KR102235094B1 - Touch system, touch sensing controller and stylus pen adapted thereto - Google Patents

Abstract

In detail, a touch system capable of simultaneously realizing finger touch recognition and pen touch recognition, and multi-touch recognition of stylus pens, and a touch sensing controller and stylus pen employed therein are disclosed. The touch system includes a touch panel, a stylus pen, and a touch sensing controller. The touch panel includes a plurality of driving electrodes and a plurality of sensing electrodes. The stylus pen provides a pen frequency signal set to sense the position of the stylus pen and the pressure of the stylus pen to the touch panel. The touch sensing controller outputs a plurality of driving signals having different frequency components to the touch panel, and at least one of a touch coordinate of a finger and a touch coordinate of the stylus pen based on a plurality of sensing signals received from the touch panel. Identify more than one.

Description

Touch system and touch sensing controller and stylus pen employed therein {TOUCH SYSTEM, TOUCH SENSING CONTROLLER AND STYLUS PEN ADAPTED THERETO}

The present invention relates to a touch system, a touch sensing controller and a stylus pen employed therein, and more particularly, to a touch system capable of simultaneously realizing finger touch recognition and pen touch recognition, and realizing multi-touch recognition of stylus pens. It relates to an adopted touch sensing controller and a stylus pen.

The use of touch screen interfaces and styli is widely established. Touch screen designs incorporate a number of different technologies including resistive, capacitive, inductive, and radio frequency sensing arrays. For example, resistive touch screens are passive devices well suited for use with a passive stylus.

Although resistive touch screens can detect input from any nearby object, multi-touch is generally not supported. An example of a multi-touch application may be applying two or more fingers to a touch screen. Another example may be entering a signature including simultaneous palm and stylus input signals. Due to these and many other shortcomings, capacitive touch screens are increasingly replacing resistive touch screens in the customer market.

Various connected active stylus approaches have been implemented for use with touch screens and in many customer applications such as store terminals (e.g., signature pads used for credit card transactions in retail stores) and other public uses. Was found. However, the need for a connectable cable is a significant drawback for personal applications such as personal computers ("PCs"), smart phones, and tablet PCs.

Korean Patent Laid-Open Publication No. 2012-0095376 (Name: Multi-touch touch device having multiple driving frequencies and maximum likelihood estimation) (published on August 28, 2012) Korean Patent Laid-Open Patent No. 2011-0134886 (Name: Multi-function capacitance sensing circuit with current conveyor) (published on December 15, 2011)

Accordingly, the technical problem of the present invention is to provide a touch system capable of simultaneously realizing finger touch recognition and pen touch recognition, and multi-touch recognition of stylus pens.

Another object of the present invention is to provide a touch sensing controller employed in the above-described touch system.

Another object of the present invention is to provide a stylus pen employed in the above-described touch system.

In order to realize the object of the present invention, a touch system according to an embodiment includes a touch panel, a stylus pen, and a touch sensing controller. The touch panel includes a plurality of driving electrodes and a plurality of sensing electrodes. The stylus pen provides a pen frequency signal set to sense the position of the stylus pen and the pressure of the stylus pen to the touch panel. The touch sensing controller outputs a plurality of driving signals having different frequency components to the touch panel, and at least one of a touch coordinate of a finger and a touch coordinate of the stylus pen based on a plurality of sensing signals received from the touch panel. Identify more than one.

In order to realize another object of the present invention described above, a touch sensing controller according to an embodiment includes a touch driver, a touch sensing unit, and a touch determination unit. The touch driver is connected to the driving electrodes of the touch panel in contact with the stylus pen that outputs a mixing signal in which a position detection signal set to detect the position of the stylus pen and a pressure detection signal set to detect the pressure of the stylus pen are mixed. And outputs the driving signals to the driving electrodes. The touch sensing unit is connected to sensing electrodes of the touch panel and receives the sensing signals through the sensing electrodes. The touch determination unit determines at least one of a touch coordinate of a finger and a touch coordinate of the stylus pen based on the sensing signals.

In order to realize another object of the present invention, a stylus pen according to an embodiment includes a conductive tip, a pressure sensor, a frequency signal generator, and a mixer. The conductive tip may contact the touch panel. The pressure sensor measures the pressure of the conductive tip applied to the touch panel and outputs a pen pressure signal. The frequency signal generator generates a pressure sensing signal based on the pen pressure signal, and generates a position sensing signal set to detect the position of the stylus pen. The mixer provides a mixing signal to the conductive tip by mixing the position detection signal and the pressure detection signal.

According to such a touch system and a touch sensing controller and a stylus pen employed therein, a plurality of driving signals having different frequency components are output to the touch panel, and a finger is touched based on a plurality of sensing signals received from the touch panel. By discriminating at least one of the coordinates and the touch coordinates of the stylus pen, finger touch recognition and pen touch recognition can be simultaneously realized. In addition, differently from the frequency of the driving signal applied to the touch panel, the stylus pen is designed to apply to the touch panel by setting the frequency of the pen frequency signal to sense the position of the stylus pen and the pressure of the stylus pen. The pen can be used on one touch panel.

1 is a schematic diagram illustrating a touch system according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of determining touch coordinates by the touch sensing device illustrated in FIG. 1.
3A is a schematic diagram for explaining the appearance of the stylus pen shown in FIG. 1, and FIG. 3B is a configuration diagram for schematically describing the stylus pen shown in FIG. 1.
4 is a block diagram illustrating the stylus pen shown in FIG. 1.
5 is a waveform diagram illustrating an example of a position detection signal and a pressure detection signal output from the stylus pen shown in FIG. 1.
6 is a circuit diagram illustrating an example of the stylus pen shown in FIG. 1.
7 is a circuit diagram illustrating another example of the stylus pen shown in FIG. 1.
8A is a schematic diagram of a touch panel for explaining a touch by a finger, and FIG. 8B is a waveform diagram for explaining touch coordinate recognition through frequency spectrum analysis of a sensing signal by a finger touch.
9A is a schematic diagram of a touch panel for explaining touch by a stylus pen, and FIG. 9B is a waveform diagram for explaining touch coordinate recognition through frequency spectrum analysis of a sensing signal by a stylus pen.
10A is a schematic diagram of a touch panel for explaining touch by a finger and a stylus pen, and FIG. 10B is a waveform diagram for explaining touch coordinate recognition through frequency spectrum analysis of a sensing signal by a finger and a stylus pen.
11A and 11B are configuration diagrams of a touch sensing device for describing touch coordinate recognition of a finger and a stylus pen.
12 is a flowchart illustrating a touch coordinate recognition method in which a finger and a stylus pen are individually recognized in the touch sensing device illustrated in FIGS. 11A and 11B.
13 is a flowchart illustrating a method of recognizing touch coordinates in which a finger and a stylus pen are simultaneously recognized in the touch sensing device illustrated in FIGS. 11A and 11B.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. In the present invention, various modifications may be made and various forms may be applied, and specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific form disclosed, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing each drawing, similar reference numerals have been used for similar elements. In the accompanying drawings, the dimensions of the structures are shown to be enlarged than the actual size for clarity of the present invention.

