Charge pump, touch drive unit, and display device

Abstract

The invention relates to a charge pump, a touch driving part and a display device. The charge pump includes: a 2-1 switch including a first electrode to which a first voltage is applied and a second electrode connected to a 2-1 node; a 2-2 switch including a first electrode connected to the 2-2 node and a second electrode connected to ground; a second-third switch including a first electrode connected to the second-1 node and a second electrode connected to ground; a 2-4 switch including a first electrode connected to the 2-2 node and a second electrode connected to the 2-3 node; a 2-1 capacitor including a first electrode connected to the 2-1 node and a second electrode connected to the 2-2 node; a 2-2 capacitor including a first electrode connected to the 2-3 node and a second electrode connected to ground; a first transfer switch including a first electrode to which a power supply voltage is applied and a second electrode connected to the 2-1 node; and a second transfer switch including a first electrode to which a power supply voltage is applied and a second electrode connected to the 2-2 node.

Description

Technical Field

[0001] The present invention relates to a charge pump, a touch driving unit including the charge pump, and a display device including the touch driving unit, and relates to a charge pump, a touch driving unit including the charge pump, and a display device including the touch driving unit that can cope with heavy loads, can reduce power consumption, and can reduce electromagnetic interference (EMI: Electro Magnetic Interference). Background Art

[0002] In the case of electronic devices mounted on an automobile, compared with other frequency regions, the EMI radiation reference in the long wave and middle wave frequency regions is set very strictly, and in an automotive display including a touch function, the EMI radiation generated in the touch unit and the display unit is added together, so it may be more difficult to meet international standards.

[0003] Since the radiation noise in the long wave and middle wave frequency bands is mainly caused by the touch driving voltage, in the case of applying an external solution such as an EMI shielding film, there is a problem that the touch function cannot be operated. Therefore, a method for reducing EMI caused by touch driving may be required.

[0004] In the case of a square wave signal used in a touch driving circuit of the prior art, since harmonic frequency peaks are generated, it may be more difficult to improve EMI. Therefore, as described in the automotive display, when the EMI reference is strict, a sine wave signal needs to be used as the touch driving signal. Summary of the Invention

[0005] Accordingly, the technical problem of the present invention is proposed in view of the above problems, and the object of the present invention is to provide a charge pump that can cope with heavy loads, can reduce power consumption, and can reduce electromagnetic interference (EMI: ElectroMagnetic Interference).

[0006] Another object of the present invention is to provide a touch driving unit including the charge pump.

[0007] Another object of the present invention is to provide a display device including the touch driving unit.

[0008] To achieve the above object of the present invention, a charge pump according to an embodiment includes a 2-1 switch, a 2-2 switch, a 2-3 switch, a 2-4 switch, a 2-1 capacitor, a 2-2 capacitor, a first conversion switch, and a second conversion switch. The 2-1 switch includes a first electrode to which a first voltage is applied and a second electrode connected to a 2-1 node. The 2-2 switch includes a first electrode connected to a 2-2 node and a second electrode connected to ground. The 2-3 switch includes a first electrode connected to the 2-1 node and a second electrode connected to the ground. The 2-4 switch includes a first electrode connected to the 2-2 node and a second electrode connected to a 2-3 node. The 2-1 capacitor includes a first electrode connected to the 2-1 node and a second electrode connected to the 2-2 node. The 2-2 capacitor includes a first electrode connected to the 2-3 node and a second electrode connected to the ground. The first conversion switch includes a first electrode to which a power supply voltage is applied and a second electrode connected to the 2-1 node. The second conversion switch includes a first electrode to which the power supply voltage is applied and a second electrode connected to the 2-2 node.

[0009] In an embodiment of the present invention, in the 2-1 operation, the 2-1 switch and the 2-2 switch may be turned on, and the 2-3 switch, the 2-4 switch, the first conversion switch, and the second conversion switch may be turned off.

[0010] In an embodiment of the present invention, in the 2-2 operation, the 2-3 switch and the 2-4 switch may be turned on, and the 2-1 switch, the 2-2 switch, the first conversion switch, and the second conversion switch may be turned off.

[0011] In an embodiment of the present invention, in the 2-3 operation, the second conversion switch and the 2-3 switch may be turned on, and the 2-1 switch, the 2-2 switch, the 2-4 switch, and the first conversion switch may be turned off.

[0012] In an embodiment of the present invention, in the 2-4 operation, the first conversion switch and the 2-4 switch may be turned on, and the 2-1 switch, the 2-2 switch, the 2-3 switch, and the second conversion switch may be turned off.

[0013] In order to achieve the above object of the present invention, a touch driving unit according to an embodiment includes a first charge pump, a second charge pump, a path switch, and a signal generation unit. The first charge pump receives a power supply voltage and outputs a first voltage. The second charge pump receives the power supply voltage and the first voltage and outputs a second voltage. The path switch includes a first electrode connected to an output end of the first charge pump and a second electrode connected to an output end of the second charge pump. The signal generation unit includes a first input end connected to the output end of the first charge pump and a second input end connected to the output end of the second charge pump.

[0014] In an embodiment of the present invention, in a first mode, the path switch may be turned off, the first voltage may be applied to the first input end of the signal generation unit, and the second voltage may be applied to the second input end of the signal generation unit.

[0015] In an embodiment of the present invention, in a second mode, the path switch may be turned on, the first voltage may be applied to the first input end of the signal generation unit, and the second voltage may be applied to the first input end of the signal generation unit.

[0016] In an embodiment of the present invention, the second charge pump may include: a 2-1 switch, including a first electrode to which the first voltage is applied and a second electrode connected to a 2-1 node; a 2-2 switch, including a first electrode connected to a 2-2 node and a second electrode connected to ground; a 2-3 switch, including a first electrode connected to the 2-1 node and a second electrode connected to ground; a 2-4 switch, including a first electrode connected to the 2-2 node and a second electrode connected to a 2-3 node; a 2-1 capacitor, including a first electrode connected to the 2-1 node and a second electrode connected to the 2-2 node; a 2-2 capacitor, including a first electrode connected to the 2-3 node and a second electrode connected to ground; a first conversion switch, including a first electrode to which the power supply voltage is applied and a second electrode connected to the 2-1 node; and a second conversion switch, including a first electrode to which the power supply voltage is applied and a second electrode connected to the 2-2 node.

