KR102081809B1 - Capacitive touch system and driving method thereof - Google Patents

Abstract

Disclosed are a capacitive touch system with an increased peak-to-average power ratio (PAPR), and an operation method thereof. According to the present invention, the capacitive touch system comprises: a touch panel including a plurality of TX electrodes and RX electrodes; a TX operation unit providing TX signals with a different frequency to the TX electrodes, respectively; an RX reception unit receiving RX signals outputted from the RX electrodes, respectively; a frequency mixing unit mixing a mixing signal with a predetermined frequency to each of the TX or RX signals to output a mixed sensing signal; and a signal detection unit separating the mixing signal from the mixed sensing signal to reconfigure a raw touch signal. Accordingly, a sinusoidal signal with a predetermined frequency is mixed to the TX signal applied to a TX terminal or the RX signal outputted from an RX terminal, and deconvolution processing or production of the inverse of the mixing signal is performed to restore the raw touch signal such that generation of charge overflow is prevented without lowering a frame rate or a sound/noise ratio (SNR), thereby increasing the PAPR.

Description

Capacitive touch system and its driving method {CAPACITIVE TOUCH SYSTEM AND DRIVING METHOD THEREOF}

The present invention relates to a capacitive touch system and a driving method thereof, and more particularly, to a capacitive touch system and a driving method thereof having an improved peak-to-average power ratio (PAPR). It is about.

High frame rates and signal-to-noise ratios (SNRs) are essential for fast sensing of small capacitance changes. Accordingly, in order to secure high SNR and frame rate, a parallel driving method or a multiple frequency driving method for simultaneously driving all TX electrodes has been proposed.

The parallel driving method applies a TX signal in a specific matrix form to all TX electrodes, and senses capacitance change of the touch panel in the touch controller. Since the parallel driving method drives all TX electrodes at the same time, the sensing time is long, and the improvement of the SNR can be ensured. However, as the number of TX electrodes increases, the size of the matrix to be driven increases, which may cause a problem that the time for driving the matrix increases (that is, the frame rate decreases). In addition, when the TX signal of the same phase is driven to all TX electrodes according to the form of the matrix, a signal that exceeds the sensing range of the readout circuit in the analog front end (AFE) IC may be applied. This is called charge overflow. Therefore, in order to solve this problem, the TX electrode must be partially driven or the driving voltage can be lowered, thereby reducing the frame rate or the SNR.

Like the parallel driving method, the multi-frequency driving method is a driving method for securing high frame rate and SNR. Since external noise is first determined and a frequency of the TX signal required for driving is allocated to a region having a small noise, high SNR can be secured. In addition, it is possible to secure the frame rate by driving the TX signal to multiple TX electrodes at the same time.

However, when driving TX signals simultaneously to multiple TX electrodes, it can be seen that constructive and destructive interference occurs when each TX signal is observed from the signal receiver. In particular, when the constructive interference is maximized, a peak signal is generated in the TX signal. This peak signal exceeds the input dynamic range of the receiving circuit, causing a charge overflow that is a distortion of the received signal.

In addition, if the amplification ratio of the input signal is lowered to prevent charge overflow, the SNR drops sharply due to too small signal gain. As a result, the corresponding driving method partially drives the TX electrode or lowers the voltage of the TX signal, thereby reducing the frame rate and the SNR.

0001) Korea Patent Publication No. 10-2016-0085126 (2016. 07. 15.) (Electronic device and touch scan method of the electronic device) Korean Patent Registration No. 10-1863162 (2018. 05. 25.) (Technology for Locally Improving Signal-to-Noise in Capacitive Touch Sensors)

Therefore, the technical problem of the present invention has been made in view of the above, an object of the present invention, to provide a capacitive touch system implemented to suppress the occurrence of charge overflow without reducing the frame rate or SNR when driving the multi-frequency will be.

Another object of the present invention is to provide a method of driving the capacitive touch system.

According to one or more exemplary embodiments, a capacitive touch system includes a touch panel including a plurality of TX electrodes and a plurality of RX electrodes; A TX driver which provides TX signals having different frequencies to the TX electrodes, respectively; An RX receiver configured to receive RX signals output from each of the RX electrodes; A frequency mixing unit configured to mix a mixing signal having a specific frequency to each of the TX signals or the RX signals and output a mixed sensing signal; And a signal detector configured to reconstruct the touch original signal by separating the mixed signal from the mixed sensing signal.

