Patent Publication Number: US-11656729-B2

Title: Touch sensor controller, operating method of touch sensor controller, and touch screen driving circuit

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2021-0016284, filed on Feb. 4, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Field 
     Embodiments relate to a touch sensor controller, an operating method of a touch sensor controller, and a touch screen driving circuit. 
     2. Description of the Related Art 
     A touch screen may include a display panel for displaying images and a touch sensor for sensing a touch, wherein the display panel and the touch sensor may be vertically stacked or may be integrally formed to share at least one layer. 
     SUMMARY 
     Embodiments are directed to a touch sensor controller for driving a touch sensor that is stacked on a display panel and includes driving electrodes and receiving electrodes crossing the driving electrodes, the touch sensor controller including: a driving circuit configured to sequentially provide driving signals to the driving electrodes; a read-out circuit configured to, in response to the driving signals, generate touch data based on first sensing signals received from the receiving electrodes and generate display noise data based on a second sensing signal received from a first driving electrode to which a driving signal of the driving signals is not applied from among the driving electrodes; and a touch processor configured to determine whether a touch input has occurred on the touch sensor based on the touch data and the display noise data. 
     Embodiments are also directed to an operating method of a touch sensor controller for driving a touch sensor that is stacked on a display panel and includes driving electrodes and receiving electrodes crossing the driving electrodes, the operating method including: applying a driving signal to at least one driving electrode from among the driving electrodes; performing, by first receivers provided in the touch sensor controller, touch sensing; and performing, by at least one second receiver provided in the touch sensor controller, display noise sensing simultaneously as the touch sensing is performed. 
     Embodiments are also directed to an operating method of a touch sensor controller for driving a touch sensor stacked on a display panel, the operating method including: generating, by the touch sensor controller, display noise data by performing display noise sensing during a first period of a display period in which an image is displayed on the display panel; generating, by the touch sensor controller, touch data by performing touch sensing in a second period during the display period, the second period being different from the first period; and processing, by the touch sensor controller, the touch data based on the display noise data. 
     Embodiments are also directed to a touch screen driving circuit for driving a touch screen panel including a display panel and a touch sensor stacked on the display panel, the touch screen driving circuit including: a display driving circuit configured to calculate a change amount of a power voltage at locations of the display panel based on received image data, and generate compensation information based on the change amount of the power voltage; and a touch sensor controller configured to receive the compensation information from the display driving circuit, and compensate for touch data generated based on touch sensing values received from the touch sensor based on the compensation information. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features will become apparent to those of skill in the art by describing in detail example embodiments with reference to the attached drawings in which: 
         FIG.  1    is a block diagram showing a touch screen device according to an example embodiment; 
         FIG.  2    is a diagram schematically showing a touch sensor controller according to an example embodiment; 
         FIG.  3    is a diagram for describing components of display noise introduced into a touch sensor stacked on a display panel; 
         FIG.  4    is a diagram showing a display noise sensing method according to an example embodiment; 
         FIGS.  5 A and  5 B  are timing diagrams showing an operating method of a touch sensor controller according to an example embodiment; 
         FIG.  6    is a diagram showing a display noise sensing method according to an example embodiment; 
         FIG.  7    is a diagram showing a positive driving signal and a negative driving signal of  FIG.  6   ; 
         FIG.  8    is a flowchart of an operating method of a touch sensor controller according to an example embodiment; 
         FIG.  9    is a block diagram schematically showing a touch sensor controller according to an example embodiment; 
         FIG.  10    is a diagram schematically showing operations of a read-out circuit and a read-out circuit according to an example embodiment; 
         FIG.  11    is a diagram schematically showing operations of a read-out circuit and a read-out circuit according to an example embodiment; 
         FIG.  12    is a flowchart of an operating method of a touch sensor controller according to an example embodiment; 
         FIG.  13    is a block diagram schematically showing a touch screen driving circuit according to an example embodiment; 
         FIG.  14    is a flowchart showing operations of a touch sensor controller and a display driving circuit provided in the touch screen driving circuit of  FIG.  13   ; 
         FIG.  15    is a flowchart of a method of generating a coupling voltage map according to an example embodiment; 
         FIG.  16    is a diagram showing a structure of a power line of a display panel; 
         FIG.  17    is a modeling diagram showing an internal structure of a display panel; 
         FIG.  18    is a graph showing a power voltage decreased in one column of a display panel; 
         FIG.  19    is a block diagram schematically showing a touch screen driving circuit according to an example embodiment; 
         FIG.  20    is a flowchart of an operating method of a touch sensor controller according to an example embodiment; and 
         FIGS.  21  and  22    are diagrams showing implementation examples of a touch screen driving circuit according to an example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    is a block diagram showing a touch screen device according to an example embodiment. 
     Referring to  FIG.  1   , a touch screen device  1000  may be mounted on various electronic devices. For example, the touch screen device  1000  may be mounted on an electronic device like a tablet personal computer (PC), an e-reader, a personal digital assistant (PDA), a portable multimedia player (PMP), a mobile terminal, a smartphone, a wearable device, an Internet of Things (IoT) device, a refrigerator, a navigation device, etc. Also, the touch screen device  1000  may be mounted on an electronic device provided as a component for vehicles, furniture, manufacturing facilities, doors, and various measuring devices. 
     Referring to  FIG.  1   , the touch screen device  1000  may include a touch screen  100  and a touch screen driving circuit  200  for driving the touch screen  100 . The touch screen  100  may include a touch sensor  110  and a display panel  120  to respectively provide a touch sensing function and a display function. The touch screen driving circuit  200  may include a touch sensor controller (TSC)  210  and a display driving circuit (DDI)  220 . The TSC  210  and the DDI  220  may be integrated on one semiconductor chip or may be separately implemented on a plurality of semiconductor chips. In another implementation, the TSC  210  and the DDI  220  may be implemented as one semiconductor module. 
     Although  FIG.  1    shows that the touch screen device  1000  includes a host  300 , the host  300  may be implemented separately from the touch screen device  1000 . 
     The touch screen  100  may display an image and may receive a touch input of a user. The touch screen  100  may operate as an input/output device of an electronic device, and may operate as a proximity sensor that senses an approach of a conductive object. In an example embodiment, the touch screen  100  may further include a fingerprint sensor, and the touch screen device  1000  may perform a fingerprint recognition function. 
     The touch sensor  110  may sense a touch (or a touch input) on the touch screen  100 , may and output sensing signals. Here, the touch includes not only a direct contact of a conductive object on the touch screen  100 , but also an approach of a conductive object to the touch screen  100 . For example, the conductive object may include a user&#39;s body part (e.g., a finger, a palm, the face, an ear), a touch pen, a stylus pen, etc. The touch sensor  110  may be stacked on the display panel  120 , and may be attached to a front surface of the display panel  120  (e.g., a surface from which light signals are emitted). In an example embodiment, the touch sensor  110  may cover the front surface of the display panel  120 . 
     The touch sensor  110  may be implemented as a transparent panel having a touch-sensitive surface. In another implementation, the touch sensor  110  may be implemented as a touch sensor array in which transparent electrodes are patterned. 
     The touch sensor  110  may include a plurality of electrodes. Sensing signals according to one of various touch sensing methods may be output through the electrodes. 
     In one example, the electrodes may respectively output sensing signals according to a capacitance sensing method. For example, the touch sensor  110  may include a driving electrode to which a driving signal Stx is applied, and a receiving electrode from which a sensing signal Ssen is output. The driving electrode may extend in a first direction, and the receiving electrode may extend in a second direction perpendicular to the first direction. The driving electrode and the receiving electrode may be referred to as a driving channel and a receiving channel, respectively. The touch sensor  110  may include a plurality of driving electrodes arranged side by side and a plurality of receiving electrodes arranged side by side. The driving electrode and the receiving electrode may cross each other, and a mutual capacitance may be formed between the driving electrode and the receiving electrode crossing each other. Each point at which mutual capacitance is formed may be referred to as a sensing node of the touch sensor  110 . 
