KR102651842B1 - Touch display device and method for driving the same - Google Patents

Abstract

The present invention relates to a touch display device capable of reducing power consumption and a method of driving the same, comprising a timing controller and a plurality of touch/data ICs, and transmitting an EPI interface between the timing controller and the plurality of touch/data ICs. In the touch display device connected through a line, the timing controller includes a transmitter to transmit display information to each of the plurality of touch/data ICs through the EPI interface transmission line, and each of the plurality of touch/data ICs has a receiving unit for receiving the display information through the EPI interface transmission line, and the transmitting unit of the timing controller or the receiving unit of each touch/data IC is driven with a first driving current during the data writing period, and the touch driving period. During the period, it is driven with a second driving current that is lower than the first driving current.

Description

Touch display device and driving method thereof {TOUCH DISPLAY DEVICE AND METHOD FOR DRIVING THE SAME}

The present invention relates to a touch display device that can reduce power consumption and a method of driving the same.

With the development of multimedia, the importance of flat panel display devices is increasing. In response to this, flat panel displays such as liquid crystal displays, plasma displays, and organic light emitting displays are being commercialized.

Among these, the OLED display device is a self-luminous device that emits light in an organic light-emitting layer by recombination of electrons and holes. It has high brightness, low driving voltage, and can be made into a thin film, so it is expected to be a next-generation display device.

Each of the plurality of pixels constituting the OLED display device includes an OLED element composed of an organic light-emitting layer between an anode and a cathode, and a pixel circuit that independently drives the OLED element. The pixel circuit includes a switching thin film transistor (TFT) that supplies data voltage to the storage capacitor, and a driving TFT that controls the driving current according to the driving voltage charged in the storage capacitor and supplies it to the OLED element. The device generates light proportional to the driving current.

In addition, a liquid crystal display device is formed by placing and bonding two substrates on which electrodes are formed so that the surfaces on which the two electrodes are formed face each other, and injecting a liquid crystal material between the two substrates. At this time, a voltage is applied to the two electrodes. By applying the electric field generated to move the liquid crystal molecules, the image is expressed by the light transmittance that changes accordingly.

Electrical characteristics such as resistance or capacitance change at the touch point where a hand or a stylus pen touches the flat display device as described above, detecting the touch point, and outputting information corresponding to the touch point. Touch display devices that stack touch panels that perform functions or operations are widely used.

Touch technology applied to the above flat panel display device is divided into add-on type and in-cell type depending on the location of the touch sensor. The add-on type is an external type in which a touch screen panel is attached to the display panel, and the in-cell type is an internal type in which the display panel and the touch screen are integrated by embedding touch electrodes in the display panel.

The in-cell type has been further advanced to slim the display device and is being developed into an Advanced In-cell Touch (AIT) display device that divides the common electrode of the liquid crystal display device and uses it as a touch electrode.

The AIT display device divides each frame period into a data writing period (data writing period) in which image data is written to the pixels, and a touch drive period in which a touch drive signal is applied to the touch electrodes and sensing whether or not a touch has been performed is used to create a touch display panel. Run .

In this way, in order to write image data to pixels in a time division manner and sense whether or not a touch is touched by touch electrodes, the timing controller and the panel driver are connected through an EPI (Embedded Point-to-point Interface) interface transmission line.

Also, during the data writing period, display information is transmitted from the timing controller to each data driver IC of the panel driver through the EPI interface transmission line.

Additionally, during the touch driving period, touch voltage information, etc. is transmitted from each data driving IC of the panel driver through the MCUfh SPI interface.

In this way, in order to transmit display information and touch voltage information through the EPI interface transmission line in a time division manner, each data driving IC of the timing controller and the panel driver is provided with a transmission/reception buffer (Tx/Rx buffer).

The transmission and reception buffers (Tx, Rx) are driven by a constant current both during the data writing period and the touch driving period.

Figure 1 is a waveform diagram of display information (Source output), EPI signal (EPI Signal), and driving current (Tx/Rx Current) of a transmission/reception buffer during a conventional data writing period.

As described above, in order to transmit display information through the EPI interface transmission line in a time division manner, the data writing period (display) and the touch driving period (touch) are determined by a touch synchronization signal (Tsync, not shown in the figure). ) is time-divided.

