KR20160072338A - Touch sensing system and display using the same - Google Patents

Abstract

The present invention relates to a touch sensing device and a display device using the same, capable of enhancing touch sensitivity. The touch sensing device includes an input node, an output node, a first switch device, a second switch device, an operational amplifier, a sampling capacitor, and a folding capacitor. The input node receives an input signal from a touch screen. The output node is connected with an input terminal of an analog-digital converter. The first switch device is connected between the input node and a first node and turned on / off by a first switch signal. The second switch device is connected between the first node and a second node and turned on / off by a second switch signal. The operational amplifier is connected with an input terminal connected with a third node, and the output node. The sampling capacitor is connected between the first node and the third node. The folding capacitor is connected between the second node and the third node.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a touch sensing device,

The present invention relates to a touch sensing device and a display device using the touch sensing device.

A user interface (UI) enables a user (a user) to communicate with various electric or electronic devices, thereby enabling a user to easily control the device as desired. Representative examples of the user interface include a keypad, a keyboard, a mouse, an on-screen display (OSD), a remote controller having infrared communication or radio frequency (RF) communication functions. User interface technology has been developed to enhance the user's sensibility and ease of operation. The user interface is evolving into touch UI, voice recognition UI, 3D UI and so on.

A capacitive touch screen can be implemented with capacitance sensors. The capacitive sensor can be divided into a capacitive type sensor or a mutual capacitive type sensor.

The mutual capacitance sensor includes a mutual capacitance (Cm) formed between the two electrodes Tx and Rx as shown in FIG. The sensing unit 12 applies a driving signal (or a stimulus signal) to the Tx lines Tx1 to Tx5 and senses a touch input based on the amount of charge change of the capacitors before and after touching the Rx lines Rx1 to Rx6. When the conductor approaches the mutual capacitance Cm, the mutual capacitance Cm is reduced. The sensing unit 12 includes a sample and hold amplifier (SHA) for sampling and amplifying a touch sensor signal, an analog-to-digital converter (ADC) for converting an output signal of the sample and hold amplifier (SHA) (Hereinafter referred to as "ADC"). The ADC outputs the touch raw data (Tdata) by converting the output signal of the sample and hold amplifier to digital data.

The magnetic capacitance sensor includes self capacitance (Cs) formed on each sensor electrode as shown in FIG. The sensing unit 14 supplies a charge to each of the sensor electrodes and senses a touch input based on the charge change amount of the capacitance Cs. When the conductor approaches the magnetic capacity, the magnetic capacity increases. The sensing unit 14 is divided into a sample-and-hold amplifying unit (SHA) for sampling and amplifying the touch sensor signal, and an ADC for converting the output signal of the sample-and-hold amplifying unit (SHA) into digital data. The ADC outputs the data (Tdata) by touching by converting the output signal of the sample and hold amplifier (SHA) into digital data.

The touch sensing apparatus further includes a digital processing unit for analyzing the data (Tdata) by touching from the sensing units (12, 14) to determine whether or not touch input is performed, and to calculate coordinate information of each touch input. In order to increase the touch sensitivity of the touch sensing device, it is necessary to accurately detect the amount of charge change of the touch sensor. To achieve this, the input range of the ADC must be wide, but it is difficult to improve the performance of the touch sensing device because the input range of the ADC is not wide enough. If the output signal of the sample and hold amplifier (SHA) exceeds the input range of the ADC, the excess data will saturate to the same value and the signal exceeding the input range of the ADC can not be expressed. When the supply voltage of the ADC is low, the input range of the ADC is limited to a narrow range. If the reference value of the FADC (Flash ADC) is increased and the input range is forcibly increased, the linearity of the FADC deteriorates because it deviates from the operating range of the amplifier.

The present invention provides a touch sensing device capable of increasing touch sensitivity.

