Abstract:
An electro-luminescence display device including red, green and blue reference gamma generators each having three digital analog converters or more in order to generate a reference gamma voltage of low gray level and a reference gamma voltage of high gray level, and at least one integrated circuit to generate a data signal in use of the reference gamma voltage of low gray level and the reference gamma voltage of high gray level. Each reference gamma generator includes a first digital analog converter to divide a voltage supplied to itself in order to generate i numbers of voltage levels, a second digital analog converter to divide a voltage supplied to itself in order to generate j numbers of voltage levels, and a third digital analog converter to receive two voltage levels from the second digital analog converter and to divides the two received voltage levels into j numbers of voltage levels.

Description:
This application is a divisional of U.S. application Ser. No. 11/049,058, filed on Feb. 3, 2005, now U.S. Pat. No. 7,511,688 which claims the benefit of the Korean Patent Application Nos. P2004-07244, P2004-07247, P2004-07248, and P2004-07249 filed on Feb. 4, 2004. All of these applications are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electro-luminescence display, and more particularly to an electro-luminescence display that is adaptive for reducing its manufacturing cost as well as reducing its process time. 
     2. Description of the Related Art 
     Recently, there have been highlighted various flat panel display devices reduced in weight and bulk that is capable of eliminating disadvantages of a cathode ray tube (CRT). Such flat panel display devices include a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP) and an electro-luminescence (EL) display, etc. 
     The EL display in such display devices is a self-luminous device capable of light-emitting a phosphorous material by a re-combination of electrons with holes. The EL display device is generally classified into an inorganic EL device using the phosphorous material as an inorganic compound and an organic using it as an organic compound. Such an EL display device has an advantage the its response speed is as fast as the cathode ray tube CRT when compared with a passive luminous device that requires a separate light source like that liquid crystal display. The EL display device also has many advantages of a low voltage driving, a self-luminescence, a thin-thickness, a wide viewing angle, a fast response speed and a high contrast, etc. such that it can be highlighted into a post-generation display device. 
       FIG. 1  is a sectional diagram illustrating a general organic EL structure for explanation of light emission principle of an EL display device. The organic EL includes an electron injection layer  4 , an electron carrier layer  6 , a light-emitting layer  8 , a hole carrier layer  10 , a hole injection layer  12  between a cathode  2  and an anode  14 . 
     When a voltage is applied between the anode  14  of a transparent electrode and the cathode  2  of a metal electrode, an electron generated from the cathode  2  moves to the light-emitting layer  8  through the electron injection layer  4  and the electron carrier layer  6 . Also, a hole generated from the anode  14  moves to the light-emitting layer  8  through the hole injection layer  12  and the hole carrier layer  10 . Accordingly, the electrons are collided with the holes at the light-emitting layer  8 , wherein the electrons and the holes are supplied from the electron carrier layer  6  and the hole carrier layer  10 , and the electrons and the holes are recombined to generate light. The generated light is emitted through the anode  14  to display a picture. The light-emission brightness of the EL organic device is not proportional to the voltage flowing in both ends of the device, but it is proportional to a supply current, thus the anode  14  is usually connected to a static current source. 
       FIG. 2A  is a diagram illustrating a general EL display device. 
     Referring to  FIG. 2A , an EL display device includes an EL display panel  20  having EL cells  28  arranged at each intersection of scan electrode lines SL and data electrode lines DL, a scan driver  22  to drive the scan electrode lines SL, a data driver  24  to drive the data electrode lines DL, and a gamma voltage supplier  26  to supply reference gamma voltages to the data driver  24 . 
     Each of the EL cells  28  is selected when a scan pulse is applied to the scan electrode line SL, which is a cathode, to generate a light corresponding to a pixel signal, i.e., data signal or current signal, supplied to the data electrode line DL, which is an anode. Each of the EL cells  28  operates substantially in the same manner as a diode connected between the data electrode line DL and the scan electrode line SL to be equivalent. Accordingly, each of the EL cells  28  supplies a negative scan pulse to the scan electrode line SL, and at the same time applies a positive current according to a data signal to the data electrode line DL, thereby emitting light when a forward voltage is applied. Differently from this, the EL cells  28  included in the unselected scan line do not emit light due to a reverse bias voltage. 
     The scan driver  22  sequentially supplies the negative scan pulse to a plurality of scan electrode lines SL. 
     The data driver  24  includes more than one data integrated circuit  30 . As the EL display panel  20  becomes bigger, the number of data integrated circuits  30 , which form the data driver  24 , is larger. On the other hand, the data driver  24  might be composed of one data integrated circuit  30  as in  FIG. 2B  when the EL display panel  20  is made in a small panel like the display panel of a mobile phone. 
     In this way, the conventional EL display device supplies the current signal, which is proportional to an input data, to each of the EL cells  28  to make the EL cells  28  emit light, thereby displaying a picture. EL cells  28  is composed of an R cell having a red (hereinafter, “R”) phosphorus, a G cell having a green (hereinafter, “G”) phosphorus, and a B cell having a blue (hereinafter, “B”) phosphorus, for materializing color. 
     Each of R, G, B phosphorus&#39;s has different efficiency from each other. In other words, the brightness level of R, G, B cells are different from each other in case that data signals of same level to R, G, B cells. Accordingly, the gamma voltages are set differently from each other by R, G, B in comparison with the same brightness in order to meet white balance. The gamma voltage supplier  26  generates a different reference gamma voltage by R, G, B. 
       FIG. 3  is a circuit diagram illustrating in detail a gamma voltage supplier  26  shown in  FIGS. 2A and 2B . 
     Referring to  FIG. 3 , the prior art gamma voltage supplier  26  includes an R gamma voltage supplier  32 , a G gamma voltage supplier  34 , a B gamma voltage supplier  36  for supplying each of the different reference gamma voltages by R, G, B. 
     The R gamma voltage supplier  32  includes a divided voltage resistors r_R 1 , r_R 2 , r_R 3  connected in series between a supply voltage source VDD and a ground voltage source GND. A divided voltage generated at nodes n 1 , n 2  between the divided voltage resistors r_R 1 , r_R 2 , r_R 3  is supplied to the data driver  24  as a reference gamma voltage. The voltage of the first node n 1  is used as an R reference gamma voltage VH_R of low gray level, and the voltage of the second node n 2  is used as an R reference gamma voltage VL_R of high gray level. 
     The G gamma voltage supplier  34  includes a divided voltage resistors r_G 1 , r_G 2 , r_G 3  connected in series between a supply voltage source VDD and a ground voltage source GND. A divided voltage generated at nodes n 3 , n 4  between the divided voltage resistors r_G 1 , r_G 2 , r_G 3  is supplied to the data driver  24  as a reference gamma voltage. The voltage of the third node n 3  is used as a G reference gamma voltage VH_G of low gray level, and the voltage of the fourth node n 4  is used as a G reference gamma voltage VL_G of high gray level. 
     The B gamma voltage supplier  36  includes a divided voltage resistors r_B 1 , r_B 2 , r_B 3  connected in series between a supply voltage source VDD and a ground voltage source GND. A divided voltage generated at nodes n 5 , n 6  between the divided voltage resistors r_B 1 , r_B 2 , r_B 3  is supplied to the data driver  24  as a reference gamma voltage. The voltage of the fifth node n 5  is used as a G reference gamma voltage VH_B of low gray level, and the voltage of the sixth node n 6  is used as a G reference gamma voltage VL_B of high gray level. 
     In other words, the prior art gamma voltage supplier  26  differently supplies the reference gamma voltage, which corresponds to each of the R cell, the G cell and the B cell, to the data driver  24 . On the other hand, the gamma voltage supplier  26  includes a plurality of the R gamma voltage supplier  32 , the G gamma voltage supplier  34 , and the B gamma voltage supplier  36 , as in  FIG. 3 , so that a light of different brightness could be generated in correspondence to an external environment. For example, the gamma voltage supplier  26  can includes three each of the R gamma voltage supplier  32 , the G gamma voltage supplier  34 , and the B gamma voltage supplier  36  so that three modes of reference gamma voltage could be supplied in correspondence to night, day and the external environment. In this case, the number of total resistors included in the gamma voltage supplier  26  has to increase to  27 . 
     The data integrated circuit  30  divides voltage as much as the gray levels, which are capable of expressing the reference gamma voltage supplied from the gamma voltage supplier  26 , to generate an analog data which corresponds to each gray level. For this, the data integrated circuit  30  includes a shift register  40 , a first latch array  42 , a second latch array  44 , a digital analog converter (hereinafter, referred to as “DAC”), and an output array  48 . 
