Patent Publication Number: US-2023147349-A1

Title: Display device with frame frequency synchronization

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2021-0152175 filed on Nov. 08, 2021 in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to a display device. More particularly, the present disclosure relates to a display device with frame frequency synchronization. 
     DISCUSSION OF THE RELATED ART 
     Display devices are used to facilitate the transfer of information to users. For example, display devices have been employed in various electronic devices such as smartphones, digital cameras, laptop computers, navigation devices, and smart televisions. Recently, several types of flat panel display devices have been developed, such as liquid crystal display devices, field emission display devices, or organic light emitting display devices. A light emitting display device may display an image without a separate backlight unit providing light to a display panel, as each of the pixels of the display panel includes a light emitting element that may emit light by itself. 
     Some display devices may further include a touch driver for recognizing a touch input . The touch driver determines whether or not a user has touched the screen, and calculates a corresponding position as coordinates of the touch input. When a display unit (DU) and the touch driver are simultaneously driven, display noise may be generated due to a disturbance in a coupled signal of the display unit DU and the touch driver. 
     SUMMARY 
     Aspects of the disclosure provide a display device capable of recognizing a frame frequency by a touch driver when the frame frequency at which a display driver controls a display panel varies. 
     Aspects of the disclosure also provide a display device capable of minimizing an effect of noise on a touch driving signal originating from a display panel and of preventing unnecessary power consumption while maintaining performance of a touch panel, when a frame frequency varies. 
     However, aspects of the disclosure are not restricted to those set forth herein. The above and other aspects of the disclosure will become more apparent to one of ordinary skill in the art to which the disclosure pertains by referencing the detailed description of the disclosure given below. 
     According to an embodiment of the disclosure, a display device includes a display unit, a touch unit, a display driver configured to drive the display unit and including a synchronization signal generator, and a touch driver configured to drive the touch unit and including a synchronization signal receiver and a touch signal adjuster, wherein the synchronization signal generator is configured to generate a vertical synchronization signal supporting a frequency of a display signal applied to the display unit based on input frame frequency information and a horizontal synchronization signal supporting the frequency of the display signal and including the frame frequency information based on the frame frequency information and the vertical synchronization signal, and wherein the synchronization signal receiver is configured to receive the horizontal synchronization signal. 
     In an embodiment, the vertical synchronization signal may include a synchronization signal section having a first signal waveform and a porch section having a second signal waveform different from the first signal waveform, the horizontal synchronization signal includes a first section corresponding to the synchronization signal section and a second section corresponding to the porch section, and the first section includes the first signal waveform, and the second section includes a third signal waveform different from the first signal waveform and the second signal waveform, and includes the frame frequency information. 
     In an embodiment, the third signal waveform may reflect (e.g., include) the frame frequency information in the form of a duty value, wherein the duty value is mapped to the frequency of the display signal in a lookup table. 
     In an embodiment, the display driver may further include a memory storing a value of a first pulse width according to the frame frequency information, the memory may further store the lookup table, and the third signal waveform includes a first pulse that rises at the same time as the start of the porch section, is maintained by the first pulse width, and then falls. 
     In an embodiment, the first pulse width of the first pulse may be 4 to 100 times the width of a pulse width of a unit clock of a clock signal applied to the display driver. 
     In an embodiment, the synchronization signal generator may include a clock generator configured to receive a clock control signal, to generate the third signal waveform, and to output the clock signal corresponding to a frame frequency. 
     In an embodiment, the synchronization signal generator may include a clock generator configured to receive a voltage control signal, to generate the third signal waveform, and to output the voltage signal. 
     In an embodiment, the touch signal adjuster may be configured to receive the frame frequency information included in the horizontal synchronization signal from the synchronization signal receiver and to modulate a touch driving signal based on the frame frequency information. 
     In an embodiment, the touch driver further may include a voltage generator which varies an amplitude of the touch driving signal according to the frame frequency information. 
     In an embodiment, the modulated touch driving signal may include an effective touch driving section having a first amplitude and a noise touch driving section having a second amplitude different from the first amplitude. 
     In an embodiment, the synchronization signal receiver may be configured to further receive the vertical synchronization signal. 
     In an embodiment, the display unit and the touch unit may be provided in a single panel, and the display driver and the touch driver may be included in a driving chip connected to the single panel. 
     In an embodiment, the synchronization signal generator includes a first output terminal outputting the vertical synchronization signal and a second output terminal for outputting the second synchronization signal, the touch driver includes a first input terminal and a second input terminal, and a first synchronization signal information line connects the first output terminal to the first input terminal, a second synchronization signal information line connects the second output terminal to the second input terminal, and wherein the first synchronization signal information line and the second synchronization signal information line are each disposed between the synchronization signal generator and the touch driver. 
     According to another embodiment of the disclosure, a display device comprise a display unit, a touch unit disposed to overlap the display unit, a display driver configured to drive the display unit and including a synchronization signal generator, and a touch driver configured to drive the touch unit and including a synchronization signal receiver and a touch signal adjuster, wherein the synchronization signal generator is configured to generate a vertical synchronization signal supporting a frequency of a display signal applied to the display unit based on input frame frequency information and a horizontal synchronization signal supporting the frequency of the display signal and including the frame frequency information, wherein the horizontal synchronization signal is based on the frame frequency information and the vertical synchronization signal, and wherein the synchronization signal receiver is configured to receive the horizontal synchronization signal. 
     In an embodiment, the vertical synchronization signal may include a synchronization signal section having a first signal waveform and a porch section having a second signal waveform, the horizontal synchronization signal includes a first section corresponding to the synchronization signal section and a second section corresponding to the porch section, and the first section includes the first signal waveform, and the second section includes a third signal waveform different from the first signal waveform and the second signal waveform, and includes the frame frequency information in the form of a duty value, wherein the duty value is mapped to the frequency of the display signal in a lookup table. 
     In an embodiment, the third signal waveform may include a first pulse that rises at the same time as the start of the porch section, is maintained by a first pulse width, and then falls. 
     In an embodiment, the touch signal adjuster may be configured to receive the frame frequency information included in the horizontal synchronization signal from the synchronization signal receiver and to modulate a touch driving signal based on the frame frequency information. 
     In an embodiment, the modulated touch driving signal may include an effective touch driving section having a first amplitude and a noise touch driving section having a second amplitude different from the first amplitude. 
     In an embodiment, the synchronization signal receiver may be configured to further receive the vertical synchronization signal. 
     In an embodiment, the display unit and the touch unit may be provided in a single panel, and the display driver and the touch driver are included in a driving chip connected to the single panel. 
     With the display device according to an embodiment, even though a frame frequency at which the display driver controls a display panel varies, an influence of noise from the display signals on touch driving signals acting from the display panel may be minimized. 
     Further, in some embodiments, the touch driving signals applied to a touch panel are changed according to a change in the frame frequency of the display device, and thus, unnecessary power consumption may be prevented while maintaining performance of the touch panel. In addition, distortion of the touch driving signals due to data signals may be decreased, and distortion of an image quality may be minimized while maintaining reliability of touch sensitivity. 
     The effects of the disclosure are not limited to the aforementioned effects, and persons of ordinary skill in the art will recognize various other effects from the specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects and features of the disclosure will become more apparent by describing in detail embodiments thereof with reference to the attached drawings, in which: 
         FIG.  1    is a schematic plan view of a display device according to an embodiment; 
         FIG.  2    is a schematic cross-sectional view of the display device according to an embodiment; 
         FIG.  3    is a block diagram that illustrates a display unit and a touch driver according to an embodiment; 
         FIG.  4    is a schematic plan view that illustrates the display unit of the display device according to an embodiment; 
         FIG.  5    is a plan view that illustrates a touch unit of the display device according to an embodiment; 
         FIG.  6    is a detailed block diagram of a frame frequency synchronization signal controller according to an embodiment; 
         FIG.  7    is a detailed block diagram of the touch driver according to an embodiment; 
         FIG.  8    is a block diagram that illustrates a relationship between a display driver and the touch driver according to an embodiment; 
         FIGS.  9  and  10    are timing diagrams that illustrate a method of driving the display driver according to an embodiment; 
         FIGS.  11  and  12    are flowcharts for describing operations of the display device according to an embodiment; 
         FIG.  13    is a timing diagram that illustrates signals of the display device according to an embodiment; 
         FIGS.  14  and  15    are flowcharts that illustrate a method of driving the touch driver according to embodiments; 
         FIG.  16    is a timing diagram that illustrates a method of driving a display driver according to another embodiment; 
         FIG.  17    is a timing diagram that illustrates a method of driving a display driver according to still another embodiment; and 
         FIG.  18    is a block diagram that illustrates the display device according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Embodiments of the inventive concept will now be described more fully hereinafter with reference to the accompanying drawings. The present disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will filly convey the scope of the inventive concept to those skilled in the art. Throughout the specification, like reference symbols in the drawings may denote like elements, and to the extent that a description of an element has been omitted, it may be understood that the element is at least similar to corresponding elements that are described elsewhere in the specification. 