The touch sensing apparatus of the present invention includes an input node for receiving an input signal from a touch screen, an output node connected to an input terminal of the analog-to-digital converter, an on / off switch connected between the input node and the first node, A second switch element connected between the first node and the second node and being turned on / off by the second switch signal, an input terminal connected to the third node, and a second switch element connected to the output node, An amplifier, a sampling capacitor coupled between the first node and the third node, and a folding capacitor coupled between the second node and the third node.

The touch sensing apparatus further includes a third switch element connected between the second node and the third node to turn on / off the third switch signal, and a third switch element connected between the first node and the output node, And a fifth switch element connected between the third node and the output node to turn on / off the fifth switch signal.

The display device of the present invention includes a display panel having a touch screen, a display driving circuit for writing pixel data of the input image to pixels of the display panel, and the touch sensing device.

The present invention adjusts the voltage range of the signal to be input to the ADC to be within the input range of the ADC using the folding capacitor. As a result, the present invention can increase the input range of the ADC, which can be represented by a digital value output from the ADC, thereby improving the touch sensitivity.

FIG. 1 is a diagram showing a mutual capacity type touch screen.
FIG. 2 is a view showing a magnetosensitive type touch screen.
3 is a view illustrating a display device according to an embodiment of the present invention.
4 is a view showing a sensing unit of the touch sensor driving unit shown in FIG.
FIG. 5 is a circuit diagram showing a first embodiment of the sample-and-hold amplifier shown in FIG.
6 is a waveform diagram showing on / off timings of the switch elements shown in FIGS. 5 and 9. FIG.
FIG. 7 is a diagram showing a saturated period in a signal input to the ADC beyond the input range of the ADC in the prior art.
8 is a diagram illustrating an example in which all voltages of an input signal of an ADC are expressed as a digital value by converting a voltage of a signal exceeding an input range of the ADC into an input range of the ADC by applying the present invention.
FIG. 9 is a circuit diagram showing a second embodiment of the sample and hold amplifier shown in FIG. 4. FIG.
10 is a waveform diagram of a switch signal showing a method of utilizing a folding capacitor of the sample and hold amplifier shown in FIG. 5 and FIG. 9 as a sampling capacitor.

The display device of the present invention can be applied to a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), an organic light emitting display , An OLED display, and an electrophoresis (EPD) display device. In the following embodiments, a liquid crystal display device is described as an example of a flat panel display device, but it should be noted that the display device of the present invention is not limited to a liquid crystal display device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Like reference numerals throughout the specification denote substantially identical components. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

3 and 4, the display apparatus of the present invention includes a display panel 100 and a touch screen (TSP). The touch screen (TSP) includes capacitive touch sensors.

The touch sensors sense the touch input using mutual capacitance or capacitance. The substrate on which the touch sensors are formed can be bonded on the display panel 100. [ Alternatively, the touch sensors may be formed on the lower substrate of the display panel 100 together with the pixel array, and may be embedded in the display panel 100 as an in-cell type.

The display device of the present invention includes a display driving circuit 102, 104, and 106 for writing pixel data of an input image into pixels, and a touch sensor driver 110 for sensing a touch input.

The pixel array of the display panel 100 includes pixels defined by data lines (S1 to Sm, m is a positive integer) and gate lines (G1 to Gn, where n is a positive integer). Each of the pixels includes a TFT (Thin Film Transistor) formed at the intersections of the data lines S1 to Sm and the gate lines G1 to Gn, a pixel electrode for receiving the data voltage through the TFT, And a storage capacitor (Cst) connected to the divided common electrode and the pixel electrode to maintain the voltage of the liquid crystal cell.

A black matrix, a color filter, and the like may be formed on the upper substrate of the display panel 100. The lower substrate of the display panel 100 may be implemented as a COT (Color Filter On TFT) structure. In this case, the color filter may be formed on the lower substrate of the display panel 100. [ On the upper substrate and the lower substrate of the display panel 100, a polarizing plate is attached and an alignment film for forming a pre-tilt angle of the liquid crystal is formed on the inner surface in contact with the liquid crystal. A column spacer for maintaining a cell gap of the liquid crystal layer is formed between the upper substrate and the lower substrate of the display panel 100.