The timing controller transmits display information (Source Output) to each data driving IC of the panel driver during the data writing period (display), and transmits the display information (Source Output) to the panel during the touch driving period (touch). It is not transmitted to each data driver IC in the driver part.

Accordingly, the EPI signal has a data signal form during the data writing period (display) and has a clock training form during the touch driving period (touch).

However, the driving current (Tx/Rx Current) of the transmission/reception buffer has a default value for both the data writing period (display) and the touch driving period (touch).

Since the EPI signal has a data signal form (worst case) during the data writing period (display), the driving current (Tx/Rx Current) of the transmission/reception buffer requires a default value, which causes a major problem in power consumption. However, the EPI signal has a clock training form during the touch driving period, and the clock training signal has a shorter number of toggling and a shorter period than the data signal form. Because it is long, it can be driven with low current. Nevertheless, because the driving current (Tx/Rx Current) of the transmission/reception buffer has a default value even during the touch driving period (touch), there is a problem in that power consumption is wasted.

The purpose of the present invention is to reduce power consumption of a touch display device by driving the transmission/reception buffer with a driving current lower than a default value during the touch driving period.

A touch display device according to the present invention for achieving the above object includes a timing controller and a plurality of touch/data ICs, and the timing controller and the plurality of touch/data ICs are connected through an EPI interface transmission line. In the touch display device, the timing controller includes a transmitter to transmit display information to each of the plurality of touch/data ICs through the EPI interface transmission line, and each of the plurality of touch/data ICs has the EPI interface. It has a receiving unit for receiving the display information through a transmission line, and the transmitting unit of the timing controller or the receiving unit of each touch/data IC is driven with a first driving current during the data writing period, and the first driving current is driven during the touch driving period. It is characterized by being driven with a second driving current that is lower than the first driving current.

Here, the transmitting unit or the receiving unit includes a first driving current supply unit that supplies the first driving current, a second driving current supply unit that supplies the second driving current, and the first driving current supply unit according to the touch synchronization signal. A switching unit that selects and outputs one of the first driving current and the second driving current of the second driving current supply unit, and a transmitting buffer or receiving buffer driven by the current selected by the switching unit. do.

The first driving current supply unit or the second driving current supply unit includes a first current mirror unit that mirrors a constant voltage to supply a drive current to the transmission buffer or the reception buffer, and a reference current source to mirror the first current mirror unit. It is characterized by comprising a second current mirror unit for controlling and a setting unit that sets the driving current supplied from the first current mirror unit to be greater than or equal to the current mirrored by the second current mirror unit.

The first driving current supply unit and the second driving current supply unit have the same circuit configuration, and the first driving current supply unit outputs a larger current than the second driving current supply unit by the setting unit. Do it as

In the setting unit, a plurality of transistors outputting different current values are connected in parallel between a node to which the first current mirror unit and the second current mirror unit are connected and a ground terminal, and a plurality of switches that respectively switch the plurality of transistors. It is characterized by having a.

In addition, a method of driving a touch display device according to the present invention for achieving the above object includes a timing controller and a plurality of touch/data ICs, and an EPI interface between the timing controller and the plurality of touch/data ICs. Connected through a transmission line, the timing controller has a transmitter, and each of the plurality of touch/data ICs has a receiver. In the method of driving a touch display device, the transmitter of the timing controller or each touch/data IC The receiver is driven with a first driving current during the data writing period, and is driven with a second driving current lower than the first driving current during the touch driving period.

The touch display device and its driving method according to an embodiment of the present invention having the above features have the following effects.

That is, during the data writing period, the transmission/reception buffer is driven with a current of a default value, and during the touch driving period, the transmission/reception buffer is driven with a current lower than the driving current during the data writing period, thereby reducing power consumption.

Additionally, during the data writing period, the transmission/reception buffer is driven with a current of a default value, and during the touch driving period, the transmission/reception buffer is driven with a current lower than the driving current during the data writing period, thereby reducing power consumption.

In addition, the circuit of the first driving current supply unit for supplying a driving current to the transmission buffer or the reception buffer during the data writing period and the second driving current supply unit for supplying the driving current to the transmission buffer or the reception buffer during the touch driving period are configured in the same manner. And since the driving current can be set differently through the setting unit, it can be driven with various options.

