KR102016069B1 - Touch sensing apparatus and method - Google Patents

Abstract

The present invention relates to a touch sensing device and a method capable of reducing noise by accurately adjusting the slew rate of a driving pulse according to noise and accurately sensing a touch signal. When a signal is filtered through a plurality of band pass filters having different frequency bands and noise is detected by at least one band pass filter, a slew rate different from a driving pulse used for driving a touch sensor among a plurality of driving pulses having different slew rates is obtained. Selecting a drive pulse having a, and sequentially supply the selected drive pulse to the plurality of scan lines of the touch sensor to drive the touch sensor.

Description

TOUCH SENSING APPARATUS AND METHOD}

The present invention relates to a touch sensing device, and more particularly to a touch sensing device and method that can reduce the noise and accurately sense the touch signal by adjusting the slew rate of the driving pulse according to the noise.

Today, touch sensors capable of inputting information by touch on screens of various display devices are widely applied as information input devices of computer systems. Since the touch sensor moves or selects display information by simply touching the screen with a finger or a stylus, it can be easily used by anyone of all ages.

The touch sensing device outputs touch information by sensing a touch and a touch position generated by a touch sensor on the display device, and the computer system analyzes the touch information and performs a command. As the display device, a flat panel display device such as a liquid crystal display device, a plasma display panel, an organic light emitting diode display device, or the like is mainly used. Touch sensor technology includes a resistive film method, a capacitive method, an optical method, an infrared method, an ultrasonic method, and an electromagnetic method according to a sensing principle.

The touch sensor is composed of an on-cell touch sensor manufactured in the form of a panel and attached to an upper portion of the display device, or an in-cell touch sensor embedded in a pixel matrix of the display device. It consists of As the touch sensor, a photo touch sensor that recognizes a touch according to a change in light intensity using a photo transistor, and a capacitive touch sensor that recognizes a touch according to a capacitive variable are mainly used.

In general, the touch controller drives a touch sensor by applying a driving pulse to a sensing electrode of the touch sensor, senses a touch position by using a readout signal of a touch sensor indicating a change in capacitance depending on the presence or absence of a touch, and adjusts touch point coordinates. Calculate and send to host computer.

However, the conventional touch controller has a problem in that the touch signal cannot be accurately sensed due to a low signal-to-noise ratio (SNR) due to a noise component introduced into the readout signal through the touch sensor from the outside.

The present invention has been made to solve the above-described problems of the prior art, the problem to be solved by the present invention is a touch sensing device that can reduce the noise and accurately sense the touch signal by adjusting the slew rate of the driving pulse according to the noise And to a method.

In order to solve the above problems, the touch sensing device according to an embodiment includes a touch sensor; And a touch controller that drives the touch sensor and adjusts the slew rate of a driving pulse for driving the touch sensor according to whether the noise is measured by measuring noise through a readout signal from the touch sensor.
According to an exemplary embodiment, a touch sensing method includes driving a touch sensor using a driving pulse, filtering a readout signal from the driven touch sensor to measure noise, and measuring the noise according to a measurement result of the noise. And a second step of adjusting the slew rate.
The touch controller (second step) filters the readout signal from the touch sensor through a plurality of band pass filters having different frequency bands, and when noise is detected by at least one band pass filter, a plurality of driving pulses having different slew rates. The driving pulse having a slew rate different from the driving pulse used for driving the touch sensor is selected, and the selected driving pulse is sequentially supplied to the plurality of scan lines of the touch sensor to drive the touch sensor.
The touch controller includes a driving pulse generator for generating and outputting a square wave driving pulse; A slew rate adjusting unit generating the plurality of driving pulses by using the square wave driving pulses supplied from the driving pulse generating unit, and selecting and outputting any one of the driving pulses corresponding to the input selection signal; A touch sensor driver for sequentially driving a plurality of scan lines of the touch sensor unit by using a driving pulse supplied from the slew rate adjusting unit; A noise measuring unit including a plurality of band pass filters and generating a selection signal according to the output of the plurality of band pass filters and outputting the selected signal to a slew rate adjusting unit; A readout circuit for outputting touch sensing data indicating whether the touch is sensed using the readout signal from the touch sensor; And a signal processor configured to calculate and output touch coordinates using touch sensing data from the readout circuit.