     The shift register  40  generates a sampling signal to sample data while shifting a start pulse in accordance with a shift clock. 
     The first latch array  42  includes a first R latch part  42   a , a first G latch part  42   b  and a first B latch part  42 C. The first R latch part  42   a  samples an R data in accordance with the sampling signal supplied from the shift register  40  and temporarily stores the R data. The first G latch part  42   b  samples a G data in accordance with the sampling signal supplied from the shift register  40  and temporarily stores the G data. The first B latch part  42 C samples a B data in accordance with the sampling signal supplied from the shift register  40  and temporarily stores the B data. 
     The second latch array  44  supplies the data from the first latch array  42  to the DAC  46  in response to an output enable signal. For this, the second latch array  44  includes a second R latch part  44   a , a second G latch part  44   b  and a second B latch part  44 C. The second R latch part  44   a  supplies the data from the first R latch part  42   a  to the DAC  46  in response to the output enable signal. The second G latch part  44   b  supplies the data from the first G latch part  42   b  to the DAC  46  in response to the output enable signal. The second B latch part  44   c  supplies the data from the first B latch part  42   c  to the DAC  46  in response to the output enable signal. 
     The DAC  46  converts the data from the second latch array  44  into the analog data and outputs the converted data to the output array  48  in use of the reference gamma voltage VH_R, VL_R, VH_G, VL_G, VH_B, VL_B. For this, the DAC  46  includes an R DAC  46   a , a G DAC  46   b  and a B DAC  46   c.    
     The R DAC  46   a  receives the R reference gamma voltage VH_R of low gray level and the R reference gamma voltage VL_R of high gray level from the gamma voltage supplier  26 . And the R DAC  46   a  generates a plurality of gamma voltages in use of the R reference gamma voltage VH_R of low gray level and the R reference gamma voltage VL_R of high gray level. For example, the R DAC  46   a  generates sixty four analog gamma voltages assuming that there is a six bit input data. And the R DAC  46   a  selects the analog gamma voltage corresponding to the digital data from the second R latch part  44   a  as the analog data which is to be supplied to the data line DL. 
     The G DAC  46   b  receives the G reference gamma voltage VH_G of low gray level and the G reference gamma voltage VL_G of high gray level from the gamma voltage supplier  26 . And the G DAC  46   b  generates a plurality of gamma voltages in use of the G reference gamma voltage VH_G of low gray level and the G reference gamma voltage VL_G of high gray level. For example, the G DAC  46   b  generates sixty four analog gamma voltages assuming that there is a six bit input data. And the G DAC  46   b  selects the analog gamma voltage corresponding to the digital data from the second G latch part  44   b  as the analog data which is to be supplied to the data line DL. 
     The B DAC  46   c  receives the B reference gamma voltage VH_B of low gray level and the B reference gamma voltage VL_B of high gray level from the gamma voltage supplier  26 . And the B DAC  46 C generates a plurality of gamma voltages in use of the B reference gamma voltage VH_B of low gray level and the B reference gamma voltage VL_B of high gray level. For example, the B DAC  46   c  generates sixty four analog gamma voltages assuming that there is a six bit input data. And the B DAC  46   c  selects the analog gamma voltage corresponding to the digital data from the second B latch part  44   c  as the analog data which is to be supplied to the data line DL. 
     The output array  48  supplies the analog data supplied from the DAC  46  to the data electrode lines DL. For this, the output array  48  includes a first output part  48   a , a second output part  48   b , a third output part  48   c . A first output part  48   a  supplies the analog data from the R DAC  46   a  to the data electrode lines DL which is for supplying data to the R cells. The second output part  48   b  supplies the analog data from the G DAC  46   b  to the data electrode lines DL which is for supplying data to the G cells. The third output part  48   c  supplies the analog data from the B DAC  46   c  to the data electrode lines DL which is for supplying data to the B cells. 
     As a result, the gamma voltage supplier  26  supplies the reference gamma voltages, which corresponds to the R cell, the G cell and the B cell and are different from each other, to the data driver  24 , and the data driver  24  generates the data signal, which is to be supplied to the R cell, the G cell and the B cell in use of the different reference gamma voltage. 
     And yet, the related art EL display device might have the brightness deviation generated between the EL display panels  20  by the deviation of manufacturing process. In other words, the brightness might be different in the same data in accordance with the EL display panel  20 . In order to reduce such a brightness deviation, in the prior art, the resistance value of the resistors included in the gamma voltage supplier  26  is controlled to reduce the brightness deviation between the EL display panels  20 . However, if the brightness deviation is compensated with the resistance value of the resistors, its process time is lengthened due to the adjustment time required for optimization of the resistance value or the replacement time of the resist, thus it is impossible to compensate the exact brightness deviation only by the adjustment of the resistance value. 
     The data integrated circuit  30  is mounted on a chip on film COF  50  as in  FIG. 5 , the resistors of the gamma voltage supplier  26  are mounted on a flexible printed circuit FPC  52  due to many resistors, which is difficult to be mounted on the COF  50 . Because of many resistors of the gamma voltage supplier  26  like this, it is difficult to secure a margin in designing the FPC. Terminals of one side of the FPC  52  are connected to the COF  50  and terminals of the other side are connected to a printed circuit board PCB (not shown). Due to such FPC  52  and COF  50 , there is a problem that the prior art EL display device has high manufacturing cost due to the FPC  52 , and time is required for aligning the FPC  52  with the COF  50 . 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an electro-luminescence display that is adaptive for reducing its manufacturing cost as well as reducing its process time. 
     In order to achieve these and other objects of the invention, an electro-luminescence display device according to an aspect of the present invention includes a gamma generator to output a reference gamma voltage corresponding to a control data supplied from the outside; and at least one data integrated circuit to receive a data from the outside and to generate a data signal corresponding to the bit number of the data in use of the reference gamma voltage. 
     The gamma generator may include: a red gamma part to generate a red reference gamma voltage so that the data signal to be supplied to a red cell can be generated; a green gamma part to generate a green reference gamma voltage so that the data signal to be supplied to a green cell can be generated; and a blue gamma part to generate a blue reference gamma voltage so that the data signal to be supplied to a blue cell can be generated. 
     Each of the red gamma part, the green gamma part and the blue gamma part may include: a first resist part and a second resist part to divide the voltage of a supply voltage source; a first analog digital converter to divide the divided voltage supplied from the first resist part into a plurality of voltage levels; a second analog digital converter to divide the divided voltage supplied from the second resist part into a plurality of voltage levels; and a register to supply a first control data so that any one voltage can be outputted in the first analog digital converter, as well as to supply a second control data to that any one voltage can be outputted in the second analog digital converter. 
     Each of the first and second resist parts may include three resistors so that the voltage of the supply voltage source can be divided into two voltage values. 
     Bit values of the first and second control data may be set to enable the electro-luminescence display device to display uniform brightness. 
     The gamma generator and the data integrated circuits may be mounted on a chip-on-film COF. 
     The red reference gamma voltage, the green reference gamma voltage, the red reference gamma voltage may be set for a white balance to be balanced in red, green and blue cells. 
     The gamma generator may be integrated in the inside of the data integrated circuit. 
     An electro-luminescence display device according to another aspect of the present invention includes a gamma generation voltage supplier to generate a plurality of gamma generation voltages; a reference gamma generator to generate a plurality of reference gamma voltages in use of the gamma generation voltages; and at least one data integrated circuit to divide the reference gamma voltage into a plurality of voltage levels and to generate a data signal by selecting any one voltage level among the voltage levels in correspondence to a data from the outside. 
     The gamma generation voltage supplier may include: a red gamma generation voltage part to generate a red gamma generation voltage of high gray level and a red gamma generation voltage of low gray level; a green gamma generation voltage part to generate a green gamma generation voltage of high gray level and a green gamma generation voltage of low gray level; and a blue gamma generation voltage part to generate a blue gamma generation voltage of high gray level and a blue gamma generation voltage of low gray level. 
     Each of the red, green and blue gamma generation voltage parts may include: a first divided voltage resistor and a second divided voltage resistor installed between a supply voltage source and a ground voltage source in order to generate the gamma generation voltage of high gray level; and a third divided voltage resistor and a fourth divided voltage resistor installed between the supply voltage source and the ground voltage source in order to generate the gamma generation voltage of low gray level. 
