Patent Publication Number: US-2007120770-A1

Title: Plasma display apparatus

Description:
This Nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 10-2005-0115177 filed in Korea on Nov. 30, 2005 the entire contents of which are hereby incorporated by reference.  
     BACKGROUND  
      1. Field  
      The present invention relates to a plasma display apparatus  
      2. Discussion of Related Art  
      In general, a Plasma Display Panel (hereinafter, referred to as “PDP”) is adapted to display an image including characters and/or graphics by exciting phosphors with ultraviolet rays of 147 nm, which is generated at the time of discharge of an inert mixed gas He+Xe or Ne+Xe.  
       FIG. 1  is an enlarged view of one of discharge cells constituting a conventional AC type PDP. A discharge cell  30  illustrated in  FIG. 1  comprises a front plate and a rear plate. The front plate has a sustain electrode pair  12 A and  12 B, an upper dielectric layer  14  and a protection layer  16 , all of which are sequentially formed over a front substrate  10 . The rear plate has a data electrode  20 , a lower dielectric layer  22 , barrier ribs  24  and a phosphor layer  26 , all of which are sequentially formed over a rear substrate  18 .  
      Each of the sustain electrode pair  12 A and  12 B consists of a transparent electrode, and a metal electrode for compensating for high resistance of the transparent electrode. The sustain electrode pair  12 A and  12 B are divided into a scan electrode  12 A and a sustain electrode  12 B. The scan electrode  12 A mainly supplies a scan signal for address discharge and a sustain sign for sustain discharge, and the sustain electrode  12 B mainly supplies a sustain signal.  
      The data electrode  20  is formed to cross the sustain electrode pair  12 A and  12 B. The data electrode  20  supplies a data signal for address discharge. Charges generated by discharge are accumulated on the upper dielectric layer  14  and the lower dielectric layer  22 . The protection layer  16  serves to prevent damage to the upper dielectric layer  14  due to sputtering at the time of discharge, and also to increase emission efficiency of secondary electrons. The dielectric layers  14  and  22 , and the protection layer  16  serve to lower an externally applied discharge voltage.  
      The barrier ribs  24  provide discharge spaces together with the front and rear substrates  10  and  18 . The barrier ribs  24  are formed parallel to the data electrode  20 , and serve to prevent ultraviolet rays, which are generated at the time of gas discharge, from leaking to neighboring cells. The phosphor layer  26  is coated on surfaces of the lower dielectric layer  22  and the barrier ribs  24 , and generate red, green or blue visible ray. The discharge space is filled with an inert gas, such as He, Ne, Ar, Xe or Kr, for gas discharge, a discharge gas in which the inert gases are combined, or excimer gas capable of generated ultraviolet rays through discharge. The discharge cell  30  constructed above is selected as an opposite discharge by the data electrode  20  and the scan electrode  12 A, and maintains discharge by surface discharge by means of the sustain electrode pair  12 A and  12 B.  
      Accordingly, as the phosphor layer  26  is excited with ultraviolet rays generated at the time of sustain discharge, a visible ray is emitted from the discharge cell  30 . In this case, the discharge cell  30  implements gray levels necessary for image display by controlling a sustain discharge period, that is, the number of sustain discharges according to video data. Three discharge cells respectively coated with the red, green and blue phosphors  26  are combined to implement a color of one pixel.  
       FIG. 2  is a view illustrating an overall form of electrode arrangements of a PDP including the discharge cell illustrated in  FIG. 1 . It can be seen from  FIG. 2  that a plurality of the discharge cells  30  are formed at respective intersections of scan electrode lines Y 1  to Ym, sustain electrode lines Z 1  to Zm, and data electrode lines X 1  to Xn. The scan electrode lines Y 1  to Ym supply a scan pulse and a sustain pulse so that the discharge cells  30  can be scanned on a line basis and discharge can be sustained in the discharge cells  30 . The sustain electrode lines Z 1  to Zm commonly supply a sustain pulse so that discharge can be sustained in the discharge cells  30  along with the scan electrode lines Y 1  to Ym. The data electrode lines X 1  to Xn supply a data pulse, which is synchronized with the scan pulse, on a line basis so that the discharge cells  30  whose discharge will be sustained according to a logic value of the data pulse can be selected.  
