KR20170073749A

KR20170073749A - Appratus of Capacitive Touch Panel and Method of driving the same

Info

Publication number: KR20170073749A
Application number: KR1020150181420A
Authority: KR
Inventors: 이주원; 이학충
Original assignee: 이주원; 이학충
Priority date: 2015-12-18
Filing date: 2015-12-18
Publication date: 2017-06-29

Abstract

A capacitive touch panel device and a driving method thereof are disclosed. In order to minimize the influence of the disturbance noise included in the received signal, an operation is performed on the digital code converted into the form of a digital signal. The information on the noise level of the digital code is compared with the reference value, and when it is determined that the frequency of the noise is similar to the frequency of the received signal, the frequency of the drive signal supplied from the signal generator is changed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to capacitive touch panel devices,

The present invention relates to a capacitance type touch panel and a driving method thereof, and more particularly, to a capacitive type touch panel device capable of selecting an optimum frequency and eliminating the influence of noise, &Lt; / RTI >

The touch panel is a device which is attached to a display device or the like as a contact sensing device and generates a signal related to whether or not the user touches the touch panel. Particularly, the touch panel is widely used for a smart phone, a PDA (Personal Digital Assistant) or a navigation system. The touch panel can be classified into a resistance film type and a capacitance type according to a method of detecting contact, and a capacitive touch panel having a simple structure and low power consumption is mainly used in portable electronic devices.

The capacitive touch panel is composed of a transfer electrode and a reception electrode with a dielectric interposed therebetween. The transfer electrode and the reception electrode are arranged in the form of a cross bar, and a capacitor component is formed by the transfer electrode, the reception electrode and the dielectric. When contact by the user occurs, the capacitor component is changed in size, and the changed capacitance is sensed through a change in the voltage applied between the transfer electrode and the reception electrode. Typically, a square wave transmission signal is transmitted through a transmission electrode, and a reception signal is sensed through a reception electrode.

The capacitive touch panel may include a noise component caused by a fluorescent lamp, an AC power source, or the like. That is, when a touch by a user occurs, the user acts as an antenna, and the noise is transmitted to the touch panel to cause a malfunction of the touch panel.

Korean Patent Publication No. 2012-0111910 discloses a touch panel device capable of reducing disturbance noise. In this patent, the subtraction circuit receives the output of the A / D conversion circuit. By the operation of the subtraction circuit, the respective noise components are subtracted from each other. This may result in the removal of noise components. On the other hand, the patent requires adjustment of the sampling timing in order to perform the subtraction of the noise. That is, the sampling operation is performed at the rising edge or the falling edge of the waveform in the signal transmitted from the receiving electrode. However, when a user touches, a capacitance is generated by a user in addition to an existing capacitor, so that a received signal is delayed for a predetermined time period compared to a transmission signal. Therefore, there is a disadvantage in that the delay time is not constant depending on various contact operations, and the sampling timing is difficult to be accurately applied to the received signal.

Also, Korean Patent Registration No. 1350673 discloses a technique for analyzing characteristics of a noise signal to adjust a transmission signal. In this patent, the characteristics of noise components of signals stored in a plurality of capacitors are determined by using an integrator. Thereby controlling the frequency of the transmission signal. In addition, the patent discloses only a configuration for generating a transmission signal having a frequency different from that of a conventional one through analysis of a noise component. In particular, the technique for selecting the optimum frequency is not disclosed.

As described above, the prior art attempts to minimize the influence of disturbance noise generated when a user touches. In order to minimize the disturbance noise, it is possible to remove the noise included in the received signal or to minimize the influence of the noise by changing the frequency. However, the above-described conventional techniques fail to provide an optimal method for removing noise components and have certain technical disadvantages.

SUMMARY OF THE INVENTION The present invention provides a touch panel device and a driving method thereof that can minimize the influence of disturbance noise.

According to an aspect of the present invention, there is provided a display device including a driver for generating a transmission signal for sensing a touch operation; A touch sensor unit having a transmission electrode and a reception electrode crossing each other and forming a reception signal according to a touch operation; A reception processor for receiving the received signal and amplifying the received signal to convert the received signal into a digital code; An optimum frequency generation unit for receiving the digital code from the reception processing unit and deriving a result of the digital code to discriminate a noise having a frequency similar to the frequency of the received signal and generating a frequency control signal according to a result of the determination; ; And a signal generating unit for generating a driving signal of a changed frequency by applying a frequency changing operation according to the frequency control signal to induce a frequency change of the transmission signal.

