Driving circuit, touch chip and electronic device

Abstract

Embodiments of the present application provide a driving circuit, a touch chip and an electronic device. The driving circuit is applied to a touch screen, and the touch screen comprises a driving electrode. The driving circuit comprises a first terminal, an output terminal and a plurality of first charging switches. The first terminal is configured to provide a first target voltage, and is configured to charge the driving electrode to the first target voltage. The output terminal is connected with the driving electrode. The plurality of first charging switches are connected in parallel between the first terminal and the output terminal. In the process of charging the driving electrode to the first target voltage, the number of the turned-on first charging switches gradually increases, and the driving impedance of the driving circuit gradually decreases. By adjusting the number of the turned-on first charging switches to dynamically adjust the driving impedance of the driving circuit, the voltage change rate of the driving electrode will not be too large, and the influence of the voltage of the driving electrode on the display screen is avoided.

Description

Technical Field

[0001] This invention relates to a circuit, and more particularly to a driving circuit, a touch chip, and an electronic device. Background Technology

[0002] Touchscreens and displays are widely used in electronic devices. When a conductor, such as a finger, touches or approaches the detection capacitor in the touchscreen, the capacitance changes. By detecting this change, information about the finger's proximity or contact with the touchscreen can be obtained, thus determining the user's action. However, there is coupling between the display and the touchscreen; signals from the touchscreen can introduce noise into the display's signal. Therefore, reducing this noise from the touchscreen to the display is a pressing issue. Summary of the Invention

[0003] One of the purposes of this application is to provide a driving circuit, a touch chip, and an electronic device to solve the above-mentioned problems.

[0004] According to one aspect of the present invention, a driving circuit is provided for use in a touch screen including driving electrodes. The driving circuit includes: a first terminal for providing a first target voltage; an output terminal configured to be connected to the driving electrodes; and a plurality of first charging switches connected in parallel between the first terminal and the output terminal. The first terminal is used to charge the driving electrodes to the first target voltage, and the number of activated first charging switches gradually increases during the charging process.

[0005] In one possible implementation, the first charging switch is a PMOS transistor.

[0006] In one possible implementation, the process of charging the driving electrode to the first target voltage includes a first stage and a second stage occurring sequentially, wherein the driving impedance of the driving circuit in the second stage is less than the driving impedance of the driving circuit in the first stage.

[0007] In one possible implementation, the process of charging the driving electrode to the first target voltage includes a first stage, a second stage, and a third stage occurring sequentially, wherein the driving impedance of the driving circuit in the third stage is less than the driving impedance of the driving circuit in the second stage, and the driving impedance of the driving circuit in the second stage is less than the driving impedance of the driving circuit in the first stage.

[0008] In one possible implementation, the driving circuit further includes: a second terminal for providing a second target voltage, the second target voltage being less than a first target voltage; and a plurality of first discharge switches connected in parallel between the second terminal and the output terminal. The second terminal is used to discharge the driving electrode to the second target voltage, and the number of the first discharge switches turned on gradually increases during the process of discharging the driving electrode to the second target voltage.

[0009] In one possible implementation, the second target voltage is a negative voltage.

[0010] In one possible implementation, the first discharge switch is an NMOS transistor.

[0011] In one possible implementation, the driving circuit further includes: a system ground; and a plurality of second charging switches connected in parallel between the system ground and the output terminal. The system ground is used to charge the driving electrode from the second target voltage to ground voltage. During the process of the system ground charging the driving electrode from the second target voltage to the ground voltage, the number of the second charging switches that are turned on gradually increases. Similarly, during the process of the first terminal charging the voltage of the driving electrode from the ground voltage to the first target voltage, the number of the first charging switches that are turned on gradually increases.

[0012] In one possible implementation, the driving circuit further includes: a plurality of first control switches. Each first charging switch and its corresponding first control switch are connected in series between the first terminal and the output terminal, and each second charging switch and its corresponding first control switch are connected in series between the system ground and the output terminal.

[0013] In one possible implementation, the second charging switch is an NMOS transistor, and the first control switch is a PMOS transistor.

[0014] In one possible implementation, the driving circuit further includes a plurality of second discharge switches connected in parallel between the system ground and the output terminal. The system ground is also used to discharge the driving electrode from the first target voltage to the ground voltage. During the process of discharging the driving electrode from the first target voltage to the ground voltage, the number of the second discharge switches that are turned on gradually increases. Similarly, during the process of discharging the driving electrode from the ground voltage to the second target voltage at the second terminal, the number of the first discharge switches that are turned on gradually increases.

[0015] In one possible implementation, the driving circuit further includes a plurality of second control switches. Each first discharge switch and its corresponding second control switch are connected in series between the second terminal and the output terminal, and each second discharge switch and its corresponding second control switch are connected in series between the system ground and the output terminal.

[0016] In one possible implementation, the second discharge switch is a PMOS transistor and the second control switch is an NMOS transistor.

[0017] According to another aspect of the present invention, a touch chip is provided, the touch chip including a detection circuit and the aforementioned driving circuit. When the driving circuit provides a driving signal to a driving electrode, the detection circuit is used to receive a detection signal from the detection electrode.

[0018] According to another aspect of the present invention, an electronic device is provided, the electronic device including a touch screen and the aforementioned touch chip. The touch chip is used to charge the driving electrodes in the touch screen.

[0019] The driving circuit of this application drives the driving electrode of the detection capacitor of the touch screen. In the initial stage of charging the driving electrode to the first target voltage, the driving impedance of the driving circuit is relatively large to avoid excessive voltage changes in the driving electrode. As the voltage of the driving electrode increases, the driving impedance of the driving circuit decreases, preventing the charging time from becoming excessively long. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of an electronic device according to an embodiment of this application.

[0022] Figure 2 This is a schematic diagram of a touch screen and a touch chip according to an embodiment of this application.

[0023] Figure 3 This is a schematic block diagram of a touch chip according to an embodiment of this application.

[0024] Figure 4 The equivalent circuit of a drive circuit with a fixed drive impedance is shown, and the voltage waveform of the drive electrode is shown when the drive circuit is used to drive the drive electrode.

[0025] Figure 5This is a circuit diagram of the driving circuit according to an embodiment of this application.

[0026] Figure 6 It shows in Figure 5 The voltage waveform of the driving electrode when the driving circuit drives the driving electrode.

[0027] Figures 7A-7D It shows Figure 5 The equivalent circuit of the driving circuit in the multiple stages of driving the driving electrode.

[0028] Figure 8 This is a circuit diagram of another driving circuit according to an embodiment of this application.

[0029] Figure 9 It shows in Figure 8 The voltage waveform of the driving electrode when the driving circuit drives the driving electrode. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solutions in the embodiments of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in this application should fall within the scope of protection of this application.

[0031] This application relates to an electronic device with touch and display functions. Figure 1 This is a schematic block diagram of an electronic device. (Example:) Figure 1 As shown, the electronic device includes: a touch screen 20, a display screen 30, a touch chip 10, and a display driver chip 40.

