Electrical stimulation intermediate frequency output circuit

Abstract

The utility model discloses an electrical stimulation intermediate frequency output circuit, comprising an isolation power supply used for supplying power to the intermediate frequency output circuit; the MCU micro-control unit outputs a pair of control signals which are used for controlling connection and disconnection of an H-bridge output circuit in the intermediate frequency output circuit and further controlling the stimulating electrode to output positive pulse and negative pulse and close output. The MCU micro-control unit generates two paths of analog voltage signals by using an internal DAC (Digital-to-Analog Converter) and is used for controlling the output voltage and the output stimulation current of a BOOST circuit in the intermediate-frequency output circuit; the MCU uses an internal ADC to collect the magnitude of voltage output to the stimulating electrode and the magnitude of output stimulating current. According to the utility model, the voltage-controlled constant current source circuit is adopted to control the output of electrical stimulation, and the micro-control unit is adopted to receive feedback in real time and calibrate and compensate the output, so that the output waveform precision of the electrical stimulation and the consistency and stability of the output stimulation current can be effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of electric stimulation, in particular to an electric stimulation intermediate frequency output circuit. Background Art

[0002] Electrical stimulation refers to the use of electric current to stimulate the body, using different forms of electric current to enhance muscle contraction, restore functional movement and increase strength. In current bioelectric stimulation applications, due to the large differences in impedance and capacitance between different biological individuals and different parts of biological tissues, the contact area and contact impedance of the stimulation electrodes are also very different. Using a fixed stimulation voltage or a stimulation voltage with poor real-time performance will result in the inability to accurately control the stimulation current, the circuit will not be able to effectively receive current feedback, and the user experience will be poor. Utility Model Content

[0003] Technical purpose: In view of the defects in the prior art, the utility model discloses an electric stimulation intermediate frequency output circuit, which adopts a voltage-controlled constant current source circuit to control the output of electric stimulation, and adopts a micro control unit to realize real-time reception of feedback, calibration and compensation of the output, which can effectively improve the output waveform accuracy of electric stimulation, and the consistency and stability of the output stimulation current.

[0004] Technical solution: In order to achieve the above technical objectives, the utility model adopts the following technical solution.

[0005] An electric stimulation intermediate frequency output circuit comprises an MCU microcontroller unit, an intermediate frequency output circuit and an isolated power supply connected one by one; the isolated power supply is used to supply power to the intermediate frequency output circuit;

[0006] The MCU microcontroller unit outputs a pair of control signals for controlling the conduction and cutoff of the H-bridge output circuit in the intermediate frequency output circuit, thereby controlling the stimulation electrode to output positive pulses, negative pulses, and turn off the output;

[0007] The MCU microcontroller unit uses the internal DAC to generate two analog voltage signals, one for controlling the output voltage of the BOOST boost circuit in the intermediate frequency output circuit, and the other for controlling the output stimulation current of the intermediate frequency output circuit;

[0008] The MCU microcontroller unit uses the internal ADC to collect the voltage output to the stimulation electrode and the output stimulation current.

[0009] Preferably, the MCU microcontroller unit includes an MCU control chip U4, wherein pin 27 of the MCU control chip U4 outputs a STIM_CTL+ signal, and pin 28 of the MCU control chip U4 outputs a STIM_CTL- signal, which are used to control the conduction and cutoff of the H-bridge output circuit in the intermediate frequency output circuit; pin 14 of the MCU control chip U4 outputs a voltage control signal, namely, STIM_VoltageCTL, which is used to control the output voltage of the BOOST boost circuit in the intermediate frequency output circuit; pin 15 of the MCU control chip U4 outputs a current control signal, namely, STIM_CurrentCTL, which is used to control the current detection circuit in the intermediate frequency output circuit to output the stimulation current; pin 11 of the MCU control chip U4 receives a voltage detection signal, namely, a STIM_VoltageDET signal, and pin 17 of the MCU control chip U4 receives a current detection signal, namely, a STIM_CurrentDET signal, and uses an internal ADC to collect the voltage output to the stimulation electrode and the output stimulation current.