     It will be understood that when a layer is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. 
     It will be understood that, although the terms “first,” “second,” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For instance, a first element discussed below could be termed a second element without departing from the teachings of the present inventive concepts. Similarly, the second element could also be termed the first element. 
     Hereinafter, example embodiments will be described with reference to the accompanying drawings. 
       FIG.  1    is a schematic plan view of a display device according to an embodiment.  FIG.  2    is a schematic cross-sectional view of the display device according to an embodiment. 
     In the drawings, a first direction X is parallel to one side of a display device  10  in plan view, and refers to a short side direction of the display device  10 . A second direction Y is a direction parallel to the long side of the display device  10  in plan view, and refers to a long side direction of the display device  10 . A third direction Z refers to a thickness direction of the display device  10 . However, it should be understood that directions mentioned in embodiments refer to relative directions, and various embodiments and their orientations are not limited to the mentioned directions. 
     The display device  10  may be or be used in various electronic devices that provide display screens. For example, the display device  10  may be applied to portable electronic devices such as mobile phones, smartphones, tablet personal computers (PCs), mobile communication terminals, electronic notebooks, electronic books, portable multimedia players (PMPs), navigation devices, and ultra mobile PCs (UMPCs). For example, the display device  10  may be applied as a display unit DU of televisions, laptop computers, monitors, billboards, or the Internet of Things (IOTs). In addition, the display device  10  may be applied to wearable devices such as smart watches, watch phones, glasses-type displays, and head mounted displays (HMDs). 
     Referring to  FIG.  1   , the display device  10  may have a shape similar to a rectangular shape, in plan view. For example, the display device  10  may have a shape similar to a rectangular shape, in plan view, with short sides extending in the first direction X and long sides extending in the second direction Y. A corner where the short side in the first direction X and the long side in the second direction Y meet may be rounded with a predetermined curvature, or be right-angled. The shape of the display device  10  in plan view is not necessarily limited to the rectangular shape, and may be another polygonal shape, an irregular shape, a circular shape, or an elliptical shape. 
     A front surface and/or a rear surface of the display device  10  may be a display surface. In this embodiment, the “front surface” is a surface positioned on one side of one plane, and refers to a surface positioned on one side in the third direction Z in the drawings (e.g., toward a positive Z direction), and the “rear surface” is a surface positioned on the other side of one plane, and refers to a surface positioned on the other side in the third direction Z in the drawings. In some embodiments, the display device  10  is a double-sided display device  10  which displays images on both the front surface and the rear surface, but an embodiment in which the display surface is positioned on the front surface of the display device  10  will hereinafter be mainly described. 
     The display device  10  includes a display panel  100  providing a display screen, a display driver  200 , a circuit board  300 , and a touch driver  400 . 
     The display panel  100  may have a shape similar to a rectangular shape in plan view. For example, the display panel  100  may have a shape similar to a rectangular shape, in plan view, with short sides extending in the first direction X and long sides extending in the second direction Y. A corner where the short side in the first direction X and the long side in the second direction Y meet may be rounded with a predetermined curvature, or be right-angled. The shape of the display panel  100  in plan view is not necessarily limited to the rectangular shape, and may be another polygonal shape, an irregular shape, a circular shape, or an elliptical shape. In addition, the display panel  100  may also be formed flexibly so as to be bent without damage. 
     The display panel  100  may include a main area MA and a sub-area SBA. 
     The main area MA may include a display area DA including pixels configured to display an image and a non-display area NDA disposed around the display area DA. The display area DA may emit light from a plurality of emission areas or a plurality of opening areas. For example, the display panel  100  may include pixel circuits including switching elements, a pixel defining film defining the emission areas or opening areas, and self-light emitting elements. 
     The non-display area NDA may be disposed outside the display area DA. The non-display area NDA may be defined as an edge area of the main area MA of the display panel  100 . The non-display area NDA may include a gate driver configured to supply gate signals to gate lines. 
     The sub-area SBA may extend from one side of the main area MA. The sub-area SBA may be bent to wrap around and overlap the main area MA in the third direction Z. The sub-area SBA may include the display driver  200  and a pad part connected to the circuit board  300 . 
     Referring to  FIG.  2   , the display panel  100  includes a display unit DU and a touch unit TSU. 
     The display unit DU may include a plurality of pixels SP (see  FIG.  4   ). The pixel SP is a basic unit for displaying a screen (e.g., a color on a screen). The pixel SP may include a red pixel, a green pixel, and a blue pixel, but is not necessarily limited thereto. The plurality of pixels SP may be alternately arranged in plan view. For example, the pixels SP may be arranged in a matrix direction, but are not necessarily limited thereto. 
     The touch unit TSU may be disposed on the display unit DU. The touch unit TSU includes a plurality of touch electrodes RE and TE ( FIG.  5   ) for sensing a user’s touch in a capacitive manner, a plurality of touch driving lines TL connecting a plurality of driving electrodes TE and the touch driver  400  to each other, and a plurality of touch sensing lines RL. The touch unit TSU is a layer configured to sense a touch input and may function as a touch member. The touch unit TSU may determine whether or not the touch input has been generated, and may calculate a corresponding position of the touch input as touch input coordinates. A detailed description of the display unit DU and the touch unit TSU will be described later with reference to  FIGS.  4  to  7   . 
     The display unit DU and the touch unit TSU may overlap each other. For example, the display area DA may be an area in which both of the display of images and the sensing of the touch input are performed. The plurality of driving electrodes TE of the touch unit TSU may be disposed in a touch sensor area overlapping the display area DA. 
     The sub-area SBA of the display panel  100  may extend from one side of the main area MA. The sub-area SBA may include a flexible material may be bent, folded, and rolled. For example, when the sub-area SBA is bent, the sub-area SBA may overlap the main area MA in the third direction (Z-axis direction), as shown in  FIG.  2   . The sub-area SBA may include the display driver  200  and the pad part (DP in  FIG.  4   ) connected to the circuit board  300 . 
     Referring to  FIG.  1    again, the display driver  200  may be disposed in the non-display area NDA of the display panel  100 . In addition, the display driver  200  may be formed as an integrated circuit (IC) and be mounted on the display panel  100  in a chip on plastic (COP) manner or a chip on glass (COG) manner. The present disclosure is not necessarily limited thereto, however, and the display driver  200  may be mounted in various ways. 
     The display driver  200  may output data signals and voltages for driving the display panel  100 . The display driver  200  may supply data voltages to data lines. The display driver  200  may supply a source voltage to a power line and supply gate control signals to the gate driver. 
     The circuit board  300  may be disposed in the non-display area NDA of the display panel  100 . Lead lines of the circuit board  300  may be electrically connected to the pad part (DP,  FIG.  4   ) of the display panel  100 . The circuit board  300  may be a flexible film such as a flexible printed circuit board, a printed circuit board, or a chip on film. 
     The circuit board  300  may include a plurality of conductive lines for transferring signals from a main circuit board to the circuit board  300  and/or electrically connecting the touch driver  400  and a plurality of touch electrodes RE and TE of a touch layer to each other. 
     The touch driver  400  may be disposed in the non-display area NDA of the display panel  100 . The touch driver  400  may be mounted on the circuit board  300 . The touch driver  400  may supply touch driving signals TX to a plurality of touch electrodes of a touch panel and sense changes in capacitance between the plurality of touch electrodes. 
     The touch driver  400  may determine whether or not a touch input has been generated and calculate touch coordinates based on the sensed change in capacitance between the plurality of touch electrodes. The touch driver  400  may be formed as an integrated circuit (IC) and be mounted on the display panel  100  in a chip on plastic (COP) manner or a chip on glass (COG) manner. However, the present disclosure is not necessarily limited thereto, and the touch driver  400  may be mounted in various ways. 
       FIG.  3    is a block diagram that illustrates a display unit and a touch driver according to an embodiment.  FIG.  4    is a schematic plan view that illustrates the display unit of the display device according to an embodiment. 
     Referring to  FIGS.  3  and  4   , the display device  10  includes the display panel  100  including the plurality of pixels SP, the display driver  200 , and the touch driver  400 . 
     Referring to  FIG.  3   , the display driver  200  may include a gate driver  210 , a data driver  230 , a display controller  220 , and a frame frequency synchronization signal controller  240 . 
