Touch controller, touch control device, display equipment and touch detection method

Abstract

The embodiment of the invention relates to a touch controller for a touch sensor, a touch control device, display equipment and a touch detection method. The touch sensor comprises a plurality of first electrodes and a plurality of second electrodes which are arranged in a crossed mode. A touch controller detects a plurality of first electrodes or a plurality of second electrodes in pairs, the touch controller including a plurality of signal processing circuits, each signal processing circuit including a differential amplifier connected to a pair of electrodes detected in pairs among the plurality of first electrodes or the plurality of second electrodes, the differential amplifier is used for carrying out differential amplification processing on two sensing signals of the pair of electrodes, the sensing signals are generated based on an excitation signal provided by the touch controller, and the power supply voltage accessed by the differential amplifier comprises a first power supply voltage higher than the maximum voltage of the excitation signal and / or a second power supply voltage lower than the minimum voltage of the excitation signal. According to the touch controller provided by the embodiment of the invention, at least the measurement noise of the touch signal can be reduced, and the measurement sensitivity is improved.

Description

Technical Field

[0001] The present disclosure relates to a touch controller for a touch sensor, a touch control device, a display device, and a touch detection method. Background Art

[0002] With the development of electronic technology, touch display devices capable of detecting external approaching objects are widely used. For example, touch display devices are usually equipped on smart devices. A touch sensor may be provided on the touch display device. For example, a Projected Capacitive Touch (PCAP) sensor is a mainstream sensor applied to a display device or a touch control device, and can implement a mutual capacitance or self-capacitance sensing operation mode.

[0003] Reducing the measurement noise of touch signals and improving the measurement sensitivity are goals pursued by the industry. Summary of the Invention

[0004] At least one embodiment of the present disclosure provides a touch controller for a touch sensor. The touch sensor includes a plurality of first electrodes and a plurality of second electrodes arranged crosswise, and the touch controller detects the plurality of first electrodes or the plurality of second electrodes in pairs; the touch controller includes a plurality of signal processing circuits, and each signal processing circuit includes a differential amplifier connected to a pair of electrodes detected in pairs among the plurality of first electrodes or the plurality of second electrodes to perform differential amplification processing on two sensing signals of the pair of electrodes; wherein, the sensing signals are generated based on an excitation signal provided by the touch controller, and the power supply voltage accessed by the differential amplifier includes at least one of the following: a first power supply voltage and a second power supply voltage, the first power supply voltage is higher than the maximum voltage of the excitation signal, and the second power supply voltage is lower than the minimum voltage of the excitation signal.

[0005] At least one embodiment of the present disclosure provides a touch control device, which includes the touch controller provided by at least one embodiment of the present disclosure; and a touch sensor.

[0006] At least one embodiment of the present disclosure provides a display device, which includes a display screen; and the touch control device provided by at least one embodiment of the present disclosure, wherein the touch sensor is stacked with the display screen.

[0007] At least one embodiment of the present disclosure provides a touch detection method for a touch sensor, the touch sensor including a plurality of first electrodes and a plurality of second electrodes arranged crosswise; the touch detection method includes: performing differential amplification processing on two sensing signals of a pair of electrodes connected to a differential amplifier by using the differential amplifier included in a touch controller to obtain an amplified differential signal; and demodulating the amplified differential signal to obtain a touch detection result, wherein the touch controller includes a plurality of signal processing circuits, each signal processing circuit includes a differential amplifier, the differential amplifier is connected to a pair of electrodes to be detected in pairs among the plurality of first electrodes or the plurality of second electrodes; the sensing signals are generated based on an excitation signal provided by the touch controller; the power supply voltage accessed by the differential amplifier includes at least one of the following: a first power supply voltage and a second power supply voltage, the first power supply voltage is higher than the maximum voltage of the excitation signal, and the second power supply voltage is lower than the minimum voltage of the excitation signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure and do not limit the present disclosure.

[0009] Figure 1 FIG. shows a schematic diagram of an application scenario of a touch controller for a touch sensor;

[0010] Figure 2 FIG. shows a schematic diagram of the principle of a touch controller for a touch sensor measuring a touch signal;

[0011] Figure 3 FIG. shows a schematic diagram of the working principle of a touch controller provided by at least one embodiment of the present disclosure;

[0012] Figure 4 Schematically shows a schematic diagram of the working principle of a touch controller for a touch sensor according to at least another embodiment of the present disclosure;

[0013] Figure 5 FIG. shows a schematic diagram of the structure of a differential amplifier included in a touch controller in at least one embodiment of the present disclosure;

[0014] Figure 6 FIG. shows a schematic diagram of the structure of a differential amplifier included in a touch controller in at least another embodiment of the present disclosure;

[0015] Figure 7A FIG. shows a cross-sectional view of a rail-to-rail operational amplifier;

[0016] Figure 7B FIG. shows a cross-sectional view of a differential amplifier in at least one embodiment of the present disclosure;

[0017] Figure 8Shows a comparison graph of the measurement noise of multiple touch controllers;

[0018] Figure 9 Shows a schematic structural diagram of a differential front end included in a touch controller in at least one embodiment of the present disclosure;

[0019] Figure 10 Shows a schematic flowchart of a touch detection method for a touch sensor in at least one embodiment of the present disclosure;

[0020] Figure 11 Shows a structural block diagram of a touch control device provided in at least one embodiment of the present disclosure; and

[0021] Figure 12 Shows a structural block diagram of a display device provided in at least one embodiment of the present disclosure. Detailed implementation manners

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0023] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure shall have the ordinary meanings understood by those of ordinary skill in the art to which the present disclosure pertains. The "first", "second", and similar terms used in the present disclosure do not denote any order, quantity, or importance, but are only used to distinguish different components. Similarly, the terms such as "a", "an", or "the" do not denote a quantity limitation, but mean that there is at least one. The terms such as "including" or "comprising" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0024] PCAP sensors are usually made of conductive materials on the glass surface to form a horizontal electrode array and a vertical electrode array, and the horizontal electrode array and the vertical electrode array form an orthogonal grid. For example, a PCAP sensor includes multiple TX lines (i.e., vertical electrodes) and multiple RX lines (i.e., horizontal electrodes) arranged crosswise. These TX lines and RX lines are insulated from each other, and there is only a projection field between them. The touch controller for the PCAP sensor measures the mutual capacitance of the grid nodes or the self-capacitance of each layer to implement the mutual capacitance or self-capacitance sensing operation mode for the PCAP sensor.