1 is a waveform diagram of display information (Source output), EPI signal (EPI Signal), and driving current (Tx/Rx Current) of a transmission/reception buffer during a conventional data writing period.
Figure 2 is a block diagram schematically showing the configuration of a touch display device according to an embodiment of the present invention.
Figure 3 is a schematic configuration diagram of the transmitting unit (Tx) of the timing controller or the receiving unit of each touch/data IC according to the present invention.
FIG. 4 is a circuit diagram of the first or second driving current supply unit of FIG. 3.
FIG. 5 is a circuit diagram of the transmission buffer or reception buffer of FIG. 3.
Figure 6 is a waveform diagram of display information (Source output), EPI signal (EPI Signal), and driving current (Tx/Rx Current) of the transmission/reception buffer during the data writing period according to the present invention.
Figure 7 is a waveform diagram of the vertical synchronization signal (Vsync), the touch synchronization signal (Tsync), the driving current (Tx Current) of the transmitting unit (Tx), and the driving current (Rx Current) of the receiving unit (Rx) according to the present invention.
8 shows the driving current (Tx Current) of the transmitting unit (Tx) and the driving current (Rx) of the receiving unit (Rx) during the data writing period (display) and the touch driving period (touch) with various options according to the present invention. This is a table setting Rx Current.
FIG. 9 is a waveform diagram showing a change in driving current (Tx Current) of the transmitter (Tx) during the data writing period (display) and the touch driving period (touch) according to FIG. 8.
FIG. 10 is a waveform diagram showing a change in driving current (Rx Current) of the receiving unit (Rx) during the data writing period (display) and the touch driving period (touch) according to FIG. 8.

The touch display device and its driving method of a preferred embodiment of the present invention having the above features will be described in more detail with reference to the attached drawings as follows.

FIG. 2 is a block diagram schematically showing the configuration of a touch display device according to an embodiment of the present invention, and FIG. 3 is a schematic configuration of a transmitting unit (Tx) of a timing controller or a receiving unit of each touch/data IC according to the present invention. It is also a degree.

2 and 3, the touch display device according to the present invention includes a timing controller (TCON), a plurality of touch/data ICs (TD-IC1, TD-IC2, TD-IC3, TD-IC4), and a display panel ( PANEL), etc.

Each of the plurality of touch/data ICs (TD-IC1 to TD-IC4) is mounted on a circuit film such as TCP (Tape Carrier Package), COF (Chip On Film), FPC (Flexible Print Circuit), etc. to form a display panel (PANEL). And the timing controller (TCON) is attached to the PCB (not shown in the drawing) on which it is mounted using the TAB (Tape Automatic Bonding) method, or is mounted on the panel 500 using the COG (Chip On Glass) method to connect the PCB and the FPC. can be connected through

The display panel (PANEL) has touch and display functions, displays images through a pixel array in which pixels are arranged in a matrix, and senses whether or not a touch is being touched using a capacitance method using a touch electrode that also serves as a common electrode.

The display panel may be an organic light emitting diode display panel or a liquid crystal display panel.

In addition, in order to write image data to pixels in a time division manner and sense whether or not a touch is touched by touch electrodes, a connection is made between the timing controller (TCON) and each of the plurality of touch/data ICs (TD-IC1 to TD-IC4). It is connected via an EPI interface transmission line.

In this way, in order to transmit image data from the timing controller (TCON) to each of the plurality of touch/data ICs (TD-IC1 to TD-IC4) through the EPI interface transmission line, the timing controller (TCON) includes a transmitter ( Tx) is provided, and each of the plurality of touch/data ICs (TD-IC1 to TD-IC4) is provided with a receiving unit (Rx).

Of course, although not shown in the drawing, during the touch driving period, touch voltage information, etc. is transmitted from each of the plurality of touch/data ICs (TD-IC1 to TD-IC4) to the timing controller (TCON) through the EPI interface transmission line. In order to transmit, each of the plurality of touch/data ICs (TD-IC1 to TD-IC4) is provided with a transmitter (Tx), and the timing controller (TCON) is provided with a receiver (Rx).

In the present invention, the purpose of the present invention is to reduce power consumption when transmitting image data from the timing controller (TCON) to each of the touch/data ICs (TD-IC1 to TD-IC4), so the transmitter (Tx) of the timing controller (TCON) And only the receiving unit (Rx) of each touch/data IC is shown.

