Capacitive touch sensing module and method

Abstract

The present invention discloses a capacitive touch sensing module and method. The module includes a capacitor amplifier circuit, a capacitor integration circuit, a switching circuit, and a detection control circuit. The detection control circuit controls the capacitor touch sensing module to alternately switch between a sampling integration state and an amplification transfer state by controlling the state of the switching circuit. In the sampling integration state, the capacitor amplifier circuit collects the charge signal on the touch key and the capacitor integration circuit generates an integrated accumulated voltage. In the amplification transfer state, the capacitor amplifier circuit amplifies the collected charge signal and the capacitor integration circuit transfers the charge signal amplified by the capacitor amplifier circuit. The detection control circuit is also used to record the number of integrations at this time when the output voltage of the capacitor integration circuit reaches a threshold voltage. If the number of integrations is less than a preset number, it is determined that the key is touched. The present invention does not require an external capacitor, and all components required for the circuit can be internally integrated.

Description

Technical Field

[0001] The present invention relates to the field of analog integrated circuit design, and in particular to a capacitive touch sensing module and method. Background Art

[0002] In recent years, with the rise of smartphones and tablets, the capacitive touchscreen market has experienced rapid growth. Analysts predict that capacitive touchscreens will play an increasingly important role not only in smartphones and tablets, but also in the future home appliance market. With the trend toward circuit integration, more and more discrete circuits are being integrated into chips, both standalone touch control chips and those integrated into microcontrollers (MCUs). MCU chips are microcontrollers that control peripherals based on user needs. Their low price and simple, fast productization have made them a mainstream product, with most home appliances using MCU chips. To meet market application demands, integrating capacitive touch sensing circuits into MCU chips is an inevitable trend.

[0003] At present, capacitive touch screens realize detection by transferring charge between capacitors. The specific principle is as follows: Figure 1 As shown in the figure, this is a touch detection module circuit. It consists of four components: key pins key1 through keyn, sampling capacitor pin Cs_pad, initialization level circuit, and voltage threshold detection. In the figure, Ck is the sum of the parasitic and stray capacitance of the key pin, and Cs is the external capacitance of the sampling capacitor pin. Cs is typically in the nF range, and Ck is in the pF range. This module supports two touch detection modes: charge detection and discharge detection.

[0004] The following uses charging detection and initializing the sampling capacitor to 0V as an example to explain the principle of touch button detection:

[0005] 1) Configuration: Enable the voltage threshold detection circuit and configure the voltage threshold to be detected. Preset the count of an MCU counter, save it, and then clear the counter.

[0006] 2) Initialization of sampling capacitor Cs: Close switches s_cs and s_gnd to discharge the residual charge on Cs and the bus through the ground line. After Cs is initialized, proceed to step 2);

[0007] 3) Initialize the key capacitor Ck: disconnect s_cs and s_gnd, close s_vcc and s1, and charge Ck1 to the Vcc level. After Ck initialization is completed, proceed to step 4);

[0008] 4) Charge Transfer: Disconnect s_vcc and then close s_cs to transfer the charge from Ck to Cs. Simultaneously, the MCU's internal counter increases by 1. During this period, if the Cs level reaches the voltage detection threshold, the voltage threshold detection circuit generates an interrupt signal to the MCU. If no interrupt signal is generated, proceed to step 3). If an interrupt signal is generated, proceed to step 5).

[0009] 5) Count Comparison: When the MCU receives an interrupt signal, it stops the counter and compares the current count value with the previously set count value. If the value is greater, the key has not been pressed, and the process returns to step 3) to test the next key. If the value is less, the key has been pressed, and testing ends.

[0010] The above-mentioned capacitive touch detection has a disadvantage, which is that it requires an external nF-level capacitor and reserves pins for the external capacitor. This not only takes up extra space on the PCB board, but also increases the cost of the application. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide a capacitive touch sensing module and method to address the defects of the prior art in that an external nF capacitor is required and pins for the external capacitor must be reserved.

