Patent Publication Number: US-7719497-B2

Title: Current feedback-type AMOLED where sense feedback is sent over the adjacent data line

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates, in general, to flat panel display devices using an organic light emitting diode and, more particularly, to a current feedback-type active matrix organic light emitting diode driving circuit, which uses a current driving line for an adjacent column as a current feedback line, thus limiting the number of pads of a driving integrated circuit to one per column. 
   2. Description of the Related Art 
   An Organic Light Emitting Diode (hereinafter referred to as an ‘OLED’) is considered to be a greatly promising display device, along with a Liquid Crystal Display (LCD) and a Plasma Panel Display (PDP). In particular, an OLED has the advantages of being the thinnest, of being lightweight, and of having excellent color reproducibility. 
   Such an OLED has characteristics indicating that the brightness thereof is adjusted using current, unlike an LCD for adjusting brightness using voltage. 
   Recently, to satisfy demand for a flat panel display having a bigger size, reproducing more colors, and having a higher response rate, there is a tendency to change a flat panel display from a conventional passive matrix-type flat panel display to an active matrix-type flat panel display. 
   The Active Matrix OLED (AMOLED) display is constructed so that a great number of OLEDs is distributed in two dimensions, and respective OLEDs are sequentially accessed using Thin Film Transistors (TFTs) which can be integrated on a glass substrate, thus controlling the current of the OLEDs. 
   A conventional AMOLED display has adopted a method of converting digital graphic data, which is input for each pixel, into analog voltage through digital-analog conversion, applying the analog voltage as a voltage between the gate and source of a driving TFT connected in series with a corresponding OLED, and maintaining the voltage using a storage capacitor. 
   This method is problematic in that it is very difficult to maintain the current, and moreover, the brightness, of the OLED uniform, due to the non-uniformity of TFTs manufactured using an amorphous silicone (a-Si) or poly-silicone (p-Si) based process. 
   In order to solve the problem of such a voltage driving method, a pixel structure using a current source or a current mirror has been proposed. 
   A pixel in such a current driving method is advantageous in that it not only copes with the basic characteristics of an OLED exhibiting brightness proportional to current, but also uses current as an input, thus the adjustment of uniform brightness is possible in spite of the non-uniformity of driving TFTs. 
   However, such a driving method is problematic in that a lot of time is required until the current of the OLED becomes stable when a low current is driven. This problem becomes more serious as the size of a panel increases, and as the parasitic resistance and capacitance of lines constituting a pixel increase, thus it is well known that the use of such a current driving scheme is very difficult in a large-sized panel. 
     FIG. 1  is a circuit diagram showing an example of a current feedback OLED driving circuit, in which the above-described voltage driving and current driving are appropriately combined with each other (U.S. Pat. No. 6,433,488). 
   The operation of this driving circuit is described in brief below. 
   First, in a pixel circuit, a driving TFT T 1  is connected in series with the OLED, and switching TFTs T 2  to T 4  are provided. 
   If a scan signal Scan becomes high and a specific pixel is selected, the TFTs T 2  and T 3  are turned on, and OLED current is programmed. 
   The time for which a single pixel is selected is determined by the size of a panel and the number of frames per second. 
   If the scan time for a specific pixel is terminated, the scan signal selects a subsequent pixel, the TFTs T 2  and T 3  are turned off, and the TFT T 4  is turned on, so that previously programmed OLED current flows from a power source Vs until a subsequent programming time arrives. 
   The driving circuit part of  FIG. 1  includes a current mirror composed of PMOS transistors P 1  and P 2  for mirroring reference current Iref, which is determined using a circuit (not shown) for converting digital graphic data into current, a current mirror composed of PMOS transistors P 3  and P 4  for mirroring current I OLED , which flows through the OLED, a current comparator composed of NMOS transistors N 1  and N 2  for comparing the two currents with each other, and an amplifier N 3  for amplifying the result of current comparison. 
   If I OLED &lt;Iref when the scan signal is high, that is, in a programming time, the driving circuit is operated so that the output of the current comparator, that is, the voltage at the drain of the transistor N 2 , decreases, the output of the driving circuit, that is, the voltage at the drain of the transistor N 3 , increases, and the voltage at the gate of the pixel driving TFT T 1  increases, thus the OLED current increases. 