     In another example, the touch sensor  110  may include a plurality of sensing electrodes arranged in rows and columns, and a capacitance may be formed in each of the sensing electrodes. For example, a capacitance may be formed between each sensing electrode and the ground (or a conductive layer in the touch screen  100 ), and the capacitance may be referred to as self-capacitance. A driving signal Stx may be applied to each of the sensing electrodes, and a sensing signal Ssen may be output from each of the sensing electrodes. Thus, each of the sensing electrodes may operate as a driving electrode and a receiving electrode, and each of the sensing electrodes may be referred to as a sensing node of the touch sensor  110 . The driving signal Stx may be applied through a driving electrode, and the sensing signal Ssen representing a capacitance (e.g., mutual capacitance or self-capacitance) may be generated based on the driving signal Stx, and the sensing signal Ssen may be output through a receiving electrode. When a conductive object like a human finger or a stylus contacts or is located close to a sensing node of the touch sensor  110 , the capacitance corresponding to the sensing node changes, and a sensing signal Ssen output from the touch sensor  110  may be changed according to the changed capacitance. For example, the level of the sensing signal Ssen may increase or decrease as compared to that before a touch occurs. Touch data may be generated based on levels of sensing signals Ssen output from the touch sensor  110 . 
     The display panel  120  may include a plurality of gate lines, a plurality of source lines, and a plurality of pixels respectively arranged in rows and columns at points where the gate lines intersect with the source lines. The pixels may display an image based on image signals Simg received through the source lines and the gate lines. The image may be updated according to a set frame rate. The display panel  120  may be implemented as one of a liquid crystal display (LCD), a light-emitting diode (LED) display, an organic LED (OLED) display, an active-matrix OLED (AMOLED) display, an electrochromic display (ECD), a digital mirror device (DMD), an actuated mirror device (AMD), a grating light valve (GLV), a plasma display panel (PDP), an electro luminescent display (ELD), a vacuum fluorescent display (VFD), and other types of flat panels or flexible panels. 
     Although  FIG.  1    shows that the touch sensor  110  and the display panel  120  are separate components, the touch screen  100  may be implemented as an in-cell type panel (in which electrodes of the touch sensor  110  and pixels of the display panel  120  are combined with each other) or an on-cell type panel (in which electrodes of the touch sensor  110  are arranged on the display panel  120 ). 
     The TSC  210  may scan (e.g., drive and sense) the touch sensor  110 . Thus, the TSC  210  may perform touch sensing. The TSC  210  may provide a driving signal Stx to the driving electrodes of the touch sensor  110 , and may receive sensing signals Ssen generated based on the driving signal Stx from the touch sensor  110 . 
     The TSC  210  may convert the sensing signals Ssen, which are analog signals, into touch values, which are digital signals, and may generate touch data including touch values corresponding to the respective sensing nodes of the touch sensor  110 . 
     The TSC  210  may determine that a touch input has occurred at at least one particular location on the touch screen  100  based on the touch data, and may calculate the location where the touch input has occurred, that is, a touch coordinate Txy. The TSC  210  may transmit the touch coordinate Txy to the host  300 . In an example embodiment, the TSC  210  may calculate a touch pressure, and may provide the touch pressure to the host  300  together with the touch coordinate Txy. 
     The TSC  210  may also determine that a conductive object is close to the touch screen  100  based on the touch data. Thus, the TSC  210  may perform proximity sensing. For example, when it is determined that a low-level touch input has occurred in a relatively wide region of the touch screen  100  based on the touch data, the TSC  210  may determine that a conductive object is close to the touch screen  100 . The TSC  210  may provide a proximity notification signal N_px, indicating that a conductive object is in the proximity, to the host  300 . 
     In an example embodiment, the TSC  210  may perform touch sensing for the touch sensor  110  and noise sensing (e.g., display noise sensing) at the same time or at different times, and may process touch data generated through the touch sensing based on noise data (e.g., display noise data) generated through the noise sensing. For example, the TSC  210  may generate compensated touch data by removing noise data from touch data. For example, the TSC  210  may discard touch data when noise data exceeds a predetermined value. Discarded touch data may be frame data corresponding to one frame of the touch sensor  110 . 
     In an example embodiment, the TSC  210  may perform noise sensing at the same time as the touch sensing for the touch sensor  110 , and may remove a noise sensing signal from a touch sensing signal to generate touch data from which noise is removed. 
     In an example embodiment, the TSC  210  may receive, as compensation information, voltage changes at a plurality of points on the display panel  120  (which cause components of display noise to the touch sensor  110 ) or offset values (which are calculated based on the voltage changes) from the DDI  220 , and may remove components of display noise from touch data or discard the touch data based on the compensation information. 
     As described above, because the TSC  210  removes a noise sensing signal from a touch sensing signal or processes touch data based on noise data, the reliability of touch data may be improved, and touch sensing sensitivity may be improved. 
     The method of sensing pieces of noise performed by the TSC  210 , the method of generating voltage changes performed by the DDI  220 , and the method of processing touch data based on voltage changes performed by the TSC  210  will each be described below in more detail with reference to  FIGS.  2  to  20   . 
     Still referring to  FIG.  1   , the DDI  220  may receive image data IDT from the host  300 , and may drive the display panel  120  to display an image according to the image data IDT on the display panel  120 . The DDI  220  may convert the image data IDT into image signals Simg, which are analog signals, and provide the image signals Simg to corresponding pixels of the display panel  120 . 
     The host  300  may perform an overall control operation for the touch screen device  1000 . The host  300  may generate data related to a display operation, and may provide the data to the DDI  220 . The host  300  may receive touch information like a touch coordinate Txy or a proximity notification signal N_px from the TSC  210 , and may perform control operations using the touch information. For example, when a proximity notification signal N_px is received while a display operation is being performed, the host  300  may stop a display operation by providing a control signal for stopping the display operation to the DDI  220 . 
     In an example embodiment, the host  300  may include an application processor (AP). The AP may be implemented as a system-on-chip (SoC). The SoC may include a system bus (not shown) to which a predetermined standard bus protocol is applied, and may include various intellectual properties (IPs) connected to the system bus. As a standard protocol for the system bus, various types of protocols like the advanced microcontroller bus architecture (AMBA) protocol of Advanced RISC Machine (ARM) may be applied. 
       FIG.  2    is a diagram schematically showing a TSC according to an example embodiment. For convenience of explanation, the touch sensor  110  will be shown together. 
     Referring to  FIG.  2   , the touch sensor  110  may include a plurality of driving electrodes TE, e.g., first to sixth driving electrodes Y 1  to Y 6 . The touch sensor  110  may include a plurality of sensing electrodes RE, e.g., first to fourth receiving electrodes X 1  to X 4 . The number of driving electrodes and the number of receiving electrodes included in the touch sensor  110  may be varied according to the resolution of the touch sensor  110 . 
     The driving electrodes TE may extend in a first direction, e.g., an X-axis direction, and the receiving electrodes RE may extend in a second direction orthogonal to the first direction, e.g., a Y-axis direction. The driving electrodes TE and the receiving electrodes RE may cross each other. A mutual capacitance C M  may be formed between a driving electrode TE and a receiving electrode RE crossing each other. 
     In an example embodiment, the driving electrodes TE and/or the receiving electrodes RE may include a plurality of unit electrodes connected to one another in the first direction or the second direction. The unit electrodes may each have a particular shape (e.g., a rhombus-like shape as shown in  FIG.  2   ) or may be in a particular pattern. 
     The TSC  210  may include a driving circuit  10 , a read-out circuit  20 , and a touch processor  30  (or control logic). 
     The driving circuit  10  may include a plurality of transmitters (TX)  11 . The plurality of TXs  11  may provide driving signals to the driving electrodes TE. Each of the plurality of TXs  11  may correspond to at least one driving electrode TE from among the driving electrodes TE, and the plurality of TXs  11  may provide a driving signal to the corresponding at least one driving electrode TE. A driving signal may be sequentially applied to the driving electrodes TE, or driving signals may be simultaneously applied to the driving electrodes TE. 
     In an example embodiment, driving signals modulated based on different codes may be simultaneously applied to two or more driving electrodes TE from among the driving electrodes TE, and this is referred to as multi-driving. For example, driving signals having opposite polarities may be simultaneously applied to a first driving electrode Y 1  and a second driving electrode Y 2 , and then driving signals having opposite polarities may be simultaneously applied to a third driving electrode Y 3  and a fourth driving electrode Y 4 . 
     The read-out circuit  20  may include a plurality of receivers (RX)  21  and an analog-digital converter (ADC)  23 . The plurality of RXs  21  may receive a plurality of sensing signals from the receiving electrodes RE. Each of the plurality of RXs  21  may be connected to one corresponding receiving electrode RE and receive a sensing signal or may be time-divisionally connected to at least two receiving electrodes RE and receive at least two sensing signals. 
     A sensing signal may include a touch signal indicating the mutual capacitance C M  between the driving electrode TE (to which a driving signal is applied) and the receiving electrode RE (by which the sensing signal is received). For example, when a touch occurs at one sensing node on the touch sensor  110 , the mutual capacitance C M  of the sensing node may decrease, and the level of the sensing signal may decrease or increase compared to that before the touch. 
