Touch detection circuit, method, chip, and device

Abstract

This application provides a touch detection circuit, method, chip, and device. The touch detection circuit is electrically connected to a touch electrode, and a parasitic capacitance is formed between the touch electrode and ground. The touch detection circuit includes a capacitance neutralization circuit, an amplification circuit, and a reference voltage generation circuit. The capacitance neutralization circuit and the amplification circuit work together in the second stage of the scan cycle to neutralize the charge of the parasitic capacitance multiple times. In the third stage of the scan cycle, the operational amplifier obtains a charge change information based on the charge after the parasitic capacitance neutralization and the reference voltage provided by the reference voltage circuit. The change in charge change information is used to indicate the touch signal of the touch electrode. Therefore, the touch detection circuit, method, chip, and touch device provided by this application can reduce the manufacturing cost of touch chips and touch devices.

Description

[Technical Field]

[0001] This application relates to the field of touch control, and more specifically, to a touch detection circuit, method, chip, and device. [Previous Technology]

[0002] In touch devices, a self-capacitance detection scheme can be used to detect user touch operations. In the self-capacitance detection scheme, when a conductor approaches or touches the touch electrode in the touch device, the parasitic capacitance between the touch electrode and ground will change. By detecting the amount of change in parasitic capacitance between the touch electrode and ground, the user's touch position can be obtained. Since the parasitic capacitance between the touch electrode and ground is often relatively large, while the capacitance change caused by a conductor approaching or touching the detection electrode is relatively small, a neutralizing capacitor with a capacitance similar to the parasitic capacitance is needed to neutralize the original parasitic capacitance between the touch electrode and ground when there is no touch, thereby improving the detection accuracy of user touch.

[0003] However, since the parasitic capacitance between the touch electrode and ground is often relatively large, the capacitance, volume, and layout area of ​​the neutralizing capacitor also need to be set to be larger, which increases the manufacturing cost of the touch circuit. [Summary of the Invention]

[0004] In view of the above problems, this application provides a touch detection circuit, method, chip and device.

[0005] In its first aspect, this application provides a touch detection circuit electrically connected to a touch electrode, with a parasitic capacitance formed between the touch electrode and ground. The touch detection circuit includes: a capacitor neutralization circuit, including a switching circuit and an electrode conduction switch, the switching circuit including at least two neutralization capacitors; an amplifier circuit, including an operational amplifier, a feedback capacitor, and a feedback switch, the non-inverting input of the operational amplifier receiving a reference voltage, and the inverting input of the operational amplifier electrically connected to the output of the operational amplifier via the feedback capacitor; and a reference voltage generation circuit for outputting a reference voltage. In the first stage of the scan cycle of the touch electrode, the switching circuit, the electrode conduction switch, and the feedback switch cooperate to set the voltage of the touch electrode to the reference voltage, and in the second stage of the scan cycle, the neutralization capacitors repeatedly neutralize the charge of the parasitic capacitance and conduct the electrical connection between the touch electrode and the inverting input of the operational amplifier. In the third stage of the scan cycle, the operational amplifier obtains the charge change information based on the charge after the parasitic capacitance is neutralized and the reference voltage. The change in charge change information is used to indicate the touch information of the touch electrode.

[0006] In conjunction with the first state, in one possible implementation, at least two neutralizing capacitors include a first capacitor and a second capacitor, the switching circuit includes a first switching circuit and a second switching circuit, and the second stage within the scanning cycle includes a plurality of alternating charging and discharging stages. During the charging stage, the first switching circuit charges the first capacitor, and the second switching circuit discharges the second capacitor to the touch electrode, thereby neutralizing the parasitic capacitance charge in the second capacitor. During the discharging stage, the first switching circuit discharges the first capacitor to the touch electrode, thereby neutralizing the parasitic capacitance charge in the first capacitor, and the second switching circuit charges the second capacitor.

[0007] In conjunction with the first state, in one possible implementation, during the charging phase, the first switching circuit is used to cause the first capacitor to receive a preset charging voltage, thereby charging the first capacitor. During the discharging phase, the second switching circuit is used to cause the second capacitor to receive a charging voltage, thereby charging the second capacitor.