According to another aspect of the present invention, there is provided a method of controlling a mobile communication terminal, including: receiving a reception signal having a first frequency and including touch information; Processing the received signal and forming a digital code through digital conversion; Generating a frequency control signal by determining whether a frequency of a noise component included in the received signal is similar to a frequency of the received signal through an operation on the digital code; Generating a drive signal having a second frequency different from the first frequency according to the frequency control signal; And forming a transmission signal having the second frequency by using the driving signal having the second frequency. The present invention also provides a method of driving a touch panel device.

According to the present invention described above, when the frequency of the disturbance noise is similar to the frequency of the transmitted signal or the frequency of the received signal, the amplitude of the received signal is increased, and this is analyzed through an operation on the digital code in the optimum frequency generator. Further, the analyzed result is compared with the reference value, and the frequency of the driving signal supplied to the driving unit is changed. The operation of changing the frequency of the drive signal is performed until the result of the operation on the digital code is lower than a specific ratio with respect to the reference value. Accordingly, a transmission signal having a frequency different from the frequency of the noise is supplied to the touch sensor unit, and the influence of the disturbance noise is minimized.

The drive signal is not supplied in a fixed state but is changed according to the application state of the noise, so that the phenomenon that the sensitivity of the touch signal due to the influence of the noise is lowered or the malfunction is prevented is prevented. In addition, the accuracy of the touch operation is improved.

1 is a block diagram illustrating a touch panel device according to a preferred embodiment of the present invention.
2 is a block diagram illustrating an operation of a reception processing unit according to a preferred embodiment of the present invention.
3 is another block diagram for explaining the operation of the reception processing unit according to the preferred embodiment of the present invention.
4A to 4C are circuit diagrams illustrating the band-pass filter described in FIGS. 2 and 3 according to a preferred embodiment of the present invention.
5A to 5D are circuit diagrams illustrating the low-pass filter shown in FIGS. 2 and 3 according to a preferred embodiment of the present invention.
6 is a block diagram illustrating an operation of an optimum frequency generator according to a preferred embodiment of the present invention.
FIG. 7 is a block diagram illustrating the signal generator and the driver shown in FIG. 6 according to a preferred embodiment of the present invention.
8 and 9 are timing charts for explaining the operation of the touch panel device according to the preferred embodiment of the present invention.
10 and 11 are other timing charts for explaining the operation of the touch panel device according to the preferred embodiment of the present invention.
12 and 13 are other timing charts for explaining the operation of the touch panel device according to the preferred embodiment of the present invention.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

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 to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

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

Example

1 is a block diagram illustrating a touch panel device according to a preferred embodiment of the present invention.

Referring to FIG. 1, the touch panel device includes a driving unit 100, a touch sensor unit 200, a reception processing unit 300, an optimum frequency generation unit 400, and a signal generation unit 500.

The driving unit 100 receives the driving signal Drf applied from the signal generating unit 500 and generates a pulse signal of a pulse wave, a square wave or a sawtooth wave at a specific frequency. The driving unit 100 has a driving driver corresponding to each of the transmitting electrodes 201, 202 and 203 for transmitting the transmitting signal Tx. That is, the driving signal Drf may have various forms and may have various waveforms, for example, a pulse wave, a square wave, or a sawtooth wave.

The touch sensor unit 200 has a plurality of transmitting electrodes 201, 202 and 203 and receiving electrodes 211, 212 and 213. Each of the transmission electrodes 201, 202, and 203 and the reception electrodes 211, 212, and 213 are disposed in an intersecting shape to form a capacitance at an intersection point. In addition, the transmitting electrodes 201, 202, and 203 are arranged with a predetermined distance from each other in a shape elongated in the first direction. In addition, the receiving electrodes 211, 212, and 213 have a shape elongated in a second direction substantially perpendicular to the first direction, and are disposed with a predetermined distance from each other. Transmitting signals Tx [1], Tx [2], and Tx [3] are applied to the transmitting electrodes 201, 202 and 203 from the driving unit 100, Receive signals Rx [1], Rx [2], and Rx [3] are output.

