Electrode impedance test system for physical therapy

Abstract

The invention provides an electrode impedance test system for physical therapy. The electrode impedance test system comprises a microcontroller, a D / A conversion circuit, a power amplification circuit, a voltage detection circuit, a current detection circuit and a boosting transformer circuit. The microcontroller generates a square wave signal, the square wave signal is converted into a sinusoidal signal through the D / A conversion circuit, and the sinusoidal signal is amplified through the power amplification circuit. The boosting transformer transmits the amplified sinusoidal signal to the electrode slice, and the secondary side of the boosting transformer is connected with the voltage and current sampling circuit and is used for collecting a differential signal. According to the system, the electrode impedance of the electrode plates is detected through voltage and current sampling of the pair of electrode plates, common-mode interference and signal distortion are eliminated through the differential signal amplification circuit and the full-wave precision rectification circuit, and high-precision acquisition and detection of signals are ensured. The detected and rectified signals are converted into digital signals through the A / D conversion circuit, and the digital signals are input into the signal input end of the microcontroller.

Description

Technical Field

[0001] The invention belongs to the technical field of electrode impedance testing, and in particular relates to an electrode impedance testing system for physical therapy. Background Art

[0002] Electrode impedance testing is an important technical means to evaluate electrode performance and quality. However, the existing technical means are to use a signal generator, a multimeter, an oscilloscope, a wiring interface device, and an electrode sheet clamping device to jointly achieve the measurement of electrode sheet electrode impedance. The experimental process requires a large number of instruments and equipment, and the operation is complicated, and multiple people are required to complete the measurement. Summary of the invention

[0003] To solve the above problems, the present invention provides an electrode impedance testing system for physical therapy, which can replace the existing measurement methods (signal generator, multimeter, oscilloscope, wiring interface device, electrode sheet pressing device), greatly simplifies the complexity of the test and improves the efficiency of the test.

[0004] The solution of the present invention to solve the technical problem is: adopt an electrode impedance test system for physical therapy, including a microcontroller, a D / A conversion circuit, a power amplifier circuit, a voltage detection circuit and a current detection circuit, and a step-up transformer circuit. Among them, the microcontroller: as the control center of the system, outputs a square wave signal; the D / A conversion circuit: converts the square wave signal output by the microcontroller into a sine signal; the power amplifier circuit: amplifies the power of the sine signal; the step-up transformer circuit: the primary side is connected to the sine signal processed by the front end, the secondary side is connected to the electrode sheet for testing, and the secondary side is connected to the output voltage sampling differential input signal and the current sampling differential input signal; the voltage sampling circuit: detects the voltage sampling differential input signal; the current sampling circuit: detects the current sampling differential input signal.

[0005] Preferably, the voltage sampling circuit includes a differential signal amplification circuit, a full-wave precision rectifier circuit, a terminal filter circuit, a detection protection circuit and an A / D conversion circuit; the differential signal amplification circuit in the voltage sampling circuit amplifies the voltage sampling differential input signal to form a voltage amplification signal; the voltage amplification signal is introduced into the input end of the full-wave precision rectifier circuit, and the sampled sinusoidal signal is rectified and converted into a DC signal; the output end of the full-wave precision rectifier circuit is connected to the interface detection protection circuit and the interface terminal filter circuit in sequence, and then the analog signal is converted into a digital signal through the A / D conversion circuit, and finally input into the signal input end of the microcontroller.

[0006] Preferably, the current sampling circuit includes a differential signal amplification circuit, a full-wave precision rectifier circuit, a terminal filter circuit, a detection protection circuit and an A / D conversion circuit; the differential signal amplification circuit of the current sampling circuit amplifies the current sampling differential input signal to form a current amplification signal; the current amplification signal is introduced into the input end of the full-wave precision rectifier circuit, and the sampled sinusoidal signal is rectified and converted into a DC signal; the output end of the full-wave precision rectifier circuit is connected to the interface detection protection circuit and the interface terminal filter circuit in sequence, and then the analog signal is converted into a digital signal through the A / D conversion circuit and input into the signal input end of the microcontroller.