[0032] The display screen 30 includes, but is not limited to, liquid crystal displays (LCDs), organic light-emitting displays (OLEDs), plasma display panels (PDPs), micro LEDs, and mini LEDs. The touchscreen 20 is, for example, a touchscreen based on the principle of capacitance detection. The touchscreen 20 is located above the display screen 30. Users can use their fingers, styluses, or other conductors to touch the touchscreen 20 to perform corresponding touch operations. The display driver chip 40 outputs display drive signals to the display screen 30 to drive the display screen 30 to display images. The touch chip 10 outputs drive signals to the touchscreen 20 and receives detection signals from the touchscreen 20. For example, the touch chip 10 provides a drive signal to the first electrode TX of the touchscreen 20 and receives detection signals from the second electrode RX of the touchscreen 20 to determine changes in capacitance, thereby enabling user touch operations on the touchscreen 20.

[0033] In some embodiments, the touch chip 10 and the display driver chip 40 are two separate chips, each with its own independent package. In some embodiments, the touch chip 10 and the display driver chip 40 are integrated into a single chip, such as Touch and Display Driver Integration (TDDI).

[0034] As an example and not a limitation, the electronic device can be a terminal device, mobile phone, tablet, laptop, desktop computer, gaming device, in-vehicle electronic device, or wearable smart device, or other portable or mobile computing device, as well as electronic databases, automobiles, and automated teller machines (ATMs). Wearable smart devices include those that are fully functional, large in size, and capable of performing complete or partial functions without relying on a smartphone, such as smartwatches or smart glasses, as well as those that focus on a specific type of application function and require the use of other devices such as smartphones, such as various smart bracelets and smart jewelry for vital sign monitoring.

[0035] Taking display screen 30 as an example, such as Figure 1As shown, the display screen 30 includes multiple display units 31, each including a light-emitting diode (LED) D. The LED D includes a cathode, an anode, and an emissive layer. The cathode of the LED D is grounded, and the anode voltage is controlled by the display driver chip 40, causing the LED D to emit light with a target brightness. The LEDs D of the multiple display units 31 share a common cathode layer 32. The common cathode layer 32 is located on the side of the display screen 30 closest to the touchscreen 20. The first electrode TX of the touchscreen 20 and the common cathode layer 32 have a parasitic capacitance Cd2, and the second electrode RX and the common cathode layer 32 have a parasitic capacitance Cd1. Signals on the first electrode TX and the second electrode RX interfere with the common cathode layer 32 through the parasitic capacitances Cd1 and Cd2, causing the common cathode layer 32 to deviate from the target voltage (ground level). This causes the light emitted by the display units 31 to deviate from the target brightness, and the human eye may observe mixed bright and dark stripes in the current display screen, i.e., a water ripple problem.

[0036] Figure 2 This is a schematic diagram of a touch screen according to an embodiment of this application. Figure 2 As shown, the touch screen 20 includes a plurality of first electrodes TX1-TX extending along a first direction. m and multiple second electrodes RX1-RX extending along the second direction n The first direction and the second direction are two different directions that are perpendicular to each other. The touch screen 20 can use two capacitance detection methods: self-capacitance and mutual capacitance.

[0037] During self-capacitance detection, the touch chip 10 directs the signal to the first electrode TX. i (1≤i≤m) provides the drive signal and detects the first electrode TX. i The change in the self-capacitance Cs (i.e., the detection capacitance) to ground, and the first electrode TX i It serves as both a driving electrode and a detection electrode. Furthermore, the touch chip 10 directs the signal to the second electrode RX. j (1≤j≤n) provides the drive signal to detect the second electrode RX. j The change in the self-capacitance Cs to ground (i.e., the detection capacitance), and the second electrode RX. j It serves as both a driving electrode and a detection electrode. Based on the first electrode TX... i Second electrode RX j The change in the self-capacitance Cs to ground is used to identify the user's touch operation.

[0038] During mutual capacitance detection, the first electrode TX i Second electrode RX j The first electrode TX serves as both the driving electrode and the detection electrode. i Second electrode RX j Mutual capacitance C1 is formed. Figure 2Only the first electrode TX is shown. m-1 The mutual capacitance C1 between the first electrode TX1 and the second electrode RX2. The touch chip 10 directs the signal to the first electrode TX1-TX2. m Drive signals are provided sequentially from the second electrode RX1-RX n The system receives a detection signal to detect changes in the mutual capacitance C1 (i.e., the detection capacitance). The user's touch operation is identified based on the changes in the mutual capacitance C1. For example, the touch chip 10 sends a drive signal to the first electrode TX1, from the second electrode RX1-RX... n Receive detection signals, based on the first electrode TX1 and the second electrode RX1-RX n The mutual capacitance C1 between the electrodes determines whether the touch position corresponds to the position of the first electrode TX1. The mutual capacitance C1 is the detection capacitance.

[0039] During self-capacitance detection, the first electrode TX i Second electrode RX j Both are driving electrodes and detection electrodes. During mutual capacitance detection, the first electrode TX... i As the driving electrode, the second electrode RX j This is the detection electrode.

[0040] Figure 3 This is a schematic block diagram of a touch chip according to an embodiment of this application. The touch chip 10 includes a driving circuit 100 and a detection circuit 200. The driving circuit 100 provides a driving signal to the driving electrode through its output terminal OUT. The detection circuit 200 receives a detection signal from the detection electrode, amplifies the detection signal, and converts the amplified signal into a digital signal. The following description uses mutual capacitance detection as an example. The implementation of self-capacitance detection is similar and will not be repeated.

[0041] The driving electrode has a capacitance Cs to ground, which can be referred to as the load capacitance of the driving electrode. The driving circuit 100 inputs a driving signal to the driving electrode TX, that is, the driving circuit 100 charges the load capacitance of the driving electrode TX. The driving signal needs to make the driving electrode RX reach the target voltage AVDD.

[0042] Figure 4 The equivalent circuit of a drive circuit with a fixed drive impedance and the voltage waveform of the drive electrodes when the drive circuit is used to drive the drive electrodes are shown. Figure 4 As shown, the drive circuit includes a switch K. One end of switch K is connected to terminal N, which provides the target voltage AVDD, and the other end of switch K is connected to the drive electrode TX. Switch K has an on-resistance R. k .because Figure 4 The drive circuit includes one switch K, therefore the drive circuit has a fixed drive impedance (equal to R). kWhen switch K is turned on, terminal N charges the drive electrode TX through switch K. Charging the drive electrode TX is equivalent to charging the load capacitor CL. Figure 4 The voltage change of the driving electrode TX during charging is also shown. The initial voltage of the driving electrode TX is, for example, 0V. After charging time T, the voltage of the driving electrode TX increases from 0V to the target voltage AVDD. In the initial stage of charging time T, the voltage of the driving electrode TX is relatively low, the voltage difference across switch K is large, the charging current is large, and the charging speed of the driving electrode TX is fast. As the voltage of the driving electrode TX gradually increases, the voltage difference across switch K gradually decreases, the charging current gradually decreases, and the charging speed of the driving electrode TX gradually decreases. In the initial stage of charging time T, the rapid increase of the driving electrode TX couples to the common cathode 32 of the display screen 30 through the parasitic capacitance Cd2, interfering with the signal of the common cathode 32, and thus interfering with the display of the display screen 30, causing the water ripple problem. Similarly, in the initial stage of the process of discharging the driving electrode TX from the target voltage AVDD to 0V, the discharge current is large, and the rapid decrease of the driving electrode TX also interferes with the display of the display screen 30.