When a touch operation by the user occurs, the capacitance of the corresponding coordinate is changed. In a typical case, the amplitude of the received signal Rx is reduced by the changed capacitance. Also, the applied transmission signals Tx may be applied in a scanning manner having a constant phase difference in comparison with the adjacent transmission signals. In addition, the transmission signals Tx are applied with a predetermined frequency, and a signal having substantially the same frequency as the transmission signal Tx also appears in the reception signals Rx.

Further, when a noise having a frequency similar to the frequency of the transmission signal Tx due to various causes such as a user is drawn, a signal having an increased amplitude or a signal having a reduced amplitude appears in the reception signals Rx. That is, when no noise is introduced, the received signals Rx tend to converge to a certain level, but when noise is introduced, fluctuations appear in the received signals Rx.

The reception processing unit 300 receives the reception signals Rx and converts the reception signals Rx into digital signals through a predetermined signal processing operation. The reception signal Rx has a lower amplitude than the transmission signal Tx. This is a result of the capacitance component of the touch sensor unit 200, which is an impedance component. The reception signal Rx whose amplitude is lower than that of the transmission signal Tx is amplified to a predetermined gain by the reception processing section 300. [

Also, the amplified received signal is formed into a waveform that oscillates (+) and (-) around the ground level AC. Which is again shaped into a waveform oscillating in one of the (+) direction or the (-) direction through a calculation operation with the drive signal Drf or the frequency control signal Fctl. For example, the amplified received signal can be shaped into a sawtooth wave, which is a waveform that oscillates only in one direction (+). This is called the demodulator output signal.

The demodulator output signal is filtered through a low-pass filter and converted to a digital code ADC_OUT. The converted digital code ADC_OUT has touch information of the corresponding touch sensor unit 200.

The optimum frequency generation unit 300 derives a noise component from the received digital code ADC_OUT and compares it with a reference value. That is, if the resultant value of the digital code ADC_OUT is derived and the resultant value is more than a specific ratio with respect to the reference value, the optimum frequency generating unit 300 generates a frequency control signal Fctl for changing the frequency. The generated frequency control signal Fctl is applied to the signal generator 500.

The signal generating unit 500 receives the frequency control signal Fctl and applies the driving signal Drf according to the received frequency control signal Fctl to the driving unit 100. [ The drive signal Drf is preferably a square wave having a specific frequency generated by the frequency control signal Fctl.

1, the optimum frequency generation unit 400 stores and analyzes the digital code ADC_OUT input from the reception processing unit 300 to determine an optimum frequency. For example, when the transmission signal Tx having the first frequency is applied to the touch sensor unit 200 and the reception signal Rx of the first frequency is output from the touch sensor unit 200, the reception signal Rx is converted into the digital code ADC_OUT And transmitted to the optimum frequency generation unit 400.

The optimum frequency generation unit 400 analyzes a noise component having a frequency similar to the reception signal Rx having the first frequency and compares the noise component with a reference value. That is, information on the noise level is derived from the digital code ADC_OUT, and if the information on the derived noise level shows a value higher than a predetermined level with respect to the reference value, the optimum frequency generating unit 400 generates a frequency- And generates a drive signal Drf having another second frequency. The above operation is performed until the influence of the noise component of the digital code ADC_OUT input to the optimum frequency generator 400 is removed. The frequency changing operation of the driving signal Drf is repeated until, for example, the information on the noise level of the digital code ADC_OUT according to the changed frequency shows a variation below a certain level with respect to the reference value.

2 is a block diagram illustrating an operation of a reception processing unit according to a preferred embodiment of the present invention.

Referring to FIG. 2, the reception processing unit includes an amplifier 310, a demodulator 320, a low-pass filter 330, and an analog-to-digital converter 340.

The amplifier 310 amplifies the received signal Rx with a predetermined gain. The amplified reception signal has the same frequency as the transmission signal Tx or the driving pulse signal Drf and has an increased amplitude as compared with the reception signal Rx. Also, the amplified received signal has a waveform shape that alternates between (+) and (-) with respect to AC ground.

Subsequently, the amplified reception signal is input to the demodulator 320. A driving signal Drf or a frequency control signal Fctl is input to the demodulator 320, and an amplified reception signal is also input. That is, since the drive signal Drf or the frequency control signal Fctl applied to the demodulator 320 have the same frequency, no problem occurs in operation even when any signal is applied. The applied signals are converted into a signal having a phase in a specific one direction through a multiplication operation or an inversion of a waveform in a specific region. For example, the demodulator 320 may invert a waveform of a specific phase through operation of a mixer. In other words, the demodulator 320 can be configured as a signal having a phase in a certain direction. For example, the demodulator output signal may be converted into a signal having a phase in the (+) direction.