      A representative driving method of the PDP constructed above includes an Address and Display Separation (ADS) driving method in which driving is carried out with a period being divided into an address period and a display period (that is, a sustain period). In the ADS driving method, one frame is divided into a number of subfields corresponding to respective bits of a video data, and the subfields are divided into a reset period, an address period and a sustain period again. In each of the subfields, the same weight is applied to the reset period RPD and the address period APD, but different weights are applied to the sustain period SPD. Accordingly, the PDP represents gray levels corresponding to a video data through a combination of the sustain periods in which discharge is sustained according to a video data.  
       FIG. 3  is a view illustrating a general driving waveform supplied to the PDP illustrated in  FIG. 2  in one subfield of a number of subfields.  
      As illustrated in  FIG. 3 , in the PDP, after the entire lighting discharge is generated using a reset pulse in the reset period RPD, wall charges are erased to reset all the discharge cells  30  to an off state where wall charges remain. To this end, to the scan electrode lines Y 1  to Ym are supplied a ramp-up pulse gradually rising from a step voltage Vs to a peak voltage Vr, and a ramp-down pulse gradually falling from the step voltage Vs to a ground voltage 0V, as a reset pulse RP. A first dark discharge is generated in the entire discharge cells  30  by means of the ramp-up pulse. A second dark discharge is then generated in the entire discharge cells  30  by means of the ramp-down pulse and a bias pulse BP supplied to the sustain electrode lines Z 1  to Zm. Thereafter, as the wall charges formed in the scan electrode lines Y 1  to Ym and the sustain electrode lines Z 1  to Zm are decreased according to the ramp-down pulse, the entire discharge cells  30  are reset to an off state where the wall charges remain. In the reset period RPD, the voltage of the data electrode lines X 1  to Xn is fixed to the ground voltage 0V.  
      In an address period APD, a scan pulse SP is supplied to the scan electrode lines Y 1  to Ym on a line basis, and a data pulse DP is selectively supplied to each of the data electrode lines X 1  to Xn in synchronization with the scan pulse SP. Thus, an address discharge is generated from discharge cells to which the data pulse DP and the scan pulse SP have been supplied, so that the discharge cells become an on state where wall charges for a next sustain discharge are sufficiently formed. However, an address discharge is not generated from discharge cells to which the data pulse DP and the scan pulse SP have not been supplied, so that the discharge cells are kept to an off state.  
      In a sustain period SPD, Y and Z sustain pulses SUSPy and SUSPz are alternatively supplied to the scan electrode lines Y 1  to Ym and the sustain electrode lines Z 1  to Zm, so that the state of the discharge cell decided in the address period APD is sustained. In more detail, discharge cells of an on state where wall charges have been sufficiently formed in the address period APD are kept to the on state by means of discharge by the Y and Z sustain pulses SUSPy and SUSPz, and discharge cells of an off state are kept to the off state without discharge. In an erase period EPD posterior to the sustain period SPD, an erase pulse EP is supplied to the sustain electrode lines Z 1  to Zm to generate an erase discharge, thereby erasing wall charges existing in the entire discharge cells  30 .  
       FIG. 4  is a view illustrating a conventional plasma display apparatus.  
      As illustrated in  FIG. 4 , a conventional plasma display apparatus comprises a scan driver  45  for driving the scan electrode lines Y 1  to Ym of a PDP  40 , a sustain driver  47  for driving the sustain electrode lines Z 1  to Zm, a data driver  49  for driving the data electrode lines X 1  to Xm, a control board  42  for controlling the scan driver  45 , the sustain driver  47  and the data driver  49 , and a power supply board (not shown) for supplying power to each of the scan driver  45 , the sustain driver  47 , the data driver  49  and the control board  42 .  