     The sensing signal may include a noise signal, e.g., noise from the display or a display noise signal. For example, when touch sensing is performed during a display period in which an image is displayed on the display panel ( 120  in  FIG.  1   ), the sensing signal may include display noise due to the displaying of the image. According to a driving scheme of the driving circuit  10 , the sensing signal may include a touch signal and display noise, or may include display noise excluding a touch signal. 
     The RX  21  may process a sensing signal received from a corresponding receiving electrode RE. For example, the RX  21  may convert a sensing signal (e.g., current-voltage conversion) or amplify the sensing signal. 
     The ADC  23  may analog-to-digital convert output signals of the plurality of RXs  21  (i.e., processed sensing signals), and may generate touch data and/or noise data. A plurality of touch values corresponding to a plurality of sensing nodes of the touch sensor  110  may be generated, and the touch values may be included in touch data of one frame. 
     The touch processor  30  may control the overall operation of the TSC  210  and, e.g., may control operation timings of the driving circuit  10  and the read-out circuit  20 . The touch processor  30  may determine whether a touch has occurred and a location of the touch based on touch data and/or noise data output from the ADC  23 , or may determine that a conductive object is in the proximity of the touch sensor  210 . 
     The touch processor  30  may include a noise processing module  31 . The noise processing module  31  may compensate for touch data based on noise data, or may determine whether to discard touch data based on noise data. For example, the noise processing module  31  may generate compensated touch data by subtracting noise data from touch data. For example, when the noise data is equal to or greater than a predetermined value, the noise processing module  31  may discard touch data without using the touch data to determine whether a touch has occurred, whether a conductive object is in the proximity, and/or a location of a corresponding touch. 
       FIG.  3    is a diagram for describing components of display noise introduced into a touch sensor stacked on a display panel. 
     In  FIG.  3   , the display panel  120  may include a display layer Ldp and a common electrode COM. The display layer Ldp may be formed on a substrate of the display panel  120 . The common electrode COM may be formed on the display layer Ldp. 
     The display layer Ldp may include a plurality of source lines S 1  to Sd (d is a positive integer). The plurality of source lines S 1  to Sd may be arranged in a first direction, e.g., the X-axis direction, and extend in a second direction, e.g., the Y-axis direction. Although not shown, the display layer Ldp may include a plurality of gate lines, and the plurality of gate lines may be arranged in the second direction and extend in the first direction. A plurality of pixels may be formed at points where the source lines S 1  to Sd and the gate lines cross each other. 
     Parasitic capacitance Cs may be formed between the source lines S 1  to Sd and the common electrode COM. When an image signal is applied to the source lines S 1  to Sd, the voltage of the common electrode COM may be changed due to the parasitic capacitance Cs. A constant voltage, e.g., a ground voltage VSS, may be applied to the common electrode COM. However, due to an RC delay caused by a parasitic resistance Rcom of the common electrode COM, when an image signal is applied to the source lines S 1  to Sd, the voltage of the common electrode COM may be changed. 
     A touch signal generated by the driving signal Stx provided from the TX  11  may be provided to the RX  21  as a sensing signal Ssen through a touch signal path. Meanwhile, parasitic capacitance C TX  or C RX  may be formed between the common electrode COM and the touch sensor  110 . Display noise generated as the voltage of the common electrode COM is changed may be introduced into the sensing signal Ssen through a display noise path formed by the parasitic capacitance C RX . 
     In general, the parasitic capacitance C RX  increases as a gap between the touch sensor  110  and the common electrode COM is narrowed, e.g., as in an ultra-thin touch screen panel (e.g.,  100  in  FIG.  1   ). Due to the increase in the parasitic capacitance C RX , the introduction of display noise to the sensing signal Ssen may increase, which may make it difficult to distinguish a touch signal from display noise, and difficult to determine whether a change in the sensing signal Ssen is caused by a touch input or display noise. According to the present example embodiment, the TSC ( 210  of  FIG.  1   ) separately senses display noise introduced into the touch sensor  110  to generate display noise data, and may process touch data based on the display noise data. 
       FIG.  4    is a diagram showing a display noise sensing method according to an example embodiment. The display noise sensing method of  FIG.  4    may be performed by the TSC  210  of  FIGS.  1  and  2   , and descriptions thereof will be given below with reference to  FIGS.  1  and  2    together. 
     Referring to  FIGS.  1 ,  2 , and  4   , the TSC  210  may receive sensing signals Ssen from a plurality of receiving electrodes (e.g., first to j-th receiving electrodes Xi to Xj (j is a positive integer)) without providing driving signals to a plurality of driving electrodes (e.g., first to k-th driving electrodes (k is a positive integer)) of the touch sensor  110 . The plurality of TXs  11  of the driving circuit  10  may be turned off, and the plurality of RXs  21  of the read-out circuit  20  may operate normally and receive sensing signals Ssen. Because driving signals are not provided to the touch sensor  110 , touch signals based on the driving signals are not generated and the sensing signals Ssen may not include touch signals. However, noise may be introduced into the touch sensor  110 , and the sensing signals Ssen may include the noise without the touch signal. 
     The TSC  210  may perform noise sensing by receiving the sensing signals Ssen from the plurality of receiving electrodes without providing the driving signals to the plurality of driving electrodes of the touch sensor  110  during a display period, and noise included in the sensing signals Ssen may be display noise. As described above, the TSC  210  may perform display noise sensing. 
     The sensing signals Ssen may include display noise, and the read-out circuit  20  may generate display noise data according to the display noise. As the amount of display noise generated increases, a data value of the display noise data may increase. 
     The noise processing module  31  may process touch data generated according to touch sensing based on display noise data generated according to display noise sensing. 
     According to the display noise sensing method according to the present example embodiment, because a driving signal is not applied to a plurality of driving electrodes, power consumption for display noise sensing may be reduced. 
       FIGS.  5 A and  5 B  are timing diagrams showing an operating method of a TSC according to an example embodiment. In  FIGS.  5 A and  5 B , the horizontal axis represents time. 
     Referring to  FIGS.  5 A and  5 B , the TSC ( 210  of  FIG.  2   ) may perform display noise sensing and touch sensing during a display period in which an image is displayed on the display panel ( 120  of  FIG.  1   ). 
     For example, the DDI ( 220  of  FIG.  1   ) may display an image of one frame on the display panel  120  in response to a vertical synchronization signal Vsync and may provide image signals to a plurality of source lines in response to a horizontal synchronization signal Hsync. Therefore, an image may be displayed on the display panel  120 . 
     The TSC  210  may perform display noise sensing in a first period P 1  and touch sensing in a second period P 2  different from the first period P 1 . The first period P 1  and the second period P 2  may overlap a display period, in which an image is displayed on the display panel  120 , on the time axis. Thus, display noise sensing and touch sensing may be performed during the display period. 
     The TSC  210  may perform display noise sensing according to the display noise sensing method described above with reference to  FIG.  4   . The TSC  210  may receive a timing signal, e.g., a vertical synchronization signal Vsync and a horizontal synchronization signal Hsync, from the DDI  220  and may perform display noise sensing in response to the horizontal synchronization signal Hsync. For example, the DDI  220  may provide image signals to a plurality of source lines of the display panel  120  in response to a rising edge or a falling edge of the horizontal synchronization signal Hsync, and, during an initial period in which image signals are provided in response to the horizontal synchronization signal Hsync, a large amount of display noise may occur. Therefore, the TSC  210  may improve display noise sensing efficiency by performing display noise sensing at a time point where a large amount of display noise occurs, in response to the horizontal synchronization signal Hsync. 
     The TSC  210  may sense one frame of the touch sensor  110  in the second period P 2 , as shown in  FIG.  5 A , or may divide and sense one frame of the touch sensor  110  in the second period P 2 , as shown in  FIG.  5 B . 
     Referring to  FIG.  5 A , the TSC  210  may sense one frame of the touch sensor  110 , e.g., first to k-th lines, in the second period P 2 . For example, as shown in  FIG.  4   , the touch sensor  110  may include first to k-th driving electrodes Y 1  to Yk, and the TSC  210  may sense the first to k-th lines in the second period P 2  by driving the first to k-th driving electrodes Y 1  to Yk by at least one line at a time. In this regard, the TSC  210  may perform display noise sensing in the first period P 1  before or after sensing one frame of the touch sensor  110 . 
     Referring to  FIG.  5 B , the TSC  210  may sense one frame of the touch sensor  110  by a plurality of lines at a time in the second period P 2 . For example, the TSC  210  may sense first to eighth lines of the touch sensor  110  in the earliest second period P 2 , and sense ninth to sixteenth lines of the touch sensor  110  in a second period P 2  after performing display noise sensing. Also, seventeenth to twenty-fourth lines of the touch sensor  110  may be sensed in a second period P 2  after performing display noise sensing again. In this regard, the TSC  210  may perform display noise sensing before, after, and in the middle of performing touch sensing for one frame of the touch sensor  110 . 
     The noise processing module ( 31  of  FIG.  2   ) may process touch data generated according to touch sensing based on display noise data generated according to display noise sensing. When processing a plurality of touch values included in touch data, the noise processing module  31  may process the touch values based on display noise data generated through display noise sensing performed at a time point closest to a time point at which lines corresponding to the touch values are sensed. 