The demodulator output signal is input to the low pass filter 330. The low pass filter 330 performs a filtering operation to remove high frequency components from the demodulator output signal components. The filtered signal, which is the filtered demodulator output signal, is input to the analog-to-digital converter 340.

The analog-to-digital converter 340 converts the filtered signal to a digital code ADC_OUT using a sampling operation. The converted digital code ADC_OUT includes noise components and touch information input from the touch sensor unit 200.

In FIG. 2, a band pass filter may be provided between the amplifier and the demodulator, and a band pass filter may be provided between the demodulator and the analog-to-digital converter. The provided band-pass filter is used to remove the noise component included in the received signal Rx.

3 is another block diagram for explaining the operation of the reception processing unit according to the preferred embodiment of the present invention.

3, the reception processing unit has a plurality of reception paths 351 and 352, a multiplexer 341, and an analog-to-digital converter 340. [

Each receive path 351, 352 is input to a multiplexer 341 and is connected in parallel with one another. Each of the reception paths 351 and 352 is provided with amplifiers 311 and 312, demodulators 321 and 322 and low-pass filters 331 and 332.

For example, the first reception signal Rx [1] is input to the first reception path 351, and the processing of the signal shown in FIG. 2 is generated. Also, the processing of the signals for the received signals Rx {1], ..., Rx {n] is performed up to the n-th received signal Rx [n]. Signals passing through the low pass filters 331 and 332 in the respective receive paths 351 and 352 are applied to the multiplexer 341.

The multiplexer 341 receives the signals output from the respective reception paths 351 and 352, and selects and outputs a specific one of the signals. The output signal is applied to the analog-to-digital converter 340. According to the embodiment, the multiplexer 341 can select signals of a plurality of reception paths, and the analog-to-digital converter 340 can be provided correspondingly according to the number of signals selected at the same time.

In addition, a bandpass filter may be provided in each of the reception paths 351 and 352 as described in FIG. For example, between the amplifiers 311 and 312 and the demodulators 321 and 322 in the respective receiving paths or between the demodulators 321 and 322 and the low-pass filters 331 and 332.

4A to 4C are circuit diagrams illustrating the band-pass filter described in FIGS. 2 and 3 according to a preferred embodiment of the present invention.

Referring to FIG. 4A, the band-pass filter has a configuration of a Shallen-key topology. The filter has the characteristics of a secondary filter, and the frequency characteristics for bandpass are determined according to the values of R, C, R1 and R2.

Referring to FIG. 4B, the bandpass filter has a configuration of multiple feedback filters. The multiple feedback filter has a transfer function according to the following equation (1).

[Equation 1]

As shown in Equation (1), the transfer function has the characteristics of a second-order filter, and the characteristics of the band-pass filter are determined according to the values of C, R1, R2, and R3.

Referring to FIG. 4C, the band-pass filter may have a structure of a Gm-C filter. The Gm-C filter has a property of a quadratic transfer function by C1 and C2. Therefore, the characteristics of the band-pass filter can be determined according to the values of Rbias, C1, and C2.

4A to 4C illustrate examples in which the bandpass filter can be used. In addition, various bandpass filters may be used.

5A to 5D are circuit diagrams illustrating the low-pass filter shown in FIGS. 2 and 3 according to a preferred embodiment of the present invention.

FIG. 5A shows a first-order low-pass filter, and FIG. 5B shows a Shallen-key filter. It is well known that the filter of FIG. 5B can implement a low-pass filter according to the value of the resistor and the capacitor. 5C shows a multiple feedback filter, and FIG. 5D shows a Gm-C filter. Implementations of the low-pass filter in the filters shown in Figures 5C and 5D may be implemented by adjusting the values of the resistors and capacitors.

6 is a block diagram illustrating an operation of an optimum frequency generator according to a preferred embodiment of the present invention.

Referring to FIG. 6, the optimal frequency generator includes a memory 410, a noise calculator 420, a data comparator 430, and a frequency selector 440.