The transmitting unit (Tx) of the timing controller and the receiving unit of each touch/data IC have the same configuration as shown in FIG. 3.

That is, as shown in FIG. 3, the transmitting unit (Tx) of the timing controller or the receiving unit of each touch/data IC includes a first driving current supply unit (1) that supplies driving current to the transmitting buffer or the receiving buffer during the data writing period. ), a second driving current supply unit 2 that supplies a driving current to the transmission buffer or receiving buffer during the touch driving period, and a current output from the first driving current supply unit 1 according to the touch synchronization signal Tsync, and A switching unit (SW1, SW2) that selects and outputs one of the currents output from the second driving current supply unit (2), and a transmitting buffer or receiving buffer driven by the current selected by the switching units (SW1, SW2) It is composed of (3).

The first switching element (SW1) of the switching units (SW1, SW2) is an N-type switching element, and the second switching element (SW2) is a P-type switching element. Therefore, the switching units (SW1, SW2) select and output the current output from the first driving current supply unit (1) in the high logic period (data writing period) of the touch synchronization signal (Tsync), and output the touch synchronization signal. In the low logic section (touch driving period) of the signal Tsync, the current output from the second driving current supply unit 2 is selected and output.

In the above, the second driving current supply unit 2 is set to output a lower current than the first driving current supply unit 1.

Meanwhile, the configuration of the first and second driving current supply units is as shown in FIG. 4.

FIG. 4 is a circuit diagram of the first or second driving current supply unit of FIG. 3.

The first driving current supply unit 1 and the second driving current supply unit 2 have the same circuit configuration.

That is, as shown in FIG. 4, the first current mirror unit is composed of first and second transistors T1 and T2 and supplies a driving current to the transmission buffer or reception buffer 3 by mirroring the constant voltage (VCC). (11), a second current mirror unit 12 consisting of third and fourth transistors T3 and T4 and controlling the mirroring value of the first current mirror unit 11 by mirroring the reference current source; It is provided with first to third switches (SW1 to SW3) and fifth to seventh transistors (T5, T6, T7) having different output currents, depending on the selection of the first to third switches (SW1 to SW3). Setting the current (Tx or Rx Current) output to the transmission buffer or reception buffer 3 through the first current mirror unit 11 to be greater than or equal to the mirroring current of the second current mirror unit 12. It is comprised of a setting unit (13).

Here, the setting unit 13 is between the first switch SW1 and the ground terminal (GND) and the N node to which the first current mirror unit 11 and the second current mirror unit 12 are connected. The fifth transistor (T5) is connected in series, the second switch (SW2) and the sixth transistor (T6) are connected in series, the second switch (SW3) and the seventh transistor (T7) are connected in series, and the second switch (SW3) and the seventh transistor (T7) are connected in series. The fifth to seventh transistors T5, T6, and T7 are connected in parallel with each other.

The fifth to seventh transistors (T5, T6, T7) of the setting unit 13 output lower current than the third and fourth transistors (T3, T4) of the second current mirror unit 12, The fifth transistor T5 outputs the lowest current, and the sixth transistor T6 outputs a current higher than the fifth transistor T5 and lower than the seventh transistor T7.

For example, assuming that the third and fourth transistors T3 and T4 of the second current mirror unit 12 output a current of k value, the fifth transistor T5 outputs a current of k × 0.1. The sixth transistor (T6) outputs a current of k×0.2, and the seventh transistor (T7) outputs a current of k×0.3.

Therefore, when the reference current (Iref) is 2mA, the first switch (SW1) is turned off and the second and third switches (SW2, SW3) are turned on, the first current mirror unit 11 A current of 3mA is supplied to the transmit buffer or receive buffer (3) (2 + 0.4 + 0.6 = 3).

Meanwhile, when the reference current (Iref) is 2mA and the first to third switches (SW1, SW2, and SW3) are all turned off, the first current mirror unit 11 transmits the transmit buffer or the receive buffer (3). ) is supplied with a current of 2mA.

Accordingly, the first driving current supply unit 1 and the second driving current supply unit 2 have the same circuit configuration, but the first driving current supply unit 1 has the reference current Iref of 2 mA. When the first switch (SW1) is turned off and the second and third switches (SW2, SW3) are set to turn on, a current of 3 mA is output.

