WO2021172730A1

WO2021172730A1 - Touch sensor and driving method therefor

Info

Publication number: WO2021172730A1
Application number: PCT/KR2020/095037
Authority: WO
Inventors: 박지헌
Original assignee: 주식회사 에이코닉
Priority date: 2020-02-28
Filing date: 2020-03-13
Publication date: 2021-09-02
Also published as: KR102186177B1

Abstract

The present invention relates to a touch sensor comprising: a touch sensing unit including driving electrodes and sensing electrodes that cross each other; a touch driving unit for supplying touch driving signals to the driving electrodes; and a capacitance sensing unit for receiving a sensing signal from an i-th sensing electrode of the sensing electrodes and outputting the capacitance corresponding to the sensing signal, wherein the capacitance sensing unit comprises: an amplifier for receiving the sensing signal of the i-th sensing electrode; a mixer circuit unit for demodulating the output signal of the amplifier so as to form an in-phase signal and a quadrature signal; and a signal magnitude calculation unit for calculating the magnitude of an I/Q signal including the in-phase signal and the quadrature signal, and outputting the calculated magnitude of I/Q signal as the capacitance corresponding to the sensing signal of the i-th sensing electrode.

Description

Touch sensor and driving method thereof

The present invention relates to a touch sensor and a driving method thereof, and more particularly, to a touch sensor capable of recovering capacitance without signal loss regardless of a phase delay and a driving method thereof.

The touch sensor senses a user's touch by using a resistive method, a capacitive method, or an infrared method. Recently, the capacitive method, especially the mutual capacitance method, which has advantages such as excellent visibility and multi-touch function, has been mainstream in the mid- and small-sized mobile products.

In the case of a capacitive touch sensor, an error may occur in touch recognition due to the influence of ambient noise due to the driving principle. The ambient noise of the touch sensor typically includes noise caused by a display operation to which the touch sensor is mainly applied, noise generated from a fluorescent lamp, and noise generated from a three-wavelength lamp.

Such ambient noise has a specific frequency component, and when it overlaps with a frequency band used for the operation of the touch sensor, it causes interference, making it difficult to sense the touch position. Therefore, in order to avoid noise interference, a frequency hopping method of changing a frequency used for driving a touch sensor is used.

However, since the phase delay of the driving signal is generated due to the parasitic resistance component and the parasitic capacitance component of the touch sensor, a later sensing circuit reflects the phase delay and converts the capacitance modulated with the frequency of the driving signal to a mixer. must be restored through

However, when the frequency hopping method is employed, since it is necessary to individually estimate and calculate the phase delay for each driving frequency, there is a problem in that the complexity of the circuit structure increases.

An object of the present invention devised to solve the above problems is to provide a touch sensor capable of restoring capacitance without signal loss regardless of phase delay by demodulating a detection signal into an in-phase signal and a quadrature signal, and a method for driving the same it is to do

Another object of the present invention is to provide a touch sensor capable of distinguishing between a touch normally generated by a user and a touch abnormally generated by water droplets, and a method of driving the same.

A touch sensor according to an embodiment of the present invention includes a touch sensing unit including driving electrodes and sensing electrodes crossing each other, a touch driving unit supplying a touch driving signal to the driving electrodes, and an i-th sensing among the sensing electrodes. and a capacitive sensing unit receiving a sensing signal from the electrode and outputting a capacitance corresponding to the sensing signal, wherein the capacitive sensing unit includes an amplifier receiving the sensing signal of the i-th sensing electrode, and an output signal of the amplifier A mixer circuit for demodulating into an in-phase signal and a quadrature signal, and calculating the magnitude of an I/Q signal composed of the in-phase signal and the quadrature signal, and the calculated I/Q and a signal magnitude calculator for outputting the magnitude of the signal as a capacitance corresponding to the detection signal of the i-th detection electrode.

Also, the signal magnitude calculator may calculate the magnitude of the I/Q signal by adding a preset offset value to the I/Q signal.

In addition, the mixer circuit unit receives a first demodulated signal having the same phase as the touch driving signal and a second demodulated signal having a phase difference of 90 degrees from the touch driving signal, and generates the first demodulated signal and the second demodulated signal. can be used to perform the demodulation operation.