[0025] Figure 1 FIG. shows a schematic diagram of an application scenario of a touch controller for a touch sensor.

[0026] As Figure 1 shown, in the self-capacitance sensing operation mode, a parasitic capacitance Cpx is generated between the vertical electrode (i.e., the TX electrode) and the ground, and a parasitic capacitance Cpy is generated between the horizontal electrode (i.e., the RX electrode) and the ground. In addition, a coupling capacitance Cm is also generated between two adjacent electrodes.

[0027] When the electrode is driven, a projection field is also generated between the electrode and the free space, thereby generating a capacitance Cs. When an object such as a finger approaches or touches a display device provided with a touch sensor, an additional capacitance is formed between the object and the electrode. For example, an additional capacitance Cfx is formed between the object and the vertical electrode, and an additional capacitance Cfy is formed between the object and the horizontal electrode. This additional capacitance is superimposed on the capacitance formed by the electrode and the ground, causing the total capacitance of the electrode to the ground to change. For example, the total capacitance will increase.

[0028] For example, the touch controller can measure the touch signal generated by an object approaching or touching the display device by measuring the change in the total capacitance of the electrode to the ground.

[0029] Generally, the additional capacitance formed between the object and the electrode is usually only a small part of the parasitic capacitance generated between the electrode and the ground, and the influence of the additional capacitance on the change in the total capacitance is small. For example, in order to reduce the influence of external noises such as display noise on measuring the touch signal, etc., a differential method can be used to measure the touch signal.

[0030] Figure 2 FIG. shows a schematic diagram of the principle of a touch controller measuring a touch signal.

[0031] As Figure 2 shown, in a specific application scenario 200, the touch controller 201 at least includes a driving circuit and a differential amplifier circuit. The touch sensor 202 includes multiple vertical electrodes TX and multiple horizontal electrodes RX arranged crosswise. The differential amplifier circuit can include a differential amplifier with any structure.

[0032] When measuring a touch signal in a self - capacitance sensing operation mode, a driving circuit provides excitation signals to a plurality of longitudinal electrodes TX. A differential amplification circuit is connected to a pair of electrodes among the plurality of longitudinal electrodes TX to differentially amplify the sensing signals provided by the pair of electrodes, and determines a touch detection result based on the amplified differential signal.

[0033] It can be understood that a differential signal refers to the result obtained by performing a difference operation on two signals, and the two signals can be analog signals or digital signals. In at least one embodiment of the present disclosure, the two signals are two sensing signals provided by a pair of electrodes. For example, in some embodiments, a differential signal is also referred to as a differential - mode signal. When this concept is used in a differential circuit, if the voltages of the two signals are set as V1 and V2 respectively, for the signal with voltage V1, its differential signal can be expressed as (V1 - V2) / 2, and for the signal with voltage V2, its differential signal is (V2 - V1) / 2. For example, for an ideal differential amplifier, if the voltage of its positive input signal is V1 and the voltage of its negative input signal is V2, then the voltage V out of its output signal and the relationship of the input signals can be expressed as V out =A d (V1 - V2). This output signal can be understood as the amplified differential signal, where A d is the gain coefficient of the differential amplifier.

[0034] When the differential amplification circuit is connected to a pair of electrodes among the plurality of longitudinal electrodes TX, the touch position in the horizontal direction corresponding to when an object approaches or touches the display device can be determined. When the driving circuit provides excitation signals to a plurality of horizontal electrodes RX and the differential amplification circuit is connected to a pair of electrodes among the plurality of horizontal electrodes RX, the touch position in the vertical direction corresponding to when an object approaches or touches the display device can be determined. In actual detection, it is necessary to determine the touch position in the horizontal direction and the touch position in the vertical direction to locate the touch position on the display device.

[0035] In at least one embodiment, regardless of measuring the touch position in the horizontal direction or the touch position in the vertical direction, the driving circuit can drive the horizontal electrodes RX and the longitudinal electrodes TX simultaneously to eliminate the influence of the mutual capacitance between the electrodes on the detection of the touch signal.

[0036] For example, whether the transistors included in a differential amplifier are in an operating state affects the gain of the differential amplifier. The excitation signal provided by the drive circuit is a periodic signal (such as a square wave signal), which causes the differential amplifier to be in a cut-off state at certain moments, and the gain of the differential amplifier changes, which may cause the output signal of the differential amplifier to be truncated or clipped, thereby generating AM-PM distortion (Amplitude-to-Phase Modulation Distortion). Moreover, due to the non-linearity of the differential amplifier, intermodulation products may be generated during the process of the differential amplifier amplifying the detected sensing signal. These effects cause low-frequency noise to be superimposed on the carrier, thereby contaminating the touch signal and reducing the sensitivity of touch detection.

[0037] To at least partially solve this technical problem, embodiments of the present disclosure provide a touch controller for a touch sensor. The following will be combined with Figures 3 - 9 to describe the touch controller and its working principle in detail.

[0038] Figure 3 The working principle diagram of the touch controller provided by at least one embodiment of the present disclosure is shown.