       FIG.  6    is a diagram showing a display noise sensing method according to an example embodiment. The display noise sensing method of  FIG.  6    may be performed by the TSC  210  of  FIGS.  1  and  2   , and descriptions thereof will be given below with reference to  FIGS.  1  and  2    together. 
     Referring to  FIGS.  1 ,  2  and  6   , the TSC  210  may provide a positive driving signal Stx+ or a negative driving signal Stx− to a plurality of driving electrodes of the touch sensor  110 , e.g., the first to k-th driving electrodes Y 1  to Yk, at the same time. For example, the TSC  210  may apply a positive driving signal Stx+ to at least one driving electrode, and may apply a negative driving signal Stx− to at least one other driving electrode adjacent to the at least one driving electrode. 
       FIG.  7    is a diagram showing a positive driving signal and a negative driving signal of  FIG.  6   . 
     Referring to  FIG.  7   , the positive driving signal Stx+ and the negative driving signal Stx− may include a plurality of pulse signals during a driving period Td, and the positive driving signal Stx+ and the negative driving signal Stx− may have the same frequency and opposite phases. However, the positive driving signal Stx+ and the negative driving signal Stx− may be sinusoidal waves having opposite phases and the same frequency. 
     Referring back to  FIG.  6   , the positive driving signal Stx+ and the negative driving signal Stx− may be alternately applied to per driving electrode, the positive driving signal Stx+ may be applied to a first driving electrode Y 1 , and the negative driving signal Stx− may be applied to a second electrode Y 2 . However, the positive driving signal Stx+ and the negative driving signal Stx− may be alternately applied to at least two driving electrodes. The number of driving electrodes to which the positive driving signal Stx+ is applied may be the same as the number of driving electrodes to which the negative driving signal Stx− is applied. 
     According to the noise sensing method of  FIG.  6   , as driving signals of opposite polarities are applied to adjacent driving electrodes, a positive touch signal due to the positive driving signal Stx+ and a negative touch signal due to the negative driving signal Stx− may offset each other. Therefore, sensing signals output through a plurality of receiving electrodes X 1  to Xj do not include a touch signal and may include display noise. Display noise is amplified by the positive driving signal Stx+ and the negative driving signal Stx−, and thus, display noise sensing efficiency may be improved. Also, when the frequencies of the positive driving signal Stx+ and the negative driving signal Stx− are changed, display noise may be amplified or attenuated. Therefore, according to the display noise sensing method, display noise sensing efficiency may be improved. 
       FIG.  8    is a flowchart of an operating method of the TSC  210  according to an example embodiment. The method of  FIG.  8    may be performed by the TSC  210  of  FIGS.  1  and  2   . Descriptions thereof will be given with reference to  FIG.  2    together. 
     Referring to  FIG.  8   , the TSC  210  may generate display noise data by performing display noise sensing in a first period of a display period (operation S 110 ). The TSC  210  may sense display noise according to the display noise sensing method described above with reference to  FIG.  4  or  6   . 
     As described above, the TSC  210  may not apply a driving signal to a plurality of driving electrodes TE. In another example, the TSC  210  may apply a positive driving signal and a negative driving signal to the driving electrodes TE, e.g., a positive driving signal may be applied to at least one driving electrode TE, and a negative driving signal may be applied to at least one other driving electrode TE adjacent to the at least one driving electrode TE. 
     The TSC  210  may receive sensing signals from a plurality of receiving electrodes RE, and the sensing signals may include display noise. The TSC  210  may generate display noise data based on display noise. 
     The TSC  210  may generate touch data by performing touch sensing in a second period of the display period (operation S 120 ). The TSC  210  may sequentially apply driving signals to the driving electrodes TE and receive sensing signals from the receiving electrodes RE every time driving signals are applied to the driving electrodes TE. The sensing signals may include signals, and, when display noise occurs, the touch signals may include the display noise. The TSC  210  may generate touch data based on a sensing signal. The touch data may include a display noise component. 
     The TSC  210  may process the touch data based on display noise data (operation S 130 ). As described above, the TSC  210  may generate compensated touch data by subtracting display noise from the touch data. When the display data exceeds a predetermined value, the TSC  210  may determine that display noise has occurred and discard the touch data. 
       FIG.  9    is a block diagram schematically showing a TSC according to an example embodiment. A TSC  210   a  of  FIG.  9    may be applied as the TSC  210  of  FIG.  1   . For convenience of explanation, the touch sensor  110  will be shown together. 
     Referring to  FIG.  9   , the TSC  210   a  may include the driving circuit  10 , a read-out circuit  20   a , and a switching circuit (SW)  40 . The TSC  210   a  may further include the touch processor  30  described with reference to  FIG.  2   . 
     Because the driving circuit  10  is the same as the driving circuit  10  described above with reference to  FIG.  2   , descriptions identical to those given above will be omitted. 
     The read-out circuit  20   a  may include a plurality of first receivers (RX1)  21   a , at least one second receiver (RX2)  22   a , and the ADC  23 . The plurality of RX1s  21   a  may sense a touch signal, and the at least one RX2  22   a  may sense display noise. Thus, the plurality of RX1s  21   a  may perform touch sensing, and the at least one RX2  22   a  may perform display noise sensing. The plurality of RX1s  21   a  may be referred to as touch sensing circuits, and the at least one RX2  22   a  may be referred to as a display noise reference sensing circuit. 
     The plurality of RX1s  21   a  may receive a plurality of first sensing signals Ssen 1  from a plurality of receiving electrodes RE, e.g., first to j-th receiving electrodes X 1  to Xj. The first sensing signal Ssen 1  may include a touch signal. When display noise occurs, the touch signal may include display noise. The plurality of RX1s  21   a  may each process and output a received first sensing signal Ssen 1 . For example, the plurality of RX1s  21   a  may each current-voltage convert the first sensing signal Ssen 1  to generate a sensing voltage, filter a frequency of the sensing voltage, and amplify a gain of a frequency-filtered sensing voltage. In another example, the RX1  21   a  may current-voltage convert the first sensing signal Ssen 1  to generate a sensing voltage and integrate the sensing voltage. 
     The RX2  22   a  may receive a second sensing signal Ssen 2  from at least one driving electrode TE (hereinafter referred to as a first reference electrode) selected from among driving electrodes TE to which a driving signal Stx is not applied, e.g., a (k−1)-th driving electrode Yk−1. The second sensing signal Ssen 2  may include display noise. The RX2  22   a  may process and output the second sensing signal Ssen 2 . 
     The ADC  23  may generate touch data and display noise data through analog-to-digital conversion of output signals of the plurality of RX1s  21   a  and output signals of the RX2s  22   a.    
     The switching circuit  40  may select a first reference electrode to which the second sensing signal Ssen 2  is output from among the driving electrodes TE, e.g., the first to k-th driving electrodes Y 1  to Yk. The switching circuit  40  may select the first reference electrode from among driving electrodes TE to which a driving signal Stx is not applied. Thus, the switching circuit  40  may electrically connect the first reference electrode selected from among driving electrodes TE, to which a driving signal Stx is not applied, to the RX2  22   a.    
     When performing touch sensing, a driving signal Stx may be sequentially applied to the driving electrodes TE at least one driving electrode TE at a time, and thus, the driving electrodes TE may be sequentially driven. The switching circuit  40  may change the first reference electrode, such that another driving electrode TE to which the driving signal Stx is not applied may be connected to the RX2  22   a  as the first reference electrode. 
     For example, when the driving signal Stx is applied to the first driving electrode Y 1 , the switching circuit  40  may select one of second to k-th driving electrodes Y 2  to Yk to which the driving signal Stx is not applied as the first reference electrode. The switching circuit  40  may select a (k−1)-th driving electrode Yk−1 spaced apart from the first driving electrode Y 1  as the first reference electrode. For example, when the driving signal Stx is applied to the second driving electrode Y 2 , the switching circuit  40  may select one of the first driving electrode Y 1  and third to k-th driving electrodes Y 3  to Yk to which the driving signal Stx is not applied as the first reference electrode and connect the first reference electrode to the RX2  22   a.    
     In an example embodiment, the plurality of RX1s  21   a  and the at least one RX2  22   a  may also receive a third sensing signal Ssen 3  from at least one driving electrode TE (hereinafter, referred to as a second reference electrode) from among the driving electrodes TE to which the driving signal Stx is not applied, e.g., a k-th driving electrode Yk. The third sensing signal Ssen 3  may include display noise. The second reference electrode, by which the third sensing signal Ssen 3  is received, is different from the first reference electrode by which the second sensing signal Ssen 2  is received. 
     The plurality of RX1s  21   a  may generate a touch sensing signal based on the first sensing signal Ssen 1  and the third sensing signal Ssen 3 , and the at least one RX2  22   a  may generate a display noise reference signal based on the second sensing signal Ssen 2  and the third sensing signal Ssen 3 . The ADC  23  may generate touch data and display noise data through analog-to-digital conversion of the touch sensing signal and the display noise reference signal. 