Also, the touch driving unit may change the frequency of the touch driving signal.

Also, the signal magnitude calculator may change the offset value in response to a change in the frequency of the touch driving signal.

Also, the offset value may include an offset value added to the in-phase signal and an offset value added to the quadrature signal.

In addition, the mixer circuit unit includes a first mixer for mixing the output signal of the amplifier with the first demodulated signal to output the in-phase signal, and a first analog-to-digital converter for converting the in-phase signal into a digital signal and outputting it , a second mixer for mixing the output signal of the amplifier with the second demodulated signal to output the quadrature signal, and a second analog-to-digital converter for converting the quadrature signal into a digital signal and outputting it .

In addition, the mixer circuit unit includes an analog-to-digital converter for converting the output signal of the amplifier into a digital signal, and a first for demodulating a signal output from the analog-to-digital converter into the in-phase signal using the first demodulated signal. a multiplier, and a second multiplier that demodulates a signal output from the analog-to-digital converter into the quadrature signal using the second demodulated signal.

A method of driving a touch sensor according to an embodiment of the present invention includes supplying a touch driving signal of a first frequency to driving electrodes, and first sensing from an i-th sensing electrode among sensing electrodes crossing the driving electrodes. inputting a signal to an amplifier; demodulating an output signal of the amplifier into a first in-phase signal and a first quadrature signal; the first in-phase signal and the first quadrature signal The magnitude of the first I/Q signal is calculated by adding a first offset value to the first I/Q signal composed of the signal, and the calculated magnitude of the first I/Q signal corresponds to the first detection signal. outputting with a capacitance of demodulating the output signal of the amplifier into a second in-phase signal and a second quadrature signal, and a second offset preset to a second I/Q signal composed of the second in-phase signal and the second quadrature signal calculating the magnitude of the second I/Q signal by adding values, and outputting the calculated magnitude of the second I/Q signal as a capacitance corresponding to the second sensing signal, wherein the second offset value may be set to be different from the first offset value.

In addition, demodulating the output signal of the amplifier into a first in-phase signal and a first quadrature signal, and converting the output signal of the amplifier into a second in-phase signal and a second quadrature signal The demodulation may include performing a demodulation operation using a first demodulated signal having the same phase as the touch driving signal and a second demodulating signal having a phase difference of 90 degrees from the touch driving signal.

According to the present invention as described above, it is possible to provide a touch sensor capable of restoring capacitance without signal loss regardless of a phase delay by demodulating a detection signal into an in-phase signal and a quadrature signal, and a method for driving the same.

In addition, according to the present invention, it is possible to provide a touch sensor capable of distinguishing between a touch normally generated by a user and a touch abnormally generated by water droplets, and a method of driving the same.

1 is a view showing a touch sensor according to an embodiment of the present invention.

2 is a diagram illustrating in more detail a touch sensing unit according to an embodiment of the present invention.

3 is a diagram showing in more detail the configuration of the capacitive sensing unit and the touch driving unit according to an embodiment of the present invention.

4A and 4B are diagrams illustrating I/Q signals according to an embodiment of the present invention.

5 is a diagram illustrating an I/Q signal when a normal touch and an abnormal touch occur together according to an embodiment of the present invention.

6 is a diagram illustrating an I/Q signal in a state in which an offset value is added according to an embodiment of the present invention.

7 is a diagram illustrating an I/Q signal in a state in which an offset value is added according to another embodiment of the present invention.

8 is a diagram illustrating in more detail the configurations of a capacitance sensing unit and a touch driving unit according to another embodiment of the present invention.

9 is a flowchart illustrating a method of driving a touch sensor according to an embodiment of the present invention.

Hereinafter, embodiments related to the present invention are illustrated in the drawings and will be described in detail through detailed description. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention. .

In describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the components from other components, and the essence, order, or order of the components are not limited by the terms. In addition, in this specification, when it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but each component It should be understood that another element may be “connected”, “coupled” or “connected” between elements. In the case of "connected", "coupled" or "connected", it is understood to be physically "connected", "coupled" or "connected" as well as electrically "connected", "coupled" or "connected" as needed. can be

Terms such as "~ unit (unit)", "~ group", "~ child", "~ module", etc. described in this specification mean a unit that processes at least one function or operation, which is hardware, software, or hardware and a combination of software. In addition, terms such as "comprises", "comprises" or "have" described in the present specification, unless otherwise stated, mean that the corresponding component may be embedded, so other components are excluded. Rather, it should be construed as being able to include other components further.

In addition, it is intended to clarify that the classification of the constituent parts in the present specification is merely a classification for each main function that each constituent unit is responsible for. That is, two or more components to be described below may be combined into one component, or one component may be divided into two or more for each more subdivided function. In addition, each of the constituent units to be described below may additionally perform some or all of the functions of other constituent units in addition to the main function it is responsible for. Of course, it may be carried out by being dedicated to it.

Hereinafter, a touch sensor and a driving method thereof according to an embodiment of the present invention will be described with reference to drawings related to embodiments of the present invention.

FIG. 1 is a view showing a touch sensor according to an embodiment of the present invention, and FIG. 2 is a view showing a touch sensing unit according to an embodiment of the present invention in more detail.

Referring to FIG. 1 , a touch sensor 100 according to an embodiment of the present invention may include a touch sensing unit 110 and a touch control unit 120 .

The touch sensing unit 110 may perform a role of receiving a touch input by a user. In addition, a plurality of electrodes may be provided to sense a change in capacitance due to the touch.

The touch control unit 120 controls the touch sensing unit 110, and by sensing a change in capacitance using a sensing signal output from the touch sensing unit 110, whether a touch event occurs, location, size, intensity, etc. can be detected.

That is, the touch sensor 100 composed of the above-described touch sensing unit 110 and touch control unit 120 may operate as a capacitive touch sensor.

The touch sensing unit 110 and the touch control unit 120 may be formed on one substrate or may be electrically connected after being formed on different substrates.

Referring to FIG. 2 , the touch sensing unit 110 may include a plurality of touch electrodes Tx and Rx.

For example, the touch electrodes Tx and Rx include a plurality of driving electrodes (or, referred to as transmitting electrodes, Tx1 to Txj) and a plurality of sensing electrodes (or, referred to as receiving electrodes, Rx1 to Rxk). can do.

The driving electrodes Tx1 to Txj may be elongated in a first direction (eg, X-axis direction) and arranged in plurality along a second direction (eg, Y-axis direction) intersecting the first direction. have.

The sensing electrodes Rx1 to Rxk may be elongated in the second direction (eg, the Y-axis direction) and arranged in plurality along the first direction (eg, the X-axis direction).

The driving electrodes Tx1 to Txj and the sensing electrodes Rx1 to Rxk are positioned to cross each other, thereby operating as a capacitive touch sensor.

The intersection of the driving electrodes Tx1 to Txj and the sensing electrodes Rx1 to Rxk may form a plurality of sensing nodes, and when a touch event occurs in the touch sensor 100 , a position associated with the touch event (sensing node) ) will change the mutual capacitance. A touch position may be detected by detecting a change in capacitance of the sensing node.

For example, a plurality of sensing nodes including j rows and k columns may be formed through j driving electrodes Tx1 to Txj and k sensing electrodes Rx1 to Rxk that are intersected with each other.

Each of the driving electrodes Tx1 to Txj includes a plurality of first touch sensing cells 211 arranged at a predetermined interval along a first direction (eg, an X-axis direction), and the first touch sensing cell It may include a plurality of first connection patterns 212 that electrically connect the elements 211 to each other.

In addition, each of the sensing electrodes Rx1 to Rxk includes a plurality of second touch sensing cells 221 arranged at a predetermined interval along the second direction (eg, the Y-axis direction), and the second touch It may include a plurality of second connection patterns 222 that electrically connect the sensing cells 221 to each other.

In this case, the second touch sensing cells 221 may be dispersedly disposed between the first touch sensing cells 211 so as not to overlap the first touch sensing cells 211 .

2 illustrates a case in which the first touch sensing cells 211 and the second touch sensing cells 221 have a polygonal shape, but the first touch sensing cells 211 and the second touch sensing cells ( 221) may be variously changed.

