A current output circuit

Abstract

The present application discloses a current output circuit, including a control chip, the control chip is provided with a first control terminal for outputting a first PWM signal; at least one output circuit, including a conversion unit for converting direct current into alternating current, a resonance matching unit for resonating the alternating current, and an output electrode for contacting the skin, the input terminal of the conversion unit is connected to the first control terminal, the output terminal of the conversion unit is connected to the resonance matching unit, and the resonance matching unit is also connected to the output electrode; a direct current power supply, the direct current power supply supplies power to the control chip and the output circuit; an input electrode for contacting the skin, the input electrode is connected to the negative pole of the direct current power supply. The present application utilizes the capacitance of the skin between the resonance matching unit and the output electrode and the input electrode to form a resonant circuit, so that the alternating current can oscillate at a specific frequency, can make full use of the capacitance characteristics of human skin, improve the efficiency of energy conversion, and reduce energy loss.

Description

Technical Field

[0001] The present application relates to the field of beauty technology, and in particular to a current output circuit. Background Art

[0002] The basic circuit of traditional radio frequency beauty devices is to convert direct current into radio frequency alternating current through a push-pull conversion circuit model, and then increase the power through a transformer. This circuit form does not fully utilize the inherent capacitance characteristics of human skin. Due to the influence of capacitance in human skin, the current conversion efficiency is low, the heat conversion efficiency is low, and a huge transformer is required, which is not conducive to product miniaturization. Utility Model Content

[0003] The purpose of the present application is to overcome the deficiency in the prior art that the current output circuit does not take into account the low conversion efficiency caused by human skin, and to provide a current output circuit that can fully utilize the capacitance characteristics of the human body and improve the energy conversion efficiency.

[0004] The technical solution of the present application provides a current output circuit, comprising

[0005] A control chip, wherein the control chip is provided with a first control terminal for outputting a first PWM signal;

[0006] at least one output circuit, comprising a conversion unit for converting direct current into alternating current, a resonance matching unit for resonating the alternating current, and an output electrode for contacting the skin, wherein an input end of the conversion unit is connected to the first control end, an output end of the conversion unit is connected to the resonance matching unit, and the resonance matching unit is also connected to the output electrode;

[0007] A direct current power supply, the direct current power supply supplies power to the control chip and the output circuit;

[0008] An input electrode for contacting the skin, wherein the input electrode is connected to the negative pole of the DC power supply.

[0009] Further, the resonant matching unit includes a resonant inductor, a resonant capacitor and a first capacitor;

[0010] One end of the resonant inductor is connected to the conversion unit, and the other end is connected to the output electrode through the resonant capacitor. One end of the first capacitor is connected to the conversion unit, and the other end is connected to the negative electrode of the DC power supply.

[0011] Further, the conversion unit includes a MOS tube, a first resistor, a second resistor, a third resistor and a first inductor;

[0012] The gate of the MOS tube is connected to the first control end through the first resistor, the source of the MOS tube is connected to the negative electrode of the DC power supply through the second resistor, one end of the third resistor is connected to the gate of the MOS tube, and the other end is connected to the negative electrode of the DC power supply, one end of the first inductor is connected to the drain of the MOS tube, and the other end is connected to the positive electrode of the DC power supply, and the drain of the MOS tube is also connected to the resonant matching unit.

[0013] Further, the resonant inductor comprises at least two parallel inductor branches, each of which comprises a first switch element and a resonant inductor element connected in series, and the inductance value of the resonant inductor element in each of the inductor branches is different;

[0014] The resonant capacitor comprises at least two parallel capacitor branches, each capacitor branch comprises a second switch element and a resonant capacitor element connected in series, and the capacitance value of the resonant capacitor element in each capacitor branch is different.

[0015] Furthermore, it also includes a capacitance detection circuit for detecting the skin, and the control chip is provided with a second control terminal for outputting a second PWM signal and a receiving terminal for receiving a capacitance signal;

[0016] The capacitance detection circuit is connected to the receiving end, the second control end, the input electrode and the output electrode, and the DC power supply supplies power to the capacitance detection circuit.

[0017] Furthermore, the capacitance detection circuit includes

[0018] a first operational amplifier unit for converting the second PWM signal into a sine wave signal, wherein the first operational amplifier unit is connected to the second control terminal;

[0019] a second operational amplifier unit for amplifying and outputting the sine wave signal, wherein the second operational amplifier unit is connected to the first operational amplifier unit and the input electrode;

[0020] A detection capacitor, one end of which is connected to the output electrode, and the other end of which is connected to the negative electrode of the DC power supply;

[0021] A third operational amplifier circuit is used to amplify the voltage signal between the detection capacitor and the output electrode and input it into the control chip, wherein the input end of the third operational amplifier circuit is connected between the detection capacitor and the output electrode, and the output end of the third operational amplifier circuit is connected to the receiving end.

