Patent Publication Number: US-2005140604-A1

Title: Pixel circuit of display device and method for driving the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application claims priority to and the benefit of Korean Patent Application No. 2003-87794, filed on Nov. 29, 2003, the disclosure of which is hereby incorporated herein by reference in its entirety.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a driving circuit of an emitting device used in an image display unit, and a method for driving the same. More particularly, the present invention relates to a pixel circuit of a display device for improving an opening ratio and a contrast ratio of the emitting device.  
      2. Description of Related Art  
      A display device, for example, an organic electroluminescent display device is a display device which generates a display by flowing current from a pixel electrode at each pixel to the organic electroluminescent device. The organic electroluminescent display device is generally divided into a passive matrix type organic electroluminescent display device and an active matrix type organic electroluminescent display device. The active matrix type organic electroluminescent display device generates an image display via switching devices in the pixels inside an organic pixel part, and applying voltage or current according to image data of the pixels.  
       FIG. 1  is a schematic diagram of a conventional active matrix type organic electroluminescent display device according to the prior art.  
      As illustrated in  FIG. 1 , the active matrix type organic electroluminescent display device includes data driver  10  for outputting image data, scan driver  20  for outputting scan signals, and pixel part  30  in which data lines D 1 , D 2 , . . . . Dm- 1 , Dm and gate lines S 1 , S 2 , . . . . Sm- 1 , Sm respectively connected from the data driver  10  and scan driver  20  are longitudinally and laterally arranged. Each of the pixels  40  according to this embodiment are a combination of red, green, and blue unit pixels  41  respectively formed at a crossing portion of gate lines and data lines in the pixel part  30 .  
      The pixels  40  display respective colors according to a combination of red, green, and blue unit colors as unit pixel circuits  41  transmit corresponding driving signals to respective emitting devices according to applied signals when image data is applied to the unit pixel circuits from the data driver  10 , and scan signals are applied to the unit pixel circuits from the scan driver  20 . That is, conventional pixels  40  include driving circuits respectively formed at the unit pixels and connected to the gate lines S 1 , S 2 , . . . , Sm- 1 , Sm and data lines D 1 , D 2 , D 3 , . . . , Dm so that each pixel data is displayed by individually driving the respective unit pixels P(R,G,B) 11 -P(R,G,B)mn according to input scan signals and data signals.  
      The unit pixels P(R,G,B) 11 -P(R,G,B)mn for displaying certain colors include compensation circuits for solving a deviation of signals according to circuit component characteristics. The compensation circuits of the unit pixels include self compensation circuits for compensating a threshold voltage of a driving switching device by connecting the driving switching device to a diode, and non-self compensation circuits equipped with a separate compensation switching device to compensate a threshold voltage of the driving switching device.  
       FIG. 2  is a schematic diagram of a non-self compensation pixel circuit in a conventional display device according to the prior art.  
      Conventional pixels include unit pixels  41   a ,  41   b ,  41   c  where the unit pixels  41   a ,  41   b ,  41   c  respectively include non-self compensation circuits  42 ,  43 ,  44  respectively connected to data lines  11 ,  12 ,  13  and gate line  21  to compensate for a threshold voltage of a driving transistor. The unit pixels  41   a ,  41   b ,  41   c  also respectively include capacitors C 1 , C 2 , C 3  connected to the non-self compensation circuits  42 ,  43 ,  44  to store data, and thin film transistors M 1 , M 2 , M 3  having gates respectively connected to non-self compensation circuits  42 ,  43 ,  44 , having sources connected to their respective power supply voltages, and having drains respectively connected to emitting devices R, G, B. A red electroluminescence (EL) device R is included in unit pixel  41   a , green EL device G is included in unit pixel  41   b , and blue EL device B is included in unit pixel  41   c.    