A backlight unit may be disposed under the rear surface of the display panel 100. The backlight unit is implemented as an edge type or direct type backlight unit to irradiate the display panel 100 with light. The display panel 100 may be realized in any known liquid crystal mode such as TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, IPS (In Plane Switching) mode and FFS (Fringe Field Switching) mode. In a self-luminous display device such as an organic light emitting diode display device, a backlight unit is not required.

When the touch sensors are embedded in the pixel array, the touch sensors can be formed with the division patterns of the common electrode. When the touch sensors are embedded in the pixel array, the pixel array and the touch sensors are time-divisionally driven by the display period and the touch sensor driving period. The touch sensor supplies the common voltage Vcom to the pixels during the display period and senses the touch input during the touch sensor period driving period.

The display driver circuits 102, 104, and 106 include a data driver 102, a gate driver 104, and a timing controller 106.

The data driver 102 converts the digital video data RGB of the input image received from the timing controller 106 into an analog positive / negative gamma compensation voltage to output a data voltage. The data voltage output from the data driver 102 is supplied to the data lines S1 to Sm.

The gate driver 104 sequentially supplies a gate pulse (or a scan pulse) synchronized with the data voltage to the gate lines G1 to Gn to select a line of the display panel 100 into which the data voltage is written.

The timing controller 106 inputs timing signals such as a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal DE and a main clock MCLK input from the host system 108 And synchronizes the operation timings of the data driver 102, the gate driver 104, and the touch sensor driver 110. In FIG. 6, SDC is a data timing signal for controlling the operation timing of the data driver 102. GDC is a gate timing signal for controlling the operation timing of the gate driver 104. [

The host system 108 may be implemented in any one of a television system, a set top box, a navigation system, a DVD player, a Blu-ray player, a personal computer (PC), a home theater system, and a phone system. The host system 108 converts the digital video data of the input image into a format suitable for the resolution of the display panel 100, including a system on chip (SoC) with a built-in scaler. The host system 108 transmits the timing signals Vsync, Hsync, DE, and MCLK to the timing controller 106 together with the digital video data RGB of the input image. The host system 108 also executes an application program associated with coordinate information XY of the touch input input from the touch sensor driver 110. [

The touch sensor driver 110 converts the signals from the output channels of the touch screen TSP into digital data and generates data (Tdata) by touch. The touch sensor driver 110 executes a touch recognition algorithm using a digital arithmetic logic circuit. The touch recognition algorithm judges the touch input by comparing the data (Tdata) with a preset threshold value by touch, adds the identification code and the coordinate information (XY) to each touch input, and transmits it to the host system 108.

The sensing unit of the touch sensor driving unit 110 includes a sample and hold amplifier (SHA) 112 and an ADC 114. The differential amplifier 10 may be connected between the output channels of the touch screen TSP and the sample and hold amplifier 112.

The differential amplifier 10 amplifies the difference between the i-th (i is a positive integer) sensor signal input to the inverting input terminal (-) and the (i + 1) -th sensor signal input to the non-inverting input terminal And outputs the sensor signals S1 to S4. The differential amplifier 10 amplifies the difference between the signals received through the neighboring output channels in the touch screen TSP, thereby improving the signal-to-noise ratio (SNR) by making the signal component larger than noise. have. The differential amplifier 10 may be implemented with a pulley differential amplifier (Fully differential amplifier), but is not limited thereto. The pulley differential amplifier amplifies the difference signal and outputs a positive signal (P) and a negative signal (N).

The sample-and-hold amplifying unit 112 samples and amplifies an input signal (touch sensor signal) from the differential amplifier 10. The sample-and-hold amplifier 112 converts the voltage of the input signal to within the input range of the ADC 114 using a folding capacitor. The present invention can convert the input signal voltage of the sample and hold amplifier 112 using the folding capacitor to represent the voltage of the touch sensor signal which is not expressed in the prior art in the touch data Tdata output from the ADC. Further, the present invention can increase the expression range of the touch sensor by a desired amount using a folding capacitor.

