KR102011581B1 - Radio frequency band based touch sensing apparatus and operation method of said apparatus - Google Patents

Abstract

One aspect of the present invention includes a touch sensing device. The apparatus includes at least one of a transmission line (TL) through which an AC signal is energized and at least one of a magnitude and a phase of the AC signal due to a dielectric constant of the touch means as the at least one transmission line is touched by a touch means. And a touch detector for detecting one change and detecting a touch position based on the detected change.

Description

High frequency band propagation-based touch sensing device and driving method of the device {RADIO FREQUENCY BAND BASED TOUCH SENSING APPARATUS AND OPERATION METHOD OF SAID APPARATUS}

The present invention relates to a touch sensing method, and more particularly, to a method for enabling high-precision touch sensing with a simple sensor structure.

Current touch sensor technology uses a resistor or capacitor generated between the finger and the touch sensor based on direct current (DC) frequency.

1A and 1B are conceptual views illustrating a general capacitive-based touch sensing method.

Referring to FIGS. 1A and 1B, P-cap touch sensing method is the most common touch sensing method. This is a technique for detecting a touch by using a change in capacitance between a finger and a metal plate, using a method of using self-capacitance (see FIG. 1A) and a method of using mutual capacitance (see FIG. 1A). 1b).

The capacitive touch sensing method is not suitable for the recent trend of requiring the thinnest possible thickness.

Looking at the recent trend of the touch panel system technology, the thickness of the display panel is getting thinner, the situation that requires extreme touch sensitivity, such as fingerprint recognition (biological information). Thus, the conventional capacitive touch sensing method is theoretically and fairly close to the limit to achieve precise touch sensitivity.

2 is a conceptual diagram illustrating capacitance changed according to a touch of a finger in a capacitive touch sensing method.

Referring to FIG. 2, the capacitance value is changed according to the touch of a finger. In this case, the thinner the display panel, the smaller the Signal to Noise Ratio (SNR), thus affecting the sensitivity of touch sensing. . As a result, there is a fundamental limitation in dealing with a gradually thinner touch screen, and the recent deterioration in the sensitivity of a touch sensor for a smartphone may be considered to indicate this problem.

Indeed, many of the current display panels are thinner than the prior art, but have more deteriorated touch sensitivity. In order to overcome this, the evolution of semiconductor thin film process with nanometer process precision is required, and it is difficult to equip the facility because the industry investment cost for this is estimated in trillion won.

In addition, there is a problem in that each layer and structure are complicated for sophisticated touch sensing, and even if overcomed, a capacitive-based sensing structure is disadvantageous for a flexible display. do.

An object according to an aspect of the present invention for solving the above problems is a transmission component and reflection according to a change in permittivity according to a touch using a transmission line (TL) of a radio frequency (RF) frequency band. The present invention provides a touch sensing method and apparatus for extracting accurate coordinates of a touch based on a change in magnitude and phase of a signal of a component.

According to an aspect of the present invention, there is provided a touch sensing apparatus, in which at least one transmission line (TL) and at least one transmission line through which an AC signal is energized are touched by a touch means. The touch detector may include a touch detector that detects a change in at least one of a magnitude and a phase of the AC signal due to the permittivity of the touch unit and detects a touch position based on the detected change.

The touch detector determines whether there is a touch based on a change in the magnitude of the alternating current signal detected as the at least one transmission line is touched and based on a phase change of the alternating current signal as the at least one transmission line is touched. Can detect the touch position.

The touch sensing apparatus may detect y-axis coordinates based on a change in magnitude of the AC signal, and detect x-axis coordinates based on a change in phase of the AC signal.

A plurality of the at least one transmission line may be arranged in parallel, and at least one port for providing and receiving a signal may be disposed at at least one of both ends of one transmission line.

The touch detector may include a first port of a first end of a first transmission line in which a touch is sensed among the at least one transmission line, and a second port of a first end of a second transmission line parallel to the first transmission line. The touch position may be calculated based on a parallel correlation and a cross correlation between the first port and a third port of a second end facing the first end of the second transmission line. .

The at least one port may be connected only to a first end of the at least one transmission line, and a matched load may be connected to an opposite second end of the first end so that reflection of the port does not occur.