[0012] The technical solution adopted by the present invention to solve the technical problem is to construct a capacitive touch sensing module, including:

[0013] a capacitance amplifying circuit, connected to at least one touch key module, for sensing capacitance introduced when the touch key is touched;

[0014] a capacitance integration circuit connected to the capacitance amplification circuit;

[0015] a switch circuit, comprising a plurality of switches distributed in the at least one touch key module, the capacitance amplifying circuit, and the capacitance integrating circuit, for controlling the states of the at least one touch key module, the capacitance amplifying circuit, and the capacitance integrating circuit by changing switch states;

[0016] a detection control circuit connected to the switch circuit and the capacitive integration circuit, configured to select a specific touch key module for detection by controlling the state of the switch circuit, and to control the capacitive touch sensing module to alternately switch between a sampling integration state and an amplification transfer state during the process of selecting the specific touch key module for detection, and to record the number of integrations when the output voltage of the capacitive integration circuit reaches a threshold voltage, and determine that the key is touched if the number of integrations is less than a preset number;

[0017] Among them, when in the sampling integration state, the capacitor amplifier circuit collects the charge signal on the touch button and the capacitor integration circuit generates an integrated accumulated voltage; when in the amplification transfer state, the capacitor amplifier circuit amplifies the collected charge signal and the capacitor integration circuit transfers the charge signal amplified by the capacitor amplifier circuit.

[0018] Preferably, each of the touch key modules includes a touch key, the capacitance amplification circuit includes an amplifier and an amplifying capacitor, the capacitance integration circuit includes an integrator, an integrating capacitor, and a charge transfer capacitor, and the switch circuit includes a first switch, a second switch, and an enabling switch, wherein: each of the touch key modules is distributed with a first switch, a second switch, and an enabling switch, the capacitance amplification circuit is distributed with two first switches and two second switches, and the capacitance integration circuit is distributed with one first switch;

[0019] The positive electrode of each touch key is connected to the power supply VDD via a first switch, and the positive electrode of each touch key is also connected to the out-of-phase input of the amplifier via a second switch and an enable switch connected in series. The out-of-phase input of the amplifier is grounded via a first switch, and the non-inverting input of the amplifier is grounded. The out-of-phase input of the amplifier is also connected to the first end of the amplifying capacitor, and the second end of the amplifying capacitor is connected to the power supply VDD via a first switch. The output of the amplifier is connected to the second end of the amplifying capacitor via a second switch and then to the first end of the integrating capacitor via a second switch. The second end of the integrating capacitor is connected to the power supply VDD. The out-of-phase input of the integrator is connected to the first end of the integrating capacitor via a first switch. The out-of-phase input of the integrator is also connected to the first end of the charge transfer capacitor. The non-inverting input of the integrator is connected to a reference voltage. The output of the integrator is connected to the second end of the charge transfer capacitor, and the second end of the charge transfer capacitor is also connected to the detection control circuit.

[0020] The detection control circuit selects a specific touch key module that needs to be detected by controlling the enable switch, and controls the first switch T1 and the plurality of second switches T2 to be alternately turned on after the specific touch key module is selected.

[0021] Preferably, the first switch and the second switch are controlled by two-phase non-overlapping clock signals, and the non-overlapping time is 4ns.

[0022] Preferably, in the sampling integration state, the first switch is turned on and the second switch is turned off; in the amplification transfer state, the second switch is turned on and the first switch is turned off.

[0023] Preferably, the detection control circuit includes a control circuit and a voltage detection circuit, the control circuit is used to control the state of the switching circuit, the voltage detection circuit is connected to the second end of the charge transfer capacitor to detect the voltage on the charge transfer capacitor and outputs an interrupt signal to the control circuit when the detected voltage reaches a threshold voltage. When the control circuit receives the interrupt signal, it records the number of integration times at this time, and if the number of integration times is less than a preset number, it is determined that the key is touched.

[0024] Preferably, the switching circuit further includes three third switches and one fourth switch, the states of the third switches and the fourth switches being opposite at any time, the two ends of the first switch located between the out-of-phase input end of the integrator and the first end of the integrating capacitor being connected to the power supply VDD via a third switch respectively, a fourth switch is provided between the output end of the integrator and the second end of the charge transfer capacitor, and the second end of the charge transfer capacitor is also grounded via a third switch.