[0007] Preferably, the terminal filtering circuit: grounds the DC signal output terminal through a filtering capacitor to eliminate the ripple signal after rectification and ensure that the output is a stable DC power; the interface detection protection circuit: grounds the DC signal output terminal through a reverse-connected Zener diode to prevent the output voltage from exceeding the maximum allowable input voltage of the microcontroller through diode voltage stabilization.

[0008] Preferably, it also includes a filter circuit at the output end of the amplifier: the signal at the output end of the power amplifier circuit passes through filter resistor 1 and capacitor 1.

[0009] Preferably, it also includes an isolation filter circuit: the second filter resistor is directly connected between the output end of the sinusoidal signal after D / A conversion and the input end of the circuit, and the second filter capacitor is connected in series between the input ends of the power amplifier circuit.

[0010] Preferably, two ends of the secondary side of the boost transformer circuit are respectively connected to two groups of transformers, the first group of transformers draws out a voltage V_IN1+, and the second group of transformers draws out a voltage, V_IN1, wherein V_IN1 is a negative voltage and V_IN1+ is a positive voltage, and the V_IN1 and V_IN1+ are respectively used as voltage sampling differential input signals and connected to the input end of the voltage sampling circuit; the differential signal amplification circuit in the voltage sampling circuit is a first high-speed dual JFET input operational amplifier, and V_IN1 and V_IN1+ are respectively connected to the positive input end and the reverse input end of the first high-speed dual JFET input operational amplifier.

[0011] Preferably, a current limiting resistor is connected in series at either end of the secondary side of the boost transformer circuit, and two groups of shunt resistors are respectively led out from the two ends of the resistor, the first group of shunt resistors leads to A_IN1, and the second group of shunt resistors leads to A_IN1+, wherein A_IN1 is a negative signal and A_IN1+ is a positive signal, and the A_IN1 and A_IN1+ are used as current sampling differential input signals and connected to the input end of the current sampling circuit; the differential signal amplification circuit in the current sampling circuit is a second high-speed dual JFET input operational amplifier, and A_IN1+ and A_IN1 are respectively connected to the positive input end and the reverse input end of the first high-speed dual JFET input operational amplifier.

[0012] Preferably, a feedback resistor and a feedback capacitor are connected in parallel between the inverting input terminal and the output terminal of the differential signal amplification circuit, and the output signal is fed back to the inverting input terminal through the feedback resistor to form deep negative feedback to ensure that the output voltage of the operational amplifier is in a linear relationship with the input voltage.

[0013] Beneficial effects of the present invention: 1. Accurate and automatic signal acquisition: Through the differential amplifier circuit and full-wave precision rectification circuit, common-mode interference and signal distortion can be effectively eliminated to ensure high-precision automatic acquisition and detection of voltage and current signals. The full-wave rectification design of the diode reduces the voltage drop problem in the traditional rectification circuit, which is particularly suitable for processing weak signals and improves the sensitivity of the test system.

[0014] 2. Signal stability and noise suppression: The multi-stage filter circuit designed in the system, including the interface filter circuit and the terminal filter circuit, effectively eliminates the ripple and high-frequency noise in the rectified signal, ensuring the stability of the output signal and the stable output of the DC current. This has a significant effect on improving the signal quality and output accuracy of the system.

[0015] 3. Safety protection and system reliability: The diode voltage regulator design of the interface detection protection circuit prevents the output voltage from exceeding the allowable voltage range of the microcontroller, effectively preventing overvoltage damage to the system and improving the stability and reliability of the entire test system.

[0016] 4. Constant current output: The design of the constant current feedback circuit ensures the stability of the output current when the load changes, is not affected by external interference, adapts to impedance changes in various physical therapy application scenarios, and provides a more consistent treatment effect.