Terms such as first and second may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance the possibility of being added.

In addition, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. Does not.

1 is a schematic diagram illustrating a touch system according to an embodiment of the present invention. In particular, it is a schematic diagram for explaining simultaneous use of a stylus pen and a finger on a touch panel.

Referring to FIG. 1, a touch system includes a touch sensing device 100 and a stylus pen 200, and recognizes a user's touch operation of a finger 300 or a touch operation of the stylus pen 200. The touch sensing device 100 detects the position of the user's finger 300 to determine the touch coordinates of the finger 300 or detects the position of the stylus pen 200 to determine the touch coordinates of the stylus pen 200. Discriminate. The touch coordinates of the finger 300 and the touch coordinates of the stylus pen 200 may be detected at the same time.

FIG. 2 is a diagram illustrating a configuration of determining touch coordinates by the touch sensing device illustrated in FIG. 1.

1 and 2, a plurality of driving signals are applied to different driving electrodes provided in the touch panel. Each of the driving signals has a different frequency component. Hereinafter, for convenience of explanation, it will be described as an example that the first driving signal STX0, the second driving signal STX1, the third driving signal STX2, and the fourth driving signal STX3 are applied to the touch panel. Accordingly, the first driving signal STX0 has a first frequency component f0, the second driving signal STX1 has a second frequency component f1, and the third driving signal STX2 has a third frequency It has a component f2, and the fourth drive signal STX3 has a fourth frequency component f3. Each of the first to fourth frequency components f0, f1, f2, and f3 is different from each other.

A sensing signal SRX sensed in response to driving signals STX0, STX1, STX2, and STX3 is received by the sensing electrode RX of the touch panel. The sensing signal is mixed by the touch panel, but the amplitude is attenuated compared to the driving signals STX0, STX1, STX2, and STX3.

The sensing signal SRX is amplified by an amplifier and then provided to the FFT processing block. The FFT-processed sensing signals are decomposed and analyzed to derive the coordinates of where the touch occurred. The amplifier or FFT processing block may be provided in a touch sensing controller provided in the touch sensing device 100.

FIG. 3A is a schematic diagram for explaining the appearance of the stylus pen shown in FIG. 1, and FIG. 3B is a configuration diagram for schematically describing the stylus pen shown in FIG. 1.

3A and 3B, the stylus pen 200 includes a pencil-shaped conductive case 202, a conductive tip 204 connected to one side of the conductive case 202, the conductive case 202 and the conductive tip. It includes a pressure sensor 206, a frequency signal generator 208 and a mixer 210 disposed between 204.

The conductive tip 204 has a shape capable of contacting the touch panel.

The pressure sensor 206 measures the pressure of the conductive tip 204 applied to the touch panel and outputs a pen pressure signal. That is, the pressure sensor 206 generates an electric signal according to the pressure applied to the conductive tip 204 protruding from the end of the stylus pen body. For example, the pressure sensor 206 generates an electric signal according to the pressure applied to the conductive tip 204 by the user's writing motion. To this end, the conductive tip 204 may be connected to the pressure sensor 206 to transmit the pressure generated in the conductive tip 204 to the pressure sensor 206.

The frequency signal generator 208 generates a position detection signal SPO set to detect the position of the stylus pen 200, and a pressure detection signal SPR set to measure the pen pressure of the stylus pen based on the pen pressure signal. ). Hereinafter, in the present specification, an example in which four driving electrodes and four sensing electrodes are disposed on a touch panel for convenience of description will be described. At this time, a first driving signal STX0, a second driving signal STX1, a third driving signal STX2, and a fourth driving signal STX3 are applied to each of the driving electrodes. Accordingly, the first driving signal STX0 has a first frequency component f0, the second driving signal STX1 has a second frequency component f1, and the third driving signal STX2 is It has a third frequency component f2, and the fourth driving signal STX3 has a fourth frequency component f3. Each of the first to fourth frequency components f0, f1, f2, and f3 is different from each other. In addition, the fifth frequency component f4 of the position detection signal SPO and the sixth frequency component f5 of the pressure detection signal SPR are the first to fourth frequency components f0, f1, f2, f3) different from each.

The mixer 210 mixes the position detection signal SPO and the pressure detection signal SPR and outputs a mixing signal to the conductive tip 204.

As described above, differently from the frequency of the driving signal applied to the touch panel, the stylus pen is designed to apply to the touch panel by setting the frequency of the pen frequency signal to sense the position of the stylus pen and the pressure of the stylus pen. Thus, multiple stylus pens can be used on one touch panel.

4 is a block diagram illustrating the stylus pen 200 shown in FIG. 1.

4, the stylus pen 200 includes buttons 250, a button processing unit 252, a pen control unit 260, a pen pressure sensor 206, a pen pressure processing unit 207, a pen control unit 260, and a power management unit. 270, a battery 272, a waveform generator 280, and a waveform driver 290.

The buttons 250 are varied according to a user's manipulation to provide a button signal to the button processing unit 252. The buttons 250 may be mechanical buttons or electrostatic buttons. The buttons 250 may provide additional functions, including, but not limited to, “left click” and “right click” functions, similar to functions of a computer mouse. The buttons 250 of the stylus pen 200 may be coupled to the pen control unit (CPU) 260. Buttons 250 may be of mechanical, electrical, capacitive, or other types known to those skilled in the art.