   In contrast, if I OLED &gt;Iref, the driving circuit is operated so that voltage at the gate of the driving TFT T 1  decreases, thus the OLED current decreases. The object of the circuit is to operate such that I OLED =Iref is satisfied through such a negative feedback operation. 
   However, this circuit includes two lines for connecting the driving circuit to the pixel circuit. That is, the lines are the data line (Data line) and scan line (Sense line) of  FIG. 1 . For the two lines, the driver IC requires two pads per column (channel). 
   Recently, there is a tendency for the width of each column driver circuit to become less than that of the pad in order to reduce the cost of a driver IC, thus the width of the pad determines the actual area of the driving circuit. 
   Therefore, when two pads are used in a single column driver, as shown in the circuit of  FIG. 1 , the area of the driver IC increases, thus greatly decreasing price competitiveness. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a current feedback-type AMOLED driving circuit, in which a single data line is provided per column, two adjacent columns are paired, and an odd-numbered column and an even-numbered column are temporally separately driven to program current so that, if an odd-numbered column is driven, a data line for an even-numbered column is used as a current feedback line for the odd-numbered column, whereas, if an even-numbered column is driven, a data line for an odd-numbered column is used as a current feedback line for the even-numbered column, thus limiting the number of pads of the driver IC to one per column, and consequently improving price competitiveness. 
   In order to accomplish the above object, the present invention provides a current feedback-type Active Matrix Organic Light Emitting Diode (AMOLED) driving circuit in a current feedback-type AMOLED flat panel display device, comprising a plurality of pixel circuits each having a data terminal for receiving a pixel current command, and a sense terminal for transmitting pixel current to a driver Integrated Circuit (IC); and a plurality of data lines provided such that a single data line is provided for a single column formed by a plurality of pixel circuits, thus data terminals of the pixel circuits, forming the column, are connected to the data line, wherein the AMOLED driving circuit is constructed such that two columns are paired, sense terminals of pixel circuits, forming a first column of the two columns, are connected to a data line for a second column, and sense terminals of pixel circuits, forming the second column, are connected to the data line for the first column, so that the first and second columns are temporally separately driven to program current, and wherein the AMOLED driving circuit is operated such that, when the first column is driven, the data line for the second column is used as a current feedback line for the first column, and when the second column is driven, the data line for the first column is used as a current feedback line for the second column. 
   Preferably, the two columns may be adjacent columns or columns for realizing the same color. 
   Preferably, the current feedback-type AMOLED driving circuit may further comprise a switching unit between the driver IC and the data lines for the two columns, the switching unit connecting a data line for a column, to which current is to be programmed, to a data terminal of the driver IC, and connecting a data line, to be used as a feedback line, to a sense terminal of the driver IC, thus alternately connecting the data lines to the driver IC depending on functions of paired data lines. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a circuit diagram showing a conventional current feedback-type AMOLED driving circuit; 
       FIG. 2  is a circuit diagram showing a current feedback-type AMOLED driving circuit according to the present invention; 
       FIG. 3  is a timing diagram of the driving circuit according to the present invention; 
       FIGS. 4A to 4D  are circuit diagrams showing various embodiments of a pixel circuit used in the driving circuit of  FIG. 2 ; 
       FIG. 5  is a circuit diagram showing a current feedback-type AMOLED driving circuit according to another embodiment of the present invention; 
       FIGS. 6A to 6E  are circuit diagrams showing various embodiments of a pixel circuit used in the driving circuit of  FIG. 5 ; and 
       FIGS. 7 and 8  are circuit diagrams showing a current feedback-type AMOLED driving circuit according to other embodiments of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. However, the following embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. 
     FIG. 2  is a circuit diagram showing a current feedback-type AMOLED driving circuit according to the present invention. 
   As shown in the drawing, column drivers  100  and  200  are connected to pixel circuits  100   a - 1 ,  100   a - 2 ,  100   b - 1 ,  100   b - 2 ,  200   a - 1 ,  200   a - 2 ,  200   b - 1 , and  200   b - 2 , each having a data terminal Data for receiving a pixel current command, and a sense terminal Sense, which is an output terminal for transmitting pixel current to the column driver  100  or  200 , through data lines Data line 1  to Data line 4 . 
