Patent Publication Number: US-10762851-B2

Title: Timing controller and display device including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to and the benefit of Korean Patent Application No. 10-2017-0122549 filed in the Korean Intellectual Property Office on Sep. 22, 2017, the entire content of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     Aspects of some example embodiments of the present invention relate to a timing controller and a display device including the same. 
     2. Description of the Related Art 
     A display device may be embodied as an organic light emitting diode display including pixels formed by organic light emitting diodes. In general, an organic light emitting diode outputting green light has a higher luminous efficiency than an organic light emitting diode outputting red light or blue light, so that a sufficient luminance can be obtained even at a small current. Therefore, a driving current of the organic light emitting diode outputting green light may be smaller than that of the organic light emitting diode outputting red light or blue light, and a parasitic capacitance of the organic light emitting diode outputting green light and connected in parallel structurally may be larger than that of the organic light emitting diode outputting red light or blue light. 
     In the case where the organic light emitting diode display displays black and then displays white, although a current flowing through the organic light emitting diode outputting green light is smaller than a current flowing through the organic light emitting diode outputting red light or blue light, a charge amount for causing a voltage difference at both ends of the organic light emitting diode outputting green light to be equal to or higher than a threshold voltage is larger than a charge amount at both ends of the organic light emitting diode outputting red light or blue light. Therefore, the organic light emitting diode outputting green light may have a larger emission delay than the organic light emitting diode outputting red light or blue light, so that a color drag phenomenon in which the white displayed by the display device appears to have a purple color may occur. 
     Meanwhile, a driving transistor included in a pixel has a hysteresis characteristic in which a threshold voltage and a current of the driving transistor change based on a change of a gate voltage. Due to the hysteresis characteristic of the driving transistor, a current different from the current set in the pixel flows according to the previous luminance of the pixel. Therefore, the luminance of the pixel may not reach a target luminance (or a target grayscale level). 
     For example, display defects such as the emission delay of the pixel including the organic light emitting diode outputting green light and the color drag and an afterimage due to the hysteresis of the driving transistor may be easily observed by a user at low-luminance emission of the display device and cause inconvenience in viewing the display device. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background and therefore it may contain information that does not constitute prior art. 
     SUMMARY 
     Aspects of some example embodiments of the present invention relate to a timing controller and a display device including the same. Some example embodiments relate to a timing controller and a display device including the same for improving display quality. 
     Some example embodiments may be related to a display device that controls an interval between gate-on periods of a scan start signal based on a dimming level. 
     Some example embodiments may be related to a display device that controls a width of a gate-on period of a scan start signal based on a dimming level. 
     Some example embodiments may be related to a timing controller included in the display device. 
     It should be understood, however, that aspects of the present invention are not limited to the aspects described above, and various changes and modifications may be made without departing from the spirit and scope of the invention. 
     According to some example embodiments of the present invention, a display device includes: a display panel including a plurality of pixels; a scan driver configured to supply a scan signal to the plurality of pixels through a plurality of scan lines based on a scan start signal; an emission driver configured to supply an emission control signal to the plurality of pixels through a plurality of emission control lines based on an emission control start signal; and a timing controller configure to control an interval between a plurality of gate-on periods of the scan start signal within a gate-off period of the emission control start signal based on a dimming level. 
     According to some embodiments, the gate-on periods include a first gate-on period and a second gate-on period, and the interval between the first gate-on period and the second gate-on period is a first interval when the dimming level corresponds to a predetermined reference dimming level. 
     According to some embodiments, the interval between the first gate-on period and the second gate-on period is a second interval larger than the first interval when the dimming level is lower than the reference dimming level. 
     According to some embodiments, the interval between the first gate-on period and the second gate-on period increases as the dimming level decreases in a first dimming period of which the dimming level is lower than the reference level. 
     According to some embodiments, the first gate-on period and the second gate-on period are continuous with each other in a second dimming period of which the dimming level is higher than the reference level. 
     According to some embodiments, the interval between the first gate-on period and the second gate-on period is a second interval smaller than the first interval in a second dimming period of which the dimming level is higher than the reference level. 
     According to some embodiments, a width of the first gate-on period and a width of the second gate-on period are constant regardless of the dimming level. 
     According to some embodiments, a width of at least one of the first gate-on period or the second gate-on period increases based on a predetermined dimming level as the dimming level decreases. 
     According to some embodiments, the gate-on periods include a first gate-on period and a second gate-on period, the scan driver is configured to supply j (j is a positive integer) scan signals to each of the scan lines in response to the first gate-on period of the scan start signal, and the scan driver is configured to supply k (k is an integer of 2 or more) scan signals to each of the scan lines in response to the second gate-on period of the scan start signal. 
     According to some embodiments, a number of scan signals supplied to each of the scan lines increases as a width of the second gate-on period increases. 
     According to some embodiments, the timing controller is configured to control a width of the gate-off period of the emission control start signal supplied to the emission driver based on the dimming level. 
     According to some embodiments, a width of the gate-off period of the emission control start signal is a first off-width when the dimming level corresponds to a predetermined reference dimming level, the width of the gate-off period of the emission control start signal increases as the dimming level decreases when the dimming level is lower than the reference dimming level, and the width of the gate-off period of the emission control start signal is a second off-width smaller than the first off-width regardless of the dimming level when the dimming level is higher than the reference dimming level. 
     According to some embodiments, the timing controller includes: a first start signal determiner configured to determine a width of the gate-off period of the emission control start signal based on a dimming signal including information of the dimming level; and a second start signal determiner configured to determine the interval between a first gate-on period and a second gate-on period of the scan start signal based on at least one of the dimming signal and the width of the gate-off period of the emission control start signal. 
     According to some embodiments, the display device further includes a data driver configured to supply a data signal to a plurality of data lines so as to be synchronized with a last scan signal of each of the plurality of scan lines among the scan signals supplied to each of the plurality of scan lines. 
     According to some embodiments, the scan driver is configured to supply a scan signal to each of the plurality of scan lines a plurality of times in response to the gate-on periods of the scan start signal within a non-emission period defined by a gate-off period of the emission control signal in one frame period. 
     According to some embodiments, the scan driver is configured to control an interval between the scan signal output in response to a first gate-on period and the scan signal output in response to a second gate-on period according to an interval between the first gate-on period and the second gate-on period of the scan start signal. 
     According to some example embodiments of the present invention, a display device includes: a display panel including a plurality of pixels; a scan driver configured to supply a scan signal to the plurality of pixels through a plurality of scan lines based on a scan start signal; an emission driver configured to supply an emission control signal to the plurality of pixels through a plurality of emission control lines based on an emission control start signal; and a timing controller configured to control a width of the scan start signal in a gate-off period of the emission control start signal defining a non-emission period of one frame based on a dimming level. 
     According to some embodiments, the scan start signal has a first width when the dimming level corresponds to a predetermined reference dimming level. 
