Patent Publication Number: US-9852698-B2

Title: Display apparatus and driving method thereof using a time/space division scheme

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from and the benefit of Korean Patent Application No. 10-2013-0127432, filed on Oct. 24, 2013, which is hereby incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND 
     Field 
     Exemplary embodiments of the present invention relate to a display device and a driving method thereof. 
     Discussion of the Background 
     As a flat panel display device, a liquid crystal display device may realize full color using a space division scheme. For this, a liquid crystal display panel may include red, green, and blue color filters that are iteratively arranged to correspond to each sub pixel in a one-to-one manner. A unit combination of red, green, and blue color filters may form a minimum unit for color realization, and full color may be implemented through a transmissivity difference between sub pixels of the liquid crystal display panel and a color combination of red, green, and blue color filters. The red, green, and blue color filters may be disposed at different spaces within the liquid crystal display panel. This may be referred to as a space division scheme. 
     By comparison, a time division scheme (or, a field sequential scheme) may implement a full color with high transmissivity and a low manufacturing cost. With the time division scheme, the liquid crystal display panel may not include a color filter, and red, green, and blue light sources may be disposed on the rear of the liquid crystal display panel to emit red, green, and blue color lights. Also, a unit frame may be divided into three sub-frames in time, and the red, green, and blue light sources may be on every sub frame such that red, green, and blue color images are sequentially realized. Thus, a viewer may recognize a full-color image such that red, green, and blue color images are mixed as a result of physiological visual sensation. 
     A conventional time division type liquid crystal display device may be advantageous in reducing manufacturing costs and improving transmissivity. On the other hand, a color breakup phenomenon in which red, green, and blue color images are separately recognized for an instant, resulting from eye blinking or the movement of either picture or viewer, may appear. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and, therefore, it may contain information that does not constitute prior art. 
     SUMMARY 
     Exemplary embodiments of the present invention provide a display device capable of providing full color on a display panel using a time/space division scheme. 
     Exemplary embodiments of the present invention also provide a method of driving a display device in which turn-on times of first and second light sources of a backlight unit may be adjusted according to a color characteristic of an image being displayed. 
     Additional features of the invention will be set forth in the description which follows, and in part will become apparent from the description, or may be learned from practice of the invention. 
     An exemplary embodiment of the present invention discloses a display device including a display panel; a display panel driving unit configured to convert an image signal provided from an external device into a data signal such that an image is displayed on the display panel, and to output a first light control signal and a second light control signal; and a backlight unit configured to provide the display panel with a first color light and a second color light different from the first color light in response to the first light control signal and the second control signal. The display panel driving unit is further configured to determine a pulse width of each of the first light control signal and the second light control signal according to a color characteristic of the image signal. 
     An exemplary embodiment of the present invention also discloses a method of driving a display device, the method including receiving an image signal; determining a pulse width of each of first light source control signals and second light source control signals according to a color characteristic of the image signal; and providing a first color light and a second color light during a time period corresponding to a pulse width of each of the first light source control signals and the second light source control signals. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention, and together with the description serve to explain the principles of the invention. 
         FIG. 1  is a block diagram schematically illustrating a display device according to an exemplary embodiment of present invention. 
         FIG. 2  is a diagram showing a full-color realizing principle using a time/space division scheme of the display device shown in  FIG. 1 . 
         FIG. 3  is a diagram schematically illustrating the display panel shown in  FIG. 1 . 
         FIG. 4  is a diagram schematically illustrating an arrangement of light sources in the backlight unit shown in  FIG. 1 , according to an exemplary embodiment of the present invention. 
         FIG. 5  is a diagram schematically illustrating an arrangement of light sources in the backlight unit shown in  FIG. 1 , according to an exemplary embodiment of the present invention. 
         FIG. 6  is a block diagram schematically illustrating the backlight unit shown in  FIG. 1 . 
         FIG. 7  is a timing diagram showing signals provided from the timing controller shown in  FIG. 1  to the backlight controller shown in  FIG. 6 . 
         FIG. 8  is a block diagram schematically illustrating the timing controller shown in  FIG. 1 . 
         FIG. 9  is a block diagram schematically illustrating the backlight control unit shown in  FIG. 8 . 
         FIG. 10  is a diagram showing a frame of an image signal provided to the image splitter shown in  FIG. 9 , according to an exemplary embodiment of the present invention. 
         FIG. 11  is a diagram showing an image corresponding to a preselected display block in the display panel shown in  FIG. 3 , from the image shown in  FIG. 10 . 
         FIGS. 12A and 12B  are diagrams showing a histogram analysis result of the image analyzer shown in  FIG. 9  on an image corresponding to the preselected display block shown in  FIG. 11 . 
         FIGS. 13 to 16  are diagrams for describing a technique of setting pulse widths of first light source control signals and second light source control signals according to color characteristics of various image groups. 
         FIGS. 17 to 21  are diagrams schematically illustrating a crystal transmittance ratio which is varied whenever pulse widths of first and second light control signals are varied. 
         FIG. 22  is a diagram schematically illustrating an image signal of  FIG. 10  displayed on a display panel when the timing controller shown in  FIG. 1  operates in a first mode at a default state. 
         FIG. 23  is a diagram schematically illustrating an image signal of  FIG. 10  displayed on a display panel when the timing controller shown in  FIG. 1  operates according to an image type of an image signal. 
         FIG. 24  is a diagram schematically illustrating a mixing ratio of a yellow color and a blue color of an image displayed on a display panel shown in  FIGS. 22 and 23  according to an operation state of the timing controller shown in  FIG. 1 . 
         FIG. 25  is a diagram schematically illustrating turn-on time periods, expressed as LED duty cycle, of first and second light sources when an image illustrated in  FIGS. 22 and 23  is displayed on a display pane according to an operation state of the timing controller shown in  FIG. 1 . 
         FIG. 26  is a diagram schematically illustrating an image signal (including a red color and a yellow color) displayed on a display panel when the timing controller shown in  FIG. 1  operates in a first mode at a default state. 
         FIG. 27  is a diagram schematically illustrating an image signal (including a red color and a yellow color) displayed on a display panel when the timing controller shown in  FIG. 1  operates according to an image type of an image signal. 
         FIG. 28  is a diagram schematically illustrating a mixing ratio of a yellow color and a blue color of an image displayed on a display panel shown in  FIGS. 26 and 27  according to an operation state of the timing controller shown in  FIG. 1 . 
         FIG. 29  is a diagram schematically illustrating turn-on time periods, expressed as LED duty cycle, of first and second light sources when an image illustrated in  FIGS. 26 and 27  is displayed on a display pane according to an operation state of the timing controller shown in  FIG. 1 . 
         FIG. 30  is a block diagram schematically illustrating a display device according to an exemplary embodiment of the present invention. 
         FIG. 31  is a diagram schematically illustrating an arrangement of light sources of the backlight unit shown in  FIG. 30 . 
         FIG. 32  is a block diagram schematically illustrating the backlight unit shown in  FIG. 30 . 
         FIG. 33  is a flow chart for describing a driving method of a display device according to an exemplary embodiment of the present invention. 
         FIG. 34  is a flow chart for describing a method of deciding a pulse width of each of first light source control signals and second light source control signals shown in  FIG. 33 . 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     The invention is described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of elements may be exaggerated for clarity. Like reference numerals in the drawings denote like elements. 
     It will be understood that, although the terms “first”, “second”, “third”, etc., may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the inventive concept. 
     Spatially relative terms, such as “beneath”, “below”, “lower”, “under”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” or “under” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary terms “below” and “under” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the inventive concept. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Also, the term “exemplary” is intended to refer to an example or illustration. 