   In this case, the pixel circuits  100   a - 1  and  100   a - 2 , forming an odd-numbered column, and the pixel circuits  100   b - 1  and  100   b - 2 , forming an even-numbered column, can be connected to the data terminal Data and the sense terminal Sense of the column driver  100  through a single data line Data line 1  and a single data line Data line 2 , respectively. 
   Further, the driving circuit is constructed so that a switching unit  100 - 1 , composed of a plurality of switches SW 11  to SW 14 , is interposed between the data line Data line 1  for connecting the column driver  100  to the pixel circuits  100   a - 1  and  100   a - 2 , forming an odd-numbered column, and the data line Data line 2  for connecting the column driver  100  to the pixel circuits  100   b - i  and  100   b - 2 , forming an even-numbered column. Accordingly, when the odd-numbered column is driven, the data line Data line 2  for the even-numbered column is used as a sense line (or current feedback line) for the odd-numbered column, whereas, when the even-numbered column is driven, the data line Data line 1  for the odd-numbered column is used as a sense line for the even-numbered column. 
   Similar to this, the column driver  200  is constructed so that pixel circuits  200   a - 1  and  200   a - 2 , forming an odd-numbered column, and the pixel circuits  200   b - 1  and  200   b - 2 , forming an even-numbered column, can be connected to the data terminal Data and the sense terminal Sense of the column driver  200  through a single data line Data line 3  and a single data line Data line 4 , respectively. 
   Further, the driving circuit is constructed so that a switching unit  200 - 1  composed of a plurality of switches SW 11  to SW 14  is interposed between the data line Data line 3  for connecting the column driver  200  to the pixel circuits  200   a - 1  and  200   a - 2 , forming an odd-numbered column, and the data line Data line 4  for connecting the column driver  200  to the pixel circuits  200   b - 1  and  200   b - 2 , forming an even-numbered column. Accordingly, when the odd-numbered column is driven, the data line Data line 4  for the even-numbered column is used as a sense line for the odd-numbered column, whereas, when the even-numbered column is driven, the data line Data line 3  for the odd-numbered column is used as a sense line for the even-numbered column. 
   In the above description, only two column drivers  100  and  200  are described, but it is apparent that the number of column drivers can be expanded, and that the number of pixel circuits can also be expanded. 
   The present invention having the above construction is described with reference to the timing diagram of  FIG. 3 . 
   Each of the column drivers  100  and  200  is a circuit for receiving digital data corresponding to graphic data, and driving a selected pixel using a current value corresponding to the graphic data, and is a current feedback-type AMOLED driving circuit. Each of the column drivers  100  and  200  applies a current command corresponding to input data to a pixel through the data terminal Data, and receives the current of the pixel as a feedback input through the sense terminal Sense, thus the pixel current is driven to a value equal to the input current value. 
   Each of the pixel circuits  100   a - 1 ,  100   a - 2 ,  100   b - 1 ,  100   b - 2 ,  200   a - 1 ,  200   a - 2 ,  200   b - 1 , and  200   b - 2 , forming odd-numbered and even-numbered columns, receives a current command from the column driver  100  or  200 , which is a driver circuit, through the data terminal Data thereof, and transmits current, currently flowing through a pixel, to the column driver  100  or  200  through the sense terminal Sense thereof. 
   Further, if a high signal is externally input to the program terminal Program of each of the pixel circuits  100   a - 1 ,  100   a - 2 ,  100   b - 1 ,  100   b - 2 ,  200   a - 1 ,  200   a - 2 ,  200   b - 1  and  200   b - 2  for receiving a current program control signal, desired current is programmed through the column driver  100  or  200 . If a high signal is input to an illumination terminal Illumination for receiving an illumination control signal, light having a certain brightness is emitted while previously programmed current continuously flows through the pixel circuit. Current flows into the pixel circuit from a power terminal VDD, and flows out of the pixel circuit through a ground terminal GND. 
   Meanwhile, in the case where a row signal ROWk, which is a row select signal, becomes high, and current is programmed to a corresponding row (k-th row), if a control signal ODD, required to select a pixel in an odd-numbered column, is high, a pixel in an odd-numbered column is selected, whereas, if a control signal EVEN, required to select a pixel in an even-numbered column, is high, a pixel in an even-numbered column is selected. In  FIG. 2 , character*in ROWk*ODD denotes a logical product. 