[0025] Preferably, the detection control circuit controls the capacitive touch sensing module to enter an intermediate state after initialization before controlling the capacitive touch sensing module to alternately switch between the sampling integration state and the amplification transfer state;

[0026] During initialization, the first switch, the second switch, and the fourth switch are all disconnected, and the third switch is turned on. In the intermediate state, the first switch, the second switch, and the third switch are disconnected, and the fourth switch is turned on. In the sampling and integration state, the first switch and the fourth switch are turned on, and the second and third switches are disconnected. In the amplification and transfer state, the second switch and the fourth switch are turned on, and the first switch and the third switch are disconnected.

[0027] On the other hand, the present invention also constructs a capacitive touch sensing method, which is implemented based on the capacitive touch sensing module described in any of the above items. The method includes: the detection control circuit selects the specific touch button module for detection by controlling the state of the switching circuit, and controls the capacitive touch sensing module to alternately switch between the sampling integration state and the amplification transfer state during the process of selecting the specific touch button module for detection, and when the output voltage of the capacitive integration circuit reaches the threshold voltage, records the number of integrations at this time; if the number of integrations is less than the preset number, it is determined that the button is touched.

[0028] The capacitive touch sensing module and method of the present invention have the following beneficial effects: the present invention does not require external capacitors, all components required for the circuit can be internally integrated, and no pins for external capacitors need to be reserved, which does not occupy additional space on the PCB board and does not increase the application cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only embodiments of the present invention. Those skilled in the art can also derive other drawings based on the provided drawings without inventive work.

[0030] Figure 1 This is the circuit structure diagram of the existing touch detection module;

[0031] Figure 2 This is a circuit diagram of the capacitive touch sensing module of the present invention;

[0032] Figure 3 It is the equivalent circuit diagram during initialization;

[0033] Figure 4 It is the equivalent circuit diagram in the sampling integration state;

[0034] Figure 5 It is the equivalent circuit diagram when the transfer state is amplified;

[0035] Figure 6 This is the timing diagram of the capacitive touch sensing module when it is working. DETAILED DESCRIPTION

[0036] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The drawings illustrate exemplary embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0038] It should be noted that the words "connected" or "connected" herein include not only directly connecting two entities, but also indirectly connecting through other entities with beneficial improvement effects. Terms containing ordinal numbers such as "first" and "second" used in this specification can be used to describe various constituent elements, but these constituent elements are not limited by these terms. The purpose of using these terms is only to distinguish one constituent element from other constituent elements. For example, without departing from the scope of the present invention, the first constituent element can be named as the second constituent element, and similarly, the second constituent element can also be named as the first constituent element.

[0039] The general idea of ​​the present invention is to construct a capacitive touch sensing module, including:

[0040] a capacitance amplifying circuit, connected to at least one touch key module, for sensing capacitance introduced when the touch key is touched;

[0041] a capacitance integration circuit connected to the capacitance amplification circuit;

[0042] a switch circuit, comprising a plurality of switches distributed in the touch key module, the capacitance amplifying circuit, and the capacitance integrating circuit, for controlling the states of the touch key module, the capacitance amplifying circuit, and the capacitance integrating circuit by changing the switch states;

[0043] a detection control circuit connected to the switch circuit and the capacitive integration circuit, configured to select a specific touch key module for detection by controlling the state of the switch circuit, and to control the capacitive touch sensing module to alternately switch between a sampling integration state and an amplification transfer state during the detection process, and to record the number of integrations when the output voltage of the capacitive integration circuit reaches a threshold voltage, and to determine that the key is touched if the number of integrations is less than a preset number;

[0044] Among them, when in the sampling integration state, the capacitor amplifier circuit collects the charge signal on the touch button and the capacitor integration circuit generates an integrated accumulated voltage; when in the amplification transfer state, the capacitor amplifier circuit amplifies the collected charge signal and the capacitor integration circuit transfers the charge signal amplified by the capacitor amplifier circuit.

[0045] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the drawings and specific implementation methods of the specification. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present application, rather than limitations on the technical solution of the present application. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0046] Example 1

[0047] refer to Figure 2 This embodiment discloses a capacitive touch sensing module, including a capacitance amplifying circuit 101, a capacitance integrating circuit 102, a switching circuit, and a detection control circuit 103. The detection control circuit 103 further includes a control circuit and a voltage detection circuit.

