Touch sensing device and method for multi-drive

Abstract

The present invention provides a touch sensing device and method for multi-driving, in which the touch sensing device reduces touch driving time and lowers signal-to-noise ratio (SNR) by using multi-driving of driving signals that can be distinguished from each other in frequency and code.

Description

Technical Field

[0001] This invention relates to a technology for sensing touch. Background Technology

[0002] Position sensors are commonly used as input devices in computers, PDAs (Personal Digital Assistants), media players, video game players, home appliances, cordless phones, public telephones, POS (point-of-sale) terminals, and ATMs. A common type of position sensor used in such applications is the touchpad sensor, readily found in input devices such as those in laptop computers. Users typically operate the touchpad sensor by moving their finger, stylus, or other stimulating object around its sensing area. Because the stimulating object generates capacitive, inductive, or other electrical effects in the carrier signal applied to the detection area, the position of the stimulating object within the detection area or its approach to the detection area can be detected using this carrier signal. The positional information detected by the touchpad sensor can be used to move a cursor or other indicator on a display screen, scroll content on a screen, or for other user interface purposes.

[0003] Although touchpad sensors have been used for many years, engineers continue to seek designs that allow for reduced production costs and improved performance. A primary focus of recent designer interest is reducing the impact of noise from the display, power supply, radio frequency interference, and / or other external sources. Noise reduction techniques, such as various types of sampling, filtering, signal processing, and shielding, have been successfully implemented to varying degrees.

[0004] On the other hand, multi-drive has been used to improve the signal-to-noise ratio (SNR), however, traditional multi-drive methods have limitations in reducing touch drive time. Summary of the Invention

[0005] In this context, one aspect of the present invention is to provide a technique for multiple drives that allows for reduced touch driving time. Another aspect of the present invention is to provide a technique for multiple drives that allows for further improvement in SNR (Spot Reduction Rate).

[0006] Therefore, in one aspect, the present invention provides a touch sensing device, comprising: a driving circuit for supplying a plurality of first frequency driving signals having a first frequency and respectively representing different codes and a plurality of second frequency driving signals having a second frequency and respectively representing different codes to a transmitting electrode; a receiving circuit for receiving a response signal from a receiving electrode coupled to the transmitting electrode via a capacitor; and a processing circuit for obtaining a first frequency element corresponding to the first frequency and a second frequency element corresponding to the second frequency from the response signal, and decoding the first frequency element and the second frequency element to generate raw touch data for the intersection of the transmitting electrode and the receiving electrode.

[0007] The first frequency and the second frequency may be orthogonal to each other, and the plurality of first frequency drive signals may include codes that are orthogonal to each other.

[0008] The processing circuit can extract the first frequency element and the second frequency element from the signal obtained by subtracting the basic response signal from the response signal, wherein the basic response signal may correspond to the signal formed in the receiving electrode in the absence of the proximity or touch of an external object.

[0009] The basic response signal may be generated according to a pattern pre-stored in the memory.

[0010] The basic response signal may be generated by converting the data of the pattern stored in the memory into an analog signal and adjusting the gain or offset of the analog signal.

[0011] The processing circuit can use Fast Fourier Transform (FFT) to obtain the first frequency element and the second frequency element.

[0012] The code matrix represented by the first frequency driving signal can be the same as the code matrix represented by the second frequency driving signal.

[0013] The code matrix can be a perfect code matrix.

[0014] The driving circuit may include a switching circuit for selectively outputting a high driving voltage or a low driving voltage, and a driving control circuit for supplying a driving control signal to the switching circuit, and generating the first frequency driving signal and the second frequency driving signal by controlling the switching circuit according to the driving control signal.

[0015] The driving circuit can use an XOR logic element to generate the first frequency driving signal and the second frequency driving signal, wherein a square wave with a specific frequency is input to one input terminal of the XOR logic element, and a code value or an inverted code value is input to the other terminal of the XOR logic element.

[0016] In another aspect, the present invention provides a method for sensing touch, comprising: supplying a plurality of first frequency drive signals having a first frequency and each representing a different code, and a plurality of second frequency drive signals having a second frequency and each representing a different code, to a transmitting electrode; receiving a response signal to the plurality of first frequency drive signals and the plurality of second frequency drive signals from a receiving electrode coupled to the transmitting electrode via a capacitor; obtaining a first frequency element corresponding to the first frequency and a second frequency element corresponding to the second frequency from the response signal; decoding the first frequency element and the second frequency element to generate raw touch data for the intersection of the transmitting electrode and the receiving electrode; and analyzing the raw touch data to generate touch data including touch coordinates.

[0017] When obtaining the first frequency element and the second frequency element respectively, the first frequency element and the second frequency element may be extracted from a signal obtained by subtracting a basic response signal from the response signal, wherein the basic response signal may correspond to a signal formed in the receiving electrode in the absence of the proximity or touch of an external object.

