Patent Publication Number: US-2022216271-A1

Title: Touch display device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 16/726,609, filed on Dec. 24, 2019, which claims the priority benefit of Korean Patent Application No. 10-2018-0172867, filed on Dec. 28, 2018, which are hereby incorporated by reference in their entirety for all purposes as if full set forth herein. 
    
    
     BACKGROUND 
     Field of the Disclosure 
     The present disclosure relates to a touch display device. 
     Description of the Background 
     As the information society has developed at a rapid rate, there is an increasing need for display devices employing advanced technologies and more efficient methods. Recently, various types of display devices, such as a liquid crystal display (LCD) device, a plasma display panel (PDP) device, an organic light emitting display (OLED) device, or the like, have been developed and utilized. 
     Such display devices have been developed from typical input devices relying on a button, a keyboard, or a mouse, and provides a touch-based input interface that enables a user to easily input information or a command intuitively and conveniently. In order to provide a touch-based input interface by such a touch-based display device, it is necessary to detect the presence or absence of a user&#39;s touch on a display panel and detect correctly touch coordinates corresponding to the position of the touch on the display panel. There has been an increasing need for a capacitive sensing scheme enabling the presence or absence of a touch, touch coordinates, or the like to be detected based on a change in capacitance between touch electrodes or a change in capacitance between a touch electrode and a user associated medium (e.g., a stylus pen or part of a user&#39;s body), over the display panel of the display device including a plurality of touch electrodes (e.g., electrodes arranged in a row and electrodes arranged in a column). 
     A display device capable of providing a touch-based input interface may be referred to as a touch display device. As needed, a touch panel can be disposed in an area corresponding to the location of a display panel. This scenario enables the location of the touch panel to be understood intuitively, and display device to be operated according to a touch on an intuitive location, however, in case the touch panel is disposed on the display panel, the thickness of the display device is increased, and a process is needed for disposing the touch panel on the display panel. In addition, there is a problem in that such a touch panel causes increased power consumption of the display device. 
     SUMMARY 
     Accordingly, the present disclosure is directed to a touch display device that substantially obviates one or more problems due to limitations and disadvantages of the prior art. 
     More specifically, the present disclosure provides a touch display device capable of sensing a touch and being implemented in a thinner structure. 
     In addition, the present disclosure provides a touch display device capable of reducing power consumption. 
     In accordance with one aspect of the present disclosure, a touch display device is provided that includes: a substrate, a planarization film disposed over the substrate, an anode electrode and a touch metal disposed on the planarization film, a bank disposed over the planarization film on which the anode electrode and the touch metal are disposed, and including a first cavity exposing the anode electrode and a second cavity exposing the touch metal, an organic light emitting layer disposed in the first cavity and disposed over the anode electrode, and a cathode electrode disposed over the organic light emitting layer and the bank, wherein the cathode electrode includes a plurality of cathode electrodes separated from each other, and a part of at least one of the plurality of separated cathode electrodes is disposed in the second cavity and connected to the respective touch metal in the second cavity. 
     The touch display device may include a plurality of pixels, each of the plurality of pixels including: a first transistor for generating a first current in response to a data signal, a second transistor for transferring the data signal to the first transistor in response to a gate signal, a storage capacitor for holding the data signal transferred to the first transistor, and an organic light emitting diode for emitting light by the first current from the first transistor. In some aspects, the touch display device is configured to: transfer the data signal and the gate signal to a data line and a gate line, respectively, during a first interval, transfer a touch driving signal to the cathode electrode of the organic light emitting diode during a second interval, and during the second interval, transfer a load free driving signal in synchronism with the touch driving signal to at least one of the data line, the gate line, and a power supply line, in order to make a second current flow through the cathode electrode. 
     In accordance with aspects of the present disclosure, it is possible to provide a touch display device capable of sensing a touch and being implemented in a thinner structure. 
     In accordance with aspects of the present disclosure, it is possible to provide a touch display device capable of reducing power consumption. 
     Additional features and advantages of the disclosure will be set forth in the description which follows and in part will be apparent from the description, or may be learned by practice of the disclosure. The objectives and other advantages of the disclosure will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the present disclosure and which are incorporated in and constitute a part of the disclosure, illustrate aspects of the present disclosure and together with the description serve to explain the principles of the present disclosure. 