[0039] As Figure 3 shown, in this embodiment 300, the touch controller includes a plurality of signal processing circuits, and each signal processing circuit includes a differential amplifier 311. The touch sensor includes a plurality of first electrodes (which can be the aforementioned longitudinal electrodes, for example) and a plurality of second electrodes (which can be the aforementioned transverse electrodes, for example) arranged crosswise.

[0040] For example, the touch controller can provide an excitation signal Vex to a plurality of electrodes arranged in parallel in at least one direction in the first electrodes and the second electrodes, and a plurality of first electrodes or a plurality of second electrodes can be detected by the touch controller in pairs for sensing signals. When an object approaches or touches a display device including a touch sensor, there may be a difference between the two sensed signals detected in pairs.

[0041] For example, the differential amplifier 311 can be connected to a pair of electrodes (including electrode 312 and electrode 322) detected in pairs, and is used to perform differential amplification processing on the two sensed signals provided by the pair of electrodes. For example, the control terminal of the differential amplifier 311 is connected to the pair of electrodes.

[0042] For example, the differential amplifier 311 includes two transistors, and the two transistors form a differential pair tube. The control terminals of the two transistors are respectively connected to two electrodes in a pair of electrodes detected in pairs. For example, the transistors included in the differential amplifier can be field effect transistors or bipolar transistors, etc., and the present disclosure does not limit this.

[0043] In at least one embodiment of the present disclosure, the input terminals of the differential amplifier (e.g., the input terminals of two transistors) may be connected to an external power supply to access the power supply voltage provided by the external power supply. For example, the power supply voltage may be connected to a current source, and the current source provides a bias current to the differential amplifier. For example, when the control terminal of the differential amplifier 311 is connected to a pair of electrodes to be detected in pairs, when the differential amplifier uses a P-type transistor, the power supply voltage Vdd_diff accessed by the differential amplifier may be higher than the maximum voltage Vdd of the excitation signal Vex. When the differential amplifier uses an N-type transistor, the power supply voltage Vss_diff accessed by the differential amplifier may be lower than the minimum voltage Vss of the excitation signal Vex, thereby increasing the voltage range (the voltage range of the excitation signal) in which the transistor is in the operating region. In this way, the duration of the differential amplifier operating in the linear region can be increased, the AM-PM distortion caused by the change in the gain of the differential amplifier and the intermodulation products generated by nonlinearity can be reduced, the low-frequency noise superimposed on the carrier can be reduced to a certain extent, and the sensitivity of touch detection can be improved.

[0044] It can be understood that, according to actual requirements, the power supply voltage accessed by the differential amplifier may include at least one of the following: Vdd_diff (hereinafter also referred to as the first power supply voltage), Vss_diff (hereinafter also referred to as the second power supply voltage). The specific number of the accessed power supply voltages can be determined according to the structural type of the differential amplifier. The first power supply voltage is, for example, higher than the second power supply voltage. The present disclosure does not limit this. For ease of understanding, Figure 3 Both Vdd_diff and Vss_diff are shown. For example, in one embodiment, the power supply voltage accessed by the differential amplifier may include the first power supply voltage and / or the second power supply voltage. The first power supply voltage is higher than the maximum voltage Vdd of the excitation signal Vex, or the second power supply voltage is lower than the minimum voltage Vss of the excitation signal Vex.

[0045] In at least one embodiment of the present disclosure, in the mutual capacitance sensing operation mode, the excitation signal provided by the touch controller may be input to a plurality of first electrodes, and a pair of electrodes to be detected in pairs is composed of two electrodes among a plurality of second electrodes. Alternatively, the excitation signal may be input to a plurality of second electrodes, and a pair of electrodes to be detected in pairs is composed of two electrodes among a plurality of first electrodes. That is, in the mutual capacitance sensing operation mode, the excited electrode and the detected electrode are electrodes in two different directions.

[0046] In at least one embodiment of the present disclosure, in the self - capacitance sensing operation mode, the excitation signal provided by the touch controller can be input to a plurality of first electrodes and / or a plurality of second electrodes. A pair of electrodes to be detected in pairs is composed of two electrodes among the plurality of first electrodes input with the excitation signal, or composed of two electrodes among the plurality of second electrodes input with the excitation signal. That is, in the self - capacitance sensing operation mode, the excited electrode and the detected electrode are electrodes in the same direction.

[0047] It can be understood that Figure 3 only the connection relationship between the differential amplifier included in one signal processing circuit and the electrodes is shown. The connection relationship between the differential amplifier included in other signal processing circuits among the plurality of signal processing circuits and the electrodes is Figure 3 similar to the shown connection relationship, and the electrode pairs connected by the differential amplifiers included in the two signal processing circuits are different.

[0048] Figure 4 Schematically shows the working principle diagram of the touch controller for a touch sensor in at least another embodiment of the present disclosure.

[0049] As Figure 4 shown, in this embodiment, in addition to the signal processing circuit including the differential amplifier 411, the touch controller 400 further includes a driving circuit 403. The driving circuit is connected to a pair of electrodes connected by the differential amplifier 411 and other electrodes arranged in parallel with the pair of electrodes to provide an excitation signal to the connected electrodes.

[0050] For example, the third power supply voltage accessed by the driving circuit 403 is the voltage Vdd_High, the fourth power supply voltage accessed by the driving circuit 403 is the voltage Vdd_Low, and the third power supply voltage is higher than the fourth power supply voltage. In at least one embodiment of the present disclosure, the first power supply voltage accessed by the differential amplifier 411 can be higher than the voltage Vdd_High accessed by the driving circuit 403, or the second power supply voltage accessed by the differential amplifier 411 can be lower than the voltage Vdd_Low accessed by the driving circuit 403. For example, the maximum voltage of the excitation signal provided by the driving circuit can be lower than or equal to the voltage Vdd_High accessed by the driving circuit 403. For example, according to actual requirements, the minimum voltage of the excitation signal provided by the driving circuit can also be set to be higher than or equal to the low voltage Vdd_Low accessed by the driving circuit.