     The switching circuit  40  may select a second reference electrode to which the third sensing signal Ssen 3  is output from among the driving electrodes Y 1  to Yk. The switching circuit  40  may select the second reference electrode from among driving electrodes to which the driving signal Stx is not applied. 
     When performing touch sensing, as the driving electrodes TE are sequentially driven, the switching circuit  40  may change the second reference electrode, such that the third sensing signal Ssen 3  is output from the driving electrode TE to which the driving signal Stx is not applied. 
     For example, when the driving signal Stx is applied to the first driving electrode Y 1 , the (k−1)-th driving electrode Yk−1 may be selected as the first reference electrode and the second sensing signal Ssen 2  may be received from the (k−1)-th driving electrode Yk−1, and the k-th driving electrode Yk may be selected as the second reference electrode and the third sensing signal Ssen 3  may be received from the k-th driving electrode Yk. However, the k-th driving electrode Yk may be selected as the first reference electrode, and the (k−1)-th driving electrode Yk−1 may be selected as the second reference electrode. 
     Although  FIG.  9    shows that two adjacent driving electrodes TE (e.g., the (k−1)-th driving electrode Yk−1 and the k-th driving electrode Yk) are selected as the first reference electrode and the second reference electrode, respectively, another driving electrode TE may be disposed between the first reference electrode and the second reference electrode, and at least one of the first reference electrode and the second reference electrode may include two or more adjacent driving electrodes TE. 
       FIG.  10    is a diagram schematically showing operations of a read-out circuit and a read-out circuit according to an example embodiment. 
     Referring to  FIG.  10   , the read-out circuit  20   a  may include the plurality of RX1s  21   a , the RX2  22   a , and the ADC  23 . As described with reference to  FIG.  9   , the read-out circuit  20   a  may include the plurality of RX1s  21   a . Because the operation of the plurality of RX1s  21   a  is the same, for convenience of explanation, one RX1  21   a  connected to a first receiving electrode X 1  is shown in  FIG.  10   . 
     As described above with reference to  FIG.  3   , parasitic capacitances C TX1  and C TX2  may be formed between the common electrode COM and the driving electrodes, e.g., the (k−1)-th driving electrode Yk−1 and the k-th driving electrode Yk, of the display panel  120 , and a parasitic capacitance C RX  may be formed between the common electrode COM and a receiving electrode, e.g., the first receiving electrode X 1 . 
     A touch signal generated by the driving signal Stx provided from the TX  11  may be provided to the RX1  21   a  connected to the first receiving electrode X 1  as the first sensing signal Ssen 1 . When display noise occurs in the common electrode COM, display noise may be introduced into the first receiving electrode X 1  through a noise path formed by the parasitic capacitance C RX  and may be included in the first sensing signal Ssen 1 . Therefore, the first sensing signal Ssen 1  may include a touch signal and display noise. 
     The second sensing signal Ssen 2  output from the first reference electrode, e.g., the (k−1)-th driving electrode Yk−1, may be provided to the RX2  22   a . Display noise may be introduced into the (k−1)-th driving electrode Yk−1 through a noise path formed by the parasitic capacitance C TX 1, and display noise may be provided to the RX2  22   a  as the second sensing signal Ssen 2 . 
     The third sensing signal Ssen 3  output from the second reference electrode, e.g., the k-th driving electrode Yk, may be provided to the RX1  21   a  and the RX2  22   a . Display noise may be introduced into the k-th driving electrode Yk through a noise path formed by the parasitic capacitance C TX2 , and display noise may be provided to the RX1  21   a  and the RX2  22   a  as the third sensing signal Ssen 3 . 
     The RX1  21   a  may include a first current amplifier CA 1 , a first filter FT 1 , and a first gain amplifier GA 1 . The RX1  21   a  may further include a first switch SW 1 . 
     The first current amplifier CA 1  may include a first input terminal I 11  and a second input terminal I 12 . The first sensing signal Ssen 1  may be received through the first input terminal I 11  and the third sensing signal Ssen 3  may be received through the second input terminal I 12 . The first current amplifier CA 1  may amplify an amount of a current corresponding to a difference between the first sensing signal Ssen 1  and the third sensing signal Ssen 3  and convert the amplified amount of the current into a first sensing voltage. 
     The first filter FT 1  may filter the frequency of the first sensing voltage output from the first current amplifier CA 1 . For example, the first filter FT 1  may be implemented as a low-pass filter that passes a frequency band lower than or equal to a first frequency, and thus, the first filter FT 1  may pass a frequency component lower than or equal to the first frequency from among the frequency components of the first sensing voltage and block frequency components higher than the first frequency. For example, the first filter FT 1  may remove high frequency noise from the first sensing voltage. The first filter FT 1  may output a first sensing voltage from which high frequency noise is removed. 
     The first gain amplifier GA 1  may amplify a first sensing voltage output from the first filter FT 1 . For example, the first gain amplifier GA 1  may have a first gain and may amplify the magnitude of the first sensing voltage by the first gain. The first gain amplifier GA 1  may output an amplified first sensing voltage as a touch sensing signal. 
     The first switch SW 1  may be turned on or turned off in response to a first enable signal EN 1 . The first enable signal EN 1  may be received from the touch processor ( 30  of  FIG.  2   ). When the first switch SW 1  is turned on, a touch sensing signal may be provided to the ADC  23 . 
     The RX2  22   a  may include a second current amplifier CA 2 , a second filter FT 2 , and a second gain amplifier GA 2 . The RX2  22   a  may further include a second switch SW 2 . 
     The second current amplifier CA 2  may include a first input terminal I 21  and a second input terminal I 22 . The second sensing signal Ssen 2  may be received through the first input terminal I 21  and the third sensing signal Ssen 3  may be received through the second input terminal I 22 . The second current amplifier CA 2  may amplify an amount of a current corresponding to a difference between the second sensing signal Ssen 2  and the third sensing signal Ssen 3  and convert the amplified amount of the current into a second sensing voltage. 
     The second filter FT 2  may filter the frequency of the second sensing voltage output from the second current amplifier CA 2 . For example, the second filter FT 2  may be implemented as a low-pass filter that passes a frequency band lower than or equal to a second frequency, and thus, the second filter FT 2  may pass a frequency component lower than or equal to the second frequency from among the frequency components of the second sensing voltage and block frequency components higher than the second frequency. For example, the second filter FT 2  may remove high frequency noise from the second sensing voltage. The second filter FT 2  may output a second sensing voltage from which high frequency noise is removed. The second frequency of the second filter FT 2  may be the same as or different from the first frequency of the first filter FT 1 . 
     The second gain amplifier GA 2  may amplify a second sensing voltage output from the second filter FT 2 . For example, the second gain amplifier GA 2  may have a second gain and may amplify the magnitude of the second sensing voltage by the second gain. The second gain amplifier GA 2  may output an amplified second sensing voltage as a display noise reference signal. The second gain of the second gain amplifier GA 1  may be the same as or different from the first gain of the first gain amplifier GA 1 . 
     The second switch SW 2  may be turned on or turned off in response to a second enable signal EN 2 . A third enable signal EN 2  may be received from the touch processor ( 30  of  FIG.  2   ). When the third switch SW 3  is turned on, a display noise reference signal may be provided to the ADC  23 . 
     The ADC  23  may convert a plurality of touch sensing signals sequentially received from the plurality of RX1s  21   a  into a plurality of touch values. Therefore, touch data including a plurality of touch values corresponding to a plurality of sensing nodes on the touch sensor ( 110  of  FIG.  2   ) may be generated. The ADC  23  may also convert a display noise reference signal received from the RX2  22   a  into display noise data. 
     As described above, the read-out circuit  20   a  according to an example embodiment may include the RX2  21   a  for display noise sensing, separate from the RX1  20   a  for performing touch sensing. When the RX1  20   a  performs touch sensing, the RX2  21   a  may simultaneously perform display noise sensing. Therefore, the RX2  21   a  may detect a change in display noise in real time. 
       FIG.  11    is a diagram schematically showing operations of a read-out circuit and a read-out circuit according to an example embodiment. A read-out circuit  20   b  of  FIG.  11    may be a modified example of the read-out circuit  20   a  of  FIG.  10   . Therefore, the descriptions given above with reference to  FIG.  10    may also be applied to the operation of the read-out circuit  20   b  of  FIG.  11   . 
     Referring to  FIG.  11   , the read-out circuit  20   b  may include an RX1  21   b , an RX2  22   b , and the ADC  23 . 
     The RX1  21   b  may include the first current amplifier CA 1 , the first filter FT 1 , the first gain amplifier GA 1 , a differential amplifier CA, and the first switch SW 1 . The RX2  22   b  may include the second current amplifier CA 2 , the second filter FT 2 , and the second gain amplifier GA 2 . As compared with the read-out circuit  20   a  of  FIG.  10   , the RX1  21   b  may further include the differential amplifier CA. 
     The differential amplifier CA may amplify a difference between a touch sensing signal (output from the first gain amplifier CA 1 ) and a display noise reference signal (output from the second gain amplifier GA 2  of the RX2  22   b ), and output a compensated touch sensing signal. Therefore, display noise may be removed from the touch sensing signal. 
     The ADC  23  may convert a compensated touch sensing signal output from the differential amplifier CA into a touch value. The ADC  23  may receive a plurality of touch sensing signals sequentially from the plurality of RX1s  21   a , and convert the touch sensing signals into a plurality of touch values. Therefore, touch data from which display noise is removed may be generated. 