[0022] Further, the first operational amplifier unit includes a first amplifier, a fourth resistor, a fifth resistor, a sixth resistor and a seventh resistor;

[0023] The non-inverting input terminal of the first amplifier is connected to the second control terminal;

[0024] The inverting input terminal of the first amplifier is connected to the positive power supply terminal of the DC power supply through the fourth resistor and the fifth resistor, one end of the sixth resistor is connected between the fourth resistor and the fifth resistor, and the other end is connected to the negative power supply terminal of the DC power supply;

[0025] The output end of the first amplifier is connected to the second operational amplifier unit, and the seventh resistor is further connected between the output end and the inverting input end.

[0026] Furthermore, a filtering unit is connected between the in-phase input terminal of the first amplifier and the second control terminal.

[0027] Further, the second operational amplifier unit includes a second amplifier and an eighth resistor;

[0028] The non-inverting input terminal of the second amplifier is connected to the first operational amplifier unit through the eighth resistor;

[0029] An inverting input terminal of the second amplifier is connected to the output terminal of the second amplifier and to the input electrode.

[0030] Further, the third operational amplifier unit includes a third amplifier, a ninth resistor and a tenth resistor;

[0031] The non-inverting input terminal of the third amplifier is connected between the detection capacitor and the output electrode through the ninth resistor;

[0032] The inverting input terminal of the third amplifier is connected to the output terminal of the third amplifier and is connected to the receiving terminal through the tenth resistor.

[0033] After adopting the above technical solution, the following beneficial effects are achieved:

[0034] In the output circuit of the present application, the conversion unit converts direct current into alternating current using the first PWM signal output by the control chip, and then uses the resonance matching unit and the capacitance of the skin between the output electrode and the input electrode to form a resonant circuit, so that the alternating current can oscillate at a specific frequency, which can make full use of the capacitance characteristics of human skin, improve the efficiency of energy conversion, and reduce energy loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The disclosure of the present application will become easier to understand with reference to the accompanying drawings. It should be understood that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present application. In the drawings:

[0036] Figure 1It is one of the circuit structure schematic diagrams in the first embodiment of the present application;

[0037] Figure 2 This is the second circuit structure diagram in the first embodiment of the present application;

[0038] Figure 3 It is one of the circuit structure diagrams in the second embodiment of the present application;

[0039] Figure 4 This is the second circuit structure diagram in the second embodiment of the present application;

[0040] Figure 5 This is the third circuit structure schematic diagram in the second embodiment of the present application.

[0041] Reference table of reference numerals:

[0042] Control chip 01 , output circuit 02 , conversion unit 21 , resonance matching unit 22 , output electrode 23 , input electrode 03 , capacitance detection circuit 04 . DETAILED DESCRIPTION

[0043] The specific implementation of the present application is further described below with reference to the accompanying drawings.

[0044] It is easy to understand that according to the technical solution of the present application, without changing the essential spirit of the present application, a variety of structural modes and implementation modes that can be replaced by those skilled in the art can be replaced with each other. Therefore, the following specific implementation modes and drawings are only exemplary descriptions of the technical solution of the present application, and should not be regarded as the entirety of the present application or as a limitation or restriction on the technical solution of the application.

[0045] The directional terms such as up, down, left, right, front, back, front, back, top, bottom, etc. mentioned or may be mentioned in this specification are defined relative to the structures shown in the drawings. They are relative concepts and may change accordingly according to their different positions and different usage conditions. Therefore, these or other directional terms should not be interpreted as restrictive terms. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0046] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above-mentioned in this application can be understood according to the specific circumstances.

[0047] Embodiment 1:

[0048] The current output circuit in the embodiment of the present application includes:

[0049] A control chip 01, wherein the control chip is provided with a first control terminal PWM RF for outputting a first PWM signal;

[0050] At least one output circuit 02, including a conversion unit 21 for converting direct current into alternating current, a resonance matching unit 22 for resonating the alternating current, and an output electrode 23 for contacting the skin, wherein the input end of the conversion unit 21 is connected to the first control end PWM RF, the output end of the conversion unit 21 is connected to the resonance matching unit 22, and the resonance matching unit 22 is also connected to the output electrode 23;

[0051] A DC power supply, which supplies power to the control chip 01 and the output circuit 02;

[0052] The input electrode 03 is used for contacting with the skin, and the input electrode 03 is connected to the negative pole of the DC power supply.