     The display controller  220  may receive input data R, G, and B, a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, and a frame frequency signal Sgn_f from outside of the display unit (e.g., a host). The input data R, G, and B may be RGB data including red image data, green image data, and blue image data. The display controller  220  may generate output data signals DR, DG, and DB and an internal control signal using the received data R, G, and B, vertical synchronization signal Vsync, horizontal synchronization signal Hsync, and frame frequency signal Sgn_f. 
     The internal control signal includes a data driver control signal DCS and a gate driver control signal GCS. 
     The display controller  220  may control operations of the data driver  230  by providing the data driver control signal DCS to the data driver  230 , control operations of the gate driver  210  by providing the gate driver control signal GCS to the gate driver  210 , and control operations of the frame frequency synchronization signal controller  240  by providing the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, and the frame frequency signal Sgn_f to the frame frequency synchronization signal controller  240 . 
     The data driver  230  may receive the output data signals DR, DG, and DB and the data driver control signal DCS from the display controller  220 . The data driver  230  may generate data signals using the received output data signals DR, DG, and DB and data driver control signal DCS, and provide the generated data signals to the display panel  100 . The data driver  230  may provide the data signals through a plurality of data lines DL1 to DLn (see  FIG.  3   ,  FIG.  4   ) connected to the display panel  100 . 
     The gate driver  210  may receive the gate driver control signal GCS from the display controller  220 . The gate driver  210  may generate gate signals using the received gate driver control signal GCS and provide the generated gate signals to the display panel  100 . The gate driver  210  may provide the gate signals through a plurality of gate lines GL1 to GLn (see  FIG.  4   ) connected to the display panel  100 . A detailed description of the plurality of data lines DL1 to DLn (see  FIG.  3   ,  FIG.  4   ) and the plurality of gate lines GL1 to GLn (see  FIG.  4   ) will be described later with reference to  FIG.  4   . 
     The gate driver  210 , the data driver  230 , and the display controller  220  may be included in the display driver  200  which controls operations of the display panel  100 . In some embodiments, the gate driver  210 , the data driver  230 , and the display controller  220  may be formed as integrated circuits (ICs) and be mounted on the display driver  200 . 
     The display panel  100  may receive the data signals from the data driver  230  and receive the gate signals from the gate driver  210 . The display panel  100  may include the plurality of pixels SP (see  FIG.  3   ) connected to the plurality of data lines DL1 to DLn (see  FIG.  3   ,  FIG.  4   )) and to the plurality of gate lines GL1 to GLn (see  FIG.  3   ,  FIG.  4   ). 
     The frame frequency synchronization signal controller  240  may receive the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, and the frame frequency signal Sgn_f from the display controller  220 . 
     The frame frequency synchronization signal controller  240  may generate a frame frequency synchronization signal Hsync_f using the received vertical synchronization signal Vsync, horizontal synchronization signal Hsync, and frame frequency signal Sgn_f, and may provide the generated frame frequency synchronization signal Hsync_f to the touch driver  400 . The frame frequency synchronization signal controller  240  may provide the frame frequency synchronization signal Hsync_f through a plurality of frame frequency synchronization signal lines connected to the touch driver  400 . 
     The frame frequency synchronization signal controller  240  may be formed integrally with the display controller  220 . For example, the frame frequency synchronization signal controller  240  may be formed in the same circuit and/or in the same package as the display controller  220 . In some embodiments, the frame frequency synchronization signal controller  240  may be formed as an integrated circuit (IC) and be mounted on the display driver  200  and/or the display controller  220 . 
     Meanwhile, a frame frequency input to the display driver  200  may vary. For example, the frame frequency may vary within the range of 1 Hz to 240 Hz according to, for example, a host’s or user’s selection. The display driver  200  may be driven at 60 Hz for one section and change the frame frequency to 120 Hz for another section according to the user’s need. 
     Accordingly, the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, and the frame frequency signal Sgn_f received by the frame frequency synchronization signal controller  240  of the display driver  200  may also vary in order to change the frame frequency according to the host’s or user’s selection. The varying frame frequency signal Sgn_f corresponds to the frame frequency synchronization signal Hsync_f, which corresponds to a frame frequency stored in a memory, and accordingly, the frame frequency synchronization signal Hsync_f generated by the frame frequency synchronization signal controller  240  may also vary. 
     The touch driver  400  may receive the frame frequency synchronization signal Hsync_f from the frame frequency synchronization signal controller  240 . The touch driver  400  may also receive the vertical synchronization signal Vsync through the plurality of frame frequency synchronization signal lines. 
     As described above, the touch unit TSU may be disposed on the display unit DU so as to overlap the display unit DU. Accordingly, when the spacing between the touch unit TSU and the display unit DU is small, electrical interactions may exist between the gate signals and the data signals of the display driver  200  and touch driving signals TX and touch sensing signals RX of the touch unit. Therefore, any one signal may serve as noise for another signal. For example, in the touch driving signals TX and the touch sensing signals RX, the gate signals and the data signals may cause display noise. The touch driver  400  may generate the touch driving signals TX so as to avoid such display noise. For example, even though the frame frequency varies, an influence of the noise on the touch driving signals TX from the display panel  100  may be minimized. A detailed description of the touch driver  400  will be described later with reference to  FIG.  5   . 
     Referring to  FIG.  4   , the display unit DU may include a display area DA and a non-display area NDA. The display unit DU may include the plurality of pixels SP and the plurality of gate lines GL1 to GLn and the plurality of data lines DL1 to DLn connected to the plurality of pixels SP. 
     The plurality of gate lines GL1 to GLn may supply the gate signals received from the gate driver  210  to the plurality of pixels SP. Each of the plurality of gate lines GL1 to GLn may extend in the first direction X, and may be spaced apart from each other in the second direction Y. 
     The plurality of data lines DL1 to DLn may supply the output data signals DR, DG, and DB and the data signals received from the display driver  200  to the plurality of pixels SP. The plurality of data lines DL1 to DLn may extend in the second direction Y, and may be spaced apart from each other in the first direction X. 
     The non-display area NDA may surround the display area DA. The non-display area NDA may include the gate driver  210  configured to supply the gate signals to the plurality of gate lines GL1 to GLn, fan-out lines FOL connecting the plurality of data lines DL1 to DLn and the display driver  200  to each other, and display pad parts DP connected to the circuit board  300 . 
     The display driver  200  may supply the gate driver control signal GCS to the gate driver  210  through a gate control line GCL, as described above. The gate driver  210  may generate a plurality of gate signals based on the gate driver control signal GCS, and may sequentially supply the plurality of gate signals to the plurality of gate lines GL1 to GLn according to a set order. 
     In some embodiments, each of the plurality of pixels SP may receive a first source voltage and a second source voltage. The first source voltage may be a predetermined high level voltage, and the second source voltage may be a voltage lower than the first source voltage. 
     A display pad area DPA and a touch pad area TPA may be disposed at an edge of the display panel  100 . The display pad area DPA may include a plurality of display pad parts DP. The plurality of display pad parts DP may be connected to a main processor through the circuit board  300 . The plurality of display pad parts DP may be connected to the circuit board  300  and receive digital video data, and may supply the digital video data to the display driver  200 . 
       FIG.  5    is a plan view that illustrates a touch unit of the display device according to an embodiment. 
     Referring to  FIG.  5   , the touch unit TSU may include a touch area TSA configured to sense a user’s touch, and a touch peripheral area TPA disposed around the touch area TSA. The touch area TSA may overlap the display area DA of the display panel  100 , and the touch peripheral area TPA may overlap the non-display area NDA of the display panel  100 . 
     Referring to  FIG.  5   , the touch area TSA may include a plurality of touch electrodes RE and TE and a plurality of touch signal lines RL and TL. The touch area TSA may sense a touch input by receiving electrical signals from the touch driver  400  disposed on the circuit board  300  through the plurality of touch signal lines RL and TL and transmitting electrical signals sensed from the plurality of touch electrodes RE and TE to the touch driver  400  through the plurality of touch signal lines RL and TL. 
     A plurality of driving electrodes TE may be arranged in the first direction (X-axis direction) and the second direction (Y-axis direction). The plurality of driving electrodes TE may be spaced apart from each other in the first direction (X-axis direction) and the second direction (Y-axis direction). The driving electrodes TE adjacent to each other in the second direction (Y-axis direction) may be electrically connected to each other through a bridge electrode CE. 