       FIG.  12    is a flowchart of an operating method of the TSC  210  according to an example embodiment. The operating method of the TSC  210  of  FIG.  12    may be performed by the TSC  210  of  FIGS.  1  and  2   , the read-out circuit  20   a  of  FIG.  11   , and the read-out circuit  20   b  of  FIG.  12   . 
     Referring to  FIG.  12   , the TSC  210  may apply a driving signal to at least one driving electrode from among a plurality of driving electrodes (operation S 210 ). 
     A plurality of RX1s (e.g.,  21   a  of  FIG.  11   ) provided in the TSC  210  may perform touch sensing (operation S 220 ). The plurality of RX1s  21   a  may perform touch sensing by receiving and processing a first sensing signal from corresponding receiving electrodes from among a plurality of receiving electrodes. 
     At least one RX2 (e.g.,  22   a  of  FIG.  11   ) provided in the TSC  210  may perform display noise sensing (operation S 230 ). The at least one RX2  22   a  may perform display noise sensing by receiving and processing a second sensing signal from at least one other driving electrode to which a driving signal is not applied from among the driving electrodes. The touch sensing of operation S 220  may be simultaneously performed with the display noise sensing of operation S 230 , and the operating method of the TSC  210  according to an example embodiment may be performed during a display period in which an image is displayed on the display panel ( 120  of  FIG.  1   ). 
     In an example embodiment, the TSC  210  may generate touch data based on a touch sensing signal according to touch sensing, and may generate display noise data based on a display noise reference signal according to display noise sensing. The TSC  210  may process the touch data based on display noise data. 
     In an example embodiment, the TSC  210  may generate a compensated touch sensing signal by removing a display noise reference signal according to display noise sensing from a touch sensing signal according to touch sensing. The TSC  210  may generate touch data from which display noise is removed based on the compensated touch sensing signal. 
       FIG.  13    is a block diagram schematically showing a touch screen driving circuit  200   b  according to an example embodiment, and  FIG.  14    is a flowchart showing operations of a TSC  210   b  and a DDI  220   b  provided in the touch screen driving circuit  200   b  of  FIG.  13   . The touch screen driving circuit  200   b  may be applied to the touch screen driving circuit  200  of  FIG.  1   . 
     Referring to  FIG.  13   , the touch screen driving circuit  200   b  may include the TSC  210   b  and the DDI  220   b . As described with reference to  FIG.  1   , the TSC  210   b  may provide a driving signal to the touch sensor ( 110  of  FIG.  1   ), receive a sensing signal according to the driving signal from a touch sensor  110   b  to perform touch sensing, and detect the occurrence of a touch input (or proximity) and/or calculate a touch coordinate. The DDI  220   b  may convert image data received from the host ( 300  of  FIG.  1   ) into an image signal and drive the display panel ( 120  of  FIG.  1   ) based on the image signal, thereby displaying an image corresponding to the image data on the display panel  120 . 
     The DDI  220   b  may include an image data receiver  221 , an image data analyzer  222 , an image status information generator  223 , a reference map generator  224 , and a touch sensing offset generator  225 , and the TSC  210  may include a noise remover  211 . 
     Referring to  FIGS.  13  and  14    together, the image data receiver  221  may receive image data from the host ( 300  of  FIG.  1   ) (operation S 321 ). The image data receiver  221  may receive image data line by line. 
     The image data analyzer  222  may analyze received image data (operation S 312 ). For example, the image data analyzer  222  may calculate a data difference between lines of image data, that is, a data difference between a previous line and a current line. 
     The image status information generator  223  may generate image status information indicating a status of image data (operation S 313 ). For example, when there is a change in data equal to or greater than a threshold level between lines of image data, the image status information generator  223  may generate a condition flag CF indicating that a change in image data has occurred, as image status information. The DDI  220   b  may provide image status information, e.g., the condition flag CF, to the TSC  210   b.    
     The reference map generator  224  may generate a voltage map indicating an amount of voltage change that causes display noise or an impedance map indicating an impedance change, based on image data (operation S 315 ). The reference map generator  224  may include a coupling voltage map generator CVMG and/or an impedance map generator IPMG. The coupling voltage map generator CVMG may generate a coupling voltage map including coupling voltages at a plurality of points of the display panel  120 . The impedance map generator IPMG may generate an impedance map representing impedances at a plurality of points of the display panel  120 . The impedance map generator IPMG may generate an impedance map based on amounts of power voltage drops at a plurality of points of the display panel  120  according to image data, e.g., amounts of IR-drops of a power voltage (or IR-drop map). A method of generating a coupling voltage map will be described later with reference to  FIG.  14   , and a method of generating an impedance map will be described later with reference to  FIGS.  15  to  17   . 
     The touch sensing offset generator  225  may calculate a touch sensing offset OFS based on at least one of a voltage map generated by the reference map generator  224 , e.g., a coupling voltage map and an impedance map. The touch sensing offset OFS may include an offset value indicating a change amount of a touch value according to occurrence of display noise. The touch sensing offset generator  225  may calculate offset values according to a resolution of the touch sensor  110 , that is, offset values corresponding to respective sensing nodes of the touch sensor  110 . The DDI  220   b  may provide a touch sensing offset OFS to the TSC  210   b  (operation S 317 ). 
     The TSC  210   b  may perform touch sensing (operation S 321 ) and generate touch data according to the touch sensing (operation S 322 ). When image status information received from the DDI  220   b  indicates an image change, the TSC  210   b  may determine that display noise may occur. 
     The TSC  210   b  may compensate for touch data by applying a touch sensing offset OFS to the touch data (operation S 323 ). For example, the noise remover  211  may compensate for touch data by subtracting offset values from the touch data. As a result, display noise may be removed from touch data. 
     The TSC  210   b  may determine whether a touch has occurred (or whether a conductive object is in the proximity) or calculate a touch coordinate based on the compensated touch data (operation S 324 ). 
     As described above, in the touch screen driving circuit  200   b  according to an example embodiment, the DDI  220   b  generates a voltage map by calculating amounts of voltage changes at a plurality of points on the display panel  120  that cause display noise based on image data, calculates a touch sensing offset OFS based on the voltage map, and provides the touch sensing offset OFS to the TSC  210   b . The TSC  210   b  may compensate for touch data based on the touch sensing offset OFS, thereby removing display noise from the touch data. 
     Components included in the DDI  220   b  and TSC  210   b , e.g., the image data receiver  221 , the image data analyzer  222 , the image status information generator  223 , the reference map generator  224 , the touch sensing offset generator  225 , and the noise remover  211 , may be implemented as hardware components, software components, or combinations of hardware and software. For example, components included in the DDI  220  and the TSC  210  may be implemented as hardware logic circuits. In another implementation, components included in the DDI  220  and the TSC  210  may be implemented as programs each including a plurality of instructions, may be stored in a memory provided in the DDI  220   b  and/or the TSC  210   b , and may be executed by a processor provided in the DDI  220   b  and/or the TSC  210   b.    
     The TSC  210   b  and the DDI  220   b  may be integrated on one semiconductor chip or may be separately implemented on a plurality of semiconductor chips. A semiconductor chip in which the TSC  210   b  and the DDI  220   b  are integrated may be referred to as a TDDI. In a TDDI, the TSC  210   b  and the DDI  220   b  may each include a communication port for transmitting and receiving data or signals to and from each other, and the DDI  220   b  may transmit image status information, e.g., a condition flag CF and a touch sensing offset OFS, to the TSC  210   b  through a communication port to which a set interface scheme is applied. Also, the DDI  220   b  may transmit display status information DS to the TSC  210   b  through the communication port. For example, in a standby period in which no image is displayed on the display panel  120 , the DDI  220   b  may provide a standby signal to the TSC  210   b  as the display state information DS. 
       FIG.  15    is a flowchart of a method of generating a coupling voltage map according to an example embodiment. The method of  FIG.  15    may be performed by the coupling voltage map generator CVMG of  FIG.  13   . 
     Referring to  FIG.  15   , the coupling voltage map generator CVMG may convert pixel data into a voltage (operation S 410 ). The coupling voltage map generator CVMG may include mapping information representing voltage values corresponding to pixel data or may receive mapping information from an external source, e.g., the host  300 . The coupling voltage map generator CVMG may convert pixel data into a voltage (e.g., a digital signal representing a voltage) based on the mapping information. Pieces of pixel data included in image data may be converted into a plurality of voltages. 
     The coupling voltage map generator CVMG may calculate a coupling voltage for each line based on converted voltages (operation S 420 ). The coupling voltage map generator CVMG may calculate a coupling voltage by comparing voltages corresponding to pixel data of a previous line with voltages corresponding to pixel data of a current line. 
     The coupling voltage map generator CVMG may determine a ratio map indicating application ratios of a coupling voltage according to locations (operation S 430 ). 
     The coupling voltage map generator CVMG may calculate a coupling voltage based on voltages calculated in operation S 420  and the ratio map determined in operation S 430  (operation S 440 ). 
     A coupling voltage ΔVn may be generated according to Equation 1: 
     