[0051] In at least one embodiment of the present disclosure, the touch controller may include two sets of driving circuits, namely a first driving circuit and a second driving circuit. The first driving circuit is configured to provide an excitation signal to a pair of electrodes connected to the differential amplifier 411 and other electrodes arranged in parallel with the pair of electrodes. The second driving circuit is configured to provide an excitation signal to a plurality of electrodes arranged crosswise with the pair of electrodes connected to the differential amplifier 411. The intensities of the excitation signals provided by the two sets of driving circuits may be the same or different. By simultaneously driving the first electrode and the second electrode for self-capacitance sensing, the influence of the mutual capacitance between the electrodes on the detection of the touch signal can be eliminated to a certain extent.

[0052] For example, in one embodiment, the intensities of the excitation signals provided by the two sets of driving circuits may be the same to completely eliminate the influence of the mutual capacitance between the first electrode and the second electrode on the detection of the touch signal in an ideal state.

[0053] In at least one embodiment of the present disclosure, when the power supply voltage connected to the differential amplifier is fixed, the excitation signal can be controlled by the driving circuit to adjust the voltages of the two sensing signals of a pair of electrodes connected to the differential amplifier. For example, by controlling the swing of the excitation signal, it can be better ensured that the first power supply voltage connected to the differential amplifier is higher than the maximum voltage of the excitation signal, and / or the second power supply voltage connected to the differential amplifier is lower than the minimum voltage of the excitation signal. Therefore, the duration of the differential amplifier operating in the linear region can be increased to a certain extent.

[0054] Figure 5 The structural schematic diagram of the differential amplifier included in the touch controller in at least one embodiment of the present disclosure is shown.

[0055] As Figure 5 shown, in an embodiment 500, the differential amplifier 511 may include a first differential pair of transistors formed by two P-type transistors. The first differential pair of transistors is connected to the first power supply voltage. For example, the two P-type transistors may include transistor MP1 and transistor MP2. The two P-type transistors may be field effect transistors, for example, P-channel metal oxide semiconductor field effect transistors, or other types of P-type transistors. The embodiments of the present disclosure do not limit this.

[0056] For example, the control terminals of the two P-type transistors in the first differential pair of transistors are respectively connected to two electrodes in a pair of electrodes to be detected in pairs. For example, the input voltages of the control terminals of the two P-type transistors are voltage Vin1 and voltage Vin2 respectively. The input terminals of the two P-type transistors are respectively connected to the first power supply voltage Vdd_diff. According to actual requirements, the input of the input terminals of the two P-type transistors may be the bias current provided by a current source Ip including the first power supply voltage Vdd_diff.

[0057] In this embodiment 500, the first power supply voltage Vdd_diff is higher than the maximum voltage of the excitation signal, that is, higher than the maximum voltage of the excitation signal received by a pair of electrodes to which two P-type transistors are connected.

[0058] In at least one embodiment of the present disclosure, the difference between the first power supply voltage and the maximum voltage of the excitation signal can be greater than or equal to the threshold voltages of the two P-type transistors, for example. In this way, the two P-type transistors can be in the working region within the voltage range between the maximum voltage and the minimum voltage of the excitation signal, so as to minimize low-frequency noise caused by AM-PM distortion, intermodulation products, etc., and improve the sensitivity of touch detection.

[0059] In at least one embodiment of the present disclosure, the differential amplifier may include a second differential pair of transistors formed by two N-type transistors. The second differential pair of transistors is connected to a second power supply voltage. For example, the two N-type transistors may include transistor MN1 and transistor MN2. The two N-type transistors may be field effect transistors, for example, N-channel metal oxide semiconductor field effect transistors, or other types of N-type transistors, and the embodiments of the present disclosure do not limit this.

[0060] For example, the control terminals of the two N-type transistors in the second differential pair are respectively connected to two electrodes in a pair of electrodes to be detected in pairs. For example, the input voltages of the control terminals of the two N-type transistors are voltage Vin1 and voltage Vin2, respectively. The input terminals of the two N-type transistors are respectively connected to the second power supply voltage Vss_diff. According to actual requirements, the inputs of the input terminals of the two N-type transistors are current signals converted from the second power supply voltage Vss_diff via a current source. For example, the second power supply voltage Vss_diff is lower than the minimum voltage of the excitation signal, that is, lower than the minimum voltage of the excitation signal received by a pair of electrodes to which two N-type transistors are connected.

[0061] In at least one embodiment of the present disclosure, the difference between the minimum voltage of the excitation signal and the second power supply voltage can be greater than or equal to the threshold voltages of the two N-type transistors, for example. In this way, the two N-type transistors can be in the working region within the voltage range between the maximum voltage and the minimum voltage of the excitation signal, so as to minimize low-frequency noise caused by AM-PM distortion, intermodulation products, etc., and improve the sensitivity of touch detection.

[0062] Figure 6 A schematic structural diagram of a differential amplifier included in a touch controller in at least another embodiment of the present disclosure is shown.

[0063] In at least one embodiment of the present disclosure, a differential amplifier may employ a full-swing operational amplifier (also referred to as a rail-to-rail operational amplifier) such that the input-output voltage range of the device can extend from the negative supply voltage to the positive supply voltage, maximizing the output signal and increasing the dynamic range of the differential amplification circuit.

[0064] As Figure 6 shown, in an embodiment 600, the differential amplifier 611 may include two differential pairs of transistors. For example, it may include a first differential pair of transistors formed by two P-type transistors and a second differential pair of transistors formed by two N-type transistors.