     The plurality of driving electrodes TE disposed in the touch area TSA may be connected to the touch pad parts TP through the touch driving lines TL. A plurality of driving lines TL may pass through a lower side of the touch peripheral area TPA and/or may extend to the touch pad parts TP via an upper side, a left side, and a lower side of the touch peripheral area TPA. The touch pad parts TP may be connected to the touch driver  400  through the circuit board  300 . 
     The display pad area DPA and the touch pad area TPA may be disposed at an edge of the sub-area SBA of the display panel  100 . The display pad area DPA and the touch pad area TPA may be electrically connected to the circuit board  300  using a low-resistance and high-reliability material such as an anisotropic conductive film. 
     A plurality of sensing electrodes RE may extend in the first direction (X-axis direction) and may be spaced apart from each other in the second direction (Y-axis direction). The plurality of sensing electrodes RE may be arranged in the first direction (X-axis direction) and the second direction (Y-axis direction), and the plurality of sensing electrodes RE adjacent to each other in the first direction (X-axis direction) may be electrically connected to each other through a connection part (e.g., the connection structure CP as illustrated within the bridge electrode CE in  FIG.  5   ). 
     The plurality of sensing electrodes RE may be connected to the touch pad parts TP through the plurality of touch sensing lines RL. For example, the plurality of sensing electrodes RE may be connected to the touch pad parts TP through the plurality of touch sensing lines RL disposed on the right side of the touch sensor area TSA. The plurality of touch sensing lines RL may extend to the touch pad parts TP via a right side and a lower side of the touch peripheral area TPA. The touch pad parts TP may be connected to the touch driver  400  through the circuit board  300 . 
     The plurality of touch electrodes RE and TE may not cause display artifacts from a display layer by including a planar pattern formed of a transparent conductive layer or a mesh pattern in which an opaque metal is used along an area in which light emitting elements are not disposed. 
     The touch driving signal TX may be applied to each of the plurality of driving electrodes TE from the touch driver  400  through any one of the plurality of touch driving lines TL. The touch driver  400  may receive the frame frequency synchronization signal Hsync_f and output the touch driving signal TX corresponding to a duty value  720   a  (see  FIG.  13   ). Thereafter, a mutual capacitance may be formed between the driving electrode TE and the sensing electrode RE adjacent to it. When a touch input is generated from the outside, a mutual capacitance value between the driving electrode TE and the sensing electrode RE adjacent to each other may change. The change in the mutual capacitance measured by the plurality of sensing electrodes RE may be transferred to the touch driver  400  through the plurality of touch sensing lines RL. Accordingly, the touch driver  400  may determine whether or not the touch input has been made, if it is determined a touch input has been made, calculate a corresponding position as touch input coordinates. The touch sensing may be performed in a mutual capacitive manner, but is not necessarily limited thereto. 
       FIG.  6    is a detailed block diagram of a frame frequency synchronization signal controller according to an embodiment. The frame frequency synchronization signal controller  240  of the display driver  200  will be described with reference to  FIG.  6   . 
     Referring to  FIG.  6   , the frame frequency synchronization signal controller  240  may include a signal identifier  241 , a clock generator  242 , a voltage generator  243 , a synchronization signal generator  244 , and a memory  245 . 
     The signal identifier  241  may identify a porch section  710   a  (see  FIG.  13   ) of the frame frequency signal Sgn_f and the vertical synchronization signal Vsync using the received vertical synchronization signal Vsync, horizontal synchronization signal Hsync, and frame frequency signal Sgn_f, and generate a synchronization signal generation signal for adjusting the horizontal synchronization signal Hsync in the porch section  710   a  (see  FIG.  13   ). The porch section may be referred to as a “blank” section (see  FIG.  12   ). The signal identifier  241  may provide the generated synchronization signal generation signal to the synchronization signal generator  244 . 
     The clock generator  242  may output a clock signal. The output clock signal may be provided to the synchronization signal generator  244 . The voltage generator  243  may generate a voltage signal used for generating the frame frequency synchronization signal Hsync_f and supply the voltage signal to the synchronization signal generator  244 . 
     The synchronization signal generator  244  may receive the clock signal from the clock generator  242  and receive the voltage signal from the voltage generator  243 . The synchronization signal generator  244  may receive the synchronization signal generation signal from the signal identifier  241  and output the frame frequency synchronization signal Hsync_f according to a duty value corresponding to a frame frequency stored in the memory using the received clock signal and voltage signal, and may provide the vertical synchronization signal Vsync and the frame frequency synchronization signal Hsync_f to the touch driver  400 . 
     The duty value refers to a pulse width of the horizontal synchronization signal Hsync in the porch section  710   a  (see  FIG.  13   ) of the vertical synchronization signal Vsync. For example, the vertical synchronization signal Vsync may include a synchronization signal section having a first signal waveform, and the porch section  710   a  (see  FIG.  13   ) having a second signal waveform different from the first signal waveform. The frame frequency synchronization signal Hsync_f may include a first section corresponding to the synchronization signal section and a second section corresponding to the porch section  710   a  (see  FIG.  13   ), and the second section may include a third signal waveform different from the first signal waveform and the second signal waveform, and contain the frame frequency information. These waveforms will be described later. 
     For example, the duty value  720   a  (see  FIG.  13   ) may be greater than a pulse width of a plurality of horizontal synchronization signals Hsync. For example, when one pulse width of the horizontal synchronization signal Hsync is 1 H, the duty value  720   a  (see  FIG.  13   ) may have a pulse width that is greater than a pulse width of at least 3 H to 4 H, and may be less than or equal to a pulse width of 100 H. 
     The memory  245  may store the duty value of the frame frequency synchronization signal Hsync_f according to the frame frequency. The memory  245  may be configured in the form of a lookup table. 
     For example, when the display driver  200  controls the display panel  100  at 240 Hz, the memory  245  may be configured in the form of a lookup table so that the duty value  720   a  (see  FIG.  13   ) of the frame frequency synchronization signal Hsync_f in the porch section  710   a  (see  FIG.  13   ) of the vertical synchronization signal Vsync is 24 µs. In this way, the frame frequency synchronization signal controller  240  may adjust the driving signals of the touch driver  400  so as to compensate for the changing refresh rate of the display panel  100 , thereby reducing noise in the touch driving signals, and providing increased touch reliability. 
     The signal identifier  241 , the clock generator  242 , the voltage generator  243 , the synchronization signal generator  244 , and the memory  245  may be formed as integrated circuits (ICs) and be formed integrally with the synchronization signal generator  244 , or be separate units mounted on the synchronization signal generator  244 , or some combination thereof. 
     The frame frequency synchronization signal controller  240  varies pulse widths of a signal of at least one of the signal identifier  241 , the clock generator  242 , and the voltage generator  243  according to the frame frequency, and outputs the signal of which the pulse widths vary to the synchronization signal generator  244 . The duty value of the frame frequency synchronization signal Hsync_f corresponds to the duty value corresponding to the frame frequency stored in the memory, such that the frame frequency synchronization signal Hsync_f may have different duty values according to the frame frequencies in the porch section  710   a  (see  FIG.  13   ) of the vertical synchronization signal Vsync. 
     With the display device according to an embodiment, even though the frame frequency at which the display driver  200  controls the display panel  100  varies, the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, and the frame frequency signal Sgn_f received by the frame frequency synchronization signal controller  240  may also vary in response to compensate. Accordingly, the frame frequency synchronization signal controller  240  may generate the varying frame frequency synchronization signal Hsync_f and provide the varying frame frequency synchronization signal Hsync_f to the touch driver  400 . In this way, effects from noise of the display signals on the touch driving signals may be mitigated, touch input reliability may be increased, and touch input sensitivity may be maintained. 
       FIG.  7    is a detailed block diagram of the touch driver according to an embodiment. 
     The touch driver  400  may include a touch controller  410 , a touch driving signal unit  420 , and a sensing unit  430 . 
     The touch controller  410  may include a synchronization signal receiver  411 , a clock generator  412 , a voltage generator  413 , and a signal adjuster  414 . 
     The touch controller  410  may supply a touch driving control signal for driving the touch driving signal unit  420  to the touch driving signal unit  420 . For example, when a duty value (e.g., a data value stored in the memory) according to the vertical synchronization signal Vsync and the frame frequency synchronization signal Hsync_f is input from the frame frequency synchronization signal controller  240 , the touch controller  410  transmits a predetermined touch driving control signal value to the touch driving signal unit  420 . 
     The touch controller  410  may control driving timings of the touch driving signal unit  420  and the sensing unit  430 . The touch controller  410  may output timing signals for synchronization according to frame frequencies of the touch driving signal unit  420  and the sensing unit  430 . The touch controller  410 , the touch driving signal unit  420 , and the sensing unit  430  may be formed as separate or integral integrated circuits (ICs) and be mounted on the touch driver  400 . 