[0043] In view of this, this application provides a driving circuit for use in a touch screen, which has a dynamically adjustable driving impedance. When the voltage of the driving electrode differs significantly from the target voltage, the driving impedance of the driving circuit is larger, preventing the voltage change rate of the driving electrode TX from being too rapid. This reduces the interference of the driving electrode TX voltage on the display screen, improving or even eliminating display abnormalities perceptible to the human eye. Subsequently, by reducing the driving impedance, the charging / discharging time is prevented from becoming excessively long.

[0044] Figure 5 This is a circuit diagram of a driving circuit provided in an embodiment of this application. Figure 5 As shown, the driving circuit 100 includes: a first terminal N1, a second terminal N2, an output terminal OUT, a first charging switch P1, a first charging switch P2, a first charging switch P3, a first discharging switch N1, a first discharging switch N2, and a first discharging switch N3. The output terminal OUT of the driving circuit 100 is used to output a driving signal. Figure 5 As shown, the output terminal OUT is connected to the drive electrode TX and is used to charge the load capacitor.

[0045] Terminal N1 provides a first target voltage PV, and terminal N2 provides a second target voltage NV. Terminal N1 is connected, for example, to a first voltage generating circuit, which generates the first target voltage PV. Terminal N2 is connected, for example, to a second voltage generating circuit, which generates the second target voltage NV. The first target voltage PV is greater than the second target voltage NV. The first target voltage PV is a positive voltage, and the second target voltage NV can be 0V (ground voltage) or a negative voltage. Terminal N1 provides positive charge to the driving electrode TX, charging the driving electrode TX to the first target voltage PV. The first target voltage PV is, for example, the power supply voltage. When the second target voltage NV is negative, the second voltage generating circuit is, for example, a charge pump. Terminal N2 provides negative charge to the driving electrode TX, discharging the driving electrode TX to the second target voltage NV. When the second target voltage NV is 0V, the second voltage generating circuit is, for example, system ground.

[0046] First charging switches P1, P2, and P3 are connected in parallel between the first terminal N1 and the output terminal OUT. Each of the first charging switches P1-P3 includes one or more transistors. The first charging switches P1-P3 are, for example, PMOS transistors. The on / off state of first charging switch P1 is controlled by control signal H1; the on / off state of first charging switch P2 is controlled by control signal H2; and the on / off state of first charging switch P3 is controlled by control signal H3. For example, in response to a first level (e.g., low level) of control signal H1, first charging switch P1 is turned on; in response to a second level (e.g., high level) of control signal H1, first charging switch P1 is turned off; in response to a first level (e.g., low level) of control signal H2, first charging switch P2 is turned on; in response to a second level (e.g., high level) of control signal H2, first charging switch P2 is turned off; in response to a first level (e.g., low level) of control signal H3, first charging switch P3 is turned on; and in response to a second level (e.g., high level) of control signal H3, first charging switch P3 is turned off. The on-resistances of the first charging switches P1-P3 can be the same or different. For example, the on-resistances of the first charging switches P1-P3 can be made different by making the aspect ratios of the PMOS transistors different.

[0047] First discharge switches N1, N2, and N3 are connected in parallel between the output terminal OUT and the second terminal N2. Each of the first discharge switches N1-N3 includes one or more transistors. The first discharge switches N1-N3 are, for example, NMOS transistors. The on / off state of the first discharge switch N1 is controlled by control signal L1; the on / off state of the first discharge switch N2 is controlled by control signal L2; and the on / off state of the first discharge switch N3 is controlled by control signal L3. For example, in response to a first level (e.g., high level) of control signal L1, the first discharge switch N1 is turned on; in response to a second level (e.g., low level) of control signal L1, the first discharge switch N1 is turned off; in response to a first level (e.g., high level) of control signal L2, the first discharge switch N2 is turned on; in response to a second level (e.g., low level) of control signal L2, the first discharge switch N2 is turned off; in response to a first level (e.g., high level) of control signal L3, the first discharge switch N3 is turned on; and in response to a second level (e.g., low level) of control signal L3, the first discharge switch N3 is turned off. The on-resistances of the first discharge switches N1-N3 can be the same or different. For example, the on-resistances of the first discharge switches N1-N3 can be different by making the aspect ratios of the NMOS transistors different.

[0048] In some embodiments, the first charging switch P1 and the first discharging switch N1 can form a driving branch 111, the first charging switch P2 and the first discharging switch N2 can form a driving branch 112, and the first charging switch P3 and the first discharging switch N3 can form a driving branch 113.

[0049] like Figure 5 As shown, the drive circuit 100 also includes a control circuit 120, which provides control signals H1-H3 and control signals L1-L3.

[0050] The driving circuit 100 of the touch chip 10 drives the driving electrode TX of the touch screen 20, also known as coding. The driving process of the driving circuit 100 on the driving electrode TX includes, for example, charging the driving electrode TX to a first target voltage PV and discharging the driving electrode TX to a second target voltage NV. During the process of charging the voltage of the driving electrode TX to the first target voltage PV, the driving impedance of the driving circuit 100 gradually decreases. This gradual decrease in driving impedance can be achieved by gradually increasing the number of first charging switches that are turned on. For example, the process of the driving circuit charging the driving electrode to the first target voltage PV includes three stages: a first stage, a second stage, and a third stage, occurring sequentially. In the third stage, the driving impedance of the driving circuit is less than that in the second stage, and in the second stage, the driving impedance of the driving circuit is less than that in the first stage. The number of first charging switches turned on are 1, 2, and 3, respectively.

[0051] In one embodiment, in the first stage, the control circuit 120 turns on the first charging switch P1 via control signal H1; in the second stage, the control circuit 120 further turns on the first charging switch P2 via control signal H2; and in the third stage, the control circuit 120 further turns on the first charging switch P3 via control signal H3. From the first stage to the third stage, the number of first charging switches connected in parallel gradually increases, and the driving impedance of the drive circuit 100 gradually decreases.

[0052] In another embodiment, in the first stage, the control circuit 120 turns on the first charging switch P1 via control signal H1; in the second stage, the control circuit 120 turns on the first charging switches P2 and P3 via control signals H2 and H3; and in the third stage, the control circuit 120 turns on the first charging switches P1-P3 via control signals H1-H3. In this embodiment, the on-resistance of the first charging switch P1 is greater than the on-resistance of the first charging switches P2 and P3 connected in parallel. From the first stage to the third stage, the driving impedance of the drive circuit 100 gradually decreases.