     It will be understood that when an element or layer is referred to as being “on”, “connected to”, “coupled to”, or “adjacent to” another element or layer, it can be directly on, connected, coupled, or adjacent to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to”, “directly coupled to”, or “immediately adjacent to” another element or layer, there are no intervening elements or layers present. It will be understood that for the purposes of this disclosure, “at least one of X, Y, and Z” can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ). 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or the present specification and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
       FIG. 1  is a block diagram schematically illustrating a display device according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 1 , a display device  100  may include a display panel  110 , a timing controller  120 , a gate driver  130 , a data driver  140 , and a backlight unit  150 . The timing controller  120 , the gate driver  130 , and the data driver  140  may constitute a display panel driving unit that drives the display panel  110 . 
     The display panel  110  may include gate lines GL 1  to GLn extending along a first direction X1, data lines DL 1  to DLm crossing the gate lines GL 1  to GLn and extending along a second direction X2, and sub pixels SPX respectively arranged at intersections of the gate lines GL 1  to GLn and the data lines DL 1  to DLm. Here, n and m may be natural numbers not equal to 0. The gate lines GL 1  to GLn and the data lines DL 1  to DLm may be isolated from one another. 
     Each sub pixel SPX may have a switching transistor TR connected to a corresponding data line and a corresponding gate line, and a crystal capacitor CLC connected thereto. 
     The sub pixels SPX may each have the same structure. For ease of description, a single sub pixel will be described. The switching transistor TR of the sub pixel SPX may have a gate electrode connected to a gate line GL 1  of the gate lines GL 1  to GLn, a source electrode connected to a data line DL 1  of the data lines DL 1  to DLm, and a drain electrode connected to a first end of the crystal capacitor CLC. A second end of the crystal capacitor CLC may be connected to a common voltage. The switching transistor TR may be a thin film transistor. 
     The timing controller  120  may receive an image signal RGB and control signals CTRL for controlling a display of the image signal RGB from an external device. For example, the control signals CTRL may include a vertical synchronization signal, a horizontal synchronization signal, a main clock signal, a data enable signal, etc. Based on the control signals CTRL, the timing controller  120  may provide the data driver  140  with a first control signal CONT 1  and a data signal DATA, obtained by processing the image signal RGB to be suitable for an operation condition of the display panel  110 , and a second control signal CONT 2  transmitted to the gate driver  130 . The first control signal CONT 1  may include a horizontal synchronization start signal, a clock signal, and a line latch signal, and the second control signal CONT 2  may include a vertical synchronization start signal, an output enable signal, and a gate pulse signal. The timing controller  120  may output first light source control signals YCTRL 1  to YCTRL 8  and second light source control signals BCTRL 1  to BCTRL 8  to control the backlight unit  150 . 
     The data driver  140  may output gradation voltages for driving the data lines DL 1  to DLm according to the data signal DATA and the first control signal CONT 1  from the timing controller  120 . 
     The gate driver  130  may drive the gate lines GL 1  to GLn in response to the second control signal CONT 2  from the timing controller  120 . The gate driver  130  may include one or more gate driver ICs. The gate driver  130  may be implemented by not only the gate driver ICs, but also circuits using ASG (Amorphous Silicon Gate) using an amorphous Silicon Thin Film Transistor (a-Si TFT), an oxide semiconductor, a crystalline semiconductor, a polycrystalline semiconductor, etc. 
     When a gate-on voltage is applied to a gate line by gate driver  130 , a row of switching transistors connected to the gate line may be turned on. At this time, the data driver  140  may provide the data lines DL 1  to DLm with gradation voltages corresponding to a data signal DATA. The gradation voltages provided to the data lines DL 1  to DLm may be applied to corresponding sub pixels through turn-on of the switching transistors. Here, a time period in which switching transistors in a row are turned on, that is, periods of an output enable signal and a gate pulse signal, may be referred to as a 1-horizontal period or 1H. 
     The backlight unit  150  may be disposed on the rear of the display panel  110 , and may provide a light from the rear of the display panel  110 . The backlight unit  150  may include a light source formed of a plurality of light-emitting diodes (not shown). In this case, the light-emitting diodes may be arranged on a printed circuit board in a stripe shape along one direction or in a matrix shape. 
       FIG. 2  is a diagram showing a full-color realizing principle using a time/space division scheme of a display device shown in  FIG. 1 . 
     Referring to  FIG. 2 , a first color filter R and a second color filter G having different colors may be provided within a display panel  110  (refer to  FIG. 1 ) to realize full color using a time/space division scheme. For example, the first color filter R may be a red color filter having a red color, and the second color filter G may be a green color filter having a green color. However, the first color filter R and the second color filter G may not be limited to this. Assuming that an area corresponding to a pixel is defined as a pixel area PA, each pixel area PA may have the first color filter R and the second color filter G. Also, each pixel area PA may have an open portion W. The first color filter R, the second color filter G, and the open portion W may be formed sequentially along a first direction X1. The first color filter R, the second color filter G, and the open portion W may correspond to three sub pixels, respectively. The open portion W may be implemented by a transparent filter on the same surface as the first color filter R and the second color filter G. 
     A backlight unit  150  may include a first light source  151  for generating a first color light Ly, and a second light source  152  for generating a second color light Lb. A unit frame F may be temporally divided into a first sub frame SF1 and a second sub frame SF2. During a period of the first sub frame SF1, the first light source  151  of the backlight unit  150  may be driven. That is, during a period of the first sub frame SF1, the first color light Ly may be provided to the display panel  110 . Afterwards, during a period of the second sub frame SF2, the second light source  152  of the backlight unit  150  may be driven such that the second color light Lb is provided to the display panel  110 . If a frequency of the unit frame F is 60 Hz, each of the first sub frame SF1 and the second sub frame SF2 may have a frequency of 120 Hz. 
     In exemplary embodiments, the first color light Ly from the first light source  151  may be yellow, and the second color light Lb from the second light source  152  may be blue. If the first color light Ly is yellow, the first color light Ly may include red and green light components. 
     Thus, a red light component of the first color light Ly generated from the backlight unit  150  during a period of the first sub frame SF1 may pass through the first color filter R to be displayed as a red image. A green light component of the first color light Ly may pass through the second color filter G to be displayed as a green image. Also, the first color light Ly may pass through the open portion W to be displayed as a yellow image. 
     Afterwards, the second color light Lb generated from the backlight unit  150  during a period of the second sub frame SF2 may pass through the open portion W to be displayed as a blue image. 
     As described above, the open portion W may be prepared to provide a space capable of displaying a yellow image during a period of the first sub frame SF1, and a blue image during a period of the second sub frame SF2. A white may be recognized by displaying a yellow image and a blue image alternately in the time division manner. Therefore, the open portion W may eliminate a color breakup phenomenon generated as a result of time division, with a resulting improvement in luminance. A size of the open portion W may be selected to provide proper transmissivity, considering luminance and the color of a target frame. 
     Full color may be realized through a time/space division scheme by displaying a red image and a green image through the space division scheme using the first color filter R and the second color filter G, and alternately displaying a yellow image and a blue image through the time division scheme. 
       FIG. 3  is a diagram schematically illustrating the display panel  110  shown in  FIG. 1 . 
     Referring to  FIG. 3 , the display panel  110  may be divided into display blocks DBK1 to DBK8. In  FIG. 3 , for example, the display panel  110  is divided into eight display blocks DBK1 to DBK8. However, present invention is not limited thereto, and different numbers and sizes of display blocks may be made. 
       FIG. 4  is a diagram schematically illustrating an arrangement of light sources in the backlight unit shown in  FIG. 1 , according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 4 , a backlight unit  150  may be placed at the rear of a display panel  110  shown in  FIG. 3 , and may supply a light to the display panel  110 . The backlight unit  150  may include light source blocks LBK1 to LBK8 respectively corresponding to display blocks DBK1 to DBK8 of the display panel  110 . Each of the light source blocks LBK1 to LBK8 may include a plurality of first light sources  151  and a plurality of second light sources  152 . A first light source  151  and a second light source  152  that are disposed to be adjacent to each other may constitute a light source pair. Light source pairs may be arranged in a matrix shape. In exemplary embodiments, a first color light Ly from the first light source  151  may be a light having a yellow color, and a second color light Lb provided from the second light source  152  may be a light having a blue color. 
       FIG. 5  is a diagram schematically illustrating an arrangement of light sources in a backlight unit shown in  FIG. 1 , according to another exemplary embodiment of the present invention. 