     The synchronization signal receiver  411  receives the vertical synchronization signal Vsync and the frame frequency synchronization signal Hsync_f in order to generate the touch driving control signal. For example, when the vertical synchronization signal Vsync and the frame frequency synchronization signal Hsync_f are input from the frame frequency synchronization signal controller  240 , the synchronization signal receiver  411  may identify a duty value of the frame frequency synchronization signal Hsync_f and generate a signal adjustment control signal for adjusting the touch driving signal TX according to the frame frequency. The synchronization signal receiver  411  may then provide the generated signal adjustment control signal to the signal adjuster  414 . 
     The clock generator  412  may output a clock signal and provide the clock signal to the signal adjuster  414 . The voltage generator  413  may generate a voltage signal used for generating the frame frequency synchronization signal Hsync_f and supply the voltage signal to the signal adjuster  414 . 
     The signal adjuster  414  may receive the clock signal from the clock generator  412  and receive the voltage signal from the voltage generator  413 . The signal adjuster  414  may receive the signal adjustment control signal from the synchronization signal receiver  411  and identify a frame frequency according to a preset duty value (e.g., a data value included in a lookup table stored in the memory). The signal adjuster  414  may output the touch driving control signal according to a touch driving pulse corresponding to the frame frequency using the identified frame frequency and the received clock signal and voltage signal, and provide the touch driving control signal to the touch driving signal unit  420 . 
     The synchronization signal receiver  411 , the clock generator  412 , the voltage generator  413 , and the signal adjuster  414  may be formed as integrated circuits (ICs) and be formed integrally with the touch controller  410  or be mounted on the touch controller  410 . In some embodiments, one or more of the components described with reference to  FIG.  7    may be implemented in a single integrated circuit, may be implemented as separate circuits, or some combination of combined and individual circuits. 
     The touch driving signal unit  420  may include a driving signal generator  421  and a touch driving signal applier  422 . 
     The touch driving signal unit  420  may be connected to the plurality of driving electrodes TE through the plurality of touch driving lines TL. The touch driving signal unit  420  may supply the touch driving signals TX to the plurality of driving electrodes TE. The touch driving signal TX may have a plurality of driving pulses. The touch driving signal unit  420  may supply the touch driving signals TX to the plurality of touch driving lines TL. For example, the touch driving signal unit  420  may sequentially output the touch driving signals TX from the plurality of driving electrodes TE disposed on one side of the touch panel to the plurality of driving electrodes TE disposed on the other side of the touch panel. 
     The touch driving signal generator  421  may receive the touch driving control signal adjusted according to the frame frequency by the signal adjuster  414  and generate the touch driving signals TX according to each frame frequency. 
     The touch driving signal applier  422  may supply the touch driving signals TX received from the touch driving signal generator  421  through the plurality of touch driving lines TL to the plurality of driving electrodes TE. For example, the touch driving signal applier  422  may sequentially output the touch driving signals TX from the plurality of driving electrodes TE disposed on one side of the touch panel to the plurality of driving electrodes TE disposed on the other side of the touch panel. 
     The sensing unit  430  may include an analog front end  431 , an analog-to-digital converter  432 , and a digital processor  433 . 
     The sensing unit  430  may be connected to the plurality of sensing electrodes RE through the plurality of touch sensing lines RL. The sensing unit  430  may sense amounts of change in mutual capacitance between the plurality of driving electrodes TE and the plurality of sensing electrodes RE through the plurality of touch sensing lines RL. For example, the sensing unit  430  may include an integrated circuit including at least one operational amplifier configured to sense a change in capacitance from the sensing electrode RE of the touch unit TSU and a capacitor with a predetermined capacitance. An inverting input terminal of the operational amplifier may be connected to the sensing electrode RE to output the change in capacitance as an analog signal. 
     The analog signal received by the analog front end  431  may be converted into a digital signal. The analog front end  431  may include a capacitor, a switch, a resistor, an amplifier, and a sample and holder. The implementation form of the analog front end  431  is not necessarily limited to the one described here. For example, in one embodiment, a voltage corresponding to electric charges charged in the capacitor may be sampled by the sample and holder, and then held for a predetermined period. 
     The analog-to-digital converter  432  may convert an output of the analog front end  431  to generate sensed data. The analog-to-digital converter  432  may convert a sampled signal into digital data and output the digital data. 
     In addition, the digital processor  433  may process the sensed data to generate touch data TD. 
     The sensing unit  430  may be controlled by the touch controller  410  in order to sense a touch signal using the analog front end  431 , the analog-to-digital converter  432 , and the digital processor  433 . 
     The analog front end  431 , the analog-to-digital converter  432 , and the digital processor  433  may be formed as integrated circuits (ICs) and be formed integrally with the sensing unit  430  or be mounted on the sensing unit  430 . In some embodiments, the analog front end  431 , the analog-to-digital converter  432 , and the digital processor  433  may each be formed as separate integrated circuits. In other embodiments, they may be implemented in a single integrated circuit. 
     Accordingly, as the frame frequency input to the display driver  200  varies, the frame frequency synchronization signal Hsync_f generated by the frame frequency synchronization signal controller  240  may also vary. The touch driver  400  may receive the varying frame frequency synchronization signal Hsync_f and output the touch driving signal TX corresponding to the duty value of the frame frequency synchronization signal Hsync_f. Accordingly, in some embodiments, by changing the touch driving signal TX in response to the frame frequency input to the display driver  200 , effects from noise of the display signals on the touch driving signals may be mitigated, touch input reliability may be increased, and touch input sensitivity may be maintained. 
       FIG.  8    is a block diagram that illustrates a relationship between a display driver and the touch driver according to an embodiment.  FIGS.  9  and  10    are timing diagrams that illustrate a method of driving the display driver according to an embodiment. 
     Referring to  FIG.  8   , the touch driver  400  may receive the vertical synchronization signal Vsync and the frame frequency synchronization signal Hsync_f from the display driver  200  and determine a section in which the gate signals and the data signals are transmitted. 
     For example, the display driver  200  and the touch driver  400  may transmit and receive signal information to and from each other through a plurality of signal lines, respectively. The plurality of signal lines may include a vertical synchronization signal information line Vsyncl and a horizontal synchronization signal information line Hsyncl. For example, the plurality of signal lines may be connected to the touch driver  400  and the display driver  200  in a manner in which output/input pins GPIO 1  and GPIO 2  disposed at both ends thereof are coupled to the touch driver  400  and the display driver  200 , respectively. For example, an output pin GPIO 1   a  of the vertical synchronization signal information line Vsyncl may be connected to the display driver  200  (e.g., to the frequency synchronization signal controller  240  of the display driver  200 ), and an input pin GPIO 2   a  of the vertical synchronization signal information line Vsyncl may be connected to the touch driver  400  (e.g., to the touch controller  410  of the touch driver  400 ). 
     In addition, an output pin GPIO lb  of the horizontal synchronization signal information line Hsyncl may be connected to the display driver  200  (e.g., to the frequency synchronization signal controller  240  of the display driver  200 ), and an input pin GPIO 2   b  of the horizontal synchronization signal information line Hsyncl may be connected to the touch driver  400  (e.g., to the touch controller  410  of the touch driver  400 ). Each of the vertical synchronization signal Vsync and the frame frequency synchronization signal Hsync_f provided from the display driver  200  to the touch driver  400  may be transmitted as a voltage signal having a pulse form having a preset duty value. 
     The duty value of the frame frequency synchronization signal Hsync_f supplied from the display driver  200  to the touch driver  400  may vary. For example, the display driver  200  may include the frame frequency synchronization signal controller  240  in order to vary the duty value of the frame frequency synchronization signal Hsync_f.The frame frequency synchronization signal controller  240  may adjust the output the frame frequency synchronization signal Hsync_f by adjusting the duty value. The frame frequency synchronization signal controller  240  may be electrically connected to the output pin GPIO lb  of the horizontal synchronization signal information line Hsyncl. 
     However, a duty value of the corresponding vertical synchronization signal Vsync and/or frame frequency synchronization signal Hsync_f for each frame frequency may be adjusted to have a preset duty value (e.g., a data value in the form of a lookup table stored in the memory). For example, as the frame frequency decreases, the duty value of the corresponding vertical synchronization signal Vsync and/or frame frequency synchronization signal Hsync_f may be set to decrease, but the disclosure is not necessarily limited thereto. 