     According to some embodiments, the scan start signal has a second width larger than the first width when the dimming level is lower than the reference dimming level. 
     According to some embodiments, a width of the scan start signal increases as the dimming level decreases when the dimming level is included in a first dimming period lower than the reference dimming level. 
     According to some embodiments, the scan start signal has a second width smaller than the first width when the dimming level is included in a second dimming period higher than the reference dimming level. 
     According to some embodiments, the scan start signal has a constant second width regardless of a change in the dimming level in the second dimming period. 
     According to some embodiments, the scan driver is configured to supply k (k is an integer of 2 or more) scan signals to each of the scan lines based on the width of the scan start signal. 
     According to some embodiments, the timing controller includes: a first start signal determiner configured to control a width of the gate-off period of the emission control start signal based on a dimming signal including information of the dimming level; and a second start signal determiner configured to control the width a the gate-on period of the scan start signal based on the dimming signal and the width of the gate-off period of the emission control start signal. 
     According to some example embodiments of the present invention, a timing controller includes: a first start signal determiner configured to determine a width of a gate-off period of an emission control start signal based on a dimming signal including information of a dimming level at which a display device emits light; and a second start signal determiner configured to determine at least one interval between a gate-on period of a scan start signal and at least one width of a gate-on period of the scan start signal based on the dimming signal. 
     According to some embodiments, the gate-on period includes a first gate-on period and a second gate-on period, and when the dimming level corresponds to a predetermined reference dimming level, the interval between the first gate-on period and the second gate-on period is a first interval. 
     According to some embodiments, the interval between the first gate-on period and the second gate-on period increases as the dimming level decreases in a first dimming period of which the dimming level is lower than the reference level. 
     According to some embodiments, the first gate-on period and the second gate-on period are continuous with each other in a second dimming period of which the dimming level is higher than the reference level. 
     According to some embodiments, the scan start signal has a first width when the dimming level corresponds to a predetermined reference dimming level. 
     According to some embodiments, a width of the scan start signal increases as the dimming level decreases when the dimming level is included in a first dimming period lower than the reference dimming level. 
     According to some embodiments, the scan start signal has a constant second width smaller than the first width regardless of a change in the dimming level when the dimming level is included in a second dimming period higher than the reference dimming level. 
     Therefore, display defects such as a color drag and afterimage due to an abrupt gradation change in low-luminance may be eliminated or reduced. 
     It should be understood, however, that the characteristics of the present invention are not limited to the characteristics described above, and various changes and modifications may be made without departing from the spirit and scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing a display device according to some example embodiments of the present invention. 
         FIG. 2A  is a circuit diagram showing an example of a pixel included in the display device of  FIG. 1 . 
         FIG. 2B  is a waveform diagram showing an example of driving the pixel of  FIG. 2A . 
         FIG. 3  is a block diagram showing an example of a scan driver included in the display device of  FIG. 1 . 
         FIGS. 4A and 4B  are waveform diagrams showing examples of an operation of the scan driver of  FIG. 3 . 
         FIG. 5  is a waveform diagram showing an example of scan signals supplied to a display panel of the display device of  FIG. 1 . 
         FIGS. 6A to 6D  are waveform diagrams showing examples of an operation of the display device of  FIG. 1  based on a dimming level according to some example embodiments of the present invention. 
         FIG. 7  is a block diagram showing an example of an emission driver included in the display device of  FIG. 1 . 
         FIGS. 8A and 8B  are waveform diagrams showing examples of an operation of the emission driver of  FIG. 7 . 
         FIGS. 9A to 9C  are block diagrams showing examples of a timing controller included in the display device of  FIG. 1 . 
         FIGS. 10A to 10C  are waveform diagrams showing examples of an operation of the display device of  FIG. 1  based on a dimming level according to some example embodiments of the present invention. 
         FIGS. 11A to 11C  are waveform diagrams showing examples of an operation of the display device of  FIG. 1  based on a dimming level according to some example embodiments of the present invention. 
         FIGS. 12A and 12B  are waveform diagrams showing another example of an operation of the display device of  FIG. 1  based on a dimming level. 
         FIG. 13  is a block diagram showing a display device according to some example embodiments of the present invention. 
         FIG. 14  is a block diagram showing a display device according to some example embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, example embodiments of the present invention will be described in further detail with reference to the accompanying drawings. Like reference numerals are used for like elements in the drawings, and redundant explanations for like elements are omitted. 
       FIG. 1  is a block diagram showing a display device according to some example embodiments of the present invention. 
     Referring to  FIG. 1 , the display device  1000  may include a display panel  100 , a scan driver  200 , an emission driver  300 , a data driver  400 , and a timing controller  500 . 
     The display device  1000  may be implemented as an organic light emitting diode display, a liquid crystal display, or the like. The display device  1000  may be a flat display device, a flexible display device, a curved display device, a foldable display device, or a bendable display device. In addition, the display device  1000  may be applied to a transparent display device, a head-mounted display device, a wearable display device, and the like. 
     The display panel  100  may include a plurality of scan lines SL 1  to SLn, a plurality of emission control lines EL 1  to ELn, and a plurality of data lines DL 1  to DLm, and may include a plurality of pixels P connected to each of the scan lines SL 1  to SLn, the emission control lines EL 1  to ELn, and the data lines DL 1  to DLm (wherein n and m are integers larger than 1). Each of the pixels P may include a driving transistor and a plurality of switching transistors. In an example embodiment, the pixels P may include organic light emitting diode display and each of the pixels P may be implemented as one of red, green, and blue pixels. 
     The scan driver  200  may supply the scan signals to the pixels P through the scan lines SL 1  to SLn based on the scan start signal SFLM. The scan driver  200  receives the scan start signal SFLM and at least one clock signal from the timing controller  500 . In an example embodiment, when the scan signal is supplied to the first scan line SL 1 , the pixels P may be sequentially selected by a horizontal line. For this purpose, the scan signal may be set to a gate-on voltage so that transistors included in the pixels P may be turned on. For example, when the transistor included in the pixels P is a P-channel metal oxide semiconductor (PMOS) transistor, the gate-on voltage may be set to a logic high level. 
     In an example embodiment, and the number of scan signals output may be different according to a width of the gate-on period of the scan start signal SFLM and the clock signal. This will be described later in more detail referring to  FIG. 3  and the following drawings. 
     The emission driver  300  may supply the emission control signals to the pixels P through the emission control lines EL 1  to ELn based on an emission control start signal EFLM. The emission driver  300  receives the emission control start signal EFLM and a clock signal from the timing controller  500 . In an example embodiment, when the emission control signal is supplied to the first emission control line EL 1 , the pixels P may be sequentially selected by a horizontal line. For this purpose, the emission control signal may be set to a gate-on voltage so that the transistors included in the pixels P may be turned on. The emission control signal may divide one frame into an emission period and a non-emission period with respect to the horizontal lines. 