[0017] 5. Efficient power amplification and boost: The combination of class AB power amplifier circuit and boost transformer ensures that the input signal can achieve a higher voltage output after amplification, which is suitable for testing electrodes with larger impedance and improves the applicability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a relationship block diagram of the electrode impedance testing system of the present invention; Figure 2 This is the main circuit diagram of the electrode impedance testing system of the present invention; Figure 3 It is the circuit schematic diagram of the voltage sampling circuit; Figure 4 It is the circuit schematic diagram of the current sampling circuit.

[0019] Figure 2-4The numbers in the figure are as follows: 1-D / A conversion circuit; 2-isolation filter circuit; 3-power amplifier circuit; 4-life transformer circuit; 5-voltage sampling circuit; 6-current sampling circuit; 7-electrode measurement interface circuit; 8-differential signal amplification circuit; 9-full-wave precision rectifier circuit; 10-detection protection circuit; 11-filter circuit.

[0020] Specific implementation method: The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0021] Embodiment 1: An electrode impedance test system for physical therapy, mainly comprising a microcontroller, a D / A conversion circuit, a DC blocking filter circuit, a class AB power amplifier circuit, a step-up transformer circuit, an electrode test interface circuit, a voltage sampling circuit, a current sampling circuit, a full-wave precision rectifier circuit, an interface filter circuit, an interface detection protection circuit, an A / D conversion circuit, etc. Figure 1 The system is used to accurately collect the voltage and current signals of a pair of electrode sheets, detect the electrode impedance of the electrode sheets, and ensure the stability and reliability of the output signal through differential amplification, full-wave rectification and filtering, while protecting the microcontroller from voltage over-limit damage.

[0022] Microcontroller in the system: As the control center of the system, it outputs square wave signals. D / A conversion circuit: Converts the square wave signal output by the microcontroller into a sinusoidal signal. Power amplifier circuit: Amplifies the power of the sinusoidal signal. Step-up transformer circuit: The primary side is connected to the sinusoidal signal processed by the front end, the secondary side is connected to the electrode sheet for testing, and the secondary side is connected to the output voltage sampling differential input signal and the current sampling differential input signal. Voltage sampling circuit: Detects the voltage sampling differential input signal. Current sampling circuit: Detects the current sampling differential input signal.

[0023] The voltage sampling circuit includes a differential signal amplification circuit, a full-wave precision rectifier circuit, a terminal filter circuit, a detection protection circuit and an A / D conversion circuit. The differential signal amplification circuit in the voltage sampling circuit amplifies the voltage sampling differential input signal to form a voltage amplification signal; the voltage amplification signal is introduced into the input end of the full-wave precision rectifier circuit, and the sampled sinusoidal signal is rectified and converted into a DC signal. After the output end of the full-wave precision rectifier circuit is connected to the interface detection protection circuit and the interface terminal filter circuit in sequence, the analog signal is converted into a digital signal through the A / D conversion circuit, and finally input into the signal input end of the microcontroller.

[0024] The current sampling circuit includes a differential signal amplification circuit, a full-wave precision rectifier circuit, a terminal filter circuit, a detection protection circuit and an A / D conversion circuit. The differential signal amplification circuit of the current sampling circuit amplifies the current sampling differential input signal to form a current amplification signal; the current amplification signal is introduced into the input end of the full-wave precision rectifier circuit, and the sampled sinusoidal signal is rectified and converted into a DC signal; the output end of the full-wave precision rectifier circuit is connected to the interface detection protection circuit and the interface terminal filter circuit in sequence, and then the analog signal is converted into a digital signal through the A / D conversion circuit and input into the signal input end of the microcontroller.

[0025] The boost transformer in this system is used to increase the voltage amplitude of the high sinusoidal signal. The primary side of the transformer is connected to the sinusoidal signal processed by the front end, and the secondary side of the transformer is used to connect the electrode sheet for testing. The secondary side has circuits for voltage sampling and current sampling. Since the signal passing through the voltage or current sampling circuit is still a sinusoidal signal, it cannot be directly supplied to the microcontroller for processing. Here, the precision rectifier circuit composed of the operational amplifier is rectified. The filter circuit is used to eliminate the ripple signal after rectification to ensure that the output is a stable direct current. It also includes a detection protection circuit, which uses diode voltage stabilization to output a voltage value that exceeds the maximum allowable input voltage of the microcontroller.