   In relation to this operation, the pixel circuits  100   a - 1 ,  100   a - 2 ,  100   b - 1  and  100   b - 2 , which are connected to the column driver  100  through the data lines Data line 1  and Data line 2 , and form odd-numbered and even-numbered columns, are described as an example. The pixel circuits  200   a - 1 ,  200   a - 2 ,  200   b - 1  and  200   b - 2 , which are connected to the column driver  200  through the data lines Data line 3  and Data line 4  and form odd-numbered and even-numbered columns, are also operated using the same method. 
   Case where a Row Signal ROW 1 , which is a Row Select Signal, is High 
   First, if a control signal ODD required to select a pixel in an odd-numbered column is high, an odd-numbered data line Data line 1  connects the data input of the data terminal Data of the pixel circuit  100   a - 1  in an odd-numbered column to the data output of the data terminal Data of the column driver  100  through the switch SW 11  of the switching unit  100 - 1 . 
   Further, the even-numbered data line Data line 2  connects the sense output of the sense terminal Sense of the pixel circuit  100   a - 1  in an odd-numbered column to the sense input of the sense terminal Sense of the column driver  100  through the switch SW 12  of the switching unit  100 - 1 . 
   Then, if a control signal EVEN, required to select a pixel in an even-numbered column, is high, the even-numbered data line Data line 2  connects the data input of the data terminal Data of the pixel circuit  100   b - 1  in an even-numbered column to the data output of the data terminal Data of the column driver  100  through the switch SW 13  of the switching unit  100 - 1 . 
   Further, the odd-numbered data line Data line 1  connects the sense output of the sense terminal Sense of the pixel circuit  100   a - 1  in the odd-numbered column to the sense input of the sense terminal Sense of the column driver  100  through the switch SWl 4  of the switching unit  100 - 1 . 
   If the row signal ROW 1 , that is, the row select signal, is high, the above procedure is simultaneously performed on all pairs of odd-numbered and even-numbered pixels  200   a - 1  and  200   b - 1 , etc. connected to the first row. If a row signal ROW 2  becomes high, the procedure is repeated on all pairs of odd-numbered and even-numbered pixels connected to a second row. 
   If one of two adjacent columns uses a data line for the other column as a feedback line or sense line of pixel current in turn in this way, the current feedback-type AMOLED driving circuit can be implemented while a single pad per column of the driver IC is maintained. 
     FIGS. 4A to 4D  are circuit diagrams showing various embodiments of the pixel circuit of  FIG. 3 . 
     FIG. 4A  illustrates an embodiment in which the source terminal of a driving transistor T 11  is connected to the anode terminal of an OLED, the cathode terminal of which is connected to ground, the gate terminal and the drain terminal of the driving transistor T 11  are respectively connected to the source terminals of N-type switching transistors T 12  and T 13 , which are each turned on when a current program control signal received through a program terminal Program is high, and the drain terminal of the transistor T 13  is connected to the sense terminal Sense. 
   Further, the drain terminal of the driving transistor T 11  is connected to the source terminal of an N-type switching transistor T 14 , which is turned on to enable the flow of current from a power terminal VDD when an illumination control signal, input from an illumination terminal Illumination for receiving a signal operating opposite the signal input to the program terminal Program, is high. A storage capacitor Cs is connected in parallel between the gate terminal of the driving transistor T 11  and the cathode terminal of the OLED. This structure is described using the pixel circuit  100   a - 1  as an example. 
   First, when a current program control signal input from the program terminal Program is high, the data output of the driver IC, that is, the column driver  100 , is applied to the gate of the driving transistor T 11  through the data line Data Line 1  and the data terminal Data, and drain current of the driving transistor T 11  is transferred to the column driver  100  as a sense input through the data line Data Line 2 . 
   If current programming is terminated, the gate voltage of the driving transistor T 11  is stored and maintained in the storage capacitor Cs, and pixel current constantly flows from the power terminal VDD until subsequent programming starts. 