[0008] In conjunction with the first state, in one possible implementation, during the charging phase, the second switching circuit is configured to ensure that both ends of the second capacitor receive a reference voltage, thereby discharging the second capacitor to the touch electrode. During the discharging phase, the first switching circuit is configured to ensure that both ends of the first capacitor receive a reference voltage, thereby discharging the first capacitor to the touch electrode.

[0009] In conjunction with the first state, in one possible implementation, both the first and second switching circuits include a charging pull-up switch, a charging pull-down switch, and a discharging on switch. The first terminals of the first and second capacitors respectively receive a high charging voltage via the charging pull-up switches of the first and second switching circuits, and are respectively electrically connected to the touch electrode via the discharging on switches of the first and second switching circuits. The second terminals of the first and second capacitors respectively receive a low charging voltage via the charging pull-down switches of the first and second switching circuits, and the voltage difference between the high and low charging voltages is a preset charging voltage. During the charging phase, the charging pull-up and charging pull-down switches of the first switching circuit are turned on, causing the first capacitor to charge, and the discharging on switch of the second switching circuit is turned on, causing the second capacitor to discharge to the touch electrode. During the discharging phase, the discharging on switch of the first switching circuit is turned on, causing the first capacitor to discharge to the touch electrode, and the charging pull-up and charging pull-down switches of the second switching circuit are turned on, causing the second capacitor to charge.

[0010] In conjunction with the first state, in one possible implementation, an electrode on / off switch is electrically connected between the touch electrode and the inverting input terminal of the operational amplifier, and a feedback switch is electrically connected between the inverting input terminal and the output terminal of the operational amplifier. In the first stage, the electrode on / off switch and the feedback switch are on to set the voltage of the touch electrode to a reference voltage. In the second stage, the electrode on / off switch is on and the feedback switch is off, thereby establishing the electrical connection between the touch electrode and the inverting input terminal of the operational amplifier.

[0011] In conjunction with the first state, in one possible implementation, both the first and second switching circuits further include a reference voltage switch. The second terminals of the first and second capacitors respectively receive reference voltages via the reference voltage switches of the first and second switching circuits. During the charging phase, the reference voltage switch of the second switching circuit is turned on, so that the voltage across the second capacitor is the reference voltage, thereby discharging the second capacitor to the touch electrode. During the discharging phase, the reference voltage switch of the first switching circuit is turned on, so that the voltage across the first capacitor is the reference voltage, thereby discharging the first capacitor to the touch electrode.

[0012] In the second aspect, this application provides a touch detection method applied to a touch detection circuit provided in any possible implementation of the first aspect. The method includes: in a first stage within a scanning cycle of the touch electrode, setting the voltage of the touch electrode to a reference voltage; in a second stage within the scanning cycle, causing a neutralizing capacitor to repeatedly neutralize the charge of a parasitic capacitor and connecting the touch electrode to the inverting input of an operational amplifier; and in a third stage within the scanning cycle, obtaining a charge change information based on the charge after neutralization of the parasitic capacitor and the reference voltage, wherein the change in the charge change information is used to indicate the touch message of the touch electrode.

[0013] In the third state, this application provides a touch chip, including an arithmetic circuit and a touch detection circuit provided in any possible implementation of the first state. The arithmetic circuit is used to convert the change in charge information into a digital signal, and output an indication signal according to the digital signal. The indication signal is used to indicate the touch information of the touch electrode.

[0014] In the fourth state, this application provides a touch device, including a touch panel and a touch chip provided in any possible implementation of the third state. The touch panel includes touch electrodes, and the touch chip is used to detect touch information of the touch electrodes.

[0015] Therefore, the touch detection circuit, method, chip and touch device provided in this application can continuously charge and discharge at least two neutralizing capacitors during the scanning cycle of the touch electrode, and neutralize the parasitic capacitive charge of the touch electrode by means of feedback capacitor, which can reduce the manufacturing cost of touch chip and touch device.

Implementation Method

[0017] The technical solutions in the embodiments of this application will be clearly described below with reference to the accompanying drawings.

[0018] It is understood that the connection relationship described in this application refers to a direct or indirect connection. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components. For example, A can be directly connected to C, and C can be directly connected to B, thereby achieving a connection between A and B through C. It is also understood that the "A connects to B" described in this application can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.

[0019] In the description of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "AND / OR" in this document is merely a description of the relationship between related objects, indicating that there are three kinds of relationships. For example, A AND / OR B can mean: existing only in A, existing in both A and B, or existing only in B.