       In the drawings: 
         FIG. 1  is a diagram schematically illustrating a touch display device to which the present disclosure may be applied; 
         FIG. 2  is a cross-sectional diagram illustrating the display panel illustrated in  FIG. 1 ; 
         FIG. 3  is a diagram illustrating the touch sensor employed in the touch display device illustrated in  FIG. 1 ; 
         FIG. 4A  is a diagram illustrating an example of the touch electrode illustrated in  FIG. 3 ; 
         FIG. 4B  is a diagram illustrating another example of the touch electrode illustrated in  FIG. 3 ; 
         FIG. 5  is a circuit diagram illustrating the subpixel employed in the display panel illustrated in  FIG. 1 ; 
         FIG. 6  is a timing chart illustrating a method of driving the display panel illustrated in  FIG. 1 ; 
         FIG. 7  is a timing chart illustrating another method of driving the display panel illustrated in  FIG. 1 ; 
         FIG. 8  is a circuit diagram illustrating a connection between the touch circuit and the touch electrode illustrated in  FIG. 5 ; and 
         FIG. 9  is a graph illustrating the waveform of a signal applied to the touch circuit and the touch electrode illustrated in  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
     The advantages and features of the present disclosure and methods of achieving the same will be apparent by referring to aspects of the present disclosure as described below in detail in conjunction with the accompanying drawings. However, the present disclosure is not limited to the aspects set forth below, but may be implemented in various different forms. The following aspects are provided only to complete the present disclosure and inform those skilled in the art of the scope of the present disclosure, as defined by the appended claims. 
     In addition, the shapes, sizes, ratios, angles, numbers, and the like illustrated in the accompanying drawings for describing the exemplary aspects of the present disclosure are merely examples, and the present disclosure is not limited thereto. Like reference numerals generally denote like elements throughout the present specification. Further, in the following description of the present disclosure, detailed description of well-known functions and configurations incorporated herein will be omitted when it is determined that the description may make the subject matter in some aspects of the present disclosure rather unclear. The terms such as “including”, “having”, “containing”, “comprising of”, and “consist of” used herein are generally intended to allow other components to be added unless the terms are used with the term “only”. As used herein, singular forms are intended to include plural forms unless the context clearly indicates otherwise. 
     In interpreting any elements or features of the aspects of the present disclosure, it should be considered that any dimensions and relative sizes of layers, areas and regions include a tolerance or error range even when a specific description is not conducted. 
     Terms, such as first, second, A, B, (A), or (B) may be used herein to describe elements of the disclosure. Each of the terms is not used to define essence, order, sequence, or number of an element, but is used merely to distinguish the corresponding element from another element. When it is mentioned that an element is “connected” or “coupled” to another element, it should be interpreted that another element may be “interposed” between the elements or the elements may be “connected” or “coupled” to each other via another element as well as that one element is directly connected or coupled to another element. Spatially relative terms, such as, “on”, “over”, “above”, “below”, “under”, “beneath”, “lower”, “upper”, “near”, “close”, “adjacent”, and the like, may be used herein to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures, and it should be interpreted that one or more elements may be further “interposed” between the elements unless the terms such as “directly”, “only” are used. 
     Any elements or features of the aspects of the present disclosure are not limited to a specific meaning of the terms described above. The terms as used herein are merely for the purpose of describing examples and are not intended to limit the present disclosure. Although the terms “first”, “second”, and the like are used for describing various elements, or features, these elements are not confined by these terms. These terms are merely used for distinguishing one element from other elements. Therefore, a first element to be mentioned below may be a second element in a technical concept of the present disclosure. 
     The elements or features of various exemplary aspects of the present disclosure can be partially or entirely bonded to or combined with each other and can be interlocked and operated in technically various ways as can be fully understood by a person having ordinary skill in the art, and the various exemplary aspects can be carried out independently of or in association with each other. 
     Hereinafter, exemplary aspects of the present disclosure will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a diagram schematically illustrating a touch display device to which the present disclosure may be applied. 
     Referring to  FIG. 1 , the touch display device includes a display panel  110 , a data driver  130 , a gate driver  140 , a touch sensor  150 , and a controller  160 . 