The at least one transmission line may be formed to have different impedances according to positions.

The touch detector may detect a touch position by using a magnitude change of the AC signal sensed as a characteristic impedance is changed by a touch by the touch means in a transmission line having an impedance different according to the position.

The AC signal may be an AC signal in a band of 0.6 GHz to 0.8 GHz.

The AC signal may include a plurality of signals having different frequencies, and the signals having the plurality of different frequencies may be applied to generate a plurality of points at which phases of the AC signals overlap by touch by the touch means. have.

In accordance with an aspect of the present invention, there is provided a touch sensing method, comprising: driving an AC signal through at least one transmission line (TL) and touching the at least one transmission line by a touch means And detecting a change in at least one of a magnitude and a phase of the AC signal due to the permittivity of the touch means, and detecting a touch position based on the detected change.

According to the touch sensing method and apparatus of the present invention, it is possible to implement without requiring nanometer-level process precision for the touch sensor in order to maximize the touch sensitivity, and as a result, it is possible to drastically reduce the cost of producing future touch displays. have.

In addition, it is possible to implement touch sensitivity of equivalent performance with at least half of the number of touch sensors compared to the conventional capacitive / resistive touch sensor, and the effect of enabling ultra-precision touch technology such as fingerprint recognition and blood flow sensor with a much simpler sensor structure There is.

1A and 1B are conceptual views illustrating a general capacitive-based touch sensing method;
2 is a conceptual diagram illustrating capacitance changed according to a touch of a finger in a capacitive touch sensing method;
3 is a conceptual diagram illustrating a RF frequency propagation based touch sensing method according to an embodiment of the present invention;
4 is a view showing an RF frequency propagation based touch sensing apparatus according to an embodiment of the present invention;
5 is a conceptual diagram illustrating a process of detecting x-axis and y-axis coordinates through phase and magnitude changes in one transmission line;
6 is a conceptual diagram illustrating a process of detecting a touch sensing part in terms of impedance;
7 is a conceptual diagram illustrating a method of detecting a touch position in consideration of parallel and cross correlations according to another embodiment of the present invention;
8 is a diagram illustrating a touch sensing device including a plurality of transmission lines configured as one port according to another embodiment of the present invention;
9A and 9B are conceptual views illustrating a method of detecting a touch position through multi-frequency analysis according to another embodiment of the present invention;
10A and 10B are conceptual views illustrating a method of detecting a touch position using a transmission line whose thickness varies according to a position according to another embodiment of the present invention.

As the present invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description.

However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. In the following description of the present invention, the same reference numerals are used for the same elements in the drawings and redundant descriptions of the same elements will be omitted.

Throughout this specification, the touch sensing device may be implemented as a touch sensor, a touch screen panel, a fingerprint recognition device, or the like.

The term RF refers to a radio frequency, but in an embodiment of the present invention, refers to an AC signal, that is, a frequency of an AC electric signal, and the radio frequency is not limited to a specific frequency in a narrow range.

3 is a conceptual diagram illustrating an RF frequency propagation based touch sensing method according to an embodiment of the present invention.

Referring to FIG. 3, a touch sensing device (eg, a touch sensor, a touch screen panel, etc.) according to an embodiment of the present invention may include a transmission line (TL) through which an AC electrical signal is supplied and an alternating current in the transmission line. It can be configured to include a power source that provides a signal.

Before the touch, if a high-frequency alternating current signal is provided from the power source V, current flows at a constant dielectric constant epsilon _b and γ.

When a touch occurs, the dielectric constant changes in a predetermined region adjacent to the touched portion according to the dielectric constant of the finger (ε _f ), and the distance associated therewith may be defined as df. Accordingly, the permittivity according to the position of the transmission line is the original permittivity (ε _b ) from the left side to the x distance, the changed permittivity (ε _f ) in a certain section d _f where a finger touch occurs, and the right part of the section where the touch occurs At (lxd _f ), the original permittivity ε _b can be maintained.