[0053] In another embodiment, the on-resistance of the first charging switch P1 is R. k1 The on-resistance of the second charging switch P2 is R. k2 The on-resistance of the first charging switch P3 is R. k3 R k1 >R k2 >R k3 For example, the aspect ratio of the first charging switch P1 is smaller than that of the first charging switch P2, and the aspect ratio of the first charging switch P2 is smaller than that of the first charging switch P3. The charging process includes five sequential stages. In the first stage, the control circuit 120 turns on the first charging switch P1 through the control signal H1, and the driving impedance of the drive circuit 100 is R. k1 In the second stage, the control circuit 120 turns on the first charging switch P2 through the control signal H2, and the driving impedance of the drive circuit 100 is R. k2 In the third stage, the control circuit 120 turns on the first charging switch P3 through the control signal H3, and the driving impedance of the drive circuit 100 is R. k3 In the fourth stage, the control circuit 120 turns on the first charging switches P2 and P3 through control signals H2 and H3, and the driving impedance of the drive circuit 100 is 1 / (1 / R). k3 +1 / R k2 Alternatively, control circuit 120 can activate first charging switches P1 and P3 via control signals H1 and H3, and the driving impedance of drive circuit 100 is 1 / (1 / R). k3 +1 / R k1In the fifth stage, the control circuit 120 turns on the first charging switches P1-P3 through control signals H1-H3, and the driving impedance of the drive circuit 100 is 1 / (1 / R). k3 +1 / R k1 +1 / R k2 From the first stage to the fifth stage, the driving impedance of the driving circuit 100 gradually decreases.

[0054] In this embodiment, the number of first charging switches and the number of first discharging switches are merely examples. The number of first charging switches in the driving circuit 10 can also be two or more than three, and the number of first discharging switches can also be two or more than three. That is, the process of the driving circuit charging the driving electrode to the first target voltage PV includes at least two stages, which are a first stage and a second stage that occur sequentially. In the second stage, the driving impedance of the driving circuit is less than the driving impedance of the driving circuit in the first stage.

[0055] By dynamically adjusting the number of the first charging switches that are turned on, the driving impedance of the driving circuit is adjusted to avoid excessive voltage change rate of the driving electrode TX, thereby reducing the interference of the driving electrode TX voltage on the display screen 30. In addition, as the driving electrode TX voltage increases, the voltage difference across the first charging switch decreases, the driving impedance of the driving circuit 100 decreases, and the charging current at each stage of the charging process can be basically consistent, so that the voltage change rate of the driving electrode TX is basically consistent.

[0056] Similarly, during the discharge of the driving electrode TX to the second target voltage NV, the driving impedance of the driving circuit 100 gradually decreases. This gradual decrease in driving impedance can be achieved by gradually increasing the number of first discharge switches that are turned on. For example, the discharge process includes three sequential stages. In the first stage, the control circuit 120 turns on the first discharge switch N1 via control signal L1; in the second stage, the control circuit 120 further turns on the first discharge switch N2 via control signal L2; and in the third stage, the control circuit 120 further turns on the first discharge switch N3 via control signal L3. From the first stage to the third stage, the number of first discharge switches turned on is 1, 2, and 3 respectively, and the driving impedance of the driving circuit 100 gradually decreases. By dynamically adjusting the number of first discharge switches turned on, the driving impedance of the driving circuit is adjusted to avoid excessive voltage change rate of the driving electrode TX, thereby reducing the interference of the driving electrode TX voltage on the display screen 30. Furthermore, as the voltage of the driving electrode TX decreases, the voltage difference across the first discharge switch decreases, the driving impedance of the driving circuit 100 decreases, and the discharge current at each stage of the discharge process can be basically consistent, so that the voltage change rate of the driving electrode TX is basically consistent.

[0057] Figure 6 It shows in Figure 5The waveform of the voltage of the driving electrode TX during the charging process of the driving circuit. Figures 7A-7D It shows Figure 5 The equivalent circuit of the driving circuit 100 in the multiple stages of driving the driving electrode TX. Figures 7A-7D In the illustrated embodiment, the first charging switch P1, the first charging switch P2, and the first charging switch P3 sequentially enter the conducting state. The following is in conjunction with... Figure 6 and Figures 7A-7D Describe the operation of the drive circuit 100. Take the second target voltage NV as an example when it is 0V.

[0058] During the charging process of the driving electrode TX, the voltage of the driving electrode TX increases from the second target voltage NV to the first target voltage PV. For example... Figure 6 As shown, the charging process extends from time t0 to time t3. The charging process comprises three stages: the first stage from time t0 to time t1, the second stage from time t1 to time t2, and the third stage from time t2 to time t3. During the charging process, the first discharge switches N1-N3 remain open.

[0059] Before charging begins, the first charging switches P1-P3 are all in the open state, and the voltage of the driving electrode TX is the second target voltage NV. The equivalent circuit of the driving circuit 100 is as follows: Figure 7A As shown.

[0060] In the first stage, such as Figure 7B As shown, the first charging switch P1 is turned on, and the first charging switches P2 and P3 are turned off. The driving impedance of the driving circuit 100 is equal to the on impedance R of the first charging switch P1. k1 The voltage at the drive electrode TX rises to the first intermediate voltage.

[0061] In the second stage, such as Figure 7C As shown, the first charging switches P1 and P2 are on, and the first charging switch P3 is off. The charging path of the driving electrode TX includes the first charging switches P1 and P2 connected in parallel. The driving impedance of the driving circuit 100 is equal to the on-resistance R of the first charging switch P1. k1 and the on-resistance R of the first charging switch P2 k2 The parallel connection. The driving impedance of the driving circuit 100 in the second stage is less than its driving impedance in the first stage. The voltage of the driving electrode TX rises to the second intermediate voltage.

[0062] In the third stage, such as Figure 7D As shown, all first charging switches P1-P3 are turned on, and the charging path of the driving electrode TX includes the first charging switches P1-P3 connected in parallel. The driving impedance of the driving circuit 100 is equal to the on-resistance R of the first charging switch P1. k1The on-resistance R of the first charging switch P2 k2 The on-resistance R of the first charging switch P3 k3 The parallel connection. The driving impedance of the driving circuit 100 in the third stage is less than its driving impedance in the second stage. The voltage of the driving electrode TX rises to the first target voltage PV.

[0063] like Figure 6 and Figures 7A-7D As shown, during the charging process of the driving electrode TX by the driving circuit 10, the voltage of the driving electrode TX gradually increases, while the voltage difference across the first charging switch gradually decreases. In the initial stage of the charging process, the driving circuit 100 has a large driving impedance, resulting in a smaller charging current and a smaller rate of voltage change of the driving electrode TX, thus reducing the interference of the driving electrode TX voltage on the display screen 30. Furthermore, by adjusting the number of the first charging switches that are turned on, the driving impedance of the driving circuit 100 decreases sequentially in the three stages. Therefore, the driving circuit 10 provides a relatively consistent driving current to the driving electrode TX in the three stages of the charging process. Consequently, the voltage of the driving electrode TX has a relatively consistent rate of change throughout the entire charging process.

[0064] During the discharge process of the driving electrode TX, the voltage of the driving electrode TX decreases from the first target voltage PV to the second target voltage NV. Similar to the charging process, the first charging switches P1-P3 remain open, and the number of the first discharging switches N1-N3 that are turned on gradually increases, causing the driving impedance of the driving circuit 100 to gradually decrease.

[0065] The driving circuit 100 of this application has a dynamically adjustable driving impedance. Compared with a driving circuit with a fixed driving impedance, the driving circuit of this application has the following effects. If the driving circuit has a fixed driving impedance 1 / (1 / R) k1 +1 / R k2 +1 / R k3 During the initial stage of the charging (discharging) process, the voltage of the driving electrode TX exhibits a large rate of change, causing a ripple effect on the display screen 30. If the driving circuit has a fixed driving impedance R... k1 If the charging (discharging) process takes too long, the driving frequency (coding frequency) will decrease. By dynamically adjusting the driving impedance of the driving circuit, the driving impedance of the driving circuit 100 is relatively large in the early stage of the charging (discharging) process and relatively small in the later stage, so as to avoid excessive voltage change rate of the driving electrode TX and avoid water ripple problem on the display screen; as the voltage of the driving electrode TX increases, the driving impedance of the driving circuit 100 decreases, so as to avoid the charging (discharging) process taking too long.