[0053] The control chip 01 may be a controller with program execution and data processing capabilities, such as a single-chip microcomputer, an embedded chip, a programmable logic controller, etc. In this embodiment, the control chip 01 is a single-chip microcomputer. Figure 2 The circuit structure of the single-chip microcomputer and its minimum system is shown, and a DC power supply is used to power the single-chip microcomputer.

[0054] The control chip 01 is provided with a first control terminal PWM RF, which is used to output a first PWM signal to the conversion unit 21 of the output circuit 02. The conversion unit 21 generates alternating current under the control of the first PWM signal. Specifically, the first PWM signal can be used to control the on and off of the switch tube so that the switch tube outputs alternating current. The conversion unit 21 inputs the alternating current into the resonant matching unit 22. The resonant matching unit 22 and the skin capacitance Cp between the output electrode 23 and the input electrode 03 form a resonant circuit, so that the alternating current can oscillate at a specific frequency, thereby outputting a stable alternating current.

[0055] The current output circuit of the embodiment of the present application takes into account the capacitance of human skin, and sets a resonant matching unit and the capacitance of human skin to form a resonant circuit, which can fully utilize the capacitance characteristics of human skin, improve the efficiency of energy conversion, and reduce energy loss.

[0056] Furthermore, if Figure 1 As shown, the resonant matching unit 22 includes a resonant inductor L1, a resonant capacitor C1 and a first capacitor C2;

[0057] One end of the resonant inductor L1 is connected to the conversion unit 21, and the other end is connected to the output electrode 23 through the resonant capacitor C1. One end of the first capacitor C2 is connected to the conversion unit 21, and the other end is connected to the negative electrode of the DC power supply.

[0058] Specifically, the resonant inductor L1, the resonant capacitor C1, the first capacitor C2 and the skin capacitor Cp between the output electrode 23 and the input electrode 03 form a resonant circuit. By adjusting the inductance value of the resonant inductor L1 and the capacitance value of the resonant capacitor C1, the oscillation frequency of the alternating current can be changed. The first capacitor C2 is a parallel capacitor, which is used to maintain the voltage at the moment when the switch tube in the conversion unit 21 is turned from closed to open.

[0059] Furthermore, if Figure 1 As shown, the conversion unit 21 includes a MOS tube Q1, a first resistor R1, a second resistor R2, a third resistor R3 and a first inductor L2;

[0060] The gate of the MOS tube Q1 is connected to the first control end PWM RF through the first resistor R1, the source of the MOS tube Q1 is connected to the negative electrode of the DC power supply through the second resistor R2, one end of the third resistor R3 is connected to the gate of the MOS tube Q1, and the other end is connected to the negative electrode of the DC power supply, one end of the first inductor L2 is connected to the drain of the MOS tube Q1, and the other end is connected to the positive electrode of the DC power supply, and the drain of the MOS tube Q1 is also connected to the resonant matching unit 22.

[0061] Specifically, when the first control terminal PWM RF inputs a high level to the gate of the MOS transistor Q1, the drain and source of the MOS transistor Q1 are turned on, and when the first control terminal PWM RF inputs a low level to the gate of the MOS transistor Q1, the drain and source of the MOS transistor Q1 are turned off, thereby converting the PWM signal output by the first control terminal PWM RF into an AC output. The first inductor L2 is a choke inductor, which is used to reduce the high-frequency current signal in the power supply from entering the circuit, and only allows low-frequency and DC current signals to enter the circuit, so as to reduce the interference signal in the AC signal output by the conversion unit 21.

[0062] The current output circuit in the embodiment of the present application can be used to output radio frequency current in a radio frequency beauty instrument, which can make full use of the capacitive characteristics of human skin, improve the efficiency of energy conversion, and reduce energy loss.

[0063] Embodiment 2:

[0064] The current output circuit in the embodiment of the present application is as follows: Figure 3-5As shown, similar to the current output circuit of the first embodiment, it includes a control chip 01, an output circuit 02 and an input electrode 03. The output circuit 02 includes a conversion unit 21, a resonant matching unit 22 and an output electrode 23. In the embodiment of the present application, except that the resonant inductor and the resonant capacitor in the resonant matching unit 22 are different from those in the first embodiment, and a capacitance detection circuit 04 is added, the rest of the circuit structure is the same as that in the first embodiment. Only the above differences are described below, and other circuit structures can refer to the first embodiment.