     The reference gamma generator may include: a red reference gamma generator to generate a red reference gamma voltage of high gray level and a red reference gamma voltage of low gray level in use of the red gamma generation voltage of high gray level and the red gamma generation voltage of low gray level; a green reference gamma generator to generate a green reference gamma voltage of high gray level and a green reference gamma voltage of low gray level in use of the green gamma generation voltage of high gray level and the green gamma generation voltage of low gray level; and a blue reference gamma generator to generate a blue reference gamma voltage of high gray level and a blue reference gamma voltage of low gray level in use of the blue gamma generation voltage of high gray level and the blue gamma generation voltage of low gray level. 
     Each of the red, green and blue reference gamma generator may include: a first analog digital converter to receive a first reference voltage that has a higher voltage value than the gamma generation voltage of low gray level and the gamma generation voltage of low gray level, and to divide the received voltage into a plurality of first voltage levels; a second analog digital converter to receive a second reference voltage that has a lower voltage value than the gamma generation voltage of high gray level and the first reference voltage, and to divide the received voltage into a plurality of second voltage levels; and a register to supply a first control data so that any one voltage among the first voltage levels can be outputted in the first analog digital converter, as well as to supply a second control data to that any one voltage among the second voltage levels can be outputted in the second analog digital converter. 
     The number of the second voltage levels voltage-divided at the second analog digital converter may be set to be higher than the number of the first voltage levels voltage-divided at the first analog digital converter. 
     The first and second control data may be set to enable the electro-luminescence display devices to display uniform brightness. 
     The gamma generation voltage supplier may include: a red gamma generation voltage part to generate a red first reference voltage, a red gamma generation voltage of low gray level that has a lower voltage value than the red first reference voltage, a red second reference voltage that has a lower voltage value than the red first reference voltage, and a red gamma generation voltage of high gray level that has a lower voltage value than the red second reference voltage; a green gamma generation voltage part to generate a green first reference voltage, a green gamma generation voltage of low gray level that has a lower voltage value than the green first reference voltage, a green second reference voltage that has a lower voltage value than the green first reference voltage, and a green gamma generation voltage of high gray level that has a lower voltage value than the green second reference voltage; and a blue gamma generation voltage part to generate a blue first reference voltage, a blue gamma generation voltage of low gray level that has a lower voltage value than the blue first reference voltage, a blue second reference voltage that has a lower voltage value than the blue first reference voltage, and a blue gamma generation voltage of high gray level that has a lower voltage value than the blue second reference voltage. 
     Each of the red, green and blue gamma generation voltage parts may include: three first divided voltage resistors installed between a supply voltage source and a ground voltage source in order to generate the first reference voltage and the gamma generation voltage of low gray level; and three second divided voltage resistors installed between the supply voltage source and the ground voltage source in order to generate the second reference voltage and the gamma generation voltage of high gray level. 
     The reference gamma generator may include: a red reference gamma generator to generate a red reference gamma voltage of high gray level and a red reference gamma voltage of low gray level in use of the red first reference voltage, the red gamma generation voltage of low gray level, the red second reference voltage and the red gamma generation voltage of high gray level; a green reference gamma generator to generate a green reference gamma voltage of high gray level and a green reference gamma voltage of low gray level in use of the green first reference voltage, the green gamma generation voltage of low gray level, the green second reference voltage and the green gamma generation voltage of high gray level; and a blue reference gamma generator to generate a blue reference gamma voltage of high gray level and a blue reference gamma voltage of low gray level in use of the blue first reference voltage, the blue gamma generation voltage of low gray level, the blue second reference voltage and the blue gamma generation voltage of high gray level. 
     Each of the red, green and blue reference gamma generators may include: a first analog digital converter to divide the first reference voltage and the gamma generation voltage of low gray level into a plurality of first voltage levels; a second analog digital converter to divide the second reference voltage and the gamma generation voltage of high gray level into a plurality of second voltage levels; and a register to supply a first control data so that any one voltage among the first voltage levels can be outputted in the first analog digital converter, as well as to supply a second control data to that any one voltage among the second voltage levels can be outputted in the second analog digital converter. 
     The number of the second voltage levels voltage-divided at the second analog digital converter may be set to be higher than the number of the first voltage levels voltage-divided at the first analog digital converter. 
     The first and second control data may be set to enable the electro-luminescence display devices to display uniform brightness. 
     The reference gamma generator is integrated in the inside of the data integrated circuit. 
     An electro-luminescence display device according to still another aspect of the present invention may include: a red reference gamma generator, a green reference gamma generator and a blue reference gamma generator each having three digital analog converters or more in order to generate a reference gamma voltage of low gray level and a reference gamma voltage of high gray level; and at least one integrated circuit to generate a data signal in use of the reference gamma voltage of low gray level and the reference gamma voltage of high gray level. 
     Each of the red, green and blue reference gamma generators may include: a first digital analog converter to divide a voltage supplied to itself in order to generate i (i is a natural number) numbers of voltage levels; a second digital analog converter to divide a voltage supplied to itself in order to generate j (j is a smaller natural number than i) numbers of voltage levels; and a third digital analog converter to receive two voltage levels from the second digital analog converter and to divides the two received voltage levels into j numbers of voltage levels. 
     The first digital analog converter may select any one voltage among the i numbers of voltage levels, as the reference gamma voltage of low gray level, to supply the selected voltage to the integrated circuit. 
     The third digital analog converter may select any one voltage among the j numbers of voltage levels generated by itself, as the reference gamma voltage of high gray level, and to supply the selected voltage to the integrated circuit. 
     The second digital analog converter may supply two voltage levels adjacent to each other among the j numbers of voltage levels generated by itself, to the third digital analog converter. 
     Each of the red, green and blue reference gamma generation parts further may include a register storing control data&#39;s that control the output of the first digital analog converter, the second digital analog converter and the third digital analog converter. 
     The control data&#39;s stored at the register may be set to enable the electro-luminescence display devices to display uniform brightness. 
     The red reference gamma generator, the green reference gamma generator and the blue reference gamma generator may be mounted in the inside of the integrated circuit. 
     An electro-luminescence display device according to still another aspect of the present invention may include: a gamma generation voltage supplier to generate a reference gamma voltage of low gray level and a plurality of gamma generation voltages; a reference gamma generator to generate a reference gamma voltage of high gray level in use of the gamma generation voltages; and a data integrated circuit to generate a data signal in use of the reference gamma voltage of low gray level and the reference gamma voltage of high gray level. 
     The gamma generation voltage supplier may include: a red gamma generation voltage supplier to generate a red reference gamma voltage of low gray level so that the data signal to be supplied to a red cell can be generated; a green gamma generation voltage supplier to generate a green reference gamma voltage of low gray level so that the data signal to be supplied to a green cell can be generated; and a blue gamma generation voltage supplier to generate a blue reference gamma voltage of low gray level so that the data signal to be supplied to a blue cell can be generated. 
     Each of the red, green and blue gamma generation voltage supplier may include: a variable resistor to divide a voltage value of a common voltage source to generate the reference gamma voltage of low gray level; and a plurality of divided voltage resistors to divide the reference gamma voltage of low gray level into two different voltage levels from each other to generate the gamma generation voltages. 
     A resistance value of the variable resistor included in each of the red, green and blue gamma generation voltage supplier may be set to be differently. 
     The reference gamma generator may include: a red reference gamma generator to generate a red reference gamma voltage of high gray level so that the data signal to be supplied to a red cell can be generated; a green reference gamma generator to generate a green reference gamma voltage of high gray level so that the data signal to be supplied to a green cell can be generated; and a blue reference gamma generator to generate a blue reference gamma voltage of high gray level so that the data signal to be supplied to a blue cell can be generated. 
     Each of the red, green and blue reference gamma generators may include: a digital analog converter to divide the voltages supplied from the gamma generation voltage supplier into a plurality of voltage levels; and a register storing a control data that enables to output any one voltage among the voltage levels voltage-divided at the digital analog converter. 
     The control data stored at the register may be set to enable the electro-luminescence display device to display uniform brightness. 