[0018] In another aspect, the present invention provides a touch sensing device, comprising: a driving circuit for supplying at least one first frequency driving signal having a first frequency and at least one second frequency driving signal having a second frequency to a transmitting electrode; a receiving circuit for receiving a response signal from a receiving electrode coupled to the transmitting electrode via a capacitor; and a processing circuit for obtaining a first frequency element corresponding to the first frequency and a second frequency element corresponding to the second frequency from the response signal, using the first frequency element and the second frequency element to generate raw touch data for the intersection of the transmitting electrode and the receiving electrode, and extracting a signal corresponding to a third frequency from the response signal to identify a downlink signal from an active stylus.

[0019] The first frequency, the second frequency, and the third frequency can be orthogonal to each other.

[0020] The driving circuit can supply multiple first frequency driving signals representing different codes and multiple second frequency driving signals representing different codes to the transmitting electrode, and the processing circuit can decode the first frequency elements and the second frequency elements to generate the original touch data.

[0021] As described above, the present invention allows for further reduction of touch driving time and further improvement of SNR in touch sensing. Attached Figure Description

[0022] Figure 1 This is a structural diagram of a display device according to an embodiment;

[0023] Figure 2 This is a structural diagram of an example of a touch system according to an embodiment;

[0024] Figure 3 This is a diagram illustrating an example of data encoding and data decoding in a touch system according to an embodiment;

[0025] Figure 4 It is a graph showing the changes in sensor data based on the proximity or touch of an external object;

[0026] Figure 5 This is a diagram illustrating an example of a drive signal according to an embodiment;

[0027] Figure 6 This is a structural diagram illustrating a first example of a drive circuit according to an embodiment;

[0028] Figure 7 This is a structural diagram illustrating a second example of a drive circuit according to an embodiment;

[0029] Figure 8 This is a structural diagram of a first example of the receiving circuit and processing circuit according to an embodiment;

[0030] Figure 9 Here is an example of a time series plot of the response signal;

[0031] Figure 10 Here is an example of a frequency analysis spectrum of the response signal;

[0032] Figure 11 This is a structural diagram of a second example of the receiving circuit and processing circuit according to the embodiment;

[0033] Figure 12 This is an example of a time series plot of the response signals for each code, arranged sequentially.

[0034] Figure 13 This is an example of frequency analysis spectrum of the response signal for each code in sequence;

[0035] Figure 14 This is a flowchart of a touch sensing method according to an embodiment; and

[0036] Figure 15 This is a diagram illustrating an example of a touch system with an active stylus added. Detailed Implementation

[0037] Figure 1 This is a structural diagram of a display device according to an embodiment.

[0038] refer to Figure 1 The display device 100 may include a display panel 150, a gate driving device 160, a data driving device 170, a data processing device 180, a host 190, a touch panel 110, and a touch sensing device 120.

[0039] The data driving device 170, the gate driving device 160, and the touch sensing device 120 can drive at least one component included in the display panel 150 or the touch panel 110. The data driving device 170 can drive data lines connected to pixels on the display panel 150, and the gate driving device 160 can drive gate lines connected to pixels on the display panel 150. The touch sensing device 120 can drive touch electrodes disposed on the touch panel 110.

[0040] The data driving device 170 can supply data voltage via data lines to display images in each pixel. The data driving device 170 may include at least one data driver integrated circuit, which can be connected to a bonding pad of the display panel 150 employing tape-on-bond (TAB) or glass-on-chip (COG) bonding, the bonding pad being formed directly on or integrated into the display panel 150, depending on the application. Alternatively, the data driving device 170 may be formed using a thin-film flip-chip (COF) method.

[0041] The gate driving device 160 can supply a scan signal (scan) via a gate line to turn on / off the transistors located in each pixel. Depending on the driving method, the gate driving device 160 can, as follows: Figure 1 The gate drive device 160 can be arranged on one side of the display panel 150, or divided into two and arranged on both sides of the display panel. The gate drive device 160 may include at least one gate driver integrated circuit, which can be connected to a bonding pad of the display panel 150 employing tape-on-board (TAB) or glass-on-chip (COG) type bonding pads implemented as panel gates (GIPs), which may be directly formed on or integrated onto the display panel 150, depending on the situation. Additionally, the data drive device 170 may be formed as a thin-film flip-chip (COF) type.

[0042] The data processing device 180 can receive image data RGB from the host 190 and convert the image data into a format that the data driving device 170 can recognize. In addition, the data processing device 180 can send the converted image data RGB' to the data driving device 170.

[0043] The data processing device 180 can use control signals GCS, DCS, and TCS to control the timing of the drive devices 160, 170, and 120. From this perspective, the data processing device 180 can be referred to as a timing controller.