     The display panel  110  can include a plurality of gate lines (GL 1 , . . . , GLn) and a plurality of data lines (DL 1 , . . . , DLm), which intersect each other at a predetermined angle. The display panel  110  can include a plurality of pixels  101  arranged to be corresponded to an area in which the plurality of gate lines (GL 1 , . . . , GLn) and the plurality of data lines (DL 1 , . . . , DLm) intersect each other. The plurality of pixels  101  can include a plurality of subpixels emitting light, such as red light, green light, blue light, white light, or the like. However, aspects of the present disclosure are not limited thereto. 
     Each of the plurality of subpixels can include an organic light emitting diode and a pixel circuit supplying a first current to the organic light emitting diode. The pixel circuit is connected to the plurality of gate lines (GL 1 , . . . , GLn) and the plurality of data lines (DL 1 , . . . , DLm), and can supply the first current to the organic light emitting diode. Lines disposed in the display panel  110  are not limited to the gate lines (GL 1 , . . . , GLn) and the data lines (DL 1 , . . . , DLm). 
     The data driver  130  can apply at least one data signal to the plurality of data lines (DL 1 , . . . , DLm). The data signal may correspond to gray scale, and a voltage level of a data signal may be determined depending on the corresponded gray scale. A voltage of the data signal may be referred to as a data voltage. 
     It is noted that a single data driver  130  is illustrated in  FIG. 1 , but aspects of the present disclosure are not limited thereto. The number of data drivers may be determined depending on the size or resolution of the display panel  110 . In addition, the data driver  130  may be implemented as an integrated circuit. 
     The gate driver  140  can apply at least one gate signal to the plurality of gate lines (GL 1 , . . . , DLm). At least one pixel  101  corresponding to the plurality of gate lines (GL 1 , . . . , GLn) to which the at least one gate signal is applied can received the at least one data signal. Further, the gate driver  140  can transfer a sensing signal to at least one pixel  101 . The pixel  101  received the sensing signal outputted from the gate driver  140  can receive a sensing voltage outputted from the data driver  130 . It is noted that a single gate driver  140  is illustrated in  FIG. 1 , but aspects of the present disclosure are not limited thereto. The number of gate drives may be at least two gate drives. Further, the gate driver  140  can include two gate drivers disposed on both sides of the display panel  110 , and one can be connected to one or more odd numbered gate lines of the plurality of gate lines (GL 1 , . . . , GLn) and the other can be connected to one or more even numbered gate lines of the plurality of gate lines (GL 1 , . . . , GLn). However, aspects of the present disclosure are not limited thereto. 
     The gate driver  140  may be implemented as an integrated circuit. Further, the gate driver  140  can include a gate signal generating circuit, and a level shifter for applying a signal and/or a voltage to the gate signal generating circuit. The gate signal generating circuit can be disposed on the display panel  110 . 
     The touch sensor  150  can output a touch sensing signal in response to a touch on the display panel  110 . Herein, the touch can include, the contact of a touch object, such as a stylus pen or part of a user&#39;s body, with the display panel  110 , as well as the approach of the touch object to the display panel  110  within a certain distance. The touch sensor  150  can include a plurality of touch electrodes, and a touch circuit processing a touch signal associated with the touch electrodes. The touch signal may be a touch driving signal and a touch sensing signal. The touch circuit can receive a touch sensing signal in response to a touch driving signal applied to the touch electrode, and output a voltage or current corresponding to the touch sensing signal. 
     The touch sensor  150  can include at least one touch line connecting between at least one touch electrode and the touch circuit, The touch sensor  150  can sense a change in a voltage charged to the touch electrode, and output a signal corresponding to the charged voltage. The touch sensor  150  can cause the touch electrode to receive a touch driving signal, charge a certain voltage, and output a touch sensing signal corresponding to the charged voltage. The touch circuit may be implemented as an integrated circuit. 
     The controller  160  can control the touch sensor  150 . The controller  160  can supply a touch driving signal to the touch sensor  150 , and can detect the location of a corresponding touch based on a touch sensing signal in response to the supplied touch driving signal. The controller  160  can control the data driver  130  and the gate driver  140 . The controller  160  can transfer an image signal corresponding to a data signal to the data driver  130 . The image signal may be a digital signal. The controller  160  can correct the image signal and then transfer the corrected image signal to the data driver  130 . Herein, operations of the controller  160  are not limited thereto. The controller  160  can include the touch circuit. The controller  160  can include a timing controller. The touch circuit can control the touch sensor, and the timing controller can control the data driver  130  and the gate driver  140 . Herein, configurations of the controller  160  of the present disclosure are not limited thereto. The controller  160  may be implemented as an integrated circuit. 