     Referring to  FIG. 5 , a backlight unit  150  may be placed at the rear of the display panel  110  shown in  FIG. 3 , and may supply a light to the display panel  110 . The backlight unit  150  may include light source blocks LBK1 to LBK8 respectively corresponding to display blocks DBK1 to DBK8 of the display panel  110 . Each of the light source blocks LBK1 to LBK8 may include a plurality of first light sources  151  and a plurality of second light sources  152 . A first light source  151  and a second light source  152  that are disposed to be adjacent to each other may constitute a light source pair. Unlike a backlight unit  150  shown in  FIG. 4 , odd-numbered lines of light source pairs and even-numbered lines of light source pairs may be alternately disposed along a second direction X2 of the backlight unit  150  shown in  FIG. 5 . The arrangement of light sources LED of the backlight unit  150  shown in  FIG. 5  may be different from the arrangement of light sources LED of the backlight unit  150  shown in  FIG. 4 . However, the backlight unit  150  shown in  FIG. 5  may be the same as the backlight unit  150  shown in  FIG. 4  in that it is divided into light source blocks LBK1 to LBK8. 
       FIG. 6  is a block diagram schematically illustrating the backlight unit shown in  FIG. 1 . 
     Referring to  FIG. 6 , a backlight unit  150  may include the backlight controller  155  and light source blocks LBK1 to LBK8. The backlight controller  155  may receive first light source control signals YCTRL 1  to YCTRL 8 , and second light source control signals BCTRL 1  to BCTRL 8  from the timing controller  120  shown in  FIG. 1  to generate first light source voltages YVDD1 to YVDD8 and second light source voltages BVDD1 to BVDD8 that supply a power to light source blocks LBK1 to LBK8. 
     Each of the light source blocks LBK1 to LBK8 may include a first light source string YS, including first light sources  151  connected in series and a second light source string BS including second light sources  152  connected in series. 
     First light source strings YS in the light source blocks LBK1 to LBK8 may be supplied with first light source voltages YVDD1 to YVDD8 from the backlight controller  155 , and second light source strings BS in the light source blocks LBK1 to LBK8 may be supplied with second light source voltage BVDD1 to BVDD8 from the backlight controller  155 . 
       FIG. 7  is a timing diagram showing signals provided from the timing controller  120  shown in  FIG. 1  to the backlight controller  155  shown in  FIG. 6 . 
     Referring to  FIG. 7 , first light source control signals YCTRL 1  to YCTRL 8  provided from the timing controller  120  shown in  FIG. 1  may be sequentially activated within a period of a first sub frame SF1, and second light source control signals BCTRL 1  to BCTRL 8  may be sequentially activated within a period of a second sub frame SF2. 
     As illustrated in  FIG. 3 , the display panel  110  may be divided into display blocks DKB1 to DBK8, and gate lines GL 1  to GLn may be sequentially driven. Because light source blocks LBK1 to LBK8 shown in  FIG. 6  correspond to the display blocks DKB1 to DBK8, the first light source control signals YCTRL 1  to YCTRL 8  and the second light source control signals BCTRL 1  to BCTRL 8  may be sequentially driven. 
     In  FIG. 7 , the first light source control signals YCTRL 1  to YCTRL 8  are sequentially activated within a section of a period of the first sub frame SF1, and the second light source control signals BCTRL 1  to BCTRL 8  are sequentially activated within a section of a period of the second sub frame SF2. However, the first light source control signals YCTRL 1  to YCTRL 8  may be activated within the second sub frame SF2 as well as the first sub frame SF1. The second light source control signals BCTRL 1  to BCTRL 8  may be activated within the first sub frame SF1 as well as the second sub frame SF2. Also, active periods ty11 to ty81 of the first light source control signals YCTRL 1  to YCTRL 8  may have the same length, and active periods tb12 to tb82 of the second light source control signals BCTRL 1  to BCTRL 8  may have the same length. However, the present invention is not limited thereto. The active periods ty11 to ty81 may represent pulse widths of the first light source control signals YCTRL 1  to YCTRL 8 , respectively. The active periods tb12 to tb82 may represent pulse widths of the second light source control signals BCTRL 1  to BCTRL 8 . Below, a method of changing widths of the active periods ty11 to ty81 of the first light source control signals YCTRL 1  to YCTRL 8  and widths of the active periods tb12 to tb82 of the second light source control signals BCTRL 1  to BCTRL 8  will be described. 
       FIG. 8  is a block diagram schematically illustrating the timing controller shown in  FIG. 1 . 
     Referring to  FIG. 8 , a timing controller  120  may comprise a luminance compensation unit  210  and a backlight control unit  220 . The backlight control unit  220  may output first light source control signals YCTRL 1  to YCTRL 8  and second light source control signals BCTRL 1  to BCTRL 8  being provided to the backlight controller  155  shown in  FIG. 1  in response to an image signal RGB provided from an external device. The backlight control unit  220  may output a first luminance compensation signal YC and a second luminance compensation signal BC in response to the image signal RGB. The luminance compensation unit  210  may compensate the luminance of the image signal RGB in response to the first luminance compensation signal YC and the second luminance compensation signal BC, and may output a data signal DATA as the compensation result to a data driver  140  shown in  FIG. 1 . 
       FIG. 9  is a block diagram schematically illustrating the backlight control unit shown in  FIG. 8 . 
     Referring to  FIG. 9 , a backlight control unit  220  may include an image splitter  222 , an image analyzer  224 , and a backlight control signal generator  226 . The image splitter  222  may divide a frame of image signal RGB input from an external device into image groups RGBG1 to RGBG8 respectively corresponding to display blocks DBK1 to DBK8 shown in  FIG. 3 . 
     The image analyzer  224  may output a first frequency signal RH corresponding to the frequency of each gradation of a red color, a second frequency signal GH corresponding to the frequency of each gradation of a green color, and a third frequency signal BH corresponding to the frequency of each gradation of a blue color, where the red, green, and blue colors are included in each of the image groups RGBG1 to RGBG8 from the image splitter  222 . 
     The backlight control signal generator  226  may determine an image type of each of the image groups RGBG1 to RGBG8 based on the first frequency signal RH, the second frequency signal GH, and the third frequency signal BH, and may output first light source control signals YCTRL 1  to YCTRL 8  and second light source control signals BCTRL 1  to BCTRL 8  corresponding to the determined image type. The backlight control signal generator  226  may output a first luminance compensation signal YC and a second luminance compensation signal BC corresponding to the determined image type. 
       FIG. 10  is a diagram showing a frame of image signal provided to an image splitter shown in  FIG. 9 , according to an exemplary embodiment of the present invention.  FIG. 11  is a diagram showing an image corresponding to a preselected display block in the display panel  110  shown in  FIG. 3 , from the image shown in  FIG. 10 .  FIGS. 12(A) and 12(B)  are diagrams showing a histogram analysis result of an image analyzer shown in  FIG. 9  on an image corresponding to the preselected display block shown in  FIG. 11 . 
     Referring to  FIGS. 9, 10, 11, 12 (A), and  12 (B), an image signal RGB, including a sky expressed by a blue color and a sun flower expressed by a yellow color, may be provided to the image splitter  222 . The image splitter  222  may divide a frame of image signal RGB into image groups RGBG1 to RGBG8 respectively corresponding to display blocks DBK1 to DBK8 of the display panel  110  shown in  FIG. 3 . For example, the histograms shown in  FIGS. 12(A) and 12(B)  may be calculated when the image analyzer  224  performs histogram analysis on an image group RGBG5, corresponding to a display block DBK5, from among an image signal RGB shown in  FIG. 10 . As illustrated in  FIGS. 12(A) and 12(B) , a frequency of occurrence of a red color of the image group RGBG5, including the sun flower, may be greater than that of a green color thereof. In this case, the display quality of an image displayed on the display panel  110  may be improved by making a turn-on time period of a first light source  151  (refer to  FIG. 6 ) for providing a yellow light become longer than that of a second light source  152  (refer to  FIG. 6 ) for providing a blue light. 
     The backlight control unit  220  shown in  FIG. 8  may improve the display quality of an image by setting pulse widths of first light source control signals YCTRL 1  to YCTRL 8  and second light source control signals BCTRL 1  to BCTRL 8  according to color characteristics of image groups RGBG1 to RGBG8. 
       FIGS. 13 to 16  are diagrams for describing a technique of setting pulse widths of first light source control signals and second light source control signals according to color characteristics of image groups. For ease of description, various exemplary embodiments will be described based on a first light control signal YCTRL 1  and a second light control signal BCTRL 1  that are generated from a backlight control unit  220  shown in  FIG. 8  and correspond to a light source block LBK1. Likewise, a backlight control unit  220  may generate first light source control signals YCTRL 2  to YCTRL 8  and second light source control signals BCTRL 2  to BCTRL 8  in the same manner. Referring to  FIGS. 13 to 16 , the backlight control unit  220  may have first to fourth modes. 
     Referring to  FIGS. 9 and 13 , the backlight control signal generator  226  of the backlight control unit  220  may determine an image type of each of image groups RGBG1 to RGBG8 in response to a first frequency signal RH, a second frequency signal GH, and a third frequency signal BH from the image analyzer  224 . 
     The following Table 1 shows a case where the backlight control unit  220  operates in the first mode. In the following tables 1, 2, 3, and 4, ‘R’ may indicate a red color, ‘G’ may indicate a green color, ‘B’ may indicate a blue color, ‘Y’ may indicate a yellow color, and ‘CBU’ may indicate color breakup. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Field 
                   