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The noise measuring unit outputs a selection signal for selecting a small driving pulse having a slew rate different from the driving pulse used to drive the touch sensor unit when detecting the noise, and outputs a driving pulse used to drive the touch sensor if the noise is not detected. Outputs a selection signal for holding.

The slew rate adjusting unit includes: a plurality of inverters for outputting a plurality of driving pulses having different slew rates by adjusting the square wave driving pulses from the driving pulse generator to have different slew rates through different driving intensities; A multiplexer for selecting and outputting one of the driving pulses output from the plurality of inverters in response to the selection signal is provided.

The touch controller (in the touch sensing method) measures noise from the readout signal of the touch sensor unit and, when noise is detected, performs the slew rate adjustment operation of the driving pulse until the noise does not occur within a threshold value in the readout signal. Repeat steps 1 and 2. The touch controller may perform the slew rate adjustment operation of the driving pulse while driving the touch sensor, when the power is turned on, during a period in which no touch occurs in the touch sensor, or according to a user's instruction.

The second step of the touch sensing method may include generating and outputting a square wave driving pulse; Outputting a plurality of driving pulses having different slew rates through the plurality of inverters having different driving intensities from the square wave driving pulses; Generating and outputting a selection signal for selecting any one of a plurality of driving pulses having different slew rates according to the noise detection result; And selecting one of a plurality of driving pulses having different slew rates in response to the selection signal. The generating and outputting of the selection signal and selecting and outputting one of the plurality of driving pulses include selecting and outputting a driving pulse having a slew rate different from the driving pulse used to drive the touch sensor when the noise detection signal is output. If no noise is detected, the driving pulse used to drive the touch sensor is maintained.

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The touch sensing device and method according to the present invention can accurately sense the touch signal by measuring the noise detected from the readout signal and adjusting the slew rate of the driving pulse according to the measured noise to reduce harmonic noise and increase the SNR.

1 is a circuit block diagram schematically illustrating a configuration of a display device having a touch sensing device according to an exemplary embodiment of the present invention.
FIG. 2 is a diagram illustrating a structure of the capacitive touch sensor illustrated in FIG. 1.
3 is a circuit block diagram illustrating a configuration of the touch controller shown in FIG. 1.
FIG. 4 is a circuit block diagram showing the configuration of the slew rate adjusting unit shown in FIG. 3.
FIG. 5 is a flowchart for describing a slew rate adjusting method according to whether or not noise is detected in the noise measuring unit illustrated in FIG. 3 step by step.
6A to 6C are simulation waveform diagrams showing noise reduction results according to slew rate adjustment of a driving pulse in the touch sensing device according to an exemplary embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a block diagram illustrating a configuration of a display device including a touch sensing device according to an exemplary embodiment of the present invention, and FIG. 2 is a diagram illustrating a structure of the capacitive touch sensor 20 illustrated in FIG. 1. .

The display device having the touch sensing device shown in FIG. 1 includes a display panel 10, a panel driver 16 including a data driver 12 and a gate driver 14 for driving the display panel 10, and a panel driver. A timing controller 18 for controlling 16 is provided, a touch sensor 20 on the display panel 10, and a touch controller 30 for driving the touch sensor 20. The timing controller 18 and the touch controller 30 are connected to the host computer 50.

The timing controller 18 and the data driver 12 may be integrated into respective integrated circuits (ICs), or the timing controller 18 may be integrated into the data driver 12 and integrated into one IC. The touch controller 30 and the timing controller 18 may also be integrated into respective ICs, or the touch controller 30 may be integrated into the timing controller 18 and integrated into one IC.

The display panel 10 includes a pixel matrix in which a plurality of pixels are arranged. The pixel matrix displays a graphical user interface (GUI) and other images that include pointers or cursors. As the display panel 10, a flat panel display panel such as a liquid crystal display panel (hereinafter, referred to as a liquid crystal panel), a plasma display panel, and an organic light emitting diode display panel may be mainly used. Hereinafter, a liquid crystal panel will be described as an example.