The memory 410 stores a digital code ADC_OUT. That is, all data of the touch sensor unit 200 constituting the touch panel is stored in the memory 410. The unit stored in the memory 410 may be a digital code corresponding to one receiving electrode. That is, all the touch information received from the touch sensor unit 200 is stored in the memory 410.

The noise calculator 420 extracts information on the noise level of the touch information in the digital code form stored in the memory 410. Normally, when the noise applied from the outside has a frequency similar to the transmission signal Tx or the reception signal Rx, the reception signal Rx level decreases or increases. Also, when there is no noise, a characteristic of converging to a certain voltage appears. That is, the component of the received signal Rx increased by the noise causes an increase in information on the noise level. Information on the noise level calculated by the noise calculation unit 420 is input to the data comparison unit 430. [ The information on the noise level may be an average value, a median value, a minimum value, a standard deviation, or a maximum value of the digital code ADC_OUT.

The average value of the digital code ADC_OUT is a value obtained by dividing the sum of the digital codes ADC_OUT by the number of data, and the median value is a value obtained by dividing the values of the digital code ADC_OUT by half in the number of data by a value equal to or greater than a specific digital code, Refers to a value that is less than or equal to the digital code. Also, the most frequent value represents the most observed value among the values of the digital code ADC_OUT. Also, the standard deviation indicates how far the values of the digital code ADC_OUT are away from the average, and the maximum value indicates the maximum value of the values of the digital code ADC_OUT.

The designer can convert information about the noise level into various forms according to the shape of the touch panel and the state of the noise.

The data comparing unit 430 compares information on the noise level of the inputted digital form with a reference value. The degree of intervention of the noise converted into the digital form through the comparison operation of the data is compared with the reference value. Generally, when the touch sensor unit 200 is touched through the finger of the human body and when the touch is not made, approximately 10% of the measured digital code is varied.

For example, the reference value is set to a digital code of a received signal Rx that is input from the touch sensor unit 200 when no touch is made and which is converted into a digital code or noise is not intervened, and the information about the measured noise level Is determined. For example, the variation amount of the digital code due to the influence of the external noise input at the time of touch based on the digital code measured in the non-touched state can be measured and judged. The upper limit of the variation based on the reference value for judgment may be variously changed according to the state of the touch panel.

For example, when the information on the noise level appears as a standard deviation, the reference value is set to a reference value in which a noise is not intervened or a digital code in which no touch is generated. For example, if the measured standard deviation is 5% or more of the reference value, the data comparison unit 430 determines that the noise is distributed in the same frequency domain as the transmission signal Tx to which the noise is applied. The signal determined by the data comparison unit 430 is applied to the frequency selection unit 440. The standard deviation is given by the following equation (2).

&Quot; (2) "

In Equation 2 K is the standard deviation, m represents a respective digital code corresponding to the number of digital codes, ADCavg is the average value of the digital code, ADC _i.

However, in this embodiment, information on the noise level can be calculated in various ways, and comparison with the reference value according to the standard deviation is an embodiment. It will be apparent to those skilled in the art that the reference for judging that noise is introduced when compared with the reference value can be variously set according to the form and state of the touch panel.

The frequency selection unit 440 receives the determination signal from the data comparison unit 430 and generates the frequency control signal Fctl. The generated frequency control signal Fctl may be any signal that can induce a frequency different from the transmission signal Tx corresponding to the measured data. Accordingly, the frequency selector 440 generates the frequency control signal Fctl that can induce the change of the transmission frequency. The generated frequency control signal Fctl is applied to the signal generator 500.

For example, the frequency control signal Fctl may have various waveforms and may be a signal having a specific frequency. That is, the frequency selecting unit 440 can divide the frequencies within the range of 100 Hz to 10 MHz into arbitrary numbers and select them to avoid the representative frequency of 60 Hz, which is the noise signal.

FIG. 7 is a block diagram illustrating the signal generator and the driver shown in FIG. 6 according to a preferred embodiment of the present invention.

Referring to FIG. 7, the signal generator 500 has a modulator 551. A frequency control signal Fctl and a waveform signal are applied to the modulator 551. The frequency control signal Fctl may be any signal having a frequency, but is a signal having a frequency changed by the frequency selection unit 440. [ A waveform signal is applied to the modulator 551. The waveform signal determines the type of the driving signal Drf formed in the signal generator 500. For example, the drive signal Drf may be a pulse wave, a square wave, or a sawtooth file. If the modulator 551 takes the form of a mixer and the frequency control signal Fctl forms a periodic wave through on / off operation of the switch, the waveform signal may be a signal set to a certain level, May be a pulsating signal, and may be a signal that repeats multiple levels.