                   
                   
               
               
                 Type 
                 Split 
                 Decrease 
                 Increase 
                 Objects 
               
               
                   
               
             
            
               
                 SDD2 
                 No 
                 YCTRL 
                 BCTRL 
                 B color sense reinforcement 
               
               
                 SDD3 
                 No 
                 YCTRL 
                 YCTRL, 
                 B color sense reinforcement 
               
               
                   
                   
                   
                 BCTRL 
               
               
                 SDD4 
                 No 
                 YCTRL 
                 No 
                 Power consumption reduction 
               
               
                   
                   
                   
                   
                 color mixing improvement 
               
               
                 SDD5 
                 No 
                 BCTRL 
                 YCTRL 
                 R/G improvement 
               
               
                 SDD8 
                 No 
                 BCTRL 
                 No 
                 Power consumption reduction 
               
               
                   
                   
                   
                   
                 color mixing improvement 
               
               
                 SDD12 
                 No 
                 YCTRL, 
                 No 
                 Power consumption reduction 
               
               
                   
                   
                 BCTRL 
                   
                 color mixing improvement 
               
               
                 SDD13 
                 No 
                 No 
                 YCTRL 
                 R/G/Y color sense 
               
               
                   
                   
                   
                   
                 reinforcement 
               
               
                 SDD14 
                 No 
                 No 
                 BCTRL 
                 B color sense reinforcement 
               
               
                 SDD15 
                 No 
                 No 
                 YCTRL, 
                 R/G/Y/B color sense 
               
               
                   
                   
                   
                 BCTRL 
                 reinforcement 
               
               
                 Default 
                 No 
                 No 
                 No 
                 Default driving 
               
               
                   
               
            
           
         
       
     
     When an image type of the image group RGBG1 is one of SDD2 to SDD15, the backlight control signal generator  226  may output a first mode of first light control signal YCTRL 1  and second light control signal BCTRL 1  shown in  FIG. 13 . During the first mode, the first light control signal YCTRL 1  generated by the backlight control signal generator  226  may be activated within a portion of a period of a first sub frame SF1, and the second light control signal BCTRL 1  may be activated within a portion of a period of a second sub frame SF2. 
     During an active period ty11 of the first light control signal YCTRL 1 , a first light source voltage YVDD1 may be supplied to a first light source string YS shown in  FIG. 6 . During an active period tb12 of the second light control signal BCTRL 1 , a second light source voltage BVDD1 may be supplied to a second light source string BS shown in  FIG. 6 . That is, the active period ty11 of the first light control signal YCTRL 1  may be a turn-on time period of the first light source string YS, and the active period tb12 of the second light control signal BCTRL 1  may be a turn-on time period of the second light source string BS. Each of the active period ty11 of the first light control signal YCTRL 1  and the active period tb12 of the second light control signal BCTRL 1  may be determined according to an image type of the image group RGBG1. 
     For example, in the event that an image type of the image group RGBG1 is determined to be ‘SDD5’ through the backlight control signal generator  226 , the active period tb12 of the second light control signal BCTRL 1  may decrease, and the active period ty11 of the first light control signal YCTRL 1  may increase. The active period tb12 of the second light control signal BCTRL 1  and the active period ty11 of the first light control signal YCTRL 1  may increase or decrease from an initial setup time of a default state. An increment or decrement of the active period tb12 of the second light control signal BCTRL 1  and the active period ty11 of the first light control signal YCTRL 1  may be optimally determined at a test level of a fabricating process of a display device  100 . 
     The following Table 2 shows a case where the backlight control unit  220  operates in the second mode. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Type 
                 Field Split 
                 Decrease 
                 Increase 
                 Objects 
               
               
                   
               
             
            
               
                 SDD18 
                 YCTRL, 
                 YCTRL 
                 BCTRL 
                 CBU improvement 
               
               
                   
                 BCTRL 
                   
                   
                 B color sense reinforcement 
               
               
                 SDD20 
                 YCTRL, 
                 YCTRL 
                 No 
                 CBU improvement 
               
               
                   
                 BCTRL 
                   
                   
                 power consumption reduction 
               
               
                 SDD21 
                 YCTRL, 
                 BCTRL 
                 YCTRL 
                 CBU improvement 
               
               
                   
                 BCTRL 
                   
                   
                 R/G improvement 
               
               
                 SDD24 
                 YCTRL, 
                 BCTRL 
                 No 
                 CBU improvement 
               
               
                   