[0048] The capacitance amplifier circuit 101 is connected to at least one touch key module 100, each of which includes a touch key. The figure shows n touch keys key1-keyn, where n is a positive integer. The capacitance amplifier circuit 101 is used to sense the capacitance introduced when a touch key is touched, collect charge signals on the touch key, and amplify the collected charge signals.

[0049] The capacitance integration circuit 102 is connected to the capacitance amplifier circuit 101 and is used to transfer the charge signal amplified by the capacitance amplifier circuit 101 and generate an integrated voltage.

[0050] The switch circuit includes a plurality of switches distributed in the at least one touch key module 100, the capacitance amplifying circuit 101, and the capacitance integrating circuit 102, and is configured to control the states of the at least one touch key module 100, the capacitance amplifying circuit 101, and the capacitance integrating circuit 102 by changing the switch states;

[0051] Wherein, the voltage detection circuit is used to detect the voltage on the charge transfer capacitor C4 and output an interrupt signal to the control circuit when the detected voltage reaches a threshold voltage;

[0052] The control circuit is used to control the state of the switch circuit, select the specific touch button module for detection, and control the capacitive touch sensing module to alternately switch between the sampling integration state and the amplification transfer state during the detection process. In the sampling integration state, the capacitive amplifier circuit 101 collects the charge signal on the touch button and the capacitive integration circuit 102 generates an integrated and accumulated voltage; in the amplification transfer state, the capacitive amplifier circuit 101 amplifies the collected charge signal and the capacitive integration circuit 102 transfers the charge signal amplified by the capacitive amplifier circuit 101. The control circuit is also used to record the number of integrations at this time when an interrupt signal is received, and if the number of integrations is less than a preset number, it is determined that the button is touched.

[0053] The capacitance amplification circuit 101 includes an amplifier AMP_1 and an amplifying capacitor C2. The capacitance integration circuit 102 includes an integrator AMP_2, an integration capacitor C3, and a charge transfer capacitor C4. The switching circuit includes n enable switches, n+3 first switches T1, and n+2 second switches T2. Each touch key module 100 is distributed with a first switch T1, a second switch, and an enable switch Key_en. The capacitance amplification circuit 101 is distributed with two first switches T1 and two second switches T2, and the capacitance integration circuit 102 is distributed with one first switch T1. During detection, the touch key module 100 to be detected is selected by controlling the enable switch Key_en (if the enable switch Key_en is turned on, it indicates that it is selected for detection; if the enable switch Key_en is turned off, it indicates that no detection is required). After the specific touch key module 100 is selected, the first switch T1 and the plurality of second switches T2 are controlled to be alternately turned on. Preferably, the switch circuit further includes three third switches T3 and one fourth switch T4, and the states of the third switches T3 and the fourth switches T4 are opposite at any time. Figure 6 In FIG, pre is the control signal of T3, and the control signal of T4 is opposite to pre. It is understood that the switch in the present invention includes various equivalent switching electronic devices, not limited to diodes or transistors.

[0054] Specifically, Figure 2Where C1 is the sum of the PAD parasitic capacitance and stray capacitance, and Ctouch is the capacitance introduced by the finger during touch. The capacitance C1 is approximately 10pF, the amplification capacitance C2 is 50pF, the integration capacitance C3 is 200fF, and the charge transfer capacitance C4 is 40pF. The positive electrode of each touch button is connected to the power supply VDD via a corresponding first switch T1. Each touch button's positive electrode is also connected to the out-of-phase input of the amplifier AMP_1 via a second switch and an enable switch connected in series. In other words, all touch button modules 100 are connected to the touch_bus line via the enable switch key_en and fed into the input of AMP_1. The out-of-phase input terminal of the amplifier AMP_1 is grounded via a first switch T1, and the in-phase input terminal of the amplifier AMP_1 is grounded. The out-of-phase input terminal of the amplifier AMP_1 is also connected to the first terminal of the amplifying capacitor C2. The second terminal of the amplifying capacitor C2 is connected to the power supply VDD via a first switch T1. The output terminal of the amplifier AMP_1 is connected to the second terminal of the amplifying capacitor C2 via a second switch T2 and to the first terminal of the integrating capacitor C3 via a second switch T2. The second terminal of the integrating capacitor C3 is connected to the power supply VDD. The out-of-phase input terminal of the integrator AMP_2 is connected to the first terminal of the amplifying capacitor C2 via a first switch T1. The first end of the integrating capacitor C3 is connected, the out-of-phase input end of the integrator AMP_2 is also connected to the first end of the charge transfer capacitor C4, the non-inverting input end of the integrator AMP_2 is connected to the reference voltage, the output end of the integrator AMP_2 is connected to the second end of the charge transfer capacitor C4 via a fourth switch T4, the second end of the charge transfer capacitor C4 is also grounded via a third switch T3, the second end of the charge transfer capacitor C4 is also connected to the voltage detection circuit, and the two ends of the first switch T1 located between the out-of-phase input end of the integrator AMP_2 and the first end of the integrating capacitor C3 are respectively connected to the power supply VDD via a third switch T3.