The driving electrodes Tx1 to Txj and the sensing electrodes Rx1 to Rxk may include a conductive material. For example, it may include a metal or an alloy thereof. Examples of the metal include gold (Au), silver (Ag), aluminum (Al), molybdenum (Mo), chromium (Cr), titanium (Ti), nickel (Ni), neodymium (Nd), copper (Cu), and platinum. (Pt) etc. are mentioned.

In addition, the driving electrodes Tx1 to Txj and the sensing electrodes Rx1 to Rxk may be formed of a transparent conductive material. Examples of the transparent conductive material include silver nanowires (AgNW), indium tin oxide (ITO), indium zinc oxide (IZO), antimony zinc oxide (AZO), indium tin zinc oxide (ITZO), zinc oxide (ZnO), and SnO2 ( tin oxide), carbon nanotubes, graphene, and the like. Each of the driving electrodes Tx1 to Txj and the sensing electrodes Rx1 to Rxk may be formed of a single layer or a multilayer. The driving electrodes Tx1 to Txj and the sensing electrodes Rx1 to Rxk may be made of the same material or different materials.

The driving electrodes Tx1 to Txj and the sensing electrodes Rx1 to Rxk may be disposed on a substrate (not shown). Such a substrate may be implemented as a separate substrate, and when the touch sensor 100 is included in the display device, it may be implemented as various components included in the display device. For example, the substrate may be a display panel included in the display device.

Next, the touch control unit 120 may include a touch driving unit 121 , a capacitance sensing unit 122 , and a signal processing unit 123 .

The touch driving unit 121 may supply a touch driving signal Td to the touch sensing unit 110 to drive the touch sensor 100 .

For example, the touch driving unit 121 may sequentially supply the touch driving signal Td from the first driving electrode Tx1 to the j-th driving electrode Txj. However, the present invention is not limited thereto, and the touch driving unit 121 may time-divisionally supply the touch driving signal Td according to a different order, and may also supply the touch driving signal Td to the plurality of driving electrodes according to the characteristics of the touch driving signal Td. A simultaneous supply method can also be used.

In addition, the touch driver 121 may have a frequency hopping function in order to avoid interference caused by external noise. That is, the touch driving unit 121 may change the frequency of the touch driving signal Td in response to a control signal supplied from the outside.

For example, the touch driving unit 121 may supply the touch driving signal Td of a first frequency (eg, 150 kHz), and when it is necessary to change the driving frequency in response to external noise, a second frequency different from the first frequency A touch driving signal Td having a frequency (eg, 300 kHz) may be supplied.

Also, the touch driving unit 121 may supply a demodulation signal Dm for a demodulation operation of the capacitive sensing unit 122 to the capacitance sensing unit 122 . For example, the demodulated signal Dm may include a first demodulated signal having the same phase as the touch driving signal Td and a second demodulated signal having a phase difference of 90 degrees from the touch driving signal Td.

The capacitance sensing unit 122 may be electrically connected to the sensing electrodes Rx1 to Rxk, and may receive sensing signals from the sensing electrodes Rx1 to Rxk. In addition, capacitances C1 to Ck for each channel corresponding to the received sensing signals may be calculated and output. In this case, the capacitance sensing unit 122 may demodulate the sensing signals received by using the demodulation signal Dm transmitted from the touch driving unit 121 , thereby calculating the capacitance corresponding to the sensing signal. have.

The signal processing unit 123 performs a predetermined logic operation based on the capacitances C1 to Ck for each channel received from the capacitance detection unit 122, thereby performing a touch operation on the touch sensor 100 (touch event). occurred), the location where the touch operation was performed, and its strength, etc. can be determined. Also, the signal processing unit 123 may perform a control operation on the touch driving unit 121 and/or the capacitance sensing unit 122 .

3 is a diagram illustrating in more detail the configuration of a capacitance sensing unit and a touch driving unit according to an embodiment of the present invention, and FIGS. 4A and 4B are diagrams illustrating I/Q signals according to an embodiment of the present invention.