                 BCTRL 
                   
                   
                 power consumption reduction 
               
               
                 SDD28 
                 YCTRL, 
                 BCTRL 
                 No 
                 CBU improvement 
               
               
                   
                 BCTRL 
                   
                   
                 power consumption reduction 
               
               
                 SDD29 
                 YCTRL, 
                 No 
                 YCTRL 
                 CBU improvement 
               
               
                   
                 BCTRL 
                   
                   
                 R/G improvement 
               
               
                 SDD32 
                 YCTRL, 
                 No 
                 No 
                 CBU improvement 
               
               
                   
                 BCTRL 
               
               
                   
               
            
           
         
       
     
     Referring to  FIG. 14  and Table 2, when an image type of the image group RGBG1 is one of SDD18 to SDD32, the backlight control signal generator  226  may output a second mode of first light control signal YCTRL 1  and second light control signal BCTRL 1  shown in  FIG. 13 . During the second mode, the first light control signal YCTRL 1  generated by the backlight control signal generator  226  may be activated within a part of a period of the first sub frame SF1 and within a part of a period of the second sub frame SF2, and the second light control signal BCTRL 1  may be activated within a part of a period of the first sub frame SF1 and within a part of a period of a second sub frame SF2. The second mode may be a filed split mode where the first light control signal YCTRL 1  and the second light control signal BCTRL 1  are divided and activated into the first sub frame SF1 and the second sub frame SF2. 
     During the second mode, the backlight control signal generator  226  may change widths of active periods ty11 and ty12 of the first light control signal YCTRL 1  and widths of active periods tb11 and tb12 of the second light control signal BCTRL 1 , respectively. For example, in the event that the backlight control signal generator  226  shown in  FIG. 9  determines an image type of the image group RGBG1 as SDD20, it may decrease the active period tb12 of the first light control signal YCTRL 1 , and may maintain the active period tb11 of the second light control signal BCTRL 1  with the initial setup time. 
     A color breakup phenomenon may be reduced by increasing or decreasing the active period ty11 of the first light control signal YCTRL 1  and the active period tb12 of the second light control signal BCTRL 1  according to a color characteristic of an image signal RGB. 
     The following Table 3 shows a case where the backlight control unit  220  operates at the third mode. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                   
                 Field 
                   
                   
                   
               
               
                 Type 
                 Split 
                 Decrease 
                 Increase 
                 Objects 
               
               
                   
               
             
            
               
                 SDD34 
                 YCTRL 
                 YCTRL 
                 BCTRL 
                 CBU improvement 
               
               
                 SDD36 
                 YCTRL 
                 YCTRL 
                 No 
                 CBU improvement 
               
               
                   
                   
                   
                   
                 power consumption reduction 
               
               
                 SDD37 
                 YCTRL 
                 BCTRL 
                 YCTRL 
                 CBU improvement 
               
               
                   
                   
                   
                   
                 R/G/Y color sense 
               
               
                   
                   
                   
                   
                 improvement 
               
               
                 SDD40 
                 YCTRL 
                 BCTRL 
                 No 
                 CBU improvement 
               
               
                   
                   
                   
                   
                 power consumption reduction 
               
               
                 SDD44 
                 YCTRL 
                 YCTRL, 
                 No 
                 CBU improvement 
               
               
                   
                   
                 BCTRL 
                   
                 power consumption reduction 
               
               
                 SDD45 
                 YCTRL 
                 No 
                 YCTRL 
                 CBU improvement 
               
               
                   
                   
                   
                   
                 R/G Desaturation 
               
               
                   
                   
                   
                   
                 improvement 
               
               
                 SDD46 
                 YCTRL 
                 No 
                 BCTRL 
                 CBU improvement 
               
               
                   
                   
                   
                   
                 B color sense improvement 
               
               
                 SDD47 
                 YCTRL 
                 No 
                 YCTRL, 
                 CBU improvement 
               
               
                   
                   
                   
                 BCTRL 
                 R/G/Y/B color sense 
               
               
                   
                   
                   
                   
                 improvement 
               
               
                 SDD48 
                 YCTRL 
                 No 
                 No 
                 CBU improvement 
               
               
                   
               
            
           
         
       
     
     Referring to  FIG. 15  and Table 3, when an image type of the image group RGBG1 is one of SDD34 to SDD48, the backlight control signal generator  226  may output a third mode of first light control signal YCTRL 1  and second light control signal BCTRL 1 . During the third mode, the first light control signal YCTRL 1  generated by the backlight control signal generator  226  may be activated within a portion of a period of the first sub frame SF1 and within a portion of a period of the second sub frame SF2, and the second light control signal BCTRL 1  may be activated within a portion of a period of a second sub frame SF2. The third mode may be a filed split mode where the first light control signal YCTRL 1  is divided and activated into the first sub frame SF1 and the second sub frame SF2. 
     During the third mode, the backlight control signal generator  226  may change the widths of active periods ty11 and ty12 of the first light control signal YCTRL 1  and a width of an active period tb12 of the second light control signal BCTRL 1 , respectively. For example, in the event that the backlight control signal generator  226  shown in  FIG. 9  determines an image type of the image group RGBG1 as SDD47, it may increase the widths of the active periods ty11 and ty12 of the first light control signal YCTRL 1  and a width of the active period tb12 of the second light control signal BCTRL 1 . 
     The following table 3 shows a case where the backlight control unit  220  operates in the fourth mode. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 4 
               
               
                   
               
               
                   
                 Field 
                   
                   
                   
               
               
                 Type 
                 Split 
                 Reduction 
                 Decrease 
                 Increase 
               
               
                   
               
             
            
               
                 SDD50 
                 BCTRL 
                 YCTRL 
                 BCTRL 
                 CBU improvement 
               
               
                   
                   
                   
                   
                 Blue color sense improvement 
               
               
                 SDD52 
                 BCTRL 
                 YCTRL 
                 No 
                 CBU improvement 
               
               
                   
                   
                   
                   
                 power consumption reduction 
               
               
                 SDD53 
                 BCTRL 
                 BCTRL 
                 YCTRL 
                 CBU improvement 
               
               
                   
                   
                   
                   
                 R/G/Y color sense 
               
               
                   
                   
                   
                   
                 improvement 
               
               
                 SDD56 
                 BCTRL 
                 BCTRL 
                 No 
                 CBU improvement 
               
               
                   
                   
                   
                   
                 power consumption reduction 
               
               
                 SDD60 
                 BCTRL 
                 YCTRL, 
                 No 
                 CBU improvement 
               
               
                   
                   
                 BCTRL 
                   
                 power consumption reduction 
               
               
                 SDD61 
                 BCTRL 
                 No 
                 YCTRL 
                 CBU improvement 
               
               
                   
                   
                   
                   
                 R/G/Y color sense 
               
               
                   
                   
                   
                   
                 improvement 
               
               
                 SDD62 
                 BCTRL 
                 No 
                 BCTRL 
                 CBU improvement 
               
               
                   
                   
                   
                   
                 B color sense improvement 
               
               
                 SDD63 
                 BCTRL 
                 No 
                 YCTRL, 
                 CBU improvement 
               
               
                   
                   
                   
                 BCTRL 
                 R/G/B/Y color sense 
               
               
                   
                   
                   
                   
                 improvement 
               
               
                 SDD64 
                 BCTRL 
                 No 
                 No 
                 CBU improvement 
               
               
                   
               
            
           
         
       
     