      Switching transistors (not shown) included in the non-self compensation circuits  42 ,  43 ,  44  are switched on by scan signals for transmitting data signals if the data signals are applied through the data lines  11 ,  12 ,  13  and scan signals are sequentially applied to the unit pixels  41   a ,  41   b ,  41   c  through the gate line  21 . The transmitted data signals are respectively stored in the capacitors C 1 , C 2 , C 3  so that the data signals stored in the capacitors C 1 , C 2 , C 3  may be applied to the thin film transistors M 1 , M 2 , M 3 . The thin film transistors M 1 , M 2 , M 3  transmit driving signals corresponding to the data signals stored in the capacitors C 1 , C 2 , C 3  to the respective emitting devices R, G, B connected to the thin film transistors M 1 , M 2 , M 3 . The non-self compensation circuits  42 ,  43 ,  44  output compensation voltages corresponding to threshold voltages of the thin film transistors M 1 , M 2 , M 3  so that the thin film transistors M 1 , M 2 , M 3  output driving signals of the emitting devices R, G, B that correspond to the original data.  
      The unit pixels  41   a ,  41   b ,  41   c  concurrently cause red, green and blue EL devices R, G, B to emit according to the scan signals and data signals so that the pixels  40  may display certain colors.  
       FIG. 3  is a schematic diagram of self compensation circuits in a conventional display device according to the prior art.  
      Pixels  40 ′ in  FIG. 3  include unit pixels  41   d ,  41   e ,  41   f  which are arranged at a crossing portion where data lines  14 ,  15 ,  16  and gate line  22  longitudinally and laterally cross each other so that the unit pixels  41   d ,  41   e ,  41   f  are respectively connected to the data lines  14 ,  15 ,  16  and the gate line  22 . Unit pixel  41   d  includes self compensation circuit  48  connected to data line  14  and gate line  22 . Unit pixel  41   d  further includes capacitor C 1  and thin film transistor M 1  connected to self compensation circuit  48  and to red EL device R via a drain of thin film transistor M 1 . Thin film transistor M 4  is arranged between the drain of thin film transistor M 1  and red EL device R so that thin film transistor M 4  is connected to emission control line  51 .  
      Unit pixel  41   e  includes self compensation circuit  49  connected to data line  15  and gate line  22 . Unit pixel  41   e  further includes capacitor C 2  and thin film transistor M 2  connected to self compensation circuit  49  and to green EL device G via a drain of thin film transistor M 2 . Thin film transistor M 5  is arranged between the drain of thin film transistor M 2  and green EL device G so that thin film transistor M 5  is connected to the emission control line  51 .  
      Unit pixel  41   f  includes self compensation circuit  50  connected to data line  16  and gate line  22 . Unit pixel  41   f  further includes capacitor C 3  and thin film transistor M 3  connected to self compensation circuit  50  and to blue EL device B via a drain of thin film transistor M 3 . Thin film transistor M 6  is arranged between the drain of thin film transistor M 3  and blue EL device B so that thin film transistor M 6  is connected to the emission control line  51 .  
      Thin film transistors M 1 , M 2 , M 3  are switched on to transmit the data signals transmitted through data lines  14 ,  15 ,  16  to capacitors C 1 , C 2 , C 3  if data signals are applied to data lines  14 ,  15 ,  16 , and scan signals are sequentially applied to unit pixels  41   d ,  41   e ,  41   f  through the gate line  22 .  
      Thin film transistors M 4 , M 5 , M 6  prevent driving signals output from thin film transistors M 1 , M 2 , M 3  from applying to EL devices R, G, B during a data charging period responsive to off signals transmitted through the emission control line  51  connected to thin film transistors M 4 , M 5 , M 6  during the data charging period when data signals are stored in capacitors C 1 , C 2 , C 3 .  
      When the data charging period has expired, the data signals are transmitted from capacitors C 1 , C 2 , C 3  to thin film transistors M 1 , M 2 , M 3 . Thin film transistors M 4 , M 5 , M 6  apply driving signals output from thin film transistors M 1 , M 2 , M 3  to EL devices R, G, B according to on signals transmitted through the emission control line  51  connected to thin film transistors M 4 , M 5 , M 6 . Thin film transistors M 1 , M 2 , M 3  output driving currents corresponding to data signals applied to the red, green and blue EL devices R, G, B. Accordingly, the red, green and blue EL devices R, G, B are concurrently emitted so that a pixel  40  displays a certain color.  