The device calculates the coordinates of the touch of the user based on the magnitude and phase difference of the s-parameter S ₁₁ of the supplied AC signal according to the dielectric constant of the finger. Here, the s-parameter is a characteristic value related to RF / Microwave, and S ₁₁ is a characteristic value (reflection coefficient) indicating how much the voltage input from port 1 is transmitted to port 1. In other words, the number after is input and the number at the front means output port. That is, the voltage / power distribution between each port can be confirmed through this. The s-parameter is used as a parameter seen in the frequency domain.

According to the RF signal-based touch sensing method according to an embodiment of the present invention, since the touch position of the user is precisely detected based on a simple structure (signal-dielectric layer-ground), an advantage of having a thin thickness limit is provided. It has the advantage of simple process. In addition, the size of the device can be reduced by sensing with fewer ports.

4 is a diagram illustrating an RF frequency propagation-based touch sensing device according to an embodiment of the present invention. As shown in FIG. 4, the touch sensing apparatus according to the exemplary embodiment of the present invention may include a transmission line 410, a port 420, a driver 430, and a receiver 440.

Referring to FIG. 4, the transmission line 410 is a line through which an AC signal provided from the driving unit 430 is supplied. The transmission line 410 is a strip line and / or a microstrip line. It may include. However, the present invention is not necessarily limited to the above examples, and other lines capable of conducting electricity with permittivity may also be utilized.

The microstrip line is a twist of the coaxial cable used for high frequency transmission to distort the center conductor. The upper conductor represents a narrow transmission line, and the lower conductor represents ground (GND). The characteristic impedance of the transmission line may be determined by the relative dielectric constant of the substrate, the thickness, the thickness of the conductor, and the width thereof. The circuit can be miniaturized by using a substrate having a high dielectric constant. By way of example, the following materials may be used as the substrate material (the relative dielectric constant represents a general value).

Glass epoxy substrate: relative dielectric constant ε _r = 4.8 (UHF band ~ SHF band)

-Teflon substrate: relative dielectric constant ε _r = 2.6

Ceramic substrate: relative dielectric constant ε _r = 10.0

The transmission line 410 may exist as a single, and in some cases, a plurality of transmission lines 410 may exist in parallel.

The port 420 is connected to at least one end of the transmission line 410 to provide an input AC signal, and receives an output AC signal changed according to a change in dielectric constant. The ports 420 may be disposed at both ends of the transmission line 420, respectively. According to another exemplary embodiment of the present invention, one end of the transmission line 420 may be provided with a port 420 only by attaching a load to one end of the transmission line 420.

The driver 430 may include a driving circuit 432 and a touch detector 434. The driving circuit 432 generates an AC electrical signal and provides it to the port 420. The driving circuit 432 may sequentially supply an AC signal from the transmission line 410 above. The driving circuit 432 may be provided to the port 420 by adjusting the voltage, frequency and other parameters, including the voltage control means. According to an embodiment of the present invention, the frequency of the provided AC current is preferably 0.6 GHz to 0.8 GHz, and more preferably, the frequency of the 0.8 GHz band clearly shows the phase change and the magnitude change of the S-parameter for each position. have.

The touch detector 434 analyzes the size and / or phase change of the S-parameter based on an AC signal provided through the driving circuit 432 and an AC signal received through the port 420, and thus any port 420. It is possible to detect at which position there was a touch. The touch detector 434 is connected to the receiver 440 to receive a received signal received from ports connected to the receiver 440 (ports 420 connected to the right end of the transmission line 410 in FIG. 4). This can be used for touch location analysis.

The receiver 440 is electrically connected to the port 420 connected to one side of the transmission line 410 to receive a reception signal exiting from the port 420. If the port 420 is not present at both ends of the transmission line 410, that is, only one port 420 is present and there is a load at the opposite end part, the receiver 440 is independently. It may not necessarily be provided.

5 is a conceptual diagram illustrating a process of detecting x-axis and y-axis coordinates through phase and magnitude changes in one transmission line.

Referring to FIG. 5, one transmission line may be divided into a plurality of sections A1, A2,..., A10 in the x-axis direction, and a touch position may be detected for each section. The touch position detection in the x-axis direction may be performed by measuring the phase change of each transmission line.