The driving signal Drf is formed by the signal generating unit 500 and applied to the driving unit 100. The driving unit 100 forms a transmission signal Tx and may include an analog buffer or a digital buffer depending on the type of the driving signal Drf. For example, when the drive signal Drf is a sinusoidal wave or a sawtooth wave, an analog buffer is used, and when the drive signal Drf is a rectangular wave, a digital buffer can be used.

That is, the signal generator 500 performs the frequency changing operation according to the received frequency control signal Fctl to generate the driving signal Drf. The drive signal Drf may be a pulse wave, a square wave, or a sawtooth file having a frequency changed in accordance with the frequency control signal Fctl.

8 and 9 are timing charts for explaining the operation of the touch panel device according to the preferred embodiment of the present invention. 8 and 9 are timing charts illustrating the case where the touch panel device performs sequential driving.

First, referring to FIG. 8, a transmission signal Tx is applied in synchronization with the scanning signal Hsync. The transmission signal Tx is transmitted corresponding to each transmission line. That is, in the section in which the scanning signal Hsync activates the k-th transmission signal Tx [k], the transmission signal Tx [k] is transmitted to the k-th transmission line. The transmission signal Tx [k + 1] is sequentially transmitted to the (k + 1) th transmission line.

When noise enters the touch sensor unit and the introduced noise has a frequency similar to the transmission signal Tx, the amplitude of the reception signal Rx increases. That is, when the noise has the same or similar frequency as the transmission signal Tx, the amplitude of the reception signal Rx increases due to superposition of the waveform.

Therefore, the amplitude of the amplified received signal output from the amplifier 310 of FIG. 2 is slightly increased. Further, the demodulator 320 inverts the waveform of the (-) phase at the output of the amplifier 310 so as to have a (+) phase.

Subsequently, the filtered signal through the low-pass filter 340 becomes a form in which the high-frequency component is removed from the output of the demodulator 320. The signal passed through the low-pass filter 330 is converted into a digital code ADC_OUT by the analog-to-digital converter 340, and is input to the optimum frequency generator 400 of FIG.

All of the information of the touch sensor unit 200 constituting the panel is stored in the optimal frequency generation unit 400 and the influence of the noise is evaluated by deriving information on the noise level. Information on the extracted noise level is compared with a reference value. The reference value is data when there is no touch or no noise intervening. When a variation of a predetermined value or more occurs with respect to the reference value, it is determined that the frequency of the noise component is similar to the frequency of the transmission signal Tx. Therefore, the frequency selecting unit 440 of the optimum frequency generating unit 400 varies the frequency of the driving signal Drf through the frequency control signal Fctl. When the frequency of the driving signal Drf is varied and the frequency difference between the noise and the transmission signal Tx increases, the variation of the amplitude in the reception signal Rx due to the noise component is reduced.

The above-described operation is repeated until the information on the measured noise level has a variation within a predetermined value from the reference value.

Referring to FIG. 9, a transmission signal Tx with a changed frequency is applied. The reception signal Rx has the same frequency as that of the transmission signal Tx. The received signal Rx has a frequency capable of canceling the applied noise component. Thus, the output of the low-pass filter hardly shows a noise component, and the influence of noise is minimized. The information on the noise level measured by the changed frequency indicates a variation within a predetermined value from the reference value. This minimizes the effect of disturbance noise.

Also, the method of varying the frequency can be performed in various forms. For example, the frequency can be gradually increased through the frequency control signal Fctl, or conversely, the frequency can be reduced.

10 and 11 are other timing charts for explaining the operation of the touch panel device according to the preferred embodiment of the present invention. 10 and 11 show that the touch panel device operates in a simultaneous driving manner.

First, referring to FIG. 10, the scan signal Hsync is synchronized and the transmit signal Tx is simultaneously applied to all the transmission lines. However, since the applied transmission signals are applied in a matrix type, the transmission signals applied to the respective transmission lines may have a certain pattern. Also, according to the simultaneous driving method, a plurality of transmission signals are simultaneously applied to the transmission lines. In particular, the signals transmitted in FIGS. 10 and 11 are described as waveforms having no constant repetition period. This is due to the transmission signal being applied in the form of a constant matrix. Therefore, when the frequency of the transmission signal is referred to, it is assumed that it is the same as the frequency of the driving signal Drf used to form the transmission signal.