[0066] Figure 8This is a circuit diagram of another driving circuit provided in an embodiment of this application. For example... Figure 8 As shown, the driving circuit 100 includes: a first terminal N1, a second terminal N2, an output terminal OUT, first charging switches P11-P15, first discharging switches N11-N15, second charging switches N21-N25, second discharging switches P21-P25, first control switches P31-P35, and second control switches N31-N35. The output terminal OUT of the driving circuit 100 is connected to the driving electrode TX. The output terminal OUT of the driving circuit 100 provides a driving signal. In this embodiment, the number of the first charging switch, second charging switch, first discharging switch, second discharging switch, first control switch, and second control switch is only an example and is not limited to 5.

[0067] The first terminal N1 is used to provide a first target voltage PV, which is a positive voltage. The second terminal N2 is used to provide a second target voltage NV, which is a negative voltage. For example, the first terminal N1 is connected to a first voltage generating circuit that provides the first target voltage PV, and the second terminal N2 is connected to a second voltage generating circuit that provides the second target voltage PV.

[0068] The first charging switches P11-P15 are connected in parallel between the first terminal N1 and the output terminal OUT. The first terminal N1 charges the driving electrode TX to the first target voltage PV. Specifically, the first terminal N1 provides positive charge to the driving electrode TX through the first charging switches P11-P15, raising the voltage of the driving electrode TX to the first target voltage PV. Each of the first charging switches P11-P15 and its corresponding first control switch are connected in series between the first terminal N1 and the output terminal OUT. Specifically, the first charging switch P11 and the first control switch P31 are connected in series between the first terminal N1 and the output terminal OUT, the first charging switch P12 and the first control switch P32 are connected in series between the first terminal N1 and the output terminal OUT, the first charging switch P13 and the first control switch P33 are connected in series between the first terminal N1 and the output terminal OUT, the first charging switch P14 and the first control switch P34 are connected in series between the first terminal N1 and the output terminal OUT, and the first charging switch P15 and the first control switch P35 are connected in series between the first terminal N1 and the output terminal OUT. The first charging switches P11-P15 are, for example, PMOS transistors. The on / off state of the first charging switch P11 is controlled by control signal H1, the on / off state of the first charging switch P12 is controlled by control signal H2, the on / off state of the first charging switch P13 is controlled by control signal H3, the on / off state of the first charging switch P14 is controlled by control signal H4, and the on / off state of the first charging switch P15 is controlled by control signal H5. For example, in response to a first level (e.g., low level) of control signals H1-H5, the first charging switches P11-P15 are turned on; in response to a second level (e.g., high level) of control signals H1-H5, the first charging switches P11-P15 are turned off. The high level of control signals H1-H5 is, for example, a first target voltage PV, and the low level is, for example, 0V. The on-resistance of the first charging switches P11-P15 can be the same or different.

[0069] The second charging switches N21-N25 are connected in parallel between the system ground GND and the output terminal OUT. The system ground GND charges the driving electrode TX from the second target voltage NV to ground voltage. Specifically, the negative charge on the driving electrode TX is released to the system ground GND through the second charging switches, causing the voltage of the driving electrode TX to rise from the second target voltage NV to ground voltage. Each of the second charging switches N21-N25 and its corresponding first control switch are connected in series between the system ground GND and the output terminal OUT. Specifically, the second charging switch N21 and the first control switch P31 are connected in series between the system ground GND and the output terminal OUT; the second charging switch N22 and the first control switch P32 are connected in series between the system ground GND and the output terminal OUT; the second charging switch N23 and the first control switch P33 are connected in series between the system ground GND and the output terminal OUT; the second charging switch N24 and the first control switch P34 are connected in series between the system ground GND and the output terminal OUT; and the second charging switch N25 and the first control switch P35 are connected in series between the system ground GND and the output terminal OUT. The second charging switches N21-N25, for example, implement NMOS transistors. The turning on and off of the second charging switches N21-N25 is controlled by a control signal HN. For example, in response to a first level (e.g., a high level) of the control signal HN, the second charging switches N21-N25 turn on; in response to a second level (e.g., a low level) of the control signal HN, the second charging switches N21-N25 turn off. A high level of the control signal HN is, for example, a first target voltage PV, and a low level is, for example, 0V. The on-resistances of the second charging switches N21-N25 can be the same or different.

[0070] First discharge switches N11-N15 are connected in parallel between the second terminal N2 and the output terminal OUT. The second terminal N2 discharges the driving electrode TX to the second target voltage NV. Specifically, the second terminal N2 provides negative charge to the driving electrode TX through the first discharge switches N11-N15, thereby reducing the voltage of the driving electrode TX to the second target voltage NV. Each of the first discharge switches N11-N15 and its corresponding second control switch are connected in series between the second terminal N2 and the output terminal OUT. Specifically, the first discharge switch N11 and the second control switch N31 are connected in series between the second terminal N2 and the output terminal OUT; the first discharge switch N12 and the second control switch N32 are connected in series between the second terminal N2 and the output terminal OUT; the first discharge switch N13 and the second control switch N33 are connected in series between the second terminal N2 and the output terminal OUT; the first discharge switch N14 and the second control switch N34 are connected in series between the second terminal N2 and the output terminal OUT; and the first discharge switch N15 and the second control switch N35 are connected in series between the second terminal N2 and the output terminal OUT. The first discharge switches N11-N15 are, for example, NMOS transistors. The switching on and off of the first discharge switch N11 is controlled by control signal L1, the switching on and off of the first discharge switch N12 is controlled by control signal L2, the switching on and off of the first discharge switch N13 is controlled by control signal L3, the switching on and off of the first discharge switch N14 is controlled by control signal L4, and the switching on and off of the first discharge switch N15 is controlled by control signal L5. For example, in response to a first level (e.g., a high level) of control signals L1-L5, the first discharge switches N11-N15 are turned on; in response to a second level (e.g., a low level) of control signals L1-L5, the first discharge switches N11-N15 are turned off. The high level of control signals L1-L5 is, for example, 0V, and the low level is, for example, a second target voltage NV. The on-resistance of the first discharge switches N11-N15 can be the same or different.

[0071] The second discharge switches P21-P25 are connected in parallel between system ground GND and the output terminal OUT. System ground GND discharges the drive electrode TX from the first target voltage PV to 0V. Specifically, the positive charge on the drive electrode TX is released to system ground GND through the second discharge switches P21-P25. Each of the second discharge switches P21-P25 and its corresponding second control switch are connected in series between system ground and the output terminal OUT. Specifically, second discharge switch P21 and second control switch N31 are connected in series between system ground and the output terminal OUT, second discharge switch P22 and second control switch N32 are connected in series between system ground and the output terminal OUT, second discharge switch P23 and second control switch N33 are connected in series between system ground and the output terminal OUT, second discharge switch P24 and second control switch N34 are connected in series between system ground and the output terminal OUT, and second discharge switch P25 and second control switch N35 are connected in series between system ground and the output terminal OUT. The second discharge switches P21-P25 are, for example, PMOS transistors. The switching on and off of the second charging switches P21-P25 is controlled by the control signal LN. For example, in response to a first level (low level) of the control signal LN, the second discharging switches P21-P25 are turned on; in response to a second level (high level) of the control signal LN, the second discharging switches P21-P25 are turned off. The high level of the control signal LN is, for example, 0V, and the low level is, for example, the second target voltage NV. The on-resistance of the second discharging switches P21-P25 can be the same or different.