     The reference gamma generator may be mounted in the inside of the data integrated circuit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects of the invention will be apparent from the following detailed description of the embodiments of the present invention with reference to the accompanying drawings, in which: 
         FIG. 1  is a sectional diagram illustrating the structure of a general organic electro-luminescence; 
         FIGS. 2A and 2B  are diagrams representing an electro-luminescence display device of the prior art; 
         FIG. 3  is a circuit diagram representing the structure of a gamma voltage supplier shown in  FIGS. 2A and 2B ; 
         FIG. 4  is a diagram representing in detail a data integrated circuit shown in  FIGS. 2A and 2B ; 
         FIG. 5  is a diagram illustrating how to install the gamma voltage supplier and the data integrated circuit shown in FIGS.  2 A and  2 B; 
         FIG. 6  is a diagram representing an electro-luminescence display device according to a first embodiment of the present invention; 
         FIGS. 7A to 7C  are diagrams illustrating the structure of a gamma generator shown in  FIG. 6 ; 
         FIG. 8  is a diagram illustrating how to install the gamma generator and a data integrated circuit shown in  FIG. 6 ; 
         FIG. 9  is a diagram representing an electro-luminescence display device according to a second embodiment of the present invention; 
         FIG. 10  is a diagram representing an electro-luminescence display device according to a third embodiment of the present invention; 
         FIG. 11  is a circuit diagram illustrating in detail a gamma generation voltage supplier shown in  FIG. 10 ; 
         FIG. 12  is a diagram illustrating in detail a reference gamma generator shown in  FIG. 10 ; 
         FIG. 13  is a graph illustrating in brief a brightness change corresponding to a voltage value; 
         FIG. 14  is a circuit diagram illustrating another embodiment of the gamma generation voltage supplier; 
         FIG. 15  is a diagram illustrating an embodiment that the reference gamma generator is integrated in the inside of the data integrated circuit; 
         FIG. 16  is a circuit diagram illustrating still another embodiment of the gamma generation voltage supplier; 
         FIGS. 17A to 17C  are circuit diagrams illustrating still another embodiment of the reference gamma generator; 
         FIG. 18  is a circuit diagram illustrating in detail a second DAC of  FIGS. 17A to 17C ; 
         FIGS. 19A to 19C  are circuit diagrams illustrating another embodiment of the second DAC; 
         FIG. 20  is a diagram for explaining the operation of the second and third DAC&#39;s; 
         FIG. 21  is a diagram illustrating an example that the gamma generation voltage supplier together with the reference gamma generator is built in the data integrated circuit; 
         FIG. 22  is a diagram illustrating an electro-luminescence display device according to a fourth embodiment of the present invention; 
         FIG. 23  is a circuit diagram illustrating in detail a gamma generation voltage supplier shown in  FIG. 22 ; 
         FIGS. 24A to 24C  are diagrams illustrating in detail a reference gamma generator shown in  FIG. 22 ; and 
         FIG. 25  is a diagram illustrating a circuit where the reference gamma generator shown in  FIG. 22  is built in an integrated circuit. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
     Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to  FIGS. 6 to 25 . 
       FIG. 6  is a diagram illustrating an EL display device according to a first embodiment of the present invention. In the embodiment, it is assumed that at least two data integrated circuits  66  are mounted on a data driver  64 . 
     Referring to  FIG. 6 , an EL display device according to a first embodiment of the present invention includes an EL display panel  60  having EL cells  70  arranged at each intersection of scan electrode lines SL and data electrode lines DL, a scan driver  62  to drive the scan electrode lines SL, and a data driver  64  to drive the data electrode lines DL. 
     Each of the EL cells  70  is selected when a scan pulse is applied to the scan electrode line SL to generate the light corresponding to a data signal supplied to the data electrode line DL. In other words, a designated picture is displayed at the EL display panel  60  because the light corresponding to the data signal is generated in each of the EL cells  70 . 
     The scan driver  62  sequentially supplies a scan pulse to a plurality of scan electrode lines SL. 
     The data driver  64  includes a plurality of data integrated circuits  66  and a gamma generator  100 . 
     The data integrated circuits  66 , which is composed as in  FIG. 4 , divides a reference gamma voltage supplied from the gamma generator  100  into a plurality of voltage levels to generate a data signal, and the generated data signal is supplied to the data electrode lines DL. In other words, the data integrated circuits  66  selects the voltage level corresponding to the bit number of data to generate the data signal, and supplies the generated data signal so that the data signal to be synchronized with the scan pulse. 
     The gamma generator  100  supplies the reference gamma voltage to the data integrated circuits  66 . For this, the gamma generator  100  includes an R reference gamma generator  68 R, a G reference gamma generator  68 G, and a B reference gamma generator  68 B. 
     The R reference gamma generator  68 R generates an R reference gamma voltage VH_R of low gray level and an R reference gamma voltage VL_R of high gray level, and supplies them to the data integrated circuits  66 . The G reference gamma generator  68 G generates an G reference gamma voltage VH_G of low gray level and an G reference gamma voltage VL_G of high gray level, and supplies them to the data integrated circuits  66 . The B reference gamma generator  68 B generates an B reference gamma voltage VH_B of low gray level and an B reference gamma voltage VL_B of high gray level, and supplies them to the data integrated circuits  66 . 
     For this, the R reference gamma generator  68 R includes resistance parts  80 ,  82 , DAC&#39;s  84 ,  86 , and registers  88 , as in  FIG. 7A . 
     The resistance parts  80 ,  82  include the first resistance part  80  and the second resistance part  82 . The first resistance part  80  includes divided voltages r_R 1 _H, r_R 2 _H, r_R 3 _H installed between a supply voltage source and a ground voltage source GND. First and second voltages divided by the divided voltage resistors r_R 1 _H, r_R 2 _H, r_R 3 _H are supplied to the DAC  84 . The second resistance part  82  includes divided voltages r_R 1 _L, r_R 2 _L, r_R 3 _L installed between a supply voltage source and a ground voltage source GND. Third and fourth voltages divided by the divided voltage resistors r_R 1 _L, r_R 2 _L, r_R 3 _L are supplied to the DAC  86 . 
     The DAC&#39;s  84 ,  86  include a first DAC  84  and a second DAC  86 . The first DAC  84  divides the first voltage and the second voltage into a plurality of voltage levels. For example, the first and second voltages are divided into 2 i  number of voltage level, if an i (i is a natural number) bit is inputted from a register  88 . And, the first DAC  84  supplies any one voltage of a plurality of voltage levels, which are divided from in correspondence to the bit number of the control data supplied from the register  88 , to the data integrated circuits  66  as the R reference gamma voltage VH_R of low gray level. 
     The second DAC  86  divides the third voltage and the fourth voltage into a plurality of voltage levels. For example, i bit is inputted from the register  88 , the third and fourth voltage is divided into 2 i  numbers of voltage levels. And, the second DAC  86  supplies any one voltage of the voltage levels divided in correspondence to the bit number of the control data supplied from the register  88 , to the data integrated circuits  66  as the R reference gamma voltage VL_R of high gray level. 
     In the register  88 , the control data of i bit is stored to control the output voltage value of each of the first DAC  84  and the second DAC  86 . In other words, the first control data of the register  88  is supplied to the first DAC  84  to control the first DAC  84 . And, the second control data of the register  88  is supplied to the second DAC  86  to control the second DAC  86 . Herein, the bit value of the first and second control data inputted to the register  88  is determined by a user. For example, in the register  88 , it is possible to store the control data value that can compensate the brightness deviation generated between the EL display panels  60 . 
     To described this in detail, when a brightness deviation exists between the EL display panels  60 , a user controls the first and second data value, which are to be stored in the register  88 , to compensate the brightness deviation between the EL display panels  60 . 
     A mode controller (not shown) is installed in an input terminal of the register  88 , and the register  88  receives the first and second control data from the mode controller to control the output values of the first and second DAC&#39;s  84 ,  86 , thus it is possible to control to display a picture of an appropriate brightness that corresponds to an external environment, i.e., day, night, rain, snow and etc. 
     On the other hand, the G gamma generator  68 G and the B gamma generator  68 B are composed as in  FIGS. 7B and 7C  in this invention. The value stored at the register  88  included in the G gamma generator  68 G and the B gamma generator  68 B are set to have the white balance of the R cell, G cell and B cell balanced. The operation process is substantially the same as the foregoing R gamma generator  68 R, thus a detailed description is to be omitted. 
     The gamma generator  100  includes a fewer number of resistors than the gamma voltage supplier  26  of the prior art shown in  FIG. 3 . Accordingly, the gamma generator  100  of the present invention can be mounted on a COF  102  along with the data integrated circuit  66  as shown in  FIG. 8 . In this way, if the gamma generator  100  on the COF  102 , its manufacturing cost can be reduced. 