When noise enters the touch sensor unit and the introduced noise has a frequency similar to the transmission signal Tx, the amplitude of the reception signal Rx increases. The amplitude of the reception signal Rx is increased by superimposition of the waveforms when the noise has the same or similar frequency as the transmission signal Tx as compared with the normal case.

All of the information of the touch sensor unit 200 constituting the panel is stored in the optimal frequency generation unit 400 and the influence of the noise is evaluated by deriving information on the noise level. Information on the extracted noise level is compared with a reference value. The reference value is data when there is no touch or no noise intervening. When a variation of a predetermined value or more occurs with respect to the reference value, it is determined that the frequency of the noise component is similar to the frequency of the transmission signal Tx. Therefore, the frequency selecting unit 440 of the optimum frequency generating unit 400 varies the frequency of the driving signal Drf through the frequency control signal Fctl.

Referring to FIG. 11, a transmission signal Tx with a changed frequency is applied. The reception signal Rx has the same frequency as that of the transmission signal Tx. The received signal Rx has a frequency capable of canceling the applied noise component. Thus, the output of the low-pass filter hardly shows a noise component, and the influence of noise is minimized. The information on the noise level measured by the changed frequency indicates a variation within a predetermined value from the reference value. This minimizes the effect of disturbance noise.

12 and 13 are other timing charts for explaining the operation of the touch panel device according to the preferred embodiment of the present invention. 12 and 13 illustrate that the touch panel device operates in a block-driven manner.

In the block driving method, a continuous transmission electrode is bundled into one block and a transmission signal is simultaneously transmitted. Accordingly, a plurality of blocks are set, a sequential driving method is applied between a plurality of blocks, and a simultaneous driving method is applied to transmitting electrodes in one block.

In FIG. 12, the kth transmission electrode and the (k + 1) th transmission electrode are set as one block. Therefore, the transmission signal Tx [k] applied to the k-th transmission electrode and the transmission signal Tx [k + 1] applied to the (k + 1) -th transmission electrode are simultaneously applied. The received signal Rx is in a state in which noise is interfered by a touch.

In the optimum frequency generation unit 400, information on the extracted noise level is compared with a reference value. The frequency selection unit 440 of the optimum frequency generation unit 400 changes the frequency of the driving signal Drf through the frequency control signal Fctl.

In Fig. 13, the transmission signals and reception signals resulting from the driving signal Drf having the changed frequency are started using the changed frequency control signal Fctl. It can be seen that the noise component is minimized at the output of the demodulator and the noise component is minimized at the output of the low-pass filter by the drive signal Drf having the changed frequency.

The influence of the touch sensing operation is minimized even when noise is involved through the above-described operation. In the present invention, the driving signal is not supplied in a fixed state but is changed according to the applied state of the noise. Thus, the sensitivity of the touch signal due to the influence of noise can be lowered, malfunctions can be prevented, and the accuracy of the touch operation can be secured.

100: driving unit 200: touch sensor unit
300: reception processor 400: optimum frequency generator
500:

Claims

A driving unit for generating a transmission signal for sensing a touch operation;
A touch sensor unit having a transmission electrode and a reception electrode crossing each other and forming a reception signal according to a touch operation;
A reception processor for receiving the received signal and amplifying the received signal to convert the received signal into a digital code;
The digital code is input from the reception processing unit, and information on a noise level with respect to the digital code is derived to discriminate a noise having a frequency similar to the frequency of the received signal, and an optimum A frequency generator; And
And a signal generator for generating a drive signal of a changed frequency by applying a frequency change operation according to the frequency control signal to induce a frequency change of the transmit signal.

2. The apparatus of claim 1,
A memory for storing the digital code;
A noise calculator for deriving information on the noise level from the digital code stored in the memory;
A data comparing unit for determining whether a frequency of a noise included in the received signal is similar to a frequency of the received signal through a comparison operation between information on a noise level of the digital code and a reference value; And
And a frequency selection unit for generating the frequency control signal for changing the frequency of the driving signal according to the determination result of the data comparison unit.