      The scan driver  45  comprises a scan driver board  44  for generating the reset pulse RP and the scan pulse SP illustrated in  FIG. 3 , and a Y sustain board  46  for generating the Y sustain pulse SUSPy. The scan driver board  44  supplies the scan pulse SP to the scan electrode lines Y 1  to Ym of the PDP  40  via a Y Flexible Printed Circuit (FPC)  51 . The Y sustain board  46  supplies the Y sustain pulse SUSPy to the scan electrode lines Y 1  to Ym via the scan driver board  44  and the Y FPC  51 .  
      The sustain driver  47  comprises a Z sustain board  48  for generating the bias pulse BP and the Z sustain pulse SUSPz illustrated in  FIG. 3 . The Z sustain board supplies the bias pulse BP and the Z sustain pulse SUSPz to the sustain electrode lines Z 1  to Zm of the PDP  40  via a Z FPC  52 .  
      The data driver  49  comprises a data driver board  50  for generating the data pulse DP illustrated in  FIG. 3 . The data driver board  50  supplies the data pulse DP to the data electrode lines X 1  to Xn of the PDP  40  via an X FPC  54 .  
      The control board  42  generates X, Y and Z timing control signals of the scan, sustain and data drivers  45 ,  47  and  49 . The control board  42  supplies the Y timing control signal to the scan driver  45  via the first FPC  56 , the Z timing control signal to the sustain driver  47  via the second FPC  58 , and the X timing control signal to the data driver  49  via the third FPC  60 , respectively.  
      Meanwhile, recently, as the demand for high-resolution products increases, large-sized PDP products implementing Full HD (1920*1080) resolutions have been developed. The large size trend of the PDP has a problem in that though a large size of a Printed Circuit Board (PCB) forming the driving boards shown in  FIG. 4  is required, it is difficult to drive the PDP using a single large-sized PCB in view of the manufacture cost and driving stability. Accordingly, it is inevitably divide the driving boards in order to drive the large size PDP. However, such dividing of the driving boards causes several problems due to deviation in the operating characteristics of several driving elements mounted in the driving boards.  
       FIG. 5  is a view illustrating driving deviation of a sustain pulse depending on the division of a Z sustain board.  
      As illustrated in  FIG. 5 , dividing of the Z sustain board causes deviation AT in terms of time between the sustain pulses output to the sustain electrodes due to deviation in the operating characteristics of several switching elements, etc., which are mounted in each Z sustain board.  
      This driving deviation of the sustain pulses causes the generation of heat due to deviation in the current flowing into a commonly connected part of the sustain electrodes. Consequently, a problem arises because the sustain electrodes are damaged.  
     SUMMARY  
      Accordingly, the present invention provides a plasma display apparatus, which can save the manufacture cost accompanied by a large size of a PDP and can prevent damage to electrodes, by improving driving boards of the plasma display apparatus.  
      A plasma display apparatus according to an embodiment of the present invention may comprise a PDP comprising sustain electrodes commonly connected through a conductive connection pad, two or more Z sustain boards for driving the sustain electrodes, and a current communication unit for electrically connecting the Z sustain boards and communicating current between the Z sustain boards.  
      The current communication unit may comprise a deviation current communication unit for communicating current depending on driving deviation between the Z sustain boards.  
      The current communication unit may have a resistance value smaller than that of the connection pad.  
      The current communication unit may comprise any one of a PCD, a FPC and conductive metal.  
      The current communication unit may electrically connect output terminals of the Z sustain boards.  
      The PDP may have a size greater than 70 inches or more.  