In particular, FIGS. 4A and 4B show a case in which an offset in a non-touch state is canceled. In FIG. 4A, I/ when a touch driving signal Td of 150 kHz is used. A Q signal is shown, and FIG. 4B shows an I/Q signal when a touch driving signal Td of 300 kHz is used.

Referring to FIG. 3 , the capacitance sensing unit 122 according to the embodiment of the present invention may include a multiplexer 210 , an amplifier 220 , a mixer circuit unit 230 , and a signal magnitude calculation unit 250 . can

The multiplexer 210 is connected to the sensing electrodes Rx1 to Rxk of the touch sensing unit 110, and any one of the sensing electrodes Rx1 to Rxk (eg, the i-th sensing electrode 1≤ i≤k)), the sensing signal may be transmitted to the amplifier 220 .

In FIG. 3 , one capacitance sensing unit 122 connected to the sensing electrodes Rx1 to Rxk through the multiplexer 210 is illustrated as an example, but the present invention is not limited thereto.

If necessary, a plurality of capacitive sensing units 122 may be installed, and when the multiplexer 210 is omitted, the capacitive sensing units 122 may be installed for each channel.

The amplifier 220 may be connected to the multiplexer 210 to receive a sensing signal of a sensing electrode selected by the multiplexer 210 . For example, the sensing signal of the ith sensing electrode Ri may be input to the amplifier 220 through the multiplexer 210 .

The mixer circuit unit 230 is connected to the amplifier 220, and demodulates the output signal of the amplifier 220 into an in-phase signal (I) and a quadrature signal (Q) to calculate a signal level. (250) can be output.

To this end, the mixer circuit unit 230 receives a first demodulated signal Dm1 having the same phase as the touch driving signal Td and a second demodulated signal Dm2 having a phase difference of 90 degrees from the touch driving signal Td, A demodulation operation may be performed using the first demodulated signal Dm1 and the second demodulated signal Dm2.

For example, the mixer circuit unit 230 may include a first mixer 231 , a first analog-to-digital converter 241 , a second mixer 232 , and a second analog-to-digital converter 242 .

The first mixer 231 may mix the output signal of the amplifier 220 with the first demodulated signal Dm1 to output the in-phase signal I.

The first analog-to-digital converter 241 may be connected to the first mixer 231 to convert the in-phase signal I output from the first mixer 231 into a digital signal and output the converted signal.

The second mixer 232 may output the quadrature signal Q by mixing the output signal of the amplifier 220 with the second demodulated signal Dm2.

The second analog-to-digital converter 242 may be connected to the second mixer 232 to convert the quadrature signal Q output from the second mixer 232 into a digital signal and output it.

The signal magnitude calculation unit 250 receives the in-phase signal (I) and the quadrature signal (Q) from the mixer circuit unit 230, and the I composed of the in-phase signal (I) and the quadrature signal (Q). It is possible to calculate the magnitude (T) of the /Q (In-phase/Quadrature) signal.

The magnitude (T) of the generated I/Q signal is not affected by the signal delay of the touch sensor 100 according to the driving frequency.

Also, the signal magnitude calculator 250 may output the calculated magnitude T of the I/Q signal as a capacitance C corresponding to the detection signal of a specific detection electrode.

For example, when the i-th sensing electrode Ri is selected through the multiplexer 210 , the capacitance Ci corresponding to the sensing signal of the i-th sensing electrode Ri may be output to the signal processing unit 123 . .

The signal magnitude calculator 250 may use a COordinate Rotation Digital Computer (CORDIC) algorithm when calculating the magnitude T of an I/Q signal that is a complex signal. However, the present invention is not limited thereto, and various algorithms capable of calculating the magnitude of the complex signal may be employed.

The signal processing unit 123 may receive the capacitances C1 to Ck for each channel from the signal magnitude calculation unit 250 , and may find out the location and intensity of the touch event through this.

Meanwhile, the touch driver 121 may include a signal generator 310 , a buffer circuit 320 , and a demultiplexer 330 .

The signal generator 310 may generate a touch driving signal Td having a specific frequency and supply it to the demultiplexer 330 through the buffer circuit 320 .