The button processing unit 252 digitally converts button signals provided from the buttons 250 and provides the digitally converted button signals to the pen control unit 260.

The pen pressure sensor 206 senses the pressure applied to the touch panel by the stylus pen 200 and provides the sensed pressure signal to the pen pressure processing unit 207.

The pen pressure processing unit 207 provides a pressure signal provided from the pen pressure sensor 206 to the waveform driving unit 280.

The pen control unit 260 may control operations of components included in the stylus pen 200.

The power management unit 270 supplies power from the battery 272 to each of the components. If necessary, the power is boosted, and the boosted power is supplied to each component. Typically, stylus pens can be classified into active type or passive type stylus pens depending on the presence or absence of a battery. According to the present invention, since the battery 272 is provided in the stylus pen 200, the stylus pen according to the present invention is an active stylus pen.

The waveform generator 280 generates a first waveform for generating a position detection signal SPO or a second waveform for generating a pressure detection signal SPR in response to the control of the pen control unit 260. Provided at 290. The first waveform or the second waveform may be a sine file.

The waveform driver 290 amplifies the first waveform or the second waveform generated by the waveform generator 280, respectively, and outputs a mixing signal by mixing the amplified waveforms. In this embodiment, the pen pressure processing unit 207, the waveform generator 280, and the waveform driver 290 may define the frequency signal generator 208 shown in FIG. 3.

5 is a waveform diagram illustrating an example of a position detection signal SPO and a pressure detection signal SPR output from the stylus pen shown in FIG. 1.

Referring to FIG. 5, the fifth frequency component f4 of the position detection signal SPO is the first to fourth frequency components f0, f1, f2, and f3 of the driving signal provided to the driving electrodes of the touch panel. It is set differently from. In addition, the sixth frequency component f5 of the pressure sensing signal SPR is set differently from the first to fourth frequency components f0, f1, f2, and f3 of the driving signal provided to the driving electrodes of the touch panel. . In addition, the fifth frequency component f4 of the position detection signal SPO and the sixth frequency component f5 of the pressure detection signal SPR are set differently from each other.

The position detection signal SPO has a fixed frequency and a fixed amplitude.

The pressure detection signal SPR has a fixed frequency and a variable amplitude. The amplitude of the pressure sensing signal SPR may be varied according to a pen pressure signal corresponding to a pressure applied to the stylus pen. For example, when a high pen pressure signal is detected, a pressure detection signal SPR having a maximum amplitude may be output, and when a low pen pressure signal is detected, a pressure detection signal SPR having a minimum amplitude may be output.

Meanwhile, the amplitude of the pressure detection signal SPR may be varied according to a button that can be operated by a user. The button is provided on the stylus pen, and the amplitude may vary according to the provided button.

6 is a circuit diagram illustrating an example of a waveform generator and a waveform driver shown in FIG. 4.

6, the waveform generator 280 includes a fifth frequency signal generator 282 and a sixth frequency signal generator 284, and the waveform driver 290 includes a first amplifier 292 and a second It includes an amplification unit 294, a mixer 210, and a conductive tip 204.

The first amplifier 292 includes a first resistor R1, a second resistor R2, and a first operational amplifier OP1. One end of the first resistor R1 receives a position detection signal SPO, and the other end of the first resistor R1 is connected to an inverting end of the first operational amplifier OP1. One end of the second resistor R2 is connected to the other end of the first resistor R1 and the inverting end of the first operational amplifier OP1, and the other end of the second resistor R2 is connected to the mixer 210. do. The second resistor R2 may be a variable resistor. The inverting end of the first operational amplifier OP1 is connected to the other end of the first resistor R1 and one end of the second resistor R2, and the non-inverting end of the first operational amplifier OP1 is a reference voltage ( Vref) is received.

The second amplifier 294 includes a third resistor R3, a fourth resistor R4, and a second operational amplifier OP2. One end of the third resistor R3 receives a position detection signal SPO, and the other end of the third resistor R3 is connected to an inverting end of the second operational amplifier OP2. One end of the fourth resistor R4 is connected to the other end of the third resistor R3 and the inverting end of the second operational amplifier OP2, and the other end of the fourth resistor R4 is connected to the mixer 210. do. The fourth resistor R4 may be a variable resistor. The inverting end of the second operational amplifier OP2 is connected to the other end of the third resistor R3 and one end of the fourth resistor R4, and the non-inverting end of the second operational amplifier OP2 is a reference voltage ( Vref) is received.

The mixer 210 includes a fifth resistor R5, a sixth resistor R6, a third operational amplifier OP3, and a seventh resistor R7. One end of the fifth resistor R5 is connected to an output terminal of the first amplifier, and the other end of the fifth resistor R5 is connected to an inverting terminal of the third operational amplifier OP3. One end of the sixth resistor R6 is connected to an output terminal of the second amplifier, and the other end of the sixth resistor R6 is connected to an inverting terminal of the third operational amplifier OP3. The seventh resistor R7 is connected to an inverting terminal and an output terminal of the third operational amplifier OP3. The inverting end of the third operational amplifier OP3 is connected to the other end of the fifth resistor R5 and the other end of the sixth resistor R6, and the non-inverting end of the third operational amplifier OP3 is a reference voltage ( Vref) is received.

In the above, it has been described that the position detection signal SPO and the pressure detection signal SPR are separately generated, the generated signals are amplified, and then mixed to provide the pen frequency signal to the conductive tip.

7 is a circuit diagram illustrating another example of a waveform generator and a waveform driver shown in FIG. 4.

Referring to FIG. 7, the waveform generator 280 may include a digital function generator that provides a sine wave to the waveform driver 290. The digital function generator is configured to precisely generate a sine wave with an accurate frequency, period, and phase in response to the control of the fan control unit 260 (shown in FIG. 4). ) Modules can be included.

Each of the DDS modules may generate a plurality of frequency signals. For example, a position detection signal SPO having a fifth frequency component f4 and a pressure detection signal SPR having a sixth frequency component f5 may be generated. Also, a signal having a frequency component fn-1, a signal having a frequency component fn, and the like may be generated. Here, the signal having the frequency component fn-1 may be a frequency component corresponding to the first button provided in the stylus pen, and the signal having the frequency component fn corresponds to the second button provided in the stylus pen. It may be a frequency component.