[0010] Preferably, the intermediate frequency output circuit includes an H-bridge output circuit, an H-bridge control circuit and a BOOST boost circuit;

[0011] The H-bridge output circuit comprises a transistor Q1, a transistor Q2, a MOS transistor Q3 and a MOS transistor Q4, the base of the transistor Q1 is connected to the emitter of the transistor Q1 through a resistor R4, the emitter of the transistor Q1 is connected to the emitter of the transistor Q2, the emitter of the transistor Q2 is connected to the base of the transistor Q2 through a resistor R5, the collector of the transistor Q1 outputs an OUT+ signal, the collector of the transistor Q2 outputs an OUT- signal, and the OUT+ signal and the OUT- signal are used to control the stimulation electrode; the transistor Q The collector of transistor Q1 is connected to the drain of MOS tube Q3, the collector of transistor Q2 is connected to the drain of MOS tube Q4, the gate of MOS tube Q3 is connected to the HLLC signal, that is, the positive terminal signal of diode D2 in the H-bridge control circuit, the gate of MOS tube Q4 is connected to the HLRC signal, that is, the positive terminal signal of diode D1 in the H-bridge control circuit, the source of MOS tube Q3 is connected to the source of MOS tube Q4, and is grounded through resistor R1; the connection point of the source of MOS tube Q3 and the source of MOS tube Q4 is point A;

[0012] The H-bridge control circuit includes a transistor Q5, a transistor Q6, a MOS transistor Q7 and a MOS transistor Q8; the collector of the transistor Q5 is connected to the base of the transistor Q1, the emitter of the transistor Q5 is grounded through a resistor R8, the base of the transistor Q5 is connected to the negative terminal of the diode D1, and the positive terminal of the diode D1 is connected to the emitter of the transistor Q5; the collector of the transistor Q6 is connected to the base of the transistor Q2, the emitter of the transistor Q6 is grounded through a resistor R9, the base of the transistor Q6 is connected to the diode D2 The negative terminal of the diode D2 is connected to the emitter of the transistor Q6; the base of the transistor Q5 is connected to the base of the transistor Q6 through the resistor R6 and the resistor R7; the base of the transistor Q5 is connected to the drain of the MOS transistor Q7, the source of the MOS transistor Q7 is grounded, and the gate of the MOS transistor Q7 is connected to the STIM_CTL+ signal; the base of the transistor Q6 is connected to the drain of the MOS transistor Q8, the source of the MOS transistor Q8 is grounded, and the gate of the MOS transistor Q8 is connected to the STIM_CTL- signal;

[0013] The BOOST boost circuit includes a BOOST module, the input end of the BOOST module is a 12V power supply, i.e., an isolated power supply, the output end of the BOOST module is a 12V~78V power supply, and the control end of the BOOST module is a voltage control signal, i.e., STIM_VoltageCTL; the output end of the BOOST module is connected to the emitter of the transistor Q1 and the emitter of the transistor Q2;

[0014] The two ends of the stimulation electrode are connected to the OUT+ signal and the OUT- signal respectively, and the two ends of the stimulation electrode are grounded through the switch S1 and the switch S2 respectively. The switch S1 and the switch S2 are simplified forms of the stimulation voltage discharge circuit.

[0015] Preferably, the utility model also includes a current detection circuit, which includes an op amp U1 and an op amp U2, wherein the output end of the op amp U1 is connected to the base of the transistor Q6 through a resistor R7, and the output end of the op amp U1 is connected to the base of the transistor Q5 through a resistor R6; the non-inverting input end of the op amp U1 inputs a current control signal, i.e., a STIM_CurrentCTL signal, the inverting input end of the op amp U1 is connected to a 3.3V voltage through a resistor R3, and the inverting input end of the op amp U1 is connected to point A through a resistor R2; the output end of the op amp U2 outputs a current detection signal, i.e., a STIM_CurrentDET signal, the inverting input end of the op amp U2 is connected to the output end of the op amp U2, and the non-inverting input end of the op amp U2 is connected to point A through a resistor R10, and the op amp U1 in the current detection circuit, the H-bridge control circuit, and the H-bridge output circuit constitute a voltage-controlled constant current source circuit.

[0016] Preferably, the utility model also includes a voltage detection circuit, which includes an op amp U3, the OUT+ signal and the OUT- signal at the two ends of the stimulation electrode are respectively connected to the cathode terminal of the diode D3 and the cathode terminal of the diode D4, the positive terminal of the diode D3 and the positive terminal of the diode D4 are connected to the in-phase input terminal of the op amp U3 through a resistor R27, the in-phase input terminal of the op amp U3 is grounded through a resistor R28, the inverting input terminal of the op amp U3 is connected to the output terminal of the op amp U3, and the output terminal of the op amp U3 outputs the STIM_VoltageDET signal.