[0065] In the present application embodiment, Figure 3 As shown, the resonant inductor in the resonant matching unit 22 includes at least two parallel inductor branches, each of which includes a first switch element and a resonant inductor element connected in series, and the inductance value of the resonant inductor element in each inductor branch is different;

[0066] The resonant capacitor comprises at least two parallel capacitor branches, each capacitor branch comprises a second switch element and a resonant capacitor element connected in series, and the capacitance value of the resonant capacitor element in each capacitor branch is different.

[0067] by Figure 3 Taking the output circuit 02 shown as an example, the resonant inductor includes three parallel inductance branches, wherein the first switch K1 and the resonant inductor L11 form a first inductance branch, the first switch K3 and the resonant inductor L12 form a second inductance branch, and the first switch K5 and the resonant inductor L13 form a third inductance branch. The resonant capacitor includes three parallel capacitance branches, wherein the second switch K2 and the resonant capacitor C11 form a first capacitance branch, the second switch K4 and the resonant capacitor C12 form a second capacitance branch, and the second switch K6 and the resonant capacitor C13 form a third capacitance branch. Each inductance branch is connected in series with each capacitance branch.

[0068] The resonant inductor and the resonant capacitor in the embodiment of the present application can be adjusted, and one of the inductor branches and one of the capacitor branches can be selected to be turned on as needed, so that a suitable resonant inductor and resonant capacitor can be selected for different skin types.

[0069] Furthermore, if Figure 4 , 5 As shown, the current output circuit also includes a capacitance detection circuit 04 for detecting the skin, and the control chip 01 is provided with a second control terminal PWM_C for outputting a second PWM signal and a receiving terminal ADC for receiving a capacitance signal;

[0070] The capacitance detection circuit 04 is connected to the receiving end ADC, the second control end PWM_C, the input electrode 23 and the output electrode 03 , and the DC power supply supplies power to the capacitance detection circuit 04 .

[0071] In the embodiment of the present application, the control chip 01 outputs two PWM signals through the second control terminal PWM_C to control the capacitance detection circuit 04, and receives the detection signal of the capacitance detection circuit 04 through the receiving terminal ADC to obtain the capacitance value of the skin.

[0072] Specifically, the capacitance detection circuit 04 includes

[0073] A first operational amplifier unit for converting the second PWM signal into a sine wave signal, the first operational amplifier unit being connected to the second control terminal PWM_C;

[0074] A second operational amplifier unit for amplifying and outputting the sine wave signal, the second operational amplifier unit being connected to the first operational amplifier unit and the input electrode 23;

[0075] A detection capacitor C3, one end of the detection capacitor C3 is connected to the output electrode 03, and the other end is connected to the negative electrode of the DC power supply;

[0076] The third operational amplifier circuit is used to amplify the voltage signal between the detection capacitor C3 and the output electrode 03 and input it into the control chip 01. The input end of the third operational amplifier circuit is connected between the detection capacitor C3 and the output electrode 03, and the output end of the third operational amplifier circuit is connected to the receiving end ADC.

[0077] The capacitance detection circuit 04 converts the second PWM signal output by the second control terminal PWM_C into a sinusoidal wave signal through the first operational amplifier unit, and then amplifies the sinusoidal wave signal through the second operational amplifier unit and inputs it into the human skin through the input electrode 23. The detection capacitor C3 is connected between the output electrode 03 and the negative pole of the DC power supply. The amplified sinusoidal wave signal is input into the human skin, which will charge the skin capacitance and the detection capacitor C3. The voltage signal at the end of the detection capacitor C3 in contact with the output human skin is amplified by the third operational amplifier circuit and then input into the control chip 01 from the receiving end ADC. The control chip calculates the skin capacitance value by algorithms such as FTT based on the voltage signal obtained by the receiving end ADC.

[0078] In the embodiment of the present application, the control chip 01 can obtain the skin capacitance value through the capacitance detection circuit 04, and determine the resonant capacitor and the resonant inductor according to the skin capacitance value based on preset rules, control the corresponding inductor branch and capacitor branch to be turned on, and can select the resonant capacitor and inductor according to the skin capacitance value, so that the entire circuit can work in the best state when contacting different skin parts, thereby improving the conversion efficiency of the circuit and the efficacy of radio frequency beauty.