The waveform driver 290 includes a first resistor R1, a second resistor R2, and a first operational amplifier OP1. One end of the first resistor R1 receives a sinusoidal signal from the waveform generator 280, and the other end of the first resistor R1 is connected to an inverting end of the first operational amplifier OP1. One end of the second resistor R2 is connected to the other end of the first resistor R1 and the inverting end of the first operational amplifier OP1, and the other end of the second resistor R2 is connected to the conductive tip 204. Connected. The second resistor R2 may be a variable resistor. The inverting end of the first operational amplifier OP1 is connected to the other end of the first resistor R1 and one end of the second resistor R2, and the non-inverting end of the first operational amplifier OP1 is a reference voltage ( Vref) is received.

8A is a schematic diagram of a touch panel for explaining a touch by a finger, and FIG. 8B is a waveform diagram for explaining touch coordinate recognition through frequency spectrum analysis of a sensing signal by a finger touch.

8A, a first driving electrode TX0, a second driving electrode TX1, a third driving electrode TX2, and a fourth driving electrode TX3 are disposed in a horizontal direction on the touch panel, and the first sensing electrode is The electrode RX0, the second sensing electrode RX1, the third sensing electrode RX2, and the fourth sensing electrode RX3 are disposed in the vertical direction. The first to fourth driving electrodes TX0, TX1, TX2, and TX3 are disposed in a lower area, and the first to fourth sensing electrodes RX0, RX1, RX2, and RX3 are disposed in an upper area.

Each of the first driving electrode TX0, the second driving electrode TX1, the third driving electrode TX2, and the fourth driving electrode TX3 has a first driving signal STX0 and a second driving signal ( STX1), a third driving signal STX2, and a fourth driving signal STX3 are applied. In response to the applied driving signals STX0, STX1, STX2, STX3, the sensing signals SRX0, SRX1, SRX2, SRX3 are the first sensing electrode RX0, the second sensing electrode RX1, and the third sensing electrode. It is received through each of the (RX2) and the fourth sensing electrode (RX3). The received sensing signals are subjected to FFT processing to determine touch coordinates.

Referring to FIG. 8B, a sensing signal received through the second sensing electrode RX1 is subjected to FFT processing.

In the case of the base state without a touch operation, the FFT-processed sensing signal is the first frequency component (f0), the second frequency component (f1), the third frequency component (f2), and the fourth frequency component ( has f3). In this case, the amplitudes of the first to fourth frequency components f0, f1, f2, and f3 are the same.

In the case of a touch state in which a finger touches an area where the second driving electrode TX1 and the second sensing electrode RX1 intersect, the FFT-processed sensing signal is the first frequency component f0 when observed in the frequency spectrum. , A second frequency component f1, a third frequency component f2, and a fourth frequency component f3. At this time, the amplitudes of the first frequency component f0, the third frequency component f2, and the fourth frequency component f3 are the same. The amplitude of the second frequency component f1 is smaller than the amplitude of the first frequency component f0.

When the waveform of the finger touch state is subtracted from the waveform of the base state, only the second frequency component f1 remains. The amplitude of the second frequency component f1 remaining after subtraction may correspond to the finger touch sensitivity.

Accordingly, since the second frequency component f1 is detected in response to the second sensing electrode RX1, the second driving electrode transmitting the second driving signal STX1 having the second frequency component f1 (TX1) and the second sensing electrode RX1 are detected as touch coordinates of the finger.

9A is a schematic diagram of a touch panel for explaining touch by a stylus pen, and FIG. 9B is a waveform diagram for explaining touch coordinate recognition through frequency spectrum analysis of a sensing signal by a stylus pen.

Since the touch panel illustrated in FIG. 9A has been described in FIG. 8B, a description thereof will be omitted.

Referring to FIG. 9B, a sensing signal received through the second sensing electrode RX1 is subjected to FFT processing.

In the case of the base state without a touch operation, the FFT-processed sensing signal is the first frequency component (f0), the second frequency component (f1), the third frequency component (f2), and the fourth frequency component ( has f3). In this case, the amplitudes of the first to fourth frequencies f0, f1, f2, and f3 are the same.

In the case of a touch state in which the stylus pen touches a region where the second driving electrode TX1 and the second sensing electrode RX1 intersect, the FFT-processed sensing signal is the first frequency component (f0) when observed on the frequency spectrum. ), a second frequency component f1, a third frequency component f2, a fourth frequency component f3, a fifth frequency component f5, and a sixth frequency component f6. In this case, the amplitudes of the first to fourth frequencies f0, f1, f2, and f3 are the same. The amplitude of the fifth frequency component f5 is smaller than the amplitude of the first frequency component f0. The amplitude of the sixth frequency component f6 is smaller than the amplitude of the first frequency component f0. The amplitude of the sixth frequency component f6 is smaller than the amplitude of the fifth frequency component f5.

When the waveform in the stylus pen touch state is subtracted from the waveform in the base state, only the fifth frequency component f5 and the sixth frequency component f6 remain. The amplitude of the fifth frequency component f5 remaining after subtraction may correspond to the touch sensitivity of the stylus pen. In addition, the amplitude of the sixth frequency component f6 remaining after subtraction may correspond to the pen pressure sensitivity of the stylus pen.

Accordingly, since the fifth frequency component f5 is detected in correspondence with the second sensing electrode RX1, it can be confirmed that the stylus pen is disposed on the second sensing electrode RX1. Accordingly, the second sensing electrode RX1 is detected as the first axis coordinate (eg, X coordinate) of the stylus pen.

Touch coordinates by the stylus pen can be recognized in the above-described manner, and a more detailed description will be given with reference to FIGS. 11A to 13 to be described later.

10A is a schematic diagram of a touch panel for explaining touch by a finger and a stylus pen, and FIG. 10B is a waveform diagram for explaining touch coordinate recognition through frequency spectrum analysis of a sensing signal by a finger and a stylus pen.

Since the touch panel illustrated in FIG. 10A has been described in FIG. 8B, a description thereof will be omitted.

Referring to FIG. 10B, a sensing signal received through the second sensing electrode RX1 is subjected to FFT processing.