       FIG. 9  is a diagram illustrating an EL display device according to a second embodiment of the present invention. In the embodiment, it is assumed that one data integrated circuit  200  is mounted on the data driver  64 . In  FIG. 9 , the same composition as  FIG. 6  is to be given the same reference numerals and of which the further description is to be omitted. 
     Referring to  FIG. 9 , the EL display device according to the second embodiment of the present invention includes an EL display panel  60  having EL cells  70  arranged at each intersection of scan electrode lines SL and data electrode lines DL, a scan driver  62  to drive the scan electrode lines SL, and a data driver  64  to drive the data electrode lines DL. 
     Each of the EL cells  70  is selected when a scan pulse is applied to the scan electrode line SL, to generate the light corresponding to a data signal supplied to the data electrode line DL. In other words, because a designated light corresponding to the data signal is generated in each of the EL cells  70 , a designated picture is displayed in the EL display panel  60 . 
     The scan driver  62  sequentially supplies the scan pulse to a plurality of scan electrode lines SL. 
     The data driver  64  includes one data integrated circuit  200 . A reference gamma generator  100  is built in the data integrated circuit  200 . And, the other configuration is made as in  FIG. 4 . 
     The reference gamma generator  100  includes an R reference gamma generator  68 R, a G reference gamma generator  68 G and a B reference gamma generator  68 B. The R reference gamma generator  68 R generates an R reference gamma voltage VH_R of low gray level and an R reference gamma voltage VL_R of high gray level to supply it to an R DAC  200 A. And, the G reference gamma generator  68 G generates a G reference gamma voltage VH_G of low gray level and a G reference gamma voltage VL_G of high gray level to supply it to a G DAC  200 B. And, the B reference gamma generator  68 B generates a B reference gamma voltage VH_B of low gray level and a B reference gamma voltage VL_B of high gray level to supply it to a B DAC  200 C. 
     Herein, the composition of each of the R reference gamma generator  68 R, the G reference gamma generator  68 G and the B reference gamma generator  68 B is the same as in  FIGS. 7A to 7C , thus their further detail description will be omitted. 
     A gamma generator  100  is integrated in the inside of the data integrated circuit  200  in the second embodiment, differently from the first embodiment. If the gamma generator  100  is integrated in the inside of the data integrated circuit  200  in this way, their mounting time is shortened when compared with the case that the data integrated circuit and the gamma generator are separated. 
       FIG. 10  is a diagram illustrating an EL display device according to a third embodiment of the present invention. 
     Referring to  FIG. 10 , an EL display device according to the embodiment of the present invention includes an EL display panel  160  having EL cells  170  arranged at each intersection of scan electrode lines SL and data electrode lines DL, a scan driver  162  to drive the scan electrode lines SL, a data driver  164  to drive the data electrode lines DL, and a gamma generation voltage supplier  172  to supply a gamma generation voltage to the data driver  164  so that a reference gamma voltage is generated. 
     Each of the EL cells  170  is selected when a scan pulse is applied to the scan electrode line SL, to generate the light corresponding to a data signal supplied to the data electrode line DL. In other words, when a designated light corresponding to the data signal is generated in each of the EL cells  170 , a designated picture is displayed in the EL display panel  160 . 
     The scan driver  162  sequentially supplies the scan pulse to a plurality of scan electrode lines SL. 
     The gamma generation voltage supplier  172  supplies a plurality of gamma generation voltages to the data driver  164  so that the reference gamma voltage is generated in the data driver  164 . Herein, the gamma generation voltage supplier  172  includes an R gamma generation voltage part  110 , a G gamma generation voltage part  112  and a B gamma generation voltage part  114  as in  FIG. 11  so that the reference gamma voltage is generated differently by R cell, G cell and B cell. Each of the gamma generation voltage part  110 ,  112 ,  114  is composed of divided voltage resistors to divide the voltage of a supply voltage source VDD. 
     The R gamma generation voltage part  110  includes two first divided voltage resistors r_R 1 _H, r_R 2 _H installed in series between the supply voltage source VDD and a ground voltage source GND to generate an R gamma generation voltage VHL_R of low gray level, and two second divided voltage resistors r_R 1 _L, r_R 2 _L installed in series between the supply voltage source VDD and the ground voltage source GND to generate an R gamma generation voltage VLL_R of high gray level. 
     Likewise, the G gamma generation voltage part  112  is composed of first divided voltage resistors r_G 1 _H, r_G 2 _H and second divided voltage resistors r_G 1 _L, r_G 2 _L to generate a G gamma generation voltage VHL_G of low gray level and a G gamma generation voltage VLL_G of high gray level. And, the B gamma generation voltage part  114  is composed of first divided voltage resistors r_B 1 _H, r_B 2 _H and second divided voltage resistors r_B 1 _L, r_B 2 _L to generate a B gamma generation voltage VHL_B of low gray level and a B gamma generation voltage VLL_B of high gray level. 
     The data driver  164  includes a reference gamma generator  1100  and a plurality of data integrated circuits  166 . The data integrated circuits  166  is composed as in  FIG. 4 , generates a data signal by dividing the reference gamma voltage supplied from the reference gamma generator  1100  into a plurality voltage levels, and supplies the generated data signal to the data electrode lines DL. 
     The reference gamma generator  1100  generates the reference gamma voltage in use of the gamma generation voltage supplied from the gamma generation voltage supplier  172 . For this, the reference gamma generator  1100  includes R reference gamma generators  168 R,  268 R, G reference gamma generators  168 G,  268 G, B reference gamma generators  168 B,  268 B. 
     A first embodiment of the reference gamma generator  1100  shown in  FIG. 10  is as follows. 
     The R reference gamma generator  168 R generates the R reference gamma voltage VH_R of low gray level and the R reference gamma voltage VL_R of high gray level in use of the R gamma generation voltage VHL_R of low gray level and the R gamma generation voltage VLL_R of high gray level. 
     The G reference gamma generator  168 G generates the G reference gamma voltage VH_G of low gray level and the G reference gamma voltage VL_G of high gray level in use of the G gamma generation voltage VHL_G of low gray level and the G gamma generation voltage VLL_G of high gray level. 
     The B reference gamma generator  168 B generates the B reference gamma voltage VH_B of low gray level and the B reference gamma voltage VL_B of high gray level in use of the B gamma generation voltage VHL_B of low gray level and the B gamma generation voltage VLL_B of high gray level. 
     The R reference gamma generation  168 R, the G reference gamma generation  168 G and the B reference gamma generation  168 B have different resistance value and control data value within the register, and have the same circuit composition. Putting focus on the R reference gamma generator  168 R, the operation of the reference gamma generators  168 R,  168 G and  168 B is described. 
     The R reference gamma generator  168 R includes a first DAC  184 , a second DAC  186  and a register  188  as in  FIG. 12 . 
     The first DAC  184  receives a first reference voltage VH from the external, and receives the R gamma generation voltage VHL_R of low gray voltage from the R gamma generation voltage part  110 . Herein, the first reference voltage is higher than the R gamma generation voltage VHL_R of low gray level. The first DAC  184  is composed of i (i is a natural number) bits, and divides the first reference voltage VH and the R gamma voltage into 2 i  numbers of voltage levels. And, the first DAC  184  supplies any one voltage among the voltages to the data integrated circuits  66 , as the R reference gamma voltage VH_R of low gray level, in correspondence to the bit of the first control data supplied from the register  188 . 
     The second DAC  186  receives a second reference voltage VL from the external, and receives the R gamma generation voltage VLL_R of high gray voltage from the R gamma generation voltage part  100 . Herein, the second reference voltage is a voltage between the first reference voltage VH and the R gamma generation voltage VLL_R of high gray level. The second DAC  186  is composed of j (j is a natural number) bits, and divides the second reference voltage VL and the R gamma voltage into 2 i  numbers of voltage levels. And, the second DAC  186  supplies any one voltage among the voltages to the data integrated circuits  166 , as the R reference gamma voltage VL_R of high gray level, in correspondence to the bit of the second control data supplied from the register  188 . 