Conversely, when the second driving current supply unit 2 sets all of the first to third switches SW1, SW2, and SW3 to turn off when the reference current Iref is 2 mA, the first driving current Outputs a current of 2 mA, which is lower than that of the supply unit (1).

Figure 5 is a circuit diagram of the transmission buffer or reception buffer of Figure 3.

As shown in FIG. 5, the transmitting buffer or receiving buffer according to the present invention transmits the current selected by the switching units (SW1, SW2) to the eighth and ninth transistors controlled by the EPI+ signal and the EPI- signal, respectively. It is composed of (T11, T12), and 10th and 11th transistors (T13, T14) that mirror the current of the 8th transistor (T11) and output (OUT).

The driving method (operation) of the touch display device according to the present invention configured as described above will be described as follows.

Figure 6 is a waveform diagram of display information (Source output), EPI signal (EPI Signal), and driving current (Tx/Rx Current) of the transmission/reception buffer during the data writing period according to the present invention.

In order to transmit display information and touch voltage information through the EPI interface transmission line in a time division manner, the data writing period (display) and the touch driving period (touch) are determined by a touch synchronization signal (Tsync, not shown in the drawing). ) is time-divided.

The timing controller (TCON) transmits display information (Source Output) to the plurality of touch/data ICs (TD-IC1, TD-IC2, TD-IC3, TD-IC4) during the data writing period (display). , During the touch driving period (touch), the display information (Source Output) is not transmitted to the plurality of touch/data ICs (TD-IC1, TD-IC2, TD-IC3, TD-IC4).

Accordingly, the EPI signal has a data signal form during the data writing period (display) and has a clock training form during the touch driving period (touch).

The EPI signal has a clock training form during the touch driving period, and the clock training signal has a shorter number of toggling and a longer cycle than the data signal form, so the EPI signal has a low frequency. It can be driven with low current.

Accordingly, the driving current (Tx/Rx Current) of the transmission/reception buffer has a lower value during the touch driving period (touch) than during the data writing period (display).

This is explained in detail as follows.

Figure 7 is a waveform diagram of the vertical synchronization signal (Vsync), the touch synchronization signal (Tsync), the driving current (Tx Current) of the transmitting unit (Tx), and the driving current (Rx Current) of the receiving unit (Rx) according to the present invention.

Generally, there are 16 LHBs (Long Horizontal Blank, Touch sensing sections) during one frame.

Therefore, as described above, assuming that the first driving current supply unit 1 is set to output a current of 3 mA and the second driving current supply unit 2 is set to output a current of 2 mA, in FIG. 3 As shown, since the switching units (SW1, SW2) are controlled by the touch synchronization signal, the driving current (Tx Current) of the transmitting unit (Tx) and the driving current (Rx Current) of the receiving unit (Rx) are It has a current value of 3mA during the data writing period (display), and has a current value of 2mA during the touch driving period (touch).

In this way, according to the model and resolution of the touch display device, by adjusting the number of transistors and the reference current (Iref) of the setting unit 13 in FIG. 4, various options are available for the data writing period (display) and the touch driving. The driving current (Tx Current) of the transmitting unit (Tx) and the driving current (Rx Current) of the receiving unit (Rx) during the period (touch) can be set.

8 shows the driving current (Tx Current) of the transmitting unit (Tx) and the driving current (Rx) of the receiving unit (Rx) during the data writing period (display) and the touch driving period (touch) with various options according to the present invention. It is a table setting Rx Current, and FIG. 9 is a waveform showing the change in driving current (Tx Current) of the transmitter (Tx) during the data writing period (display) and the touch driving period (touch) according to FIG. 8. 10 is a waveform diagram showing a change in driving current (Rx Current) of the receiving unit (Rx) during the data writing period (display) and the touch driving period (touch) according to FIG. 8.

8 to 10, the output current of the first driving current supply unit 1, which is the driving current of the transmitting unit Tx, during the data writing period (display) is set to 3 mA, and the touch driving period (touch) During the data writing period (display), the output current of the second driving current supply unit 2, which is the driving current of the transmitting unit (Tx), is set to 2 mA, and the first driving current, which is the driving current of the receiving unit (Rx), is set to 2 mA during the data writing period (display). The output current of the supply unit 1 may be set to 8 mA, and the output current of the second driving current supply unit 2, which is the driving current of the receiver Rx during the touch driving period (touch), may be set to 7 mA.