       
         
           
             
               
                 
                   
                     Δ 
                     ⁢ 
                     
                       V 
                       n 
                     
                   
                   = 
                   
                     
                       
                         ( 
                         
                           α 
                           × 
                           
                             [ 
                             
                               
                                 ∑ 
                                 
                                   ( 
                                   
                                     
                                       V 
                                       n 
                                     
                                     - 
                                     
                                       V 
                                       
                                         n 
                                         - 
                                         1 
                                       
                                     
                                   
                                   ) 
                                 
                               
                               
                                 ( 
                                 
                                   # 
                                   ⁢ 
                                   Hpx 
                                 
                                 ) 
                               
                             
                             ] 
                           
                         
                         ) 
                       
                       × 
                       γ 
                     
                     + 
                     
                       ( 
                       
                         β 
                         × 
                         Δ 
                         ⁢ 
                         
                           V 
                           
                             n 
                             - 
                             1 
                           
                         
                       
                       ) 
                     
                   
                 
               
               
                 
                   [ 
                   
                     Equation 
                     ⁢ 
                          
                     1 
                   
                   ] 
                 
               
             
           
         
       
     
     In Equation 1, the values of α, β, and γ may be determined based on optically and visually measured values during calculation of the coupling voltage. 
     In Equation 1, α denotes an application ratio of the coupling voltage at the current line, e.g., the n-th line. The value of α may be determined by a degree to which a voltage range of a coupling voltage ΔVn causing coupling is changed. The value of a may be increased or decreased based on whether a voltage is increasing or decreasing. 
     In Equation 1, the value of γ may be varied depending on the location of the current line on the display panel  120 . 
     In Equation 1, β denotes an effect of the previous line, e.g., the application ratio of the coupling voltage according to a location of the current line on the display panel  120 . The value of β may be set according to a degree of stabilization of a ripple due to the coupling voltage of the previous line. 
     In Equation 1, V n  denotes a voltage of pixels of a current line, e.g., an n-th line. 
     In Equation 1, V n-1  denotes a voltage of pixels of a previous line, e.g., a coupling voltage at the previous line or (n−1)-th line. 
     In Equation 1, Σ(V n −V n-1 ) denotes the sum of voltage differences between the current line and the previous line corresponding to pixels included in one line. 
     In Equation 1, #Hpx denotes the number of pixels included in one line. 
     Therefore, in Equation 1, 
               ∑     (       V   n     -     V     n   -   1         )         (     #   ⁢   Hpx     )           
represents a coupling voltage at the current line as an average of voltage differences at the current line.
 
     The coupling voltage map generator CVMG may generate a coupling voltage map including coupling voltages calculated for a plurality of locations on a display panel (operation S 450 ). 
       FIG.  16    is a diagram showing a structure of a power line of the display panel  120 . 
     Referring to  FIG.  16   , a power line through which a power voltage Vdd is transmitted from the display panel  120  may include an external power line PLe and an internal power line PLi. The external power line PLe may include an external circuit that provides the power voltage Vdd, e.g., a unidirectional wire that transmits the power voltage Vdd from a DDI (DDI  220   b  of  FIG.  13   ) or a voltage generator. The internal power line PLi may include wires in the form of a meshed grid formed inside the display panel  120 . 
     The external power line PLe may be modeled as parasitic resistances Ri and Ro, and the internal power line PLi may be modeled as a plurality of parasitic resistances Rv and Rh. Pixels PX may be arranged at lattice points of the internal power line PLi, and a pixel PX may include a light emitting device like an organic light emitting diode (OLED), a driving transistor Td, and a storage capacitor Cst. An image signal, e.g., a data voltage Vd(n,m), may be applied to the pixel PX, and the data voltage Vd(n,m) may be stored in the storage capacitor Cst. A pixel current Ip(n,m) according to the data voltage Vd(n,m) may be provided to the OLED through the driving transistor Td. Here, n and m are positive integers, n denotes a line, e.g., a row, on the display panel  120  where the pixel PX is located, and m denotes a column where the pixel PX is located. 
     A voltage drop of the power voltage Vdd caused by a parasitic resistance present in a power line and a pixel current Ip, which varies depending on an input image, e.g., a data voltage Vd, may be referred to as an IR-drop or a loading effect. 
     The IR-drop phenomenon may be divided into a global IR-drop phenomenon and a local IR-drop phenomenon. An IR-drop occurring in the external power line PLe due to the parasitic resistances Ri and Ro of the external power line PLe and a current It flowing through the external power line PLe may affect all of the pixels PX of the display panel  120 , thereby causing a global IR-drop phenomenon. In the internal power line PLi, since an amount of a current flowing therein varies according to locations, the size of an IR-drop may be varied according to the locations. Therefore, the size of an IR-drop affecting the pixel PX varies, and this may be referred to as a local IR-drop phenomenon. 
     A global IR-drop phenomenon and a local IR-drop phenomenon may occur differently depending on an image signal input to the display panel  120 , e.g., the data voltage Vd, and brightness setting. An IR-drop phenomenon affects display noise, thereby affecting touch data. 
     A global IR-drop Vgid may be expressed by Equation 2:
 
 Vgid=It ×( Ri+Ro )  [Equation 2]
 
     A local IR-drop will be described below with reference to  FIGS.  17  and  18   . 
       FIG.  17    is a modeling diagram showing an internal structure of the display panel  120 , and  FIG.  18    is a graph showing a power voltage decreased in one column of the display panel  120 . 
     Referring to  FIG.  17   , the display panel  120  may include a plurality of data lines DL and a plurality of scan lines SL, wherein the data lines DL may extend in a second direction, e.g., the Y-axis direction, and the scan lines SL may extend in a first direction, e.g., the X-axis direction. A data line DL and a scan line SL may be referred to as a source line and a gate line, respectively. 
     A plurality of pixels PX may be arranged in rows and columns. For example, the pixels PX may be arranged in N rows and M columns (N and M are positive integers). The data line DL and the scan line SL may be connected to each of the pixels PX. N scan signals Vg- 1  to Vg-N may be sequentially applied to N scan lines SL. M data voltages Vd- 1  to Vd-M may be simultaneously applied to M data lines DL. The M data voltages Vd- 1  to Vd-M may be applied to M pixels PX connected to the scan line SL to which a scan signal is applied. A pixel current may flow according to applied data voltages. For example, a data voltage Vd-M may be applied to a pixel arranged at an N-th row and an M-th column, and a pixel current Ip(N,M) according to the data voltage Vd-M may flow through a driving transistor. Pixel currents flowing through the respective pixels PX may flow through the internal power line PLi, and thus local IR-drops Vlid at a plurality of points may be different from one another. 
     A local IR-drop Vlid(n,m) that affects a power voltage applied to the pixel PX arranged at an n-th row and an m-th column can be expressed by Equation 3:
 
 Vlid ( n,m )=Σ s=1   n ( Rp×Σ   r=s   N   Ip ( r,m ))  [Equation 3]
 
     In Equation 3, Rp denotes a parasitic resistance at each point of the internal power line PLi, Ip denotes a pixel current, and s and r may be positive integers. 
       FIG.  18    is a diagram showing the power voltage Vdd lowered by local IR-drops at respective points of one column, e.g., an M-th column. The horizontal axis corresponds to the second direction, e.g., the Y-axis direction, and may represent a distance to a point at which the power voltage Vdd is applied. As the distance from the point at which the power voltage Vdd is applied increases, the size of a local IR-drop may increase. Therefore, as the distance from the point where the power voltage Vdd is applied increases, the power voltage may decrease. 
     A power voltage Vdd′(n,m) supplied to each pixel PX may be expressed by Equation 4:
 
 Vdd ′( n,m )= Vdd −( Vgid+Vlid ( n,m ))  [Equation 4]
 