       FIG. 4  is a timing graph of a pixel driving method in a conventional display device according to the prior art.  
      First, when scan signal S 1  is applied to gate line S 1 , gate line S 1  is driven, and pixels PR 11 -PB 1   n  connected to gate line S 1  are driven.  
      That is, switching thin film transistors included in the compensation circuits of respective red, green and blue unit pixels PR 11 -PR 1   n , PG 11 -PG 1   n , PB 11 -PB 1   n  connected to gate line S 1  are driven by the scan signal S 1  applied to gate line S 1 . According to the driving of the switching thin film transistors, red, green and blue data signals D 1 (DR 1 -DRn), D 1 (DG 1 -DGn), D 1 (DB 1 -DBn) are concurrently applied to the gates of the driving thin film transistors M 1 , M 2 , M 3  of red, green and blue unit pixels from red, green and blue data lines DR 1 -DRn, DG 1 -DGn, DB 1 -DBn including m data lines D 1 , . . . , Dm.  
      The driving thin film transistors M 1 , M 2 , M 3  of the red, green and blue unit pixels supply driving currents corresponding to the red, green and blue data signals D 1  (DR 1 -DRn), D 1  (DG 1 -DGn), D 1  (DB 1 -DBn) respectively applied to the red, green and blue data lines DR 1 -DRn, DG 1 -DGn, DB 1 -DBn to the red, green and blue EL devices R, G, B. Therefore, EL devices including pixels PR 11 -PB 1   n  connected to gate line S 1  are concurrently driven if scan signal is applied to gate line S 1 .  
      In the same way, if scan signal S 2  for driving gate line S 2  is applied to gate line S 2 , data signals D 2 (DR 1 -DRn), D 2 (DG 1 -DGn), D 2 (DB 1 -DBn) are applied to pixels PR 21 -PR 2   n , PG 21 -PG 2   n , PB 21 -PB 2   n  connected to gate line S 2  from the red, green and blue data lines DR 1 -DRn, DG 1 -DGn, DB 1 -DBn.  
      EL devices including pixels PR 21 -PR 2   n , PG 21 -PG 2   n , PB 21 -PB 2   n  connected to gate line S 2  are concurrently driven by driving current corresponding to data signals D 2 (DR 1 -DRn), D 2 (DG 1 -DGn), D 2 (DB 1 -DBn).  
      Lastly, if scan signal Sm is applied to gate line Sm by repeating the above described actions, EL devices including pixels PRm 1 -PBmn connected to gate line Sm are concurrently driven according to red, green and blue data signals Dm(DR 1 -DRn), Dm(DG 1 -DGn), Dm(DB 1 -DBn) applied to red, green and blue data lines DR 1 -DRn, DG 1 -DGn, DB 1 -DBn.  
      Therefore, if scan signals are sequentially applied to gate line Sm from gate line S 1 , pixels (PR 11 -PB 1   n )-(PRm 1 -PBmn) connected to the respective gate lines S 1 -Sm are sequentially driven to display an image by driving the pixels during a particular frame.  
      One drawback with the above-described method for driving a display drive is that three data lines and three power supply lines are arranged at each pixel, and multiple thin film transistors and compensation circuits and capacitors are required in the pixel circuit of the display device. With respect to the self compensation circuits ( FIG. 3 ), a problem is that the structure of their circuits is complicated, and yield is deteriorated since a separate emission control line for providing emission control signals is generally required. The prior art circuits also have to be generally constructed in a limited space allotted to the pixel part.  
      Furthermore, the prior art has problems that the area of the pixels is decreased as a display device gets more elaborate, making it difficult to arrange many elements in one pixel. An opening ratio is therefore decreased accordingly.  
     SUMMARY OF THE INVENTION  
      According to one embodiment of the present invention, a pixel circuit of an organic electroluminescent display device and method for driving the same is provided that is appropriate for high density and precision, and capable of improving opening ratio and yield.  
      According to another embodiment of the present invention, a pixel circuit of an organic electroluminescent display device and method for driving the same is provided in which pixel circuits are simply constructed and capable of being used in both self compensation circuits and non-self compensation circuits.  