5 is a circuit diagram showing a first embodiment of the sample & 6 is a waveform diagram showing on / off timing of the switch elements S1a to S5a and S1b to S5b. 5, the sample-and-hold amplifier 112 receives the positive polarity signal P and the negative polarity signal N and outputs the positive polarity signal P and the negative polarity signal N, but is not limited thereto. For example, the sample and hold amplifier 112 may include one input node and one output node as shown in FIG.

5 and 6, the sample and hold amplifier 112 includes a first input node nin1 and a negative polarity input signal Vin (N) for receiving a positive polarity input signal Vin (P) A positive output node nout1 for outputting a positive output signal Vout (P) and a negative output node nout2 for outputting a negative output signal Vout (N) nout2. The output nodes nout1 and nout2 are connected to the input terminals of the ADC 114. [

The sample-and-hold amplifier 112 includes a plurality of switch elements S1a to S5a and S1b to S5b, sampling capacitors Cs1 and Cs2, folding capacitors Cf1 and Cf2, and an operational amplifier OP-AMP do. The switch elements S1a to S5a and S1b to S5b are turned on / off as shown in FIG. 6 under the control of the digital arithmetic logic circuit or the timing controller 106 of the touch sensor driver 110.

6, the high logic level of the switch control signals S1 to S5 controls the on-timing of the switch elements S1a to S5a, S1b to S5b, and the low logic level, Off timing of the switch elements S1a to S5a, S1b to S5b.

The 1a-th switch element S1a is connected between the first input node nin1 and the 1a-th node n1a. The 1a-th switch element S1a switches the current path between the first input node nin1 and the 1a-th node n1a in response to the first switch signal S1. The first 1b switch element S1b is connected between the second input node nin2 and the first node n1b. The first switching element S1b switches the current path between the second input node nin2 and the first node n1b in response to the first switch signal S1.

The 2a switch element S2a is connected between the 1a-th node n1a and the 2a-th node n2a. The 2a switching element S2a switches the current path between the 1a-th node n1a and the 2a-th node n2a in response to the second switch signal S2. The second switching element S2b is connected between the first node n1b and the second node n2b. The second switching element S2b switches the current path between the first node n1b and the second node n2b in response to the second switch signal S2.

The 3a switching element S3a is connected between the 2a node n2a and the 3a node n3a. The 3a switching element S3a switches the current path between the 2a-th node n2a and the 3a-th node n3a in response to the third switch signal S3. And the third switching element S3b is connected between the second node n2b and the third node n3b. The 3a switching element S3b switches the current path between the 2b node n2b and the 3b node n3b in response to the third switch signal S3.

The fourth switch element S4a is connected between the first node n1a and the positive output node nout1. The fourth switching element S4a switches the current path between the first node n1a and the positive output node nout1 in response to the fourth switch signal S4. The fourth switching element S4b is connected between the first node n1a and the negative output node nout2. The fourth switching element S4b switches the current path between the first node n1b and the negative output node nout2 in response to the fourth switch signal S4.

The 5a-th switch element S5a is connected between the 3a-th node n3a and the positive output node nout1. The 5a-th switch element S5a switches the current path between the 3a-th node n3a and the positive output node nout1 in response to the fifth switch signal S5. The fifth switch element S5b is connected between the third node n3b and the negative output node nout2. The fifth switch element S5b switches the current path between the third node n3b and the negative output node nout2 in response to the fifth switch signal S5.

The operational amplifier OP-AMP includes a first input terminal connected to the third node n3a, a second input terminal connected to the third node n3b, a first output terminal connected to the positive output node nout1, And a second output terminal connected to the negative output node nout2.

The first sampling capacitor Cs1 is connected between the 1a-th node n1a and the 3a-th node n3a. The second sampling capacitor Cs2 is connected between the first node n1b and the third node n3b.