[0065] For example, the first differential pair of transistors includes P-type transistors MP1 and MP2, and the second differential pair of transistors includes N-type transistors MN1 and MN2. The control terminals of the two P-type transistors of the first differential pair are respectively connected to two electrodes of a pair of electrodes to be detected in pairs. For example, the input voltages of the control terminals of the two P-type transistors are voltage Vin1 and voltage Vin2 respectively. The control terminals of the two N-type transistors of the second differential pair are respectively connected to two electrodes of a pair of electrodes to be detected in pairs. For example, the input voltages of the control terminals of the two N-type transistors are voltage Vin1 and voltage Vin2 respectively.

[0066] For example, the first differential pair of transistors is connected to a first supply voltage Vdd_diff, and the second differential pair of transistors is connected to a second supply voltage Vss_diff.

[0067] For example, the input terminals of the two P-type transistors included in the first differential pair are respectively connected to the first supply voltage Vdd_diff. According to actual requirements, the inputs of the input terminals of the two P-type transistors may be the bias currents provided by current sources inputting the first supply voltage Vdd_diff. For example, the input terminals of the two N-type transistors included in the second differential pair are respectively connected to the second supply voltage Vss_diff. According to actual requirements, the inputs of the input terminals of the two N-type transistors may be the bias currents provided by current sources inputting the second supply voltage Vss_diff.

[0068] Figure 7A shows a cross-sectional view of a full-swing operational amplifier, Figure 7B showing a cross-sectional view of a differential amplifier in at least one embodiment of the present disclosure.

[0069] For example, the power supply voltage connected to the P-type transistor in a rail-to-rail operational amplifier is usually equal to the maximum value of the voltage input at the control terminal, and the power supply voltage connected to the N-type transistor in the rail-to-rail operational amplifier is usually equal to the minimum value of the voltage input at the control terminal. Then, as the voltage input at the control terminal changes, the P-type and N-type transistors will switch between the working state and the non-working state, and the overall transconductance of the rail-to-rail operational amplifier is the sum of the transconductance of the P-type transistor and the transconductance of the N-type transistor.

[0070] For example, as Figure 7A shown, as the voltage input to the rail-to-rail operational amplifier changes from the low voltage Vss to Vdd, the curve of the transconductance gmn of the N-type transistor is curve 711, and the curve of the transconductance gmp of the P-type transistor is curve 712. The curve of the transconductance of the entire rail-to-rail operational amplifier is curve 713. According to this curve 713, it can be known that as the input voltage changes from the low voltage Vss to Vdd, the operation of the rail-to-rail operational amplifier can be divided into three operation regions, namely region 1 to region 3. In region 1 and region 3, only one pair of differential pair transistors is in the working state, and the other pair of differential pair transistors is in the off state. In region 2, both of the two differential pair transistors included in the rail-to-rail operational amplifier are in the working state, the transconductance of the rail-to-rail operational amplifier will be linearized, and correspondingly, the gain of the rail-to-rail operational amplifier will be linearized.

[0071] For example, in order to maximize the sensitivity of signal detection, a touch controller usually adjusts the voltage of the rail-to-rail operational amplifier between the power supply rails (i.e., the voltages Vss and Vdd) or in a range very close to the power supply rails. For example, this way of adjusting the voltage will inevitably cause the rail-to-rail operational amplifier to have a working state with gain non-linearity, thereby generating intermodulation products. For example, this way of adjusting the voltage will also inevitably cause the swing of the input signal of the rail-to-rail operational amplifier to fall below the threshold voltage of the transistor or above the saturation voltage, thereby causing AM-PM distortion. For example, this way of adjusting the voltage will also cause the flicker noise to be up-converted to the carrier. Therefore, this way of adjusting the voltage will cause low-frequency noise to be superimposed on the carrier, thereby contaminating the touch signal and reducing the detection sensitivity.

[0072] The touch controller provided by at least one embodiment of the present disclosure can increase the range of the voltage corresponding to operation region 2 by making the power supply voltage connected through a differential amplifier (i.e., a rail-to-rail operational amplifier) higher than the maximum voltage of the excitation signal or lower than the minimum voltage of the excitation signal, so as to reduce the low-frequency noise superimposed on the carrier to a certain extent. This is because if the first power supply voltage Vdd_diff connected to the first differential pair transistor composed of two P-type transistors is greater than the maximum voltage of the excitation signal, it will cause the voltage at the input ends of the two P-type transistors to be greater than the voltage of the sensing signal received at the two control terminals, thereby increasing the working region of the P-type transistor. For exampleFigure 7A The curve 712 in [Figure] shifts to the right. If the second power supply voltage applied to the second differential pair of transistors formed by two N-type transistors is less than the minimum voltage of the excitation signal, the voltage at the input terminals of the two N-type transistors will be less than the voltage of the sense signal applied to the two control terminals, thereby increasing the operating region of the N-type transistors. For example, Figure 7A the curve 711 in [Figure] shifts to the left.

[0073] According to at least one embodiment of the present disclosure, the difference between the first power supply voltage Vdd_diff and the maximum voltage of the excitation signal is, for example, greater than or equal to the threshold voltages of the two P-type transistors, and the difference between the minimum voltage of the excitation signal and the second power supply voltage Vss_diff is, for example, greater than or equal to the threshold voltages of the two N-type transistors. In this embodiment, as Figure 7B shown, as the voltage of the sense signal input to the rail-to-rail operational amplifier changes from the low voltage Vss to Vdd, the variation curve of the transconductance gmn of the N-type transistor is the curve 721, and the variation curve of the transconductance gmp of the P-type transistor is the curve 722. The variation curve of the transconductance of the entire rail-to-rail operational amplifier is the curve 723. It can be seen that during the process of the voltage of the sense signal changing from the low voltage Vss to the high voltage Vdd, both differential pairs of transistors included in the rail-to-rail operational amplifier are in the operating state, the rail-to-rail operational amplifier is linearized with respect to the input signal (i.e., the voltage of the sense signal provided by a pair of electrodes), the gain of the rail-to-rail operational amplifier is linearized, and AM-PM distortion and intermodulation products can be effectively reduced. In this way, no matter what the voltage of the sense signal generated based on the excitation signal is, the touch signal can be prevented from being contaminated, and the sensitivity of detecting the touch signal can be effectively guaranteed.