     Referring to  FIG. 16  and Table 4, when an image type of the image group RGBG1 is one of SDD50 to SDD64, the backlight control signal generator  226  may output a fourth mode of first light control signal YCTRL 1  and second light control signal BCTRL 1 . During the fourth mode, the first light control signal YCTRL 1  generated by the backlight control signal generator  226  may be activated within a portion of a period of the first sub frame SF1, and the second light control signal BCTRL 1  may be activated within a portion of a period of the first sub frame SF1 and within a portion of a period of a second sub frame SF2. The fourth mode may be a filed split mode where the second light control signal BCTRL 1  is divided and activated into the first sub frame SF1 and the second sub frame SF2. 
     During the fourth mode, the backlight control signal generator  226  may change a width of the active period ty11 of the first light control signal YCTRL 1  and the widths of the active periods tb11 and tb12 of the second light control signal BCTRL 1 , respectively. For example, in the event that the backlight control signal generator  226  shown in  FIG. 9  determines an image type of the image group RGBG1 as SDD62, it may maintain the active period ty12 of the first light control signal YCTRL 1  with an initial setup time, and may increase the widths of the active periods tb11 and tb12 of the second light control signal BCTRL 1 . 
       FIGS. 17 to 21  are diagrams schematically illustrating a crystal transmittance ratio that is varied when pulse widths of first and second light control signals are varied. 
     Referring to  FIG. 17 , a frame of image signal RGB provided from an external device may include a sky expressed by a blue color, a field expressed by a green color, and a letter ‘Display’ expressed by a yellow color. A variation in a color transmittance ratio of a preselected pixel A of a display block DBK1 when the display panel  110  is divided into eight display blocks DBK1 to DBK8 is illustrated in  FIG. 18 . A variation in a color transmittance ratio of a preselected pixel B of a display block DBK5 when the display panel  110  is divided into the eight display blocks DBK1 to DBK8 is illustrated in  FIG. 19 . A variation in a color transmittance ratio of a preselected pixel C of a display block DBK8 when the display panel  110  is divided into the eight display blocks DBK1 to DBK8 is illustrated in  FIG. 20 . A variation in a color transmittance ratio of a preselected pixel D of the display block DBK8 when the display panel  110  is divided into the eight display blocks DBK1 to DBK8 is illustrated in  FIG. 21 . 
     Referring to  FIGS. 18 to 21 , an active period ty11 of a first light control signal YCTRL 1  and an active period tb12 of a second light control signal BCTRL 1  may be constant when a backlight control signal generator  226  (refer to  FIG. 9 ) operates in a first mode included in Table 1, at a default state. 
     As illustrated in  FIGS. 17 and 18 , because the display block DBK1 expresses a sky having a blue color, a red color, and a green color, an image group RGBG1 may be less than a blue color. The backlight control signal generator  226  may then determine an image type of the image group RGBG1 as ‘SDD4’ of the first mode in response to a first frequency signal RH, a second frequency signal GH, and a third frequency signal BH from an image analyzer  224 . 
     The first light control signal YCTRL 1  generated by the backlight control signal generator  226  may be activated within a portion of a period corresponding to a first sub frame SF1, and the second light control signal BCTRL 1  may be activated within a portion of a period corresponding to a second sub frame SF2. The backlight control signal generator  226  may reduce the power consumed by a backlight unit  150  by making the active period ty11 of the first light control signal YCTRL 1  become shorter than that of the default state. The backlight control signal generator  226  may output a first luminance compensation signal YC and a second luminance compensation signal BC corresponding to the image type of ‘SDD4’ thus determined. In exemplary embodiments, the backlight control signal generator  226  may output the first luminance compensation signal YC and the second luminance compensation signal BC to compensate for the active period ty11 of the first light control signal YCTRL 1  thus shortened. In response to the first luminance compensation signal YC and the second luminance compensation signal BC from the backlight control unit  220 , the luminance compensation unit  210  may output a data signal DATA such that luminance becomes brighter at the first sub frame SF1 and the second sub frame SF2. For example, if the active period ty11 of the first light control signal YCTRL 1  is shorter than that of the default state, that is, if a gradation value of the data signal DATA in the first sub frame SF1 being provided to a crystal capacitor CLC (refer to  FIG. 1 ) is set to a maximum value, a blue color of the second sub frame SF2 may be brighter. 
     As illustrated in  FIGS. 17 and 19 , a white of the display block BLK5 may be more than that of the display block DBK1. The backlight control signal generator  226  may determine an image type of the image group RGBG1 as ‘SDD56’ of the fourth mode in response to the first frequency signal RH, the second frequency signal GH, and the third frequency signal BH from the image analyzer  224 . 
     The first light control signal YCTRL 1  generated by the backlight control signal generator  226  may be activated within a portion of a period corresponding to the first sub frame SF1, and the second light control signal BCTRL 1  may be activated within a portion of a period corresponding to the first sub frame SF1 and within a portion of a period corresponding to the second sub frame SF2. As the second light control signal BCTRL 1  is activated with respect to the first sub frame SF1 and the second sub frame SF2, under the control of the backlight control signal generator  226 , such that active periods tb11 and tb12 of the second light control signal BCTRL 1  are shorter than those of the default state, a color breakup phenomenon may be minimized such that a color of the first sub frame SF1 and a color of the second sub frame SF2 are seen independently. 
     Referring to  FIGS. 17 and 20 , green and yellow colors of the display block DBLK8 may be more intense than a blue color thereof. The backlight control signal generator  226  may determine an image type of the image group RGBG1 as ‘SDD5’ of the first mode in response to the first frequency signal RH, the second frequency signal GH, and the third frequency signal BH from the image analyzer  224 . 
     The first light control signal YCTRL 1  generated by the backlight control signal generator  226  may be activated within a portion of a period corresponding to the first sub frame SF1, and the second light control signal BCTRL 1  may be activated within a portion of a period corresponding to the second sub frame SF2. The backlight control signal generator  226  may improve a red color and a green color by making the active period ty11 of the first light control signal YCTRL 1  become longer than that of the default state, and the active period tb11 of the second light control signal BCTRL 1  become shorter than that of the default state. The backlight control signal generator  226  may output the first luminance compensation signal YC and the second luminance compensation signal BC to compensate for the shortened active period tb11 of the second light control signal BCTRL 1 . In response to the first luminance compensation signal YC and the second luminance compensation signal BC from the backlight control unit  220 , the luminance compensation unit  210  may output the data signal DATA such that luminance of the pixel C becomes brighter. 
     As in  FIG. 20 , the first light control signal YCTRL 1  shown in  FIG. 21  may be activated within a portion of a period corresponding to the first sub frame SF1, and the second light control signal BCTRL 1  within a portion of a period corresponding to the second sub frame SF2. The backlight control signal generator  226  may make the active period ty11 of the first light control signal YCTRL 1  become longer than that of the default state, and the active period tb11 of the second light control signal BCTRL 1  become shorter than that of the default state. Thus, the backlight control signal generator  226  may minimize a phenomenon in which a yellow color of a letter ‘Display’ is mixed with a blue color at the second sub frame SF2. 