[0017] In an embodiment of the present invention, in a 2-1 operation, the 2-1 switch and the 2-2 switch may be turned on, the 2-3 switch, the 2-4 switch, the first conversion switch, and the second conversion switch may be turned off, and the path switch may be turned off.

[0018] In an embodiment of the present invention, in the 2-2 operation, the 2-3 switch and the 2-4 switch may be turned on, the 2-1 switch, the 2-2 switch, the first conversion switch, and the second conversion switch may be turned off, and the path switch may be turned off.

[0019] In an embodiment of the present invention, in the 2-3 operation, the second conversion switch and the 2-3 switch may be turned on, the 2-1 switch, the 2-2 switch, the 2-4 switch, and the first conversion switch may be turned off, and the path switch may be turned off.

[0020] In an embodiment of the present invention, in the 2-4 operation, the first conversion switch and the 2-4 switch may be turned on, the 2-1 switch, the 2-2 switch, the 2-3 switch, and the second conversion switch may be turned off, and the path switch may be turned on.

[0021] In an embodiment of the present invention, the first charge pump may include: a 1-1 switch including a first electrode to which the power supply voltage is applied and a second electrode connected to a 1-2 node; a 1-2 switch including a first electrode connected to a 1-1 node and a second electrode connected to ground; a 1-3 switch including a first electrode to which the power supply voltage is applied and a second electrode connected to the 1-1 node; a 1-4 switch including a first electrode connected to the 1-2 node and a second electrode connected to a 1-3 node; a 1-1 capacitor including a first electrode connected to the 1-1 node and a second electrode connected to the 1-2 node; and a 1-2 capacitor including a first electrode connected to the 1-3 node and a second electrode connected to ground.

[0022] In an embodiment of the present invention, in the 1-1 operation, the 1-1 switch and the 1-2 switch may be turned on, and the 1-3 switch and the 1-4 switch may be turned off.

[0023] In an embodiment of the present invention, in the 1-2 operation, the 1-3 switch and the 1-4 switch may be turned on, and the 1-1 switch and the 1-2 switch may be turned off.

[0024] In an embodiment of the present invention, the touch driving unit may further include: a multiplexer connected to the signal generating unit. The multiplexer may be connected to the transmission electrode of the touch panel.

[0025] To achieve the above object of the present invention, a display device according to an embodiment includes: a display panel, a display panel driving unit, a touch panel, and a touch driving unit. The display panel driving unit drives the display panel. The touch panel is disposed on the display panel. The touch driving unit drives the touch panel. The touch driving unit includes: a first charge pump that receives a power supply voltage and outputs a first voltage; a second charge pump that receives the power supply voltage and the first voltage and outputs a second voltage; a path switch including a first electrode connected to an output terminal of the first charge pump and a second electrode connected to an output terminal of the second charge pump; and a signal generation unit including a first input terminal connected to the output terminal of the first charge pump and a second input terminal connected to the output terminal of the second charge pump.

[0026] In an embodiment of the present invention, the second charge pump may include: a 2-1 switch including a first electrode to which the first voltage is applied and a second electrode connected to a 2-1 node; a 2-2 switch including a first electrode connected to a 2-2 node and a second electrode connected to ground; a 2-3 switch including a first electrode connected to the 2-1 node and a second electrode connected to the ground; a 2-4 switch including a first electrode connected to the 2-2 node and a second electrode connected to the 2-3 node; a 2-1 capacitor including a first electrode connected to the 2-1 node and a second electrode connected to the 2-2 node; a 2-2 capacitor including a first electrode connected to the 2-3 node and a second electrode connected to the ground; a first conversion switch including a first electrode to which the power supply voltage is applied and a second electrode connected to the 2-1 node; and a second conversion switch including a first electrode to which the power supply voltage is applied and a second electrode connected to the 2-2 node.

[0027] The first charge pump may include: a 1-1 switch including a first electrode to which the power supply voltage is applied and a second electrode connected to a 1-2 node; a 1-2 switch including a first electrode connected to a 1-1 node and a second electrode connected to ground; a 1-3 switch including a first electrode to which the power supply voltage is applied and a second electrode connected to the 1-1 node; a 1-4 switch including a first electrode connected to the 1-2 node and a second electrode connected to a 1-3 node; and a 1-1 capacitor including a first electrode connected to the 1-1 node and a second electrode connected to the 1-2 node; and a 1-2 capacitor including a first electrode connected to the 1-3 node and a second electrode connected to the ground.

[0028] According to one embodiment, a touch driving unit may include: a first charge pump that receives a power supply voltage and outputs a first voltage; a second charge pump that outputs a second voltage in a first mode and outputs a third voltage in a second mode; a path switch connected between an output terminal of the first charge pump and an output terminal of the second charge pump; and a signal generation unit including a first input terminal connected to the output terminal of the first charge pump and a second input terminal connected to the output terminal of the second charge pump. Wherein, in the first mode, the second charge pump may output the second voltage through the output terminal of the second charge pump based on the first voltage output from the first charge pump, and the path switch may be turned off so that the second voltage is input to the second input terminal of the signal generation unit. Wherein, in the second mode, the second charge pump may output the third voltage through the output terminal of the second charge pump based on the power supply voltage, and the path switch may be turned on so that the third voltage is input to the first input terminal of the signal generation unit.

[0029] In an embodiment of the present invention, the second voltage may correspond to a negative value of the first voltage, and the third voltage may correspond to the first voltage.

[0030] According to the charge pump as described above, the touch driving unit including the charge pump, and the display device including the touch driving unit, in the case of a positive swing that requires a heavy load, the second charge pump can be converted from a negative charge pump to a positive charge pump to cope with the heavy load, thereby improving the reliability of the touch driving unit.

[0031] In addition, since the second charge pump is converted from a negative charge pump to a positive charge pump, it is possible to prevent the sine wave from being distorted due to the insufficient capacity of the first charge pump and the deterioration of EMI caused by the distortion. Therefore, the EMI of the display device can be reduced.

[0032] In addition, because the second charge pump is converted from a negative charge pump to a positive charge pump, the current flowing to the first charge pump can be reduced, thereby reducing the power consumption of the touch driving unit. Brief Description of the Drawings

[0033] Figure 1 is a block diagram showing a display device according to an embodiment of the present invention.

[0034] Figure 2 is a diagram showing Figure 1 a block diagram of the display panel and the display panel driving unit.

[0035] Figure 3 is a diagram showing Figure 1Block diagram of the touch panel and touch drive unit.