[0044] Touch electrodes may be arranged on the touch panel 110. The touch electrodes may include transmitting electrodes and receiving electrodes. The touch sensing device 120 may send a drive signal TXS to the transmitting electrode and receive a response signal RXS from the receiving electrode to generate touch data TDATA. The touch sensing device 120 may send the touch data TDATA to the host 190. The transmitting and receiving electrodes may be the same or different. Although embodiments in which the transmitting and receiving electrodes are different and capacitively coupled will be described below, the invention is not limited thereto.

[0045] The touch sensing device 120 may include a driving circuit 122, a receiving circuit 124, a control circuit 126, and a processing circuit 128. The driving circuit 122 may send a driving signal TXS to a transmitting electrode, and the receiving circuit 124 may receive a response signal RXS from a receiving electrode. The control circuit 126 may send a timing signal to the driving circuit 122 and the receiving circuit 124. The processing circuit 128 may analyze the response signal RXS to generate touch data TDATA.

[0046] The touch sensing device 120 can form a touch system together with the touch panel 110.

[0047] Figure 2 This is a structural diagram of an example of a touch system according to an embodiment.

[0048] refer to Figure 2 On the touch panel 210, a transmitting electrode TXE and a receiving electrode RXE can be arranged. The transmitting electrode TXE and the receiving electrode RXE can be arranged along the horizontal and vertical directions, respectively, so as to intersect each other. The touch panel 210 can have a quadrilateral shape as a whole, but the present invention is not limited thereto.

[0049] The driving circuit 122 can supply a driving signal TXS to the transmitting electrode TXE. The receiving circuit 124 can receive a response signal RXS from the receiving electrode RXE and demodulate the response signal RXS to generate touch data TDATA. The transmitting electrode TXE and the receiving electrode RXE can be coupled to each other by a capacitor, and the driving signal TXS supplied to the transmitting electrode TXE can induce a response signal RXS from the receiving electrode RXE through the coupling capacitor.

[0050] The driving circuit 122 can drive multiple transmitting electrodes TXE. Here, "multiple driving" can mean driving multiple transmitting electrodes TXE simultaneously. When the touch system 200 uses multiple driving, since multiple transmitting electrodes TXE can be driven simultaneously, the total touch driving time can be shortened and touch sensitivity (signal-to-noise ratio: SNR) can be improved by making the length of the driving signal TXS supplied to each transmitting electrode TXE longer.

[0051] The driving circuit 122 can divide the transmitting electrodes TXE into multiple groups and drive the transmitting electrodes TXE in groups. For example, if there are 48 transmitting electrodes TXE arranged on the touch panel 210, the driving circuit 122 can divide the transmitting electrodes TXE into 12 groups by assigning 4 transmitting electrodes TXE in each group and driving the 4 transmitting electrodes assigned in each group at the same time.

[0052] The driving circuit 122 can simultaneously transmit driving signals, each modulated into an orthogonal form, to the transmitting electrodes TXE belonging to the same group. Even if multiple driving signals TXS, modulated into an orthogonal form, overlap in a single response signal RXS, these driving signals TXS can be separated through demodulation processing. The receiving circuit 124 can separate the effect of touch on the driving signals TXS by demodulating the response signal RXS received via the receiving electrode RXE.

[0053] Here, the drive signals TXS, modulated to be orthogonal to each other, can be drive signals representing different codes. This modulation method is called code division multiplexing (CDM). Each drive signal TXS has a code that is orthogonal to each other, and when two orthogonal codes are multiplied together, the result can be 0.

[0054] The driving circuit 122 can apply time-division driving to each group. The driving circuit 122 can drive the first group more in a first time period and drive the second group more in a second time period that does not overlap with the first time period.

[0055] The drive circuit 122 can also drive two or more groups simultaneously. For example, the drive circuit 122 can drive the first group and the second group simultaneously within the same time period. Here, the code matrix represented by the drive signal applied to the first group and the code matrix represented by the drive signal applied to the second group can be the same.

[0056] To drive two or more groups simultaneously using the same code matrix, the driving circuit 122 can set the frequency of the driving signal applied to the first group to be different from the frequency of the driving signal applied to the second group. For example, the driving circuit 122 can supply multiple first-frequency driving signals, each having a first frequency and representing a different code, to the transmitting electrode in the first group, and supply multiple second-frequency driving signals, each having a second frequency different from the first frequency and representing a different code, to the transmitting electrode in the second group. Here, the first frequency and the second frequency can be orthogonal to each other.

[0057] The receiving circuit 124 and the processing circuit 128 can separate the response signals to the first group of transmitting electrodes and the response signals to the second group of transmitting electrodes from the response signal RXS through spectrum analysis. Additionally, the receiving circuit 124 and the processing circuit 128 can separate the response signals to each transmitting electrode TXE by demodulating (e.g., CDM decoding) the frequency-separated response signals.