The demultiplexer 330 is connected to the driving electrodes Tx1 to Txj of the touch sensing unit 110 , and selects at least one driving electrode to supply the touch driving signal Td.

In this case, the signal generator 310 may change the frequency of the touch driving signal Td and may supply the first demodulated signal Dm1 and the second demodulated signal Dm2 to the mixer circuit unit 230 . The first demodulated signal Dm1 may be set to the same signal as the touch driving signal Td, and the second demodulated signal Dm2 may be set to a signal having a phase difference of 90 degrees from the touch driving signal Td. To generate the second demodulated signal Dm2 , the signal generator 310 may include a separate phase shifter.

5 is a diagram illustrating an I/Q signal when a normal touch and an abnormal touch occur together according to an embodiment of the present invention, and FIG. 6 is an I/Q signal obtained by adding an offset value according to an embodiment of the present invention. the drawing shown.

In a specific environment, a normal touch (A) by a user and an abnormal touch (B) caused by water droplets or the like may occur together. In this case, the normal touch A is a touch by a user's finger or the like related to the ground, and an I/Q signal related thereto may be located in the first quadrant of FIG. 5 . Also, the abnormal touch B is a touch caused by a water droplet in a floating state, and an I/Q signal related thereto may be located in a third quadrant opposite to the first quadrant.

Since these two I/Q signals have the same size, it is impossible to distinguish between the normal touch A and the abnormal touch B only through size calculation.

That is, the direction of capacitance change cannot be known only by the magnitude of the I/Q signal, and even if the magnitudes of the two I/Q signals are different, if the direction of capacitance change cannot be known, the two touches cannot be distinguished.

Accordingly, the signal magnitude calculator 250 may calculate the magnitude of the I/Q signal after adding a preset offset value (Voffset) to the I/Q signal transmitted from the mixer circuit part 230 .

That is, if the size of each I/Q signal is calculated after adding the offset value Voffset to the two I/Q signals as shown in FIG. 6 , the sizes are different, so the normal touch A and the abnormal touch The distinction of (B) becomes possible.

Meanwhile, the signal magnitude calculator 250 may change the offset value Voffset in response to a change in the frequency of the touch driving signal Td. That is, as described with reference to FIGS. 4A and 4B , the direction of the I/Q signal may vary according to the magnitude of the driving frequency. Accordingly, a plurality of offset values Voffset may be preset for each frequency of the touch driving signal Td and stored in a predetermined memory (not shown).

Also, the offset value Voffset may include an offset value added to the in-phase signal I among the I/Q signals and an offset value added to the quadrature signal Q among the I/Q signals.

7 is a diagram illustrating an I/Q signal in a state in which an offset value is added according to another embodiment of the present invention. In particular, FIG. 7 illustrates a case where the direction of the offset value Voffset does not coincide with the direction of the I/Q signal.

In this case, signal loss occurs according to the angle θ between the offset value Voffset and the direction of the I/Q signal.

At this time, when the magnitude of the offset value (Voffset) is E, the magnitude of the I/Q signal is F, and the angle between the offset value (Voffset) and the direction of the I/Q signal is θ, the signal ratio thus obtained is as follows. can be derived.

Referring to FIG. 8 , the capacitance sensing unit 122 ′ according to another embodiment of the present invention includes a multiplexer 210 , an amplifier 220 , a mixer circuit unit 230 ′, and a signal level calculation unit 250 . can do.

In the embodiment related to FIG. 3 described above, the capacitance sensing unit 122 performs a demodulation operation in the analog domain through the mixer circuit unit 230, but in this embodiment related to FIG. 8, the capacitance sensing unit ( There is a difference in that the 122' performs a demodulation operation in the digital domain through the mixer circuit unit 230'.

Therefore, the description will be conducted focusing on the mixer circuit unit 230', which is a component changed from the previous embodiment.

The mixer circuit unit 230' is connected to the amplifier 220, and demodulates the output signal of the amplifier 220 into an in-phase signal (I) and a quadrature signal (Q) to calculate a signal level. output to the unit 250 .