       FIG. 2  is a cross-sectional diagram illustrating the display panel illustrated in  FIG. 1 . 
     Referring to  FIG. 2 , the display panel  110  can include a substrate  111 , a planarization film  120  disposed over the substrate  111 , an anode electrode  121   a  and a touch metal  121   b  disposed on the planarization film  120 , a bank  122  disposed over the planarization film on which the anode electrode  121   a  and the touch metal  121   b  are disposed, an organic light emitting layer  124  disposed over the anode electrode  121   a,  and a cathode electrode  125  disposed over the organic light emitting layer  124  and the bank  122 . 
     The substrate  111  may include poly amide and/or polyethylene terephthalate (PET). The substrate  111  can include glass. However, aspects of the present disclosure are not limited thereto. A buffer layer  112  can be disposed on the substrate  111 . An active layer  113  can be disposed on the buffer layer  112 . The active layer  113  may be low temperature poly silicon. The active layer  113  may be an oxide semiconductor. However, aspects of the present disclosure are not limited thereto. A gate insulating film  114  can be disposed over the substrate  111  including the active layer  113 . A first gate electrode  115   a  and a second gate electrode  115   b  can be formed by patterning after a gate metal has been disposed on the gate insulating film  114 . The first gate electrode  115   a  can be disposed to overlap the active layer  113  on the gate insulating film  114 . A first interlayer insulating film  116  can be disposed on the gate insulating film  114  on which the first gate electrode  115   a  and the second gate electrode  115   b  are disposed. 
     A conducting layer  117  can be patterned and disposed on the first interlayer insulating film  116 . The conducting layer  117  can be disposed to overlap the second gate electrode  115   b.  A capacitor may be disposed over the substrate  111  by the conducting layer  117  and the second gate electrode  115   b.  A second interlayer insulating film  118  can be disposed on the first interlayer insulating film  116 , and at least one contact hole can be formed in the first interlayer insulating film  116  and the second interlayer insulating film  118 . The active layer  113  can be exposed through the contact hole. A source/drain metal is disposed and patterned on the conducting layer  117 , and thus a source electrode  119   a  and a drain electrode  119   b  can be disposed thereon. The source electrode  119   a  and the drain electrode  119   b  can be contacted the active layer  113  through respective contact holes. A planarization film  120  can be disposed on the conducting layer  117  on which the source electrode  119   a  and the drain electrode  119   b  are disposed. A contact hole can be formed in the planarization film  120 . The drain electrode  119   b  can be exposed through the contact hole. 
     An anode metal can be disposed and patterned on the planarization film  120 . The anode electrode  121   a  and the touch metal  121   b  can be disposed on the planarization film  120  by the patterned anode metal. The anode electrode  121   a  can contact the drain electrode  119   b  through the contact hole. The bank  122  can be disposed over the planarization film  120  on which the anode electrode  121   a  and the touch metal  121   b  are disposed. A first cavity CA 1  and a second cavity CA 2  can be disposed in the bank  122 , and the anode electrode  121   a  can be exposed through the first cavity CA 1  and the touch metal  121   b  can be exposed through the second cavity CA 2 . One or more spacers  123   a  and  123   b  with a predetermined height can be disposed on the bank  122 . The cross-section of the spacers  123   a  and  123   b  may have a shape tapering toward the bank  122 . Herein, the shape of the spacers  123   a  and  123   b  is not limited thereto. 
     The first spacer  123   a  can be a spacer disposed adjacent to the second cavity CA 2 , and the second spacer  123   b  can be a spacer spaced apart from the second cavity CA 2 . An organic light emitting layer  124  can be disposed over the anode electrode  121   a.  The organic light emitting layer  124  can be formed of a plurality of stacked layers. One or more of the plurality of layers of the organic light emitting layer  124  can be disposed over the anode electrode  121   a.  In some aspects, the one or more of the plurality of layers can be disposed only over the anode electrode  121   a.  As another example, all the organic light emitting layer  124  can be disposed over the anode electrode  121   a.  However, aspects of the present disclosure are not limited thereto. The cathode electrode  125  can be disposed over the organic light emitting layer  124 . 