     On the other hand, the second DAC  186  is composed to have more voltage levels than the first DAC  184  in this invention. In other words, the second DAC  186  outputs any one of the reference gamma voltage of 2 i  numbers of voltage levels when compared with that the first DAC  184  outputs any one among the reference gamma voltages of the 2 i  numbers of voltage levels, which is smaller than this. In this way, because the second DAC  186  selects the reference gamma voltage among the reference gamma voltages of the larger voltage levels, the present invention might control the R reference gamma voltage VL_R of high gray level more precisely than the prior art, thus the brightness deviation between the display panels  160  might be minimized. To describe this more precisely, the brightness of the display panel  160  might be expressed as in  FIG. 13 . In other words, black is displayed when the R reference gamma voltage VH_R of low gray level is supplied, and white is displayed when the R reference gamma voltage VL_R of high gray level is supplied. Herein, the brightness difference between low gray levels might not be easily distinctive with bare eyes, thus the gamma reference voltage is controlled by designated values so that it is relatively easy to similarly control the black brightness between the display panels  160 . On the contrary, the brightness difference between high gray levels is easily distinctive with bare eyes, thus the gamma reference voltage is divided into many voltage levels and one of them is selected, so that the white brightness between the display panels  160  might be set similarly. 
     According to an experiment result, in order to similarly set the brightness of low gray level between the display panels  160 , the gamma voltage is to be controlled at the range of approximate 3V. For example, when the first reference voltage VH: 14V, the R gamma generation voltage VHL_R: 11V are each set and when the voltage between the first reference voltage VH and the R gamma generation voltage VHL_R is subdivided to be about 0.2V, the brightness difference of the low gray level can be similarly set between the display panels  160 . Herein, when the first DAC  184  is set to be 4 bits, the 3V voltage is subdivided to have a voltage difference of about 0.1875V, thus the brightness of the low gray level might be similarly or identically set between the display panels  160 . 
     Further, the voltage value is to be controlled at the rage of about 5V in order that the brightness of the gray level is similarly set between the display panels  160 . For example, when the second reference voltage VL: 6V, the R gamma generation voltage VLL_R: 1V are each set and when the voltage between the second reference voltage VL and the R gamma generation voltage VLL_R is subdivided to be about 0.1 V, the brightness difference of the high gray level can be similarly set between the display panels  160 . Herein, when the second DAC  186  is set to be 6 bits, the 5V voltage is subdivided to have a voltage difference of about 0.078125V, thus the brightness of the high gray level might be similarly or identically set between the display panels  160 . 
     The first control data of i bit is stored at the register  188  to control the output value of the first DAC  184 . And the second control data of j bit is stored at the register  188  to control the output value of the second DAC  186 . Herein, the bit value of the first and second control data inputted into the register  188  is determined by a user. For example, the first and second control data, which can compensate the brightness deviation generated between the EL display panels  60 , is stored at the register  188 . When the brightness deviation is generated between the EL display panel  160 , the user controls the first and second control data values inputted to the register  188  thus the brightness deviation between the EL display panels  60  can be compensated. Further, a mode controller (not shown) is installed at the input terminal of the register  188 , and the register  188  receives the first and second control data from the mode controller to control the output of the first and second DAC  184 ,  186 , thus it is possible to control to display a picture of an appropriate brightness that corresponds to an external environment, i.e., day, night, rain, snow and etc. 
     The value stored at the register  188  included in the G reference gamma generator  168 G and the B reference gamma generator  168 B is set to make the white balance of the R cell, G cell and B cell balanced. 
     On the other hand, the gamma generation voltage supplier  172  of the present invention might be realized in many ways. For example, the gamma generation voltage supplier  172  might be composed as in  FIG. 14 . The R gamma generation voltage part  110 , the G gamma generation voltage part  112  and the B gamma generation voltage part  114  have substantially the same circuit composition except that the generated voltage value is different. 
     Referring to  FIG. 14 , the R gamma generation voltage part  190  includes first divided voltage resistors r_R 1 _H, r_R 2 _H, r_R 2 _H, and second divided voltage resistors r_R 1 _L, r_R 2 _L, r_R 2 _L installed in series between the supply voltage source VDD and the ground voltage source GND. Each of the first and second divided resistors includes three resistors. When comparing the R gamma generation voltage part  190  with the R gamma generation voltage part  110  of  FIG. 12 , the R gamma generation voltage part  110  shown in  FIG. 12  has three resistors in each of the first and second divided voltage resistors and generates the first reference voltage VH, the R gamma generation voltage VHL_R of low gray level, the second reference voltage VL and the R gamma generation voltage VLL_R of high gray level. 
     In other words, the R gamma generation voltage part  190  of  FIG. 14  additionally generates the first reference voltage VH to supply it to the first DAC  184  as well as additionally generating the second reference voltage VL to supply it to the second DAC  186 . In this way, when the first reference voltage and the second reference voltage VL are additionally generated in the R gamma generation voltage part  190 , there is an advantage that the brightness of the display panel  160  might be more easily controlled. 
     And, in the present invention, the data driver  164  as in  FIG. 15  includes one data integrated circuit  1200 . The reference gamma generator  1100  is integrated in the inside of the data integrated circuit  1200 . Herein, the R reference gamma generator  168 R generates the R gamma voltage VH_R of low gray level and the R gamma voltage VL_R of high gray level to supply them to an R DAC  1200 A. The G reference gamma generator  168 G generates the G gamma voltage VH_G of low gray level and the G gamma voltage VL_G of high gray level to supply them to an G DAC  1200 B. The B reference gamma generator  168 B generates the B gamma voltage VH_B of low gray level and the B gamma voltage VL_B of high gray level to supply them to an B DAC  1200 C. 
     The composition of each of the R reference gamma generator  168 R, the G reference gamma generator  168 G and the B reference gamma generator  168 B is substantially the same as the embodiment of  FIG. 12 . 
     In this way, when the gamma generator  1100  is integrated in the inside of the data integrated circuit  1200 , it is possible to obtain an additional effect that its mounting time is shortened. 
       FIG. 16  shows still another embodiment of a gamma generation voltage supplier  172 . 
     Referring to  FIG. 16 , the gamma generation voltage supplier  172  supplies a plurality of gamma generation voltages to the data driver  164  in order that the reference gamma voltage is generated in the data driver  164 . The gamma generation voltage supplier  172  includes the R gamma generation voltage part  2110 , the G gamma generation voltage part  2112  and the B gamma generation voltage part  2114  in order that a different reference gamma voltage is generated by R cell, G cell, B cell. Herein, each of the gamma generation voltage part  2110 ,  2112 ,  2114  is composed of a plurality of divided voltage resistors to divide the voltage of the supply voltage source VDD. 
     The R gamma generation voltage part  2110  supplies a first gamma generation voltage V 1  and a second gamma generation voltage V 2  to the data driver  164  for the R reference gamma voltage VH_R of low gray level to be generated, and in addition supplies a third gamma generation voltage V 3  and a fourth gamma generation voltage V 4  to the data driver  164  for the R reference gamma voltage VL_R of high gray level to be generated. Herein, the third gamma generation voltage V 3  and the fourth gamma generation voltage V 4  have a lower voltage value than the first gamma generation voltage V 1 . 
     The G gamma generation voltage part  2112  supplies a fifth gamma generation voltage V 5  and a sixth gamma generation voltage V 6  to the data driver  164  for the G reference gamma voltage VH_G of low gray level to be generated, and in addition supplies a seventh gamma generation voltage V 7  and a eighth gamma generation voltage V 8  to the data driver  164  for the G reference gamma voltage VL_G of high gray level to be generated. Herein, the seventh gamma generation voltage V 7  and the eighth gamma generation voltage V 8  have a lower voltage value than the fifth gamma generation voltage V 5 . 
     The B gamma generation voltage part  2114  supplies a ninth gamma generation voltage V 9  and a tenth gamma generation voltage V 10  to the data driver  164  for the B reference gamma voltage VH_B of low gray level to be generated, and in addition supplies a eleventh gamma generation voltage V 11  and a twelfth gamma generation voltage V 12  to the data driver  164  for the B reference gamma voltage VL_B of high gray level to be generated. Herein, the eleventh gamma generation voltage V 11  and the twelfth gamma generation voltage V 12  have a lower voltage value than the ninth gamma generation voltage V 9 . 
     A second embodiment of a reference gamma generator  1100  shown in  FIG. 10  is the same as in  FIGS. 17A to 17C . 
     The reference gamma generator  1100  includes an R reference gamma generator  268 R, a G reference gamma generator  268 G and a B reference gamma generator  268 B. 
     The R reference gamma generator  268 R generates the R reference gamma voltage VH_R of low gray level in use of the first gamma generation voltage V 1  and the second gamma generation voltage V 2 , and generates the R reference gamma voltage VL_R of high gray level in use of the third gamma generation voltage V 3  and the fourth gamma generation voltage V 4 . 