[0020] In the description of this application, the words "first," "second," etc., are used only to distinguish different objects and do not limit the quantity or order of execution, and the words "first," "second," etc., are not necessarily different. In addition, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0021] Please refer to Figure 1, which is a schematic diagram of a touch device 10 provided in an embodiment of this application.

[0022] The touch device 10 includes a touch panel 11 and a touch chip 12. The touch panel 11 includes n touch electrodes S1-Sn. Each touch electrode S1-Sn has a parasitic capacitance Crx1-Crxn between itself and ground. The touch electrodes S1-Sn are all electrically connected to the touch chip 12.

[0023] When the touch panel 11 receives a touch operation, the parasitic capacitances Crx1-Crxn corresponding to the touched touch electrodes S1-Sn will change. The touch chip 12 can obtain the touch information of the touch electrodes S1-Sn based on the change in the parasitic capacitances Crx1-Crxn corresponding to the touch electrodes S1-Sn. For example, whether the touch electrodes S1-Sn are touched, and the specific location of the touched touch electrodes S1-Sn, etc.

[0024] As shown in Figure 2, the touch chip 12 includes a touch detection circuit and an arithmetic circuit 123. The touch detection circuit includes a capacitor neutralization circuit 1211 and an amplifier circuit 1212. The touch electrode S1 is electrically connected to the capacitor neutralization circuit 1211.

[0025] The capacitor neutralization circuit 1211 and the amplifier circuit 1212 work together to neutralize the charge of the corresponding parasitic capacitor Crx1 multiple times during the scanning cycle of the touch electrode S1.

[0026] The amplifier circuit 1212 is also used to obtain charge change information based on the amount of charge after neutralization output from the touch electrode S1 and the preset reference voltage VREF.

[0027] The operational circuit 123 converts the charge change information into a corresponding digital signal. This avoids measuring the absolute value of the charge information, simplifying circuit design, reducing complexity, and lowering power consumption, compared to generating a corresponding digital signal based on the charge information. Simultaneously, it eliminates the need for calibration or adjustment of the circuit to eliminate the initial bias voltage of the operational amplifier CA in the touch detection circuit 121, improving detection reliability. Furthermore, even when the touch device 10 is interfered with, the charge change information can still accurately reflect the actual touch information of the touch electrode S1, enhancing the robustness of touch detection.

[0028] The arithmetic circuit 123 is also used to perform digital processing on the digital signal to obtain the touch information of the touch electrode S1. Specifically, when the touch electrode S1 is not touched, since the parasitic capacitance Crx1 corresponding to the touch electrode S1 does not change, the change in charge output by the touch electrode S1 is zero, and the change in charge change information will not change either. Therefore, the corresponding digital signal will not change, and the arithmetic circuit 123 can determine that the touch electrode S1 has not been touched based on the unchanged digital signal. When the touch electrode S1 is touched, the parasitic capacitance Crx1 corresponding to the touch electrode S1 is superimposed with the equivalent capacitance of the touch conductor, so the change in charge output by the touch electrode S1 is not zero, and the change in charge change information will change. Therefore, the corresponding digital signal will also change, and the arithmetic circuit 123 can determine that the touch electrode S1 has not been touched based on the changed digital signal.

[0029] Please refer to Figure 3, which shows a circuit diagram of the touch detection circuit 121 provided in this application. The touch detection circuit 121 includes a capacitor neutralization circuit 1211, an amplifier circuit 1212, and a reference voltage generation circuit 1213. The capacitor neutralization circuit 1211 includes a switching circuit and an electrode conduction switch P2. The amplifier circuit 1212 includes an operational amplifier CA, a feedback capacitor CF, and a feedback switch P1. The switching circuit includes a first switching circuit and a second switching circuit.

[0030] The capacitor neutralization circuit 1211 is electrically connected to the touch electrode S1 via a switching circuit. The touch electrode S1 is electrically connected to the amplifier circuit 1212 via an electrode conduction switch P2. The reference voltage generation circuit 1213 is electrically connected to the amplifier circuit 1212. The reference voltage generation circuit 1213 is also electrically connected to the capacitor neutralization circuit 1211 via a switching circuit.

[0031] During the first stage of the scanning cycle of the touch electrode S1, the switching circuit, the electrode conduction switch P2 and the feedback switch P1 cooperate with each other to set the voltage of the touch electrode S1 to the reference voltage VREF.