[0058] The receiving circuit 124 may include a readout circuit 222, an analog-to-digital converter (ADC) 224, and a multiplexer (MUX) 226.

[0059] The readout circuit 222, used to convert the response signal RXS into analog form, may include circuitry such as an integrator. An analog-to-digital converter 224 can convert the output from the readout circuit 222 into sensing data. A multi-channel memory (MUX) 226 can transmit the sensing data generated in multiple channels to the processing circuit 128.

[0060] The processing circuit 128 can process the sensed data to generate touch data. For example, the processing circuit 128 can generate raw touch data for the intersection of the transmitting electrode TXE and the receiving electrode RXE by obtaining a first frequency element corresponding to a first frequency and a second frequency element corresponding to a second frequency from the response signal RXS, and decoding the first and second frequency elements. Alternatively, the processing circuit 128 can generate touch data including touch coordinates by analyzing the raw touch data.

[0061] The control circuit 126 can send timing signals to the drive circuit 122, the receiving circuit 124, and the processing circuit 128. The drive circuit 122 and the receiving circuit 124 can send drive signals TXS and receive response signals RXS respectively according to the timing signals.

[0062] The touch system 200 can use code division multiplexing (CDM) technology as an example of multi-drive.

[0063] The driving circuit 122 can generate driving signals TXS according to the code matrix satisfying the CDM, and send these driving signals TXS to the respective transmitting electrodes TXE. The receiving circuit 124 (specifically the processing circuit 128) can generate raw touch data by applying a demodulation matrix to the sensing data generated according to the response signal RXS. Such processing in the driving circuit 122 is also referred to as data encoding, and the processing in the receiving circuit 124 is also referred to as data decoding.

[0064] Figure 3 This is an example of data encoding and data decoding in a touch system according to an embodiment.

[0065] Each driving signal TXSa~TXSd can be divided into N sequences. N is a natural number, and... Figure 3 In the example, it is 4. The drive signals TXSa to TXSd can each have a specific code value in each sequence. Figure 3 In the example, the first drive signal TXSa can have a code value (+1) in the first sequence S1 and a code value (-1) in the fourth sequence S4. Each code value can be generated through phase modulation (PM), amplitude modulation (AM), frequency modulation (FM), etc. Figure 3 In the example, the code values ​​are generated through phase modulation (PM). A square wave with a phase shift of 0° is defined as (+1), and a square wave with a phase shift of 180° is defined as (-1).

[0066] refer to Figure 3 The drive signals TXSa to TXSd corresponding to the complete code are simultaneously sent to the transmitting electrodes TXEa to TXEd of the first group TXEG1. In the first sequence S1, a square wave with a phase shift of 0° indicating (+1) is sent to the first transmitting electrode TXEa, the second transmitting electrode TXEb, and the third transmitting electrode TXEc, and a square wave with a phase shift of 180° indicating (-1) is sent to the fourth transmitting electrode TXEd.

[0067] When the driving signals TXSa to TXSd sent to the transmitting electrodes TXEa to TXEd in each sequence S1 to S4 are called codes, the response signal RXS of the receiving electrode RXE, which is coupled to the transmitting electrodes TXEa to TXEd through capacitors, or the sensing data of the response signal RXS, can be represented as the sum of the coupling capacitors C1 to C4 to which the code is applied.

[0068] For example, the sensing data S1 of the response signal RXS in the first sequence S1 can be represented as (+1)C1+(+1)C2+(+1)C3+(-1)C4.

[0069] When expressed in general terms, the sensing data Si in the i-th sequence can be represented as Equation 1.

[0070] [Equation 1]

[0071] S i =M i,1 C1+M i,1 C2+…+M i,1 C L

[0072] Here, i is a natural number, and L is a natural number representing the number of drive signals used in the multi-drive operation. The code matrix transmitted to the transmitting electrodes TXE1–TXE4 in all sequences S1–S4 can be called the code matrix M, and each code can be represented as M. i,j Here, j indicates the order of one of the drive signals in a multi-drive configuration.

[0073] The receiving circuit can receive the response signals of all sequences S1 to S4, store these response signals as sensing data, and generate demodulated data by applying the inverse matrix of the code matrix M as the demodulation matrix to the sensing data.

[0074] When expressed as a general equation, it can be represented as Equation 2.

[0075] [Equation 2]

[0076] [M][C] = [S]

[0077] [S][M] T =D

[0078] Here, M is the modulation matrix, S is the sensing data, C is the coupling capacitor, and D is the demodulated data.

[0079] An example of the complete code using the four transmit electrodes TXEa to TXEd is shown below.

[0080] [Equation 3]

[0081]

[0082]

[0083] When an external object approaches or touches the touch panel, the magnitude of the coupling capacitance changes. The touch sensing device detects this change in the magnitude of the coupling capacitance and generates touch data indicating the approach or touch of the external object.