     The data driver  400  may receive a data control signal DCS and a video data signal RGB from the timing controller  500 . The data driver  400  may supply the data signals to the pixels through the data lines DL 1  to DLm based on the data control signal DCS and the video data signal RGB. In an example embodiment, in one frame, the data driver  400  may supply the data signals to the data lines DL 1  to DLm to be synchronized with the last scan signal of each of the scan lines SL 1  to SLn among the scan signals supplied to each of the scan lines SL 1  to SLn. 
     The timing controller  500  may control driving of the scan driver  200 , the emission driver  300 , and the data driver  400  based on timing signals supplied from the outside. The timing controller  500  may supply a control signal including a scan start signal SFLM, a scan clock signal, and the like to the scan driver  200 , and may supply a control signal including the emission control start signal EFLM, the emission control clock signal, and the like to the emission driver  300 . The data control signal DCS for controlling the data driver  500  may include a source start signal, a source output enable signal, a source sampling clock signal, and the like. 
     In an example embodiment, the timing controller  500  may determine a dimming level at which the display panel  100  is currently emitting light based on a dimming signal supplied from the outside. Herein, dimming refers to a technique for limiting the maximum luminance (e.g., the luminance of the maximum gradation) that the display panel  100  may display. For example, the dimming refers to displaying an image by selecting one of a plurality of predetermined dimming levels, and the luminance of the maximum gradation may be changed to 350 nit, 250 nit, 200 nit, or the like according to the dimming level. For example, as the dimming level increases, the maximum luminance that the display panel can display increases. 
     In some example embodiments, the dimming may be implemented by various methods known at present, such as a data signal conversion, a gamma set selection, and a control of an off-duty ratio of the emission control signal. In addition, the dimming may be implemented in different ways according to a luminance period. 
     The timing controller  500  may determine a length (or a width) of the gate-off period of the emission control start signal EFLM based on the dimming level. In other words, the timing controller  500  may determine the length (e.g., an off-duty ratio) of the non-emission period in one frame based on the dimming level. 
     For example, at the predetermined reference dimming level, the gate-off period of the emission control start signal EFLM may have a first width. In the first dimming period in which the dimming level is lower than the reference dimming level, the gate-off period of the emission control start signal EFLM may have a second width larger than the first width. For example, the second width may increase as the dimming level decrease. In the second dimming period in which the dimming level is higher than the reference dimming level, the gate-off period of the emission control start signal EFLM may have a third width smaller than the first width. For example, the third width may have a constant value regardless of a change of the dimming level. 
     In an example embodiment, the timing controller  500  may control an interval between a first gate-on period and a second gate-on period of the scan start signal SFLM based on the dimming level in the gate-off period of the emission control start signal EFLM. A holding time of a threshold voltage bias of the driving transistor in the pixel P may be controlled according to the interval between the first gate-on period and the second gate-on period. 
     In an example embodiment, the timing controller  500  may control the width of the scan start signal SFLM (e.g., the width of the gate-on period of the scan start signal SFLM) based on the dimming level in the gate-off period of the emission control start signal EFLM. The number of scan signals supplied to the scan lines SL 1  to SLn may change according to the width of the scan start signal SFLM. Therefore, an initialization of the on-bias state of the driving transistor in the pixel P may be applied differently according to the dimming level (e.g., the maximum luminance of the display panel  100 ). 
     A description related to a driving according to the dimming level will be described in more detail with reference to  FIG. 2  and the following drawings. 
       FIG. 2A  is a circuit diagram showing an example of a pixel included in the display device of  FIG. 1  and  FIG. 2B  is a waveform diagram showing an example of driving the pixel of  FIG. 2A . 
       FIGS. 2A and 2B  show a pixel P connected to the i-th data line Di, the (i- 1 ) th scan line SLi- 1  and the i-th scan line SLi for convenience of description. 
     Referring to  FIGS. 2A and 2B , the pixel P may include the organic light emitting diode OLED and a pixel circuit  10  for controlling an amount of current supplied to the organic light emitting diode OLED. 
     The anode electrode of the organic light emitting diode OLED may be connected to the pixel circuit  10  and the cathode electrode of the organic light emitting diode OLED may be connected to the second power source ELVSS. The organic light emitting diode OLED may generate light of a predetermined luminance corresponding to the amount of current supplied from the pixel circuit  10 . 
     The pixel circuit  10  may control the amount of current flowing from the first power source ELVDD via the organic light emitting diode OLED to the second power source ELVSS in response to the data signal. For this purpose, the pixel circuit  10  may include first to seventh transistors T 1  to T 7  and a storage capacitor Cst. 
     The seventh transistor T 7  is connected between an initialization power supply VINT and the anode electrode of the organic light emitting diode OLED. A gate electrode of the seventh transistor T 7  is connected to the ith scan line SLi. The seventh transistor T 7  is turned on when a scan signal (e.g., GW signal) is supplied to the i-th scan line SLi to supply a voltage of the initialization power supply VINT to the anode electrode of the organic light emitting diode OLED. Herein, the initialization power supply VINT may be set to a voltage lower than the data signal. 
     The sixth transistor T 6  is connected between the first transistor T 1  and the organic light emitting diode OLED. A gate electrode of the sixth transistor T 6  is connected to the i-th emission control line Eli. The sixth transistor T 6  is turned on when the emission control signal EMi is supplied to the i-th emission control line ELi, and is turned off in the other cases. For example, the sixth transistor T 6  may be turned on in the gate-on period of the emission control signal supplied to the i-th emission control line ELi, and may be turned off in the gate-off period. 
     The fifth transistor T 5  is connected between the first power source ELVDD and the first transistor T 1 . A gate electrode of the fifth transistor T 5  is connected to the i-th emission control line Eli. The fifth transistor T 5  is turned off when the emission control signal EMi is supplied to the i-th emission control line ELi, and is turned on in other cases. 
     The first electrode of the first transistor T 1  (e.g., a driving transistor) is connected to the first power source ELVDD via the fifth transistor T 5 , and the second electrode of the first transistor T 1  is connected to the anode electrode of the organic light emitting diode OLED via the sixth transistor T 6 . A gate electrode of the first transistor T 1  is connected to the first node N 1 . The first transistor T 1  controls an amount of current flowing from the first power source ELVDD via the organic light emitting diode OLED to the second power source ELVSS in response to a voltage of the first node N 1 . 
     The third transistor T 3  is connected between the second electrode of the first transistor T 1  and the first node N 1 . The gate electrode of the third transistor T 3  is connected to the ith scan line SLi. The third transistor T 3  is turned on when a scan signal is supplied to the ith scan line SLi to electrically connect the second electrode of the first transistor T 1  to the first node N 1 . Therefore, when the third transistor T 3  is turned on, the first transistor T 1  may be connected in a diode form (e.g., diode-connected). 