In one embodiment, the frequency of the TX signals may have any one of equal intervals, fractional intervals and random intervals.

In one embodiment, the mixing signal may include a sine wave. Here, the frequency of the sinusoidal wave may be an integer multiple of 0.5 times the minimum frequency interval of the minimum frequency interval of the TX signals.

The signal detector may reconstruct the mixed signal by applying a band pass filter when the mixing frequency of the mixing signal is greater than the maximum frequency of the TX signal and the minimum frequency of the TX signal. The signal detector may include: an ADC block configured to ADC convert the mixed sensing signal; And an FFT block configured to detect the mixed signal by performing FFT processing on the mixed ADC sensed signal.

In one embodiment, the signal detector may apply a deconvolution filter to reconstruct the touch original signal from the FFT result. The signal detector may include: an ADC block configured to ADC convert the mixed sensing signal; An FFT block for FFT processing the ADC converted signal; And a deconvolution block that detects the mixed sensing signal by deconvolving the FFT processed signal.

In an example embodiment, the signal detector may reconstruct the mixed sensing signal by multiplying the mixed signal by the inverse of the mixed signal by multiplying the mixed signal in the time domain. The signal detector may include: an ADC block configured to ADC convert the mixed sensing signal; A first multiplication block multiplying the ADC-converted mixed sensing signal by the inverse of the mixing signal; And an FFT block configured to detect the mixed sensing signal by FFT processing the mixed sensing signal multiplied by the inverse of the mixing signal.

In order to achieve the above object of the present invention, a method of driving a capacitive touch system according to an embodiment includes mixing a mixed signal having a specific frequency with each of the TX signals having different frequencies and outputting the mixed signal to the TX electrode. step; And reconstructing the touch original signal by separating the mixed signal from each of the mixed sensing signals output through the RX electrode.

In one embodiment, the reconstructing the touch original signal may include: digitally converting each of the mixed sensing signals; And detecting the touch original signal by performing FFT on each of the digitally converted sensing signals.

In one embodiment, the reconstructing the touch original signal may include: digitally converting each of the mixed sensing signals; FFT processing each of the digitally converted sensing signals; And deconvoluting the mixed sensing signal processed by the FFT to detect the touch original signal.

In one embodiment, the reconstructing the touch original signal may include: digitally converting each of the mixed sensing signals; Multiplying each of the digitally converted sensing signals by the inverse of the mixing signal; And detecting the touch original signal by performing FFT processing on the signals multiplied by the reciprocal of the mixing signal.

According to another aspect of the present invention, there is provided a method of driving a capacitive touch system, including: outputting TX signals having different frequencies to a TX electrode; Mixing a mixed signal having a specific frequency with each of the RX signals output through the RX electrode and outputting a mixed sensing signal; And reconstructing the touch original signal by separating the mixed signal from each of the mixed sensing signals.

According to the capacitive touch system and a driving method thereof, a sinusoidal signal having a specific frequency is mixed with a TX signal applied to a TX terminal or an RX signal output from an RX terminal, and deconvolution processing is performed to restore the original touch signal. Alternatively, by multiplying the inverse of the mixed signal, charge overflow can be prevented from occurring without lowering the frame rate or lowering the SNR, thereby improving the peak-to-average power ratio (PAPR).