      A plasma display apparatus according to an embodiment of the present invention may comprise a PDP comprising sustain electrodes divided into two or more electrode groups and connected through a conductive connection pad on a electrode-group basis, Z sustain boards for driving the respective electrode groups, and a current communication unit for electrically connecting the Z sustain boards and communicating current between the Z sustain boards.  
      The current communication unit may comprise a deviation current communication unit for communicating current depending on driving deviation between the Z sustain boards.  
      The current communication unit may have a resistance value smaller than that of the connection pad.  
      The current communication unit may comprise any one of a PCD, a FPC and conductive metal.  
      The current communication unit may electrically connect output terminals of the Z sustain boards.  
      The PDP may have a size greater than 70 inches or more. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention will be described in detail with reference to the following drawings in which like numerals refer to like elements.  
       FIG. 1  is an enlarged view of one of discharge cells constituting a conventional AC type PDP;  
       FIG. 2  is a view illustrating an overall form of electrode arrangements of a PDP including the discharge cell illustrated in  FIG. 1 ;  
       FIG. 3  is a view illustrating a general driving waveform supplied to the PDP illustrated in  FIG. 2  in one subfield of a number of subfields;  
       FIG. 4  is a view illustrating a conventional plasma display apparatus;  
       FIG. 5  is a view illustrating driving deviation of a sustain pulse depending on the division of a Z sustain board;  
       FIG. 6  is a view illustrating a plasma display apparatus according to an embodiment of the present invention;  
       FIG. 7  is a view schematically illustrating the plasma display apparatus of  FIG. 6 , which is coupled to one structure of the sustain electrode; and  
       FIG. 8  is a view schematically illustrating the plasma display apparatus of  FIG. 6 , which is coupled to another structure of the sustain electrode. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
      Preferred embodiments of the present invention will be described in a more detailed manner with reference to the drawings.  
       FIG. 6  is a view illustrating a plasma display apparatus according to an embodiment of the present invention.  FIG. 7  is a view schematically illustrating the plasma display apparatus of  FIG. 6 , which is coupled to one structure of the sustain electrode.  
      As illustrated in  FIGS. 6 and 7 , the plasma display apparatus according to an embodiment of the present invention comprises a PDP  400  having scan electrodes Y 1  to Yn, data electrodes X 1  to Xm, and sustain electrodes Z 1  to Zn commonly connected by a conductive connection pad  700 , a scan driver  450  for driving the scan electrodes Y 1  to Yn, a sustain driver  470  comprising two or more Z sustain boards  480   a  and  480   b  for driving the sustain electrodes Z 1  to Zn, a data driver  490  for driving the data electrodes X 1  to Xm, a control board  420  for controlling the scan driver  450 , the sustain driver  470  and the data driver  490 , a power supply board (not shown) for supply power to each of the scan driver  450 , the sustain driver  470  and the data driver  490 , and a current communication unit  690  for electrically connecting the Z sustain boards  480   a  and  480   b  in order to communicate the current depending on driving deviation between the Z sustain boards  480   a  and  480   b.    
      The PDP  400  comprises the sustain electrodes Z 1  to Zn commonly connected to the scan electrodes Y 1  to Yn through the conductive connection pad  700 , and the data electrodes X 1  to Xm crossing the scan electrodes Y 1  to Yn and the sustain electrodes Z 1  to Zn. The size of the PDP  400  may be 70 inches or more.  
      The scan driver  450  comprises a plurality of scan driver boards  440   a  and  440   b , and a plurality of Y sustain boards  460   a  and  460   b . When the PDP  400  is driven, the scan driver boards  440   a  and  440   b  generate a reset pulse and a scan pulse in a reset period and an address period, and the Y sustain boards  460   a  and  460   b  generate a Y sustain pulse in a sustain period. The number of the scan driver boards  440   a  and  440   b  and the Y sustain boards  460   a  and  460   b  is proportional to the screen size of a PDP. The scan driver  450  comprising the plurality of scan driver boards  440   a  and  440   b  and the Y sustain boards  460   a  and  460   b  as described above supplies the scan pulse, generated from the scan driver boards  440   a  and  440   b , to the scan electrodes Y 1  to Yn of the PDP  400  via Y FPCs  510   a  and  510   b , and supplies the Y sustain pulse, generated from the Y sustain boards  460   a  and  460   b , to the scan electrodes Y 1  to Ym via the scan driver boards  440   a  and  440   b  and the Y FPCs  510   a  and  510   b.    