[0032] In the second stage of the scanning cycle, the switching circuit, electrode conduction switch P2 and feedback switch P1 cooperate with each other to neutralize the charge of parasitic capacitor Crx1 multiple times, and are used to conduct the electrical connection between touch electrode S1 and amplifier circuit 1212.

[0033] In the third stage of the scanning cycle, the amplifier circuit 1212 is used to obtain charge change information based on the charge neutralized by the parasitic capacitance Crx1 and the reference voltage VREF provided by the reference voltage generation circuit 1213. The charge change information is used to indicate the touch information of the touch electrode S1.

[0034] Specifically, the switching circuit includes two neutralizing capacitors, namely a first capacitor CB1 and a second capacitor CB2. The switching circuit also includes a first switching circuit and a second switching circuit. The first switching circuit includes charging pull-up switches P3A and P3B, charging pull-down switches P5A and P5B, discharging conduction switches P4A and P4B, and reference voltage switches P6A and P6B. The second switching circuit includes charging pull-up switches P3A and P3B, charging pull-down switches P5A and P5B, discharging conduction switches P4A and P4B, and reference voltage switches P6A and P6B.

[0035] The first terminals of the first capacitor CB1 and the second capacitor CB2 respectively receive charging high voltage through charging pull-up switch P3A and charging pull-up switch P3B, and are respectively electrically connected to the touch electrode S1 through discharge conduction switch P4A and discharge conduction switch P4B.

[0036] The second terminals of the first capacitor CB1 and the second capacitor CB2 respectively receive the low charging voltage via charging pull-down switches P5A and P5B, and are respectively electrically connected to the reference voltage generation circuit 1213 via reference voltage switches P6A and P6B ​​to receive the reference voltage VREF generated therefrom. The voltage difference between the high charging voltage and the low charging voltage is a preset charging voltage.

[0037] Electrode on switch P2 is electrically connected between touch electrode S1 and the inverting input terminal of operational amplifier CA, and feedback switch P1 is electrically connected between the inverting input terminal and the output terminal of operational amplifier CA. The non-inverting input terminal of operational amplifier CA is electrically connected to reference voltage generation circuit 1213 to receive the reference voltage VREF generated therefrom.

[0038] In some embodiments, the capacitance values ​​of the first capacitor CB1 and the second capacitor CB2 may be the same or different. The following description takes the example that the capacitance values ​​of the first capacitor CB1 and the second capacitor CB2 are both CB. However, this application does not limit the capacitance values ​​of the first capacitor CB1 and the second capacitor CB2.

[0039] During the scanning cycle of the touch electrode S1, the touch electrode 12 can obtain touch information from the touch electrode S1. The scanning cycle of the touch electrode S1 includes multiple scanning cycles, each scanning cycle including a first stage, a second stage and a third stage.

[0040] The first stage is the reset stage. In this stage, the operational amplifier CA completes the reset, and the switching circuit, electrode on switch P2 and feedback switch P1 cooperate to set the voltage of the touch electrode S1 to the reference voltage VREF.

[0041] The second stage is the neutralization stage. In this stage, the switching circuit, electrode on switch P2, and feedback switch P1 cooperate to allow the neutralizing capacitor to neutralize the charge of the parasitic capacitor Crx1 multiple times. Thus, by setting a neutralization stage within the scanning cycle of the touch electrode S1, the switching circuit can cause the neutralizing capacitor to cycle through charging and discharging multiple times during the neutralization stage, thereby allowing the neutralizing capacitor to transfer charge to the parasitic capacitor Crx1 of the touch electrode S1 multiple times. This significantly reduces the capacitance, volume, and layout area of ​​the neutralizing capacitor, thereby reducing the manufacturing cost of the touch circuit.

[0042] Furthermore, in the second stage, the electrode switching switch P2 is turned on, thereby realizing the electrical connection between the touch electrode S1 and the inverting input terminal of the operational amplifier CA. In this way, the feedback capacitor CF can also buffer the charge output by the parasitic capacitor Crx1 in the second stage, increasing the speed at which the neutralizing capacitor transfers charge to the parasitic capacitor Crx1 of the touch electrode S1, thereby improving the touch detection efficiency of the touch electrode S1.