[0017] Preferably, the utility model also includes a stimulation voltage discharge circuit, which includes a MOS tube Q21 and a MOS tube Q22, the drain of the MOS tube Q21 is connected to the OUT+ signal through a resistor R21, the source of the MOS tube Q21 is grounded, the gate of the MOS tube Q21 is grounded through a resistor R23, and the gate of the MOS tube Q21 is connected to the LEAKAGE+ signal through a resistor R22, that is, the left bridge arm discharge control signal; the drain of the MOS tube Q22 is connected to the OUT- signal through a resistor R24, the source of the MOS tube Q22 is grounded, the gate of the MOS tube Q22 is grounded through a resistor R26, and the gate of the MOS tube Q22 is connected to the LEAKAGE- signal through a resistor R25, that is, the right bridge arm discharge control signal, and the pin 41 of the MCU control chip U4 outputs the LEAKAGE+ signal and the LEAKAGE- signal, and the LEAKAGE+ signal and the LEAKAGE- signal respectively discharge the charges on the OUT+ signal and the OUT- signal at both ends of the stimulation electrode.

[0018] Beneficial effects: The utility model adopts a voltage-controlled constant current source circuit to control the output of electrical stimulation, and adopts a microcontroller unit to receive feedback in real time, calibrate and compensate the output, which can effectively improve the output waveform accuracy of electrical stimulation, and the consistency and stability of the output stimulation current. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the module of the utility model;

[0020] Figure 2 It is a circuit diagram of the intermediate frequency output circuit of the utility model;

[0021] Figure 3 This is a schematic diagram of stimulation voltage detection of the utility model;

[0022] Figure 4 This is a schematic diagram of the stimulation voltage discharge of the utility model;

[0023] Figure 5 It is a schematic diagram of the signal processing flow of the utility model;

[0024] Figure 6 This is a schematic diagram of the stimulation voltage control logic of the utility model;

[0025] Figure 7 It is a schematic diagram of the stimulation voltage output waveform of the utility model;

[0026] Figure 8 This is a schematic diagram of the MCU micro control unit circuit of the utility model;

[0027] Fig. 9 It is a partial circuit diagram of other alternative embodiments of the utility model. DETAILED DESCRIPTION

[0028] The following is a further description and explanation of an electric stimulation intermediate frequency output circuit of the present invention in conjunction with the accompanying drawings.

[0029] As attached Figure 1 As shown, an electric stimulation intermediate frequency output circuit of the utility model includes an MCU microcontroller unit, an intermediate frequency output circuit and an isolated power supply connected one by one; the isolated power supply is used to power the intermediate frequency output circuit;

[0030] The MCU microcontroller unit outputs a pair of control signals for controlling the on and off of the H-bridge output circuit in the intermediate frequency output circuit, thereby controlling the stimulation electrode to output positive pulses, negative pulses, and shut down the output.

[0031] The MCU microcontroller unit uses the internal DAC to generate two analog voltage signals, one for controlling the output voltage of the BOOST boost circuit in the intermediate frequency output circuit, and the other for controlling the output stimulation current of the intermediate frequency output circuit.

[0032] The MCU microcontroller unit uses the internal ADC to collect the voltage output to the stimulation electrode and the output stimulation current.

[0033] As attached Figure 8As shown, the MCU microcontroller unit includes an MCU control chip U4, and the model of the MCU control chip U4 is GD32F303CCT6; pins 9, 24, 36 and 48 of the MCU control chip U4 are connected to a 3.3V voltage, and pins 8, 23, 35 and 47 of the MCU control chip U4 are grounded; pin 27 of the MCU control chip U4 outputs a STIM_CTL+ signal, and pin 28 of the MCU control chip U4 outputs a STIM_CTL- signal, which is used to control the conduction and cutoff of the H-bridge output circuit in the intermediate frequency output circuit; pin 14 of the MCU control chip U4 outputs a voltage control signal, i.e., S TIM_VoltageCTL is used to control the output voltage of the BOOST boost circuit in the intermediate frequency output circuit; Pin 15 of the MCU control chip U4 outputs a current control signal, namely STIM_CurrentCTL, which is used to control the current detection circuit in the intermediate frequency output circuit to output a stimulation current; Pin 11 of the MCU control chip U4 receives a voltage detection signal, namely the STIM_VoltageDET signal, and Pin 17 of the MCU control chip U4 receives a current detection signal, namely the STIM_CurrentDET signal, and uses the internal ADC to collect the voltage output to the stimulation electrode and the output stimulation current. Pin 41 of the MCU control chip U4 outputs LEAKAGE+ and LEAKAGE- signals, which discharge the charges on the OUT+ and OUT- signals at both ends of the stimulation electrode, respectively.