In the case of the base state without a touch operation, the FFT-processed sensing signal is the first frequency component (f0), the second frequency component (f1), the third frequency component (f2), and the fourth frequency component ( has f3). In this case, the amplitudes of the first to fourth frequencies f0, f1, f2, and f3 are the same.

A finger touches a region where the second driving electrode TX1 and the second sensing electrode RX1 intersect, and a stylus pen crosses the third driving electrode TX2 and the second sensing electrode RX1. In the case of a mixed touch state that touches an area, the FFT-processed sensing signal is the first frequency component (f0), the second frequency component (f1), the third frequency component (f2), and the fourth frequency component when observed on the frequency spectrum. (f3), a fifth frequency component (f5), and a sixth frequency component (f6). At this time, the amplitudes of the first frequency component f0, the third frequency component f2, and the fourth frequency component f3 are the same. The amplitude of the second frequency component f1 is smaller than the amplitude of the first frequency component f0. The amplitude of the fifth frequency component f5 is smaller than the amplitude of the first frequency component f0. The amplitude of the sixth frequency component f6 is smaller than the amplitude of the first frequency component f0. The amplitude of the sixth frequency component f6 is smaller than the amplitude of the fifth frequency component f5.

When the mixed state waveform is subtracted from the base state waveform, only the second frequency component f1, the fifth frequency component f5, and the sixth frequency component f6 remain. The amplitude of the second frequency component f1 remaining after subtraction may correspond to the finger touch sensitivity. In addition, the amplitude of the fifth frequency component f5 remaining after subtraction may correspond to the touch sensitivity of the stylus pen. In addition, the amplitude of the sixth frequency component f6 remaining after subtraction may correspond to the pen pressure sensitivity of the stylus pen.

Therefore, since the second frequency component f1 is detected in correspondence with the second sensing electrode RX1, the second driving electrode transmitting the second driving signal STX1 having the second frequency component f1 (TX1) and the second sensing electrode RX1 are detected as touch coordinates of the finger. In addition, since the fifth frequency component f5 is detected in correspondence with the second sensing electrode RX1, it can be seen that the stylus pen is disposed on the second sensing electrode RX1. Accordingly, the second sensing electrode RX1 is detected as the coordinate of the first axis of the stylus pen.

In the above-described manner, touch coordinates by a finger and touch coordinates by a stylus pen can be recognized, and a more detailed description will be given with reference to FIGS. 11A to 13.

11A and 11B are configuration diagrams of a touch sensing device for describing touch coordinate recognition of a finger and a stylus pen. In particular, FIG. 11A is a configuration diagram of a touch sensing device for explaining sensing of finger coordinates, X coordinates of a stylus pen, and pen pressure information of a stylus pen. It is a configuration diagram of a touch sensing device for explaining.

11A and 11B, the touch panel 110 includes a first driving electrode TX0, a second driving electrode TX1, a third driving electrode TX2, and a fourth driving electrode TX3 disposed in a horizontal direction. ), and a first sensing electrode RX0, a second sensing electrode RX1, a third sensing electrode RX2, and a fourth sensing electrode RX3 disposed in a vertical direction. For convenience of explanation, a touch panel 110 of a 4x4 electrode matrix in which four driving electrodes and four sensing electrodes are disposed is shown.

In the touch panel 110, driving electrodes are arranged orthogonally to cross and overlap each of the sensing electrodes. Accordingly, each of the driving electrodes is capacitively coupled to each of the sensing electrodes. For example, the second driving electrode TX1 is capacitively coupled to the second sensing electrode RX1 at a point where the second driving electrode TX1 and the second sensing electrode RX1 overlap. The intersections of the driving electrodes and the sensing electrodes form a capacitive sensing element, respectively.

Due to the capacitive coupling between the driving electrode and the sensing electrodes, application of a driving signal at each driving electrode induces a current in each of the sensing electrodes. For example, when a driving signal is applied to the second driving electrode TX1, the driving signal induces a sensing signal from the touch panel 110 on the second sensing electrode RX1. Thereafter, the sensing signals on each of the sensing electrodes may be sequentially measured by using a multiplexer to sequentially connect each of the sensing electrodes to the demodulation circuit. The capacitance associated with each intersection point between the driving electrode and the sensing electrode can be detected by selecting for each available combination of the driving electrode and the sensing electrode.

When a touch object such as a finger or stylus approaches the touch panel 110, the object causes a decrease in capacitance, which affects only some of the electrodes. For example, if the finger is located near the intersection of the second driving electrode TX1 and the second sensing electrode RX1, the presence of the finger reduces the coupling capacitance between the two electrodes TX1 and RX1. In another embodiment, the presence of a finger increases the coupling capacitance between the two electrodes TX1 and RX1. Accordingly, the position of the finger on the touch panel 110 can be determined by identifying a sensing electrode having a reduced coupling capacitance between a driving electrode to which a driving signal is applied and a sensing electrode when the reduced capacitance is measured on the sensing electrode. . Accordingly, by sequentially determining the capacitances associated with each intersection point of the electrodes in the touch panel 110, the positions of one or more inputs may be determined.

In this embodiment, the driving electrodes and sensing electrodes appear as bars or elongated rectangles, but alternative embodiments are diamond, rhombus, chevron, and as will be understood by those skilled in the art having the benefit of this disclosure. Various mosaic shapes may be used, such as other available shapes.

The touch sensing controller 120 outputs a plurality of driving signals having different frequency components to the touch panel 110, and based on the plurality of sensing signals received from the touch panel 110, the touch coordinates and stylus of the finger At least one or more of the touch coordinates of the pen are determined. The touch sensing controller 120 may be implemented in the form of one or a plurality of chips.

The touch sensing controller 120 includes a touch driver 122, a touch sensing unit 124, a touch determination unit 126, and a touch control unit 128.

The touch driver 122 is the driving electrodes TX0, TX1, TX2, TX3 of the touch panel 110 in contact with the stylus pen that outputs a pen frequency signal set to sense the position of the stylus pen and the pressure of the stylus pen. Is connected to, and outputs the driving signals to the driving electrodes TX0, TX1, TX2, and TX3.

The touch driver 122 includes a transmission signal generation unit 1222 and a transmission mux unit 1224. The transmission signal generator 1222 includes a plurality of transmission signal generators that generate driving signals having different frequency components.