The driving current value during the touch driving period (touch) is not automatically set, and it is necessary to confirm and set the minimum value according to experiment.

Therefore, the transmission/reception driving current can be reduced during the LHB (Touch sensing section), and the reduction in transmission/reception driving current increases as the number of EPI interface transmission lines increases, the higher the speed, and the LHB section increases.

For example, the driving current of the transmitter is such that the difference between the driving current during the data writing period and the driving current during the touch driving period is 1 mA, the number of EPI interface transmission lines is 16, the driving voltage is 1 V, and the touch driving is performed in 1 frame. When the period ratio is 2, 8mW can be saved (1mA × 16 × 1V)/2 = 8mW).

In addition, the driving current of the receiver has a difference between the driving current during the data writing period and the driving current during the touch driving period of 1 mA, the number of EPI interface transmission lines is 16, the driving voltage is 1.8 V, and the touch driving period in 1 frame. When the ratio is 2, 14.4mW can be reduced (1mA × 16 × 1.8V)/2 = 14.4mW).

Therefore, under the above conditions, a total power consumption of 22.4 mW can be reduced.

The above description is merely an exemplary description of the present invention, and various modifications may be made by those skilled in the art without departing from the technical spirit of the present invention. Accordingly, the embodiments disclosed in the specification of the present invention do not limit the present invention. The scope of the present invention should be interpreted in accordance with the scope of the patent claims below, and all technologies within the equivalent scope thereof should be interpreted as being included in the scope of the present invention.

1: first driving current supply unit 2: second driving current supply unit
3: Transmit or receive buffer 11, 12: Current mirror unit
13: Setting section

Claims (6)

A touch display device comprising a timing controller and a plurality of touch/data ICs, wherein the timing controller and the plurality of touch/data ICs are connected through an EPI interface transmission line,
The timing controller includes a transmitter to transmit display information to each of the plurality of touch/data ICs through the EPI interface transmission line, and each of the plurality of touch/data ICs transmits the display information to each of the plurality of touch/data ICs through the EPI interface transmission line. Equipped with a receiving unit for receiving,
The transmitting unit of the timing controller or the receiving unit of each touch/data IC is driven with a first driving current during the data writing period, and is driven with a second driving current lower than the first driving current during the touch driving period,
The transmitting unit or receiving unit,
a first driving current supply unit that supplies the first driving current;
a second driving current supply unit that supplies the second driving current;
a switching unit that selects and outputs one of a first driving current of the first driving current supply unit and a second driving current of the second driving current supply unit according to a touch synchronization signal;
A touch display device including a transmission buffer or a reception buffer driven by a current selected by the switching unit. delete In claim 1,
The first driving current supply unit or the second driving current supply unit,
a first current mirror unit that mirrors the constant voltage to supply a driving current to the transmission buffer or reception buffer;
a second current mirror unit that controls mirroring of the first current mirror unit by mirroring a reference current source;
A touch display device comprising a setting unit that sets the driving current supplied from the first current mirror unit to be greater than or equal to the current mirrored by the second current mirror unit. In claim 3,
The first driving current supply unit and the second driving current supply unit have the same circuit configuration, and the first driving current supply unit outputs a larger current than the second driving current supply unit by the setting unit. Device. In claim 3,
In the setting unit, a plurality of transistors outputting different current values are connected in parallel between a node to which the first current mirror unit and the second current mirror unit are connected and a ground terminal, and a plurality of switches that respectively switch the plurality of transistors. A touch display device having a. A timing controller and a plurality of touch/data ICs are connected, and the timing controller and the plurality of touch/data ICs are connected through an EPI interface transmission line. The timing controller includes a transmitter, and the plurality of touch/data ICs are connected to each other through an EPI interface transmission line. In the method of driving a touch display device where each IC has a receiving unit,
The transmitting unit of the timing controller or the receiving unit of each touch/data IC is driven with a first driving current during the data writing period, and is driven with a second driving current lower than the first driving current during the touch driving period,
The transmitting unit or receiving unit,
a first driving current supply unit that supplies the first driving current;
a second driving current supply unit that supplies the second driving current;
a switching unit that selects and outputs one of a first driving current of the first driving current supply unit and a second driving current of the second driving current supply unit according to a touch synchronization signal;
A method of driving a touch display device including a transmission buffer or a reception buffer driven by a current selected by the switching unit.