When a liquid crystal panel is used as the display panel 10, the display panel 10 includes a color filter substrate on which a color filter array is formed, a thin film transistor substrate on which a thin film transistor array is formed, and a liquid crystal layer between the color filter substrate and the thin film transistor substrate. And a polarizing plate attached to the outer surface of the color filter substrate and the thin film transistor substrate, respectively. The display panel 10 displays an image through a pixel matrix in which a plurality of pixels are arranged. Each pixel realizes a desired color by using a combination of red, green, and blue sub-pixels that adjust light transmittance by varying the liquid crystal array according to the data signal. Each subpixel includes a thin film transistor TFT connected to a gate line GL and a data line DL, a liquid crystal capacitor Clc connected in parallel with the thin film transistor TFT, and a storage capacitor Cst. The liquid crystal capacitor Clc charges the data signal supplied to the pixel electrode through the thin film transistor TFT and the difference voltage between the common voltage Vcom supplied to the common electrode and drives the liquid crystal according to the charged voltage to thereby transmit light. Adjust The storage capacitor Cst keeps the voltage charged in the liquid crystal capacitor Clc stable. The liquid crystal layer is driven by a vertical electric field such as twisted nematic (TN) mode or vertical alignment (VA) mode, or by a horizontal electric field such as IPS (In-Plane Switching) mode or FFS (Fringe Field Switching) mode.

The data driver 12 supplies the image data from the timing controller 18 to the plurality of data lines DL of the display panel 10 in response to the data control signal from the timing controller 18. The data driver 12 converts digital data input from the timing controller 18 into a positive / negative analog data signal using a gamma voltage, and converts the data signal each time the gate line GL is driven. DL). The data driver 12 includes at least one data IC and is mounted on a circuit film such as TCP, COF, FPC, etc., and attached to the display panel 10 in a tape automatic bonding (TAB) method, or in a chip on glass (COG) method. The display panel 10 may be mounted on the display panel 10.

The gate driver 14 sequentially drives a plurality of gate lines GL formed in the thin film transistor array of the display panel 10 in response to a gate control signal from the timing controller 18. The gate driver 14 supplies a scan pulse of a gate-on voltage for each scan period of each gate line GL, and supplies a gate-off voltage in the remaining periods in which another gate line GL is driven. The gate driver 14 includes at least one gate IC and is mounted on a circuit film such as a tape carrier package (TCP), a chip on film (COF), a flexible print circuit (FPC), and the like, and the tape driver (TAB) on the display panel 10. The display panel 10 may be attached by an automatic bonding method or mounted on the display panel 10 by a chip on glass (COG) method. In addition, the gate driver 14 may be embedded in the display panel 10 in a gate in panel (GIP) manner and formed on the thin film transistor substrate together with the pixel array.

The timing controller 18 processes the image data input from the host computer 50 and supplies it to the data driver 12. For example, the timing controller 18 corrects and outputs data by overdriving driving to add an overshoot value or an undershoot value according to the data difference between adjacent frames in order to improve the response speed of the liquid crystal. can do. In addition, the timing controller 18 uses a plurality of synchronization signals input from the host computer 50, that is, at least two of a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, and a dot clock. A data control signal for controlling the driving timing and a gate control signal for controlling the driving timing of the gate driver 14 are generated. The timing controller 18 outputs the generated data control signal and gate control signal to the data driver 12 and the gate driver 14, respectively. The data control signal includes a source start pulse and a source sampling clock for controlling the latch of the data signal, a polarity control signal for controlling the polarity of the data signal, a source output enable signal for controlling the output period of the data signal, and the like. The gate control signal includes a gate start pulse and a gate shift clock for controlling the scanning of the gate signal, a gate output enable signal for controlling the output period of the gate signal, and the like. The timing controller 18 supplies a synchronization signal (a vertical synchronization signal, a horizontal synchronization signal, etc.) to the touch controller 30 so that the driving timing of the liquid crystal panel 10 and the driving timing of the touch sensor 20 are linked to each other. The drive timing of 30 can be controlled.

The touch sensor 20 senses a user's touch and allows the user to talk to a GUI displayed on the display panel 10. The touch sensor 20 mainly uses a capacitive type touch sensor indicating a change in capacitance generated when a small amount of electric charge moves to a touch point when a human body or a conductor such as a stylus touches the touch point. The touch sensor 20 may be attached on the display panel 10 or embedded in the pixel matrix of the display panel 10.