[0079] like Figure 4 As shown, the first operational amplifier unit includes a first amplifier, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6 and a seventh resistor R7;

[0080] The non-inverting input terminal of the first amplifier is connected to the second control terminal PWM_C;

[0081] The inverting input terminal of the first amplifier is connected to the positive power supply terminal of the DC power supply through the fourth resistor R4 and the fifth resistor R5, one end of the sixth resistor R6 is connected between the fourth resistor R4 and the fifth resistor R5, and the other end is connected to the negative power supply terminal of the DC power supply;

[0082] The output end of the first amplifier is connected to the second operational amplifier unit, and a seventh resistor R7 is further connected between the output end and the inverting input end.

[0083] The circuit formed by the first amplifier, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6 and the seventh resistor R7 converts the square wave into a sine wave signal by using the feedback mechanism of the operational amplifier.

[0084] Furthermore, a filter unit is connected between the in-phase input terminal of the first amplifier and the second control terminal PWM_C. The filter unit is used to filter out interference signals. The filter unit is composed of multiple resistors and capacitors. The filter circuit in the prior art can be used. For the specific circuit structure of the filter circuit in this embodiment, see Figure 4 shown.

[0085] like Figure 4 As shown, the second operational amplifier unit includes a second amplifier and an eighth resistor R8;

[0086] The non-inverting input terminal of the second amplifier is connected to the first operational amplifier unit through the eighth resistor R8;

[0087] The inverting input terminal of the second amplifier is connected to the output terminal of the second amplifier and to the input electrode 23 .

[0088] The second amplifier and the eighth resistor R8 form an amplifier circuit, which amplifies the sine wave signal converted and generated by the first operational amplifier unit and inputs it into the skin through the input electrode 23.

[0089] Among them, the first amplifier and the second amplifier can be integrated in the operational amplifier chip U1, the 8th pin of the operational amplifier chip U1 is connected to the positive power pole of the DC power supply, and the 4th pin is connected to the negative power pole of the DC power supply, which is used to power the first amplifier and the second amplifier; the 1st pin is the output end of the first amplifier, the 2nd pin is the inverting input end of the first amplifier, the 3rd pin is the non-inverting input end of the first amplifier, the 4th pin is the non-inverting input end of the second amplifier, the 5th pin is the inverting input end of the second amplifier, and the 6th pin is the output end of the second amplifier.

[0090] like Figure 4 As shown, the third operational amplifier unit includes a third amplifier, a ninth resistor R9 and a tenth resistor R10;

[0091] The non-inverting input terminal of the third amplifier is connected between the detection capacitor C3 and the output electrode O3 through the ninth resistor R9;

[0092] The inverting input terminal of the third amplifier is connected to the output terminal of the third amplifier and is connected to the receiving end ADC through the tenth resistor R10.

[0093] The third amplifier, the ninth resistor R9 and the tenth resistor R10 form a signal amplifying circuit, which amplifies the voltage signal at one end of the detection capacitor C3 in contact with the output human skin through the third operational amplifier circuit and then inputs it into the control chip 01 from the receiving end ADC.

[0094] The third amplifier may be one of the amplifiers in the operational amplifier chip U2 integrated with two amplifiers, the 8th pin of the operational amplifier chip U2 is connected to the positive pole of the DC power supply, the 4th pin is connected to the negative pole of the DC power supply, and is used as the third amplifier, the 1st pin is the output end of the third amplifier, the 2nd pin is the inverting input end of the third amplifier, and the 3rd pin is the non-inverting input end of the third amplifier. The 5th pin to the 7th pin are the pins of another amplifier, which is not connected to the circuit, so the 5th pin to the 7th pin are all connected to the negative pole of the DC power supply.

[0095] In the embodiment of the present application, the skin capacitance between the input electrode 23 and the output electrode 03 is detected by the capacitance detection circuit 04, and the control chip 01 selects to turn on one inductor branch and one capacitor branch according to the skin capacitance. It can select appropriate resonant capacitors and resonant inductors according to different skin conditions, so that the circuit can maintain its optimal working state and improve the energy conversion efficiency.

[0096] As needed, the above technical solutions can be combined to achieve the best technical effect.

[0097] The above description is only the principle and preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this field, the implementation methods obtained by appropriately combining the technical solutions disclosed in different embodiments are also included in the technical scope of the present invention. On the basis of the principle of the present application, several other variations can be made, which should also be regarded as the protection scope of the present application.