3. The touch panel device according to claim 2, wherein the reference value is a digital code when no touch operation has occurred, or a digital code when noise is not intervened.

The touch panel device according to claim 3, wherein the information on the noise level of the digital code is an average value, a median value, a minimum value, a standard deviation, or a maximum value of a digital code when a touch is generated.

5. The method of claim 4, wherein when the information on the noise level of the digital code exhibits a variation of more than a predetermined value from the reference value, the data comparator determines that the frequency of the noise is similar to the frequency of the received signal. Panel device.

The apparatus as claimed in claim 1,
An amplifier for amplifying the received signal;
A demodulator for generating a signal having a phase in one direction with respect to an output of the amplifier;
A low-pass filter for removing a high-frequency component from an output of the demodulator; And
And an analog-to-digital converter for converting the output of the low-pass filter to a digital code through digital conversion.

The touch panel device of claim 6, wherein the driving signal or the frequency control signal is applied to the demodulator.

The touch panel device of claim 6, further comprising a band-pass filter between the amplifier and the demodulator, or between the demodulator and the low-pass filter, for passing only a frequency signal of a specific frequency band.

The apparatus as claimed in claim 1,
A plurality of receiving paths connected in parallel with each other;
A multiplexer for receiving an output signal of the receive path and selecting a signal of a specific receive path; And
And an analog-to-digital converter for converting the output of the multiplexer into a digital code through a digital conversion to an output of the multiplexer.

10. The method of claim 9,
An amplifier for amplifying the received signal;
A demodulator for generating a signal having a phase in one direction with respect to an output of the amplifier; And
And a low-pass filter for removing a high-frequency component from the output of the demodulator.

11. The touch panel device according to claim 10, wherein the driving signal or the frequency control signal is applied to the demodulator.

The touch panel device according to claim 10, further comprising a band-pass filter capable of passing only a frequency signal of a specific frequency band between the amplifier and the demodulator or between the demodulator and the low-pass filter.

Receiving a reception signal having a first frequency and including touch information;
Processing the received signal and forming a digital code through digital conversion;
Generating a frequency control signal by determining whether a frequency of a noise component included in the received signal is similar to a frequency of the received signal through an operation on the digital code;
Generating a drive signal having a second frequency different from the first frequency according to the frequency control signal; And
And forming a transmission signal having the second frequency using the driving signal having the second frequency.

14. The method of claim 13, wherein generating the frequency control signal comprises:
Storing the digital code;
Obtaining information on a noise level of the stored digital code;
Comparing information on the noise level with a reference value to determine whether a frequency of a noise component included in the received signal is similar to a frequency of the received signal; And
And generating the frequency control signal in accordance with a comparison result between the information on the noise level and the reference value.

15. The driving method of a touch panel device according to claim 14, wherein the reference value is a digital code in the case where the touch operation does not occur or a digital code in which no noise is interposed.

The touch panel device according to claim 15, wherein when the information on the noise level of the digital code exhibits a variation of more than a predetermined value with respect to the reference value, it determines that the frequency of the noise is similar to the frequency of the received signal Driving method.

17. The method of claim 16, wherein if the frequency of the noise is similar to the frequency of the received signal, the frequency control signal has the second frequency.

14. The method of claim 13, further comprising the step of applying a driving signal having a first frequency to the touch sensor unit before the step of receiving the reception signal.

19. The method of claim 18, wherein the driving signals are sequentially transmitted to the respective transmission electrodes by a sequential driving method.

19. The method of claim 18, wherein the driving signal is simultaneously transmitted to all the transmitting electrodes by a simultaneous driving method.

19. The method of claim 18, wherein the driving signal is simultaneously transmitted to the transmission electrodes set as one block by a block driving method, and sequentially supplied between the blocks.

Wherein processing the received signal and forming the digital code further comprises:
Amplifying the received signal;
Converting the amplified received signal into a waveform having a specific phase;
Performing a filtering operation to remove a high frequency component from a waveform having the specific phase; And
And performing digital conversion on the filtered signal to form the digital code.

23. The touch panel device according to claim 22, wherein the step of converting the amplified received signal into a waveform having a specific phase performs a multiplication operation with the amplified received signal using the frequency control signal Driving method.

23. The method of claim 22, further comprising the step of passing only a signal of a specific frequency band in a previous step or a subsequent step of converting the amplified received signal into a waveform having a specific phase, Way.