[0036] Figure 4 Shows Figure 1 Circuit diagram of the touch drive unit.

[0037] Figure 5 Shows the Figure 4 Operation of the touch drive unit in the first mode.

[0038] Figure 6 Shows the Figure 4 Operation of the touch drive unit in the second mode.

[0039] Figure 7 Shows Figure 4 Circuit diagram of the first charge pump.

[0040] Figure 8 Shows Figure 7 Operation 1-1 of the first charge pump.

[0041] Figure 9 Shows Figure 7 Operation 1-2 of the first charge pump.

[0042] Figure 10 Shows Figure 4 Circuit diagram of the second charge pump and path switch.

[0043] Figure 11 Shows Figure 10 Operation 2-1 of the second charge pump.

[0044] Figure 12 Shows Figure 10 Operation 2-2 of the second charge pump.

[0045] Figure 13 Shows Figure 10 Operation 2-3 of the second charge pump.

[0046] Figure 14 Shows Figure 10 Operation 2-4 of the second charge pump.

[0047] Figure 15 Waveform diagram of the input voltage and touch drive signal of the signal generation unit according to the comparative example during heavy load positive swing.

[0048] Figure 16 Waveform diagram of the input voltage and touch drive signal of the signal generation unit according to this embodiment during heavy load positive swing.

[0049] Figure 17 is a cross-sectional view showing an example of a display device Figure 1 .

[0050] Figure 18 is a block diagram showing an electronic device according to an embodiment of the present invention.

[0051] Figure 19 is a view showing an example in which the Figure 18 electronic device is implemented as a smart phone.

[0052] Figure 20 is a view showing an example in which the Figure 18 electronic device is implemented as a vehicle display.

[0053] Description of Reference Numerals 100: Display panel 200: Display panel driving unit 220: Driving control unit 240: Gate driving unit 260: Gamma reference voltage generation unit 280: Data driving unit 300: Touch panel 400: Touch driving unit Detailed Description

[0054] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

[0055] Figure 1 is a block diagram showing a display device according to an embodiment of the present invention. Figure 2 is a view showing Figure 1 the display panel 100 and the display panel driving unit 200. Figure 3 is a view showing Figure 1 the touch panel 300 and the touch driving unit 400.

[0056] Referring to Figures 1 to 3 , the display device includes a display panel 100, a display panel driving unit 200, a touch panel 300, and a touch driving unit 400.

[0057] The display panel 100 displays an image. The display panel driving unit 200 drives the display panel 100.

[0058] The touch panel 300 senses a touch event. The touch panel 300 may be disposed on the display panel 100. The touch driving unit 400 drives the touch panel 300.

[0059] In an embodiment of the present invention, the display panel 100 and the touch panel 300 may be integrally formed. In an embodiment of the present invention, the display panel driving unit 200 and the touch driving unit 400 may be integrally formed.

[0060] The display panel driving unit 200 includes a driving control unit 220, a gate driving unit 240, a gamma reference voltage generating unit 260, and a data driving unit 280.

[0061] For example, the driving control unit 220 and the data driving unit 280 may be integrally formed. For example, the driving control unit 220, the gamma reference voltage generating unit 260, and the data driving unit 280 may be integrally formed. A driving module formed by at least the driving control unit 220 and the data driving unit 280 integrally may be named a Timing Controller Embedded Data Driver (TED).

[0062] The display panel 100 includes a display unit AA for displaying an image and a peripheral unit PA disposed adjacent to the display unit AA.

[0063] The display panel 100 includes a plurality of gate lines GL, a plurality of data lines DL, and a plurality of pixels P electrically connected to the gate lines GL and the data lines DL respectively. The gate lines GL may extend along a first direction D1, and the data lines DL may extend along a second direction D2 intersecting the first direction D1.

[0064] The driving control unit 220 receives input image data IMG and an input control signal CONT from an external device (e.g., an application processor). For example, the input image data IMG may include red image data, green image data, and blue image data. The input image data IMG may include white image data. The input image data IMG may include magenta image data, yellow image data, and cyan image data. The input control signal CONT may include a main clock signal and a data enable signal. The input control signal CONT may further include a vertical synchronization signal and a horizontal synchronization signal.

[0065] The driving control unit 220 generates a gate control signal CONT1, a data control signal CONT2, a gamma control signal CONT3, and a data signal DATA based on the input image data IMG and the input control signal CONT.

[0066] The driving control unit 220 generates the gate control signal CONT1 for controlling the operation of the gate driving unit 240 based on the input control signal CONT, and outputs the gate control signal CONT1 to the gate driving unit 240. The gate control signal CONT1 may include a vertical start signal and a gate clock signal.

[0067] The driving control unit 220 generates the data control signal CONT2 for controlling the operation of the data driving unit 280 based on the input control signal CONT, and outputs the data control signal CONT2 to the data driving unit 280. The data control signal CONT2 may include a horizontal start signal and a load signal.

[0068] The driving control unit 220 generates a data signal DATA based on the input image data IMG. The driving control unit 220 outputs the data signal DATA to the data driving unit 280.

[0069] The driving control unit 220 generates the gamma control signal CONT3 for controlling the operation of the gamma reference voltage generation unit 260 based on the input control signal CONT, and outputs the gamma control signal CONT3 to the gamma reference voltage generation unit 260.

[0070] The gate driving unit 240 generates a gate signal for driving the gate line GL in response to the gate control signal CONT1 received from the driving control unit 220. The gate driving unit 240 outputs the gate signal to the gate line GL. For example, the gate driving unit 240 may sequentially output the gate signal to the gate line GL. For example, the gate driving unit 240 may be mounted on the peripheral portion PA of the display panel 100. For example, the gate driving unit 240 may be integrated on the peripheral portion PA of the display panel 100.

[0071] The gamma reference voltage generation unit 260 generates a gamma reference voltage VGREF in response to the gamma control signal CONT3 input from the driving control unit 220. The gamma reference voltage generation unit 260 provides the gamma reference voltage VGREF to the data driving unit 280.

[0072] In an embodiment of the present invention, the gamma reference voltage generation unit 260 may be disposed within the driving control unit 220 or may be disposed within the data driving unit 280.

[0073] The data driving unit 280 receives the data control signal CONT2 and the data signal DATA from the driving control unit 220, and receives the gamma reference voltage VGREF from the gamma reference voltage generation unit 260. The data driving unit 280 uses the gamma reference voltage VGREF to convert the data signal DATA into an analog data voltage. The data driving unit 280 outputs the data voltage to the data line DL.