The first folding capacitor Cf1 is connected between the 2a node n2a and the 3a node n3a. The second folding capacitor Cf2 is connected between the second node n2b and the third node n3b.

Hereinafter, the operation of the sample-and-hold amplifier 112 will be described with reference to FIGS. 5 and 6. FIG.

During the first period t1 the fifth and fifth switch elements S5a and S5b are turned on in response to the fifth switch S5 and the first and second switch elements S1a and S1b are turned on Off state. As a result, the operational amplifier OP-AMP is reset during the first period t1. During the first period t1, the other switch elements S2a, S2b, S3a, S3b, S4a, and S4b may maintain the off state as shown in FIG. 6, but the switch elements S2a, S2b, S3a, And S4b do not affect the reset operation of the operational amplifier OP-AMP.

During the second period t2, the 1a and 1b switch elements S1a and S1b are turned on in response to the first switch signal S1. During the second period t2, the sampling capacitors Cs1 and Cs2 charge the input signal Vin (P, N) supplied through the first and the first switching elements S1a and S1b. The fourth switch elements S4a and S4b must be off before the first and the first switch elements S1a and S1b are turned on. During the second period t2, the fourth and fourth switch elements S4a and S4b maintain the off state and the third switch elements S3a and S3b maintain the on state. The 3a and 3b switch elements S3a and S3b and the 1a and 1b switch elements S1a and S1b need not be synchronized. The 3a and 3b switch elements S3a and S3b may be turned off after being turned on once during the on period t2 of the 1a and 1b switch elements S1a and S1b. During the second period t2, the third switch elements S3a and S3b are turned off and floated while the charges of the folding capacitors Cf1 and Cf2 are all discharged. The third switch elements S3a and S3b are turned off and remain in the floating state before the first and first switching elements S1a and S1b are turned on during the second period t1.

During the third period t3, the first and first switching elements S1a and S1b are turned off. At this time, the input signal Vin (P, N) is sampled to the sampling capacitors Cs1 and Cs2. During the third period t3, the 2a, 2b, 4a and 4b switch elements S2a, S2b, S4a and S4b must remain off. During the third period t3, the third, third, fifth, and fifth switch elements S3a, S3b, S5a, and S5b may be in the off state as shown in FIG. 6, but are not limited thereto.

During the fourth period t4, the 2a and 2b switch elements S2a and S2b are turned on in response to the second switch signal S2. At this time, the charges of the sampling capacitors Cs1 and Cs2 are shared with the folding capacitors Cf1 and Cf2. During the third period t3, the remaining switches S1a, S1b, S3a, S3b, S4a, S4b, S5a, and S5b remain off.

During the fifth period t5, the 2a, 2b, 4a and 4b switch elements S4a and S4b are turned on in response to the second and fourth switch signals S2 and S4. At this time, the voltage sampled by the folding capacitors Cf1 and Cf2 and the sampling capacitors Cs1 and Cs2 is held and the voltage is converted by the ADC 114 into a digital value, do. During the fifth period t5, the remaining switches S1a, S1b, S3a, S3b, S5a, and S5b remain off.

The voltage range of the input signal Vin is reduced by the folding capacitors Cf1 and Cf2 and adjusted within the input range of the ADC 114 as shown in Equation 1 . As a result, the present invention can increase the input range of the ADC that can be represented by the data (Tdata) with the touch output from the ADC 114, thereby improving the touch sensitivity. When the power supply voltage of the ADC 114 is low, the input range of the ADC 114 may be limited. However, according to the present invention, an input range that can be represented by a digital value can be widely applied regardless of the power supply voltage of the ADC 114 . When the input range of the ADC 114 is limited due to the characteristics of the semiconductor device, the present invention can widen the input range of the ADC 114, which can be expressed as a digital value regardless of the characteristics of the semiconductor device. In addition, since the present invention operates within the normal operating characteristic range of an operational amplifier (OP-AMP), linearity can be satisfied.