[0043] The third stage is the stabilization stage. In this stage, the neutralizing capacitor has completed multiple neutralizations of the parasitic capacitor Crx1, and the voltages of the touch electrode S1, the first capacitor CB1, the second capacitor CB2, and the feedback capacitor CF gradually stabilize. The operational amplifier CA obtains the charge change information based on the charge after neutralization of the parasitic capacitor Crx1 and the reference voltage VREF. The operational circuit 123 then obtains the touch information of the touch electrode S1 based on the change in the charge change information.

[0044] Based on the circuit structure of the touch detection circuit 121, the scanning wheel of the touch electrode S1 will be specifically described below.

[0045] Please refer to Figure 4, which is a schematic diagram of the scanning wheel of the touch electrode S1 provided in an embodiment of this application. One frame of touch detection time period of the touch panel 11 includes multiple scanning wheels of touch electrodes S1-Sn, with each touch electrode S1-Sn scanning wheel performed sequentially. That is, one frame of touch detection time period of the touch panel 11 starts with the scanning wheel of touch electrode S1 and ends with the scanning wheel of touch electrode Sn. During each scanning wheel phase of touch electrodes S1-Sn, the touch electrode 12 can obtain the touch information of the corresponding touch electrode S1-Sn. Therefore, when the scanning wheel of touch electrode Sn ends, one frame of touch detection time period of the touch panel 11 ends, and the touch electrode 12 can obtain the touch information of all touch electrodes S1-Sn, thereby determining whether the touch panel 11 has received a touch operation, and the specific touch electrode S1-Sn that received the touch operation, thus enabling precise positioning of the touch location.

[0046] Taking the S1 scanning wheel as an example, the S1 scanning wheel includes multiple S1 scanning cycles. Within each S1 scanning cycle, the operational amplifier CA can output corresponding charge change information based on the parasitic capacitance Crx1 of the touch electrode S1. When the touch electrode S1 receives a touch operation, the parasitic capacitance Crx1 of the touch electrode S1 will change, and the charge change information output by the operational amplifier CA will also change. Therefore, the arithmetic circuit 123 can convert the change in charge change information ΔCAOUT output by the operational amplifier CA into a corresponding digital signal and perform subsequent digital processing. After the arithmetic circuit 123 performs digital processing on the digital signal, it can obtain the touch information of the touch electrode S1.

[0047] Specifically, an S1 scan cycle includes a reset phase, a neutralization phase, and a stabilization phase, which are the first, second, and third phases of the scan cycle, respectively.

[0048] During the reset phase, both feedback switch P1 and electrode on switch P2 are turned on. At this time, operational amplifier CA operates in negative feedback mode, thereby satisfying the virtual short condition. Therefore, the voltage at the inverting input terminal of operational amplifier CA is the same as the voltage at the non-inverting output terminal, both being the reference voltage VREF. Since the touch electrode S1 is electrically connected to the inverting input terminal of operational amplifier CA, the voltage of touch electrode S1 can be set to the reference voltage VREF by both feedback switch P1 and electrode on switch P2 being turned on.

[0049] In this embodiment, the reference voltage VREF output by the reference voltage generation circuit 1213 is a first preset voltage VREF1 during the reset phase, gradually increases during the neutralization phase, and reaches and maintains a second preset voltage VREF2 during the stabilization phase. The second preset voltage VREF2 is greater than the first preset voltage VREF1. Therefore, during the reset phase, the parasitic capacitor Crx1 is charged, and the voltage of the touch electrode S1 is set to the first preset voltage VREF1.

[0050] The neutralization phase includes multiple alternating charging and discharging phases corresponding to each neutralizing capacitor. Each adjacent charging and discharging phase constitutes a charge-discharge cycle. As shown in Figure 4, the neutralization phase includes six charge-discharge cycles of the first capacitor CB1 and five charge-discharge cycles of the second capacitor CB2. The charge-discharge cycle of the first capacitor CB1 will be used as an example for explanation. The charge-discharge cycle of the second capacitor CB2 is similar to that of the first capacitor CB1 and will not be described further here.