[0074] The touch panel 300 may include a plurality of transmitting electrodes TX1, TX2 and a plurality of receiving electrodes RX1, RX2.

[0075] For example, the transmitting electrodes TX1, TX2 may include a plurality of electrode portions arranged along the second direction D2 and a plurality of connection portions connecting the electrode portions. The transmitting electrodes TX1, TX2 may be connected to the transmission lines TL1, TL2. The transmission lines TL1, TL2 may extend along the first direction D1.

[0076] For example, the receiving electrodes RX1, RX2 may include a plurality of electrode portions arranged along the first direction D1 and a plurality of connection portions connecting the electrode portions. The receiving electrodes RX1, RX2 may be connected to the receiving lines RL1, RL2. The receiving lines RL1, RL2 may extend along the first direction D1.

[0077] The touch driving unit 400 may apply a touch driving signal TXS to the touch panel 300. The touch driving unit 400 may receive a touch sensing signal RXS from the touch panel 300.

[0078] The touch driving signal TXS may be applied to the transmitting electrodes TX1, TX2. For example, the touch driving signal TXS may be a sine wave signal.

[0079] Figure 4 is a circuit diagram showing Figure 1 the touch driving unit 400. Figure 5 is a circuit diagram showing the operation of Figure 4 the touch driving unit 400 in the first mode. Figure 6 is a circuit diagram showing the operation of Figure 4 the touch driving unit 400 in the second mode.

[0080] Referring to Figures 1 to 6 the touch driving unit 400 includes a first charge pump CP1, a second charge pump CP2, a path switch SW1, and a signal generation unit SG.

[0081] The first charge pump CP1 receives the power supply voltage VDD and outputs a first voltage V1. For example, the first charge pump CP1 may be a positive charge pump. For example, the power supply voltage VDD may be xV, and in this case, the first voltage V1 may be 2xV. For example, the power supply voltage VDD may be approximately 3V, and in this case, the first voltage V1 may be approximately 6V.

[0082] The second charge pump CP2 receives the power supply voltage VDD and the first voltage V1 and outputs a second voltage V2. For example, the second charge pump CP2 may be a charge pump capable of positive and negative conversion.

[0083] The second charge pump CP2 may receive the first voltage V1 in a first mode and output the second voltage V2. The first mode may be a positive-negative mode. For example, in the first mode, the first voltage V1 may be 2xV, and in this case, the second voltage V2 may be approximately -2xV. For example, in the first mode, the first voltage V1 may be approximately 6V, and in this case, the second voltage V2 may be approximately -6V.

[0084] The second charge pump CP2 may receive the power supply voltage VDD in a second mode and output the second voltage V2. The second mode may be a positive-only mode. For example, in the second mode, the power supply voltage VDD may be xV, and in this case, the second voltage V2 may be 2xV. For example, in the second mode, the power supply voltage VDD may be approximately 3V, and in this case, the second voltage V2 may be approximately 6V.

[0085] The path switch SW1 includes a first electrode connected to the output terminal of the first charge pump CP1 and a second electrode connected to the output terminal of the second charge pump CP2.

[0086] The signal generation unit SG includes a first input terminal TR1 connected to the output terminal of the first charge pump CP1 and a second input terminal TR2 connected to the output terminal of the second charge pump CP2. The signal generation unit SG may be a sine signal generation unit.

[0087] In the first mode, the path switch SW1 may be disconnected, the first voltage V1 may be applied to the first input terminal TR1 of the signal generation unit SG, and the second voltage V2 may be applied to the second input terminal TR2 of the signal generation unit SG. In the first mode, the signal generation unit SG may generate the sine signal by using the first voltage V1 with a positive value and the second voltage V2 with a negative value. When the first voltage V1 is 6V and the second voltage V2 is -6V, the signal generation unit SG may generate a sine signal that increases and decreases between 6V and -6V.

[0088] In the second mode, the path switch SW1 can be turned on, the first voltage V1 can be applied to the first input terminal TR1 of the signal generation unit SG, and the second voltage V2 can be applied to the first input terminal TR1 of the signal generation unit SG. In the second mode, the signal generation unit SG can generate the sine signal by using the first voltage V1 having a positive value and the second voltage V2 having a positive value. When the first voltage V1 is 6V and the second voltage V2 is 6V, the signal generation unit SG can generate a sine signal that increases and decreases between 6V and 0V.

[0089] The touch driving unit 400 may further include a multiplexer MX connected to the signal generation unit SG. The multiplexer MX may be connected to the transmission electrode TX of the touch panel 300.

[0090] The touch panel 300 may further include: a first touch capacitor CBT, including a first electrode connected to the transmission electrode TX and a second electrode connected to the ground; a second touch capacitor CBR, including a first electrode connected to the reception electrode RX of the touch panel 300 and a second electrode connected to the ground; and a third touch capacitor CM, including a first electrode connected to the transmission electrode TX and a second electrode connected to the reception electrode RX.

[0091] Figure 7 is a circuit diagram showing Figure 4 the first charge pump CP1. Figure 8 is a circuit diagram showing Figure 7 the 1-1 operation of the first charge pump CP1. Figure 9 is a circuit diagram showing Figure 7 the 1-2 operation of the first charge pump CP1.

[0092] Referring to Figures 1 to 9 the first charge pump CP1 may include: a 1-1 switch S11, including a first electrode to which the power supply voltage VDD is applied and a second electrode connected to the 1-2 node N12; a 1-2 switch S12, including a first electrode connected to the 1-1 node N11 and a second electrode connected to the ground; a 1-3 switch S13, including a first electrode to which the power supply voltage VDD is applied and a second electrode connected to the 1-1 node N11; and a 1-4 switch S14, including a first electrode connected to the 1-2 node N12 and a second electrode connected to the 1-3 node N13.

[0093] The first charge pump CP1 may further include: a 1-1 capacitor C11, including a first electrode connected to the 1-1 node N11 and a second electrode connected to the 1-2 node N12.

[0094] The first charge pump CP1 may further include: a 1-2 capacitor C12, including a first electrode connected to the 1-3 node N13 and a second electrode connected to the ground.

[0095] In the 1-1 operation, the 1-1 switch S11 and the 1-2 switch S12 may be turned on, and the 1-3 switch S13 and the 1-4 switch S14 may be turned off. In the 1-1 operation, the power supply voltage VDD may be charged to the 1-1 capacitor C11 through the turned-on 1-1 switch S11 and the 1-2 switch S12.