     For example, the frame frequency of the display panel  100  may vary within a range of 1 Hz to 240 Hz. In some embodiments, the display driver  200  may control the display panel  100  to be driven at three or more frequencies within the range described above. For example, the display device  10  may be selectively driven at frame frequencies of 60 Hz, 120 Hz, 180 Hz, 200 Hz, and 240 Hz according to host’s or user’s selection, or to a preconfigured response to usage or to an application, or the like. 
     The frame frequency may vary in several forms. For example, the display driver  200  may control the display panel  100  to be driven at 60 Hz for one section and to be driven at 120 Hz for another section. However, a frequency at which the display panel  100  is driven is not necessarily limited to the frame frequency described above. 
     The touch driver  400  may receive the vertical synchronization signal Vsync and the frame frequency synchronization signal Hsync_f from the display driver  200  by adjusting the duty value of the frame frequency synchronization signal Hsync_f.The touch driving signal TX adjusted according to the varying frame frequency may be provided to the touch driver  400 . 
     In an embodiment, the duty value of the vertical synchronization signal Vsync and/or frame frequency synchronization signal Hsync_f recognized by the touch driver  400  may be adjusted to recognize a preset duty value (e.g., a data value in the form of a lookup table stored in the memory). For example, as the frame frequency decreases, the duty value of the corresponding vertical synchronization signal Vsync and/or frame frequency synchronization signal Hsync_f may be set to decrease, but the relationship of the duty value to the frame frequency is not necessarily limited thereto. 
     In addition, the vertical synchronization signal Vsync may include a synchronization signal section having a first signal waveform, and the porch section  710   a  (see  FIG.  13   ) having a second signal waveform different from the first signal waveform. The frame frequency synchronization signal Hsync_f may include a first section corresponding to the synchronization signal section and a second section corresponding to the porch section  710   a  (see  FIG.  13   ), and the second section may include a third signal waveform different from the first signal waveform and the second signal waveform, and may have frame frequency information. These waveforms will be described later. 
     Referring to  FIGS.  9  and  10   , as described above, the touch driver  400  may receive the frame frequency synchronization signal Hsync_f having various duty values from the display driver  200 . The touch driver  400  may recognize at which frequency the display driver  200  is currently controlling the display panel  100  based on the duty value of the frame frequency synchronization signal Hsync_f received from the display driver  200 . 
     For example, when the duty value of the frame frequency synchronization signal Hsync_f of the horizontal synchronization signal Hsync provided to the touch driver  400  is 24 µs, the touch driver  400  may recognize that the display driver  200  is controlling the display panel  100  at 240 Hz. 
     In some examples, when the duty value of the frame frequency synchronization signal Hsync_f of the horizontal synchronization signal Hsync provided to the touch driver  400  is 20 µs, the touch driver  400  may recognize that the display driver  200  is controlling the display panel  100  at 200 Hz. 
     In some examples, when the duty value of the frame frequency synchronization signal Hsync_f of the horizontal synchronization signal Hsync provided to the touch driver  400  is 18 µs, the touch driver  400  may recognize that the display driver  200  is controlling the display panel  100  at 180 Hz. 
     In some examples, when the duty value of the frame frequency synchronization signal Hsync_f of the horizontal synchronization signal Hsync provided to the touch driver  400  is 12 µs, the touch driver  400  may recognize that the display driver  200  is controlling the display panel  100  at 120 Hz. 
     In some examples, when the duty value of the frame frequency synchronization signal Hsync_f of the horizontal synchronization signal Hsync provided to the touch driver  400  is 6 µs, the touch driver  400  may recognize that the display driver  200  is controlling the display panel  100  at 60 Hz. 
     When one pulse width of the vertical synchronization signal Hsync is 1 H, the duty value  720   a  (see  FIG.  13   ) may be greater than a pulse width of a plurality of vertical synchronization signals Hsync. For example, the duty value  720   a  (see  FIG.  13   ) may have a pulse width greater than a pulse width of at least 3 H to 4 H. 
     A section in which the touch driver  400  outputs the touch driving signal TX according to the corresponding duty value of the frame frequency synchronization signal Hsync_f may not overlap a period in which the display driver  200  provides the gate signals to the display panel  100  and/or a period in which the display driver  200  provides the data signals to the display panel  100 . 
     In the display device according to the embodiment, as the frame frequency input to the display driver  200  varies, the frame frequency synchronization signal Hsync_f generated by the frame frequency synchronization signal controller  240  may also vary. The varying frame frequency synchronization signal Hsync_f may be provided to the touch driver  400  through the horizontal synchronization signal information line Hsyncl and the vertical synchronization signal information line Vsyncl. The touch driver  400  may receive the varying frame frequency synchronization signal Hsync_f and output the touch driving signal TX corresponding to the duty value of the frame frequency synchronization signal Hsync_f. 
       FIGS.  11  and  12    are flowcharts for describing operations of the display device.  FIG.  13    is a timing diagram that illustrates signals of the display device according to an embodiment. 
     Referring to  FIG.  11   , first, signals corresponding to a first frame frequency  600   a  are received from the display driver  200  by the frame frequency synchronization signal controller  240  (S 301 ). 
     For example, the signals corresponding to the first frame frequency  600   a  may be the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, and the frame frequency signal Sgn_f. The first frame frequency  600   a  may be a frame frequency of a screen to be displayed on the display panel  100 . For example, the first frame frequency  600   a  may be 60 Hz. 
     Then, a first frame frequency synchronization signal Hsync_f is generated based on a frame frequency in the porch section  710   a  of the vertical synchronization signal Vsync (S 302 ). 
     In some embodiments, the first frame frequency synchronization signal Hsync_f is generated based on the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, and the frame frequency signal Sgn_f received from the display driver  200 . In this case, duty values of the vertical synchronization signal Vsync and the frame frequency synchronization signal Hsync_f correspond to the duty values corresponding to the frame frequencies stored in the memory. Accordingly, the first frame frequency synchronization signal Hsync_f having the duty value according to the frame frequency is generated in the porch section  710   a  of the vertical synchronization signal Vsync. 
     In this example, the vertical synchronization signal Vsync may include a synchronization signal section having a first signal waveform and the porch section  710   a  (see  FIG.  13   ) having a second signal waveform different from the first signal waveform. The frame frequency synchronization signal Hsync_f may include a first section corresponding to the synchronization signal section and a second section corresponding to the porch section  710   a  (see  FIG.  13   ), and the second section may include a third signal waveform different from the first signal waveform and the second signal waveform and having frame frequency information. 
     Then, the first frame frequency synchronization signal is applied to the touch controller (S 303 ). 
     Referring to  FIGS.  11  and  13   , a signal output from the display driver  200  and received by the touch controller  410  may include the vertical synchronization signal Vsync and the first frame frequency synchronization signal Hsync_f.In some examples, the synchronization signal received from the display driver  200  by the touch driver  400  may further include a data enable (DE) signal and/or a tearing effect (TE) signal. A first touch driving signal Txla is applied to the touch unit TSU by the touch driver  400 . 
     In a section in which the frame frequency of the screen to be displayed on the display panel  100  is the first frame frequency  600   a , the first touch driving signal Txla may be applied to the touch unit TSU. The first touch driving signal Txla may be based on the section in which the vertical synchronization signal Vsync and the first frame frequency synchronization signal Hsync_f are applied, e.g. the section which the frame frequency of the screen to be displayed on the display panel  100  is the first frame frequency  600   a . When the vertical synchronization signal Vsync and the first frame frequency synchronization signal Hsync_f corresponding to the first frame frequency  600   a  are received from the display driver  200 , the touch controller  410  included in the touch driver  400  may apply the first touch driving signal Txla to the touch unit TSU based on the section in which the synchronization signals are applied. 
       FIG.  12    is a flowchart for describing operations of the display device. 
     The operations of the display device of  FIG.  12    may further include operations in which the frame frequency varies to a second frame frequency in the operations of the first frame frequency  600   a  of  FIG.  11   . S 401  to S 403  are substantially similar to S 301  to S 303  of  FIG.  11   , and an overlapping description thereof will be omitted to avoid redundancy. 
     Referring to  FIGS.  12  and  13   , first, signals corresponding to a second frame frequency  700   a  are received from the display driver  200  by the frame frequency synchronization signal controller  240  (S 404 ). 
     For example, the signals corresponding to the second frame frequency  700   a  may be the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, and the frame frequency signal Sgn_f. The second frame frequency  700   a  may be a frame frequency of a screen to be displayed on the display panel  100 . The second frame frequency  700   a  may be higher than the first frame frequency  600   a . For example, when the first frame frequency  600   a  is 60 Hz, the second frame frequency  700   a  may be 120 Hz. 
     Then, a second frame frequency synchronization signal Hsync_f is generated based on a frame frequency in the porch section  710   a  of the vertical synchronization signal Vsync (S 405 ). 