[0051] During the charging phase of the first capacitor CB1, the feedback switch P1 is open, and the electrode conduction switch P2 is open. The charging pull-up switch P3A and the charging pull-down switch P5A are open, while the discharging conduction switch P4A and the reference voltage switch P6A are open. This allows the first terminal of the first capacitor CB1 to receive a high charging voltage via the charging pull-up switch P3A, and the second terminal of the first capacitor CB1 to receive a low charging voltage via the charging pull-down switch P5A, thereby charging the first capacitor CB1. The voltage difference between the high charging voltage and the low charging voltage is the preset charging voltage.

[0052] When the first capacitor CB1 is fully charged, the charge on the first capacitor CB1 is Q1 = CB1 × (VRH - VRL), where CB1 is the capacitance of the first capacitor CB1, VRH is the high charging voltage, and VRL is the low charging voltage.

[0053] Simultaneously, the charging phase of the first capacitor CB1 can also be the discharging phase of the second capacitor CB2. That is, during the charging phase of the first capacitor CB1, the charging pull-up switch P3B and the charging pull-down switch P5B are open, while the discharging switch P4B and the reference voltage switch P6B are closed, so that the first terminal of the second capacitor CB2 is electrically connected to the inverting input terminal of the operational amplifier CA, and the second terminal of the second capacitor CB2 receives the reference voltage VREF. Due to the virtual short principle of the operational amplifier CA, the voltage at the inverting input terminal of the operational amplifier CA is also the reference voltage VREF. At this time, the voltages across the second capacitor CB2 are both the reference voltage VREF. After the charging phase of the second capacitor CB2 in the previous cycle is completed, the charge on the second capacitor CB2 is transferred to the parasitic capacitor Crx1 during the discharging phase of the second capacitor CB2. Furthermore, because the electrode switching switch P2 is on, the feedback capacitor CF can also absorb some of the charge of the parasitic capacitor Crx1 as a buffer, thereby accelerating the neutralization of the charge of the parasitic capacitor Crx1 by the first capacitor CB1 and the second capacitor CB2, and improving the touch detection speed of the touch electrode S1. Because the reference voltage VREF changes, the on-state switch P2 can also effectively prevent the voltage change at the second terminals of the first capacitor CB1 and the second capacitor CB2 from changing too quickly, which could lead to overshoot at the first terminals of the first capacitor CB1 and the second capacitor CB2 and cause leakage.

[0054] Similarly, during the discharge phase of the first capacitor CB1, the feedback switch P1 is open, and the electrode conduction switch P2 is on. The charging pull-up switch P3A and the charging pull-down switch P5A are open, while the discharge conduction switch P4A and the reference voltage switch P6A are on, thereby electrically connecting the first terminal of the first capacitor CB1 to the inverting input terminal of the operational amplifier CA, and the second terminal of the first capacitor CB1 receives the reference voltage VREF. At this time, the voltage across the first capacitor CB1 is the reference voltage VREF. The charge on the first capacitor CB1 is transferred to the parasitic capacitor Crx1 during its discharge phase. In each charge and discharge cycle of the first capacitor CB1, the amount of charge transferred from the first capacitor CB1 to the parasitic capacitor Crx1 is Q1 = CB1 × (VRH - VRL).

[0055] During the neutralization phase, the voltage of the touch electrode S1 changes with the reference voltage VREF, that is, the trend of the voltage change of the touch electrode S1 is the same as the trend of the reference voltage VREF.

[0056] Thus, the charging phase of the first capacitor CB1 and the discharging phase of the second capacitor CB2 coincide in time, and the discharging phase of the first capacitor CB1 and the charging phase of the second capacitor CB2 coincide in time. That is, when the first capacitor CB1 is charging, the second capacitor CB2 discharges to the touch electrode S1, thereby neutralizing the charge of the parasitic capacitor Crx1. When the first capacitor CB1 discharges to the touch electrode S1, thereby neutralizing the charge of the parasitic capacitor Crx1, the second capacitor CB2 is charging. This cycle repeats, with the first capacitor CB1 and the second capacitor CB2 alternating multiple times to neutralize the charge of the parasitic capacitor Crx1. No additional waiting time needs to be set within the scanning cycle of the touch electrode S1 to wait for the first capacitor CB1 or the second capacitor CB2 to complete charging, which saves the scanning time of the touch electrode S1 and improves the touch detection efficiency of the touch electrode S1.