     The fourth transistor T 4  is connected between the first node N 1  and the initialization power supply VINT. The gate electrode of the fourth transistor T 4  is connected to the i- 1 -th scan line SLi- 1 . The fourth transistor T 4  may be turned on when a scan signal is supplied to the i- 1 -th scan line SLi- 1  to supply a voltage of the initialization power source VINT to the first node N 1 . 
     Herein, a scan signal supplied to the i-th scan line SLi may correspond to a scan signal Si output from the i-th stage of the scan driver, and a scan signal supplied to the i- 1 -th scan line SLi- 1  may correspond to a scan signal Si- 1  output from the i- 1 -th stage of the scan driver. 
     The second transistor T 2  is connected between the data line Di and the first electrode of the first transistor T 1 . A gate electrode of the second transistor T 2  is connected to the i-th scan line SLi. The second transistor T 2  may be turned on when a scan signal is supplied to the i-th scan line SLi to electrically connect the data line DLi and the first electrode of the first transistor T 1 . 
     The storage capacitor Cst is connected between the first power supply ELVDD and the first node N 1 . The storage capacitor Cst may store a voltage corresponding to the data signal and the threshold voltage of the first transistor T 1 . 
     In some example embodiments, the number of scan signals supplied to each of the second, third, fourth, and seventh transistors T 2 , T 3 , T 4 , and T 7  and the width between the scan signals are controlled through the control of the width and/or the interval of the scan start signal. Therefore, the bias holding time of the driving transistor may be controlled. 
     As shown in  FIG. 2B , the fifth transistor T 5  and the sixth transistor T 6  are turned off in the gate-off period of the emission control signal EMi supplied to the emission control line ELi. At this time, the pixel P is set to a non-emission state. 
     Thereafter, the scan signal Si- 1  is supplied to the i- 1 -th scan line SLi- 1  to turn on the fourth transistor T 4 . When the fourth transistor T 4  is turned on, the voltage of the initialization power supply VINT is supplied to the first node N 1 . Then, the voltage of the first node N 1  is initialized to the voltage of the initializing power supply VINT. Herein, the voltage of the first node N 1  may be a gate voltage of the driving transistor (e.g., the first transistor T 1 ). Therefore, the first transistor T 1  is initialized to an on-bias state. 
     After the first node N 1  is initialized to the voltage of the initializing power supply VINT, the scan signal Si is supplied to the scan line SLi. When the scan signal is supplied to the i-th scan line Si, the second transistor T 2 , the third transistor T 3  and the seventh transistor T 7  are turned on. 
     When the third transistor T 3  is turned on, the first transistor T 1  is connected in a diode form. 
     When the second transistor T 2  is turned on, a data signal from the data line DLi is supplied to the first electrode of the first transistor T 1 . At this time, because the first node N 1  is initialized to the voltage of the initialization power supply VINT lower than the data signal, the first transistor T 1  is turned on. When the first transistor T 1  is turned on, a voltage obtained by subtracting the threshold voltage of the first transistor T 1  from the data signal is supplied to the first node N 1 . The storage capacitor Cst stores a voltage corresponding to the data signal supplied to the first node N 1  and the threshold voltage of the first transistor T 1 . At this time, the first transistor T 1  may have a gate-source voltage of about 0V and a drain-source voltage of about 0V. Therefore, the first transistor Ti may be in an off-bias state (or a threshold voltage bias state) in which the gate-source voltage of about 0 V and the drain-source voltage of about 0 V are supplied. 
     When the seventh transistor T 7  is turned on, the voltage of the initialization power supply VINT is supplied to the anode electrode of the organic light emitting diode OLED. That is, the voltage of the anode electrode of the organic light emitting diode OLED may be initialized. Then, a parasitic capacitor formed in the organic light emitting diode OLED is discharged, thereby improving a black display capability. When the parasitic capacitor of the organic light emitting diode OLED is discharged, a leakage current of the first transistor T 1  precharges the parasitic capacitor of the organic light emitting diode OLED so that the organic light emitting diode OLED may maintain a non-emission state (e.g., a black state). 
     After the voltage corresponding to the data signal and the threshold voltage of the first transistor T 1  are stored in the storage capacitor Cst, the emission control signal EMi supplied to the i-th emission control line ELi has a gate-on voltage, and the gate-on period may be started. At this time, the fifth transistor T 5  and the sixth transistor T 6  are turned on. Then, a current path is formed from the first power source ELVDD to the second power source ELVSS via the fifth transistor T 5 , the first transistor T 1 , the sixth transistor T 6  and the organic light emitting diode OLED. At this time, the first transistor T 1  controls the amount of current flowing to the organic light emitting diode OLED corresponding to the voltage of the first node N 1 . The organic light emitting diode OLED generates light of a predetermined luminance corresponding to the amount of current supplied from the first transistor T 1 . 
     In practice, the pixel P generates light of a predetermined luminance while repeating the process described above. In addition, a circuit structure of the pixel P in an example embodiment of the present invention is not limited to  FIG. 2A , and may be implemented with various types of circuits known in the art. 
     The emission control signal EMi is supplied to overlap with at least one scan signal so that the pixel P is set to the non-emission state during the period in which the data signal is charged in the pixel P. A supply timing of such a emission control signal EMi may be set by various methods known in the art. 
     According to some example embodiments, a length of the gate-off period of the emission control signal EMi, the number of the scan signals Si- 1  and Si, and a width of the scan signals Si- 1  and Si may be controlled based on the dimming level. 
       FIG. 3  is a block diagram showing an example of a scan driver included in the display device of  FIG. 1 , and  FIGS. 4A and 4B  are waveform diagrams showing examples of an operation of the scan driver of  FIG. 3 . 
     Referring to  FIGS. 3 to 4B , the scan driver  200  may include the first to n-th stages SST 1  to SSTn connected to the scan lines SL 1  to SLn, respectively. The scan driver  200  may output the scan signals S 1 , S 2 , . . . based on the scan start signal SFLM and the first and second clock signals CLK 1  and CLK 2 . 
     Each of the stages SST 1  to SSTn may be supplied with first and second clock signals CLK 1  and CLK 2 , and may supply scan signals S 1 , S 2 , . . . to each of the scan lines SL 1  to SLn in response to the scan start signal SFLM. 
     For example, the first stage SST 1  may supply the first scan signal S 1  to the first scan line SL 1  in response to the scan start signal SFLM. The second stage SST 2  may supply the second scan signal S 2  to the second scan line SL 2  in response to the first scan signal S 1 . 
     Herein, the number of each of the scan signals S 1 , S 2 , . . . supplied to each of the scan lines SL 1  to SLn may be determined corresponding to the width W of the scan start signal SFLM. For example, a larger number of scan signals S 1 , S 2 , . . . may be supplied to the scan lines SL 1  to SLn as the width W of the scan start signal SFLM increases. 
     The scan start signal SFLM may be supplied to the first stage SST 1  with a predetermined width in response to the dimming level. At this time, the first stage SST 1  may supply the first clock signal CLK 1  overlapping the scan start signal SFLM to the first scan line SL 1  as the first scan signal S 1 . 