[0034] As attached Figure 2 As shown, the intermediate frequency output circuit includes an H-bridge output circuit, an H-bridge control circuit, a current detection circuit, a voltage detection circuit, a stimulus voltage discharge circuit and a BOOST boost circuit;

[0035] The H-bridge output circuit includes a transistor Q1, a transistor Q2, a MOS transistor Q3 and a MOS transistor Q4, and the transistors Q1, Q2, Q3 and Q4 form an H-bridge; the base of the transistor Q1 is connected to the emitter of the transistor Q1 through a resistor R4, the emitter of the transistor Q1 is connected to the emitter of the transistor Q2, the emitter of the transistor Q2 is connected to the base of the transistor Q2 through a resistor R5, the collector of the transistor Q1 outputs an OUT+ signal, the collector of the transistor Q2 outputs an OUT- signal, and the OUT+ signal and the OUT- signal are used to control the stimulation electrode; the collector of the transistor Q1 is connected to the MOS transistor The drain of Q3 is connected, the collector of the triode Q2 is connected to the drain of the MOS tube Q4, the gate of the MOS tube Q3 is connected to the HLLC signal, that is, the positive terminal signal of the diode D2 in the H-bridge control circuit, the gate of the MOS tube Q4 is connected to the HLRC signal, that is, the positive terminal signal of the diode D1 in the H-bridge control circuit, the source of the MOS tube Q3 is connected to the source of the MOS tube Q4, and is grounded through the resistor R1; the connection point of the source of the MOS tube Q3 and the source of the MOS tube Q4 is point A; wherein, the model of the triode Q1 and the triode Q2 is FZT955; the model of the MOS tube Q3 and the MOS tube Q4 is BSS123;

[0036] The H-bridge control circuit includes a transistor Q5, a transistor Q6, a MOS transistor Q7 and a MOS transistor Q8; the collector of the transistor Q5 is connected to the base of the transistor Q1, the emitter of the transistor Q5 is grounded through a resistor R8, the base of the transistor Q5 is connected to the negative terminal of the diode D1, and the positive terminal of the diode D1 is connected to the emitter of the transistor Q5; the collector of the transistor Q6 is connected to the base of the transistor Q2, the emitter of the transistor Q6 is grounded through a resistor R9, the base of the transistor Q6 is connected to the negative terminal of the diode D2, the positive terminal of the diode D2 is connected to the emitter of the transistor Q6 connection; the base of transistor Q5 is connected to the base of transistor Q6 through resistor R6 and resistor R7; the base of transistor Q5 is connected to the drain of MOS tube Q7, the source of MOS tube Q7 is grounded, and the gate of MOS tube Q7 is connected to STIM_CTL+ signal; the base of transistor Q6 is connected to the drain of MOS tube Q8, the source of MOS tube Q8 is grounded, and the gate of MOS tube Q8 is connected to STIM_CTL- signal; wherein, the model of transistor Q5 and transistor Q6 is MMBT5551; the model of MOS tube Q7 and MOS tube Q8 is 2N7002K;

[0037] The BOOST boost circuit includes a BOOST module, the input end of the BOOST module is a 12V power supply, i.e., an isolated power supply, the output end of the BOOST module is a 12V~78V power supply, and the control end of the BOOST module is a voltage control signal, i.e., STIM_VoltageCTL; the output end of the BOOST module is connected to the emitter of the transistor Q1 and the emitter of the transistor Q2;

[0038] The two ends of the stimulation electrode are connected to the OUT+ signal and the OUT- signal respectively, and the two ends of the stimulation electrode are grounded through the switch S1 and the switch S2 respectively; the switch S1 and the switch S2 are simplified forms of the stimulation voltage discharge circuit;

[0039] The working principle of the H-bridge control circuit is: the signals STIM_CTL+ and STIM_CTL- output by the MCU microcontroller control the on and off of the H-bridge output circuit.

[0040] As attached Figure 6 As shown in the figure, when STIM_CTL+ is 3.3V high level and STIM_CTL- is 0V low level, on the left bridge arm, MOS tube Q7 is turned on; at this time, both ends of diode D1 and the base of transistor Q5 become low level, transistor Q5 is turned off, MOS field effect tube Q4 is turned off, and the base of Q1 is turned off at a high level; on the right bridge arm, MOS tube Q8 is turned off, and the op amp U1 and H bridge and other devices form a voltage-controlled constant current source circuit. In order to make the voltage of the in-phase input terminal and the inverting input terminal equal, the output terminal voltage will be adjusted, and the current passing through the H bridge will be automatically adjusted to make the entire circuit tend to a stable state. Both ends of diode D2 and the base of transistor Q6 are controlled by op amp U1 to become high level, transistor Q6 is turned on, MOS tube Q3 is turned on, and the base of Q2 is turned on at a low level. At this time, the BOOST output current flows to the negative electrode of the stimulation electrode through the transistor Q2, passes through the stimulation electrode, flows to the positive electrode of the stimulation electrode, and passes through the MOS tube Q3 and the resistor R1 and returns to the ground. At this time, the stimulation electrode outputs a negative pulse.