1 is a block diagram schematically illustrating a typical capacitive touch system.
2A to 2D are waveform diagrams of signals detected at the RX stage when TX signals of different frequencies are applied to each of the TX electrodes.
3A is a waveform diagram schematically illustrating a standardized input signal output through the RX stage when the frequency intervals between the TX signals are equal intervals, and FIG. 3B illustrates the RX stage when the frequency intervals between the TX signals are fractional intervals. This is a waveform diagram for schematically illustrating a standardized input signal output through the.
4 is a block diagram schematically illustrating a capacitive touch system according to an embodiment of the present invention.
5 is a block diagram schematically illustrating a capacitive touch system according to another exemplary embodiment of the present invention.
FIG. 6 is a waveform diagram schematically illustrating a result of frequency mixing with a mixing signal when frequency intervals of TX signals are equally spaced.
FIG. 7 is a waveform diagram schematically illustrating a result of frequency mixing with a mixing signal when a frequency interval of TX signals is a fractional interval.
FIG. 8 is a block diagram schematically illustrating a first embodiment of the signal detection unit illustrated in FIG. 4 or 5.
FIG. 9 is a conceptual diagram schematically illustrating reconstruction of a touch original signal according to the signal detector described in FIG. 8.
FIG. 10 is a block diagram schematically illustrating a second embodiment of the signal detection unit illustrated in FIG. 4 or 5.
FIG. 11 is a waveform diagram schematically illustrating a signal detection method by the signal detection unit described in FIG. 10.
FIG. 12 is a conceptual diagram schematically illustrating reconstruction of a touch original signal according to the signal detector described in FIG. 10.
FIG. 13 is a block diagram schematically illustrating a third embodiment of the signal detection unit illustrated in FIG. 4 or 5.
FIG. 14 is a waveform diagram schematically illustrating a signal detection method by the signal detection unit described in FIG. 13.
15 is a frequency spectrum for schematically illustrating an example of the RX signal output through the RX stage.
16 is a frequency spectrum for schematically illustrating another example of the RX signal output through the RX stage.
17 is a frequency spectrum for schematically illustrating an example of reconstructing a mixed signal by applying a filter when the mixing frequency of the mixed signal is greater than (maximum frequency of the TX signal-minimum frequency of the TX signal) / 2.
18 is a diagram illustrating an example of reconstructing a touch original signal by multiplying the sine wave by the inverse of the sine wave multiplied by mixing in the time domain.

Hereinafter, with reference to the accompanying drawings, it will be described in detail the present invention. As the inventive concept allows for various changes and numerous embodiments, particular 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 the specific form disclosed, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing the drawings, similar reference numerals are used for similar elements. In the accompanying drawings, the dimensions of the structures are shown in an enlarged scale than actual for clarity of the 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. 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, action, component, part, or combination thereof described on 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, parts, or combinations thereof.

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. 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.

1 is a block diagram schematically illustrating a typical capacitive touch system. In particular, a capacitive touch system is shown that is driven in a multi-frequency driving manner.

Referring to FIG. 1, a typical capacitive touch system includes a touch panel 10, a TX driver 20, an RX receiver 30, and a signal detector 40.

The TX driver 20 applies TX signals having different frequencies to each of the TX electrodes of the touch panel 10 so that the frequencies output to the TX electrodes do not overlap in order to identify the plurality of touch positions.

The signal output from each TX electrode is changed to the frequency axis through the FFT block, and the touch position is determined by checking each TX frequency on the frequency axis. However, as the number of TX electrodes increases, there is a problem of peak-to-average power ratio (PAPR). That is, since the TX electrodes are driven at the same time, the sine wave of each TX frequency is summed and output at the RX stage.

2A to 2D are waveform diagrams of signals detected at the RX stage when TX signals of different frequencies are applied to each of the TX electrodes.

Referring to FIG. 2A, when TX signals of three different frequencies are applied to each of the TX electrodes, it may be confirmed that three peaks are added to the RX signal detected at the RX terminal.

Referring to FIG. 2B, when TX signals of 10 different frequencies are applied to each of the TX electrodes, it may be confirmed that there are values added with 10 peaks in the RX signal detected at the RX terminal.

Referring to FIG. 2C, when TX signals of 30 different frequencies are applied to each of the TX electrodes, it may be confirmed that 30 peaks are added to the RX signal detected at the RX terminal.

Referring to FIG. 2D, when TX signals of 100 different frequencies are applied to each of the TX electrodes, it may be confirmed that 100 peaks are added to the RX signal detected at the RX terminal.

As such, characteristics of the RX signal output through the RX stage in the touch panel employing the multi-frequency driving method are as follows.

First, as the number of TX electrodes increases, the peak of the RX stage increases on the time axis, and the width of time at which the peak occurs decreases.

Second, even if the peak of the signal is large, (-1 to 1) is long in the section where the small signal exists.

FIG. 3A is a waveform diagram schematically illustrating a standardized input signal output through the RX stage when the frequency intervals between the TX signals are equal intervals, and FIG. 3B illustrates the RX stage when the frequency intervals between the TX signals are fractional intervals. This is a waveform diagram for schematically illustrating a standardized input signal output through the.