      According to another embodiment of the present invention, a pixel circuit of an organic electroluminescent display device and method for driving the same is provided that is capable of expressing black gradation and improving contrast ratio by driving red, green and blue emitting devices per data charging period and emitting period.  
      According to one embodiment, the present invention is directed to a pixel circuit of a display device including at least two emitting devices and a sequential controller sequentially controlling emission of the at least two emitting devices for a certain period of time in a certain section. A driving device is coupled to the at least two emitting devices for transmitting driving signals to the at least two emitting devices. A compensation circuit outputs voltage for compensating a threshold voltage associated with the driving device. The sequential controller controls the at least two emitting devices so that the at least two emitting devices are emitted only for a particular time period during the certain period of time.  
      The sequential controller sequentially controls the at least two emitting devices by dividing the certain period of time into a data charging period and an emitting period in such a way that the emitting devices are driven only during the emitting period so as to generate a certain color.  
      According to one embodiment, the certain section is a single frame, the certain period of time is a time period of a sub-frame of the single frame, the single frame is divided into at least two sub-frames, and one or more emitting devices are sequentially driven during their respective sub-frames.  
      According to another embodiment, the certain section is a single frame, the certain period of time is a time period of a sub-frame of the single frame, the single frame is divided into at least three sub-frames, two or more emitting devices are sequentially driven during their respecitve sub-frames of the single frame, and one of the two or more of the emitting devices is driven again in at least one remaining sub-frame, or at least two of the two or more emitting devices are concurrently driven in at least one remaining sub-frame.  
      According to one embodiment, the at least one remaining sub-frame is arbitrarily selected from a plurality of sub-frames.  
      The emitting devices may be field emission display (FED) devices, organic electroluminescence (EL) devices, or liquid crystal display (LCD) devices.  
      According to one embodiment, the sequential controller includes a first electrode coupled to the driving device, and a second electrode connected to one of the at least two emitting devices.  
      According to one embodiment, the sequential controller also includes at least one switching device.  
      According to another embodiment, the present invention is directed to a pixel circuit of a display device including red, green and blue EL devices. A driving device coupled to the red, green and blue EL devices transmit driving signals to the red, green and blue EL devices. A sequential controller coupled to the red, green and blue EL devices sequentially controls emission of the red, green and blue EL devices for a certain period of time in a certain section. A sequential control part transmits switching signals to the sequential controller for the certain period of time in the certain section. The sequential controller controls emission of any one of the red, green and blue EL devices for the certain period of time in the certain section associated with a data charging period and an emission period.  
      The sequential controller sequentially controls at least two of the red, green and blue EL devices in such a way that the EL devices are driven only during the emission period by dividing the certain period of time in the certain section into the data charging period and the emission period.  
      According to one embodiment, the certain section is a single frame, the certain period of time is a time period of a sub-frame of the single frame, the single frame is divided into at least two sub-frames, and one or more of the red, green and blue EL devices are sequentially driven during their respective sub-frames.  
      According to another embodiment, the certain section is a single frame, the certain period of time is associated with a sub-frame, the single frame is divided into at least three sub-frames, two or more of the red, green and blue EL devices are sequentially driven during their respective sub-frames of the single frame, and one of the two or more of the EL devices are driven again in at least one remaining sub-frame, or at least two of the two or more EL devices are concurrently driven in the at least one remaining sub-frame.  
      The at least one remaining sub-frame may be arbitrarily selected from a plurality of sub-frames.  
      According to another embodiment, the present invention is directed to a method for driving a pixel circuit of a display device associated with a plurality of gate lines and a plurality of data lines. The method includes sequentially applying scan signals via the gate lines and sequentially applying one or more of the data signals through the data lines, the scan and data signals being concurrently applied during a certain period of time in a certain section. An off signal is applied to a sequential controller for blocking flow of the data signals to electroluminescance (EL) devices during storing of the data signals. An on signal is applied to the sequential conroller associated with the data signals for causing emission of the EL devices responsive to the data signals being stored.  
      According to one embodiment, the certain section is a single frame, the certain period of time is a time period of a sub-frame of the single frame, the single frame is divided into at least two of sub-frames, and one or more of the EL devices are sequentially driven during their respective sub-frames.  