[0096] In the 1-2 operation, the 1-3 switch S13 and the 1-4 switch S14 may be turned on, and the 1-1 switch S11 and the 1-2 switch S12 may be turned off. In the 1-2 operation, the first voltage V1 may be output at the output terminal through the turned-on 1-3 switch S13 and the 1-4 switch S14.

[0097] When the 1-1 operation is performed, the power supply voltage VDD is charged to the 1-1 capacitor C11. When the 1-2 operation is performed, the power supply voltage VDD applied to the first electrode of the 1-3 switch S13 is added to the power supply voltage VDD charged to the 1-1 capacitor C11 and output from the output terminal of the first charge pump CP1. Therefore, the first charge pump CP1 may output a voltage approximately twice that of the power supply voltage VDD as the first voltage V1.

[0098] Figure 10 is a circuit diagram showing Figure 4 the second charge pump CP2 and the path switch SW1. Figure 11 is a circuit diagram showing Figure 10 the 2-1 operation of the second charge pump CP2. Figure 12 is a circuit diagram showing Figure 10 the 2-2 operation of the second charge pump CP2. Figure 13 is a circuit diagram showing Figure 10 the 2-3 operation of the second charge pump CP2. Figure 14 is a circuit diagram showing Figure 10 the 2-4 operation of the second charge pump CP2.

[0099] Referring to Figures 10 to 14, the second charge pump CP2 includes a 2-1 switch S21, a 2-2 switch S22, a 2-3 switch S23, a 2-4 switch S24, a 2-1 capacitor C21, a 2-2 capacitor C22, a first conversion switch SC1, and a second conversion switch SC2.

[0100] The 2-1 switch S21 may include a first electrode to which the first voltage V1 is applied and a second electrode connected to the 2-1 node N21. The 2-2 switch S22 may include a first electrode connected to the 2-2 node N22 and a second electrode connected to ground. The 2-3 switch S23 may include a first electrode connected to the 2-1 node N21 and a second electrode connected to ground. The 2-4 switch S24 may include a first electrode connected to the 2-2 node N22 and a second electrode connected to the 2-3 node N23.

[0101] The 2-1 capacitor C21 may include a first electrode connected to the 2-1 node N21 and a second electrode connected to the 2-2 node N22. The 2-2 capacitor C22 may include a first electrode connected to the 2-3 node N23 and a second electrode connected to ground.

[0102] The first conversion switch SC1 may include a first electrode to which the power supply voltage VDD is applied and a second electrode connected to the 2-1 node N21. The second conversion switch SC2 may include a first electrode to which the power supply voltage VDD is applied and a second electrode connected to the 2-2 node N22.

[0103] The second charge pump CP2 may perform a 2-1 operation and a 2-2 operation in the first mode (positive-negative mode). That is, in the first mode, the second charge pump CP2 may perform the operation of a negative charge pump.

[0104] In the 2-1 operation, the 2-1 switch S21 and the 2-2 switch S22 may be turned on, and the 2-3 switch S23, the 2-4 switch S24, the first conversion switch SC1, and the second conversion switch SC2 may be turned off. In addition, in the 2-1 operation, the path switch SW1 may be turned off. In the 2-1 operation, the first voltage V1 may be charged to the 2-1 capacitor C21 through the turned-on 2-1 switch S21 and 2-2 switch S22.

[0105] In the 2-2 operation, the 2-3 switch S23 and the 2-4 switch S24 may be turned on, and the 2-1 switch S21, the 2-2 switch S22, the first conversion switch SC1, and the second conversion switch SC2 may be turned off. In addition, in the 2-2 operation, the path switch SW1 may be turned off. In the 2-2 operation, the second voltage V2 may be output at the output terminal through the turned-on 2-3 switch S23 and 2-4 switch S24.

[0106] When the 2-1 operation is performed, the first voltage V1 is charged to the 2-1 capacitor C21, and when the 2-2 operation is performed, the polarity of the first voltage V1 charged to the 2-1 capacitor C21 is reversed and output from the output terminal of the second charge pump CP2. Therefore, the second charge pump CP2 may output a voltage that is -1 times the first voltage V1 as the second voltage V2.

[0107] In the 2-2 operation, the path switch SW1 is turned off. Therefore, the second voltage V2, which is the output of the second charge pump CP2, may be applied to the second input terminal TR2 of the signal generation unit SG.

[0108] In the first mode (positive-negative mode), the first voltage V1, which is the output of the first charge pump CP1, may be applied to the first input terminal TR1 of the signal generation unit SG, and the second voltage V2, which is the output of the second charge pump CP2, may be applied to the second input terminal TR2 of the signal generation unit SG. Thus, the signal generation unit SG may generate the touch drive signal TXS that swings between the first voltage V1 having a positive voltage and the second voltage V2 having a negative voltage.

[0109] The second charge pump CP2 may perform the 2-3 operation and the 2-4 operation in the second mode (only positive mode). That is, in the second mode, the second charge pump CP2 may perform the operation of a positive charge pump.

[0110] In the 2-3 operation, the second conversion switch SC2 and the 2-3 switch S23 may be turned on, and the 2-1 switch S21, the 2-2 switch S22, the 2-4 switch S24, and the first conversion switch SC1 may be turned off. In addition, in the 2-3 operation, the path switch SW1 may be turned off. In the 2-3 operation, the power supply voltage VDD may be charged to the 2-1 capacitor C21 through the turned-on second conversion switch SC2 and 2-3 switch S23.

[0111] In the 2nd - 4th operations, the first conversion switch SC1 and the 2nd - 4th switch S24 can be turned on, and the 2nd - 1st switch S21, the 2nd - 2nd switch S22, the 2nd - 3rd switch S23, and the second conversion switch SC2 can be turned off. In addition, in the 2nd - 4th operation, the path switch SW1 can be turned on. In the 2nd - 4th operation, the second voltage V2 can be output at the output terminal through the turned - on first conversion switch SC1 and the 2nd - 4th switch S24.

[0112] When the 2nd - 3rd operation is performed, the power supply voltage VDD charges the 2nd - 1st capacitor C21, and when the 2nd - 4th operation is performed, the power supply voltage VDD applied to the first electrode of the first conversion switch SC1 and the power supply voltage VDD charged to the 2nd - 1st capacitor C21 are added together and output from the output terminal of the second charge pump CP2. Therefore, the second charge pump CP2 can output a voltage approximately twice the power supply voltage VDD as the second voltage V2.