[0055] refer to Figure 6Specifically, before controlling the capacitive touch sensing module to enter the sampling and integration state, the detection control circuit 103 controls the capacitive touch sensing module to enter the intermediate state after initialization. During initialization, the first switch T1, the second switch T2, and the fourth switch T4 are all disconnected, and the third switch T3 is turned on; in the intermediate state, the first switch T1, the second switch T2, and the third switch T3 are disconnected, and the fourth switch T4 is turned on; in the sampling and integration state, the first switch T1 and the fourth switch T4 are turned on, and the second switch T2 and the third switch T3 are disconnected; in the amplification and transfer state, the second switch T2 and the fourth switch T4 are turned on, and the first switch T1 and the third switch T3 are disconnected. In this embodiment, the first switch T1 and the second switch T2 are controlled by two-phase non-overlapping clock signals, and the non-overlapping time is 4ns, that is, the interval between the sampling and integration state and the amplification and transfer state is 4ns.

[0056] The following combination Figure 3-6 , the working principle of this embodiment is described in detail:

[0057] The amplifier AMP_1 will collect the charge signal on the touch button PAD and then amplify it. The amplified signal will be collected by the integrator AMP_2, and finally generate an integrated accumulated voltage for detection by the voltage detection circuit. Each integration count is performed once. Figure 6 Touch_En represents the enable signal for detection. Upon receiving this signal, the control circuit controls the entire module, initializing it to an intermediate state and then starting counting (CLK_EN is the counter's enable signal; a high signal indicates counting has begun). The circuit alternates between sampling and integration and amplification and transfer states. During these two states, when the voltage detection circuit detects that the output voltage vout of integrator AMP_2 reaches the set threshold voltage, it records the number of integrations at that time. When a finger presses the PAD, the detection capacitance increases, resulting in a decrease in the number of integrations at the same threshold voltage, signaling a touch event. To enhance the circuit's anti-interference capabilities, VREF_BUF is internally used to provide a regulated voltage reference.

[0058] Specifically, refer to Figure 3 Initialization is required at the beginning of each detection process, mainly to initialize C3 and C4, so that C3 is not charged at the beginning and C4 is charged with VDD*GND. The default output VOUT of integrator AMP_2 is GND.

[0059] Capacitor C3 charge:

[0060] Q3=0……(1)

[0061] Capacitor C4 charge:

[0062] Q4=VDD*GND……(2)

[0063] refer to Figure 4 Next, the sampling and integration state begins. Amplifier AMP_1 is in the sampling state, and the integrator is in the integrating state. At this point, VDD charges C1 and C2 for amplifier AMP_1, while the charge in integrator AMP_2 is transferred from C3 to C4. Due to initialization, no charge is transferred in the first step, so the charge on C4 remains unchanged. Charge will be transferred to C4 in subsequent steps.

[0064] Capacitor Q1 charge:

[0065] Q1=VDD*C1……(3)

[0066] Capacitor Q2 charge:

[0067] Q2=VDD*C2……(4)

[0068] Due to the conservation of charge:

[0069] Q3+Q4'=(VDD-VDD)*C3+(VOUT-VDD)*C4……(5)

[0070] (VDD-Vsample)*C3=(VOUT-VOUT')*C4……(6)

[0071] In the above formula, Q4' is the charge stored in capacitor C4 at the previous moment, and Vsample is the sampled voltage of C3 at the previous moment, so the output voltage of integrator AMP_2 is:

[0072] VOUT=VOUT'+(VDD-Vsample) / 200......(7)

[0073] VOUT' is the integrator output voltage at the previous moment.