To this end, the mixer circuit unit 230' is supplied with a first demodulated signal Dm1 having the same phase as the touch driving signal Td and a second demodulated signal Dm2 having a phase difference of 90 degrees from the touch driving signal Td. , a demodulation operation may be performed using the first demodulated signal Dm1 and the second demodulated signal Dm2.

For example, the mixer circuit unit 230 ′ may include an analog-to-digital converter 245 , a first multiplier 235 , and a second multiplier 236 .

The analog-to-digital converter 245 may convert the output signal of the amplifier 220 into a digital signal.

The first multiplier 235 may demodulate the signal output from the analog-to-digital converter 245 into an in-phase signal I using the first demodulated signal Dm1.

The second multiplier 236 may demodulate the signal output from the analog-to-digital converter 245 into a quadrature signal Q using the second demodulated signal Dm2.

The in-phase signal (I) and the quadrature signal (Q) demodulated by the mixer circuit unit 230 ′ are supplied to the signal magnitude calculation unit 250 , and the signal magnitude calculation unit 250 generates the in-phase signal (I). and a magnitude T of an in-phase/quadrature (I/Q) signal composed of a quadrature signal Q may be calculated.

9 is a flowchart illustrating a method of driving a touch sensor according to an embodiment of the present invention. A method of driving a touch sensor according to an embodiment of the present invention will be described with reference to FIGS. 1 to 8 and FIG. 9 mentioned above.

Referring to FIG. 9 , a method of driving a touch sensor according to an embodiment of the present invention includes a first frequency driving step ( S10 ), a first sensing signal amplification step ( S20 ), a first demodulation step ( S30 ), and a first capacitance It may include an output step ( S40 ), a second frequency driving step ( S50 ), a second detection signal amplification step ( S60 ), a second demodulation step ( S70 ), and a second capacitance output step ( S80 ).

In the first frequency driving step S10 , the touch driving signal Td of the first frequency may be supplied to the driving electrodes Tx1 to Txj.

In the first sensing signal amplification step S20 , the first sensing signal from the i-th sensing electrode Rxi, 1≤i≤k among the sensing electrodes Rx1 to Rxk intersecting the driving electrodes Tx1 to Txj may be input to the amplifier 220 of the capacitance sensing units 122 and 122'.

In the first demodulation step S30 , the output signal of the amplifier 220 may be demodulated into a first in-phase signal I1 and a first quadrature signal Q1 . In this case, in the first demodulation step S30 , the first demodulation signal Dm1 having the same phase as the touch driving signal Td and the second demodulating signal Dm2 having a phase difference of 90 degrees from the touch driving signal Td are used. A demodulation operation may be performed.

In the first capacitance output step S40, a predetermined first offset value Voffset1 is added to the first I/Q signal composed of the first in-phase signal I1 and the first quadrature signal Q1 to obtain the first capacitance. The magnitude of one I/Q signal may be calculated, and the calculated magnitude of the first I/Q signal may be output as a capacitance corresponding to the first detection signal.

In the second frequency driving step S50 , the touch driving signal Td having a second frequency different from the first frequency may be supplied to the driving electrodes Tx1 to Txj.

In the second sensing signal amplification step S60 , the second sensing signal from the i-th sensing electrode Rxi may be input to the amplifier 220 of the

capacitance sensing units

122 and 122 ′.

In the second demodulation step S70 , the output signal of the amplifier 220 may be demodulated into a second in-phase signal I2 and a second quadrature signal Q2 . In this case, in the second demodulation step S70 , the first demodulated signal Dm1 having the same phase as the touch driving signal Td and the second demodulating signal Dm2 having a phase difference of 90 degrees from the touch driving signal Td are used. A demodulation operation may be performed.

In the second capacitance output step S80, a predetermined second offset value Voffset2 is added to the second I/Q signal composed of the second in-phase signal I2 and the second quadrature signal Q2 to obtain the second capacitance. The magnitude of the 2 I/Q signals may be calculated, and the calculated magnitude of the second I/Q signal may be output as a capacitance corresponding to the second sensing signal.

In this case, the first offset value Voffset1 and the second offset value Voffset2 may be set to different values corresponding to the driving frequency.