As shown in Figs. 3A and 3B, each of TX signals having different frequencies is simultaneously applied to the TX electrodes. Therefore, when the TX signals are simultaneously applied to and driven by the N TX electrodes (that is, the frequency may be equal intervals, decimal intervals, or random intervals), driving N electrodes generates N times the peak signal. In an ideal system. For convenience, the description will be based on an ideal touch screen system. In reality, although it becomes smaller than N by the frequency characteristic of the sensor of the touch screen, as the overall TX frequency increases, the peak value at which the signal increase occurs accordingly increases. The constant value C is multiplied according to the mutual capacitance between the TX electrode and the RX electrode, and the signal amplitude (s) is determined as N × C = n.

Quantitative analysis of the above is as follows.

Assume that n is the number of TX electrodes, f _l is the lowest frequency of the TX signal, and f _d is the interval between frequencies. At this time, if the sum of the TX signal having a frequency f _d of the same interval from the low frequency f _l signal amplitude (signal amplitude) is calculated as in Equation 1 below.

[Equation 1]

At this time, if the number of TX electrodes is 2 ^k , it is calculated as in Equation 2 below.

[Equation 2]

In the case of sin and cosine, since the maximum value is 1, the maximum value of the signal amplitude is determined to be 2 ^k .

In the present invention, when the capacitive touch system uses a multi-frequency driving method, a mixing signal having a specific frequency is mixed with a TX signal applied to a TX electrode or an RX signal output through an RX electrode, thereby lowering the frame rate. Disclosed is a method that can improve the maximum power-to-average power ratio (PAPR) by preventing charge overflow from occurring without lowering the SNR.

4 is a block diagram schematically illustrating a capacitive touch system according to an embodiment of the present invention. In particular, a block diagram of a capacitive touch system for schematically explaining a method of mixing a mixing signal having a specific frequency with a TX signal applied to a TX electrode to prevent charge overflow without a decrease in frame rate or SNR is shown. do.

Referring to FIG. 4, in the capacitive touch system according to the exemplary embodiment, the touch panel 110, the TX driver 120, the frequency mixer 130, the RX receiver 140, and the signal detector 150 may be used. It includes.

The touch panel 110 includes a plurality of TX electrodes that transmit TX signals and a plurality of RX electrodes that transmit RX signals. The TX electrodes and the RX electrodes may be disposed in different planes or in the same plane.

The TX driver 120 outputs TX signals having different frequencies.

The frequency mixing unit 130 mixes a mixing signal having a specific frequency with the TX signal output from the TX driver 120, and provides the mixed TX signal to the TX electrodes of the touch panel 110.

The RX receiver 140 receives an RX signal provided from the RX electrodes of the touch panel 110.

The signal detector 150 detects the mixed signal output from the frequency mixer 130.

In the present embodiment, the frequency of the TX signal may be equal intervals, fractional intervals, random intervals, and the like. The mixing frequency of the mixing signal may be 0.5 times the minimum frequency interval of the TX signal to an integer multiple of the minimum frequency interval. Here, when the frequencies of the plurality of TX signals are arranged in the order of magnitude of the frequencies, the smallest interval among the intervals of the sequentially arranged frequencies is defined as the minimum frequency interval.

In the above, it was described that the frequency mixing unit mixes the mixing signal with each of the TX signals output from the TX driver. The frequency mixing unit may configure the capacitive touch system to mix the mixing signal with each of the RX signals output from the touch panel.

5 is a block diagram schematically illustrating a capacitive touch system according to another exemplary embodiment of the present invention.

Referring to FIG. 5, in the capacitive touch system according to another exemplary embodiment, the touch panel 110, the TX driver 120, the frequency mixer 230, the RX receiver 140, and the signal detector 150 may be used. It includes.

The touch panel 110 includes a plurality of TX electrodes that transmit TX signals and a plurality of RX electrodes that transmit RX signals. The TX electrodes and the RX electrodes may be disposed in different planes or in the same plane.

The TX driver 120 outputs TX signals having different frequencies to the TX electrodes of the touch panel 110.

The frequency mixing unit 230 mixes a mixing signal having a specific frequency with the RX signal output from the touch panel 110, and provides the mixed RX signal to the RX receiving unit 140.

The RX receiver 140 receives an RX signal mixed with a mixed signal by the frequency mixer 230.

The signal detector 150 detects the mixed RX signal output from the RX receiver 140.

In this embodiment, the frequency intervals of TX signals having different frequencies may be equal intervals, fractional intervals, random intervals, or the like. The mixing frequency of the mixing signal may be 0.5 times the minimum frequency interval of the TX signal to an integer multiple of the minimum frequency interval.

FIG. 6 is a waveform diagram schematically illustrating a result of frequency mixing with a mixing signal when frequency intervals of TX signals are equally spaced.