The transmission mux unit 1224 includes a first transmission input terminal 0 connected to the transmission signal generator, a second transmission input terminal 1 connected to the touch sensing unit 124, and a plurality of transmission output terminals connected to the driving electrode. Transmitting muxes are included, and in response to a mux control signal MUXC provided from the touch controller 128, the first transmission input terminal and the transmission output terminal are connected, or the second transmission input terminal and the transmission output terminal are connected.

The touch sensing unit 124 is connected to the sensing electrodes RX0, RX1, RX2, and RX3 of the touch panel 110, and receives the sensing signals through the sensing electrodes RX0, RX1, RX2, and RX3. Receive.

The touch sensing unit 124 includes a receiving mux unit 1242, a receiving sensing unit 1244, an analog-digital converting unit 1246, and a fast Fourier transforming unit 1248.

The receiving mux unit 1242 is a receiving output terminal, a first receiving input terminal (0) connected to the sensing electrode, a second receiving terminal connected to the second transmitting input terminal (1) of the transmitting mux unit 1224 of the touch driver 122 A plurality of reception muxes having an input terminal 1 are included, and in response to the mux control signal MUXC, the first reception input terminal is connected to the reception output terminal or the second reception input terminal is connected to the reception output terminal.

The reception sensing unit 1244 includes a plurality of reception sensors connected to the reception output terminals of the reception muxes.

The analog-to-digital conversion unit 1246 digitally converts the sensing signals received through the reception sensors and provides them to the high-speed Fourier conversion unit 1248. The analog-to-digital conversion unit 1246 may perform ADC conversion at a frequency that is at least twice or more faster than the driving frequency.

The fast Fourier transform unit 1248 converts each of the sensing signals from a time domain to a frequency domain by converting the sensing signals digitally converted by the analog-to-digital conversion unit 1246 into a fast Fourier transform. Thus, the frequency component and the amplitude of the frequency component are obtained and then provided to the touch discriminating unit 126. In this embodiment, it is very useful for digital signal processing by converting sensing in the time domain to sensing in the frequency domain.

The touch discrimination unit 126 includes at least one of the touch coordinates of the finger, the touch coordinates of the stylus pen, and the pen pressure information of the stylus pen based on the amount of change between the frequency amplitudes of the high-speed Fourier transformed sensing signal based on the frequency amplitude of the driving signal Identify more than one.

The touch controller 128 controls the operation of the touch driver 122 so that driving signals having different frequency components are simultaneously provided to each of the driving electrodes.

The touch control unit 128 transmits information on the frequency of the driving signal to the analog-to-digital converter 1246 so that the analog-to-digital converter 1246 converts analog-to-digital at a frequency faster than the frequency of the driving signal. to provide.

In this embodiment, the touch sensing controller 120 further includes one or more memory devices (not shown) for storing the measured size and associated parameters, and a microprocessor (not shown) for performing necessary calculation and control functions. I can.

In order to perform one or more of the functions described herein, the touch sensing controller 120 and/or other parts of the touch sensing device 100 may include one or more application-specific integrated circuits (ASICs) and ASSPs. It can be implemented as (application-specific standard product).

In operation, as shown in FIG. 11A, in response to the mux control signal MUXC, the first input terminal 0 of the transmitting mux and the driving electrode are connected to each other, and the first input terminal 0 of the receiving mux And the receiving sensing unit 1244 are connected to each other to sense the touch coordinates of the finger, the first axis coordinates of the stylus pen, and the pen pressure information of the stylus pen. In FIG. 11A, since the sensing electrodes RX0, RX1, RX2, and RX3 are arranged along the X-axis, the coordinate of the first axis of the stylus pen is the X coordinate.

In addition, as shown in FIG. 11B, in response to the mux control signal MUXC, the second input terminal 1 of the transmitting mux and the driving electrode are connected to each other, and the second input terminal 1 of the receiving mux is connected to each other. The receiving and sensing units 1244 are connected to each other to sense the coordinates of the second axis of the stylus pen and pen pressure information of the stylus pen. In FIG. 11B, since the driving electrodes TX0, TX1, TX2, and TX3 are arranged along the Y-axis, the coordinates of the second axis of the stylus pen are Y coordinates.

As described above, the touch sensing controller 120 outputs a plurality of driving signals having different frequency components to the touch panel 110, and receives a plurality of sensing signals received from the touch panel 110. By discriminating at least one of the touch coordinates of the finger and the touch coordinates of the stylus pen based on the basis, finger touch recognition and pen touch recognition can be simultaneously realized.

12 is a flowchart illustrating a touch coordinate recognition method in which a finger and a stylus pen are individually recognized in the touch sensing device illustrated in FIGS. 11A and 11B.

11A, 11B, and 12, the mux is set to 0 (step S100). That is, the first transmission input terminal 0 of the transmission mux provided in the transmission mux part 1224 and the driving electrodes TX0, TX1, TX2, TX3 are connected to each other, and provided in the reception mux part 1242 The first receiving input terminal 0 of the receiving mux and the sensing electrodes RX0, RX1, RX2, and RX3 are connected to each other.

Then, driving signals are transmitted to the driving electrodes TX0, TX1, TX2, and TX3, and sensing signals are received through the sensing electrodes RX0, RX1, RX2, and RX3 (step S102).

Subsequently, it is checked whether the pen frequency component is detected by fast Fourier transforming the sensing signals (step S104). The pen frequency component includes pen X-axis position information (eg, fifth frequency component f4) and pen pressure information (eg, sixth frequency component f5).

If it is checked that the pen frequency components f4 and f5 are detected in step S104, the pen X-axis position information (for example, the fifth frequency component f4) is stored and the pen pressure information of the pen (for example, the first frequency component f4) is stored. 6 The frequency component f5) is stored (step S106).

Then, the mux is set to 1 (step S108). That is, the second transmission input terminal 1 of the transmission mux provided in the transmission mux part 1224 and the driving electrodes TX0, TX1, TX2, TX3 are connected to each other, and provided in the reception mux part 1242 The second receiving input terminal 1 of the receiving mux and the sensing electrodes RX0, RX1, RX2, and RX3 are connected to each other.

Subsequently, the sensing signals received through the sensing electrodes RX0, RX1, RX2, and RX3 are fast Fourier transformed to check whether the pen frequency components f4 and f5 are detected (step S110).