[0084] Figure 4 It is a graph showing the changes in sensor data based on the proximity or touch of an external object.

[0085] The readout circuit of a touch sensing device converts changes in the coupling capacitance into an analog signal and outputs this signal to an analog-to-digital converter (ADC). Here, the readout circuit is typically designed so that, in the absence of an external object approaching or touching the device, the output is the median of a series of values ​​input to the ADC. For example... Figure 4 As shown, this design allows for efficient conversion of the increase or decrease of coupling capacitance in an analog-to-digital converter without saturation.

[0086] The sensing data Si in the i-th sequence, which reflects the change in the magnitude of the coupling capacitance, can be represented by Equation 4.

[0087] [Equation 4]

[0088] S i =M i,1 (C1+ΔC1)+M i,1 (C2+ΔC2)+…+M i,1 (C L +ΔC L )

[0089] Using a complete 4×4 code as the code matrix, and assuming equal coupling capacitances when there is no external object approaching or touching the object, the sensing data can be represented as the right side of Equation 5, and the demodulated data can be represented as the right side of Equation 6.

[0090] [Equation 5]

[0091]

[0092] [Equation 6]

[0093]

[0094] A touch sensing device can simultaneously supply drive signals with the same code matrix to multiple groups. Here, in order to distinguish the drive signals of one group from the drive signals of another group, the touch sensing device can supply drive signals with different frequencies to each group.

[0095] Figure 5 This is a diagram illustrating an example of a drive signal according to an embodiment.

[0096] refer to Figure 5The driving signals TXS1a to TXSKn can have different frequencies in groups. For example, the driving signals TXS1a to TXS1n in the first group can have a first frequency, the driving signals TXS2a to TXS2n in the second group can have a second frequency, and the driving signals TXSKa to TXSKn in the Kth group (K is a natural number of 3 or greater) can have a Kth frequency. Here, the first frequency, the second frequency, and the Kth frequency can all be different. Furthermore, the first frequency, the second frequency, and the Kth frequency can be orthogonal.

[0097] although Figure 5 An example of a drive signal with a square waveform is shown, but the drive signal can have a sine wave or a trapezoidal waveform.

[0098] The touch sensing device can supply first frequency driving signals TXS1a to TXS1n to the transmitting electrodes TXE1a ​​to TXE2n in the first group, supply second frequency driving signals TXS2a to TXS2n to the transmitting electrodes TXE2a to TXE2n in the second group, and supply the Kth frequency driving signals TXSKa to TXSKn to the transmitting electrodes TXEKa to TXEKn in the Kth group. Here, K is a natural number of 3 or greater, and n is a natural number of 2 or greater.

[0099] The driving circuit of a touch sensing device can use switching circuits or logic circuits to generate such driving signals.

[0100] Figure 6 This is a structural diagram illustrating a first example of a drive circuit according to an embodiment.

[0101] refer to Figure 6 The driving circuit 122a may include multiple driving channels 620a, 620b and a driving control circuit 610.

[0102] Each drive channel 620a, 620b may include a switching circuit 622 and an output pad 624.

[0103] The switching circuit 622 can be connected to the high driving voltage VH and the low driving voltage VL, and can selectively output either the high driving voltage VH or the low driving voltage VL according to the driving control signals CTRA and CTRb supplied by the driving control circuit 610. The voltage output from the switching circuit 622 can form driving signals TXSa and TXSb, and the driving signals TXSa and TXSb can be supplied to the transmitting electrodes TXEa and TXEb through the output pad 624.

[0104] The drive control circuit 610 can adjust the frequencies of the drive signals TXSa and TXSb by controlling the switching frequency of the switching circuit 622 using the drive control signals CTRA and CTRb. Additionally, the drive control circuit 610 can control the code values ​​of the drive signals TXSa and TXSb by controlling the on-off sequence of the switching circuit 622.

[0105] Figure 7 This is a structural diagram illustrating a second example of a drive circuit according to an embodiment.

[0106] refer to Figure 7 The driving circuit 122b may include a square wave generation circuit 710, multiple driving channels 720a and 720b, and a T flip-flop circuit 730.

[0107] The square wave generation circuit 710 may include a counter and output a square wave having a first control frequency to the T flip-flop circuit 730. The T flip-flop circuit 730 may include a clock having a second control frequency and is connected to the square wave generation circuit 710 at its input terminal and to each of the drive channels 720a, 720b at its Q output terminal. This structure allows the T flip-flop circuit 730 to supply a square wave having a control frequency corresponding to the product of the first and second control frequencies to each of the drive channels 720a, 720b.