      According to another embodiment, the certain section is a single frame, the certain period of time is a time period of a sub-frame of the single frame, the single frame is divided into at least three sub-frames, at least two of the red, green and blue EL devices are sequentially driven during their respective subframes of the single frame, and one of the two or more of the EL devices are driven again in at least one remaining sub-frame, or at least two of the two or more EL devices are concurrently driven in the at least one remaining subframe.  
      The at least one remaining sub-frame is arbitrarily selected from a plurality of sub-frames.  
      According to another embodiment, the present invention is directed to a flat panel display having a pixel circuit described according to any of the above-embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art via a description of exemplary embodiments and with reference to the attached drawings in which:  
       FIG. 1  is a block diagram of a conventional display device according to the prior art;  
       FIG. 2  is a schematic diagram of non-self compensation circuits in a conventional display device according to the prior art;  
       FIG. 3  is a schematic diagram of self compensation circuits in a conventional display device according to the prior art;  
       FIG. 4  is a timing graph of a pixel driving method in a conventional display device according to the prior art;  
       FIG. 5  is a block diagram of a display device according to an exemplary embodiment of the present invention;  
       FIG. 6  is a schematic diagram illustrating a pixel circuit of a display device according to one embodiment of the present invention; and  
       FIG. 7  is a timing graph of a pixel driving method of a display device according to one embodiment of the present invention. 
    
    
      The following is an explanation of some of the reference numbers in the drawings: 
           100 : data driver      200 : scan driver      300 : sequential control part      311 R: red emission control line      311 G: green emitting control line      311 B: blue emission control line      400 : pixel part      410 : pixel      420 : compensation circuit      431 : first sequential controller      432 : second sequential controller      433 : third sequential controller        

     DETAILED DESCRIPTION  
       FIG. 5  is a block diagram of an organic electroluminescent display device according to an exemplary embodiment of the present invention.  
      The organic electroluminescent display device illustrated in  FIG. 5  includes data driver  100 , scan driver  200 , sequential control part  300  and pixel part  400 . Pixel part  400  includes a plurality of gate lines  2101 - 210   n  to which scan signals S 1 -Sm are supplied from the scan driver  200 , a plurality of data lines  1111 - 111   n  to which data signals D 1 -Dm are supplied from the data driver  100 , and a plurality of emission control lines  311 - 31   m  to which emission control signals EC_R,G,B 1 -EC_R,G,Bm are supplied from the sequential control part  300 .  
      The pixel part  400  further includes a plurality of pixels P 11 -Pmn arranged in a matrix shape and connected to their respective gate lines  2101 - 210   m , data lines  1111 - 111   n , and emission control lines  311 - 31   m.    
      According to the illustrated embodiment, pixel P 11  is connected to gate line  2101  for providing scan signal S 1 , to data line  1111  for providing data signal D 1 , and to emission control line  311  for outputting a first emission control signal EC_R, G, B 1 .  
      In this manner, scan signals S 1 , S 2 , S 3 , . . . , Sm are applied to the respective pixels P 11 -Pmn through corresponding gate lines  2101 - 210   m , red, green and blue data signals DR 1 -DRm, DG 1 -DGm, DB 1 -DBm are sequentially transmitted to the pixels P 11 -Pmn through corresponding data lines  1111 - 111   n , and corresponding red, green and blue emission control signals EC_R, G, B are sequentially transmitted to pixels P 11 -Pmn through corresponding emission control lines  311 - 31   m . Therefore, whenever corresponding scan signals S 1 -Sm are applied to respective pixels P 11 -Pmn, corresponding red, green and blue data signals DR 1 -DRm, DG 1 -DGm, DB 1 -DBm are sequentially transmitted to pixels P 11 -Pmn, and red, green and blue EL devices R′, G′, B′ are sequentially driven according to the red, green and blue emission control signals EC_R, G, B to sequentially emit lights corresponding to the red, green and blue data signals DR 1 -DRm, DG 1 -DGm, DB 1 -DBm.  