[0074] Then the amplified transfer state is Figure 5 As shown, amplifier AMP_1 amplifies the sampled charge signal and transfers it to capacitor C3. The output of integrator AMP_2 remains unchanged at this time due to charge conservation:

[0075] Q1'+Q2'=Vsample*Q2……(8)

[0076] You can get:

[0077] Vsample=4 / 5*VDD……(9)

[0078] Combining equations (7) and (9), we can get the final output of integrator AMP_2 through the expression:

[0079] VOUT=VOUT'+VDD / 1000……(10)

[0080] That is to say, the integrated output voltage is 1 / 1000 of VDD each time it is integrated.

[0081] Changing the ratios of C1, C2, C3, and C4 can adjust the step size of the final integrator AMP_2 output. Changing the threshold voltage of the voltage detection circuit can change the size of the final detected count value.

[0082] It's understandable that this circuit can detect a single touch key or multiple touch keys simultaneously. Specifically, the enable switch Key_en is used to select the touch key to be detected. Generally, a scanning method is used to detect each touch key one by one. Furthermore, when detecting multiple touch keys simultaneously, the detection threshold needs to be reset.

[0083] Example 2

[0084] Based on the same inventive concept, the present invention discloses a capacitive touch sensing method, which is implemented based on the capacitive touch sensing module described in Example 1. The method includes: the detection control circuit 103 selects the specific touch button module 100 for detection by controlling the state of the switch circuit, and controls the capacitive touch sensing module to alternately switch between a sampling integration state and an amplification transfer state during the process of selecting the specific touch button module 100 for detection, and when the output voltage of the capacitive integration circuit 102 reaches a threshold voltage, records the number of integration times at this time, and determines that the button is touched if the number of integration times is less than a preset number.

[0085] Specifically, the control circuit first controls the capacitive touch sensing module to enter an intermediate state after initialization, and then alternately switches between a sampling and integration state and an amplification and transfer state. Specifically, during initialization, the first switch T1, the second switch T2, and the fourth switch T4 are all disconnected, and the third switch T3 is turned on. In the intermediate state, the first switch T1, the second switch T2, and the third switch T3 are disconnected, and the fourth switch T4 is turned on. In the sampling and integration state, the first switch T1 and the fourth switch T4 are turned on, and the second switch T2 and the third switch T3 are disconnected. In the amplification and transfer state, the second switch T2 and the fourth switch T4 are turned on, and the first switch T1 and the third switch T3 are disconnected. In this embodiment, the first switch T1 and the second switch T2 are controlled by two-phase non-overlapping clock signals with a non-overlap time of 4ns.

[0086] In summary, the capacitive touch sensing module and method of the present invention have the following advantages: the present invention does not require external capacitors, all components required for the circuit can be internally integrated, and there is no need to reserve pins for external capacitors, which does not occupy additional space on the PCB board and does not increase the cost of the application.