[0074] Figure 8 shows a comparison graph of the measurement noise of the touch controller provided by at least one embodiment of the present disclosure and the measurement noise of other touch controllers.

[0075] In at least one embodiment of the present disclosure, the excitation signal provided by the touch controller to the electrodes detected in pairs in the touch sensor can be, for example, a sine wave. Since the sine wave has a single frequency, compared with a square wave having multiple harmonic components, the intermodulation products generated by multiple signals with different frequencies entering a non-linear device (differential amplifier) can be reduced, thereby reducing the non-linear noise.

[0076] For example, in at least one embodiment of the present disclosure, the power supply voltages connected to the differential amplifier include a first power supply voltage Vdd_diff = 3.3V and a second power supply voltage Vss_diff = 0V. Square waves and sine waves of 0 - 3.3V, as well as square waves and sine waves of 1.15 - 2.15V are respectively used to excite a pair of electrodes of the touch sensor, and the touch sensor including the differential amplifier is used to detect the sensing signals provided by the pair of electrodes. During the detection process, the noise superimposed on the carrier is measured, and a measured fitting graph of the noise varying with the time length as shown in Figure 8 is obtained. The horizontal axis of this measurement graph represents the time in μs, and the vertical axis represents the quantization noise in LSB (Least Significant Bit). For example, 12bit refers to the number of bits of the device (such as the ADC mentioned below) in the touch controller, and the accuracy of the device is 1LSB.

[0077] As Figure 8 shown, compared with the scheme of using a square wave to excite a pair of electrodes of the touch sensor, the scheme of using a sine wave to excite a pair of electrodes of the touch sensor can reduce the noise superimposed on the carrier. Compared with the scheme where the high power supply voltage connected to the differential amplifier is equal to the maximum voltage of the excitation signal and the low power supply voltage connected to the differential amplifier is equal to the minimum voltage of the excitation signal, by making the high power supply voltage Vdd_diff (i.e., the first power supply voltage) connected to the differential amplifier higher than the maximum voltage of the excitation signal and the low power supply voltage Vss_diff (i.e., the second power supply voltage) connected to the differential amplifier lower than the minimum voltage of the excitation signal, the noise superimposed on the carrier can be effectively reduced.

[0078] Figure 9 shows a schematic structural diagram of the touch controller in at least one embodiment of the present disclosure.

[0079] As Figure 9 shown, in at least one embodiment of the present disclosure, each signal processing circuit of the touch controller 900 may further include an amplification circuit 921 in addition to the differential amplifier 911. The amplification circuit 921 can be used to perform secondary amplification on the amplified signal obtained by the differential amplifier 911 amplifying the differential signal to obtain an amplified differential signal.

[0080] For example, the amplification circuit 921 may include the load of the first stage of the differential operational amplifier circuit and the second stage of the differential operational amplifier circuit. After the differential amplifier amplifies the difference between the two voltage signals (i.e., the sensing signals) provided by the connected pair of electrodes and converts it into a current signal, the load of the first stage can add the current signals, and the second stage of the differential operational amplifier circuit is used to perform secondary amplification on the added signal to obtain an amplified differential signal. Through two - stage amplification, the detection sensitivity of the touch signal can be improved.

[0081] For example, in addition to the signal processing circuit, the touch controller 900 may further include a driving circuit 903. The high voltage connected to the driving circuit 903 is Vdd_High, and the low voltage connected to the driving circuit 903 is Vdd_Low. According to the specific type and structure of the driving circuit 903, the excitation signal provided by the driving circuit 903 to the electrodes in the touch sensor may be, for example, less than or equal to Vdd_High and greater than or equal to Vdd_Low.

[0082] In at least one embodiment of the present disclosure, the amplifier circuit 921 may be connected to the same power supply as the driving circuit, and need not be connected to the same power supply as the differential amplifier 911, thereby reducing the power consumption of the touch controller.

[0083] In at least one embodiment of the present disclosure, the touch controller 900 may further include, for example, an analog signal processing circuit 904. For example, the analog signal processing circuit 904 may at least include a filter and an analog-to-digital converter (ADC). The filter is used to filter the amplified differential signal to adjust the signal amplitude. The ADC is used to quantize the filtered signal, and based on the quantization result, it can be determined whether a touch signal is detected.

[0084] For example, the analog signal processing circuit 904 may also be connected to the same power supply as the driving circuit, and need not be connected to the same power supply as the differential amplifier 911, thereby reducing the power consumption of the touch controller.

[0085] Based on the touch controller for a touch sensor provided by at least one embodiment of the present disclosure, at least one embodiment of the present disclosure also provides a touch detection method for a touch sensor. The following will be combined with Figure 10 The touch detection method will be described in detail.

[0086] Figure 10 Fig. shows a schematic flowchart of the touch detection method of the touch sensor according to at least one embodiment of the present disclosure.

[0087] As Figure 10 shown, the touch detection method 1000 of this embodiment may include operations S1010 to S1020. The touch detection method may be implemented by means of the touch controller for a touch sensor provided by at least one embodiment of the present disclosure.

[0088] In operation S1010, a pair of sensing signals of a pair of connected electrodes are differentially amplified by a differential amplifier to obtain an amplified differential signal.

[0089] In operation S1020, the amplified differential signal is demodulated to obtain a touch detection result.