     The G reference gamma generator  268 G generates the G reference gamma voltage VH_G of low gray level in use of the fifth gamma generation voltage V 5  and the sixth gamma generation voltage V 6 , and generates the G reference gamma voltage VL_G of high gray level in use of the seventh gamma generation voltage V 7  and the eight gamma generation voltage V 8 . 
     The B reference gamma generator  268 B generates the B reference gamma voltage VH_B of low gray level in use of the ninth gamma generation voltage V 9  and the tenth gamma generation voltage V 10 , and generates the B reference gamma voltage VL_B of high gray level in use of the eleventh gamma generation voltage V 11  and the twelfth gamma generation voltage V 12 . 
     The R reference gamma generator  268 R, the G reference gamma generator  268 G and the B reference gamma generator  268 B substantially the same circuit composition, thus putting focus on the R reference gamma generator  268 R, the operation of the reference gamma generators  268 R,  268 G and  268 B is described. 
     The R reference gamma generator  268 R includes a first DAC  284 R, a second DAC  286 R and a register  288 R as in  FIG. 17A . The first DAC  284 R divides the first gamma generation voltage V 1  and the second gamma generation voltage V 2  supplied from the gamma generation voltage supplier  172 , into a plurality of voltage levels. 
     The first DAC  284 R divides the first gamma generation voltage V 1  and the second gamma generation voltage V 2  into 2 i  (i is a natural number) numbers of voltage levels. And, the first DAC  284 R supplies any one voltage among the 2 i  numbers of voltages to the data integrated circuits  166 , as the R reference gamma voltage VH_R of low gray level, in correspondence to the first control data of i bit supplied from the register  288 . 
     The second DAC  286 R divides the third gamma generation voltage V 3  and the fourth gamma generation voltage V 4  supplied from the gamma generation voltage supplier  272 , into 2 j  (j&gt;i, j is a natural number) of voltage levels. And the second DAC  268 R supplies any one voltage among the 2 j  numbers of voltages to the data integrated circuits  166 , as the R reference gamma voltage VL_R of high gray level, in correspondence to the first control data of j bit supplied from the register  288 . 
     Likewise, the second DAC  286 R divides the gamma reference voltage into the voltage levels that are more than those of the first DAC  284 R. In other words, the second DAC  286 R has the 2 j  numbers of voltage levels and the first DAC  284 R has the 2 i  numbers of voltage levels which is smaller than that. In this way, if the second DAC  286 R has more voltage levels, the R reference gamma voltage VL_R of high gray level can be controlled precisely, thus the brightness deviation between the display panels  60  can be precisely controlled in the high gray level where the gray level difference is easily perceived with bare eyes. 
     The first control data of i bit is stored at the register  288 R to control the output of the first DAC  284 R. And the second control data of j bit is stored at the register  288 R to control the output of the second DAC  286 R. Herein, the bit value of the first and second control data inputted to the register  288 R is determined by a user. For example, the first and second control data, which can compensate the brightness deviation generated between the EL display panels  160 , is stored at the register  288 R. 
     The G reference gamma generator  268 G of  FIG. 7B  generates the G reference gamma voltage VH_G of low gray level and the G reference gamma voltage VL_G of high gray level in use of the fifth to eighth gamma generation voltage (V 5  to V 8 ). And, the B reference gamma generator  268 B as in  FIG. 7C  generates the B reference gamma voltage VH_B of low gray level and the B reference gamma voltage VL_B of high gray level in use of the ninth to twelfth gamma generation voltage V 9  to V 12 . 
     This invention might control the reference gamma voltage precisely in use of the control data stored at the registers  288 R,  288 G,  288 B, thus the brightness of the display panel  60  might be controlled minutely. Accordingly, this invention can deal with the brightness deviation between the display panels actively, thus its process time might be shortened. 
     On the other hand, if the bit number of the control data stored at the second DAC&#39;s  286 R,  286 G,  286 B is big, there is a problem that the size of the second DAC&#39;s  286 R,  286 G,  286 B is big. For example, the second DAC&#39;s  286 R,  286 G,  286 B includes 64 numbers of resistors R 1  to R 64  as in  FIG. 18  to generate sixty four different voltages, as well as includes a selector  71  to output any one voltage among the sixty four voltage levels in correspondence to the second control data. 
     If each of the second DAC&#39;s  286 R,  286 G,  286 B includes the sixty four resistors R 1  to R 64  and the selector  71  which is to output any one voltage among the sixty four voltages, the size of the second DAC  286 R,  286 G,  286 B becomes bigger, thus its circuit cost gets bigger as much and it becomes difficult to secure the degree of freedom for design. Especially, such problems are to be shown in a bigger scale when the second DAC&#39;s  286 R,  286 G,  286 B are integrated in the inside of the data integrated circuit  266 . 
     In order to overcome such problems, the reference gamma generator  1100  includes the R reference gamma generator  268 R, the G reference gamma generator  268 G and the B reference gamma generator  268 B, which are composed as in  FIGS. 19A to 19C . The R reference gamma generator  268 R, the G reference gamma generator  268 G and the B reference gamma generator  268 B substantially have the same circuit composition, thus putting focus on the R reference gamma generator  268 R, the operation of the reference gamma generators  268 R,  268 G and  268 B is described. 
     The R reference gamma generator  268 R includes a first DAC  290 R, a second DAC  292 R and a register  294 R as in  FIG. 19A . 
     The first DAC  290 R divides the first gamma generation voltage V 1  and the second gamma generation voltage V 2  supplied from the gamma generation voltage supplier  172 , into a plurality of voltage levels. For example, the first DAC  290 R divides the first gamma generation voltage V 1  and the second gamma generation voltage V 2  into 2 i  numbers of voltage levels. And the first DAC  290 R supplies any one voltage among a number of voltages to the data integrated circuits  166 , as the R reference gamma voltage VH_R of low gray level, in correspondence to the bit of the first control data supplied from the register  296 R. 
     The second DAC  292 R divides the third gamma generation voltage V 3  and the fourth gamma generation voltage V 4  supplied from the gamma generation voltage supplier  172 , into a plurality of voltage levels. For example, the second DAC  292 R divides the third gamma generation voltage V 3  and the fourth gamma generation voltage V 4  into 2 j /2 numbers of voltage levels so that it can be selected by the control data of j/2 (j&gt;i, j/2&lt;i: e.g., j/2 is set to be ‘3’). And the second DAC  292 R supplies the adjacent first divided voltage VL 1  and second divided voltage VL 2  among a plurality of voltages to the third DAC  294 R, in correspondence to the bit of the second control data supplied from the register  296 R. For example, the second DAC  292 R divides the third gamma generation voltage V 3  and the fourth gamma generation voltage V 4  into voltages of eight steps as in  FIG. 20 , and the adjacent voltages among the divided voltages, as the first divided voltage VL 1  and the second divided voltage VL 2 , are supplied to the third DAC  294 R, in correspondence to the second control data. And then, the third DAC  294 R divides the first divided voltage VL 1  and the second divided voltage VL 2  supplied from the second DAC  292 R to 2 j /2 numbers of voltage level (8 voltage levels). And, the third DAC  294 R supplies any one voltage among the voltages, as the R reference gamma voltage VL_R of high gray level, to the data integrated circuits, in correspondence to the bit of the third control data. 
     In this way, the present invention has its size reduced by more than ½ and secures more degree of freedom for design, when compared with the embodiment of  FIGS. 17A to 17C , in use of the second and third DAC  92 ,  94  where the output voltage can be selected by the j/2 bit. For example, assuming that j is 6 bit, each of the second DAC  292 R and the third DAC  294 R includes eight resistors. Accordingly, the number of resistors thereof is reduced greatly than that of the sixty four resistors included in the second DAC  286 R shown in  FIG. 17A , and accordingly the size gets smaller. 
     The first control data of i bit is stored in the register  296 R to control the output value of the first DAC  290 R. And the second and third control data of j/2 bit are stored at the register  296 R to control the output of the second DAC  292 R and the third DAC  294 R. Herein, the bit value of the first to third control data having been inputted in the register  296 R is set to compensate the brightness deviation generated between the EL display panel  160 . 
     The G reference gamma generator  268 G of  FIG. 19B  generates the G reference gamma voltage VH_G of low gray level and the G reference gamma voltage VL_G of high gray level in use of the fifth to eighth gamma generation voltage V 5  to V 8 . And, the B reference gamma generator  268 B of  FIG. 19C  generates the B reference gamma voltage VH_B of low gray level and the B reference gamma voltage VL_B of high gray level in use of the ninth to twelfth gamma generation voltage V 9  to V 12 . 