[0026] Embodiment 2: A circuit example based on the system described in Embodiment 1. The specific circuit principle is as follows: Figure 2 As shown, the microcontroller and the D / A conversion circuit replace the function of the signal generator in the prior art. The voltage detection is used to replace the function of the ammeter in the prior art, and the current detection is used to replace the function of the oscilloscope in the prior art.

[0027] Figure 2 In the present invention, the voltage sampling circuit mainly involves a microcontroller, a D / A conversion circuit, a power amplifier circuit, a voltage detection circuit and a current detection circuit, as well as a step-up transformer circuit, etc.

[0028] 1. Input signal direction: The input signal "sinusoidal signal after D / A conversion" comes from the microcontroller and the D / A conversion circuit. The D / A conversion circuit converts the square wave signal output by the microcontroller into a sine signal. This signal enters the circuit through the R2 resistor current limiting and passes through the R4 resistor and the C2 capacitor.

[0029] Isolation filter circuit: R2 and R4 play the role of current limiting and voltage distribution, C2 is a coupling capacitor, used to filter out the DC component in the input signal and only allow the AC signal to pass. R2 and C2 together form an isolation filter circuit. R2 plays the role of current limiting protection, and the AC passing characteristics of C2 capacitor are used to isolate DC processing. This combination can ensure the stability of the input signal and protect the safety of subsequent circuits.

[0030] 2. Operational Amplifier Circuit: U1 constitutes a constant voltage AB type power amplifier circuit, which is responsible for amplifying the input signal. The input signal enters the positive input terminal of U1 after passing through C2, while the negative input terminal is grounded. In the filter circuit at the amplified output terminal, the signal at the output terminal of U1 passes through resistor R1 and capacitor C1. This path is used for further signal filtering and current limiting.

[0031] 3. Step-up transformer circuit: T1 is a step-up transformer, and the amplified signal enters the primary side (primary coil) of transformer T1. The function of the transformer is to perform signal isolation and voltage conversion. The secondary side (secondary coil) of the transformer is connected to two signal lines, marked as 1A and 1B. These two ports are the output ends of the circuit and serve as the detection ends of the electrode measurement interface circuit to detect the electrode impedance of the electrode sheet.

[0032] It also includes a filter circuit at the output end of the amplifier: the signal at the output end of the power amplifier circuit passes through a filter resistor R1 and a capacitor C1. The functions of C3 and C7 are to isolate the DC, C3 is to isolate the DC component from the power amplifier to the transformer output, and C7 is to isolate the DC component from the resistor R14 to the negative feedback of the power amplifier.

[0033] 4. Voltage detection module: On the signal line of the secondary side of the transformer, the voltage detection module performs voltage sampling through a resistor voltage divider network composed of R3, R5, R9 and R13, and obtains the voltage requirement suitable for the subsequent microcontroller signal input by voltage division. V_IN1 and V_IN1+ are differential input signals for voltage sampling, V_IN1 is a negative voltage, and V_IN1+ is a positive voltage. A_IN1 and A_IN1+ are differential input signals for current sampling. Specifically, two groups of voltage dividers are connected to the two ends of the secondary side of the boost transformer circuit, the first group of voltage dividers is R3 and R5, and the second group of voltage dividers is R9 and R13. The two groups of voltage dividers lead out voltages V_IN1+ and V_IN1, respectively, wherein V_IN1 is a negative voltage and V_IN1+ is a positive voltage. The V_IN1 and V_IN1+ are respectively used as voltage sampling differential input signals to connect the input end of the voltage sampling circuit.