[0108] Here, the T flip-flop circuit 730 may include an XOR logic element and a D flip-flop circuit 732. The Q output terminal of the D flip-flop circuit 732 may be connected to one input terminal of the XOR logic element, and the output terminal of the square wave generation circuit 710 may be connected to the other input terminal of the XOR logic element.

[0109] Each drive channel 720a, 720b may include an XOR logic element. One input terminal of the XOR logic element may be connected to the Q output terminal of the T flip-flop circuit 730, and the code value cd(1,j), cd(2,j), or an inverted code value may be input through the other input terminals of the XOR logic element.

[0110] The drive circuit 122b can adjust the frequencies of the drive signals TXSa and TXSb by controlling the first control frequency and the second control frequency. Additionally, the drive circuit 122b can use the code values ​​cd(1,j) and cd(2,j) input to the XOR logic element to represent the codes of the drive signals TXSa and TXSb.

[0111] When drive signals representing different codes or having different frequencies are supplied to the transmitting electrode, the response signal may be subject to complex influences from the corresponding drive signals. The receiving and processing circuits of the touch sensing device can receive such response signals and perform spectrum analysis and signal decoding to separate the signals used for each drive signal from the response signal.

[0112] Figure 8 This is a structural diagram of a first example of a receiving circuit and a processing circuit according to an embodiment.

[0113] refer to Figure 8 The receiving circuit 124a may include a signal amplification circuit 810, a filtering circuit 820, and an analog-to-digital conversion circuit 830, and the processing circuit 128 may include a spectrum analysis circuit 850, a decoding circuit 860, and a memory 870.

[0114] The signal amplification circuit 810 can receive the response signal RXS from the receiving electrode and adjust the gain or offset of the response signal. The filter circuit 820 can receive the signal output from the signal amplification circuit 810 and remove unwanted elements from the signal. For example, the filter circuit 820 may include a low-pass filter and remove low-frequency noise from the signal output from the signal amplification circuit 810. The analog-to-digital converter circuit 830 can convert the output from the filter circuit 820 into digital data and send the digital data to the processing circuit 128.

[0115] The spectrum analysis circuit 850 can use digital data to perform frequency analysis on the response signal and obtain a first frequency element corresponding to a first frequency and a second frequency element corresponding to a second frequency from the analysis results.

[0116] Figure 9 This is an example of a time series plot of the response signal, and Figure 10 This is an example of a frequency analysis spectrum of the response signal.

[0117] exist Figure 9 and Figure 10 In the diagram, the solid line represents the curve related to the basic response signal, and the dashed line represents the curve related to the response signal when an external object approaches or touches the touch panel. Here, the basic response signal corresponds to the signal formed in the receiving electrode when no external object approaches or touches the touch panel.

[0118] refer to Figure 9 When an external object approaches or touches the touch panel, as shown by the dotted line, the magnitude of the response signal can increase. (Reference) Figure 10 When an external object approaches or touches the touch panel, as shown by the dotted line, the element value at a specific frequency can increase.

[0119] refer to Figure 8 , Figure 9 and Figure 10 The processing circuit 128 can use the element values ​​of each frequency obtained by the spectrum analysis circuit 850 to separate the response signal by frequency.

[0120] The decoding circuit 860 can decode the element values ​​of each frequency to separate the response signal by code. The data obtained by separating the response signal by frequency and code can be stored in memory as raw touch data for the intersection of the transmitting and receiving electrodes.

[0121] The processing circuit 128 can generate touch data including touch coordinates by analyzing the raw touch data, and send the touch data to the host.

[0122] On the other hand, due to such Figure 9 and Figure 10 As shown, the proximity or touch of an external object does not have a significant impact on the response signal. Therefore, the touch sensing device can generate raw touch data by extracting data only from the portion where there is a difference between the basic response signal and the response signal (i.e., the difference is due to the proximity or touch of an external object).

[0123] Figure 11 This is a structural diagram of a second example of the receiving circuit and processing circuit according to an embodiment.

[0124] refer to Figure 11 The receiving circuit 124b may include a first memory 1120, a digital-to-analog converter 1130, a signal amplification circuit 1140, a signal subtraction circuit 1110, a filter circuit 820, and an analog-to-digital conversion circuit 830, and the processing circuit 128 may include a spectrum analysis circuit 850, a decoding circuit 860, and a memory 870.

[0125] The receiving circuit 124b can use the first memory 1120, the digital-to-analog converter 1130, and the signal amplification circuit 1140 to generate the basic response signal RXSB.

[0126] The first memory 1120 can store the pattern of the basic response signal RXSB. The digital-to-analog converter 1130 can receive data related to the pattern stored in the first memory 1120 and convert the data into an analog signal. The signal amplification circuit 1140 can generate the basic response signal RXSB by adjusting the gain or offset of the analog signal.