     For example, as shown in  FIG. 4A , the first stage SST 1  may supply three first scan signals S 1  which overlaps the scan start signal SFLM to the first scan line SL 1 . The second stage SST 1  may receive the three first scan signals S 1 , and may output the second scan signals S 2  corresponding to the second clock signal CLK 2  delayed by half a period of the first clock signal CLK 1  to the second scan line SL 2 . Therefore, the number of the second scan signals S 2  is the same as the number of the first scan signals S 1 . Accordingly, the scan signals having the same number may be sequentially supplied to the scan lines SL 1  to SLn. 
     In addition, in one frame period, the scan start signal SFLM may include a plurality of gate-on periods. For example, as shown in  FIG. 4B , the scan signal SFLM may have a first gate-on period GO 1  and a second gate-on period GO 2 . The width of the first gate-on period GO 1  and the width of the second gate-on period GO 2  may be equal to each other or may be different from each other. In one frame period, the interval at which the scan signal (e.g., S 1 ) is supplied to one scan line (e.g., SL 1 ) may be determined corresponding to the interval between the gate-on periods of the scan start signal SFLM. 
     For example, in the first gate-on period GO 1 , one first scan signal S 1  may be supplied to the first scan line SL 1  in response to the scan start signal SFLM. In the second gate-on period GO 2 , two first scan signals S 1  may be supplied to the first scan line SL 1  in response to the scan start signal SFLM. 
     The timing of providing the scan signals supplied to each of the scan lines S 1  to Sn by the interval T between the first gate-on period GO 1  and the second gate-on period GO 2  of the scan start signal SFLM, may be changed. For example, in one frame period, one scan signal S 1  may be supplied to the first scan line SL 1  and two scan signals S 1  may be further supplied after a predetermined time elapses. During a time corresponding to the interval T between the first gate-on period GO 1  and the second gate-on period GO 2 , the transistors of the pixel to which the scan signal is supplied have a turn-off state, and the driving transistor (e.g., the first transistor, T 1 ) of the pixel may have an off-bias state. 
     On/off of the transistors is controlled by a scan signal supplied to the pixel P. In some example embodiments of the present invention, as shown in  FIG. 2A , the transistors of the pixel P may be composed of a PMOS transistor. For example, when the scan signal S 1  is supplied to the first scan line SL 1  to turn on the fourth transistor T 4 , the first transistor T 1  (e.g., the driving transistor) is in an on-bias state and a characteristic graph of the first transistor T 1  (e.g., a characteristic graph of a drain current according to a gate-source voltage) is shifted in the negative direction. On the contrary, when the scan signal S 1  is supplied to the first scan line SL 1  and a turn-off state of the transistors is kept long, the first transistor T 1  is in an off-bias state (or a threshold voltage bias state), and the characteristic graph is shifted in the positive direction. Accordingly, some example embodiments of the present invention may display a high-quality image using the characteristic change of the first transistor T 1  according to the change of the bias state by controlling the output of the scan signal. That is, by controlling the time and/or the number that the first transistor T 1  has the on-bias state and the threshold voltage bias state in one frame period, a color drag, afterimage, or the like due to abrupt gradation change or luminance change may be reduced. 
       FIG. 5  is a waveform diagram showing an example of scan signals supplied to a display panel of the display device of  FIG. 1 . 
     Referring to  FIG. 5 , the data signal DATA may be supplied to the display panel  100  in synchronization with the last scan signal supplied to one scan line in one frame period. 
     As described above, in one frame period, the scan start signal SFLM may include a plurality of gate-on periods GO 1  and GO 2 , and the scan driver  200  may supply a plurality of scan signals at a predetermined interval to one scan line based on the scan start signal SFLM. For example, as shown in  FIG. 5 , for one scan line, one scan signal may be output and two scan signals may be output after a predetermined bias time BT has elapsed. The data driver  400  may supply data signals DS 1  corresponding to the first horizontal line of the pixels to the data lines D 1  to Dm so as to be synchronized with the last first scan signal among the first scan signals S 1  supplied to the first scan line. Thereafter, the data driver  400  may sequentially supply the data signals DS 2 , DS 3 , . . . corresponding to the next horizontal lines to the data lines D 1  to Dm. 
     The data signals DS 1 , DS 2 , DS 3 , . . . from the data driver  400  may be supplied to the display panel  100  corresponding to the scan signals S 1 , S 2 , S 3  supplied sequentially so that the display panel  100  may display a predetermined image corresponding to the data signals DS 1 , DS 2 , DS 3 , In addition, the data driver  400  may supply a dummy data signal DDS before the data signal DS 1  corresponding to the first horizontal line is supplied. The dummy data signal DDS may be selected as any one of the data signals which may be supplied from the data driver  400 . 
       FIGS. 6A to 6D  are waveform diagrams showing examples of an operation of the display device of  FIG. 1  based on a dimming level according to the embodiments of the present invention. 
     Referring to  FIGS. 6A to 6D , the timing controller  500  may control the emission control start signal EFLM and the scan start signal SFLM according to the dimming level DIM. 
     In some example embodiments, as shown in  FIG. 6A , when a current dimming level DIM corresponds to the predetermined reference dimming level R_DIM, the gate-off period of the emission control start signal EFLM may have the first off-width E_OFF 1 . For example, the reference dimming level R_DIM may be set to a maximum luminance of about 100 nit. At a low-luminance lower than the reference dimming level R_DIM, the dimming may be controlled by a length of an emission period (i.e., a control of an off duty ratio). That is, the reference dimming level R_DIM refers to a reference luminance for starting dimming by controlling the length of the emission period. 
     In addition, the width of the emission control signal EM 1  supplied to the first emission control line may be substantially equal to the width of the emission control start signal EFLM. On the other hand, the first off-width E_OFF 1  of the emission control start signal EFLM refers to a non-emission period in one frame period. 
     In addition, when the dimming level DIM corresponds to the predetermined reference dimming level R_DIM, the interval between the first gate-on period GO 1  and the second gate-on period GO 2  of the scan start signal SFLM may be set to have the first interval T 1 . For example, the first gate-on period GO 1  of the scan start signal SFLM may correspond to one scan signal and the second gate-on period GO 2  of the scan start signal SFLM may correspond to two scan signals. However, the number of gate-on periods of the scan start signal SFLM, the width of each gate-on period, and the interval between the gate-on periods are not limited thereto. 
     For example, the scan driver  200  may supply j (j is a positive integer) scan signals to each of the scan lines in response to the first gate-on period GO 1  of the scan start signal SFLM, and the scan driver  200  may supply k (k is an integer of 2 or more) scan signals to each of the scan lines in response to the second gate-on period GO 2 . In this case, as shown in  FIG. 6A to 6C , as the width of the first gate-on period GO 1  and/or the width of the second gate-on period GO 1  increases, the number of scan signals supplied to each of the scan lines may increase. 