       FIG. 22  is a diagram schematically illustrating the image signal of  FIG. 10  displayed on the display panel  110 , when the timing controller  120  shown in  FIG. 1  operates in a default state of a first mode.  FIG. 23  is a diagram schematically illustrating the image signal of  FIG. 10  displayed on the display panel  110 , when the timing controller  120  shown in  FIG. 1  operates according to an image type of an image signal. 
       FIG. 24  is a diagram schematically illustrating a mixing ratio of a yellow color and a blue color of an image displayed on the display panel  110  shown in  FIGS. 22 and 23  according to an operation state of the timing controller  120  shown in  FIG. 1 . A horizontal axis of a graph shown in  FIG. 24  may indicate a second-direction (X2) distance (or, a vertical distance) from a top of the display panel  110 , and a vertical axis may indicate a color mixing ratio. 
     Referring to  FIGS. 22 and 24 , when the timing controller  120  operates in a default state of a first mode shown in Table 1, first light source control signals YCTRL 1  to YCTRL 8  and second light source control signals BCTRL 1  to BCTRL 8  may have active periods ty11 to ty81 and tb12 to tb82, each having a set pulse width (refer to  FIG. 7 ). Therefore, a mixing ratio of a yellow color and a blue color of an image displayed on the display panel  110  may have a constant pattern over the display panel  110 . 
     Referring to  FIGS. 23 and 24 , when operating according to an image type SDDk of image signal, the timing controller  120  may operate in one of first to fourth modes described above, and the first light source control signals YCTRL 1  to YCTRL 8  and the second light source control signals BCTRL 1  to BCTRL 8  may have one of the patterns shown in  FIGS. 13 to 16 . 
     As illustrated in  FIG. 23 , a blue color of sky may be expressed at a top of the display panel  110 , and a yellow color of sun flowers may be expressed toward a bottom of the display panel  110 , such that an amount of blue color toward the bottom of the display panel  110  may be less than red and green colors. Therefore, under the control of the timing controller  120 , the display panel  110  may be driven by a ‘SDD12’ type of the first mode from a display block DBK5 of the display panel  110 . In this case, as illustrated in  FIG. 13 , the first light source control signals YCTRL 1  to YCTRL 8  may be activated within a first sub frame SF1, and the second light source control signals BCTRL 1  to BCTRL 8  may be activated within a second sub frame SF2. Thus, active periods ty11 to ty18 of the first light source control signals YCTRL 1  to YCTRL 8  and active periods tb12 to tb82 of the second light source control signals BCTRL 1  to BCTRL 8  are reduced as compared with a default state. If the active periods ty11 to ty18 of the first light source control signals YCTRL 1  to YCTRL 8 , and the active periods tb12 to tb82 of the second light source control signals BCTRL 1  to BCTRL 8  are reduced in duration, turn-on time periods of first and second light sources  151  and  156  may be decreased. This may mean that power consumption of a ‘SDD12’ type is reduced by about 14% as compared with the default state. As illustrated in  FIG. 24 , there may be remarkably reduced a color mixing phenomenon of a blue color at the bottom of the display panel  110  where sun flowers are expressed. 
       FIG. 25  is a diagram schematically illustrating turn-on time periods of first and second light sources when an image illustrated in  FIGS. 22 and 23  is displayed on a display pane according to an operation state of the timing controller  120  shown in  FIG. 1 . In  FIG. 25 , a horizontal axis may indicate light source blocks LBKi (i=1, 2, . . . , 8), and a vertical axis may indicate turn-on time periods of first and second light sources  151  and  152  (refer to  FIG. 6 ). 
     Referring to  FIGS. 22 and 25 , when the timing controller  120  operates in a default state of a first mode shown in Table 1, first light source control signals YCTRL 1  to YCTRL 8  and second light source control signals BCTRL 1  to BCTRL 8  may have active periods ty11 to ty81 and tb12 to tb82, each having a preset pulse width (refer to  FIG. 7 ). Therefore, turn-on time periods of first and second light sources  151  and  152  in light source blocks LB1 to LBK8 may be constantly maintained. 
     Referring to  FIGS. 23 and 25 , when operating according to an image type SDDk of image signal, the timing controller  120  may operate in one of first to fourth modes described above, and the first light source control signals YCTRL 1  to YCTRL 8  and the second light source control signals BCTRL 1  to BCTRL 8  may have one of patterns shown in  FIGS. 13 to 16 . For example, in the event that the display panel  110  is driven by a ‘SDD12’ type of the first mode from a display block DBK5 of the display panel  110  under the control of the timing controller  120 , there may be a remarkably reduced turn-on time period of a second light source  152  providing a blue color light. 
       FIG. 26  is a diagram schematically illustrating an image signal (including a red color and a yellow color) displayed on the display panel  110  when the timing controller  120  shown in  FIG. 1  operates in a default state of a first mode.  FIG. 27  is a diagram schematically illustrating an image signal (including a red color and a yellow color) displayed on the display panel  110  when the timing controller  120  shown in  FIG. 1  operates according to an image type of an image signal. 
       FIG. 28  is a diagram schematically illustrating a mixing ratio of a yellow color and a blue color of an image displayed on the display panel  110  shown in  FIGS. 26 and 27  according to an operation state of the timing controller  120  shown in  FIG. 1 . A horizontal axis of a graph shown in  FIG. 28  may indicate a second-direction (X2) distance (or, a vertical distance) from a top of the display panel  110 , and a vertical axis may indicate a color mixing ratio. 
     Referring to  FIGS. 26 and 28 , when the timing controller  120  operates in a default state of a first mode shown in the table 1, first light source control signals YCTRL 1  to YCTRL 8  and second light source control signals BCTRL 1  to BCTRL 8  may have active periods ty11 to ty81 and tb12 to tb82, each having a preset pulse width (refer to  FIG. 7 ). Therefore, a mixing ratio of a yellow color and a blue color of an image displayed on the display panel  110  may have a constant pattern over the display panel  110 . 
     Referring to  FIGS. 27 and 28 , when operating according to an image type SDDk of image signal, the timing controller  120  may operate in one of first to fourth modes described above, and the first light source control signals YCTRL 1  to YCTRL 8  and the second light source control signals BCTRL 1  to BCTRL 8  may have one of the patterns shown in  FIGS. 13 to 16 . 
     As illustrated in  FIG. 27 , an image expressed over the display panel  110  may include a wallpaper of a red color and a character ‘M’ expressed by a yellow color. That is, because an image expressed on the display panel  110  does not include a blue color, display blocks DBK1 to DBK8 DBK1 of the display panel  110  all may be driven by a ‘SDD8’ type of the first mode under the control of the timing controller  120 . If the active periods tb12 to tb82 of the second light source control signals BCTRL 1  to BCTRL 8  are reduced in duration, a turn-on time period of the second light sources  152  is also reduced (refer to  FIG. 6 ). Thus, power consumption of a ‘SDD8’ type may be reduced by about 40% as compared with the default state. As illustrated in  FIG. 26 , there may be a remarkably reduced color mixing phenomenon of a blue color is mixed with a red color and a yellow color. 
       FIG. 29  is a diagram schematically illustrating turn-on time periods of first and second light sources  151 ,  152  when an image illustrated in  FIGS. 26 and 27  is displayed on a display pane according to an operation state of the timing controller  120  shown in  FIG. 1 . In  FIG. 29 , a horizontal axis may indicate light source blocks LBKi (i=1, 2, . . . , 8), and a vertical axis may indicate turn-on time periods of first and second light sources  151  and  152  (refer to  FIG. 6 ). 
     Referring to  FIGS. 26 and 29 , when the timing controller  120  operates in a default state of a first mode shown in Table 1, first light source control signals YCTRL 1  to YCTRL 8  and second light source control signals BCTRL 1  to BCTRL 8  may have active periods ty11 to ty81 and tb12 to tb82, each having a preset pulse width (refer to  FIG. 7 ). Therefore, turn-on time periods of first and second light sources  151  and  152  in light source blocks LB1 to LBK8 may be constantly maintained. 