[0127] Signal subtraction circuit 1110 generates subtracted signal RXSD by subtracting the basic response signal RXSB from the response signal RXS. Filter circuit 820 removes unnecessary elements from the subtracted signal RXSD, and analog-to-digital converter circuit 830 converts the output from filter circuit 820 into digital data and sends the digital data to processing circuit 128.

[0128] The spectrum analysis circuit 850 can use digital data to perform frequency analysis on the response signal and obtain a first frequency element corresponding to a first frequency and a second frequency element corresponding to a second frequency from the analysis results. The decoding circuit 860 can decode the element values ​​of each frequency to separate the response signal by code. The data separated by frequency and code through such processing can be stored in the second memory 870 as the original touch data for the intersection of the transmitting and receiving electrodes.

[0129] Figure 12 This is an example of a time-series plot of the response signals for each code, and... Figure 13 This is an example of a frequency analysis spectrum of the response signal for each code in sequence.

[0130] like Figure 12 and Figure 13 As shown, the touch sensing device can receive response signals from each sequence S1 to S4 and perform frequency analysis on each response signal. Furthermore, the touch sensing device can use the frequency analysis values ​​obtained for each sequence S1 to S4 to decode each response signal.

[0131] exist Figure 12 and Figure 13 In the graph, the response signal without subtracting the basic response signal is shown as a dashed line, and the subtracted signal obtained by subtracting the basic response signal from the response signal is shown as a solid line. For example... Figure 12 and Figure 13 As shown, the level of the subtracted signal is lower than the level of the response signal, and unnecessary frequency elements are removed. Therefore, sensing performance can be improved.

[0132] Figure 14 This is a flowchart of a touch sensing method according to an embodiment.

[0133] refer to Figure 14 The touch sensing device can supply a plurality of first-frequency drive signals, each having a first frequency and representing a different code, and a plurality of second-frequency drive signals, each having a second frequency and representing a different code, to the transmitting electrode (S1400). Here, the first frequency and the second frequency can be different from each other and orthogonal to each other. In addition, the codes applied to the first-frequency drive signals or the second-frequency drive signals can be orthogonal to each other and can be complete codes.

[0134] The touch sensing device can receive response signals to a plurality of first frequency drive signals and a plurality of second frequency drive signals from a receiving electrode coupled to a transmitting electrode via a capacitor (S1402).

[0135] The touch sensing device can generate a subtraction signal by subtracting the basic response signal from the response signal (S1404).

[0136] The touch sensing device can obtain the element values ​​of each frequency by performing spectral analysis on the subtracted signal (S1406). Here, the touch sensing device can perform spectral analysis on each sequence of the code.

[0137] The touch sensing device can decode the element values ​​of each frequency to obtain the raw touch data for each frequency and each code, and store the raw touch data in the memory.

[0138] The touch sensing device analyzes the raw touch data to generate touch data including touch coordinates (S1410) and sends the touch data to the host (S1412).

[0139] Figure 15 This is a diagram illustrating an example of a touch system with an active stylus added.

[0140] refer to Figure 15 In addition to the finger 10, the active stylus 20 can also be used as an external object in the touch system 1500.

[0141] The touch sensing device can supply a plurality of first frequency drive signals TXS1a and TXS1b having a first frequency and a plurality of second frequency drive signals TXS2a and TXS2b having a second frequency to the transmitting electrode TXE. The touch sensing device can receive a response signal RXS from the receiving electrode RXE, which is coupled to the transmitting electrode via a capacitor, and generate raw touch data for the intersection of the transmitting and receiving electrodes by performing frequency analysis on the response signal RXS.

[0142] On the other hand, the downlink signal from the active stylus 20 can be transmitted to the receiving electrode RXE. The active stylus 20 can also transmit a downlink signal at a third frequency, different from the first and second frequencies, to the receiving electrode RXE. Such a downlink signal may affect the response signal RXS.

[0143] The touch sensing device can obtain a first frequency element corresponding to a first frequency and a second frequency element corresponding to a second frequency from the response signal RXS by performing frequency analysis on the response signal, and use the first frequency element and the second frequency element to generate raw touch data for the intersection of the transmitting electrode and the receiving electrode.

[0144] Additionally, the touch sensing device can extract the signal corresponding to the third frequency from the response signal RXS to identify the downlink signal from the active stylus 20. Here, the touch sensing device can use a bandpass filter or other methods to extract the signal corresponding to the third frequency from the response signal RXS.

[0145] Using this method, both finger touch and active pen touch can be detected simultaneously.

[0146] Cross-references to related applications

[0147] This application claims priority to Korean Patent Application No. 10-2019-0176679, filed on December 27, 2019, the entire contents of which are incorporated herein by reference.