[0090] In at least one embodiment of the present disclosure, a first electrode included in a touch sensor may receive an excitation signal, and a pair of electrodes to be detected in pairs may be formed by two second electrodes for mutual capacitance detection. The first electrode may be one of a transverse electrode and a longitudinal electrode, and the second electrode may be the other of the transverse electrode and the longitudinal electrode.

[0091] In at least one embodiment of the present disclosure, both the first electrode and the second electrode included in the touch sensor may receive an excitation signal. A pair of electrodes to be detected in pairs may be formed by two first electrodes or two second electrodes for self-capacitance detection.

[0092] For example, a pair of electrodes to be detected in pairs is formed by two electrodes among a plurality of first electrodes or a plurality of second electrodes to which an excitation signal is applied. When an object approaches or touches a region corresponding to any one of the pair of electrodes on the display screen, the sensing signal provided by the any one electrode changes under the influence of a touch signal.

[0093] For example, the process of demodulating an amplified differential signal may include first performing a filtering process on the amplified differential signal, and then performing analog-to-digital conversion on the filtered signal to obtain a touch detection result.

[0094] In at least one embodiment of the present disclosure, when performing self-capacitance detection, a touch controller may simultaneously provide excitation signals to the first electrode and the second electrode. The touch controller may perform differential amplification processing on two sensing signals of a pair of first electrodes and perform demodulation on the obtained amplified differential signal to obtain the position of a touch point in a direction perpendicular to the first electrode. The touch controller may perform differential amplification processing on two sensing signals of a pair of second electrodes and perform demodulation on the obtained amplified differential signal to obtain the position of the touch point in a direction perpendicular to the second electrode. In this way, the position of the touch point on the two-dimensional display screen can be located, and touch detection is completed.

[0095] The touch detection method provided by at least one embodiment of the present disclosure can reduce the noise superimposed on the carrier during the detection process and improve the sensitivity of touch detection because the touch sensor provided by at least one embodiment of the present disclosure is adopted.

[0096] Based on the touch controller for a touch sensor provided by at least one embodiment of the present disclosure, at least one embodiment of the present disclosure also provides a touch control device. The following will be combined with Figure 11 This touch control device will be described in detail.

[0097] Figure 11 The block diagram of the touch control device provided by at least one embodiment of the present disclosure is shown.

[0098] As Figure 11As shown, the touch device 1100 provided in this embodiment includes a touch controller 1101 and a touch sensor 1102. The touch controller 1101 may adopt the touch controller for the touch sensor provided in at least one of the foregoing embodiments.

[0099] The touch sensor 1102 includes a plurality of first electrodes and a plurality of second electrodes arranged crosswise. For example, the touch sensor 1102 may include two electrode layers, with a plurality of first electrodes laid on one electrode layer and a plurality of second electrodes laid on the other electrode layer.

[0100] In at least one embodiment of the present disclosure, the touch controller 1101 may provide an excitation signal to the plurality of first electrodes, receive two sensing signals of a pair of electrodes among the plurality of second electrodes, and may perform differential amplification processing on the two sensing signals to determine whether there is an object approaching or touching the display screen using the principle of mutual capacitance detection. For example, the touch controller 1101 may determine whether there is an object approaching or touching the display screen based on the touch detection method provided in the present disclosure, which will not be elaborated here.

[0101] In at least one embodiment of the present disclosure, the touch controller 1101 may at least provide an excitation signal to the plurality of first electrodes, receive two sensing signals of a pair of electrodes among the plurality of first electrodes, and may perform differential amplification processing on the two sensing signals to determine whether there is an object approaching or touching the display screen using the principle of self-capacitance detection. For example, the touch controller 1101 may determine whether there is an object approaching or touching the display screen based on the touch detection method provided in the present disclosure, which will not be elaborated here. For example, the touch controller may also at least provide an excitation signal to the plurality of second electrodes, receive two sensing signals of a pair of electrodes among the plurality of second electrodes, and perform differential amplification processing on the two sensing signals. When using the principle of self-capacitance detection to determine whether there is an object approaching or touching the display screen, the touch controller 1101 may simultaneously provide excitation signals to the plurality of first electrodes and the plurality of second electrodes.

[0102] Based on the touch device provided in at least one embodiment of the present disclosure, at least one embodiment of the present disclosure also provides a display device. The following will be combined with Figure 12 to describe this display device in detail.

[0103] Figure 12 shows a structural block diagram of the display device provided in at least one embodiment of the present disclosure.

[0104] As Figure 12 shown, the display device 1200 of this embodiment includes a display screen 1201 and a touch device 1202. The touch device 1202 may adopt the touch device provided in at least one of the foregoing embodiments. For example, it may include a touch controller 1212 and a touch sensor 1222.

[0105] The touch sensor 1222 can be arranged in a stacked manner with the display screen 1201. By detecting the sensing signal provided by the touch sensor 1222 through the touch controller 1212, the position where an object approaches or touches the display screen 1201 can be detected.

[0106] For example, the material used for the front panel of the display screen 1201 can include glass, transparent conductive film, etc., and the embodiments of the present disclosure do not limit this. For example, in the embodiments of the present disclosure, the display screen can be various applicable display screens, such as a liquid crystal display screen, an organic light-emitting display screen, an electronic ink display screen, a light-emitting diode display screen, etc.

[0107] For example, the display device provided by at least one embodiment of the present disclosure can be any product or component with a display function, such as a mobile phone, a tablet computer, a television, a monitor, a notebook computer, a digital photo frame, a navigator, etc.

[0108] By setting a display device including the touch controller for the touch sensor provided by the foregoing at least one embodiment, the touch sensitivity of the display device can be improved, and the user experience can be enhanced.

[0109] In addition to the above exemplary descriptions, the following points need to be noted:

[0110] (1) The drawings of the embodiments of the present disclosure only relate to the structures involved in the embodiments of the present disclosure, and other structures can refer to the general design.