     Referring to  FIGS. 27 and 29 , when operating according to an image type SDDk of image signal, the timing controller  120  may operate in one of first to fourth modes described above, and the first light source control signals YCTRL 1  to YCTRL 8  and the second light source control signals BCTRL 1  to BCTRL 8  may have one of the patterns shown in  FIGS. 13 to 16 . For example, in the event that display blocks DBK1 to DBK8 DBK1 to DBK8 of the display panel  110  all are driven by a ‘SDD8’ type under the control of the timing controller  120 , there may be a remarkably reduced turn-on time of a second light source  152  providing a blue color light. 
       FIG. 30  is a block diagram schematically illustrating a display device according to an exemplary embodiment of the present invention. In  FIG. 30 , constituent elements that are the same as those in  FIG. 1  may be represented by the same reference numerals, and a description thereof is thus omitted. 
     Referring to  FIG. 30 , a display device may comprise the display panel  110 , the timing controller  120 , a gate driver  130 , the data driver  140 , and a backlight unit  160 . The timing controller  120 , the gate driver  130 , and the data driver  140  may constitute a display panel driving unit that drives the display panel  110 . 
     The backlight unit  150  shown in  FIG. 1  may be a direct type of backlight that is disposed at the rear of the display panel  110  and supplies a light to the display panel  110 . The backlight unit  150  shown in  FIG. 3  may be an edge type of backlight that is disposed at one edge of the display panel  110  and supplies a light to the display panel  110 . The backlight unit  160  may be disposed to be adjacent to one of a long edge and a short edge of the display panel  110 . Alternatively, the backlight unit  160  may be respectively disposed at two long edges of the display panel  110  with the display panel  110  interposed therebetween, or may be respectively disposed at two short edges of the display panel  110  with the display panel  110  interposed therebetween. 
       FIG. 31  is a diagram schematically illustrating an arrangement of light sources of the backlight unit  160  shown in  FIG. 30 . 
     Referring to  FIG. 31 , a backlight unit  160  may include light source blocks LBK11 to LBK18 LBK11 to LBK18 respectively corresponding to display blocks DBK1 to DBK8 (refer to  FIG. 3 ) of the display panel  110 . Each of the light source blocks LBK11 to LBK18 may include the first light sources  151  and the second light sources  152 . As described with reference to  FIG. 2 , the first light sources  151  may provide a first color light, and the second light sources  152  may provide a second color light. The first light sources  151  and the second light sources  152  may be sequentially and alternately disposed along a second direction X2.  FIG. 31  illustrates an exemplary embodiment in which the first light sources  151  and the second light sources  152  are arranged in line. However, the present invention is not limited thereto. For example, the first light sources  151  and the second light sources  152  may be arranged in two or more lines. 
       FIG. 32  is a block diagram schematically illustrating the backlight unit  160  shown in  FIG. 30 . 
     Referring to  FIG. 32 , a backlight unit  160  may include the backlight controller  165  and light source blocks LBK11 to LBK18. The backlight controller  165  may receive first light source control signals YCTRL 1  to YCTRL 8  and second light source control signals BCTRL 1  to BCTRL 8  from the timing controller  120  shown in  FIG. 1  to generate first light source voltages YVDD1 to YVDD8 and second light source voltages BVDD1 to BVDD8 that supply power to light source blocks LBK11 to LBK18. 
     Each of the light source blocks LBK11 to LBK18 may include a first light source string YS1 including first light sources  151  connected in series and a second light source string BS1 including second light sources  152  connected in series. 
     First light source strings YS1 in the light source blocks LBK11 to LBK18 may be supplied with first light source voltages YVDD1 to YVDD8 from the backlight controller  165 , and second light source strings BS1 in the light source blocks LBK11 to LBK18 may be supplied with second light source voltage BVDD1 to BVDD8 from the backlight controller  165 . 
     The timing controller  120  shown in  FIG. 30  may generate the first light source control signals YCTRL 1  to YCTRL 8  and the second light source control signals BCTRL 1  to BCTRL 8  according to the same scheme as described with reference to Tables 1 to 4 and timing diagrams shown in  FIGS. 6 and 13 to 16 , and may provide them to the backlight controller  165 . 
       FIG. 33  is a flow chart for describing a driving method of a display device according to an exemplary embodiment of the present invention. For ease of description, a driving method of a display device will be described with reference to the display device  100  shown in  FIG. 1  and a timing controller  120  shown in  FIG. 8 . 
     In step S 440 , referring to  FIGS. 8 and 33 , the timing controller  120  may receive an image signal RGB. 
     In step S 410 , a backlight control unit  220  may determine pulse widths of first light source control signals YCLTRL 1  to YCTRL 8  and second light source control signals BCTRL 1  to BCTRL 8  according to a color characteristic of an image signal RGG. In step S 420 , a backlight unit  150  (refer to  FIG. 1 ) may provide a first color light and a second color light during times respectively corresponding to the first light source control signals YCLTRL 1  to YCTRL 8  and the second light source control signals BCTRL 1  to BCTRL 8 . 
       FIG. 34  is a flow chart for describing a method of deciding a pulse width of each of first light source control signals and second light source control signals shown in  FIG. 33 . For ease of description, a driving method of a display device will be described with reference to the display device  100  shown in  FIG. 1  and the timing controller  120  shown in  FIG. 8 . 
     Referring to  FIGS. 9 and 34 , to determine a pulse width of each of first light source control signals and second light source control signals, in step S 411 , an image splitter  222  may divide an image signal RGB into image groups RGBG1 to RGBG8 respectively corresponding to display blocks DBK1 to DKB8 (refer to  FIG. 3 ). 
     In step S 412 , the image analyzer  224  may analyze color characteristics of the image groups RGBG1 to RGBG8 to output first to third frequency signals RH, GH, and BH. After sequentially analyzing color characteristics of the image groups RGBG1 to RGBG8, the image analyzer  224  may output the first to third frequency signals RH, GH, and BH corresponding to a color characteristic of the image group RGBG1, and may output the first to third frequency signals RH, GH, and BH corresponding to a color characteristic of the image group RGBG2. First to third frequency signals RH, GH, and BH corresponding to a color characteristic of each of the image groups RGBG1 to RGBG8 may be generated in the same manner as described above. 
     In step S 413 , a backlight control signal generator  226  may determine an image type of each of the image groups RGBG1 to RGBG8 based on the first to third frequency signals RH, GH, and BH. In step S 414 , the backlight control signal generator  226  may set a pulse width of each of first light source control signals YCLTRL 1  to YCTRL 8  and the second light source control signals BCTRL 1  to BCTRL 8  to a pulse width corresponding to the determined image type. 
     The backlight control signal generator  226  may output a first luminance compensation signal YC and a second luminance compensation signal BC corresponding to the decoded image type. A luminance compensation unit  210  (refer to  FIG. 8 ) may output a data signal DATA obtained by compensating for luminance of the image signal RGB in response to the first luminance compensation signal YC and the second luminance compensation signal BC. 
     The exemplary embodiments of the present invention make it possible to realize full color on a display panel using a time/space division scheme. Also, the exemplary embodiments of the present invention permit adjustment of turn-on times of first and second light sources of a backlight unit according to a color characteristic of an image being displayed. In particular, the display panel may be divided into a plurality of display blocks, and the backlight unit may be divided into a plurality of light source blocks to correspond to the plurality of display blocks. The turn-on times of the first and second light sources in a light source block may be adjusted according to a color characteristic of an image being displayed within each display block. Thus, the quality of an image being displayed on a display panel may be improved. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.