[0072] The first control switches P31-P35 are, for example, PMOS transistors. The on / off state of the first control switch P31 is controlled by control signal ZP1, the on / off state of the first control switch P32 is controlled by control signal ZP2, the on / off state of the first control switch P33 is controlled by control signal ZP3, the on / off state of the first control switch P34 is controlled by control signal ZP4, and the on / off state of the first control switch P35 is controlled by control signal ZP5. For example, in response to a first level (e.g., low level) of control signals ZP1-ZP5, the first control switches P31-P35 are turned on; in response to a second level (e.g., high level) of control signals ZP1-ZP5, the first control switches P31-P35 are turned off. The high level of control signals ZP1-ZP5 is, for example, 0V, and the low level is, for example, a second target voltage NV. The first control switches P31-P35 also prevent excessive source-drain voltage difference between the corresponding first charging switches P11-P15. Taking the first control switch P31 and the first charging switch P11 as an example, when the voltage of the driving electrode TX is the second target voltage NV, if there is no first control switch P31, the source-drain voltage difference of the first charging switch P11 is the first target voltage PV - the second target voltage NV.

[0073] The second control switches N31-N35 are, for example, NMOS transistors. The switching on and off of the second control switch N31 is controlled by control signal ZN1, the switching on and off of the second control switch N32 is controlled by control signal ZN2, the switching on and off of the second control switch N33 is controlled by control signal ZN3, the switching on and off of the second control switch N34 is controlled by control signal ZN4, and the switching on and off of the second control switch N35 is controlled by control signal ZN5. For example, in response to a first level (e.g., a high level) of control signals ZN1-ZN5, the second control switches N31-N35 are turned on; in response to a second level (e.g., a low level) of control signals ZN1-ZN5, the second control switches N31-N35 are turned off. The high level of control signals ZN1-ZN5 is, for example, a first target voltage PV, and the low level is, for example, 0V. The second control switches N31-N35 are also used to prevent the source-drain voltage difference of the corresponding first discharge switches N11-N15 from becoming too large. Taking the second control switch N31 and the first discharge switch N11 as an example, when the voltage of the driving electrode TX is the first target voltage PV, if there is no second control switch N31, the source-drain voltage difference of the first discharge switch N11 is the first target voltage PV minus the second target voltage NV. Figure 8 As shown, the second discharge switches P21-P25 all receive the control signal LN. Whether the second discharge switches P21-P25 are connected to the output terminal OUT is controlled by their corresponding second control switches N31-N35. The second discharge switches P21-P25 can also be controlled to be turned on and off by five control signals respectively, but this would increase the complexity of the control circuit.

[0074] The drive circuit 100 also includes a control circuit. Figure 8 (Not shown), the control circuit is used to provide control signals H1-H5, control signals L1-L5, control signals HN and LN, control signals ZP1-ZP5, and control signals ZN1-ZN5. For example... Figure 8 As shown, the second charging switches N21-N25 all receive the control signal HN. Whether the second charging switches N21-N25 are connected to the output terminal OUT is controlled by their corresponding first control switches P31-P35. The second charging switches N21-N25 could also be controlled to turn on and off by five separate control signals, but this would increase the complexity of the control circuit. Similarly, the second discharging switches P21-P25 all receive the control signal LN. Whether the second discharging switches P21-P25 are connected to the output terminal OUT is controlled by their corresponding second control switches N31-N35. The second discharging switches P21-P25 could also be controlled to turn on and off by five separate control signals, but this would also increase the complexity of the control circuit.

[0075] Figure 8The driving circuit 100 shown illustrates a process in which the voltage of the driving electrode TX is charged from a second target voltage NV to a first target voltage PV. This process includes: a process 1 of charging the voltage of the driving electrode TX from the second target voltage NV to 0, and a process 2 of charging the voltage of the driving electrode TX from 0 to the first target voltage PV. In process 1, the negative charge on the driving electrode TX is released to system ground. In process 2, the positive charge at the first terminal N1 is transferred to the driving electrode TX. Figure 8 The driving circuit 100 shown discharges the voltage of the driving electrode TX from a first target voltage PV to a second target voltage NV, including: process 3 of discharging the voltage of the driving electrode TX from the first target voltage PV to 0, and process 4 of discharging the voltage of the driving electrode TX from 0 to the second target voltage NV. In process 3, the positive charge on the driving electrode TX is released to system ground. In process 4, the negative charge at the second terminal N2 is transferred to the driving electrode TX.

[0076] Figure 9 It shows in Figure 8 The waveform of the voltage of the driving electrode TX during the driving process of the driving circuit 100 to the driving electrode TX. Figure 9 The solid line in the middle represents Figure 8 The driving circuit 100 shown uses a dynamically adjusted driving impedance to control the voltage at the driving electrode TX. For example... Figure 9 As shown, the charging process occurs from time t0 to time t11. From time t0 to time t5, the drive circuit 100 charges the drive electrode TX from the second target voltage NV to 0V. From time t6 to time t11, the drive circuit 100 charges the drive electrode TX from 0V to the first target voltage PV. The charging process can be divided into 11 stages. During the charging process, the first discharge switches N11-N15 are all in the open state.

[0077] In the exemplary description below, the first charging switches P11-P15 are PMOS, the first discharging switches N11-N15 are NMOS, the second charging switches N21-N25 are NMOS, the second discharging switches P21-P25 are PMOS, the first control switches P31-P35 are PMOS, and the second control switches N31-N35 are NMOS. The high level of control signals L1-L5, LN, and ZP1-ZP5 is 0V, and the low level is NV. The high level of control signals H1-H5, HN, and ZN1-ZN5 is PV, and the low level is 0V.

[0078] In the first stage (from time t0 to time t1), control signals L1-L5 are low, control signals ZN1-ZN5 are low, control signal LN is high, control signals H1-H5 are high, control signal HN is high, control signal ZP1 is low, and control signals ZP2-ZP5 are high. The first control switch P31 is turned on, the first control switches P32-P35 are turned off, and the second charging switch N21 is turned on. The driving electrode TX releases negative charge through the second charging switch N21, systematically charging the driving electrode TX from the second target voltage NV to the first intermediate voltage.

[0079] In the second stage (from time t1 to time t2), control signals L1-L5 are low, control signals ZN1-ZN5 are low, control signal LN is high, control signals H1-H5 are high, control signal HN is high, control signals ZP1 and ZP2 are low, and control signals ZP3-ZP5 are high. First control switches P31 and P32 are turned on, first control switches P33-P35 are turned off, and second charging switches N21 and N22 are turned on. The driving electrode TX releases negative charge through the second charging switches N21 and N22, systematically charging the driving electrode TX from the first intermediate voltage to the second intermediate voltage.