Claims

1. A touch sensing device, comprising: A driving circuit is used to supply a plurality of first frequency driving signals having a first frequency and representing different codes to a first group of transmitting electrodes and to supply a plurality of second frequency driving signals having a second frequency and representing different codes to a second group of transmitting electrodes. A receiving circuit is configured to receive a response signal from a receiving electrode coupled to the transmitting electrodes of the first group and the second group via a capacitor. as well as The processing circuit is configured to obtain a first frequency element corresponding to the first frequency and a second frequency element corresponding to the second frequency from the response signal, and to decode the first frequency element and the second frequency element to generate raw touch data for the intersection of the transmitting electrode and the receiving electrode. The plurality of first frequency drive signals and the plurality of second frequency drive signals are simultaneously supplied to the transmitting electrodes of the first group and the transmitting electrodes of the second group.

2. The touch sensing device according to claim 1, wherein, The first frequency and the second frequency are orthogonal to each other, and the plurality of first frequency drive signals include codes that are orthogonal to each other.

3. The touch sensing device according to claim 1, wherein, The processing circuit extracts the first frequency element and the second frequency element from the signal obtained by subtracting the basic response signal from the response signal, wherein the basic response signal corresponds to the signal formed in the receiving electrode in the absence of the proximity or touch of an external object.

4. The touch sensing device according to claim 3, wherein, The basic response signal is generated based on a pattern pre-stored in the memory.

5. The touch sensing device according to claim 4, wherein, The basic response signal is generated by converting the data of the pattern stored in the memory into an analog signal and adjusting the gain or offset of the analog signal.

6. The touch sensing device according to claim 1, wherein, The processing circuit uses Fast Fourier Transform (FFT) to obtain the first frequency element and the second frequency element.

7. The touch sensing device according to claim 1, wherein, The code matrix represented by the first frequency driving signal is the same as the code matrix represented by the second frequency driving signal.

8. The touch sensing device according to claim 7, wherein, The code matrix is ​​a complete code matrix.

9. The touch sensing device according to claim 1, wherein, The driving circuit includes a switching circuit for selectively outputting a high driving voltage or a low driving voltage, and a driving control circuit for supplying a driving control signal to the switching circuit, and generating a first frequency driving signal and a second frequency driving signal by controlling the switching circuit according to the driving control signal.

10. The touch sensing device according to claim 1, wherein, The driving circuit uses an XOR logic element to generate the first frequency driving signal and the second frequency driving signal, wherein a square wave with a specific frequency is input to one input terminal of the XOR logic element, and a code value or an inverted code value is input to the other terminal of the XOR logic element.

11. A method for sensing touch, comprising: A plurality of first-frequency drive signals having a first frequency and representing different codes are supplied to the first group of transmitting electrodes, and a plurality of second-frequency drive signals having a second frequency and representing different codes are supplied to the second group of transmitting electrodes. Response signals to the plurality of first frequency drive signals and the plurality of second frequency drive signals are received from the receiving electrodes coupled to the transmitting electrodes of the first group and the transmitting electrodes of the second group via capacitors; Obtain a first frequency element corresponding to the first frequency and a second frequency element corresponding to the second frequency from the response signal; The first frequency element and the second frequency element are decoded to generate raw touch data for the intersection of the transmitting electrode and the receiving electrode; as well as Analyze the raw touch data to generate touch data including touch coordinates. The plurality of first frequency drive signals and the plurality of second frequency drive signals are simultaneously supplied to the transmitting electrodes of the first group and the transmitting electrodes of the second group.

12. The method for sensing touch according to claim 11, wherein, The first frequency element and the second frequency element are obtained by extracting the first frequency element and the second frequency element from a signal, wherein the signal is obtained by subtracting a basic response signal from the response signal, the basic response signal corresponding to a signal formed in the receiving electrode in the absence of the proximity or touch of an external object.

13. A touch sensing device, comprising: A driving circuit is used to supply a plurality of first frequency driving signals having a first frequency and representing different codes to a first group of transmitting electrodes and to supply a plurality of second frequency driving signals having a second frequency and representing different codes to a second group of transmitting electrodes. A receiving circuit is configured to receive a response signal from a receiving electrode coupled to the transmitting electrodes of the first group and the second group via a capacitor. as well as The processing circuitry is configured to obtain a first frequency element corresponding to the first frequency and a second frequency element corresponding to the second frequency from the response signal; use the first frequency element and the second frequency element to generate raw touch data for the intersection of the transmitting electrode and the receiving electrode; and extract a signal corresponding to a third frequency from the response signal to identify a downlink signal from the active stylus. The plurality of first frequency drive signals and the plurality of second frequency drive signals are simultaneously supplied to the transmitting electrodes of the first group and the transmitting electrodes of the second group.

14. The touch sensing device according to claim 13, wherein, The first frequency, the second frequency, and the third frequency are orthogonal to each other.

15. The touch sensing device according to claim 13, wherein, The processing circuit decodes the first frequency element and the second frequency element to generate the original touch data.

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