     The organic light emitting layer  124  and the cathode electrode  125  can be disposed over the spacers  123   a  and  123   b  because upper portions of the spacers  123   a  and  123   b  have a predetermined width. On the other hand, the organic light emitting layer  124  and the cathode electrode  125  may not be disposed in areas in which the spacers  123   a  and  123   b  are disposed. In addition, since the spacers  123   a  and  123   b  have a predetermined height, the organic light emitting layer  124  and the cathode electrode  125  disposed over the bank  122  cannot be connected to the organic light emitting layer  124  and the cathode electrode  125  disposed over the spacers  123   a  and  123   b,  respectively. The cathode electrode  125  can be disposed to be divided into a plurality of cathode electrodes  125   a,    125   b  and  125   c.  Accordingly, the cathode electrode  125  can be divided into a first cathode electrode  125   a,  a second cathode electrode  125   b,  and a third cathode electrode  125   c,  which are disposed over the bank  122  and spaced apart from one another. 
     The first cathode electrode  125   a  can be connected to the touch metal  121   b  in the second cavity CA 2 . The second cathode electrode  125   b  can be connected to another touch metal in another second cavity (not shown) Accordingly, the first cathode electrode  125   a  and the second cathode electrode  125   b  can receive respective touch signals from respective touch metals. The third cathode electrode  125   c  can be connected to yet another touch metal in yet another second cavity (not shown) Accordingly, the third cathode electrode  125   c  can receive respective touch signals from respective touch metals. The touch metal  121   b  can be included in a touch electrode line TEL to which a touch signal is transferred as illustrated in  FIG. 3 . 
     An encapsulation  126  can be disposed on the cathode electrode  125 . However, aspects of the present disclosure are not limited thereto. The encapsulation  126  can be disposed on one or more side portions of the substrate  111 , thus can seal elements and electrodes disposed over the substrate  111 . The encapsulation  126  can include an organic film layer  126   a  and an inorganic film layer  126   b.  The encapsulation  126  cannot be disposed at least an area of the substrate  111 . At least one pad delivering for a signal and/or a voltage can be disposed in the area in which the encapsulation  126  is not disposed. 
     Since the cathode electrode  125  is connected to the touch metal and used as the touch electrode, and a separate layer for sensing a touch over the substrate  111  is not required, therefore, it is possible to prevent the width of the display panel  110  from being greater. In addition, since the touch metal and the touch electrode are formed during the process of manufacturing display panel  110 , an aligning process is not required and therefore it is possible to prevent related manufacturing process from being complicated even when the touch electrode is disposed on the display panel  110 . 
       FIG. 3  is a diagram illustrating the touch sensor employed in the touch display device illustrated in  FIG. 1 . 
     Referring to  FIG. 3 , a plurality of touch electrodes TE, and a plurality of touch electrode lines TEL connected to each touch electrode TE are disposed on the display panel  110 . The plurality of touch electrodes TE can be disposed to be spaced apart from one another. Here, in  FIG. 3 , the plurality of touch electrodes TE are disposed such that  16  touch electrodes are disposed in a matrix form of 4*4, but aspects of the present disclosure are not limited thereto. Each of the plurality of touch electrode lines TEL can extend in a first direction. The first touch electrode TE 1  can correspond to the first cathode electrode  125   a  illustrated in  FIG. 2 , and the third touch electrode TE 3  spaced apart from the first touch electrode TE 1  can correspond to the third cathode electrode  125   c  illustrated in  FIG. 2 . Each touch electrode TE can be connected to a different touch electrode line TEL from one another. Here, in  FIG. 3 , one touch electrode line TEL contacts one touch electrode TE at two points Ct 1  and Ct 2 , but aspects of the present disclosure are not limited thereto. One touch electrode line TEL can be contacted one touch electrode TE at one point Ct 1  or at two or more points. The two points Ct 1  and Ct 2  may be points at which the touch metal  121   b  illustrated in  FIG. 2  is connected to the touch electrode TE. The spacer illustrated in  FIG. 2  can be disposed between the touch electrodes TE. That is, the spacer can be disposed in an area SA in which the touch electrode TE is not disposed. Accordingly, the area SA in which the touch electrode TE is not disposed can extend in a first direction and in a second direction, between the touch electrodes TE. Further, a plurality of pixels  101  can correspond to one touch electrode TE. That is, a plurality of organic light emitting diodes can be disposed under one touch electrode TE. 