[0080] In the third stage (from time t2 to time t3), control signals L1-L5 are low, control signals ZN1-ZN5 are low, control signal LN is high, control signals H1-H5 are high, control signal HN is high, control signals ZP1-ZP3 are low, and control signals ZP4-ZP5 are high. The first control switches P31-P33 are turned on, the first control switches P34-P35 are turned off, and the second charging switches N21-N23 are turned on. The driving electrode TX releases negative charge through the second charging switches N21-N23, systematically charging the driving electrode TX from the second intermediate voltage to the third intermediate voltage.

[0081] In the fourth stage (from time t3 to time t4), control signals L1-L5 are low, control signals ZN1-ZN5 are low, control signal LN is high, control signals H1-H5 are high, control signal HN is high, control signals ZP1-ZP4 are low, and control signal ZP5 is high. The first control switches P31-P34 are on, the first control switch P35 is off, and the second charging switches N21-N24 are on. The driving electrode TX releases negative charge through the second charging switches N21-N24, systematically charging the driving electrode TX from the third intermediate voltage to the fourth intermediate voltage.

[0082] In the fifth stage (from time t4 to time t5), control signals L1-L5 are low, control signals ZN1-ZN5 are low, control signal LN is high, control signals H1-H5 are high, control signal HN is high, and control signals ZP1-ZP5 are low. The first control switches P31-P35 are turned on, and the second charging switches N21-N25 are turned on. The driving electrode TX releases negative charge through the second charging switches N21-N25, systematically charging the driving electrode TX from the fourth intermediate voltage to 0.

[0083] In the first to fifth stages, the control signal LN disconnects the second discharge switches P21-P25 to prevent the output terminal OUT from being connected to ground through the second control switch and the second discharge switch.

[0084] During the process of charging the voltage of the driving electrode TX from the second target voltage NV to 0V, the number of the second charging switches N21-N25 that are turned on are 1, 2, 3, 4, and 5 respectively, and the driving impedance of the driving circuit 100 gradually decreases. In contrast, Figure 9 The dashed line in the diagram represents the voltage of the drive electrode TX when the drive circuit 100 uses a fixed drive impedance. The second charging switches N21-N25 of the drive circuit 100 are in the ON state from the first stage to the fifth stage, and the drive circuit 100 has a fixed drive impedance. The drive electrode TX is systematically charged through the second charging switches N21-N25, and the drive electrode TX is charged to 0V at time t41. Figure 9 As shown, if a small fixed driving impedance is used, the driving electrode TX has a large voltage change rate in the first stage, which can easily interfere with the display of the screen 30, causing a water ripple problem with alternating bright and dark intervals on the screen 30. This application provides a driving circuit 100 with dynamically adjusted driving impedance, which reduces the voltage change rate of the driving electrode TX without significantly increasing the charging time. Furthermore, as... Figure 9 As shown, the driving electrode TX has a relatively consistent voltage change rate from the first stage to the fifth stage, which can reduce the interference of the driving electrode TX voltage on the display screen and improve or even eliminate display abnormalities that can be perceived by the human eye.

[0085] In the sixth stage (from time t5 to time t6), the voltage of the driving electrode TX is 0. For example, control signals ZN1-ZN5 are low, and control signals ZP1-ZP5 are low.

[0086] In the seventh stage (from time t6 to time t7), control signals L1-L5 are low, control signals ZN1-ZN5 are low, control signal LN is high, control signal HN is low, control signal H1 is low, control signals H2-H5 are high, and control signals ZP1-ZP5 are low. The first control switch P31 is turned on, the first charging switch P11 is turned on, and the first terminal N1 provides positive charge to the driving electrode TX through the first charging switch P11, charging the driving electrode TX from 0 to the fifth intermediate voltage.

[0087] In the eighth stage (from time t7 to time t8), control signals L1-L5 are low, control signals ZN1-ZN5 are low, control signal LN is high, control signal HN is low, control signals H1-H2 are low, control signals H3-H5 are high, and control signals ZP1-ZP5 are low. The first control switches P31-P32 are turned on, and the first charging switches P11-P12 are turned on. The first terminal N1 provides positive charge to the driving electrode TX through the first charging switches P11-P12, charging the driving electrode TX from the fifth intermediate voltage to the sixth intermediate voltage.

[0088] In the ninth stage (from time t8 to time t9), control signals L1-L5 are low, control signals ZN1-ZN5 are low, control signal LN is high, control signal HN is low, control signals H1-H3 are low, control signals H4-H5 are high, and control signals ZP1-ZP5 are low. The first control switches P31-P33 are turned on, and the first charging switches P11-P13 are turned on. The first terminal N1 provides positive charge to the driving electrode TX through the first charging switches P11-P13, charging the driving electrode TX from the sixth intermediate voltage to the seventh intermediate voltage.

[0089] In the tenth stage (from time t9 to time t10), control signals L1-L5 are low, control signals ZN1-ZN5 are low, control signal LN is high, control signal HN is low, control signals H1-H4 are low, control signal H5 is high, and control signals ZP1-ZP5 are low. The first control switches P31-P34 and the first charging switches P11-P14 are turned on. The first terminal N1 provides positive charge to the driving electrode TX through the first charging switches P11-P14, charging the driving electrode TX from the seventh intermediate voltage to the eighth intermediate voltage.

[0090] In the eleventh stage (from time t10 to time t11), control signals L1-L5 are low, control signals ZN1-ZN5 are low, control signal LN is high, control signal HN is low, control signals H1-H5 are low, and control signals ZP1-ZP5 are low. The first control switches P31-P35 are turned on, and the first charging switches P11-P15 are turned on. The first terminal N1 provides positive charge to the driving electrode TX through the first charging switches P11-P15, charging the driving electrode TX from the eighth intermediate voltage to the first target voltage PV.

[0091] During the process of charging the voltage of the driving electrode TX from 0V to the first target voltage PV, the number of the first charging switches P11-P15 that are turned on are 1, 2, 3, 4, and 5 respectively, and the driving impedance of the driving circuit 100 gradually decreases. In contrast, Figure 9 The dashed line in the diagram represents the voltage of the driving electrode TX when the driving circuit 100 uses a fixed driving impedance. The first charging switches P11-P15 of the driving circuit 100 are in the ON state from stage 7 to stage 11, and the driving circuit 100 has a fixed driving impedance. The first terminal N1 charges the driving electrode TX through the first charging switches P11-P15, and the driving electrode TX is charged to PV at time t101. Figure 9 As shown, if a small fixed driving impedance is used, the driving electrode TX has a large voltage change rate in the seventh stage, which can easily interfere with the display of the screen 30, causing a water ripple problem with alternating bright and dark intervals on the screen 30. This application provides a driving circuit 100 with dynamically adjusted driving impedance, which reduces the voltage change rate of the driving electrode TX without significantly increasing the charging time. Furthermore, as... Figure 9 As shown, the driving electrode TX has a relatively consistent voltage change rate from the seventh stage to the eleventh stage, which can reduce the interference of the driving electrode TX voltage on the display screen and improve or even eliminate display abnormalities that can be perceived by the human eye.