Claims

1. A current output circuit, characterized in that: include A control chip, wherein the control chip is provided with a first control terminal for outputting a first PWM signal; at least one output circuit, comprising a conversion unit for converting direct current into alternating current, a resonance matching unit for resonating the alternating current, and an output electrode for contacting the skin, wherein an input end of the conversion unit is connected to the first control end, an output end of the conversion unit is connected to the resonance matching unit, and the resonance matching unit is also connected to the output electrode; A direct current power supply, the direct current power supply supplies power to the control chip and the output circuit; An input electrode for contacting the skin, wherein the input electrode is connected to the negative pole of the DC power supply.

2. The current output circuit according to claim 1, characterized in that: The resonant matching unit includes a resonant inductor, a resonant capacitor and a first capacitor; One end of the resonant inductor is connected to the conversion unit, and the other end is connected to the output electrode through the resonant capacitor. One end of the first capacitor is connected to the conversion unit, and the other end is connected to the negative electrode of the DC power supply.

3. The current output circuit according to claim 1, characterized in that: The conversion unit includes a MOS tube, a first resistor, a second resistor, a third resistor and a first inductor; The gate of the MOS tube is connected to the first control end through the first resistor, the source of the MOS tube is connected to the negative electrode of the DC power supply through the second resistor, one end of the third resistor is connected to the gate of the MOS tube, and the other end is connected to the negative electrode of the DC power supply, one end of the first inductor is connected to the drain of the MOS tube, and the other end is connected to the positive electrode of the DC power supply, and the drain of the MOS tube is also connected to the resonant matching unit.

4. The current output circuit according to claim 2, characterized in that: The resonant inductor comprises at least two parallel inductor branches, each of which comprises a first switch element and a resonant inductor element connected in series, and the inductance value of the resonant inductor element in each of the inductor branches is different; The resonant capacitor comprises at least two parallel capacitor branches, each capacitor branch comprises a second switch element and a resonant capacitor element connected in series, and the capacitance value of the resonant capacitor element in each capacitor branch is different.

5. The current output circuit according to claim 4, characterized in that: It also includes a capacitance detection circuit for detecting the skin, and the control chip is provided with a second control terminal for outputting a second PWM signal and a receiving terminal for receiving a capacitance signal; The capacitance detection circuit is connected to the receiving end, the second control end, the input electrode and the output electrode, and the DC power supply supplies power to the capacitance detection circuit.

6. The current output circuit according to claim 5, characterized in that: The capacitance detection circuit includes a first operational amplifier unit for converting the second PWM signal into a sine wave signal, wherein the first operational amplifier unit is connected to the second control terminal; a second operational amplifier unit for amplifying and outputting the sine wave signal, wherein the second operational amplifier unit is connected to the first operational amplifier unit and the input electrode; A detection capacitor, one end of which is connected to the output electrode, and the other end of which is connected to the negative electrode of the DC power supply; A third operational amplifier circuit is used to amplify the voltage signal between the detection capacitor and the output electrode and input it into the control chip, wherein the input end of the third operational amplifier circuit is connected between the detection capacitor and the output electrode, and the output end of the third operational amplifier circuit is connected to the receiving end.

7. The current output circuit according to claim 6, characterized in that: The first operational amplifier unit includes a first amplifier, a fourth resistor, a fifth resistor, a sixth resistor and a seventh resistor; The non-inverting input terminal of the first amplifier is connected to the second control terminal; The inverting input terminal of the first amplifier is connected to the positive power supply terminal of the DC power supply through the fourth resistor and the fifth resistor, one end of the sixth resistor is connected between the fourth resistor and the fifth resistor, and the other end is connected to the negative power supply terminal of the DC power supply; The output end of the first amplifier is connected to the second operational amplifier unit, and the seventh resistor is further connected between the output end and the inverting input end.

8. The current output circuit according to claim 7, characterized in that: A filtering unit is connected between the in-phase input terminal of the first amplifier and the second control terminal.

9. The current output circuit according to claim 6, characterized in that: The second operational amplifier unit includes a second amplifier and an eighth resistor; The non-inverting input terminal of the second amplifier is connected to the first operational amplifier unit through the eighth resistor; An inverting input terminal of the second amplifier is connected to the output terminal of the second amplifier and to the input electrode.

10. The current output circuit according to claim 6, characterized in that: The third operational amplifier circuit includes a third amplifier, a ninth resistor and a tenth resistor; The non-inverting input terminal of the third amplifier is connected between the detection capacitor and the output electrode through the ninth resistor; The inverting input terminal of the third amplifier is connected to the output terminal of the third amplifier and is connected to the receiving terminal through the tenth resistor.

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