For example, in the capacitive touch sensor 20 attached to the display panel 10, a plurality of first sensing electrodes 22 arranged in a row direction as shown in FIG. 2 are electrically connected to each other. The plurality of scan lines SL1 to SLn and the plurality of second sensing electrodes 24 arranged in the column direction are electrically connected to each other and have a plurality of readout lines RL1 to RLm. Each of the first and second sensing electrodes 22 and 24 is mainly formed in a rhombus shape and may be formed in various other shapes. The first and second sensing electrodes 22 and 24 are driven by the touch controller 30 to form capacitance by a fringe field, and a capacitor with a conductive touch object that touches the touch sensor 20 is formed. And change the capacitance and output a readout signal indicating the capacitance change to the touch controller 30.

The touch controller 30 sequentially supplies driving pulses to the scan lines SL1 to SLn of the touch sensor 20, and uses the readout signals output from the readout lines RL1 to RLm of the touch sensor 20. Then, it is determined whether the touch is performed by each touch node (by touch pixel or by touch channel), and the touch point coordinates of the detected touch area are detected and supplied to the host computer 50 according to the result.

In particular, the touch controller 30 measures the noise by band pass filtering the readout signal of the touch sensor 20, and adjusts the slew rate of the driving pulse according to the measured noise, thereby adjusting the slew rate according to the noise. To drive the touch sensor 20 using.

The touch controller 30 applies a driving pulse having a complete square wave shape to the touch sensor 20, and the square wave pulse generates a lot of harmonic noise by its pulse width and rising / falling speed. Larger slew rate (smaller rise / fall time) increases harmonic noise, and smaller slew rate (large rise / fall time) reduces harmonic noise.

Accordingly, the touch controller 30 according to the present invention detects noise by using the readout signal of the touch sensor 20 and reduces the noise by adjusting the slew rate of the driving waveform to be reduced according to the presence or absence of the noise. In addition, the touch controller 30 may adjust the slew rate of the driving pulse so that the noise has the smallest slew rate by repeating the operation of adjusting the slew rate while measuring the noise from the readout signal until the noise does not occur within the threshold. . The touch controller 30 always performs the slew rate adjustment operation of the driving pulse through the noise measurement while the touch sensor 20 is being driven, or when the power is turned on, the touch controller 20 is in a state in which no touch occurs. It may optionally be performed in any period or according to a user's indication signal.

The host computer 50 supplies image data and a plurality of synchronization signals to the timing controller 18, analyzes touch point coordinates input from the touch controller 30, and performs a command corresponding to a user's touch operation.

3 is a block diagram showing the configuration of the touch sensing device shown in FIG. 1, FIG. 4 is a circuit block diagram showing the configuration of the slew rate adjusting unit shown in FIG. 3, and FIG. It is a flowchart explaining step-by-step the slew rate adjustment method according to this.

The touch sensing device shown in FIG. 3 includes a touch controller 30 connected to the touch sensor 20. The touch controller 30 includes a driving pulse generator 32, a slew rate adjuster 34, and a touch sensor driver 36 to drive the touch sensor 20. In addition, the touch controller 30 includes a readout circuit 42 and a signal processor 44 to sense a touch from the touch sensor 20, and the noise measurer 40 to control the slew rate adjuster 34. ).

The driving pulse generator 32 generates a driving pulse having a square wave shape and outputs the driving pulse to the slew rate adjusting unit 34.

The slew rate adjusting unit 34 adjusts the slew rate of the square wave driving pulse in response to the square wave driving pulse from the driving pulse generator 32 in response to the selection signal according to the noise level from the noise measuring unit 40.

Specifically, as shown in FIG. 4, the slew rate adjusting unit 34 includes the squares X2, X4, and the square wave driving pulses Tx from the driving pulse generator 32 having different driving strengths. ... outputs a plurality of driving pulses adjusted to have different slew rates using Xn), and different slew rates according to the selection signal SEL from the noise measuring unit 40 in the multiplexer (MUX) 35. By selecting and outputting one of the plurality of driving pulses having the output, the driving pulse having the slew rate adjusted according to the noise is output to the touch sensor driver 36.

The touch sensor driver 36 sequentially supplies the square wave driving pulses of which the slew rate from the slew rate adjusting unit 34 is adjusted to the scan lines SL1 to SLn (FIG. 2) of the touch sensor 20.

The noise measuring unit 40 bands the readout signal output from the readout lines RL1 to RLm (FIG. 2) whenever a driving pulse is supplied to the scan lines SL1 to SLn (FIG. 2) of the touch sensor 20. Noise is detected by pass filtering, and a slew rate selection signal corresponding to the detected noise is generated and output to the slew rate adjusting unit 34.