Those of ordinary skill in the art to which the present invention pertains will understand that the present invention may be embodied in other specific forms without changing the technical spirit or essential features thereof. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims described later rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention. should be interpreted

Claims

a touch sensing unit including driving electrodes and sensing electrodes that cross each other;

a touch driver supplying a touch driving signal to the driving electrodes; and

a capacitance sensing unit receiving a sensing signal from an i-th sensing electrode among the sensing electrodes and outputting a capacitance corresponding to the sensing signal; including,

The capacitive sensing unit,

an amplifier receiving the sensing signal of the i-th sensing electrode;

a mixer circuit unit for demodulating the output signal of the amplifier into an in-phase signal and a quadrature signal; and

Calculating the magnitude of an I/Q signal composed of the in-phase signal and the quadrature signal, and outputting the calculated magnitude of the I/Q signal as a capacitance corresponding to the sensing signal of the i-th sensing electrode. wealth; A touch sensor comprising a.
According to claim 1,

The signal magnitude calculator,

A touch sensor, characterized in that for calculating the magnitude of the I/Q signal by adding a preset offset value to the I/Q signal.
3. The method of claim 2,

The mixer circuit unit,

A first demodulated signal having the same phase as the touch driving signal and a second demodulated signal having a phase difference of 90 degrees from the touch driving signal are supplied, and the demodulation operation is performed using the first demodulated signal and the second demodulated signal. A touch sensor, characterized in that.
3. The method of claim 2,

The touch driver,

Touch sensor, characterized in that for changing the frequency of the touch driving signal.
5. The method of claim 4,

The signal magnitude calculator,

The touch sensor, characterized in that the offset value is changed in response to a change in the frequency of the touch driving signal.
3. The method of claim 2,

The offset value is

A touch sensor comprising an offset value added to the in-phase signal and an offset value added to the quadrature signal.
4. The method of claim 3,

The mixer circuit unit,

a first mixer for mixing the output signal of the amplifier with the first demodulated signal to output the in-phase signal;

a first analog-to-digital converter for converting the in-phase signal into a digital signal and outputting it;

a second mixer for mixing the output signal of the amplifier with the second demodulated signal to output the quadrature signal; and

a second analog-to-digital converter converting the quadrature signal into a digital signal and outputting it; A touch sensor comprising a.
4. The method of claim 3,

The mixer circuit unit,

an analog-to-digital converter converting the output signal of the amplifier into a digital signal;

a first multiplier for demodulating the signal output from the analog-to-digital converter into the in-phase signal using the first demodulated signal; and

a second multiplier for demodulating the signal output from the analog-to-digital converter into the quadrature signal using the second demodulated signal; A touch sensor comprising a.
supplying a touch driving signal of a first frequency to the driving electrodes;

inputting a first sensing signal from an i-th sensing electrode among sensing electrodes crossing the driving electrodes to an amplifier;

demodulating the output signal of the amplifier into a first in-phase signal and a first quadrature signal;

The magnitude of the first I/Q signal is calculated by adding a preset first offset value to a first I/Q signal including the first in-phase signal and the first quadrature signal, and the calculated first I/Q signal is calculated. outputting the magnitude of the Q signal as a capacitance corresponding to the first detection signal;

supplying a touch driving signal of a second frequency different from the first frequency to the driving electrodes;

inputting a second sensing signal from the i-th sensing electrode to the amplifier;

demodulating the output signal of the amplifier into a second in-phase signal and a second quadrature signal; and

The magnitude of the second I/Q signal is calculated by adding a preset second offset value to a second I/Q signal composed of the second in-phase signal and the second quadrature signal, and the calculated second I/Q signal is calculated. outputting the magnitude of the Q signal as a capacitance corresponding to the second detection signal; including,

The second offset value is

The driving method of the touch sensor, characterized in that different from the first offset value.
10. The method of claim 9,

demodulating the output signal of the amplifier into a first in-phase signal and a first quadrature signal, and demodulating the output signal of the amplifier into a second in-phase signal and a second quadrature signal step is,

A method of driving a touch sensor, characterized in that the demodulation operation is performed using a first demodulated signal having the same phase as the touch driving signal and a second demodulated signal having a phase difference of 90 degrees from the touch driving signal.