[0041] When STIM_CTL+ is 0V low level and STIM_CTL- is 3.3V high level, on the right bridge arm, MOS tube Q8 is turned on; at this time, both ends of diode D2 and the base of transistor Q6 are at low level, transistor Q6 is cut off, MOS tube Q3 is cut off, and the base of Q2 is cut off at a high level; on the left bridge arm, MOS tube Q7 is cut off, both ends of diode D1 and the base of transistor Q5 are controlled by U1 to become high level, transistor Q5 is turned on, MOS field effect tube Q4 is turned on, and the base of Q1 is turned on at a low level; at this time, the BOOST output current flows to the positive electrode of the stimulation electrode through the transistor Q1, passes through the stimulation electrode, flows to the negative electrode of the stimulation electrode, and passes through the MOS tube Q4 and the resistor R1 and returns to the ground. At this time, the stimulation electrode outputs a positive pulse.

[0042] When STIM_CTL+ and STIM_CTL- are both at a high level of 3.3V, transistors Q1, Q2, MOS Q3 and Q4 of the H-bridge output circuit are all in the cut-off state, and no stimulation current is output.

[0043] The current detection circuit includes an op amp U1 and an op amp U2. The model of the op amp U1 is SGM8270-2XMS8G / TR, and the model of the op amp U2 is SGM8544XTS14 / TR. The output end of the op amp U1 is connected to the base of the transistor Q6 through the resistor R7, and the output end of the op amp U1 is connected to the base of the transistor Q5 through the resistor R6. The current control signal, i.e., the STIM_CurrentCTL signal, is input to the in-phase input end of the op amp U1. 1 is connected to a 3.3V voltage through a resistor R3, and the inverting input terminal of the operational amplifier U1 is connected to point A through a resistor R2; the output terminal of the operational amplifier U2 outputs a current detection signal, namely, a STIM_CurrentDET signal, the inverting input terminal of the operational amplifier U2 is connected to the output terminal of the operational amplifier U2, and the non-inverting input terminal of the operational amplifier U2 is connected to point A through a resistor R10; wherein, the operational amplifier U1 in the current detection circuit, the H-bridge control circuit, and the H-bridge output circuit constitute a voltage-controlled constant current source circuit;

[0044] In the voltage-controlled constant current source circuit, the working principle of the stimulation current control of the stimulation electrode is as follows: when current control is performed, the MCU microcontroller unit uses the internal DAC to output the STIM_CurrentCTL signal to the in-phase input terminal of the op amp U1, that is, outputs a voltage V c To the non-inverting input of op amp U1, V c It is an analog voltage with a range of 0~3.3V, V c Dynamically changes to adjust the current; at this time, the voltage V + =V c ; The output of the operational amplifier U1 passes through the feedback network and enters the inverting input terminal of the operational amplifier U1, forming a negative feedback; wherein, when the stimulation electrode outputs a positive pulse, the feedback network is resistor R6, H-bridge control circuit, H-bridge output circuit and resistor R2, and the output of the operational amplifier U1 returns to the inverting input terminal of the operational amplifier U1 via resistor R6, H-bridge control circuit, H-bridge output circuit and resistor R2; when the stimulation electrode outputs a negative pulse, the feedback network is resistor R7, H-bridge control circuit, H-bridge output circuit and resistor R2, and the output of the operational amplifier U1 returns to the inverting input terminal of the operational amplifier U1 via resistor R7, H-bridge control circuit, H-bridge output circuit and resistor R2. According to the virtual short principle of the operational amplifier, the voltage V at the inverting input terminal of the operational amplifier U1 - =V +According to the virtual disconnection principle of the op amp, the current of the 3.3V power supply will only flow to point A through resistors R3 and R2, and will not enter the inverting input terminal of the op amp U1. The current of the 3.3V power supply through resistors R3 and R2 is equal, that is, I3=I2; at this time, the voltage V - =3.3V-I3*R3; voltage at point A: V A =V - -I2*R2; finally, the voltage at point A is simplified to: V A =V c -R2*(3.3VV c ) / R3=I1*R1, the current flowing through resistor R1 is the stimulation current, so the stimulation current: I=I1=V c / R1-R2*(3.3VV c ) / (R3*R1); the resistors R1, R2, and R3 are fixed values, so the voltage of STIM_CurrentCTL, that is, V c Control the magnitude of the stimulation current.