     For example, the second frame frequency synchronization signal Hsync_f is generated based on the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, and the frame frequency signal Sgn_f received from the display driver  200 . A first duty value  620   a  corresponding to a first display frequency may be generated before a display frequency is updated. In this case, duty values of the vertical synchronization signal Vsync and the frame frequency synchronization signal Hsync_f correspond to the duty values corresponding to the frame frequencies stored in the memory. Accordingly, the second frame frequency synchronization signal Hsync_f having the duty value  720   a   according to the second frame frequency  700   a  is generated in the porch section  710   a  of the vertical synchronization signal Vsync. 
     Then, the second frame frequency synchronization signal is applied to the touch controller (S 406 ). 
     Referring to  FIG.  13   , a signal received from the display driver  200  by the touch controller  410  may include the vertical synchronization signal Vsync and the second frame frequency synchronization signal Hsync_f.In some embodiments, the synchronization signal received from the display driver  200  by the touch driver  400  may further include at least one of a data enable (DE) signal and a tearing effect (TE) signal. 
     The first touch driving signal Txla may be applied to the touch unit TSU in a section in which the frame frequency of the screen to be displayed on the display panel  100  is the second frame frequency  700   a . The first touch driving signal Txla may be based on a section in which the vertical synchronization signal Vsync and the second frame frequency synchronization signal Hsync_f are applied, e.g. the section which the frame frequency of the screen to be displayed on the display panel  100  is the second frame frequency  700   a . When the vertical synchronization signal Vsync and the second frame frequency synchronization signal Hsync_f corresponding to the second frame frequency  700   a  are received from the display driver  200 , the touch controller  410  included in the touch driver  400  may apply the first touch driving signal Txla to the touch unit TSU based on the section in which the synchronization signals are applied. 
     In the section which the frame frequency of the screen to be displayed on the display panel  100  is the second frame frequency  700   a , pulses of the first touch driving signal Txla may not overlap pulses of the vertical synchronization signal Vsync and the second frame frequency synchronization signal Hsync_f.This may reduce possible noise interference of the synchronization frequencies with the touch driving signals. 
     In  FIG.  13   , display noise generated in the pixels SP arranged in a column direction is exemplified as noise for the touch driving signal TX acting from the display unit DU. As described above, when the touch unit TSU is disposed on the display unit DU so as to overlap the display unit DU and the spacing between the touch unit TSU and the display unit DU is small, and when the intervals of the display driving signals and the touch driving signals are rapid, electrical interactions may exist between the gate signals and the data signals of the display driver  200  and the touch driving signals TX and the touch sensing signals RX of the touch unit. Therefore, any one signal may serve as noise for another signal. For example, in the touch driving signals TX and the touch sensing signals RX, the gate signals and the data signals may act as the display noise, and the touch driving signals TX are affected by noise when the data signals are provided to the pixels SP arranged in the column direction. The gate signals and the data signals may act as the display noise for the touch driving signals TX and the touch sensing signals RX. In this case, touch accuracy and/or sensitivity may be reduced. 
     Accordingly, the display driver  200  according to the present disclosure may provide the vertical synchronization signal Vsync and the second frame frequency synchronization signal Hsync_f to the touch controller  410  so as to apply the second touch driving signal T x   2   a  in a display noise section  730   a  generated in a section in which the gate signals and the data signals are transmitted. 
     Therefore, when the vertical synchronization signal Vsync and the second frame frequency synchronization signal Hsync_f are received from the display driver  200 , the touch controller  410  may apply the second touch driving signal T x   2   a  to the touch unit TSU during the display noise section  730   a . The touch controller  410  may not apply the first touch driving signal to the touch controller  410  during the display noise section  730   a . Pulses of the second touch driving signal T x   2   a  may not overlap the pulses of the vertical synchronization signal Vsync and the second frame frequency synchronization signal Hsync_f. 
     In some cases, the gate signals and the data signals may act as the display noise for the touch driving signals TX and the touch sensing signals RX. 
     Accordingly, the frame frequency synchronization signal controller  240  may provide the vertical synchronization signal Vsync and the frame frequency synchronization signal Hsync_f to the touch driver  400  in order to recognize the section in which the gate signals and the data signals according to the frame frequency are transmitted, and the touch driver  400  may receive the above-described signals and generate the touch driving signals TX so as to avoid the display noise according to the section in which the gate signals and the data signals are transmitted. For example, even though the frame frequency varies, an influence of the noise on the touch driving signals TX acting from the display panel  100  may be minimized. 
     For example, even though the frame frequency at which the display driver  200  controls the display panel  100  varies, an influence of the display noise section  730   a  on the touch driving signals TX acting from the display panel  100  may be minimized, and the touch controller  410  may accurately recognize a user’s touch input. In addition, distortion of the touch driving signals TX due to the data signals may be decreased, and distortion of an image quality may be minimized while maintaining reliability of touch sensitivity. 
       FIGS.  14  and  15    are flowcharts that illustrate a method of driving the touch driver according to embodiments. 
     Referring to  FIG.  14   , first, frame frequency information is received (S 101 ). 
     The touch controller  410  may receive the vertical synchronization signal Vsync and the frame frequency synchronization signal Hsync_f from the frame frequency synchronization signal controller  240  of the display driver  200  through a communication interface in order to recognize frame frequency information. 
     Then, the touch controller  410  adjusts the touch driving signals (S 102 ). 
     The adjusting (S 102 ) of the touch driving signals includes adjusting the touch driving control signal in order to adjust voltage values of the touch driving signals TX by providing voltage change values according to voltage changes of the touch driving signals TX according to the respective frame frequency signals Sgn_f received in the receiving (S 101 ) of the frame frequency information, and is performed by the touch controller  410 . 
     In this example, the voltage changes of the touch driving signals TX according to the frame frequencies include, for example, voltage change values derived by performing a predetermined simulation through a software method in a separate device, and may be stored in a lookup table. 
     Next, the touch driving signals are generated (S 103 ). 
     The generating (S 103 ) of the touch driving signals includes generating the touch driving signals TX to which the voltage changes of the touch driving signals TX according to the frame frequencies are applied through the adjusting (S 102 ) of the touch driving signals, and may be performed by the touch driving signal generator  421  of touch driving signal unit  420 . Here, the touch driving signal TX may have a form of a sine wave. 
     Then, the driving signals are applied to the touch panel (S 104 ). 
     The touch driving signals TX to which phase changes of the touch driving signals according to the frame frequencies generated in the generating (S 103 ) of the touch driving signals are applied may be simultaneously supplied to the plurality of touch electrodes TE of the touch panel. 
     Referring to  FIG.  15   , the touch controller  410  according to embodiments receives the first frame frequency synchronization signal Hsync_f from the frame frequency synchronization signal controller  240  (S 201 ). 
     The touch controller  410  counts one cycle of an internal clock signal during a time section in which it receives the first frame frequency synchronization signal Hsync_f from the frame frequency synchronization signal controller  240  (S 202 ). 
     In addition, when the touch controller  410  receives a low-level counter enable signal from the frame frequency synchronization signal controller  240 , the touch controller  410  transfers a counted value of the internal clock signal counted during a time section in which it receives a high-level counter enable signal to the touch driving signal unit  420 . In some embodiments, the counted value of the internal clock signal may be written in a register of the touch controller  410  and be read by the touch driving signal unit  420  through an input/output interface with the touch controller  410 . 
     Then, the touch controller  410  calculates the frame frequency based on the counted value of the internal clock signal (S 203 ). 
     The calculated value may be input to the touch controller  410  by the frame frequency synchronization signal controller  240  through an input/output interface with the touch controller  410 . 
     The touch controller  410  changes a parameter of the touch driving signal according to the calculated value (S 204 ). 
     Changing the parameter may include adjusting voltages of the touch driving signals TX or adjusting capacitances of capacitors. It may also include adjusting sampling values in order to avoid the display noise (see  FIG.  13   ). However, the above-described parameter change is not necessarily limited thereto. 
     Therefore, even though the frame frequency at which the display driver  200  controls the display panel  100  varies, the touch controller  410  may accurately recognize the user’s touch input. Accordingly, even though the frame frequency varies, an influence of the display noise section  730   a  on the touch driving signals TX acting from the display panel  100  may be minimized. 
     In addition, distortion of the touch driving signals TX due to the data signals may be decreased, and distortion of an image quality may be minimized while maintaining reliability of touch sensitivity. 
       FIG.  16    is a timing diagram that illustrates a method of driving a display driver according to another embodiment. 
