and the outer sustain terminal electrode  317  and the inner sustain terminal electrode  313  are disposed on a left side of the PDP and are respectively electrically connected to a plurality of signal transmission elements. Also, an inner scan terminal electrode  323  and an outer scan terminal electrode  327  are disposed on a right side of the PDP and are respectively electrically connected to a plurality of signal transmission elements. 
     In order to drive the PDP according to the present embodiment, the waveforms described with reference to  FIGS. 5 and 6  can be applied. Neon discharge can occur in a non-discharge cell  314   c  corresponding to a space between the inner sustain connection electrode  312  and the outer scan electrode  325  in a non-discharge region outside a discharge region. To prevent neon discharge, a dummy barrier rib  334  is formed in a location between the inner sustain connection electrode  312  and the outer scan electrode  325 . Due to the formation of the dummy barrier rib  334 , the generation of neon discharge between the inner sustain connection electrode  312  and the outer scan electrode  325  can be prevented, and thus, the generation of orange visible light from the non-discharge cell  314   c  around a display region can be prevented. 
       FIG. 10  is a plan view illustrating a modified version of the PDP of  FIG. 9 , according to an embodiment. Referring to  FIG. 10 , neon discharge can be prevented since a distance g between the inner sustain connection electrode  312  and the outer scan connection electrode  326  and between the inner sustain connection electrode  312  and the inner scan connection electrode  322  is greater than a distance h between the inner sustain electrode  311  and the inner scan electrode  321 . Therefore, the degradation of image quality of the PDP according to the current embodiment can be prevented. 
     While the present embodiments have been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present embodiments as defined by the following claims.

Technology Classification (CPC): 7