      The sequential control part  300  outputs emission control signals EC_R, G, B to pixels P 1 -Pmn so that the sub-frames are sequentially driven to display a certain color, that is, to display an image during a frame by dividing the frame into, for example, three sub-frames and dividing each of the sub-frames into a data charging section in which the data signals DR 1 -DRm, DG 1 -DGm, DB 1 -DBm are stored and associating in emission period during which the red, green and blue EL devices R′, G′, B′ included in pixels P 11 -Pmn are emitted.  
      For example, one frame is divided into three or more of sub-frames so that respective emitting devices R′, G′, B′ are sequentially driven for each of the sub-frames within the frame. According to this example, either one device out of the emitting devices R′, G′, B′ is driven, or at least two emitting devices are concurrently driven in at least one remaining sub-frame so as to control brightness. The at least one remaining sub-frame is arbitrarily selected from a plurality of sub-frames.  
      Although the emitting devices are described as an example of an organic (EL) device in one embodiment of the present invention, any one of field emission display (FED), liquid crystal display (LCD), or organic EL devices may be adopted in other embodiments of the invention.  
       FIG. 6  is a schematic diagram of a pixel circuit of pixel  410  of a display device according to one embodiment of the present invention.  
      The illustrated pixel  410  includes a compensation circuit  420  including data line  1111  to which a source of data is connected, gate line  2101  to which a gate is connected, and capacitor (not shown) for storing a data signal transmitted from data line  1111 . The pixel  410  further includes a thin film transistor M 1 ′ connected to compensation circuit  420  to output a driving signal corresponding to the data signal, and sequential controllers  431 ,  432 ,  433  commonly connected to thin film transistor M 1 ″. A red EL device R′ is connected to sequential controller  431 , green EL device G′ is connected to sequential controller  432 , and blue EL device B′ is connected to the sequential controller  433 . The compensation circuit  420  includes self compensation circuits or non-self compensation circuits. That is, either the self compensation circuits or non-self compensation circuits may be applied to the display device according to one embodiment of the present invention.  
      According to one embodiment, each pixel  410  in the display device of  FIG. 5  includes unit pixels in such a manner that red, green and blue EL devices R′, G′, B′ included in each unit pixel are commonly connected to driving device M 1 ′, and red, green and blue EL devices R′, G′, B′ are sequentially controlled through their respective sequential controllers  431 ,  432 ,  433 .  
      The sequential controllers  431 ,  432 ,  433  divide a particular frame for displaying an image in the pixel  410 , into at least two or more, or at least three or more, sub-frames. The divided sub-frames are driven during each data charging period and emission period.  
      In other words, if a switching thin film transistor (not shown) included in the compensation circuit  420  is turned on according to a scan signal transmitted through gate line  2101 , red, green and blue data DR 1 -DRm, DG 1 -DGm, DB 1 -DBm transmitted through data line  1111  is stored in a capacitor (not shown) included in the compensation circuit  420 .  
      Compensation circuit  420  outputs a voltage corresponding to a threshold voltage of thin film transistor M 1 ′ to the capacitor. Therefore, the data signal and a compensation voltage for compensating the threshold voltage of thin film transistor M 1 ′ are stored in the capacitor.  
      The sequential control part  300  outputs respective emission control signals EC_R, G, B to sequential controllers  431 ,  432 ,  433  so that the respective emission control signals EC_R, G, B are turned off during a data charging period when data is stored in the capacitor. The sequential controllers  431 ,  432 ,  433  are turned off to prevent driving signals from being applied to the respective emitting devices R′, G′, B′ during the data charging period. That is, a particular frame for displaying an image on the display device is divided into a plurality of sub-frames. At least one or more of the emitting devices are sequentially emitted per sub-frame, and the sub-frames are divided into a data charging period and an emission period. Transmission of the driving signals to the respective emission devices is blocked during the data charging period according to emission control of the sequential controllers  431 ,  432 ,  433 , and data of emitting devices R′ G′ B′ is stored in the capacitor.  
      Afterwards, if the data charging period has expired, the sequential control part  300  outputs an on signal to any one of the sequential controllers  431 ,  432 ,  433 . In response, the data signal stored in the capacitor is transmitted to thin film transistor M 1 ′ and thin film transistor M 1 ′ outputs a driving signal corresponding to an applied data signal to start the emission period.  