[0045] In the current detection circuit, the working principle of the stimulation current detection of the stimulation electrode is: resistor R10 is connected to point A and input to the non-inverting input terminal of the operational amplifier U2. The voltage at the non-inverting input terminal of the operational amplifier U2 is the voltage at point A. The operational amplifier U2 acts as a voltage follower and inputs the voltage at point A to the MCU microcontroller unit through STIM_CurrentDET. The ADC of the MCU microcontroller unit is used to collect the voltage to obtain the voltage Vd. The actual output stimulation current is Io=Vd / R1.

[0046] As attached Figure 3 As shown, the voltage detection circuit includes an op amp U3, and the model of the op amp U3 is SGM8544XTS14 / TR; the OUT+ signal and the OUT- signal at both ends of the stimulation electrode are respectively connected to the cathode terminal of the diode D3 and the cathode terminal of the diode D4, the anode terminal of the diode D3 and the anode terminal of the diode D4 are connected to the in-phase input terminal of the op amp U3 through the resistor R27, the in-phase input terminal of the op amp U3 is grounded through the resistor R28, the inverting input terminal of the op amp U3 is connected to the output terminal of the op amp U3, and the output terminal of the op amp U3 outputs a voltage detection signal, that is, a STIM_VoltageDET signal;

[0047] The working principle of the voltage detection circuit is as follows: the operational amplifier U3 acts as a voltage follower. When the stimulation current of the stimulation electrode is output, when a positive pulse is output, the OUT+ signal passes through the diode D3, and is divided by resistors R27 and R28 to a voltage suitable for ADC collection in the MCU microcontroller unit. After passing through the operational amplifier U3, the ADC detects STIM_VoltageDET, and the stimulation voltage can be collected; when a negative pulse is output, the OUT- signal passes through the diode D4, and is divided by resistors R27 and R28 to a voltage suitable for ADC collection. After passing through the operational amplifier U3, the ADC detects STIM_VoltageDET, and the stimulation voltage can be collected.

[0048] As attached Figure 4 As shown, the stimulation voltage discharge circuit includes a MOS tube Q21 and a MOS tube Q22, the drain of the MOS tube Q21 is connected to the OUT+ signal through a resistor R21, the source of the MOS tube Q21 is grounded, the gate of the MOS tube Q21 is grounded through a resistor R23, and the gate of the MOS tube Q21 is connected to the LEAKAGE+ signal through a resistor R22, that is, the left bridge arm discharge control signal; the drain of the MOS tube Q22 is connected to the OUT- signal through a resistor R24, the source of the MOS tube Q22 is grounded, the gate of the MOS tube Q22 is grounded through a resistor R26, and the gate of the MOS tube Q22 is connected to the LEAKAGE- signal through a resistor R25, that is, the right bridge arm discharge control signal;

[0049] The working principle of the stimulation voltage discharge circuit is: when the stimulation ends, the MCU microcontroller unit discharges the charges on the OUT+ signal and OUT- signal at both ends of the stimulation electrode through the LEAKAGE+ signal and LEAKAGE- signal respectively, thereby protecting the stimulation electrode and preventing electrochemical corrosion of the stimulation electrode.

[0050] like Figure 5As shown, when an electric stimulation intermediate frequency output circuit of the utility model controls the stimulation electrode to emit a group of positive and negative pulses, the working process is as follows: the MCU microcontroller presets a voltage for the BOOST boost circuit through the STIM_VoltageCTL signal, opens the left bridge arm, and the current passes through the triode Q1, the stimulation electrode, the MOS tube Q4 and the resistor R1 respectively, and then flows into the ground. Secondly, the stimulation current is set by the STIM_CurrentCTL signal, and the stimulation current of the stimulation electrode is detected by the current detection circuit. If it does not meet the set value, the voltage value of the STIM_CurrentCTL signal is readjusted. If it meets the set current value, the output voltage is detected by the voltage detection circuit to see if it meets the requirements. If not, the output voltage of the BOOST boost circuit is adjusted by the STIM_VoltageCTL signal. If it meets, wait for the positive pulse output to be completed, and close the left bridge arm to discharge the OUT+ and OUT- charges. Wait for the interval time between the set positive and negative pulses, open the right bridge arm, and start outputting negative pulses. After the negative pulse output is completed, close the right bridge arm, discharge the OUT+ and OUT- charges, and close the voltage output of the BOOST boost circuit. The intermediate frequency output cycle in the utility model refers to the time between one group of positive and negative pulses and the next group of positive and negative pulses.