     FIGS. 4B to 4D  illustrates embodiments in which the location of an OLED is changed, unlike the embodiment of  FIG. 4A .  FIG. 4B  illustrates a structure in which the cathode terminal of the OLED is connected to the drain terminal of a driving transistor T 11 , and the anode terminal of the OLED is connected to the source terminals of transistors T 13  and T 14 .  FIG. 4C  illustrates a structure in which the cathode of an OLED is connected to the drain terminal of the transistor T 14 , and the anode of the OLED is connected to a power terminal VDD.  FIG. 4D  illustrates a structure in which the cathode of an OLED is connected both to the drain terminal of the driving transistor T 11  and the source terminal of the transistor T 13 , and the anode of the OLED is connected to the source terminal of the transistor T 14 . The operations thereof can be understood from  FIG. 4A , so a detailed description thereof is omitted. 
     FIG. 5  is a circuit diagram showing a current feedback-type AMOLED driving circuit according to another embodiment of the present invention, and shows the case where an illumination terminal Illumination is not required, unlike the embodiment of  FIG. 2 . 
   The circuit of  FIG. 5  is operated so that pixel circuits  100   a - 1 ,  100   a - 2 ,  100   b - 1 ,  100   b - 2 ,  200   a - 1 ,  200   a - 2 ,  200   b - 1 , and  200   b - 2  in corresponding odd-numbered columns and even-numbered columns are operated in response to a control signal ROW 1 *ODD or ROW 2 *ODD, required to select a pixel in an odd-numbered column, and a control signal ROW 1 *EVEN or ROW 2 *EVEN, required to select a pixel in an even-numbered column in the embodiment of  FIG. 2 . This operation is the same as that of the embodiment of  FIG. 2 , so a detailed description thereof is omitted. 
     FIGS. 6A to 6E  are circuit diagrams showing various embodiments of the pixel circuit of  FIG. 5 , and shows the case where an illumination terminal Illumination for receiving an illumination control signal is not necessary, unlike the case of  FIG. 4 . 
     FIG. 6A  illustrates a structure in which the anode of an OLED, the cathode of which is connected to the ground, is connected to the source terminal of a driving transistor T 11 , the gate terminal and the drain terminal of the driving transistor T 11  are respectively connected to the source terminals of N-type switching transistors T 12  and T 13 , which are each turned on when a current program control signal input from a program terminal Program is high, and the drain terminal of the transistor T 13  is connected to a sense terminal Sense. 
   Further, the pixel circuit of  FIG. 6A  includes a P-type switching transistor T 14 , the source terminal of which is connected to a power terminal VDD, the drain terminal of which is connected both to the drain terminal of the driving transistor T 11  and to the source terminal of the transistor T 13 , and the gate terminal of which is connected to the program terminal Program to receive the current program control signal therefrom, and which is operated to be turned on when the current program control signal is low. A storage capacitor Cs is connected in parallel between the gate terminal of the driving transistor T 11  and the cathode terminal of the OLED. 
   This structure is only different from the structure of  FIG. 4A  in that, since the gate terminal of the transistor T 14  is connected to the program terminal Program, the circuit is operated in response to the current program control signal received from the program terminal Program. That is, since the transistor T 14  is a P-type transistor, the transistor T 14  is turned off when the transistors T 12  and T 13  are turned on, and is turned on when the transistors T 12  and T 13  are turned off, so that pixel current can constantly flow from the power terminal VDD until subsequent programming starts. 
   Further,  FIG. 6B  to  FIG. 6D  illustrate structures in which the location of an OLED is changed, unlike the structure of  FIG. 6A .  FIG. 6B  illustrates a structure in which the cathode of an OLED is connected to the drain terminal of a driving transistor T 11 , and the anode of the OLED is connected both to the drain terminal of a transistor T 14  and to the source terminal of a transistor T 13 .  FIG. 6C  illustrates a structure in which the cathode of the OLED is connected to the source terminal of the transistor T 14 , and the anode of the OLED is connected to a power terminal VDD.  FIG. 6D  illustrates a structure in which the cathode of the OLED is connected both to the drain terminal of the driving transistor T 11  and to the source terminal of the transistor T 13 , and the anode of the OLED is connected to the drain terminal of the transistor T 14 . The operations thereof can be understood from  FIG. 6A , so a detailed description thereof is omitted. 
   Further,  FIG. 6E  illustrates the case where the transistor T 14  is not included, unlike the cases of  FIGS. 6A to 6D , and shows a structure in which the transistor T 14  of  FIGS. 6A to 6D  is not provided, and the cathode of the OLED is connected both to the drain terminal of the driving transistor T 11  and to the source terminal of the transistor T 13 , and the anode of the OLED is connected to the power terminal VDD. 