     A method of driving a display driver illustrated in  FIG.  16    is substantially similar to the method of driving the display driver illustrated in  FIG.  13    except that a duty value  720   b  of a porch section  710   b  is different from the duty value  720   a  of the porch section  710   a , and an overlapping description thereof will thus be omitted. 
     Referring to  FIG.  16   , a first touch driving signal T xlb  may be applied to the touch unit TSU in a section in which a frame frequency of a screen to be displayed on the display panel  100  is a second frame frequency  700   b . The first touch driving signal T xlb  may be based on a section in which the vertical synchronization signal Vsync and the second frame frequency synchronization signal Hsync_f are applied, e.g. the section which the frame frequency of the screen to be displayed on the display panel  100  is the second frame frequency  700   b . When the vertical synchronization signal Vsync and the second frame frequency synchronization signal Hsync_f corresponding to the second frame frequency  700   b  are received from the display driver  200 , the touch controller  410  included in the touch driver  400  may apply the first touch driving signal T xlb  to the touch unit TSU based on the section in which the synchronization signals are applied. 
     The duty value  720   b  of the second frame frequency synchronization signal Hsync_f may be a high section. The “high section” of the signal may refer to an interval of the signal with a relatively high value, e.g. an “on” value as opposed on an “off” value. For example, the second frame frequency synchronization signal Hsync_f is generated based on the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, and the frame frequency signal Sgn_f received from the display driver  200 . In this case, duty values of the vertical synchronization signal Vsync and the frame frequency synchronization signal Hsync_f correspond to the duty values corresponding to the frame frequencies stored in the memory. Accordingly, the second frame frequency synchronization signal Hsync_f having the high section according to the frame frequency is generated in the porch section  710   b  of the vertical synchronization signal Vsync. 
     When one pulse width of the vertical synchronization signal Hsync is 1 H, the duty value  720   b  may be greater than a pulse width of a plurality of vertical synchronization signals Hsync. For example, the duty value  720   b  may have a pulse width of at least 3 H to 4 H. 
     This timing is similar to  FIG.  13    in that the display driver  200  provides the vertical synchronization signal Vsync and the second frame frequency synchronization signal Hsync_f to the touch driver  400  and the touch driver  400  applies a second touch driving signal T x   2   b  to the touch unit TSU during a display noise section  730   b , and accordingly a description thereof will be omitted to avoid redundancy. 
     Also, in the embodiment, the frame frequency synchronization signal Hsync_f may be generated by setting a high section of the porch section  710   b  to the duty value  720   b , and may be provided to the touch driver  400 , and the touch driver  400  may receive the above-described signals and generate the touch driving signals TX in order to avoid the display noise according to a period in which the gate signals and the data signals are transmitted. 
     For example, even though the frame frequency at which the display driver  200  controls the display panel  100  varies, an influence of the display noise section  730   b  on the touch driving signals TX acting from the display panel  100  may be minimized, and the touch controller  410  may accurately recognize a user’s touch input. In addition, distortion of the touch driving signals TX due to the data signals may be decreased, and distortion of an image quality may be minimized while maintaining reliability of touch sensitivity. 
       FIG.  17    is a timing diagram that illustrates a method of driving a display driver according to still another embodiment. 
     A method of driving a display driver illustrated in  FIG.  17    is substantially similar to the method of driving the display driver illustrated in  FIG.  13    except that a duty value  720   b  of a porch section  710   b  is different from the duty value  720   a  of the porch section  710   a , and an overlapping description thereof will be omitted to avoid redundancy. 
     Referring to  FIG.  17   , a first touch driving signal T xlb  may be applied to the touch unit TSU in a section in which a frame frequency of a screen to be displayed on the display panel  100  is a second frame frequency  700   b . The first touch driving signal T xlb  may be based on a section in which the vertical synchronization signal Vsync and the second frame frequency synchronization signal Hsync_f are applied, e.g. the section which the frame frequency of the screen to be displayed on the display panel  100  is the second frame frequency  700   b . When the vertical synchronization signal Vsync and the second frame frequency synchronization signal Hsync_f corresponding to the second frame frequency  700   b  are received from the display driver  200 , the touch controller  410  included in the touch driver  400  may apply the first touch driving signal T xlb  to the touch unit TSU based on the section in which the synchronization signals are applied. 
     The duty value  720   b  of the second frame frequency synchronization signal Hsync_f may have at least one high section. For example, the duty value  720   b  may have a first high section  721  and a second high section  722 . 
     When one pulse width of the vertical synchronization signal Hsync is 1 H, the width of the first high section  721  and the second high section  722  of the duty value  720   b  may be greater than a pulse width of a plurality of vertical synchronization signals Hsync. For example, each of the first high section  721  and the second high section  722  of the duty value  720   b  may have a pulse width greater than a pulse width of at least 3 H to 4 H. 
     In addition, the first high section  721  and the second high section  722  may each have a pulse width at any point in time within the porch section  710   b . For example, the first high section  721  may have a predetermined high section after a section of 3 H to 4 H (pulse width of the vertical synchronization signal Hsync) elapses since the porch section  710   b  has started. In addition, the second high section  722  may have a predetermined high section at any point in time in the porch section  710   b . 
     However, when one pulse width of the vertical synchronization signal Hsync is 1 H, the duty value  720   b  may be greater than a pulse width of a plurality of vertical synchronization signals Hsync. For example, the duty value  720   b  may have a pulse width of at least 3 H to 4 H. 
     The duty value  720   b  may be the sum of a plurality of high sections. Accordingly, the second frame frequency synchronization signal Hsync_f having frame frequency information corresponding to the duty value  720   b  corresponding to the sum of the first high section  721  and the second high section  722  stored in the memory  245  may be output. 
     Accordingly, the second frame frequency synchronization signal Hsync_f having the duty value  720   b  stored in the memory is output based on the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, and the frame frequency signal Sgn_f received from the display driver  200 . Thereafter, similar to the method described with reference to  FIG.  13   , the display driver  200  provides the vertical synchronization signal Vsync and the second frame frequency synchronization signal Hsync_f to the touch driver  400  and the touch driver  400  applies a second touch driving signal T x   2   b  to the touch unit TSU during a display noise section  730   b . Accordingly, redundant description thereof will be omitted. 
     Also in the embodiment, the frame frequency synchronization signal Hsync_f may be generated by setting the duty value  720   b  having the plurality of high sections in the porch section  710   b  and be provided to the touch driver  400 , and the touch driver  400  may receive the above-described signals and generate the touch driving signals TX in order to avoid the display noise according to a period in which the gate signals and the data signals are transmitted. 
     For example, even though the frame frequency at which the display driver  200  controls the display panel  100  varies, an influence of the display noise section  730   b  on the touch driving signals TX acting from the display panel  100  may be minimized, and the touch controller  410  may accurately recognize a user’s touch input. In addition, distortion of the touch driving signals TX due to the data signals may be decreased, and distortion of an image quality may be minimized while maintaining reliability of touch sensitivity. 
       FIG.  18    is a block diagram that illustrates the display device according to an embodiment. Referring to  FIG.  18   , the display device  10  may include a display driver  200 , a memory unit  20 , a storage unit  30 , a processor  40 , an input/output unit  50 , and a power supply unit  60 . 
     The memory unit  20  may store data required for operations of the display device  10 . For example, the memory unit  20  may store the aforementioned present duty values. For example, the memory unit  20  may include a non-volatile memory device such as an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory, a phase change random access memory (PRAM), and a resistance random access memory (RRAM) or a volatile memory device such as a dynamic random access memory (DRAM) or a static random access memory (SRAM). 
     The storage unit  30  may include a solid state drive (SSD), a hard disk drive (HDD), a compact disk read-only memory (CD-ROM), and the like. 
     The processor  40  may perform a specific calculation or task. The processor  40  may be a microprocessor, a central processing unit (CPU), or the like. The processor  40  may be connected to other components through a bus or the like. The input/output unit  50  may include an input means such as a keyboard, a keypad, a touch pad, a touch screen, and a mouse, and an output means such as a speaker and a printer. The power supply unit  60  may supply power required for the operations of the display device  10 . 
     According to embodiments of the present disclosure, by changing a touch driving signal in response to a frame frequency input to a display driver, effects from noise of the display signals interacting with the touch driving signals may be mitigated, touch input reliability may be increased, and touch input sensitivity may be maintained. Further, visual artifacts produced by the display panel may be reduced. 
     In concluding the detailed description, those skilled in the art will appreciate that many variations and modifications can be made to the embodiments without substantially departing from the principles of the present inventive concept. Therefore, the disclosed embodiments of the inventive concept are used in a generic and descriptive sense only and not for purposes of limitation.