[0034] 5. Current detection module: The current detection circuit mainly samples the current signal through R7, R8, R11, R12, C4 and C6. Specifically, a current limiting resistor R10 is connected in series at either end of the secondary side of the boost transformer circuit, the first group of split resistors is R7 and R8 connected to the rear end of the resistor R10, the second group of split resistors is R11 and R12 connected to the front end of the resistor R10, and the two groups of split resistors lead out A_IN1 and A_IN1+ respectively, where A_IN1 is a negative signal and A_IN1+ is a positive signal, and A_IN1 and A_IN1+ are used as current sampling differential input signals and connected to the input end of the current sampling circuit.

[0035] In the current detection circuit, C4 and C6 are connected in series with each group of voltage-dividing resistors to play a filtering role, ensuring the smoothness and stability of the sampling signal and reducing the interference of high-frequency noise.

[0036] 6.Signal feedback and control: The detected voltage and current signals are transmitted back to the front-end control circuit through a feedback loop to adjust the gain of the amplifier or adjust the amplitude of the input signal.

[0037] The voltage and current detection circuit can provide accurate monitoring data for the system to ensure the stability and reliability of the entire system.

[0038] The circuit amplifies the input sinusoidal signal through the operational amplifier U1 and couples and isolates the signal through the transformer. The signal on the secondary side of the transformer passes through the voltage and current detection module to provide feedback information for monitoring and controlling the operation of the system.

[0039] 7. Voltage sampling circuit and current sampling circuit: Figure 3 The voltage sampling circuit includes a differential signal amplification circuit, a full-wave precision rectification circuit, a terminal filtering circuit, a detection protection circuit and an A / D conversion circuit. Figure 4 The current sampling circuit includes a differential signal amplification circuit, a full-wave precision rectification circuit, a terminal filtering circuit, a detection protection circuit and an A / D conversion circuit. Figure 3 and Figure 4In the figure, U2B is a high-speed dual JFET input operational amplifier, which inputs differential signals V_IN1 (negative signal) and V_IN1+ (positive signal), and the 4 terminals of U2B are used to obtain (V_IN1+) with twice the amplitude. U4B is a high-speed dual JFET input operational amplifier, which inputs differential signals A_IN1 (negative signal) and A_IN1+ (positive signal), and the 4 terminals of U4B are used to obtain (A_IN1+) with twice the amplitude. U2A and U3B form a precision rectifier circuit, and U5B and U3A form a precision rectifier circuit. D3 and D6 are voltage regulator diodes used to prevent the voltage of the input microcontroller from exceeding the limit. C10 and C16 are used for filtering after rectification. U2A, U3B, U5B, and U3A are dual-power supply (+5V, 5V) operational amplifiers.

[0040] Both the voltage sampling circuit and the current sampling circuit include a differential signal amplification circuit, a full-wave precision rectification circuit, a filtering circuit, a detection protection circuit and an A / D conversion circuit. The differential signal amplification circuit in the voltage sampling circuit amplifies V_IN1+ and V_IN1 to form a voltage amplification signal, and the differential signal amplification circuit in the current sampling circuit amplifies A_IN1 and A_IN1+ to form a current amplification signal. Each amplified signal is introduced into the input end of the full-wave precision rectification circuit respectively, and the sampled sinusoidal signal is rectified and converted into a DC signal; after the output end of the full-wave precision rectification circuit is connected to the interface detection protection circuit and the interface filtering circuit in sequence, the interface filtering circuit: eliminates the ripple signal after rectification to ensure that the output is a stable DC power; the interface detection protection circuit: prevents the output voltage from exceeding the maximum allowable input voltage of the microcontroller through diode voltage stabilization; the A / D conversion circuit: converts the processed analog signal into a digital signal and inputs it into the signal input end of the microcontroller.