Referring to FIG. 6, when the frequency intervals of the TX signals are equally spaced, when the sum of the TX signals and the mixing signal are added, the mixing result converges to a specific level DC.

FIG. 7 is a waveform diagram schematically illustrating a result of frequency mixing with a mixing signal when a frequency interval of TX signals is a fractional interval.

Referring to FIG. 7, when the frequency interval of the TX signals is a fractional interval, when the sum of the TX signals and the mixing signal are summed, the mixing result decreases the amplitude.

Next, a case where frequency mixing is used will be described below.

In the present invention, when mixing a mixed signal of a specific frequency to a signal input to the TX stage or a signal output through the RX stage through the frequency mixing unit (for example, mixing at a frequency that is 1/2 of the TX signal frequency interval) Signal amplitude is represented by Equation 3 below.

[Equation 3]

Since cosine is distributed between -1 and 1, the maximum signal amplitude at the time of frequency mixing converges to one.

FIG. 8 is a block diagram schematically illustrating a first embodiment of the signal detector 150 illustrated in FIG. 4 or 5. FIG. 9 is a conceptual diagram schematically illustrating reconstruction of a touch original signal by the signal detector 150 described with reference to FIG. 8. In particular, when the mixing frequency of the mixing signal is greater than (maximum frequency-minimum frequency of the TX signal) / 2, an example in which the band pass filter may be applied to reconstruct the mixing signal is shown.

8 and 9, the signal detection unit 150 according to the first embodiment includes an ADC block 510, an FFT block 512, and a signal detection block 514.

The ADC block 510 ADC converts a sensing signal mixed with a mixed signal having a specific frequency and provides the ADC converted mixed sensing signal to the FFT block 512.

The FFT block 512 performs an FFT process on the ADC-converted mixed sensing signal and provides it to the signal detection block 514.

The signal detection block 514 reconstructs the mixed signal from the mixed sensing signal FFT processed by the FFT block 512. Mixing frequency (f _mix) the <signal band (f _band) / 2> than large, the signal detection block 514 of the touch original signal of the mixed signal is composed of a band-pass filter can be reconfigured to touch the original signal .

As shown in Equation 4 below, a sensing signal s _mix in which a mixing signal having a specific frequency is mixed may be separated into a signal different from f _mix which is a mixing frequency of the mixing signal.

[Equation 4]

와

로 분리할 수 있기 때문에 두 부분은, 도 9에 도시된 바와 같이, 디지털 밴드패스필터(digital band-pass filter)로 분리할 수 있다. So, s _mix

Wow

The two parts can be separated by a digital band-pass filter, as shown in FIG. 9.

Meanwhile, a deconvolution method may be used to recover the original touch signal by using the sum of the TX signal frequency and the mixing frequency of the mixing signal. Here, deconvolution is an operation that removes convolution, and inversely removes the effect of convolution to know the input signal or system impulse response in the output signal resulting from the convolution of the input signal and the system impulse response. It is.

FIG. 10 is a block diagram schematically illustrating a second embodiment of the signal detector 150 illustrated in FIG. 4 or 5. FIG. 11 is a waveform diagram schematically illustrating a signal detection method according to the signal detector 150 described with reference to FIG. 10. FIG. 12 is a conceptual diagram schematically illustrating reconstruction of a touch original signal by the signal detector 150 described with reference to FIG. 10. In particular, a diagram illustrating an example of reconstructing a touch original signal from an FFT result by applying a deconvolution filter.

10 and 11, the signal detector 150 according to the second embodiment includes an ADC block 520, an FFT block 522, a deconvolution block 524, and a signal detection block 526. .

The ADC block 520 converts the mixed sensing signal into an ADC and provides the ADC converted mixed sensing signal to the FFT block 522.

The FFT block 522 provides the deconvolution block 524 after FFT processing for converting an ADC-converted mixed sensing signal into a frequency domain.

The deconvolution block 524 deconvolutions the FFT processed mixed sensing signal and provides the deconvolution block to the signal detection block 526.

Specifically, to detect the signal according to the present embodiment, the signal passing through the ADC block 520 inside the readout IC disposed in the analog front end (AFE) IC is deconballed in the discrete frequency domain. Apply the solution. The equation for this is shown in Equation 5 below.

[Equation 5]

If the lengths of F _mix and S are 3 and 5, respectively, the result of S _mix signal is as follows.