[0113] In the 2nd - 4th operation, the path switch SW1 is turned on. Therefore, the second voltage V2, which is the output of the second charge pump CP2, can be applied to the first input terminal TR1 of the signal generation unit SG.

[0114] In the second mode (only positive mode), the first voltage V1, which is the output of the first charge pump CP1, and the second voltage V2, which is the output of the second charge pump CP2, can be commonly applied to the first input terminal TR1 of the signal generation unit SG, so that the signal generation unit SG can generate the touch drive signal TXS that swings between the first voltage V1 having a positive voltage and the ground voltage.

[0115] Figure 15 is a waveform diagram showing the input voltage VS1 and the touch drive signal TXS of the signal generation unit according to the comparative example in the heavy - load positive swing.

[0116] The touch drive unit according to the comparative example may include a positive charge pump and a negative charge pump. Here, the input voltage VS1 of the signal generation unit may be the voltage applied to the first input terminal of the signal generation unit.

[0117] Refer to Figure 15 , in the case where only the positive - voltage swing is required under the condition of a large load due to an increase in the size of the touch panel, there may be a problem that the regulation of the output voltage fails due to insufficient capacity of the positive charge pump.

[0118] The signal generation unit generates a sine signal based on the output voltage of the positive charge pump. Therefore, when the regulation of the output voltage fails, distortion may occur in the sine signal. The distortion of the sine signal may generate unwanted harmonic components, and the EMI may deteriorate due to the harmonic components.

[0119] Figure 16 is a waveform diagram showing the input voltage VS1 and the touch drive signal TXS of the signal generation unit SG according to the present embodiment in the positive swing of a heavy load.

[0120] Referring to Figures 1 to 14 and Figure 16 , the touch drive unit 400 may include a positive charge pump (i.e., the first charge pump CP1) and a charge pump capable of positive and negative conversion (i.e., the second charge pump CP2). Here, the input voltage VS1 of the signal generation unit SG may be the voltage applied to the first input terminal TR1 of the signal generation unit SG.

[0121] In the case where only the positive voltage swing is required under the condition of a large load due to an increase in the size of the touch panel, the second charge pump CP2, which is the charge pump capable of positive and negative conversion, may operate as a positive charge pump.

[0122] That is, in the case where only the positive voltage swing is required under the condition of a large load due to an increase in the size of the touch panel, the first charge pump CP1 and the second charge pump CP2 will operate as a dual charge pump that substantially outputs the same positive voltage.

[0123] In this way, when both the first charge pump CP1 and the second charge pump CP2 operate as positive charge pumps, the capacity of the positive charge pump (i.e., the first charge pump CP1, the second charge pump CP2) increases, and the problem of output voltage regulation failure can be prevented. Therefore, the EMI can be improved by preventing the distortion of the sine signal generated when the output voltage regulation fails.

[0124] In addition, since the current flowing through each charge pump is reduced, the loss of the charge pump can be prevented, and thus the efficiency of the positive charge pump (i.e., the first charge pump CP1, the second charge pump CP2) can be improved.

[0125] According to the present embodiment, in the case where a positive swing of a heavy load is required, the second charge pump CP2 can be converted from a negative charge pump to a positive charge pump to cope with the heavy load, whereby the reliability of the touch drive unit 400 can be improved.

[0126] In addition, since the second charge pump CP2 is converted from a negative charge pump to a positive charge pump, it is possible to prevent distortion from occurring in the sine wave due to insufficient capacity of the first charge pump CP1 and deterioration of EMI due to the distortion. Therefore, the EMI of the display device can be reduced.

[0127] In addition, since the second charge pump CP2 is converted from a negative charge pump to a positive charge pump, the current flowing into the first charge pump CP1 can be reduced, and accordingly, the power consumption of the touch driving unit 400 can be reduced.

[0128] Figure 17 is a cross-sectional view showing an example of a display device Figure 1 of.

[0129] Referring to Figures 1 to 14 , Figure 16 and Figure 17 , the display device may include the display panel 100, the display panel driving unit 200, the touch panel 300, the display circuit board PC, and the touch driving unit 400.

[0130] The display panel 100 may include a main area MA and a sub-area SBA. The main area MA may include a display area DA for displaying an image and a non-display area NDA that is a peripheral area of the display area DA.

[0131] The display area DA may include the pixels P for displaying an image. The sub-area SBA may protrude in one direction from one side of the main area MA.

[0132] For example, the sub-area SBA may be curved as Figure 17 shown, and in this case, the sub-area SBA may be disposed on the lower surface of the main area MA. The sub-area SBA may overlap the main area MA in the thickness direction of the substrate SUB when curved. The display panel driving unit 200 may be disposed in the sub-area SBA.

[0133] The display panel 100 may include a substrate SUB, a thin film transistor layer TFTL, a light emitting element layer EML, and a packaging layer TFEL. The touch panel 300 may be disposed on the front surface of the display panel 100.

[0134] The thin film transistor layer TFTL may be disposed on the substrate SUB. The thin film transistor layer TFTL may be disposed in the main area MA and the sub-area SBA. The thin film transistor layer TFTL may include thin film transistors.

[0135] The light-emitting element layer EML may be disposed on the thin-film transistor layer TFTL. The light-emitting element layer EML may be disposed in the display area DA of the main area MA. The light-emitting element layer EML may include light-emitting elements disposed in a light-emitting portion.

[0136] The encapsulation layer TFEL may be disposed on the light-emitting element layer EML. The encapsulation layer TFEL may be disposed in the display area DA and the non-display area NDA of the main area MA. The encapsulation layer TFEL may include at least one inorganic film and at least one organic film for encapsulating the light-emitting element layer EML.

[0137] The touch panel 300 may be formed on or mounted on the encapsulation layer TFEL. The touch panel 300 may be disposed in the display area DA of the main area MA. The touch panel 300 may sense the touch of a person or an object using touch electrodes.

[0138] A window WD may be disposed on the touch panel 300. The window WD may be attached to the touch panel 300 by a transparent bonding member such as an optically clear adhesive (OCA) film or an optically clear resin (OCR). The window WD may also be an inorganic substance such as glass, or an organic substance such as plastic or a polymer material. In order to prevent a reduction in the visibility of an image due to external light reflection, a polarizing film may be additionally disposed between the touch panel 300 and the window WD.