      At least any one or more of emitting devices of the red, green and blue EL devices R′, G′, B′ are sequentially emitted in the respective sub-frames of a frame in such a way that at least any one or more of the emitting devices are turned off during a data charging period when the sequential controllers  431 ,  432 ,  433  are turned off, and the emitting devices are emitted during an emission period when the sequential controllers  431 ,  432 ,  433  are turned on.  
       FIG. 7  is a timing graph of a pixel driving method of a display device according to one embodiment of the present invention.  
      First, if scan signal S 1  is applied to gate line  2101  from scan driver  200  during a first sub-frame of a frame, gate line  2101  is driven, and red data signals DR 1 -DRn transmitted from data driver  100  as data signals D 1 -Dm are stored in a capacitor in pixels P 11 -P 1   n . Additionally, sequential control part  300  impresses off control signals to red, green and blue EL devices R′, G′, B′ of pixels P 11 -P 1   n  connected to gate line  2101  through a red emission control line  311 R so that sequential controllers  431 ,  432 ,  433  are turned off during a data charging period when the data signals DR 1 -DRn are stored in the capacitor. Therefore, red, green and blue EL devices R′, G′, B′ connected to sequential controllers  431 ,  432 ,  433  are turned off during a data charging period TR 1  since sequential controllers  431 ,  432 ,  433  are turned off according to emission control signals EC_R 1 , EC_G 1 , EC_B 1  applied to sequential controllers  431 ,  432 ,  433 .  
      After a certain period of time, the sequential control part  300  outputs emission control signal EC_R 1  to sequential controller  431  so that sequential controller  431  is turned on, data charging period TR 1  is completed, and emission period TR 2  is initiated. The sequential control part  300  impresses off emission control signals EC_G 1 , EC_B 1  to sequential controllers  432 ,  433  so that the green and blue EL devices G′, B′ are turned off during the first sub-frame.  
      Red data DR 1 -DRn stored in the capacitor is transmitted to thin film transistor M 1 ′ which is a driving device, and thin film transistor M 1 ′ transmits a driving current corresponding to the red data DR 1 -DRn to the red EL device R′ through sequential controller  431  so that the red EL device R′ is emitted during emission period TR 2 .  
      If second scan signal S 1  is applied to gate line  2101  during a second sub-frame of the first frame, a data charging period TG 1  of the second sub-frame is started for storing green data signals DG 1 -DGn in the capacitor through the compensation circuit  420  by data lines  1111 - 111   n . Red, green and blue EL devices R′, G′, B′ are turned off during data charging period TG 1  since off control signals are applied to sequential controllers  431 ,  432 ,  433  of pixels P 11 -P 1   n  connected to gate line  2101  through red, green and blue emission control lines  311 R,  311 G,  311 B from the sequential control part  300 .  
      After a certain period of time the sequential control part  300  outputs emission control signal EC_G 1  to sequential controller  432  so that sequential controller  432  is turned on to complete data charging period TG 1  and initiate emission period TG 2 . The sequential control part  300  impresses off emission control signals EC_R 1 , EC_B 1  to sequential controllers  431 ,  433  so that the red and blue EL devices R′, B′ are turned off during the second sub-frame.  
      Green data DG 1 -DGn stored in the capacitor is transmitted to thin film transistor M 1 ′ which is a driving device, and thin film transistor M 1 ′ transmits a driving current corresponding to the green data DG 1 -DGn to the green EL device G′ through the sequential controller  432  so that the green EL device G′ is emitted during emission period TG 2  accordingly.  
      If third scan signal S 1  is applied to gate line  2101  during a third sub-frame of the first frame, a data charging period TB 1  of the third sub-frame is started for storing blue data signals DB 1 -DBn in the capacitor through thin film transistor M 1 ′ by data lines  1111 - 111   n . Red, green, and blue EL devices R′, G′, B′ are turned off during data charging period TB 1  since off control signals are applied to sequential controllers  431 ,  432 ,  433  of pixels P 11 -P 1   n  connected to gate line  2101  through red, green, and blue emission control lines  311 R,  311 G,  311 B from the sequential control part  300 .  