Specifically, referring to FIG. 5, the noise measuring unit 40 inputs a readout signal output from the touch sensor 20 driven by a driving pulse having a currently determined slew rate (S4), and inputs the readout. Noise is measured by filtering the signal through N band pass filters (BPFs) having N different frequency bands, where N is a natural number (S4).

Next, the noise measuring unit 40 determines whether noise occurs according to the outputs of the N BPFs (S6), and generates and outputs a selection signal for reducing the slew rate of the driving pulse when the noise occurs (S8). If no noise is generated, a selection signal for maintaining the current slew rate is generated and output (S10). In other words, when a high value corresponding to noise detection is detected in a specific BPF filtering the readout signal, the noise measuring unit 40 determines that high harmonic noise is generated, and reduces the slew rate of the driving pulse. The selection signal indicative of a slew rate smaller than the slew rate of the current drive pulse is output to the slew rate adjusting section 34 and returned. On the other hand, if noise is not detected through the filtering of the readout signal (when the output of the BPF is a low value), the noise measuring unit 40 indicates the current slew rate to maintain the slew rate of the current driving pulse. Is output to the slew rate adjusting unit 34 and returned.

On the other hand, when the slew rate is adjusted by the slew rate adjusting unit 34 in response to the selection signal of the noise measuring unit 40, the touch sensor 20 is driven by the adjusted drive pulse, and the noise measuring unit ( 40 repeats steps 2 to 6 (S2 to S6) described above to determine whether noise is generated by band pass filtering the readout signal from the touch sensor 20 again. If it is determined that noise is generated again in this step S6, the noise measuring unit 40 slews the selection signal indicating a slew rate smaller than the slew rate of the current drive pulse (i.e., the slew rate selected by the first adjustment). By outputting to the rate adjusting section 34 and returning, the operation of outputting a selection signal for slew rate adjustment while measuring noise from the readout signal is repeated until noise is not generated within a threshold. Accordingly, the slew rate adjusting unit 34 may adjust the slew rate of the driving pulse to have a slew rate that generates the least noise in response to the control of the noise measuring unit 40.

The readout circuit 42 uses a readout signal output from the readout lines RL1 to RLm (FIG. 2) whenever a driving pulse is supplied to the scan lines SL1 to SLn (FIG. 2) of the touch sensor 20. To detect the sensing data for each touch node. To this end, the readout circuit 42 includes a mutual sensing unit (MSU), an analog-to-digital converter (ADC), and the like. The MSU including the integrator integrates the readout signal from the touch sensor 20 and outputs it as an analog sensing signal. The ADC converts the analog sensing signal from the mutual sensing unit into digital sensing data and outputs it to the signal processor 44.

The signal processor 44 detects a touch region by determining whether the touch is performed for each touch pixel by using the sensing data from the readout circuit 42, and detects touch point coordinates of the detected touch region to host the computer 50. To supply.

6A to 6C are simulation waveforms illustrating a noise reduction result according to a slew rate adjustment of a driving pulse in the touch sensing device according to an exemplary embodiment of the present invention.

When the touch sensor is driven using driving pulses having different slew rates, that is, different rise / fall times (10 ns, 100 ns, 500 ns, and 1000 ns), as shown in FIG. It can be seen that the smaller the slew rate (that is, the larger the rise / fall time), the less the noise of the readout signal of the touch sensor. Accordingly, as shown in FIG. 6C, the smaller the slew rate (that is, the larger the rise / fall time), the greater the integral value output from the MSU increases. As a result, the SNR increases to more accurately sense the touch data. have.

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As described above, the touch sensing device and method according to the present invention measures the noise detected from the readout signal and adjusts the slew rate of the driving pulse according to the measured noise to reduce harmonic noise and increase the SNR to accurately correct the touch signal. You can sense it.

Although illustrated and described in the specific embodiments to illustrate the technical idea of the present invention, the present invention is not limited to the same configuration and operation as the specific embodiment as described above, various modifications do not depart from the technical idea of the present invention It can be implemented within a range. Therefore, such modifications should also be regarded as belonging to the scope of the present invention, and the scope of the present invention should be determined by the claims below.