[0139] The display panel driving unit 200 may generate signals and voltages for driving the display panel 100. A part of the display panel driving unit 200 may be formed of an integrated circuit (IC) and attached to the display panel 100 by a chip on glass (COG) method, a chip on plastic (COP) method, or an ultrasonic bonding method, but the present invention is not limited thereto. For example, a part of the display panel driving unit 200 may be attached to the display circuit board PC by a chip on film (COF) method.

[0140] The display circuit board PC can be attached to one end of the sub-region SBA of the display panel 100. Thus, the display circuit board PC can be electrically connected to the display panel 100 and the display panel driving unit 200. The display circuit board PC can be a flexible printed circuit board, a printed circuit board, or a flexible film such as a chip on film.

[0141] The touch driving unit 400 can be disposed on the display circuit board PC. The touch driving unit 400 can be formed of an integrated circuit (IC) and attached to the display circuit board PC.

[0142] For example, the touch driving unit 400 can be electrically connected to the touch electrodes of the touch panel 300. The touch driving unit 400 can apply a touch driving signal TXS to the touch electrodes and measure the amount of charge change of the mutual capacitance of each of the plurality of touch nodes formed by the touch electrodes.

[0143] For example, the touch driving unit 400 can measure the change in capacitance of a plurality of touch nodes according to the voltage magnitude or current amount change of the touch sensing signal RXS received through the touch electrodes. In this way, the touch driving unit 400 can determine whether a user touches or approaches based on the amount of charge change of the mutual capacitance of each of the plurality of touch nodes. The touch of the user can refer to the direct contact of an object such as the user's finger or pen with one surface of the window WD disposed on the touch panel 300. The approach of the user can also refer to the hovering of an object such as the user's finger or pen on one surface of the window WD.

[0144] The touch driving unit 400 can correct the touch sensing signal RXS according to the noise application level based on low-temperature driving, charging mode, high-frequency application, electromagnetic noise application state, etc., so as to extract the touch coordinates, or can autonomously switch the driving mode.

[0145] For example, when judging the noise application state, the touch driving unit 400 can perform corrections such as rejecting the touch sensing signal RXS according to whether a body part or a detected object detected by the human body sensing sensor of the display panel 100 is detected. In addition, the touch driving unit 400 can selectively change the touch interested area to sense the touch of the user according to whether a body part located in the front surface direction of the display panel 100 is detected, and can also change the driving mode to a low power mode or a standby mode, etc.

[0146] Figure 18 It is a block diagram showing an electronic device 1000 according to an embodiment of the present invention. Figure 19 It is shown Figure 18 A diagram of an example in which the electronic device 1000 is implemented as a smart phone.

[0147] Referring to Figure 18 and Figure 19 , the electronic device 1000 may include a processor 1010, a memory device 1020, a storage device 1030, an input / output device 1040, a power supply 1050, and a display device 1060. At this time, the display device 1060 may be Figure 1 the display device. In addition, the electronic device 1000 may further include a plurality of ports that can communicate with a video card, a sound card, a memory card, a universal serial bus (USB) device, etc., or communicate with other systems.

[0148] According to an embodiment, as Figure 19 shown, the electronic device 1000 may be implemented as a smart phone. However, this is exemplary, and the electronic device 1000 is not limited thereto. For example, the electronic device 1000 may be implemented as a portable phone, a video phone, a smart tablet, a smart watch, a tablet PC, a vehicle navigator, a computer monitor, a notebook computer, a head-mounted display device, etc.

[0149] The processor 1010 may perform specific calculations or tasks. According to an embodiment, the processor 1010 may be a microprocessor, a central processing unit, an application processor, etc. The processor 1010 may be connected to other components through an address bus, a control bus, a data bus, etc. According to an embodiment, the processor 1010 may also be connected to an expansion bus such as a Peripheral Component Interconnect (PCI) bus.

[0150] The processor 1010 may output the input image data IMG and the input control signal CONT to Figure 2 the driving control unit 220 of

[0151] The memory device 1020 may store data required for the operation of the electronic device 1000. For example, the memory device 1020 may include non-volatile memory devices such as erasable programmable read-only memory (EPROM) devices, electrically erasable programmable read-only memory (EEPROM) devices, flash memory devices, phase change random access memory (PRAM) devices, resistance random access memory (RRAM) devices, nano floating gate memory (NFGM) devices, polymer random access memory (PoRAM) devices, magnetic random access memory (MRAM) devices, ferroelectric random access memory (FRAM) devices, etc., and / or volatile memory devices such as dynamic random access memory (DRAM) devices, static random access memory (SRAM) devices, mobile DRAM devices, etc.

[0152] The storage device 1030 may include a solid state drive (SSD), a hard disk drive (HDD), a compact disc read-only memory (CD-ROM), etc. The input / output device 1040 may include input devices such as a keyboard, a keypad, a touchpad, a touch screen, a mouse, etc., and output devices such as a speaker, a printer, etc. According to an embodiment, the display device 1060 may also be included in the input / output device 1040. The power supply 1050 may supply power required for the operation of the electronic device 1000. The display device 1060 may be connected to other components via the bus or other communication links.

[0153] Figure 20 is a diagram showing Figure 18 an example in which the electronic device 1000 is implemented as a vehicle display.

[0154] Refer toFigure 18 and Figure 20 , the electronic device 1000 can be implemented as an automotive display.

[0155] When the display device is used in a vehicle, safety problems may occur due to the influence of EMI on the vehicle's driving. When the display device is used for a vehicle, the vehicle's safety can be improved by reducing the EMI.

[0156] Industrial applicability According to the charge pump of the present invention described above, the touch driving unit including the charge pump, and the display device including the touch driving unit, it is possible to handle heavy loads, reduce power consumption, and reduce electromagnetic interference (EMI: Electro Magnetic Interference).

[0157] As described above, the present invention has been described with reference to the embodiments. However, those of ordinary skill in the art can understand that the present invention can be variously modified and changed without departing from the concept and scope of the present invention described in the claims.

Claims

1. A charge pump, comprising: A 2-1 switch including a first electrode to which a first voltage is applied and a second electrode connected to a 2-1 node; A 2-2 switch including a first electrode connected to a 2-2 node and a second electrode connected to ground; A 2-3 switch including a first electrode connected to the 2-1 node and a second electrode connected to the ground; A 2-4 switch including a first electrode connected to the 2-2 node and a second electrode connected to the 2-3 node; A 2-1 capacitor including a first electrode connected to the 2-1 node and a second electrode connected to the 2-2 node; A 2-2 capacitor including a first electrode connected to the 2-3 node and a second electrode connected to the ground; A first conversion switch including a first electrode to which a power supply voltage is applied and a second electrode connected to the 2-1 node; as well as The second conversion switch includes a first electrode to which the power supply voltage is applied and a second electrode connected to the 2-2 node.