      After a certain period of time, the sequential control part  300  outputs emission control signal EC_B 1  to sequential controller  433  so that sequential controller  433  is turned on to complete data charging period TB 1  and initiate emission period TB 2 . The sequential control part  300  impresses off emission control signals EC_R 1 , EC_G 1  to the sequential controllers  431 ,  432  so that the red and green EL devices R′, G′ are turned off during the third sub-frame.  
      Blue data DB 1 -DBn stored in the capacitor is transmitted to thin film transistor M 2 ′, and thin film transistor M 2 ′ transmits a driving current corresponding to the blue data DB 1 -DBn to the blue EL device B′ through sequential controller  433  so that the blue EL device B′ is emitted during emission period TB 2  accordingly.  
      Subsequently, if scan signal S 2  is applied to gate line  2102  for each sub-frame of a frame, red, green and blue data signals DR 1 -DRn, DG 1 -DGn, DB 1 -DBn are sequentially applied to data lines  1111 - 111   n , and emission control signals EC_R 2 , EC_G 2 , EC_B 2  for sequentially controlling red, green and blue EL devices R′, G′, B′ of pixels P 21 -P 2   n  connected to gate line  2102  through emission control lines  311 R,  311 G,  311 B from the sequential control part  300  during data charging periods TR 1 , TG 1 , TB 1  and emission periods TR 2 , TG 2 , TB 2  are sequentially transmitted to sequential controllers  431 ,  432 ,  433 . Therefore, the respective sequential controllers  431 ,  432 ,  433  are sequentially turned on to sequentially transmit driving current corresponding to the red, green and blue data signals DR 1 -DRn, DG 1 -DGn, DB 1 -DBn to the red, green and blue EL devices R′, G′, B′ so that the red, green and blue EL devices R′, G′, B′ are driven.  
      If scan signal is applied to m gate lines  2101 - 210   m  per sub-frame of a frame by repeating the foregoing action, red, green and blue data signals DR 1  DRn, DG 1 -DGn, DB 1 -DBn are sequentially applied to data lines  1111 - 111   n , and emission control signals EC_Rm, EC_Gm, EC_Bm for sequentially controlling red, green and blue EL devices R′, G′, B′ of pixels Pm 1 -Pmn connected to the m gate lines  2101 - 210   m  through emission control lines  311 R,  311 G,  311 B from the sequential control part  300  are sequentially generated to the sequential control part  300  by dividing the red, green and blue EL devices R′, G′, B′ into sub-frames during data charging period TR 1 , TG 1 , TB 1  and emission period TR 2 , TG 2 , TB 2 . Accordingly, sequential controllers  431 ,  432 ,  433  are turned on to sequentially transmit driving current corresponding to the red, green and blue data signals DR 1 -DRn, DG 1 -DGn, DB 1 -DBn to the red, green and blue EL devices R′, G′, B′ so that the red, green and blue EL devices R′, G′, B′ are driven.  
      Therefore, according to one embodiment, one frame is divided into three sub-frames, and the red, green and blue EL devices R′, G′, B′ are sequentially driven during the three sub-frames to display an image. The image is displayed as if the red, green and blue EL devices R′, G′, B′ were concurrently driven for a normal display of images since the red, green and blue EL devices R′, G′, B′ are sequentially driven very fast.  
      One embodiment of the present invention enables high density and precision to be obtained since red, green and blue emitting devices are driven in a time-divided manner by sharing a driving device and a switching device. The opening ratio and yield are also improved via a reduction of the number of devices and wirings by enabling the red, green and blue emitting devices to be commonly applied to self compensation and non-self compensation circuits. Additionally, one embodiment of the present invention allows the display of black gradation and improves contrast ratio by driving the red, green and blue emitting devices which are divided per data charging period and emission period.  
      While the invention has been described with reference to certain exemplary embodiments, it will be understood by those skilled in the art that the invention is intended to cover various changes in form and details without departing from the spirit and scope of the invention. Of course, the scope of the invention is to be determined by the appended claims and equivalents thereof.