10: display panel 12: data driver
14: gate driver 16: panel driver
18: timing controller 20: touch sensor
22: first sensing electrode 24: second sensing electrode
30: touch sensing device 32: driving pulse generator
34: slew rate adjusting unit 36: touch sensor drive unit
40: noise measuring unit 42: readout circuit
44: signal processor MSU: Mutual Sensing Unit
ADC: Analog-to-Digital Converter 50: Host Computer

Claims (9)

With touch sensor,
And a touch controller for driving the touch sensor and adjusting a slew rate of a driving pulse for driving the touch sensor according to whether the noise is measured by measuring noise through a readout signal from the touch sensor.
The touch controller
When the readout signal from the touch sensor is filtered through a plurality of band pass filters having different frequency bands and noise is detected by at least one band pass filter, the touch sensor is driven to drive the touch sensor among a plurality of driving pulses having different slew rates. And a drive pulse having a slew rate different from the used drive pulse, and sequentially supplying the selected drive pulse to a plurality of scan lines of the touch sensor to drive the touch sensor. The method according to claim 1,
The touch controller
A driving pulse generator for generating and outputting a square wave driving pulse;
A slew rate adjusting unit which generates the plurality of driving pulses by using the square wave driving pulses supplied from the driving pulse generator, and selects and outputs any one driving pulse corresponding to the input selection signal;
A touch sensor driver configured to sequentially drive the plurality of scan lines of the touch sensor by using a driving pulse supplied from the slew rate adjusting unit;
A noise measuring unit including the plurality of band pass filters and generating the selection signal according to the output of the plurality of band pass filters and outputting the selected signal to the slew rate adjusting unit;
A readout circuit for outputting touch sensing data indicating whether the touch is sensed using the readout signal from the touch sensor;
And a signal processor configured to calculate and output touch coordinates using the touch sensing data from the readout circuit. The method according to claim 2,
The noise measuring unit
Detecting the noise and outputting the selection signal for selecting a driving pulse having a slew rate different from the driving pulse used to drive the touch sensor,
And a touch sensing device for outputting a selection signal for maintaining a driving pulse used to drive the touch sensor if the noise is not detected. The method according to claim 3,
The slew rate adjusting unit
A plurality of inverters for outputting a plurality of driving pulses having different slew rates by adjusting the square wave driving pulses from the driving pulse generator to have different slew rates through different driving intensities;
And a multiplexer for selecting and outputting one of driving pulses output from the plurality of inverters in response to the selection signal. The method according to claim 1,
The touch controller
The noise is measured from the readout signal of the touch sensor, and when the noise is detected, the operation of adjusting the slew rate of the driving pulse is repeated until the noise does not occur within a threshold value in the readout signal,
The slew rate adjustment operation of the driving pulse is performed while driving the touch sensor, when the power is turned on, during a period in which no touch occurs in the touch sensor, or according to a user's instruction. . A first step of driving the touch sensor using a driving pulse;
A second step of measuring noise by filtering the readout signal from the driven touch sensor, and adjusting the slew rate of the driving pulse according to a measurement result of the noise,
The second step is
When the readout signal from the touch sensor is filtered through a plurality of band pass filters having different frequency bands and noise is detected by at least one band pass filter, the touch sensor is driven to drive the touch sensor among a plurality of driving pulses having different slew rates. Selecting a driving pulse having a slew rate different from the used driving pulse, and sequentially supplying the selected driving pulse to a plurality of scan lines of the touch sensor to drive the touch sensor. The method according to claim 6,
The second step is
Generating and outputting a square wave driving pulse;
Outputting the plurality of driving pulses having different slew rates through the plurality of inverters having different driving intensities from the square wave driving pulses;
Generating and outputting a selection signal for selecting any one of a plurality of driving pulses having different slew rates according to the noise detection result;
Selecting and outputting one of a plurality of driving pulses having different slew rates in response to the selection signal,
Generating and outputting the selection signal and selecting and outputting one of the plurality of driving pulses
When the noise detection signal is output, selecting and outputting a driving pulse having a slew rate different from the driving pulse used to drive the touch sensor;
And a driving pulse used to drive the touch sensor unit when the noise is not detected. delete The method according to claim 6,
If the noise is detected, repeating the first and second steps until the noise does not occur within a threshold value in the readout signal to adjust the slew rate of the driving pulse.

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