   In this structure, voltage output from the sense terminal Sense of the column driver circuit is the voltage at the cathode of the OLED during the programming of pixel current. The structure of  FIG. 6E  suitably controls such a voltage, thus preventing the OLED from being turned on during the programming operation. In this way, since one TFT switch can be omitted, the aspect ratio of the OLED display can be improved. 
     FIG. 7  is a circuit diagram showing a current feedback-type AMOLED driving circuit according to a further embodiment of the present invention, and shows the embodiment in which pixels having the same color are paired, unlike the embodiment of  FIG. 2 . 
   As shown in  FIG. 7 , the circuit has a structure in which two red columns formed by a plurality of pixel circuits Red-a 1 , Red-a 2 , Red-b 1 , and Red-b 2 , which realize a red color, are connected to a single red column driver  100 R through a single data line Data Line 1  and a single data line Data Line 4 , respectively, two green columns formed by a plurality of pixel circuits Green-a 1 , Green-a 2 , Green-b 1 , and Green-b 2 , which realize a green color, are connected to a single green column driver  200 G through a single data line Data Line 2  and a single data line Data Line 5 , respectively, and two blue columns formed by a plurality of pixel circuits Blue-a 1 , Blue-a 2 , Blue-b 1 , and Blue-b 2 , which realize a blue color, are connected to a single blue column driver  300 B through a single data line Data Line 3  and a single data line Data Line 6 , respectively. 
   Further, the AMOLED driving circuit is constructed so that the data line Data line 1 , connected to the pixel circuits Red-a 1  and Red-a 2 , forming one side red column of the two red columns, and the data line Data Line 4 , connected to the pixel circuits Red-b 1  and Red-b 2 , forming the other side red column, can be connected to the red column driver  100 R through the switching operation of a switching unit  100 R- 1  composed of a plurality of switches SW 11  to SW 14 , similar to the above embodiment. Accordingly, a data line for a column, to which current is to be programmed, is connected to the data terminal Data of the column driver circuit, and a data line, to be used as a feedback line, is connected to the sense terminal Sense of the column driver circuit, thus the data lines are alternately connected to the column driver circuit depending on the functions of the paired data lines. This operation is equally applied to the green and blue colors. 
   The operation of the AMOLED driving circuit according to the embodiment is the same as that of the embodiment of  FIG. 2 , so a detailed description thereof is omitted. Further, the embodiment of  FIG. 7  can be implemented using the pixel circuit of  FIGS. 4A to 4D . 
     FIG. 8  is a circuit diagram showing yet another embodiment of the present invention, and shows the case where pixels having the same color are paired, similar to the embodiment of  FIG. 7 , but an illumination terminal Illumination for receiving an illumination control signal is not necessary, similar to the embodiment of  FIG. 5 . The detailed operation thereof can be understood from the embodiments of  FIGS. 7 and 5 , so a detailed description thereof is omitted. Further, the embodiment of  FIG. 8  can be implemented using the pixel circuits of  FIG. 6A to 6E . 
   When the columns having the same color are paired, as shown in  FIGS. 7 and 8 , luminance characteristics for the same current differ for different colors, so that an additional correction circuit is not required, thus the area of a driver IC can be reduced, and the manufacturing cost can be decreased. Further, in adjacent columns having the same color, variation in data is small, so high speed driving can be realized. 
   As described above, the present invention provides a current feedback-type AMOLED driving circuit, in which a single data line is provided for each column, two adjacent columns are paired, and an odd-numbered column and an even-numbered column are temporally separately driven so that, if an odd-numbered column is driven, a data line for an even-numbered column is used as a scan line for the odd-numbered column, whereas, if an even-numbered column is driven, a data line for an odd-numbered column is used as a scan line for the even-numbered column, thus limiting the number of pads of a driver IC to one per column, and consequently improving price competitiveness. 
   Further, the AMOLED driving circuit is advantageous in that, when columns having the same color are paired, luminance characteristics for the same current differ for different colors, so that an additional correction circuit is not necessary, thus the area of a driver IC can be reduced and the manufacturing cost can be decreased, and in that, in the case of adjacent columns having the same color, variation in data is small, thus high speed driving is possible. 
   Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.