In this case, the mixing result is changed as shown in FIG. 11 according to f _mix .

상기한 신호를 디콘볼루션하는 경우 아래와 같은 의사코드(pseudo code)를 사용하여 수행한다. Meanwhile,

In the case of deconvolution of the signal, the following pseudo code is used.

To reduce computational load, short f _mix lengths are recommended. When the sample time for FFT processing and the period of the mixing frequency of the mixing signal are the same, the shortest length f _mix can be used.

The signal detection block 526 detects the touch original signal from the deconvolutiond signal.

FIG. 13 is a block diagram schematically illustrating a third embodiment of the signal detector 150 illustrated in FIG. 4 or 5. FIG. 14 is a waveform diagram schematically illustrating a signal detection method according to the signal detector 150 described with reference to FIG. 13. In particular, a diagram illustrating an example of reconstructing a touch original signal multiplied by an inverse sine wave by the size of a sine wave multiplied by mixing in the time domain.

Referring to FIG. 12, the signal detector 150 according to the third embodiment includes an ADC block 530, an inverse sine wave processing block 532, an FFT block 534, and a signal detection block 536.

The ADC block 530 ADC-converts the mixed sensing signal and provides the inverted sine wave processing block 532 to the ADC-mixed mixed sensing signal.

The inverse sinusoidal processing block 532 multiplies an inverse sinusoidal signal by the converted ADC signal by a sinusoidal signal multiplied as a mixing signal and provides a signal obtained by multiplying the inverse sinusoidal signal to the FFT block 534.

The FFT block 534 performs FFT processing on the signal multiplied by the inverse sinusoidal signal and provides the signal to the signal detection block 536.

The signal detection block 536 detects a touch original signal from the FFT processed signal.

The signal detection method according to the present embodiment is a method of reconstructing a touch original signal by multiplying by 1 / sine wave (ie, 1 / sin) by the amount of sinusoidal wave (ie, sin) multiplied by mixing in the time domain. .

When the touch original signal and the mixing signal are multiplied, a DC type mixing result is output. In this case, the original touch signal is recovered by multiplying the DC mixing result by 1 / (mixing signal). The waveform diagram for the above recovery method is shown in FIG.

Next, a description will be given of how the frequency domain result is obtained in the steps of detecting the mixed signal in various ways.

Hereinafter, assuming that seven TX channels exist in the touch panel and the fifth TX position is touched.

15 is a frequency spectrum for schematically illustrating an example of the RX signal output through the RX stage. In particular, it is shown separately when a mixed signal is not mixed and when a mixed signal having a fd / 2 frequency is mixed.

Referring to FIG. 15, when the mixed signal is not mixed, the frequency components f1, f2, f3, f4, f6, and f7 included in the RX signal output through the RX stage are detected with a uniform magnitude and included in the RX signal. The frequency component f5 is detected at a lower magnitude than the frequency components f1, f2, f3, f4, f6, and f7. Here, the interval between frequency components is fd.

On the other hand, when a mixed signal having a frequency of fd / 2 is mixed, the two signals are opposite and have the same magnitude between f1 and f2, between f2 and f3, between f3 and f4, and between f6 and f7. Offset each other. However, because the phases of the two signals are different from each other or different in magnitude between f4 and f5 and between f5 and f6, only a part of the two signals are canceled. Thus, when a mixed signal having a frequency fd / 2 is mixed, the final result is applied to the frequency components f1- (fd / 2), f4 + (fd / 2), f5 + (fd / 2) and f7 + (fd / 2). Only the corresponding signals remain. Here, the magnitudes of the f4 + (fd / 2) and f5 + (fd / 2) frequency components are smaller than the magnitudes of the f1- (fd / 2) and f7 + (fd / 2) frequency components.

Accordingly, it can be confirmed that the fifth TX electrode to which the TX signal of the f5 frequency, which is a value between the f4- (fd / 2) frequency component and the f5- (fd / 2) frequency component, is applied.

16 is a frequency spectrum for schematically illustrating another example of the RX signal output through the RX stage. In particular, it is shown separately when the mixing signal is not mixed and when the mixing signal having the fd frequency is mixed.

Referring to FIG. 16, when not mixed, the frequency components f1, f2, f3, f4, f6, and f7 included in the RX signal output through the RX stage are detected with a uniform magnitude, and the f5 frequency included in the RX signal. The component is detected at a low size. Here, the spacing between frequencies is fd.