When it is checked that the pen frequency components f4 and f5 are detected in step S110, the pen Y-axis position information f4 is stored, and pen pressure information f5 of the pen is stored (step S112).

Subsequently, pen coordinates (X, Y) and pen pressure information are reported (step S114). The pen coordinates (X, Y) are the pen X-axis position information f4 stored in step S106 and the pen Y-axis position information f4 stored in step S112. The pen pressure information f5 may be the pen pressure information f5 stored in step S106 or the pen pressure information f5 stored in step S112.

Subsequently, after the mux is set to 0 (step S116), the feedback is fed back to step S104. That is, the first transmission input terminal 0 of the transmission mux provided in the transmission mux part 1224 and the driving electrodes TX0, TX1, TX2, TX3 are connected to each other, and provided in the reception mux part 1242 The first receiving input terminal 0 of the receiving mux and the sensing electrodes RX0, RX1, RX2, and RX3 are connected to each other and fed back to step S104.

On the other hand, if it is checked that the pen frequency components f4 and f5 are not detected in step S104, it is checked whether the transmission frequency components f0 to f3 are detected by RX sensing (FFT processing) (step S120).

If it is checked that the transmission frequency components (f0 to f3) are not detected in step S120, the feedback is fed back to step S102, and if it is checked that the transmission frequency components (f0 to f3) are detected in step S120, the touch coordinates of the finger are stored (122 ), the stored finger coordinates are reported (step S124).

13 is a flowchart illustrating a method of recognizing touch coordinates in which a finger and a stylus pen are simultaneously recognized in the touch sensing device illustrated in FIGS. 11A and 11B.

11A, 11B, and 13, the mux is set to 0 (step S200). That is, the first transmission input terminal 0 of the transmission mux provided in the transmission mux part 1224 and the driving electrodes TX0, TX1, TX2, TX3 are connected to each other, and provided in the reception mux part 1242 The first receiving input terminal 0 of the receiving mux and the sensing electrodes RX0, RX1, RX2, and RX3 are connected to each other.

Then, driving signals are transmitted to the driving electrodes TX0, TX1, TX2, and TX3, and sensing signals are received through the sensing electrodes RX0, RX1, RX2, and RX3 (step S202).

Then, it is checked whether the pen frequency components (f0 to f5) are detected by fast Fourier transforming the sensing signals (step S204).

If it is checked that the pen frequency components f0 to f5 are not detected in step S204, the feedback is fed back to step S202.

If it is checked that the pen frequency components f0 to f5 are detected in step S204, the pen X-axis position information f4 is stored and pen pressure information f5 of the pen is stored (step S206).

Then, the mux is set to 1 (step S208). That is, the second transmission input terminal 1 of the transmission mux provided in the transmission mux part 1224 and the driving electrodes TX0, TX1, TX2, TX3 are connected to each other, and provided in the reception mux part 1242 The second receiving input terminal 1 of the receiving mux and the sensing electrodes RX0, RX1, RX2, and RX3 are connected to each other.

Subsequently, the sensing signals received through the sensing electrodes RX0, RX1, RX2, and RX3 are fast Fourier transformed to check whether the pen frequency components f4 and f5 are detected (step S210).

When it is checked whether the pen frequency components f4 and f5 are detected in step S210, the pen Y-axis position information f4 is stored, and pen pressure information f5 of the pen is stored (step S212).

Subsequently, finger coordinates (X,Y) information, pen coordinates (X,Y) information, and pen pressure information are reported (step S214), and the feedback is fed back to step S200. The finger coordinates (X,Y) information are pen X-axis coordinates stored in step S206 and pen Y-axis coordinates stored in step S212. The pen pressure information may be pen pressure information f5 stored in step S206 or pen pressure information f5 stored in step S212.

Although the operations of the method(s) herein have been shown and described in a specific order, the operations of each method may be modified so that certain operations may be performed in reverse order or that certain operations may be performed at least partially simultaneously with other operations. May be. In another embodiment, the instructions or sub-actions of the individual actions may be in an intermittent and/or alternating manner.

In the foregoing specification, the invention has been described with reference to specific exemplary embodiments of the invention. However, it will be apparent that various changes and variations may be made without departing from the broader spirit and scope of the invention as set forth in the appended claims. Accordingly, the specification and drawings are to be regarded as illustrative rather than restrictive.

100: touch sensing device 120: touch sensing controller
122: touch driving unit 124: touch sensing unit
126: touch determination unit 128: touch control unit
1222: transmission signal generation unit 1224: transmission mux unit
1242: receiving mux unit 1244: receiving sensing unit
1246: analog-digital conversion unit 1248: high-speed Fourier conversion unit
200: stylus pen 202: conductive case
204: conductive tip 206: pressure sensor
208: frequency signal generator 210: mixer
250: buttons 252: button processing unit
260: pen control unit 206: pen pressure sensor
207: pen pressure processing unit 260: pen control unit
270: power management unit 272: battery
280: waveform generator 290: waveform driver
282: f4 signal generator 284: f5 signal generator
292: first amplification unit 294: second amplification unit
TX0, TX1, TX2, TX3: driving electrode RX0, RX1, RX2, RX3: sensing electrode

Claims (18)