       FIG. 4A  is a diagram illustrating an example of the touch electrode illustrated in  FIG. 3 , and  FIG. 4B  is a diagram illustrating another example of the touch electrode illustrated in  FIG. 3 . 
     Referring to  FIG. 4A , the first cathode electrode  125   a  can be disposed to be corresponded to one first touch electrode TE 1 . That is, the first cathode electrode  125   a  illustrated in  FIG. 2  can correspond to the first touch electrode TE 1 . In addition, each of a plurality of boxes  401  represented by dotted lines in the first cathode electrode TE 1  can correspond to each pixel  101 . Accordingly, the plurality of pixels  101  can be corresponded to the first cathode electrode  125   a.  In addition, the first cathode electrode  125   a  is formed of one electrode body corresponding to the plurality of pixels  101 ; therefore can function as both a cathode electrode and a touch electrode being corresponded to the plurality of pixels  101 . 
     Referring to  FIG. 4B , the first touch electrode TE 1  can include a plurality of divided cathode electrodes  410  to  490  disposed in pixel areas. The plurality of divided cathode electrodes  410  to  490  disposed in the pixel areas can correspond to the first cathode electrode  125   a  illustrated in  FIG. 2 . One of the divided cathode electrodes  410  to  490  can directly contact the touch metal  121   b.  Further, a part of the one of the divided cathode electrodes  410  to  490  disposed in the pixel areas can be connected to a part of another one of the divided cathode electrodes  410  to  490  through a connection electrode AR. Here, the connection electrode AR can be formed of the same material as the cathode electrode. Further, each of the plurality of divided cathode electrodes  410  to  490  disposed in the pixel areas can correspond to one pixel  101 . However, aspects of the present disclosure are not limited thereto. Accordingly, each of the plurality of divided cathode electrodes  410  to  490  disposed in the pixel areas may correspond to a plurality of pixels. In addition, another spacer can be disposed between the plurality of divided cathode electrodes  410  to  490  disposed in the pixel areas, which correspond to one touch electrode TE. A spacer may not be disposed in an area in which the connection electrode AR is disposed. 
     Further, the divided cathode electrodes  410  to  490  disposed in the pixel areas can be transparent electrodes. Further, the divided cathode electrodes  410  to  490  disposed in the pixel areas can be in the form of a mesh. 
       FIG. 5  is a circuit diagram illustrating the pixel employed in the display panel illustrated in  FIG. 1 . 
     Referring to  FIG. 5 , the pixel  101  can include: a first transistor M 1  generating a first current in response to a data signal Vdata, a second transistor M 2  transferring a data signal Vdata to the first transistor M 1  in response to a gate signal, a storage capacitor Cst holding the data signal Vdata transferred to the first transistor M 1 , and an organic light emitting diode OLED emitting light by the first current received from the first transistor M 1 . 
     The gate electrode of the first transistor M 1  can be connected to a first node N 1 , and a first electrode thereof can be connected to a first power supply line VL to which a first power supply EVDD is supplied, and a second electrode thereof can be connected to a second node N 2 . The first electrode can be the source electrode illustrated in  FIG. 2 , the second electrode can be the drain electrode illustrated in  FIG. 2 . However, aspects of the present disclosure are not limited thereto. A magnitude of the first current can be determined corresponding to a voltage difference between the gate electrode and the second electrode of the first transistor M 1 . 
     The gate electrode of the second transistor M 2  can be connected to a gate line GL, and first and second electrodes thereof can be connected to a data line DL and the first node N 1 , respectively. Accordingly, a data signal flowing through the data line DL can be transferred to the first node N 1  in response to a gate signal transferred through the gate line GL 
     First and second electrodes of the storage capacitor Cst can be connected to the first and second nodes N 1  and N 2 , respectively. The storage capacitor Cst can hold a voltage between the first node N 1  and the second node N 2 . Accordingly, a voltage difference between the gate electrode and the second electrode of the first transistor M 1  can be held during a certain interval, and the first current can therefore flow constantly. 