     An impedance map generator (e.g., IPMG of  FIG.  13   ) may calculate the pixel current Ip flowing through each pixel PX based on a data voltage applied to each pixel PX, and may calculate amounts of IR-drops representing amounts of changes of the power voltage VDD at a plurality of points on the display panel  120  by using Equations 2 to 4 based on pixel currents Ip and parasitic capacitors of the pixels PX, thereby generating an IR-drop map. The impedance map generator IPMG may generate an impedance map representing impedances at a plurality of points of the display panel  120  based on the IR-drop map. 
       FIG.  19    is a block diagram schematically showing a touch screen driving circuit  200   c  according to an example embodiment. 
     Referring to  FIG.  19   , the touch screen driving circuit  200   c  may include a TSC  210   c  and a DDI  220   c . The TSC  210   c  and the DDI  220   c  may be integrated in one semiconductor chip or in different semiconductor chips. 
     The DDI  220   c  may include the image data receiver  221 , the image data analyzer  222 , the image status information generator  223 , and the reference map generator  224 . 
     The TSC  210   c  may include a touch sensing offset generator  212  and the noise remover  211 . As compared with  FIG.  13   , the touch sensing offset generator  212  may be provided in the TSC  210   c  rather than the DDI  220   c.    
     The DDI  220   c  may provide a reference map RM including at least one of a coupling voltage map and an impedance map to the TSC  210   c . The touch sensing offset generator  212  of the TSC  210   c  may calculate a touch sensing offset including offset values corresponding to a plurality of sensing nodes of the touch sensor ( 110  of  FIG.  1   ) based on the reference map RM. 
     The noise remover  211  may generate compensated touch data by applying a touch sensing offset to touch data generated through touch sensing. 
       FIG.  20    is a flowchart of an operating method of the TSC  210  according to an example embodiment. 
     Referring to  FIG.  20   , the TSC  210  may determine whether it is in a display state (operation S 210 ). For example, the TSC  210  may receive status information indicating the display status from the DDI ( 220  of  FIG.  1   ) and determine whether it is in the display state (in which an image is being displayed on the display panel ( 120  of  FIG.  1   )) based on the status information. 
     When it is determined that it is in the display state, the TSC  210  may perform first touch sensing to obtain touch data and display noise data (operation S 220 ). The first touch sensing is a touch sensing operation that considers display noise, and may include performing of the display noise sensing described with reference to  FIGS.  4  to  8  and  9  to  12   , or application of offset values based on an amount of a voltage change causing display noise as described with reference to  FIGS.  13  to  19   . For example, the TSC  210  may obtain display noise data through display noise sensing at the same time as or at a different time from touch sensing, or may obtain display noise data based on an amount of a voltage change or a touch sensing offset received from the DDI  220 . 
     The TSC  210  may process the touch data based on display noise data (operation S 230 ). 
     Meanwhile, when it is determined that it is not in the display state, the TSC  210  may obtain touch data by performing second touch sensing that does not consider display noise (operation S 240 ). When it is not in the display state, it may be considered that no display noise occurs. Therefore, the TSC  210  may not perform the display noise sensing described with reference to  FIGS.  4  to  8  and  9  to  12   , or may not consider application of offset values based on an amount of a voltage change causing display noise as described with reference to  FIGS.  13  to  19   . 
     The TSC  210  may determine whether a touch has occurred or calculate a touch coordinate based on touch data or processed touch data (operation S 250 ). In an example embodiment, the TSC  210  may determine whether a conductive object is in the proximity of the touch sensor  110  based on touch-processed touch data. 
       FIGS.  21  and  22    are diagrams showing implementation examples of a touch screen driving circuit according to an example embodiment. 
     Referring to  FIG.  21   , the touch screen driving circuit  200  may include the TSC  210  and the DDI  220 . In an example embodiment, the TSC  210  and the DDI  220  may be implemented as separate semiconductor chips. In an example embodiment, at least one of the TSC  210  and the DDI  220  may be implemented as a plurality of semiconductor chips. 
     The TSC  210  and the DDI  220  may operate under the control of the host  300 , and the DDI  220  may receive image data IDT from the host  300  and drive the display panel ( 120  of  FIG.  1   ) to display an image according to the image data IDT on the display panel  120 . 
     The TSC  210  may scan the touch sensor ( 110  of  FIG.  1   ) and calculate a touch coordinate Txy based on sensing signals received from the touch sensor  110 , or detect a touch input (or a conductive object in the proximity). The TSC  210  may provide the touch coordinate Txy or a proximity notification signal N_px to the host  300 . 
     Referring to  FIG.  21   , the TSC  210  may include an analog-front end (AFE), a touch processor, a clock generator, and a voltage generator. 
     Also, the TSC  210  may include interface circuits for communication with the host  300  and the DDI  220 . As a non-limiting example, an interface circuit for communication with the host  300  may be implemented as one of various interfaces including a universal serial bus (USB) interface, a universal flash storage (UFS) interface, a multimedia controller (MMC) interface, an embedded MMC (eMMC) interface, a peripheral component interconnect express (PCIe) interface, an advanced technology attachment (ATA) interface, a serial advanced technology attachment (SATA) interface, a parallel advanced technology attachment (PATA) interface, a small computer system interface (SCSI), a serial attached SCSI (SAS), an enhanced small disk interface (ESDI), an integrated drive electronics (IDE) interface, and a high-speed serial interface, and an interface circuit for communication with the DDI  220  may be implemented as one from among a universal asynchronous receiver transmitter (UART) interface, an inter integrated circuit (I2C) interface, a serial peripheral interface (SPI), a mobile industry processor interface (MIPI), and an embedded display port (eDP) interface. 
     The AFE may include the driving circuit ( 10  of  FIG.  2   ) and the read-out circuit ( 20  of  FIG.  2   ). The AFE may further include the switching circuit ( 40  of  FIG.  9   ). The driving circuit ( 10  of  FIG.  2   ) and the read-out circuit ( 20  of  FIG.  2   ) may perform the above-described display noise sensing and touch sensing. 
     The clock generator may generate a clock signal used inside the TSC  210 , e.g., a clock signal provided to the driving circuit and the read-out circuit. 
     The voltage generator may generate voltages used in the AFE. 
     The touch processor may control the overall operation of the TSC  210 , and the touch processor may include the noise processing module  31  of  FIG.  2    and/or the noise remover  211  of  FIG.  13   . The touch processor may further include the touch sensing offset generator  212  of  FIG.  19   . 
     Operations of the driving circuit, the read-out circuit, and the touch processor have been described above with reference to  FIG.  2   , and thus descriptions identical to those will be omitted. 
     The DDI  220  may include a clock generator, a display controller, a voltage generator, a gamma block, an SRAM, a gate driver, and a source driver. Also, the DDI  220  may include interface circuits for communication with the host  300  and a touch driving circuit TDI. 
     The clock generator may generate clock signals used inside the DDI  220 , e.g., clock signals provided to the source driver and the gate driver. 
     The voltage generator may generate voltages used in the gate driver and the source driver. 
     The gamma block may generate a plurality of grayscale voltages corresponding to a plurality of grayscale levels that a pixel value may have and provide the same to the source driver. 
     The SRAM may store image data IDT received from the host  300 . For example, the SRAM may store image data IDT for a plurality of lines or image data IDT for one frame and provide the image data IDT to the source driver line by line. 
     The gate driver may sequentially provide scan signals to a plurality of scan lines provided in the display panel ( 120  of  FIG.  1   ). 
     The source driver may simultaneously provide image signals, e.g., data voltages, to a plurality of data lines provided in the display panel  120 . 
     The display controller may control the overall operation of the DDI  220 . In an example embodiment, the display controller may include the image data receiver  221 , the image data analyzer  222 , the image status information generator  223 , the reference map generator  224  of  FIG.  13   , and the touch sensing offset generator  225 . 
     In an example embodiment, the DDI  220  and the TSC  210  may communicate with each other, and the DDI  220  and the TSC  210  may include interface circuits for communication. As a non-limiting example, an interface circuit for communication between the DDI  220  and the TSC  210  may be implemented as one of various interfaces including a universal serial bus (USB) interface, a universal flash storage (UFS) interface, a multimedia controller (MMC) interface, an embedded MMC (eMMC) interface, a peripheral component interconnect express (PCIe) interface, an advanced technology attachment (ATA) interface, a serial advanced technology attachment (SATA) interface, a parallel advanced technology attachment (PATA) interface, a small computer system interface (SCSI), a serial attached SCSI (SAS), an enhanced small disk interface (ESDI), an integrated drive electronics (IDE) interface, and a high-speed serial interface, and an interface circuit for communication with the DDI  220  may be implemented as one from among a universal asynchronous receiver transmitter (UART) interface, an inter integrated circuit (I2C) interface, a serial peripheral interface (SPI), a mobile industry processor interface (MIPI), and an embedded display port (eDP) interface. 
     Referring to  FIG.  22   , the touch screen driving circuit  200  may include the TSC  210  and the DDI  220 . The touch screen driving circuit  200  may be integrated into one semiconductor chip, and touch screen driving circuit  200  may be referred to as a touch DDI (TDDI). 
     The TSC  210  may include an AFE and the touch processor for driving the touch sensor ( 110  of  FIG.  1   ). The DDI  220  may include the gate driver, the source driver, the SRAM, the gamma block, and the display controller for driving the display panel ( 120  of  FIG.  1   ). The TSC  210  or DDI  220  may include a clock signal generator that generates at least one clock signal used in the touch screen driving circuit  200  and a voltage generator that generates a plurality of voltages. Although  FIG.  21    shows that the clock generator is provided in the TSC  210  and the voltage generator is provided in the DDI  220 , this may be implemented differently. The touch screen driving circuit  200  may further include an interface circuit for communication with the host  300 . 
     The TSC  210  and the DDI  220  may communicate with each other within the touch screen driving circuit  200 , and the TSC  210  and the DDI  220  may include ports for communication with each other, e.g., a first port P 1  and a second port P 2 , respectively. Clock signals and voltages may be transmitted/received through data lines connected through the first port P 1  and the second port P 2 , and various types of data, e.g., the touch sensing offset OFS and the image status information (e.g., the condition flag CF, the display status information DS, or the reference map RM) described above with reference to  FIGS.  13  and  19   , may be transmitted/received. 
     By way of summation and review, a parasitic capacitance between a display panel and a touch sensor may increase as a distance between the display panel and a touch sensor becomes very small, e.g., as touch screens become ultra thin, and display noise occurring while performing a display may be introduced into the touch sensor by a parasitic capacitor. Such display noise may degrade touch sensing sensitivity. Also, when the touch sensor performs a proximity sensing function, a signal sensed by the touch sensor may be very weak, and thus, it may be difficult to distinguish a change in a sensing signal due to the proximity of a conductive object to the touch sensor from a change in a sensing signal resulting from display noise introduced into the touch sensor. 
     As described above, example embodiments may provide a touch sensor controller for improving touch sensing sensitivity, an operating method of the touch sensor controller, and a touch screen driving circuit including the touch sensor controller. 
     Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.