A touch panel including a plurality of driving electrodes and a plurality of sensing electrodes;
A stylus pen providing a pen frequency signal set to sense a position of a stylus pen and a pressure of the stylus pen to the touch panel; And
A touch that outputs a plurality of driving signals having different frequency components to the touch panel, and determines at least one of a touch coordinate of a finger and a touch coordinate of the stylus pen based on a plurality of sensing signals received from the touch panel Including a sensing controller, the stylus pen,
A conductive tip contactable to the touch panel;
A pressure sensor configured to measure a pressure of the conductive tip applied to the touch panel and output a pen pressure signal;
A frequency signal generator that generates a pressure detection signal set based on the pen pressure signal to measure the pen pressure of the stylus pen, and generates a position detection signal set to detect the position of the stylus pen;
A mixer for mixing the position sensing signal and the pressure sensing signal to provide a mixing signal to the conductive tip; And
Including one or more buttons variable according to the user's operation to output a button signal,
Wherein the pressure sensing signal has a fixed frequency and an amplitude that varies according to the button. The touch system of claim 1, wherein the pen frequency signal is a mixture of a position detection signal set to sense a position of a stylus pen and a pressure detection signal set to sense a pressure of a stylus pen. The touch system of claim 2, wherein the position detection signal and the driving signal have different frequency components. The touch system of claim 2, wherein the pressure sensing signal and the driving signal have different frequency components. The method of claim 1, wherein the touch sensing controller,
A touch driver connected to the driving electrodes and outputting the driving signals to the driving electrodes;
A touch sensing unit connected to the sensing electrodes and receiving the sensing signals through the sensing electrodes; And
And a touch determination unit for determining a touch coordinate based on sensing signals received through the touch sensing unit. The method of claim 5, wherein the touch driver,
A transmission signal generator including a plurality of transmission signal generators generating different driving signals; And
A plurality of transmission muxes having a first transmission input terminal connected to the transmission signal generator, a second transmission input terminal connected to the touch sensing unit, and a transmission output terminal connected to the driving electrode, and in response to a mux control signal provided from the outside, the A touch system comprising: a transmission mux unit to which a first transmission input terminal and the transmission output terminal are connected or the second transmission input terminal and the transmission output terminal are connected to each other. The method of claim 6, wherein the touch sensing unit,
A plurality of receiving muxes having a receiving output terminal, a first receiving input terminal connected to the sensing electrode, and a second receiving input terminal connected to a second transmitting input terminal of the transmitting mux part of the touch driver, and the first receiving mux in response to the mux control signal A reception mux unit in which a reception input terminal is connected to the reception output terminal or the second reception input terminal is connected to the reception output terminal;
A receiving sensing unit including a plurality of receiving sensing devices connected to a receiving output terminal of the receiving mux;
An analog-to-digital converter for digitally converting the sensing signals received through the reception sensors; And
And a fast Fourier transform unit for Fourier transforming the sensing signal digitally converted by the analog-to-digital converter. The method of claim 7, wherein in response to the mux control signal, a first input terminal of the transmitting mux and the driving electrode are connected to each other, and a first input terminal of the receiving mux and the receiving sensing unit are connected to each other,
A touch system comprising sensing the touch coordinates of the finger, the first axis coordinates of the stylus pen, and pen pressure information of the stylus pen. The method of claim 7, wherein in response to the mux control signal, a second input terminal of the transmitting mux and the driving electrode are connected to each other, and a second input terminal of the receiving mux and the receiving sensing unit are connected to each other,
A touch system, wherein the second axis coordinate of the stylus pen and pen pressure information of the stylus pen are sensed. The touch system of claim 1, wherein the driving signal is simultaneously output to the touch panel. A conductive tip, a pressure sensor that measures the pressure of the conductive tip and outputs a pen pressure signal, and a pressure sensing signal set based on the pen pressure signal to measure the pen pressure of the stylus pen, and a position set to detect the position of the stylus pen A frequency signal generator for generating a detection signal, a mixer for mixing the position detection signal and the pressure detection signal to provide a mixing signal to the conductive tip, and at least one button that is variable according to a user's operation and outputs a button signal. A touch driver connected to the driving electrodes of the touch panel in contact with the included stylus pen and outputting driving signals to the driving electrodes;
A touch sensing unit connected to sensing electrodes of the touch panel and receiving sensing signals through the sensing electrodes; And
A touch determination unit for determining at least one of a touch coordinate of a finger and a touch coordinate of the stylus pen based on the sensing signals,
Wherein the pressure sensing signal has a fixed frequency and an amplitude that varies according to the button. The method of claim 11, wherein the touch driver,
A transmission signal generator including a plurality of transmission signal generators for generating driving signals having different frequency components; And
A plurality of transmission muxes having a first transmission input terminal connected to the transmission signal generator, a second transmission input terminal connected to the touch sensing unit, and a transmission output terminal connected to the driving electrode, and in response to a mux control signal provided from the outside, the A touch sensing controller comprising a transmission mux unit connected to a first transmission input terminal and a transmission output terminal or connected to the second transmission input terminal and the transmission output terminal. The method of claim 12, wherein the touch sensing unit,
A plurality of receiving muxes having a receiving output terminal, a first receiving input terminal connected to the sensing electrode, and a second receiving input terminal connected to a second transmitting input terminal of the transmitting mux part of the touch driver, and the first receiving mux in response to the mux control signal A reception mux unit in which a reception input terminal is connected to the reception output terminal or the second reception input terminal is connected to the reception output terminal;
A receiving sensing unit including a plurality of receiving sensing devices connected to a receiving output terminal of the receiving mux;
An analog-to-digital converter for digitally converting the sensing signals received through the reception sensors; And
And a fast Fourier transform unit configured to Fourier transform the sensing signal digitally converted by the analog-to-digital converter. The method of claim 13, wherein in response to the mux control signal, a first input terminal of the transmitting mux and the driving electrode are connected to each other, and a first input terminal of the receiving mux and the receiving sensing unit are connected to each other,
A touch sensing controller, wherein the finger touch coordinates, the first axis coordinates of the stylus pen, and pen pressure information of the stylus pen are sensed. The method of claim 13, wherein in response to the mux control signal, a second input terminal of the transmitting mux and the driving electrode are connected to each other, and a second input terminal of the receiving mux and the receiving sensing unit are connected to each other,
The touch sensing controller, characterized in that the second axis coordinate of the stylus pen and pen pressure information of the stylus pen are sensed. A conductive tip contactable to the touch panel;
A pressure sensor configured to measure a pressure of the conductive tip applied to the touch panel and output a pen pressure signal;
A frequency signal generator configured to generate a pressure detection signal set based on the pen pressure signal to measure the pen pressure of the stylus pen, and generate a position detection signal set to detect the position of the stylus pen;
A mixer for mixing the position sensing signal and the pressure sensing signal to provide a mixing signal to the conductive tip; And
Including one or more buttons variable according to the user's operation to output a button signal,
The pressure detection signal is a stylus pen, characterized in that having a fixed frequency and an amplitude that varies according to the button. delete 17. The stylus pen of claim 16, wherein a frequency of each of the pressure sensing signal and the position sensing signal is different from a frequency of a driving signal applied to a driving electrode of the touch panel.

Images