On the other hand, when a mixed signal having a frequency fd is mixed, the two components cancel each other because the frequency components f2, f3, and f5 included in the RX signal output through the RX stage are opposite in phase and the same in magnitude. . However, in the case of the f4 and f6 frequency components included in the RX signal, only a part of the two signals are canceled because the phases of the two signals are opposite or different in magnitude. Accordingly, when the mixed signal having the fd frequency is mixed, the final result leaves only the signals corresponding to the f1-fd, f1, f4, f6, f7 and f7-fd frequency components. Here, the magnitudes of the f4 and f6 frequency components are smaller than the magnitudes of the f1-fd, f1, f7 and f7-fd frequency components.

Accordingly, it can be confirmed that the fifth TX electrode to which the TX signal of the f5 frequency, which is a value between the f4 frequency component and the f6 frequency component, is applied.

17 is a frequency spectrum for schematically illustrating an example of reconstructing a mixed signal by applying a filter when the mixing frequency of the mixed signal is greater than (maximum frequency of the TX signal-minimum frequency of the TX signal) / 2.

Referring to FIG. 17, when not mixed, frequency components f1, f2, f3, f4, f5, f6, and f7 exist in the RX signal output through the RX stage. Here, since the TX electrode for transmitting the TX signal having the f5 frequency component is touched, the f5 frequency component is smaller in size than other frequency components.

On the other hand, when the mixed signal is mixed, the frequency components of the positive phase are arranged in the frequency band higher than f7 and the frequency components of the negative phase are arranged in the frequency band lower than f1. Therefore, when the mixing frequency of the mixing signal is greater than (maximum frequency-minimum frequency of the TX signal) / 2, the mixed sensing signals are separated from each other on the frequency spectrum such that they cannot be canceled with each other.

Therefore, the frequency components of the positive phase or the frequency components of the negative phase can be detected, and the touch position can be confirmed based on the magnitude of the detected frequency components.

The frequency components of the positive phase may be detected by a high pass filter, and the frequency components of the negative phase may be detected by a low pass filter. The high pass filter or the low pass filter may be disposed in front of the input terminal to which the RX signal is input, may be disposed in front of the ADC block, or may be disposed in front of the FFT block.

18 is a diagram illustrating an example of reconstructing a touch original signal by multiplying the sine wave by the inverse of the sine wave multiplied by mixing in the time domain.

Referring to FIG. 18, there are f1- (fd / 2), f4 + (fd / 2), f5 + (fd / 2), and f1 + (fd / 2) frequency components in the mixed signal multiplied by the sine wave.

The magnitude of the f1- (fd / 2) frequency component and the magnitude of the f1 + (fd / 2) frequency component are the same, and the magnitude of the f4 + (fd / 2) frequency component and the magnitude of the f5 + (fd / 2) frequency component are the same. . Also, the magnitude of the f4 + (fd / 2) frequency component is smaller than the magnitude of the f1- (fd / 2) frequency component.

However, multiplying the sine wave by the inverse of the mixed signal reconstructs the original signal and detects the frequency components f1, f2, f3, f4, f5, f6, and f7. Here, the f5 frequency component is smaller in size than other frequency components. Accordingly, it can be seen that the TX electrode corresponding to the TX signal of the f5 frequency component is touched.

The capacitive touch system according to the present invention can be employed in various electronic devices including a display panel.

The electronic device may be, for example, a smartphone, a tablet PC, a mobile phone, a video phone, an e-book reader, a desktop PC, a laptop PC, a netbook computer, a workstation, a server, a personal digital assistant (PDA), and a portable multimedia. player, MP3 player, mobile medical device, camera, or wearable device (e.g. smart glasses, head-mounted-device (HMD)), electronic apparel, electronic bracelets, electronic necklaces, electronic accessories, It may include at least one of an electronic tattoo, a smart mirror, or a smart watch.

In addition, the electronic device may be a smart home appliance. Smart home appliances are, for example, televisions, digital video disk (DVD) players, audio, refrigerators, air conditioners, cleaners, ovens, microwaves, washing machines, air purifiers, set-top boxes, home automation control panels, security control panels. It may include at least one of a TV box, a game console, an electronic dictionary, an electronic key, a camcorder, or an electronic picture frame.