[0051] In order to ensure the stability of the output stimulation current, the utility model adopts a voltage-controlled constant current source circuit to control the output of electrical stimulation. A microcontroller unit is used to receive feedback in real time, calibrate and compensate the output. During biological stimulation, the impedance and capacitance of the organism will change dynamically, and the stimulation circuit adjusts the output stimulation intensity according to the detection results. It can effectively improve the output waveform accuracy of electrical stimulation, the consistency and stability of the output stimulation current, and realize accurate control of the output current size, output pulse width, intermediate frequency pulse frequency, polarity, and stimulation waveform.

[0052] As attached Figure 7 As shown, the use example of the utility model is: set the output current to 20mA, the intermediate frequency output frequency to 5KHz, connect a 500Ω resistor at both ends of the stimulation output OUT+ and OUT-, and use an oscilloscope to measure the voltage at both ends of OUT+ and OUT-. The stimulation circuit can correctly output positive and negative pulses.

[0053] In some other embodiments of the present invention, Fig. 9 As shown, transistor Q1 and transistor Q5 can be replaced by an NPN transistor or a field effect transistor; transistor Q2 and transistor Q6 can be replaced by an NPN transistor or a field effect transistor; at this time, the H-bridge control circuit and the H-bridge output circuit require 4 signals for switch control; the 3.3V power supply can be replaced by other voltages;

[0054] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. An electrical stimulation intermediate frequency output circuit, characterized in that: It includes an MCU micro control unit, an intermediate frequency output circuit and an isolated power supply which are connected one by one; the isolated power supply is used to supply power to the intermediate frequency output circuit; The MCU microcontroller unit outputs a pair of control signals for controlling the conduction and cutoff of the H-bridge output circuit in the intermediate frequency output circuit, thereby controlling the stimulation electrode to output positive pulses, negative pulses, and turn off the output; The MCU microcontroller unit uses the internal DAC to generate two analog voltage signals, one for controlling the output voltage of the BOOST boost circuit in the intermediate frequency output circuit, and the other for controlling the output stimulation current of the intermediate frequency output circuit; The MCU microcontroller unit uses the internal ADC to collect the voltage output to the stimulation electrode and the output stimulation current.

2. An electrical stimulation intermediate frequency output circuit according to claim 1, characterized in that: The MCU microcontroller unit includes an MCU control chip U4, wherein pin 27 of the MCU control chip U4 outputs a STIM_CTL+ signal, and pin 28 of the MCU control chip U4 outputs a STIM_CTL- signal, which are used to control the conduction and cutoff of the H-bridge output circuit in the intermediate frequency output circuit; pin 14 of the MCU control chip U4 outputs a voltage control signal, namely, STIM_VoltageCTL, which is used to control the output voltage of the BOOST boost circuit in the intermediate frequency output circuit; pin 15 of the MCU control chip U4 outputs a current control signal, namely, STIM_CurrentCTL, which is used to control the current detection circuit in the intermediate frequency output circuit to output a stimulation current; pin 11 of the MCU control chip U4 receives a voltage detection signal, namely, a STIM_VoltageDET signal, and pin 17 of the MCU control chip U4 receives a current detection signal, namely, a STIM_CurrentDET signal, and uses an internal ADC to collect the voltage output to the stimulation electrode and the output stimulation current.