In addition, in the structure in which a plurality of transmission lines are arranged in parallel, the touch position detection in the y-axis direction may be confirmed by analyzing the magnitude of a signal at a port (for example, port 1) connected to each transmission line.

According to an embodiment of the present invention, the position on the x-axis in the high frequency band may be extracted based on the phase change of the S-parameter. In addition, the position of the y-axis can be confirmed based on the change in the size of the S-parameter. This can be done by determining whether there is a touch, and when a touch occurs in a specific port, the transmission line in which the corresponding port exists is identified. Naturally, the y-axis position can be determined.

As described above, in the case of the signal size, it is only necessary to reveal the relationship between the connection line and the transmission line. Therefore, it is preferable that the AC signal uses a frequency having a large signal difference. However, in the case of the phase, since the continuous position is identified through the magnitude, an algorithm for positioning is required. In this case, it may be preferable to use a frequency band around 0.6 GHz to 0.8 GHz, which is a relatively low frequency, so that the phase difference does not consider a plurality of points. Accordingly, it is desirable to consider not only the transmission line but also the circuit phase difference.

6 is a conceptual diagram illustrating a process of detecting a touch sensing part in terms of impedance.

Referring to FIG. 6, the algorithm for detecting the phase difference described above may be calculated assuming that the transmission line portion and the finger touch capacitor portion are independent. In other words, the s-parameter calculated by considering the impedance part according to the resistivity of the transmission line and the s-parameter calculated by considering the capacitor part according to the finger touch independently and the sum of both s-parameters is determined according to the dielectric constant according to the touch. It can be considered as a change.

First, when calculating the s-parameter according to the transmission line, it can be considered that the dielectric constant of the transmission line is changed by the dielectric constant of the finger while ignoring the capacitor according to the finger touch. The distance from the left side of the transmission line to the portion 610 where the finger touch starts is l, the thickness 620 of the finger is d, the length of the total transmission line is tl, and the area 620 where the dielectric constant of the finger is applied. It can be assumed that the impedance of Z ₁ and the impedances 610 and 630 of the other portions are Z ₀ . The dielectric constant of the finger may be β ₁ , and the dielectric constant of the material constituting the transmission line may be β ₂ .

In this case, the entire ABCD matrix may be simply determined as a product of each ABCD matrix. Here, V ₁ , I ₁ , V ₂ , I ₂ , V ₃ , and I ₃ representing the voltage and current associated with each impedance may be expressed as follows.

And, A, B, C and D constituting each impedance can be expressed as follows.

In addition, the algorithm for calculating S ₁₁ can be represented by the following equation.

The impedance may be determined together with the permittivity when the thickness and width of the microstrip line are determined.

In this manner, after calculating the s-parameters in the transmission line, the device can calculate the finger touch capacitance value independently.

The device can calculate the ABCD matrix by considering only the finger touch capacitance value while ignoring the characteristic impedance value. Since we only have capacitors, we can calculate the entire ABCD matrix by calculating the ABCD matrix with only the admittance and multiplying by the ABCD matrix on both sides.

In this case, the S ₁₁ value of each model may be derived from the ABCD matrix as follows.

As such, since it is assumed that the s-parameter value of the transmission line and the s-parameter value according to the finger touch capacitance are considered independently, it can be expressed as follows by converting each of the S ₁₁ parameters.

7 is a conceptual diagram illustrating a method of detecting a touch position in consideration of parallel and cross correlations according to another embodiment of the present invention.

Referring to FIG. 7, when a touch occurs at a specific position of one transmission line, the touch of the touch at the port 712 that is calculated as a reflection coefficient among the ports 712 and 714 connected to the transmission line 710 where the touch occurs. It can detect the presence or absence, and detect the phase change to detect the x-axis coordinate of the touch. In this case, when there are a plurality of transmission lines, there may be an indirect permittivity change, not a direct change of permittivity, in another transmission line 712 parallel to the transmission line 710 in which the touch is generated. Thus, there may be a correlation of each port.

At this time, the most influential port is the correlation between the port 724 and the cross relationship with the port 722 in a position parallel to the specific port (for example, the port 712) of the transmission line 710 to be. That is, a more precise touch position can be detected in consideration of the correlation with the port 722 in the parallel position and the correlation with the cross port 724.