     The driving method of  FIG. 6A  is a driving method capable of maintaining a threshold voltage bias state (e.g., an off-bias state) for a sufficient time (e.g., the bias holding time BT 1  corresponding to the interval T 1  between the first gate-on period GO 1  and the second gate-on period GO 2 ) after the scan signal is supplied in the first gate-on period GO 1  to initialize the first transistor (T 1 , driving transistor) of the pixel to the on-bias state. Therefore, a hysteresis of the first transistor may be removed before a substantial data signal is supplied to a corresponding horizontal line. That is, in the first gate-on period GO 1 , a characteristic curve of the first transistor T 1  is shifted in the negative direction and the first transistor T 1  is initialized by an on-bias, and in the bias holding time BT 1 , the first transistor T 1  maintains an initialized state as a threshold voltage bias state, so that the characteristic curve is shifted again in the positive direction and the hysteresis and the emission delay may be reduced. For example, the threshold voltage bias may correspond to a voltage value corresponding to about 150 gray levels. Therefore, when the gradation rapidly changes from a low gradation (e.g., a black gradation) to a high gradation (e.g., a white gradation) in a low-luminance region of 100 nit or less, the hysteresis and the emission delay may be reduced by the control of an output of the scan signal by a setting of the first gate-on period GO 1  and the second gate-on period GO 2 , and display defects such as an afterimage, a color drag, or the like may be reduced. 
     In this case, the data signal corresponding to the horizontal line in response to the last scan signal of each of the scan signals S 1  and S 2  is supplied. 
     As shown in  FIG. 6B , when the dimming level DIM is lower than the reference dimming level R_DIM, the gate-off period of the emission control start signal EFLM may be wider than the first off-width E_OFF 1 . In addition, the interval between the first gate-on period GO 1  and the second gate-on period GO 2  may be a second interval T 2  larger than the first interval T 1 . 
     In the case of an ultralow-luminance emission in which the dimming level DIM is lower than the reference dimming level R_DIM, display defects such as a color drag, an afterimage, or the like are observed more easily by the user. To remedy this problem, in some example embodiments of the present invention, when the dimming level DIM is lower than the reference dimming level R_DIM, the larger the interval T 2  between the first gate-on period GO 1  and the second gate-on period GO 2  may increase as the dimming level DIM decrease. Therefore, the bias holding time BT 2  in a low-luminance dimming period in which the dimming level is lower than the reference dimming level R_DIM becomes longer than the bias holding time BT 2  of the reference dimming level R_DIM. 
     Therefore, display defects such as a color drag or the like due to abrupt changes from a low gradation (e.g., a black gradation) to a high gradation (e.g., a white gradation) may be reduced. 
     In some example embodiments, the width of at least one of the first gate-on period GO 1  and the second gate-on period GO 2  may increase according to a predetermined dimming level DIM as the dimming level DIM decreases. 
     As shown in  FIG. 6C , when the dimming level DIM is higher than the reference dimming level R_DIM, the gate-off period of the emission control start signal EFLM may be set to the second off-width E_OFF 2  narrower than the first off-width E_OFF 1 . In addition, the first gate-on period GO 1  and the second gate-on period GO 2  may be continuous with each other. For example, when the display panel  100  emits light with a luminance larger than 100 nit, the timing controller  500  may successively output the first gate-on period GO 1  and the second gate-on period GO 2  in one frame period. That is, the scan start signal SFLM may be output with one gate-on interval in which the first gate-on period GO 1  and the second gate-on period GO 2  are continuous. In some example embodiments, the width of the first gate-on period GO 1  and the second gate-on period GO 2  which are continuous may be substantially equal to the sum of the width of the first gate-on period GO 1  and the width of the second gate-on period GO 2  in  FIGS. 6A and 6B . However, this embodiment is only an example, and when the dimming level DIM is higher than the reference dimming level R_DIM, the width of the gate-on period of the scan start signal SFLM may be smaller than the sum of the width of the first gate-on period GO 1  and the width of the second gate-on period GO 2 . 
     In some example embodiments, when the dimming level DIM is higher than the reference dimming level R_DIM, a dimming by controlling an off-duty ratio of the emission control signal is not performed. Therefore, the second off-width E_OFF 2 , which is the width of the gate-off period of the emission control start signal EFLM, may be constant regardless of a change in the dimming level DIM. Further, when the dimming level DIM is higher than the reference dimming level R_DIM, the width of the first gate-on period GO 1  and the width of the second gate-on period GO 2  may be constant regardless of the dimming level DIM. In the case of a high-luminance emission in which the dimming level DIM is higher than the reference dimming level R_DIM, the color drag or the afterimage due to the hysteresis is not well observed, so that the bias holding time of the scan signals S 1  and S 2  is not set in the present embodiment. 
     In some example embodiments, as shown in  FIG. 6D , when the dimming level DIM is higher than the reference dimming level R_DIM, the interval between the first gate-on period GO 1  and the second gate-on period GO 2  may be the third interval T 3  smaller than the first interval T 1 . Therefore, even at a high-luminance emission in which the dimming level is higher than the reference dimming level (R_DIM), a predetermined bias holding time BT 3  may be ensured. 
     As described above, the display device  100  according to some example embodiments of the present invention may improve poor visibility due to an abrupt gradation change in the low-luminance region by controlling the interval between the gate-on periods GO 1  and GO 2  of the scan control signal SFLM in the low-luminance region based on the dimming level. 
       FIG. 7  is a block diagram showing an example of an emission driver included in the display device of  FIG. 1 , and  FIGS. 8A and 8B  are waveform diagrams showing examples of an operation of the emission driver of  FIG. 7 . 
     Referring to  FIGS. 7 to 8B , the emission driver  300  may include the first to n-th stages EST 1  to ESTn connected to the emission control lines EL 1  to ELn, respectively. The emission driver  300  may output the emission control signals EM 1 , EM 2 , . . . based on the emission control start signal EFLM and the third and fourth clock signals CLK 3  and CLK 4 . 
     The first stage EST 1  may supply the first emission control signal EM 1  to the first emission control line EL 1  in response to the emission control start signal EFLM. The second stage EST 2  may supply the second emission control signal EM 2  to the second emission control line EL 2  in response to the first emission control signal EM 1 . 
     In this case, as shown in  FIGS. 8A and 8B , the width of the gate-off period of the emission control signals EM 1 , EM 2 , . . . may be determined corresponding to the width of the gate-off period E_OFF of the emission control start signal EFLM. That is, the width of the emission control signals EM 1 , EM 2 , . . . is set to be wider as the width of the emission control start signal EFLM becomes wider. The width of the gate-off period E_OFF of the emission control start signal EFLM may be determined by the dimming level. 
       FIGS. 9A to 9C  are block diagrams showing examples of a timing controller included in the display device of  FIG. 1 . 