      The sustain driver  470  comprises two or more Z sustain boards  480   a  and  480   b , and the current communication unit  690 . The two or more Z sustain boards  480   a  and  480   b  supply a bias pulse to the sustain electrodes Z 1  to Zn commonly connected through the conductive connection pad  700  during the address period and supply a Z sustain pulse to the sustain electrodes Z 1  to Zn during the sustain period, when the PDP  400  is driven. The current communication unit  690  electrically connects the Z sustain boards  480   a  and  480   b , and communicates the current depending on driving deviation between the Z sustain boards  480   a  and  480   b.    
      The number of the Z sustain boards  480   a  and  480   b  is proportional to the screen size of the PDP  400 . By doing so, the problem of an increased manufacturing cost due to a large size of the driving board required in accordance with a large size of the PDP  400  can be solved.  
      The current communication unit  690  communicates current, which is generated as the sustain electrodes Z 1  to Zn commonly connected via the conductive connection pad  700  is driven, that is, current depending on driving deviation between the Z sustain boards  480   a  and  480   b , between the Z sustain boards  480   a  and  480   b  through the current communication unit  690  using the two or more Z sustain boards  480   a  and  480   b . Accordingly, damage to the sustain electrodes Z 1  to Zn near the conductive connection pad  700  can be prevented.  
      As illustrated in  FIG. 8 , a method may be proposed in which the sustain electrodes Z 1  to Zn are divided into two or more electrode groups Y 1  to Yn/ 2  and Yn/2+1 to Yn, and the electrode groups are connected through conductive connection pads  800   a  and  800   b  on an electrode-group basis in order to electrically separate the electrode groups on an electrode-group basis. The size of the PDP  400  may be 70 inches or more.  
      It is preferred that the current communication unit  690  have a resistance value smaller than that of the connection pad  700 . A great amount of current is communicated through the current communication unit  690  depending on driving deviation between the Z sustain boards  480   a  and  480   b  by employing a characteristic of current in reverse proportion to a resistance value as described above. Therefore, damage to the sustain electrodes Z 1  to Zn near the conductive connection pad  700  can be prevented.  
      It is preferred that the current communication unit  690  be formed from any one of a PCB, a FPC and conductive metal material in consideration of the manufacturing cost and/or the easiness of manufacture.  
      It is preferable that the current communication unit  690  be constructed to electrically connect output terminals of the Z sustain boards  480   a  and  480   b . In this case, current depending on driving deviation between the Z sustain boards  480   a  and  480   b  can be communicated through the current communication unit  690  more efficiently.  
      The data driver  490  comprises a data driver board  500  for generating the data pulse in the address period when the PDP  400  is driven. The data pulse is supplied to the data electrodes X 1  to Xm of the PDP  400  via a X FPC  540 .  
      The control board  420  generates X, Y and Z timing control signals of the scan driver  450 , the sustain driver  470  and the data driver  490 . The control board  420  supplies the Y timing control signal to the scan driver  450  via first FPCs  560   a  and  560   b , the Z timing control signal to the sustain driver  470  via second FPCs  580   a  and  580   b , and the X timing control signal to the data driver  490  via a third FPC  600 .  
      As described above, the plasma display apparatus according to an embodiment of the present invention is advantageous in that it can save the manufacturing cost accompanied by a large size of a PDP, prevent damage to the sustain electrodes, and provide stable driving.  
      The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.