[0111] (2) Without conflict, the embodiments of the present disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.

[0112] As described above, the above are only the specific implementation manners of the present disclosure, but the protection scope of the present disclosure is not limited thereto. The protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A touch controller for a touch sensor, wherein: The touch sensor includes a plurality of first electrodes and a plurality of second electrodes arranged crosswise; The touch controller detects the plurality of first electrodes or the plurality of second electrodes in pairs; The touch controller comprises: A plurality of signal processing circuits, each of the signal processing circuits comprising: a differential amplifier connected to a pair of electrodes to be detected in pairs among the plurality of first electrodes or the plurality of second electrodes, so as to perform differential amplification processing on two sensing signals of the pair of electrodes; Wherein, the sensing signal is generated based on the excitation signal provided by the touch controller, and the power supply voltage connected to the differential amplifier includes at least one of the following: a first power supply voltage and a second power supply voltage, the first power supply voltage is higher than the maximum voltage of the excitation signal, and the second power supply voltage is lower than the minimum voltage of the excitation signal.

2. The touch controller according to claim 1, wherein: The pair of electrodes includes two electrodes to which the excitation signal is applied among the plurality of first electrodes or the plurality of second electrodes; The touch controller also includes: The first driving circuit is configured to provide the excitation signal to the pair of electrodes.

3. The touch controller according to claim 2, wherein: The first power supply voltage connected to the differential amplifier is higher than the third power supply voltage connected to the first drive circuit, and / or the second power supply voltage connected to the differential amplifier is lower than the fourth power supply voltage connected to the first drive circuit, and the third power supply voltage is higher than the fourth power supply voltage.

4. The touch controller according to claim 2 or 3, wherein: The differential amplifier includes at least one differential pair transistor. The at least one differential pair transistor comprises a first differential pair transistor composed of two P-type transistors; The first differential pair of transistors is connected to the first power supply voltage.

5. The touch controller according to claim 4, wherein: The control terminals of the two P-type transistors are respectively connected to two electrodes of the pair of electrodes; the input terminals of the two P-type transistors are connected to the first power supply voltage, A difference between the first power supply voltage and the maximum voltage of the excitation signal is greater than or equal to a threshold voltage of the two P-type transistors.

6. The touch controller according to claim 2 or 3, wherein: The differential amplifier includes at least one differential pair transistor. The at least one differential pair transistor includes a second differential pair transistor composed of two N-type transistors; The second differential pair transistors are connected to the second power supply voltage.

7. The touch controller according to claim 6, wherein: The control terminals of the two N-type transistors are respectively connected to two electrodes of the pair of electrodes; the input terminals of the two N-type transistors are connected to the second power supply voltage, Wherein, a difference between the minimum voltage of the excitation signal and the second power supply voltage is greater than or equal to the threshold voltages of the two N-type transistors.

8. The touch controller according to claim 2 or 3, wherein: The differential amplifier includes two differential pair tubes; The two differential pair transistors include a first differential pair transistor composed of two P-type transistors and a second differential pair transistor composed of two N-type transistors; The first differential pair of transistors is connected to the first power supply voltage; the second differential pair of transistors is connected to the second power supply voltage.

9. The touch controller according to claim 1 or 2, wherein: The excitation signal includes a sine wave signal.

10. The touch controller according to claim 2, wherein: The first driving circuit is configured to control the excitation signal to adjust a common mode voltage of the two sensing signals.

11. The touch controller according to claim 2, wherein: Each of the signal processing circuits further comprises: an amplifier circuit configured to perform secondary amplification on the amplified signal obtained by the differential amplifier to obtain an amplified differential signal; Wherein, the amplifier circuit and the first drive circuit are connected to the same power supply.

12. A touch device, comprising: The touch controller according to any one of claims 1 to 11; as well as The touch sensor.

13. A display device, comprising: Display screen; as well as The touch control device according to claim 12, Wherein, the touch sensor and the display screen are stacked.

14. A touch detection method for a touch sensor, wherein: The touch sensor includes a plurality of first electrodes and a plurality of second electrodes arranged crosswise; the method includes: Using a differential amplifier included in the touch controller to perform differential amplification processing on two sensing signals of a pair of electrodes connected to the differential amplifier to obtain an amplified differential signal; and Demodulating the amplified differential signal to obtain a touch detection result, Wherein, the touch controller comprises a plurality of signal processing circuits, each of the signal processing circuits comprises the differential amplifier, and the differential amplifier is connected to a pair of electrodes to be detected in pairs among the plurality of first electrodes or the plurality of second electrodes; Wherein, the sensing signal is generated based on the excitation signal provided by the touch controller; the power supply voltage connected to the differential amplifier includes at least one of the following: a first power supply voltage and a second power supply voltage, the first power supply voltage is higher than the maximum voltage of the excitation signal, and the second power supply voltage is lower than the minimum voltage of the excitation signal.

15. The method according to claim 14, wherein: The pair of electrodes includes two electrodes of the first electrode or the second electrode to which the excitation signal is applied; The differential amplifier included in the touch controller is used to perform differential amplification processing on two sensing signals of a pair of electrodes connected to the differential amplifier to obtain an amplified differential signal, including: Using a differential amplifier included in a first signal processing circuit among the plurality of signal processing circuits to perform differential amplification processing on two sensing signals of a pair of connected first electrodes to obtain an amplified differential signal corresponding to the pair of first electrodes; A differential amplifier included in a second signal processing circuit among the plurality of signal processing circuits is used to perform differential amplification processing on two sensing signals of a pair of second electrodes connected thereto, so as to obtain an amplified differential signal corresponding to the pair of second electrodes, The touch detection result is obtained by demodulating the amplified differential signal corresponding to the pair of first electrodes and the amplified differential signal corresponding to the pair of second electrodes.

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