This correlation does not necessarily exist between only two transmission lines 710 and 712. Therefore, the correlation between the transmission line where the touch occurs and the transmission line that is separated by more than two intervals is also considered. In addition, the touch position may be detected more accurately in consideration of the interrelationship between three or more transmission lines.

However, in contrast to the S11 change for one transmission line, the difference in the magnitude of the signals of the ports in the parallel relationship and the cross relationship may be about -30 dB. However, the phase change of the ports in the parallel relationship and the cross relationship other than the transmission line may not be relatively large. Accordingly, the touch position may be detected by applying an algorithm that increases the influence on the magnitude change and relatively decreases the influence on the phase change, and in some cases, the influence on the phase change may be ignored.

8 is a diagram illustrating a touch sensing device including a plurality of transmission lines configured as one port according to another embodiment of the present invention.

Referring to FIG. 8, the device may basically measure the phase change and the magnitude change of an AC signal provided by connecting two ports, one at each end of one transmission line. In this case, the signal provided from the first port to the second port of one transmission line may be measured, or the signal provided from the second port to the first port may be measured. In addition, the signal reflected back from the first port via the second port and the signal reflected back from the second port through the first port may be measured.

According to another embodiment of the present invention, a configuration in which one port is reduced by further reducing the number of ports may be considered. In other words, the use of a single port can reduce the number of components entering the device in half.

Ports that have been removed from the port can be used in the same way as the two-port connection method because the port reflection does not occur when a load matched to the microstrip line is applied.

In more detail, when the impedance of the touch portion of the transmission line is set to Z1 and the remaining portion to ZO, and the model is implemented through the ABCD matrix (see FIG. 6), the characteristic impedances of a4 and b4 and S ₁₁ can be calculated assuming that the same impedance is applied. In other words, it is assumed that impedance matching is made. The part connecting the right port actually acts only as an impedance when calculating S ₁₁ . Therefore, by connecting 1 port on the left side instead of 2 ports and only matching loads on the right side, a transmission line like the algorithm according to the above equation can be implemented.

9A and 9B are conceptual views illustrating a method of detecting a touch position through multi-frequency analysis according to another embodiment of the present invention.

Referring to FIG. 9A, when using a high frequency, the device according to the embodiment of the present invention has a higher resolution because a plurality of points where phases overlap and a phase difference according to distance increases. Thus, the 0.6 GHz to 0.8 GHz band may be desirable. In this case, the position may be determined by using a plurality of high frequencies to distinguish a plurality of points overlapping in a specific phase. In other words, the driving circuit preferably provides an AC signal having a plurality of different frequencies.

Referring to FIG. 9B, when the total length l of the transmission line is 2λ, where λ represents a wavelength of an AC signal having a specific frequency, a plurality of solutions exist at a specific position according to the following equation. do.

In addition, if the total length l of the transmission line is 3λ, the positions which have been plurally existing have different phases according to the following equation.

This allows you to use multiple high frequencies without problems. This can increase the resolution of the touch sensing by increasing the phase difference according to the distance.

10A and 10B are conceptual views illustrating a method of detecting a touch position using a transmission line whose thickness varies according to a position according to another embodiment of the present invention.

Referring to FIG. 10A, a method of detecting a touch position by a phase requires a process of analyzing a change in phase, and thus an operation may be delayed. Therefore, the touch line may be sensed using only the size information by deforming the transmission line to gradually increase the thickness without considering the phase information.

By deforming the microstrip line to gradually thicken, the characteristic impedance gradually decreases. In this case, since most of the reflection is performed by the fingertip, the characteristic impedance according to the position is different so that the touch position can be detected only by the magnitude information of the AC signal. In this case, since the size is not used to find the horizontal position and no phase data is used, the processing speed is increased.

Referring to FIG. 10B, the transmission line has a different thickness and / or width depending on the position, so that the characteristic impedance is gradually changed. At this time, the characteristic impedance of the finger has a completely different dielectric constant value far from the gradual difference value, and thus the characteristic impedance also has many differences from the gradual difference value. It may be larger or smaller. While the characteristic impedance is gradually changed, the point where the difference in impedance suddenly changes can be seen as the point where the finger touches, and the position on the x-axis can be determined based on the distance to it.