[0092] In summary, during the systematic charging of the driving electrode TX from the second target voltage NV to 0V, the number of activated second charging switches N21-N25 gradually increases, and the driving impedance of the driving circuit 100 gradually decreases. Conversely, during the charging of the driving electrode TX from 0V to the first target voltage PV at the first terminal N1, the number of activated first charging switches P11-P15 gradually increases, and the driving impedance of the driving circuit 100 gradually decreases. By dynamically adjusting the number of activated first and second charging switches, the driving impedance of the driving circuit is dynamically adjusted, ensuring that the voltage change rate of the driving electrode TX is not excessive and that the voltage change rate of the driving electrode TX has a consistent rate throughout the charging process. This reduces the interference of the driving electrode TX voltage on the display image and improves or even eliminates display abnormalities perceptible to the human eye.

[0093] The reason for dividing the charging process of the driving electrode TX into two parts is as follows: If the driving electrode TX is charged using the first terminal N1 when its voltage is at the second target voltage NV, the voltage difference across the first charging switch will be too large, resulting in an excessively large charging current and an excessively large voltage change rate for the driving electrode TX, which will interfere with the display screen 30. By systematically charging the driving electrode TX, the excessively large voltage change rate of the driving electrode TX in the initial stage of the charging process can be avoided. It can be understood that the charging process of the driving electrode TX can also be divided into: a process from the second target voltage NV to the first voltage, a process from the first voltage to the second voltage, and a process from the second voltage to the first target voltage PV. In each process, the driving impedance of the driving circuit 100 is dynamically adjusted by adjusting the number of conducting charging switches, so that the voltage change rate of the driving electrode TX has a consistent rate throughout the entire charging process.

[0094] The process by which the driving circuit 100 discharges the driving electrode TX from the first target voltage PV to the second target voltage NV is similar to the charging process described above. For example... Figure 9As shown, from time t12 to time t13, the driving electrode TX discharges from the first target voltage PV to 0V; from time t14 to time t15, the driving electrode TX discharges from 0V to the second target voltage NV. Specifically, from time t12 to time t13, there are five stages: the second discharge switches P21-P25 are turned on sequentially, the number of turned-on second discharge switches P21-P25 gradually increases, and the driving impedance of the driving circuit 100 decreases sequentially; from time t14 to time t15, the first discharge switches N11-N15 are turned on sequentially, the number of turned-on first discharge switches N11-N15 gradually increases, and the driving impedance of the driving circuit 100 decreases sequentially. During the process of the driving electrode TX discharging from the first target voltage PV to 0V (i.e., from time t12 to time t13), the control signal HN causes the second charging switches N21-N25 to be turned off, preventing the output terminal OUT from being connected via the path from the first control switch to the second charging switch to the system ground.

[0095] exist Figure 8-9 In the illustrated embodiment, the charging process of the driving electrode TX is divided into two processes. In each process, the number of conducting charging switches gradually increases, and the driving impedance of the driving circuit 100 gradually decreases. Similarly, the discharging process of the driving electrode TX is divided into two processes. In each process, the number of conducting discharging switches gradually increases, and the driving impedance of the driving circuit 100 gradually decreases. Therefore, during the charging and discharging processes of the driving electrode TX, excessive voltage change rate of the driving electrode TX is avoided, and a relatively consistent voltage change rate is achieved.

[0096] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A driving circuit, characterized in that, Applied to a touch screen, the touch screen includes driving electrodes, and the driving circuit includes: The first terminal is used to provide a first target voltage; The output terminal is configured to be connected to the driving electrode; and Multiple first charging switches are connected in parallel between the first terminal and the output terminal; The first terminal is used to charge the driving electrode to the first target voltage, and during the process of charging the driving electrode to the first target voltage, the number of the first charging switches that are turned on gradually increases.

2. The driving circuit according to claim 1, characterized in that, The first charging switch is a PMOS transistor.

3. The driving circuit according to claim 1, characterized in that, The process of charging the driving electrode to the first target voltage includes a first stage and a second stage that occur sequentially, wherein the driving impedance of the driving circuit in the second stage is less than the driving impedance of the driving circuit in the first stage.

4. The driving circuit according to claim 1, characterized in that, The process of charging the driving electrode to the first target voltage includes a first stage, a second stage, and a third stage that occur sequentially. In the third stage, the driving impedance of the driving circuit is less than the driving impedance of the driving circuit in the second stage, and the driving impedance of the driving circuit in the second stage is less than the driving impedance of the driving circuit in the first stage.

5. The driving circuit according to claim 1, characterized in that, The driving circuit also includes: The second terminal is used to provide a second target voltage, which is less than the first target voltage; and Multiple first discharge switches are connected in parallel between the second terminal and the output terminal; The second terminal is used to discharge the driving electrode to the second target voltage. During the process of discharging the driving electrode to the second target voltage, the number of the first discharge switches that are turned on gradually increases.

6. The driving circuit according to claim 5, characterized in that, The second target voltage is a negative voltage.

7. The driving circuit according to claim 5, characterized in that, The first discharge switch is an NMOS transistor.

8. The driving circuit according to claim 6, characterized in that, The driving circuit also includes: Systematic; and A plurality of second charging switches are connected in parallel between the system ground and the output terminal; Specifically, the system is used to charge the driving electrode from the second target voltage to the ground voltage. During the process of systematically charging the driving electrode from the second target voltage to the ground voltage, the number of the second charging switches that are turned on gradually increases. During the process of charging the voltage of the driving electrode from the ground voltage to the first target voltage at the first terminal, the number of the first charging switches that are turned on gradually increases.

9. The driving circuit according to claim 8, characterized in that, The driving circuit further includes: a plurality of first control switches; Each of the first charging switches and its corresponding first control switch are connected in series between the first terminal and the output terminal, and each of the second charging switches and its corresponding first control switch are connected in series between the system ground and the output terminal.

10. The driving circuit according to claim 9, characterized in that, The second charging switch is an NMOS transistor, and the first control switch is a PMOS transistor.

11. The driving circuit according to claim 8, characterized in that, The driving circuit further includes: a plurality of second discharge switches, wherein the plurality of second discharge switches are connected in parallel between the system ground and the output terminal; The system is further configured to discharge the driving electrode from the first target voltage to the ground voltage. During the process of discharging the driving electrode from the first target voltage to the ground voltage, the number of the second discharge switches that are turned on gradually increases. During the process of discharging the driving electrode from the ground voltage to the second target voltage at the second terminal, the number of the first discharge switches that are turned on gradually increases.

12. The driving circuit according to claim 11, characterized in that, The drive circuit further includes: a plurality of second control switches; Each of the first discharge switches and its corresponding second control switches are connected in series between the second terminal and the output terminal, and each of the second discharge switches and its corresponding second control switches are connected in series between the system ground and the output terminal.

13. The driving circuit according to claim 12, characterized in that, The second discharge switch is a PMOS transistor, and the second control switch is an NMOS transistor.

14. A touch chip, characterized in that, The device includes a driving circuit and a detection circuit according to any one of claims 1-13, wherein when the driving circuit provides a driving signal to the driving electrode, the detection circuit is used to receive a detection signal from the detection electrode.

15. An electronic device, characterized in that, Includes the touch chip and touch screen according to claim 14, wherein the touch chip is used to charge the driving electrodes in the touch screen.

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