Where Cs is the sampling capacitor and Cf is the capacitance of the poling capacitor.

7 is a diagram showing a saturation interval in a signal input to the ADC 112 beyond the input range of the ADC 112 in the prior art. In the case of the prior art, voltages exceeding the input range of the ADC 114 can not be represented as digital values because they are converted to the same digital value in the ADC. 8 is a diagram illustrating an example in which all voltages of an input signal of an ADC are expressed as digital values by converting a voltage of a signal exceeding an input range of the ADC into an input range of the ADC by applying the present invention. 8A illustrates an input signal Vin and an output signal Vout of the sample-and-hold amplifying unit 112. As shown in FIG. 8 (b) shows the touch-tone data Tdata obtained by converting the output signal Vout of the sample-and-hold amplifier 112 to a digital value by the ADC 112 as shown in (a).

9 is a circuit diagram showing a second embodiment of the sample & The switch elements S11 to S55 of the sample and hold amplifier 112 are controlled as shown in FIG.

9, the sample-and-hold amplifier 112 includes a plurality of switch elements S1 to S5, a sampling capacitor Cs, a folding capacitor Cf, and an operational amplifier OP-AMP.

The first switch element S11 is connected between the input node nin and the first node n1. The first switch element S11 switches the current path between the input node nin and the first node n1 in response to the first switch signal S1.

The second switch element S22 is connected between the first node n1 and the second node n2. The second switch element S22 switches the current path between the first node n1 and the second node n2 in response to the second switch signal S2.

The third switch element S33 is connected between the second node n2 and the third node n3. The third switch element S33 switches the current path between the second node n2 and the third node n3 in response to the third switch signal S3.

The fourth switch element S44 is connected between the first node n1 and the output node nout. The fourth switch element S44 switches the current path between the first node n1 and the output node nout in response to the fourth switch signal S4.

The fifth switch element S55 is connected between the third node n3 and the output node nout. The fifth switch element S55 switches the current path between the third node n3 and the output node nout in response to the fifth switch signal S5.

The operational amplifier OP-AMP includes a first input terminal connected to the third node n3, a second input terminal supplied with the reference voltage, and an output terminal connected to the output node nout.

The operation of the sample-and-hold amplifying unit 112 shown in FIG. 9 is substantially the same as that of the sample-and-hold amplifying unit 112 described above with reference to FIGS. 5 and 6, and a detailed description thereof will be omitted.

When the folding capacitors Cf1 and Cf2 are not needed, the folding capacitors Cf1 and Cf2 can be utilized as sampling capacitors. When the sample-and-hold amplifier 112 shown in FIGS. 5 and 9 is controlled as shown in FIG. 10 without changing the circuit configuration, the folding capacitors Cf1 and Cf2 operate as sampling capacitors.

10 is a waveform diagram of a switch signal showing a method of utilizing a folding capacitor of the sample and hold amplifier shown in FIG. 5 and FIG. 9 as a sampling capacitor.

5 and 10, the second switch signal S2 is maintained at the high logic level, so that the second and third switch elements S2a and S2b are turned off during the first to fourth periods t11 to t44 State. The third switch signal S3 is held at a low logic level to maintain the third and third switch elements S3a and S3b in the off state during the first to fourth periods t11 to t44.

During the first period t11, the fifth and fifth switch elements S5a and S5b are turned on in response to the fifth switch S5 and the first and the first switch elements S1a and S1b remain off . As a result, the operational amplifier OP-AMP is reset during the first period t11. During the first period t11, the other switch elements S2a, S2b, S3a, S3b, S4a, S4b are not in any state.

During the second period t2, the 1a and 1b switch elements S1a and S1b are turned on in response to the first switch signal S1. During the second period t2, the sampling capacitors Cs1, Cs2, Cf1 and Cf2 charge the input signal Vin (P, N) supplied through the first and the first switching elements S1a and S1b. The fourth switch elements S4a and S4b must be off before the first and the first switch elements S1a and S1b are turned on. During the second period t2, the 2a, 2b, 3a, and 3b switch elements S2a, S2b, S3a, and S3b are in any state. During the second period t2, the fifth switch elements S5a and S5b can maintain the ON state.