[0057] During the stabilization phase, the first capacitor CB1 and the second capacitor CB2 neutralize the charge of the parasitic capacitor Crx1, and the charging pull-up switches P3A and P3B, and the charging pull-down switches P5A and P5B are all disconnected. At this time, the reference voltage VREF stabilizes at the second preset voltage VREF2. The voltage of the touch electrode S1 also stabilizes at the second preset voltage VREF2. During the stabilization phase, because the first capacitor CB1 and the second capacitor CB2 have already neutralized the charge of the parasitic capacitor Crx1 multiple times during the neutralization phase, the charge change information CAOUT output by the operational amplifier CA will not be oversaturated.

[0058] The charge change information CAOUT output by the operational amplifier CA satisfies the following formula (1). The change in charge information ΔCAOUT satisfies the following formula (2).

[0059]

[0060] Therefore, ΔCAOUT is proportional to the capacitance change ΔCrxk1 of the touch electrode S1, so the touch information of the touch electrode S1 can be detected by ΔCAOUT.

[0061] Please refer to Figure 5, which is a schematic diagram of a touch detection method provided in an embodiment of this application. The touch detection method can be applied to the touch detection circuit 121 provided in this application. Specifically, the touch detection circuit 121 may further include a control circuit. The touch detection method may include the following steps.

[0062] Step S51: In the first stage of the scanning cycle of the touch electrode S1, the voltage of the touch electrode S1 is set to the reference voltage VREF.

[0063] Step S52: In the second stage of the scan cycle, the neutralizing capacitor neutralizes the charge of the parasitic capacitor Crx1 multiple times, and conducts the electrical connection between the touch electrode S1 and the inverting input terminal of the operational amplifier CA.

[0064] Step S53: In the third stage of the scanning cycle, the charge change information is obtained based on the charge after neutralization of parasitic capacitance Crx1 and reference voltage VREF. The change in charge change information is used to indicate the touch information of touch electrode S1.

[0065] For detailed descriptions of each step, please refer to the functional descriptions of each part of the touch detection circuit 121 above, which will not be repeated here.

[0066] Therefore, the touch detection circuit, method, touch chip and touch device provided by this application can continuously charge and discharge by at least one neutralizing capacitor during the scanning cycle of the touch electrodes S1-Sn, and neutralize the parasitic capacitance Crx1 charge of the touch electrodes S1-Sn by the feedback capacitor CF. This can reduce the manufacturing cost of the touch chip 12 and the touch device 10, and is conducive to the miniaturization and integration of the touch device 10.

[0067] Those skilled in the art should recognize that the above embodiments are only used to illustrate this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the spirit and scope of this application shall fall within the scope of protection claimed by this application. [Simplified Explanation of the Diagram]

[0016] Figure 1 is a schematic diagram of a touch device provided in an embodiment of this application. Figure 2 is a schematic diagram of a touch chip provided in an embodiment of this application. Figure 3 is a schematic diagram of a touch detection circuit provided in an embodiment of this application. Figure 4 is a schematic diagram of a scanning wheel of a touch electrode provided in an embodiment of this application. Figure 5 is a schematic diagram of a touch detection method provided in an embodiment of this application.

Claims

1. A touch detection circuit, electrically connected to a touch electrode, wherein a parasitic capacitance is formed between the touch electrode and ground, the improvement being that the touch detection circuit comprises: A capacitor neutralization circuit includes a switching circuit and an electrode conduction switch, wherein the switching circuit includes at least two neutralization capacitors; an amplifier circuit includes an operational amplifier, a feedback capacitor, and a feedback switch, wherein the non-inverting input of the operational amplifier receives a reference voltage, and the inverting input of the operational amplifier is electrically connected to the output of the operational amplifier via the feedback capacitor; a reference voltage generation circuit is used to output the reference voltage; in the first stage of the scanning cycle of the touch electrode, the switching circuit, the electrode conduction switch, and the feedback switch cooperate to set the voltage of the touch electrode to the reference voltage, and in the second stage of the scanning cycle, the neutralization capacitors neutralize the charge of the parasitic capacitor multiple times, and conduct the electrical connection between the touch electrode and the inverting input of the operational amplifier; in the third stage of the scanning cycle, the operational amplifier obtains a charge change information based on the charge after neutralization of the parasitic capacitor and the reference voltage, and the change in the charge change information is used to indicate the touch message of the touch electrode.