     The organic light emitting diode OLED can emit light depending on a current supplied to the second node N 2 . The cathode electrode of the organic light emitting diode OLED can correspond to the cathode electrode  125   a,    125   b,    125   c  illustrated in  FIG. 2 . 
     The touch circuit  145  can be connected to the cathode electrode of the organic light emitting diode OLED. The touch circuit  145  can detect the presence or non-presence of a touch using a magnitude of a current flowing corresponding to a magnitude of a resistance R connected between the cathode electrode of the organic light emitting diode and a second power supply EVSS. 
       FIG. 6  is a timing chart illustrating a method of driving the display panel illustrated in  FIG. 1 , and  FIG. 7  is a timing chart illustrating another method of driving the display panel illustrated in  FIG. 1 . 
     A synchronization signal Tsync can repeat a high state and a low state. During an interval in which the synchronization signal Tsync is in the low state, the display panel  110  can operates as a display interval, and during an interval in which the synchronization signal Tsync is in the high state, the display panel  110  can operates as a touch interval. 
     Referring to  FIG. 6 , during a period of a frame, the synchronization signal Tsync can be divided into a first interval T 1   a  corresponding to the interval in the low state and a second interval T 2   a  corresponding to the interval in the high state. However, aspects of the present disclosure are not limited thereto. The first interval T 1   a  and the second interval T 2   a  can have an identical length, but aspects of the present disclosure are not limited thereto. In addition, the second interval T 2   a  can correspond to a vertical blank interval. The vertical blank interval may be an interval during which a vertical synchronizing signal is input, or may be an interval between one frame and the next frame. 
     In the first interval T 1   a , a data signal and a gate signal can be transferred to the data line DL and the gate line GL, respectively. Accordingly, the pixel  101  illustrated in  FIG. 5  can supply the first current to the organic light emitting diode OLED in response to the data signal, and then the organic light emitting diode OLED can emit light in response to the first current. In the first interval T 1   a , DC voltages with predetermined values can be supplied from the first power supply EVDD and the second power supply EVSS. A voltage level of the first power supply EVDD may be greater than that of the second power supply EVSS. For example, the voltage level of the first power supply EVDD may be 24V, and the voltage level of the second power supply EVSS may be 0V. However, aspects of the present disclosure are not limited thereto. 
     In the second interval T 2   a,  a voltage corresponding to a touch driving signal TDS can be transferred to the cathode electrode of the organic light emitting diode OLED. The touch driving signal TDS can include a plurality of pulses. Further, a load free driving signal LFD in synchronism with the touch driving signal TDS may be transferred to the first power supply EVDD. In addition, the load free driving signal LFD may be transferred to a gate line GL and a data line DL. When the load free driving signal LFD is not transferred, since a voltage level in the cathode electrode to which the touch driving signal TDS is transferred has differences from a voltage of the first power supply line VL, a voltage level charged in the gate line GL and a voltage level charged in the data line DL, therefore capacitances can be formed between the cathode electrode and the first power supply line VL, the gate line GL and the data line DL. This causes power consumption of the touch display device  100  to be increased. On the other hand, when the load free driving signal LFD in synchronism with the touch driving signal TDS is applied to the first power supply line VL, the gate line GL and the data line DL, it is possible to prevent such a capacitance from being formed; therefore, it is possible to reduce the power consumption of the touch display device  100 . The lines to which the load free driving signal LFD is applied in the display panel  110  are not limited to the first power supply VL, the gate line GL, and the data line DL. 
     Referring to  FIG. 7 , one frame period can be divided into a first interval T 1   b , a second interval T 2   b,  a third interval T 3   b,  and a fourth interval T 4   b.  In the first interval T 1   b  and the third interval T 3   b,  the synchronization signal Tsync can be in the low state, and in the second interval T 2   b  and the forth interval T 4   b,  the synchronization signal Tsync can be in the high state. However, aspects of the present disclosure are not limited thereto. Here, all of the first interval to the fourth interval T 1   b  to T 4   b  can have an identical interval, as in  FIG. 7 , but aspects of the present disclosure are not limited thereto. Each of the first interval to the fourth interval T 1   b  to T 4   b  may have a different length from one another. In addition, the second interval T 2   b  and the fourth interval T 4   b  can correspond to a vertical blank interval. The vertical blank interval may be an interval during which a vertical synchronizing signal is input, or may be an interval between one row and the next row of a plurality of rows of one frame. In addition, the second interval T 2   b  and the fourth interval T 4   b  can correspond to a long horizontal blank (LAB). 16 long horizontal blanks LAB may be disposed in one frame period. However, aspects of the present disclosure are not limited thereto. 