2. The charge pump according to claim 1, wherein: In operation 2-1, The 2-1 switch and the 2-2 switch are turned on, The 2-3 switch, the 2-4 switch, the first conversion switch, and the second conversion switch are turned off.

3. The charge pump according to claim 2, wherein: In operation 2-2, The 2-3 switch and the 2-4 switch are turned on, The 2-1st switch, the 2-2nd switch, the first conversion switch, and the second conversion switch are turned off.

4. The charge pump according to claim 1, wherein: In the 2nd and 3rd operations, The second conversion switch and the 2-3 switch are turned on, The 2-1st switch, the 2-2nd switch, the 2-4th switch, and the first conversion switch are turned off.

5. The charge pump according to claim 4, wherein: In operations 2-4, The first conversion switch and the 2-4 switches are turned on, The 2-1st switch, the 2-2nd switch, the 2-3rd switch, and the second conversion switch are turned off.

6. A touch driving unit, comprising: A first charge pump receives a power supply voltage and outputs a first voltage; a second charge pump, receiving the power supply voltage and the first voltage and outputting a second voltage; a path switch, comprising a first electrode connected to the output end of the first charge pump and a second electrode connected to the output end of the second charge pump; as well as The signal generating unit includes a first input terminal connected to the output terminal of the first charge pump and a second input terminal connected to the output terminal of the second charge pump.

7. The touch driving unit according to claim 6, wherein: In the first mode, The path switch is disconnected, The first voltage is applied to the first input terminal of the signal generating unit, The second voltage is applied to the second input terminal of the signal generating section.

8. The touch driving unit according to claim 6, wherein: In the second mode, The path switch is turned on, The first voltage is applied to the first input terminal of the signal generating unit, The second voltage is applied to the first input terminal of the signal generating section.

9. The touch driving unit according to claim 6, wherein: The second charge pump comprises: A 2-1 switch including a first electrode to which the first voltage is applied and a second electrode connected to a 2-1 node; A 2-2 switch including a first electrode connected to a 2-2 node and a second electrode connected to ground; A 2-3 switch including a first electrode connected to the 2-1 node and a second electrode connected to the ground; A 2-4 switch including a first electrode connected to the 2-2 node and a second electrode connected to the 2-3 node; A 2-1 capacitor including a first electrode connected to the 2-1 node and a second electrode connected to the 2-2 node; A 2-2 capacitor including a first electrode connected to the 2-3 node and a second electrode connected to the ground; a first conversion switch including a first electrode to which the power supply voltage is applied and a second electrode connected to the 2-1 node; and The second conversion switch includes a first electrode to which the power supply voltage is applied and a second electrode connected to the 2-2 node.

10. The touch driving unit according to claim 9, wherein: In operation 2-1, The 2-1 switch and the 2-2 switch are turned on, The 2-3 switch, the 2-4 switch, the first conversion switch, and the second conversion switch are turned off. The path switch is opened.

11. The touch driving unit according to claim 10, wherein: In operation 2-2, The 2-3 switch and the 2-4 switch are turned on, The 2-1st switch, the 2-2nd switch, the first conversion switch, and the second conversion switch are turned off. The path switch is opened.

12. The touch driving unit according to claim 9, wherein: In the 2nd and 3rd operations, The second conversion switch and the 2-3 switch are turned on, The 2-1st switch, the 2-2nd switch, the 2-4th switch and the first conversion switch are turned off, The path switch is opened.

13. The touch driving unit according to claim 12, wherein: In operations 2-4, The first conversion switch and the 2-4 switches are turned on, The 2-1st switch, the 2-2nd switch, the 2-3rd switch and the second conversion switch are turned off, The path switch is turned on.

14. The touch driving unit according to claim 9, wherein: The first charge pump comprises: A 1-1 switch including a first electrode to which the power supply voltage is applied and a second electrode connected to a 1-2 node; A 1-2 switch including a first electrode connected to the 1-1 node and a second electrode connected to the ground; A 1-3 switch including a first electrode to which the power supply voltage is applied and a second electrode connected to the 1-1 node; A 1-4 switch including a first electrode connected to the 1-2 node and a second electrode connected to the 1-3 node; a 1-1th capacitor including a first electrode connected to the 1-1th node and a second electrode connected to the 1-2th node; and The 1-2 capacitor includes a first electrode connected to the 1-3 node and a second electrode connected to the ground.

15. The touch driving unit according to claim 14, wherein: In the 1-1 operation, The 1-1 switch and the 1-2 switch are turned on, The 1-3 switch and the 1-4 switch are turned off.

16. The touch driving unit according to claim 15, wherein: In operation 1-2, The 1-3 switch and the 1-4 switch are turned on, The 1-1 switch and the 1-2 switch are turned off.

17. The touch driving unit according to claim 6, wherein: Also includes: a multiplexer connected to the signal generating unit, Wherein, the multiplexer is connected to the sending electrodes of the touch panel.

18. A display device comprising: Display panel; A display panel driving unit, driving the display panel; A touch panel, arranged on the display panel; as well as A touch driving unit drives the touch panel, The touch drive unit is the touch drive unit according to any one of claims 6 to 17.

19. A touch driving unit, comprising: A first charge pump receives a power supply voltage and outputs a first voltage; a second charge pump, which outputs a second voltage in the first mode and a third voltage in the second mode; a path switch connected between an output terminal of the first charge pump and an output terminal of the second charge pump; as well as a signal generating unit including a first input terminal connected to the output terminal of the first charge pump and a second input terminal connected to the output terminal of the second charge pump, wherein, in the first mode, the second charge pump outputs the second voltage through the output terminal of the second charge pump based on the first voltage output from the first charge pump, and the path switch is turned off so that the second voltage is input to the second input terminal of the signal generating unit; In the second mode, the second charge pump outputs the third voltage through the output terminal of the second charge pump based on the power supply voltage, and the path switch is turned on so that the third voltage is input to the first input terminal of the signal generating unit.

20. The touch driving unit according to claim 19, wherein: The second voltage corresponds to the negative first voltage, and the third voltage corresponds to the first voltage.

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