     Referring to  FIGS. 9A to 9C , the timing controller  500 ,  501 , and  502  may include a first start signal determiner  520  and a second start signal determiner  540 ,  541 , and  542 . 
     The first start signal determiner  520  may determine the width of the gate-off period of the emission control start signal EFLM based on the dimming signal DIS including information of the dimming level. The dimming signal DIS may include one of information of a predetermined dimming level. In some example embodiments of the present invention, the first start signal determiner  520  may determine the emission control start signal EFLM from a look-up table storing the relationship between the dimming level and the width of the gate-off period of the emission control start signal EFLM. However, the configuration in which the first start signal determiner  520  determines the gate-off period of the emission control start signal EFLM is not limited to this example embodiment. 
     The second start signal determiner  540 ,  541 ,  542  may determine the width of the scan start signal SFLM (i.e., the width of the gate-on period), the number of gate-on periods of the scan start signal SFLM, and the interval between the gate-on periods based on at least one of the dimming signal DIS and the emission control start signal EFLM. For example, as shown in  FIG. 9A , the second start signal determiner  540  may determine the interval between the first gate-on period and the second gate-on period of the scan start signal SFLM in response to the dimming signal DIS. 
     As another example, as shown in  FIG. 9B , the second start signal determiner  541  may determine an interval between the first gate-on period and the second gate-on period of the scan start signal SFLM based on the width of the gate-off period of the emission control start signal EFLM. In this case, the second start signal determiner  541  may receive information related to the emission control start signal EFLM from the first start signal determiner  520 . 
     As another example, as shown in  FIG. 9C , the second start signal determiner  542  may determine an interval between the first gate-on period and the second gate-on period of the scan start signal SFLM referring to both the emission control start signal EFLM and the dimming signal DIS. 
     In some example embodiments, the second start signal determiner  542  may output one scan start signal SFLM and may determine the width of the scan start signal SFLM based on at least one of the emission control start signal EFLM and the dimming signal DIS. 
     The contents related to a control of the scan start signal SFLM and the emission control start signal EFLM based on the dimming level have been described above with reference to  FIGS. 6A to 6D , and a duplicate description thereof will be omitted. 
     As described above, by controlling the waveforms of the scan start signal SFLM and the emission control start signal EFLM based on the dimming level, display defects due to a gradation change in a low-luminance emission may be reduced. 
       FIGS. 10A to 10C  are waveform diagrams showing another examples of an operation of the display device of  FIG. 1  based on a dimming level according to the embodiments of the present invention. 
     In  FIGS. 10A to 10C , the same reference numerals are used for the same elements as those described referring to  FIGS. 6A to 6D , and a duplicate description will be omitted. 
     Referring to  FIGS. 10A to 10C , the timing controller  500  may control the emission control start signal EFLM and the scan start signal SFLM according to on the dimming level DIM. 
     In some example embodiments, the timing controller  500  may control the width of the scan start signal SFLM (i.e., the width of the gate-on period of the scan start signal SFLM) in the non-emission period based on the dimming level DIM. The number of scan signals supplied to the scan lines SL 1  to SLn may change based on the width of the scan start signal SFLM. 
     When the dimming level DIM corresponds to the reference dimming level R_DIM, the gate-off period of the emission control start signal EFLM has the first width. When the dimming level DIM is lower than the reference dimming level R_DIM, the width of the gate-off period of the emission control start signal EFLM increases to a predetermined width as the dimming level DIM decreases. When the dimming level DIM is higher than the reference dimming level R_DIM, the width of the gate-off period of the emission control start signal EFLM has the second width smaller than the first width regardless of the dimming level DIM. 
     As shown in  FIG. 10A , when the current dimming level DIM corresponds to the predetermined reference dimming level R_DIM, the scan start signal SFLM may have the first width W 1 . For example, five first scan signals S 1  may be output in response to the scan start signal SFLM. In this case, the data signal corresponding to the first horizontal line may be output from the data driver  400  in synchronization with the last scan signal of the first scan signal S 1 . 
     Therefore, the number of initialization of the on-bias state for the driving transistor of the pixel may increase, and the hysteresis of the driving transistor may be eliminated or reduced. 
     As shown in  FIG. 10B , when the dimming level DIM is included in the first dimming period lower than the reference dimming level R_DIM, the scan start signal SFLM may have a second width W 2  larger than the first width W 1 . Therefore, the number of scan signals supplied to one scan line in the first dimming period is larger than the number of scan signals at the reference dimming level R_DIM. For example, seven first scan signals S 1  may be output corresponding to the scan start signal SFLM at a predetermined dimming level DIM included in the first dimming period. In some example embodiments, in the first dimming period, the width of the scan start signal SFLM may increase as the dimming level DIM becomes lower. That is, as the dimming level DIM becomes lower, the number of scan signals supplied to each of the output scan lines may increase. Therefore, the hysteresis of the driving transistor is removed, and display defects such as a color drag and an afterimage at a low-luminance may be reduced. 
     As shown in  FIG. 10C , when the dimming level DIM is included in the second dimming period higher than the reference dimming level R_DIM, the scan start signal SFLM may have the third width W 3  smaller than the first width W 1 . In the case of a high-luminance emission, the number of scan signals supplied to each of scan lines is reduced because a color drag due to a grayscale change is relatively not observed. 
     As described above, by increasing the width of the scan start signal in a low-luminance region below the reference dimming level R_DIM referring to the dimming level, the number of scan signals supplied to each of scan lines may increase. As a result, the number of on-bias of the driving transistor in the low-luminance region increases, so that the display defects due to the hysteresis and the emission delay may be reduced. 
       FIGS. 11A to 11C  are waveform diagrams showing another examples of an operation of the display device of  FIG. 1  based on a dimming level according to the embodiments of the present invention. 
     In  FIGS. 11A to 11C , the same reference numerals are used for the same elements as those described referring to  FIGS. 6A to 6D , and a duplicate description will be omitted. 
     Referring to  FIGS. 11A to 11C , the timing controller  500  may control the emission control start signal EFLM and the scan start signal SFLM according to the dimming level DIM. 
     In some example embodiments, the timing controller  500  may control the width of the gate-on periods GO 1  and GO 2  and the intervals T 1  and T 2  between the gate-on periods GO 1  and GO 2  of the scan start signal SFLM according to the dimming level DIM. 
     For example, as shown in  FIG. 11A , when the dimming level DIM corresponds to the reference dimming level R_DIM, the first gate-on period GO 1  of the scan start signal SFLM may overlap one scan signal S 1  of the first scan line S 1 , the second gate-on period GO 2  may overlap three scan signals of the first scan line, and the interval between the first gate-on period GO 1  and the second gate-on period GO 2  may be the first interval T 1 . 
     Meanwhile, as shown in  FIG. 11B , when the dimming level DIM is lower than the reference dimming level R_DIM, the first gate-on period GO 1  of the scan start signal SFLM may overlap one scan signal S 1  of the first scan line, the second gate-on period GO 2  may overlap five scan signals of the first scan line, and the interval between the first gate-on period GO 1  and the second gate-on period GO 2  may be the second interval T 2  larger than the first interval T 1 . 