     The reference gamma generator  1100  included in the reference gamma generators  268 R,  268 G,  268 B might be integrated in the inside of the data integrated circuit  1200  as in  FIG. 15 . Further, the gamma generation voltage supplier  172  along with the reference gamma generator  1100  might be integrated in the inside of the data integrated circuit  1200  as in  FIG. 21 . In  FIG. 21 , the reference numerals “ 1200 A”, “ 1200 B”, “ 1200 B” represent the R DAC, the G DAC and the B DAC, respectively. 
       FIG. 22  represents an EL display device according to still another embodiment of the present invention. 
     Referring to  FIG. 22 , the EL display device according to the embodiment of the present invention includes an EL display panel  360  having EL cells  370  arranged at each intersection of scan electrode lines SL and data electrode lines DL, a scan driver  362  to drive the scan electrode lines SL, a data driver  364  to drive the data electrode lines DL, and a gamma generation voltage supplier  372  to generate gamma generation voltages. 
     The gamma generation voltage supplier  372  generates the reference gamma voltages VH_R, VH_G, VH_B of low gray level to supply them to the data integrated circuits  366 . And, the gamma generation voltage supplier  372  supplies a plurality of gamma generation voltages to a reference gamma generator  3100  included in the data driver  364  so that the reference gamma voltages VL_R, VL_G, VL_B of high gray level are generated. The gamma generation voltage supplier  372  includes an R gamma generation voltage part  3110 , a G gamma generation voltage part  3112 , a B gamma generation voltage part  3114  as in  FIG. 23 , so that different reference gamma voltages VH_R, VH_G, VH_B and the gamma generation voltage can be generated by R cell, G cell, B cell. 
     The R gamma generation voltage part  3110  includes a first variable resistor VR 1  to generate the reference gamma voltage VH_R of low gray level, and divided voltage resistors r_R 1 , r_R 2 , r_R 3  to generate the first and second gamma generation voltages V 1  and V 2  by dividing the reference gamma voltage VH_R of low gray level. Herein, the reference gamma voltage VH_R of low gray level is supplied to the data integrated circuit  366  and the first and second gamma generation voltage V 1 , V 2  are supplied to the reference gamma generator  3100 . 
     The G gamma generation voltage part  3112  includes a second variable resistor VR 2  to generate the reference gamma voltage VH_G of low gray level, and divided voltage resistors r_G 1 , r_, r_G 3  to generate the third and fourth gamma generation voltages V 3  and V 4  by dividing the reference gamma voltage VH_G of low gray level. Herein, the reference gamma voltage VH_G of low gray level is supplied to the data integrated circuit  366  and the third and fourth gamma generation voltage V 3 , V 4  are supplied to the reference gamma generator  3100 . 
     The B gamma generation voltage part  3114  includes a third variable resistor VR 3  to generate the reference gamma voltage VH_B of low gray level, and divided voltage resistors r_B 1 , r_B 2 , r_B 3  to generate the fifth and sixth gamma generation voltages V 5  and V 6  by dividing the reference gamma voltage VH_B of low gray level. Herein, the reference gamma voltage VH_B of low gray level is supplied to the data integrated circuit  366  and the fifth and sixth gamma generation voltage V 5 , V 6  are supplied to the reference gamma generator  3100 . 
     The data driver  364  includes the reference gamma generator  3100  and at least one data integrated circuit  366 . The data integrated circuit  366  is composed as in  FIG. 4 , and divides the reference gamma voltages supplied from the gamma generation voltage supplier  372  and the reference gamma generator  3100  into a plurality of voltage levels to generate a data signal, thereby supplying the data signal to the data electrode lines DL. 
     The reference gamma generator  3100  generates the reference gamma voltages of high gray level in use of the gamma generation voltages supplied from the gamma generation voltage supplier  372 . For this, the reference gamma generator  3100  includes the R reference gamma generator  368 R, the G reference gamma generator  368 G, the B reference gamma generator  368 B. 
     The R reference gamma generator  368 R generates the reference gamma voltage VL_R of high gray level in use of the first gamma generation voltage V 1  and the second gamma generation voltage V 2 . The G reference gamma generator  368 G generates the reference gamma voltage VL_G of high gray level in use of the third gamma generation voltage V 3  and the fourth gamma generation voltage V 4 . The B reference gamma generator  368 B generates the reference gamma voltage VL_B of high gray level in use of the fifth gamma generation voltage V 5  and the sixth gamma generation voltage V 6 . Herein, the R reference gamma generator  368 R, the G reference gamma generator  368 G and the B reference gamma generator  368 B substantially have the same circuit composition, thus putting focus on the R reference gamma generator  368 R, the operation of the reference gamma generators  368 R,  368 G and  368 B is described. 
     The R reference gamma generator  368 R includes a DAC  386 R and a register  388 R as in  FIG. 24A . The DAC  386 R divides the first gamma generation voltage V 1  and the second gamma generation voltage V 2  supplied from the gamma generation voltage supplier  372  into a plurality of voltage levels. For example, the DAC  386 R is composed of i bit (i is a natural number), and divides the first gamma generation voltage V 1  and the second gamma generation voltage V 2  into 2 i  numbers of voltage levels. And the DAC  386 R supplies any one voltage among the 2 i  numbers of voltage levels, as the reference gamma voltage VL_R of high gray level, to the data integrated circuits  366 , in correspondence to the control data supplied from the register  388 R. 
     In this embodiment, the reference gamma voltage VH controls the voltage value in use of the variable resistors VR 1 , VR 2  and VR 3 , and controls the voltage value in use of the reference gamma voltage VL of high gray level. If the reference gamma voltage VL of high gray level in this way is precisely adjusted by the DAC  386 R, then the brightness deviation between the display panels  360  is minimized. 
     The control data of i bit is stored at the register  388 R to control the output value of the DAC  386 R. Herein, the bit value of the control data inputted into the register  388 R is determined by a user. For example, the register  388 R might store the control data where a bit value is set to compensate the brightness deviation generated between the display panels  360 . When there is a brightness deviation between the EL display panels  60 , the user controls the brightness of low gray level in use of the variable resistance value of the first to third variable resistors VR 1  to VR 3 , and controls the bit value of the control data, thereby enabling to compensate the brightness deviation between the display panels  360 . Further, the input terminal of the register  388 R has a mode controller (not shown) installed, and the register  388 R controls the output value of the DAC  386 R by receiving the control data from the mode controller, thus it is possible to control to display a picture of an appropriate brightness that corresponds to an external environment, i.e., day, night, rain, snow and etc. 
     In this invention, the G reference gamma generator  368 G and the B reference gamma generator  368 B are composed as in  FIGS. 24B and 24C . The G reference gamma generator  368 G generates the reference gamma voltage VL_G of high gray level in use of the third and fourth gamma generation voltage V 3 , V 4 . And the B reference gamma generator  368 B generates the reference gamma voltage VL_B of high gray level in use of the fifth and sixth gamma generation voltage V 5 , V 6 . In  FIGS. 24B and 24C , the reference numerals “ 386 G” and “ 386 B” represent the DAC, and “ 388 G” and “ 388 B” represent the register. 
     In this invention, the circuits of the reference gamma generator might be integrated in the inside of the data integrated circuit  366  as in  FIG. 25 . In  FIG. 25 , the reference numerals “ 3200 A”, “ 3200 B” and “ 3200 C” represent the DAC. 
     As described above, according to the electro-luminescence display device of the present invention, the reference gamma voltage can be adjusted in use of the control data stored at the register, thus the expression capability of gray level is improved, the brightness deviation between the display panels might be compensated in a short time, and the gamma adjustment time and the process time might be reduced. In addition, the present invention might compensate the brightness deviation exactly because the reference gamma voltage is selected as any one of voltage levels. Further, the gamma voltage generator in this invention is mounted on the COF, thus FPC might be removed, and the number of resistors mounted on the FPC is reduced to decrease the area of the FPC, thereby enabling to secure its design margin broadly. In addition, the invention has the align time of the COF and FPC shortened so that it is possible to obtain an additional effect that its process time might be reduced. 
     Although the present invention has been explained by the embodiments shown in the drawings described above, it should be understood to the ordinary skilled person in the art that the invention is not limited to the embodiments, but rather that various changes or modifications thereof are possible without departing from the spirit of the invention. Accordingly, the scope of the invention shall be determined only by the appended claims and their equivalents.