During the third period t3, the first and first switching elements S1a and S1b are turned off. At this time, the input signal Vin (P, N) is sampled to the sampling capacitors Cs1, Cs2, Cf1 and Cf2. During the third period t3, the 2a, 2b, 4a and 4b switch elements S2a, S2b, S4a and S4b are turned off when the 1a and 1b switch elements S1a and S1b are turned off Off state. During the third period t3, the third, third, fifth, and fifth switch elements S3a, S3b, S5a, and S5b may be in an off state, but are not limited thereto.

During the fourth period t4, the 2a, 2b, 4a and 4b switch elements S2a, S2b, S4a and S4b are turned on in response to the second and fourth switch signals S2 and S4 . At this time, the sampled voltage is held in the sampling capacitors Cs1, Cs2, Cf1, and Cf2, and the voltage is converted by the ADC 114 into a digital value, that is, a touch data Tdata. During the fourth period t4, the remaining switches S1a, S1b, S3a, S3b, S5a, and S5b remain off.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

100: display panel 102: data driver
104: Gate driver 106: Timing controller
108: host system 110: touch sensor driver
112: Tx driver 114: ADC
S11 to S55, S1a to S5a, S1b to S5b:
Cs, Cs1, Cs2: sampling capacitor
Cf, Cf1, Cf2: folding capacitor

Claims (6)

An input node for receiving an input signal from a touch screen;
An output node coupled to an input terminal of the analog-to-digital converter;
A first switch element connected between the input node and the first node and being turned on / off by a first switch signal;
A second switch element connected between the first node and the second node and being turned on / off by a second switch signal;
An input terminal connected to the third node and an operational amplifier connected to the output node;
A sampling capacitor coupled between the first node and the third node; And
And a folding capacitor coupled between the second node and the third node. The method according to claim 1,
A third switch element connected between the second node and the third node to turn on / off the third switch signal;
A fourth switch element connected between the first node and the output node and being turned on / off by a fourth switch signal; And
And a fifth switch element connected between the third node and the output node to turn on / off the fifth switch signal. 3. The method of claim 2,
During the first period, the fifth switch element is turned on in response to the fifth switch, the first switch element remains off,
During the second period, the first switch element is turned on in response to the first switch signal,
During the third period, the first switch element is turned off,
During the fourth period, the second switch element is turned on in response to the second switch signal,
And during the fifth period, the second and fourth switch elements are turned on in response to the second and fourth switch signals. The method of claim 3,
During the first period, the fifth switch element is turned on in response to the fifth switch and the first switch element remains off,
During the second period, the first switch element is turned on in response to the first switch signal,
During the third period, the first switch element is turned off,
And during the fourth period, the second and fourth switch elements are turned on in response to the second and fourth switch signals. A display panel having a touch screen;
A display driving circuit for writing pixel data of an input image to pixels of the display panel; And
And a touch sensor driver for converting input signals from output channels of the touch screen into digital data and generating data by touching,
The touch sensor driver includes:
An input node through which the input signal is received;
An output node coupled to an input terminal of the analog-to-digital converter;
A first switch element connected between the input node and the first node and being turned on / off by a first switch signal;
A second switch element connected between the first node and the second node and being turned on / off by a second switch signal;
An input terminal connected to the third node and an operational amplifier connected to the output node;
A sampling capacitor coupled between the first node and the third node; And
And a folding capacitor connected between the second node and the third node. 6. The method of claim 5,
The touch sensor driver includes:
A third switch element connected between the second node and the third node to turn on / off the third switch signal;
A fourth switch element connected between the first node and the output node and being turned on / off by a fourth switch signal; And
And a fifth switch element connected between the third node and the output node to turn on / off the fifth switch signal.

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