     In the first interval T 1   b  and the third interval T 3   b,  a data signal and a gate signal can be transferred to the data line DL and the gate line GL, respectively. Accordingly, the pixel  101  illustrated in  FIG. 5  can supply the first current to the organic light emitting diode OLED in response to the data signal, and then the organic light emitting diode OLED can emit light in response to the first current. In the first interval T 1   b , DC voltages with predetermined values can be supplied from the first power supply EVDD and the second power supply EVSS. A voltage level of the first power supply EVDD may be greater than that of the second power supply EVSS. For example, the voltage level of the first power supply EVDD may be 24V, and the voltage level of the second power supply EVSS may be 0V. However, aspects of the present disclosure are not limited thereto. 
     In the second interval T 2   b  and the fourth interval T 4   b,  the touch display device can sequentially apply one or more touch driving signals through a touch electrode line TEL corresponding to each of a plurality of cathode electrodes which are electrically separated from one another of the organic light emitting diode OLED, and thus can sense the presence of a touch on the display panel. At this time, a load free driving signal LFD may be applied to cathode electrodes which do not perform sensing. The load free driving signal and the touch driving signal are signals in synchronism with each other, and can be configured with an identical amplitude. Further, a load free driving signal LFD in synchronism with the touch driving signal TDS may be transferred to the first power supply EVDD. In addition, the load free driving signal LFD may be transferred to a gate line GL and a data line DL. The lines to which the load free driving signal LFD is applied in the display panel  110  are not limited thereto. 
       FIG. 8  is a circuit diagram illustrating a connection between the touch circuit and the touch electrode illustrated in  FIG. 5 , and  FIG. 9  is a graph illustrating the waveform of a signal applied to the touch circuit and the touch electrode illustrated in  FIG. 8 . 
     Referring to  FIGS. 8 and 9 , the touch circuit  145  can include an integrator  146  and a buffer  147 . The integrator  146  can calculate a magnitude of a voltage charged in each cathode electrode in response to voltages corresponding to currents flowing by voltages charged in cathode electrodes  125   a,    125   b,  and  125   c  which are electrically disconnected and a pre-set voltage. The buffer  147  can improve the characteristics of a voltage output from the integrator  146 . The buffer  147  can include a first inverter  147   a  and a second inverter  147   b.  However, aspects of the present disclosure are not limited thereto. 
     The touch circuit  145  can be connected to a power supply line connected to the second power supply EVSS. The touch circuit  145  can be connected to the cathode electrode of the organic light emitting diode OLED through a touch line TEL. The organic light emitting diode OLED can be connected to a pixel circuit  1011  generating a first current. Here, R_Tr(drv) represents a resistance corresponding to the first transistor M 1  in  FIG. 5 . A touch capacitor Cf formed by a touch can be connected to the cathode electrode. In addition, a signal applying unit  148  for applying a voltage corresponding to the load free driving signal LFD can be disposed in the cathode electrode. 
     Here, the load free driving signal LFD is not applied to the first power supply line VL for supplying the first power supply EVDD, the data line DL, and the gate line GL, and a load free driving signal LFD is applied by the signal applying unit  148  to the touch capacitor Cf instead of supplying a touch driving signal TDS to the cathode electrode. A magnitude of the touch capacitor Cf is represented by 1 pF or 0.5 pF. That is, it can be seen that a magnitude of the output voltage of the touch circuit is different depending on the magnitude of the touch capacitor Cf. Accordingly, it can be seen that a touch can be detected using changes in capacitance caused by a touch. 
     The disclosure is not limited to the specific features, structures, configurations, and effects described in the present disclosure. A person skilled in the art can apply the features, structures, configurations, and effects illustrated above to other aspects by combining or modifying such features, structures, configurations, and effects. The scope of protection should be construed based on the following claims.