3. An electric stimulation intermediate frequency output circuit according to claim 2, characterized in that: The intermediate frequency output circuit includes an H-bridge output circuit, an H-bridge control circuit and a BOOST boost circuit; The H-bridge output circuit comprises a transistor Q1, a transistor Q2, a MOS transistor Q3 and a MOS transistor Q4, the base of the transistor Q1 is connected to the emitter of the transistor Q1 through a resistor R4, the emitter of the transistor Q1 is connected to the emitter of the transistor Q2, the emitter of the transistor Q2 is connected to the base of the transistor Q2 through a resistor R5, the collector of the transistor Q1 outputs an OUT+ signal, the collector of the transistor Q2 outputs an OUT- signal, and the OUT+ signal and the OUT- signal are used to control the stimulation electrode; the transistor Q The collector of transistor Q1 is connected to the drain of MOS tube Q3, the collector of transistor Q2 is connected to the drain of MOS tube Q4, the gate of MOS tube Q3 is connected to the HLLC signal, that is, the positive terminal signal of diode D2 in the H-bridge control circuit, the gate of MOS tube Q4 is connected to the HLRC signal, that is, the positive terminal signal of diode D1 in the H-bridge control circuit, the source of MOS tube Q3 is connected to the source of MOS tube Q4, and is grounded through resistor R1; the connection point of the source of MOS tube Q3 and the source of MOS tube Q4 is point A; The H-bridge control circuit includes a transistor Q5, a transistor Q6, a MOS transistor Q7 and a MOS transistor Q8; the collector of the transistor Q5 is connected to the base of the transistor Q1, the emitter of the transistor Q5 is grounded through a resistor R8, the base of the transistor Q5 is connected to the negative terminal of the diode D1, and the positive terminal of the diode D1 is connected to the emitter of the transistor Q5; the collector of the transistor Q6 is connected to the base of the transistor Q2, the emitter of the transistor Q6 is grounded through a resistor R9, the base of the transistor Q6 is connected to the diode D2 The negative terminal of the diode D2 is connected to the emitter of the transistor Q6; the base of the transistor Q5 is connected to the base of the transistor Q6 through the resistor R6 and the resistor R7; the base of the transistor Q5 is connected to the drain of the MOS transistor Q7, the source of the MOS transistor Q7 is grounded, and the gate of the MOS transistor Q7 is connected to the STIM_CTL+ signal; the base of the transistor Q6 is connected to the drain of the MOS transistor Q8, the source of the MOS transistor Q8 is grounded, and the gate of the MOS transistor Q8 is connected to the STIM_CTL- signal; The BOOST boost circuit includes a BOOST module, the input end of the BOOST module is a 12V power supply, i.e., an isolated power supply, the output end of the BOOST module is a 12V~78V power supply, and the control end of the BOOST module is a voltage control signal, i.e., STIM_VoltageCTL; the output end of the BOOST module is connected to the emitter of the transistor Q1 and the emitter of the transistor Q2; The two ends of the stimulation electrode are connected to the OUT+ signal and the OUT- signal respectively, and the two ends of the stimulation electrode are grounded through the switch S1 and the switch S2 respectively. The switch S1 and the switch S2 are simplified forms of the stimulation voltage discharge circuit.

4. An electric stimulation intermediate frequency output circuit according to claim 3, characterized in that: It also includes a current detection circuit, which includes an operational amplifier U1 and an operational amplifier U2. The output end of the operational amplifier U1 is connected to the base of the transistor Q6 through a resistor R7, and the output end of the operational amplifier U1 is connected to the base of the transistor Q5 through a resistor R6; the non-inverting input end of the operational amplifier U1 inputs a current control signal, namely, a STIM_CurrentCTL signal, the inverting input end of the operational amplifier U1 is connected to a 3.3V voltage through a resistor R3, and the inverting input end of the operational amplifier U1 is connected to a point A through a resistor R2; the output end of the operational amplifier U2 outputs a current detection signal, namely, a STIM_CurrentDET signal, the inverting input end of the operational amplifier U2 is connected to the output end of the operational amplifier U2, and the non-inverting input end of the operational amplifier U2 is connected to a point A through a resistor R10. The operational amplifier U1 in the current detection circuit, the H-bridge control circuit, and the H-bridge output circuit constitute a voltage-controlled constant current source circuit.

5. The electric stimulation intermediate frequency output circuit according to claim 4, characterized in that: It also includes a voltage detection circuit, which includes an operational amplifier U3. The OUT+ signal and the OUT- signal at the two ends of the stimulation electrode are respectively connected to the cathode terminal of the diode D3 and the cathode terminal of the diode D4. The positive terminal of the diode D3 and the positive terminal of the diode D4 are connected to the in-phase input terminal of the operational amplifier U3 through a resistor R27. The in-phase input terminal of the operational amplifier U3 is grounded through a resistor R28. The inverting input terminal of the operational amplifier U3 is connected to the output terminal of the operational amplifier U3. The output terminal of the operational amplifier U3 outputs the STIM_VoltageDET signal.

6. The electric stimulation intermediate frequency output circuit according to claim 3, characterized in that: The device also includes a stimulation voltage discharge circuit, which includes a MOS tube Q21 and a MOS tube Q22. The drain of the MOS tube Q21 is connected to the OUT+ signal through a resistor R21, the source of the MOS tube Q21 is grounded, the gate of the MOS tube Q21 is grounded through a resistor R23, and the gate of the MOS tube Q21 is connected to the LEAKAGE+ signal through a resistor R22, that is, the left bridge arm discharge control signal; the drain of the MOS tube Q22 is connected to the OUT- signal through a resistor R24, the source of the MOS tube Q22 is grounded, the gate of the MOS tube Q22 is grounded through a resistor R26, and the gate of the MOS tube Q22 is connected to the LEAKAGE- signal through a resistor R25, that is, the right bridge arm discharge control signal. The pin 41 of the MCU control chip U4 outputs the LEAKAGE+ signal and the LEAKAGE- signal, and the LEAKAGE+ signal and the LEAKAGE- signal respectively discharge the charges on the OUT+ signal and the OUT- signal at both ends of the stimulation electrode.

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