[0087] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A capacitive touch sensing module, characterized in that: include: a capacitance amplifying circuit, connected to at least one touch key module, for sensing capacitance introduced when the touch key is touched; a capacitance integration circuit connected to the capacitance amplification circuit; a switch circuit, comprising a plurality of switches distributed in the at least one touch key module, the capacitance amplifying circuit, and the capacitance integrating circuit, for controlling the states of the at least one touch key module, the capacitance amplifying circuit, and the capacitance integrating circuit by changing switch states; a detection control circuit connected to the switch circuit and the capacitive integration circuit, configured to select a specific touch key module for detection by controlling the state of the switch circuit, and to control the capacitive touch sensing module to alternately switch between a sampling integration state and an amplification transfer state during the process of selecting the specific touch key module for detection, and to record the number of integrations when the output voltage of the capacitive integration circuit reaches a threshold voltage, and determine that the key is touched if the number of integrations is less than a preset number; Wherein, in the sampling integration state, the capacitor amplifier circuit collects the charge signal on the touch key and the capacitor integration circuit generates an integrated and accumulated voltage; in the amplification transfer state, the capacitor amplifier circuit amplifies the collected charge signal and the capacitor integration circuit transfers the charge signal amplified by the capacitor amplifier circuit; Each of the touch key modules includes a touch key, the capacitance amplification circuit includes an amplifier and an amplifying capacitor, the capacitance integration circuit includes an integrator, an integrating capacitor, and a charge transfer capacitor, and the switch circuit includes a first switch, a second switch, and an enabling switch, wherein: each of the touch key modules is distributed with a first switch, a second switch, and an enabling switch, the capacitance amplification circuit is distributed with two first switches and two second switches, and the capacitance integration circuit is distributed with one first switch; The positive electrode of each touch key is connected to the power supply VDD via a first switch, and the positive electrode of each touch key is also connected to the out-of-phase input of the amplifier via a second switch and an enable switch connected in series. The out-of-phase input of the amplifier is grounded via a first switch, and the non-inverting input of the amplifier is grounded. The out-of-phase input of the amplifier is also connected to the first end of the amplifying capacitor, and the second end of the amplifying capacitor is connected to the power supply VDD via a first switch. The output of the amplifier is connected to the second end of the amplifying capacitor via a second switch and then to the first end of the integrating capacitor via a second switch. The second end of the integrating capacitor is connected to the power supply VDD. The out-of-phase input of the integrator is connected to the first end of the integrating capacitor via a first switch. The out-of-phase input of the integrator is also connected to the first end of the charge transfer capacitor. The non-inverting input of the integrator is connected to a reference voltage. The output of the integrator is connected to the second end of the charge transfer capacitor, and the second end of the charge transfer capacitor is also connected to the detection control circuit. The detection control circuit selects a specific touch key module that needs to be detected by controlling the enable switch, and controls the plurality of first switches T1 and the plurality of second switches T2 to be alternately turned on after the specific touch key module is selected.

2. The capacitive touch sensing module according to claim 1, wherein: The first switch and the second switch are controlled by two-phase non-overlapping clock signals, and the non-overlapping time is 4ns.

3. The capacitive touch sensing module according to claim 2, wherein: In the sampling integration state, the first switch is turned on and the second switch is turned off; in the amplification transfer state, the second switch is turned on and the first switch is turned off.

4. The capacitive touch sensing module according to claim 2, wherein: The detection control circuit includes a control circuit and a voltage detection circuit. The control circuit is used to control the state of the switching circuit. The voltage detection circuit is connected to the second end of the charge transfer capacitor to detect the voltage on the charge transfer capacitor and outputs an interrupt signal to the control circuit when the detected voltage reaches a threshold voltage. When the control circuit receives the interrupt signal, it records the number of integration times at this time. If the number of integration times is less than a preset number, it is determined that the key is touched.

5. The capacitive touch sensing module according to claim 2, wherein: The switching circuit also includes three third switches and one fourth switch. The states of the third switches and the fourth switches are opposite at any time. The two ends of the first switch located between the out-of-phase input end of the integrator and the first end of the integrating capacitor are respectively connected to the power supply VDD via a third switch. A fourth switch is set between the output end of the integrator and the second end of the charge transfer capacitor. The second end of the charge transfer capacitor is also grounded via a third switch.

6. The capacitive touch sensing module according to claim 5, characterized in that: The detection control circuit controls the capacitive touch sensing module to enter an intermediate state after initialization before controlling the capacitive touch sensing module to alternately switch between the sampling integration state and the amplification transfer state; During initialization, the first switch, the second switch, and the fourth switch are all disconnected, and the third switch is turned on; in the intermediate state, the first switch, the second switch, and the third switch are disconnected, and the fourth switch is turned on; in the sampling and integration state, the first switch and the fourth switch are turned on, and the second switch and the third switch are disconnected; In the amplification transition state, the second switch and the fourth switch are turned on, and the first switch and the third switch are turned off.

7. A capacitive touch sensing method, characterized in that: Based on the capacitive touch sensing module according to any one of claims 1 to 6, the method includes: the detection control circuit selects the specific touch key module for detection by controlling the state of the switch circuit, and controls the capacitive touch sensing module to alternately switch between a sampling integration state and an amplification transfer state during the process of selecting the specific touch key module for detection, and when the output voltage of the capacitive integration circuit reaches a threshold voltage, records the number of integration times at this time, and determines that the key is touched if the number of integration times is less than a preset number.

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