In addition, the electronic device may include various medical devices (e.g., various portable medical measuring devices such as blood glucose meters, heart rate monitors, blood pressure monitors, or body temperature meters), magnetic resonance angiography (MRA), magnetic resonance imaging (MRI), and CT (computed). tomography, cameras, or ultrasounds), navigation devices, GPS receivers, event data recorders (EDRs), flight data recorders (FDRs), automotive infotainment devices, ship electronics (e.g. ship navigation devices, gyro compasses, etc.) Electronics, security devices, vehicle head units, industrial or household robots, ATMs in financial institutions, point of sale stores, or Internet of Things devices (e.g. light bulbs, sensors, electric or gas meters, sprinkler devices, fire alarms) , Temperature controller, street light, toaster, exercise equipment, hot water tank, heater, boiler, and the like.

In addition, the electronic device may include at least one of a part of a furniture or a building / structure, an electronic board, an electronic sign receiving device, a projector, or various measuring devices (eg, water, electricity, gas, or radio wave measuring device). . The electronic device may be one or a combination of the above-described various devices. The electronic device may be a flexible electronic device. In addition, the electronic device is not limited to the above-described devices, and may include a new electronic device according to technology development.

As described above, according to the present invention, when the touch system adopts a multi-frequency driving scheme, a sinusoidal signal having a specific frequency is mixed with a signal applied to the TX stage or a signal output from the RX stage, and the touch circle To recover the signal, the inverse of the deconvolution or mixing signal can be multiplied to prevent the occurrence of charge overflow without lowering the frame rate or lowering the SNR.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

10, 110: touch panel 20, 120: TX drive unit
30, 140: RX receiver 40, 150: signal detector
130, 230: frequency mixing unit 510, 520, 530: ADC block
512, 522, 534: FFT block 514, 526, 536: signal detection block
524: Deconvolution block 532: Inverse sine wave processing block

Claims (15)

A touch panel including a plurality of TX electrodes and a plurality of RX electrodes;
A TX driver which provides TX signals having different frequencies to the TX electrodes, respectively;
An RX receiver configured to receive RX signals output from each of the RX electrodes;
A frequency mixing unit configured to mix a mixing signal having a specific frequency with each of the TX signals or the RX signals and output a mixed sensing signal; And
And a signal detector for reconstructing the touch original signal by separating the mixed signal from the mixed sensing signal, wherein the mixed signal includes a sine wave, and the frequency of the sine wave is 0.5 times to the minimum frequency of the minimum frequency intervals of the TX signals. Is an integer multiple of the interval,
The signal detection unit is a capacitive touch system, characterized in that for applying the deconvolution filter to reconstruct the touch original signal by calculating in the entire section where a plurality of TX signals in the frequency domain within the FFT result. The capacitive touch system of claim 1, wherein the frequency of the TX signals has any one of an equal interval, a minor interval, and a random interval. delete delete delete delete delete The method of claim 1, wherein the signal detection unit,
An ADC block for ADC converting the mixed sensing signal;
An FFT block for FFT processing the ADC converted signal; And
And a deconvolution block for deconvolving the FFT processed signal to detect the mixed sensing signal. delete delete Mixing a mixed signal having a specific frequency with each of the TX signals having different frequencies and outputting the mixed signal to the TX electrode; And
And reconstructing the touch original signal by separating the mixed signal from each of the mixed sensing signals output through the RX electrode, wherein the mixed signal includes a sine wave and the frequency of the sine wave is a minimum frequency interval of the TX signals. 0.5 times to an integer multiple of the minimum frequency interval,
Reconstructing the touch original signal,
Digitally converting each of the mixed sensing signals;
FFT processing each of the digitally converted sensing signals; And
A method of driving a capacitive touch system comprising deconvoluting an FFT processed mixed sensing signal to detect a touch original signal. Outputting TX signals having different frequencies to the TX electrode;
Mixing a mixed signal having a specific frequency with each of the RX signals output through the RX electrode and outputting a mixed sensing signal; And
And reconstructing the touch original signal by separating the mixed signal from each of the mixed sensing signals, wherein the mixed signal includes a sine wave, and the frequency of the sine wave is 0.5 times to a minimum of a minimum frequency interval of TX signals. Is an integer multiple of the frequency interval,
Reconstructing the touch original signal,
Digitally converting each of the mixed sensing signals;
FFT processing each of the digitally converted sensing signals; And
A method of driving a capacitive touch system comprising deconvoluting an FFT processed mixed sensing signal to detect a touch original signal.

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