This is as follows.

Also. Based on the impedance value of Z _O above, the change of the s-parameter according to the transmission line by the finger and the change of the s-parameter according to the finger touch capacitance are calculated and summed independently, which is calculated based on the following equation Can be.

The device can calculate the touch position using only the magnitude value of the AC signal using the algorithm related to the characteristic impedance as described above.

Although described above with reference to the drawings and embodiments, it does not mean that the scope of protection of the present invention is limited by the above drawings or embodiments, and those skilled in the art to the spirit of the present invention described in the claims It will be understood that various modifications and variations can be made in the present invention without departing from the scope of the invention.

Claims (11)

At least one transmission line (TL) through which an AC signal is supplied; And
As the at least one transmission line is touched by the touch means, the touch detector detects a change in at least one of the magnitude and phase of the AC signal caused by the dielectric constant of the touch means and detects a touch position based on the detected change. Including, but the touch detector is
Determining whether there is a touch based on a change in the magnitude of the AC signal sensed as the at least one transmission line is touched;
And a touch position detection unit based on a phase change of the AC signal sensed as the at least one transmission line is touched. delete The method of claim 2,
Detecting y-axis coordinates based on a change in magnitude of the AC signal;
And a touch sensing device to detect x-axis coordinates based on a phase change of the AC signal. At least one transmission line (TL) through which an AC signal is supplied; And
As the at least one transmission line is touched by the touch means, the touch detector detects a change in at least one of the magnitude and phase of the AC signal caused by the dielectric constant of the touch means and detects a touch position based on the detected change. Including,
The plurality of at least one transmission line is arranged in parallel,
And at least one port for providing and receiving signals at at least one of both ends of one transmission line. The method of claim 4, wherein the touch detector is
Parallel between a first port of a first end of a first transmission line where a touch is sensed among the at least one transmission line and a second port of a first end of a second transmission line parallel to the first transmission line. Interrelationship; And
And a touch position is calculated based on a cross correlation between the first port and a third port of a second end facing the first end of the second transmission line. The method of claim 4, wherein
The at least one port is connected only to a first end of the at least one transmission line,
And a matched load is connected to an opposing second end of the first end such that a matching load is not generated. At least one transmission line (TL) through which an AC signal is supplied; And
As the at least one transmission line is touched by the touch means, the touch detector detects a change in at least one of the magnitude and phase of the AC signal caused by the dielectric constant of the touch means and detects a touch position based on the detected change. Including,
The at least one transmission line is formed to have a different impedance according to the position. The method of claim 7, wherein
And the touch detector detects a touch position by using a magnitude change of the AC signal sensed as a characteristic impedance is changed by a touch by the touch means in a transmission line having an impedance different according to the position. At least one transmission line (TL) through which an AC signal is supplied; And
As the at least one transmission line is touched by the touch means, the touch detector detects a change in at least one of the magnitude and phase of the AC signal caused by the dielectric constant of the touch means and detects a touch position based on the detected change. Including,
And the AC signal is an AC signal in a band of 0.6 GHz to 0.8 GHz. At least one transmission line (TL) through which an AC signal is supplied; And
As the at least one transmission line is touched by the touch means, the touch detector detects a change in at least one of the magnitude and phase of the AC signal caused by the dielectric constant of the touch means and detects a touch position based on the detected change. Including,
The AC signal includes a signal having a plurality of different frequencies,
And a plurality of points at which phases of the AC signal overlap by touch by the touch means by applying the signals having a plurality of different frequencies. Driving an AC signal through at least one transmission line (TL); And
Detecting a touch position based on the detected change by detecting a change in at least one of a magnitude and a phase of the AC signal caused by the dielectric constant of the touch means as the at least one transmission line is touched by the touch means Including, but detecting the touch position
Determining whether there is a touch based on a change in the magnitude of the AC signal sensed as the at least one transmission line is touched; And
And detecting a touch position based on a phase change of the AC signal sensed as the at least one transmission line is touched.

Images