     As described above, as the dimming level DIM decreases, the number of scan signals supplied to each of scan lines and the interval between gate-on periods increase, so that poor visibility due to an abrupt gradation change in a low-luminance may be improved. 
     Further, as shown in  FIG. 11C , in the case of a medium luminance or more in which the dimming level DIM is higher than the reference dimming level R_DIM, the first gate-on period GO 1  and the second gate-on period GO 2  of the scan start signal SFLM may be continuous, and the total width W 3  of the scan start signal SFLM may also be set to be smaller than the sum of the gate-on periods at the reference dimming level R_DIM. 
       FIGS. 12A and 12B  are waveform diagrams showing another example of an operation of the display device of  FIG. 1  based on a dimming level. 
     In  FIGS. 12A and 12B , the same reference numerals are used for the same elements as those described referring to  FIGS. 11A to 11B , and a duplicate description will be omitted. 
     Referring to  FIGS. 12A and 12B , below the reference dimming level R_DIM, the widths of the gate-on periods GO 1  and GO 2  of the scan start signal SFLM and the intervals T 1  and T 2  between the gate-on periods GO 1  and GO 2  may be controlled. 
     For example, as the dimming level DIM decreases, the width of the first gate-on period GO 1  may decrease while the width of the second gate-on period GO 2  may increase. In addition, as the dimming level DIM decreases, the intervals T 1  and T 2  between the first gate-on period GO 1  and the second gate-on period GO 2  may increase. 
     The initialization of the on-bias state in each horizontal line may be performed differently in response to the first gate-on period GO 1  of the scan start signal SFLM according to the dimming level DIM. For example, as shown in  FIG. 12A , in the reference dimming level R_DIM, two scan signals may be output corresponding to the first gate-on period GO 1 , and as shown in  FIG. 12B , when the dimming level R_DIM is lower than the reference dimming level R_DIM, one scan signal may be output corresponding to the first gate-on period GO 1 . 
     In addition, as shown in  FIGS. 12A and 12B , the bias holding time BT 1  in each horizontal line may be applied differentially in response to the first gate-on period GO 1  and the second gate-on period GO 2  of the scan start signal SFLM according to the dimming level DIM. 
     As described above, the display device  1000  according to some example embodiments of the present invention and timing controller  500  included therein may increase at least one of the interval between the gate-on periods and the width of the gate-on period of the scan start signal as the dimming level DIM becomes lower. Therefore, the number and a supplying interval of scan signals supplied to the pixels during the non-emission period may be controlled based on the dimming level DIM, the hysteresis of the driving transistor included in the pixel is eliminated, and the emission delay of a specific pixel may be reduced. 
       FIG. 13  is a block diagram showing a display device according to some example embodiments of the present invention. 
     Because the display device  1001  of  FIG. 13  is the same as the display device of  FIG. 1  except for a configuration of the scan drivers, like reference numerals are used for like or corresponding elements, and a duplicate description thereof will be omitted. 
     Referring to  FIGS. 2A and 13 , the display device  1001  may include a display panel  100 , a first scan driver  200 ′, a second scan driver  700 , an emission driver  300 , a data driver  400 , and a timing controller  500 ′. 
     The first scan driver  200 ′ and the second scan driver  700  may generate a scan signal corresponding to the i- 1 -th scan line and a scan signal corresponding to the i-th scan line of the pixel P of  FIG. 2A  based on the first scan start signal SFLM 1  and the second scan start signal SFLM 2 , respectively. For example, the scan signal output from the first scan driver  200 ′ may be supplied to the fourth transistor T 4  of each pixel through the first scan lines SL 1  to SLn, and the scan signal output from the second scan driver  700  may be supplied to the second, third and seventh transistors T 2 , T 3  and T 7  of each pixel through the second scan lines GL 1  to GLn. Therefore, the first scan driver  200 ′ may control an on-bias state of the driving transistor of the pixel, and the second scan driver  700  may control an off-bias state of the driving transistor of the pixel. 
     Because an operation of each of the first scan driver  200 ′ and the second scan driver  700  is the same as that described above, a detailed description thereof will be omitted. 
       FIG. 14  is a block diagram showing a display device according to some example embodiments of the present invention. 
     Because the display device  1002  of  FIG. 14  is the same as the display device of  FIG. 1  except for a configuration of the emission drivers, like reference numerals are used for like or corresponding elements, and redundant explanations are omitted. 
     Referring to  FIG. 14 , the display device  1002  may include a display panel  100 , a scan driver  200 , a first emission driver  300 , a second emission driver  300 ′, a data driver  400 , and a timing controller  500 ″. 
     In the display device  1002 , the first emission driver  300  and the second emission driver  300 ′ may be arranged at both sides of the display panel  100 . Because an operation of each of the first emission driver  300  and the second emission driver  300 ′ is the same as that described above, a detailed description thereof will be omitted. 
     As described above, the display devices  1000 ,  1001  and  1002  according to some example embodiments of the present invention may reduce display defects such as a color drag and an afterimage due to an abrupt gradation change at low-luminance by controlling the number and supplying interval of scan signals supplied to the pixel during the non-emission period and the scan signal application intervals based on the dimming level DIM. 
     The display device according to some example embodiments of the present invention may be applied to various electronic devices. For example, the display device may be applied to an HMD device, a TV, a digital TV, a 3D TV, a PC, a home electronic device, a notebook computer, a tablet computer, a mobile phone, a smart phone, a PDA, a PMP, a digital camera, a music player, a portable game console, a navigation device, a wearable device, and the like. 
     The electronic or electric devices and/or any other relevant devices or components according to embodiments of the present invention described herein may be implemented utilizing any suitable hardware, firmware (e.g. an application-specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, the various components of these devices may be formed on one integrated circuit (IC) chip or on separate IC chips. Further, the various components of these devices may be implemented on a flexible printed circuit film, a tape carrier package (TCP), a printed circuit board (PCB), or formed on one substrate. Further, the various components of these devices may be may be a process or thread, running on one or more processors, in one or more computing devices, executing computer program instructions and interacting with other system components for performing the various functionalities described herein. The computer program instructions are stored in a memory which may be implemented in a computing device using a standard memory device, such as, for example, a random access memory (RAM). The computer program instructions may also be stored in other non-transitory computer readable media such as, for example, a CD-ROM, flash drive, or the like. Also, a person of skill in the art should recognize that the functionality of various computing devices may be combined or integrated into a single computing device, or the functionality of a particular computing device may be distributed across one or more other computing devices without departing from the spirit and scope of the exemplary embodiments of the present invention. 
     While the present invention has been shown and described with reference to certain example embodiments thereof, it will be understood by those skilled in the art that various changes in forms and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims and their equivalents.