2. The touch detection circuit as described in claim 1, wherein, The at least two neutralizing capacitors include a first capacitor and a second capacitor; the switching circuit includes a first switching circuit and a second switching circuit; the second stage within the scanning cycle includes a plurality of alternating charging and discharging stages; during the charging stage, the first switching circuit charges the first capacitor, and the second switching circuit discharges the second capacitor to the touch electrode, so that the second capacitor neutralizes the charge of the parasitic capacitance; during the discharging stage, the first switching circuit discharges the first capacitor to the touch electrode, so that the first capacitor neutralizes the charge of the parasitic capacitance, and the second switching circuit charges the second capacitor.

3. The touch detection circuit as described in claim 2, wherein: During the charging phase, the first switching circuit is configured to enable the first capacitor to receive a preset charging voltage, thereby charging the first capacitor; during the discharging phase, the second switching circuit is configured to enable the second capacitor to receive the charging voltage, thereby charging the second capacitor.

4. The touch detection circuit as described in claim 2, wherein: During the charging phase, the second switching circuit is configured to ensure that both ends of the second capacitor receive the reference voltage, so that the second capacitor discharges to the touch electrode; during the discharging phase, the first switching circuit is configured to ensure that both ends of the first capacitor receive the reference voltage, so that the first capacitor discharges to the touch electrode.

5. The touch detection circuit as described in claim 2, wherein, Both the first and second switching circuits include a charging pull-up switch, a charging pull-down switch, and a discharging on switch. The first terminals of the first and second capacitors respectively receive a high charging voltage via the charging pull-up switches of the first and second switching circuits, and are respectively electrically connected to the touch electrode via the discharging on switches of the first and second switching circuits. The second terminals of the first and second capacitors respectively receive a low charging voltage via the charging pull-down switches of the first and second switching circuits, and the voltage difference between the high and low charging voltages is a preset charging voltage. During the charging phase, the charging pull-up and charging pull-down switches of the first switching circuit are turned on to charge the first capacitor, and the discharging on switch of the second switching circuit is turned on to discharge the second capacitor to the touch electrode. During the discharging phase, the discharging on switch of the first switching circuit is turned on to discharge the first capacitor to the touch electrode, and the charging pull-up and charging pull-down switches of the second switching circuit are turned on to charge the second capacitor.

6. The touch detection circuit as described in claim 5, wherein, The electrode on / off switch is electrically connected between the touch electrode and the inverting input terminal of the operational amplifier, and the feedback switch is electrically connected between the inverting input terminal and the output terminal of the operational amplifier. In the first stage, the electrode on / off switch and the feedback switch are turned on to set the voltage of the touch electrode to the reference voltage. In the second stage, the electrode on / off switch is turned on and the feedback switch is turned off, so that the electrical connection between the touch electrode and the inverting input terminal of the operational amplifier is established.

7. The touch detection circuit as described in claim 6, wherein, Both the first and second switching circuits further include a reference voltage switch; the second terminals of the first and second capacitors respectively receive the reference voltage via the reference voltage switches of the first and second switching circuits; during the charging phase, the reference voltage switch of the second switching circuit is turned on, so that the voltage across the second capacitor is the reference voltage, thereby discharging the second capacitor to the touch electrode; during the discharging phase, the reference voltage switch of the first switching circuit is turned on, so that the voltage across the first capacitor is the reference voltage, thereby discharging the first capacitor to the touch electrode.

8. A touch detection method applied to a touch detection circuit as described in any one of claims 1 to 7, the improvement being that the method comprises: During the first phase of the scanning cycle of the touch electrode, the voltage of the touch electrode is set to the reference voltage; In the second phase of the scan cycle, the neutralizing capacitor neutralizes the charge of the parasitic capacitor multiple times and connects the touch electrode to the inverting input of the operational amplifier. In the third phase of the scan cycle, a charge change information is obtained based on the charge after neutralization of the parasitic capacitor and the reference voltage. The change in the charge change information is used to indicate the touch message of the touch electrode.

9. A touch chip, improved in that it includes an arithmetic circuit and a touch detection circuit as described in any one of claims 1 to 7; the arithmetic circuit is used to convert the change in the charge change information into a digital signal, and output an indication signal according to the digital signal, the indication signal being used to indicate the touch information of the touch electrode.

10. A touch device, improved in that it includes a touch panel and a touch chip as described in claim 9, the touch panel including touch electrodes, and the touch chip for detecting touch information of the touch electrodes.

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