[0041] The differential signal amplifier circuit in the voltage sampling circuit amplifies V_IN1+ and V_IN1 to form a voltage amplified signal; the voltage amplified signal is introduced into the A / D conversion circuit U2B, the input positive signal V_IN1 is introduced into the positive input terminal of U2B, and the input negative signal V_IN1 is introduced into the reverse input terminal of U2B, and the amplitude of the output signal of U2B is the amplification multiple of the difference between the two. A feedback resistor and a feedback capacitor are connected in parallel between the reverse input terminal and the output terminal of the differential signal amplifier circuit, and the output signal is fed back to the inverting input terminal through the feedback resistor to form a deep negative feedback to ensure that the output voltage of the operational amplifier is in a linear relationship with the input voltage. The differential signal amplifier circuit in the current sampling circuit amplifies A_IN1+ and A_IN1 to form a current amplified signal; the current amplified signal is introduced into the A / D conversion circuit U4B, the input positive signal A_IN1+ is introduced into the positive input terminal of U4B, and the input negative signal A_IN1 is introduced into the reverse input terminal of U4B, and the amplitude of the output signal of U4B is the amplification multiple of the difference between the two. A feedback resistor and a feedback capacitor are connected in parallel between the inverting input and output of the differential signal amplifier circuit, and the output signal is fed back to the inverting input through the feedback resistor to form a deep negative feedback to ensure that the output current of the operational amplifier is in a linear relationship with the input current. The differential signal form is selected for sampling to eliminate common mode interference during the sampling process.

[0042] The voltage sampling circuit is the same as the current sampling circuit full-wave precision rectifier circuit. Figure 4 Taking the full-wave precision rectifier circuit in Figure 1 as an example, the input end of the full-wave precision rectifier circuit rectifies the sampled sinusoidal signal and converts it into a DC signal. Resistors R28 and R29 are connected to the input signal to limit the input current and prevent excessive current from affecting the circuit. After passing through these resistors, the input signal will be sent to two diodes D4 and D5 to process the positive and negative half-cycles of the signal respectively. The operational amplifier U3A provides necessary amplification when the input signal is very small. Since the rectification process involves changes in the signal amplitude, the influence of the diode conduction voltage drop (usually 0.7V) on the signal can be avoided by the operational amplifier. The positive input end of U3A is connected to the ground, and the negative input end receives the input signal and amplifies it by feedback. D4 and D5 are key rectifier components: when the input signal is positive, D4 ​​is turned on, and the signal passes through D4 and is passed to the operational amplifier. When the input signal is negative, D5 is turned on, and the signal is passed to the operational amplifier through D5. In this way, whether the input signal is positive or negative, the corresponding forward voltage can be output through the operational amplifier.

[0043] Feedback circuit and output rectification: R26 and R30 are feedback resistors used to control the gain of the operational amplifier. The feedback circuit ensures that the amplitude of the output signal can better follow the changes of the input signal. The rectified signal is transmitted to the next level processing unit U5B, which is another operational amplifier, through the R30 resistor. After passing through the filter capacitor C14, the signal is more stable.

[0044] The secondary operational amplifier is the second stage op amp, which is mainly used to further amplify the rectified signal. Through the feedback setting of resistors R27 and R35, it is able to adjust the gain and stability of the final output signal. R35 acts as a pull-down resistor to ensure that the signal is not floating when there is no input and references the signal to ground.

[0045] Capacitors C17 and C18 are filter capacitors connected to the power supply line to ensure the smooth power supply of the operational amplifier and remove high-frequency noise in the power supply. The operational amplifiers U3A and U5B are powered by dual power supplies, +5V and 5V respectively. This power supply configuration allows the amplifier to process positive and negative bidirectional input signals, improving the dynamic range of the circuit.

[0046] The circuit uses diodes D4 and D5 to separate and conduct the positive and negative half-cycles, and realizes full-wave rectification through the reverse input amplification and feedback loop of the operational amplifier. During the positive half-cycle, the signal is conducted through D4, and during the negative half-cycle, the signal is conducted through D5. The rectified signal is output by the amplifier to become a full-wave signal with doubled amplitude. Finally, the rectified signal is smoothed by the filter capacitor C14 and output through the secondary amplifier to ensure that the output signal is stable and reliable. C8 and R14 in the circuit respectively form constant current feedback circuits. When the load changes, the current at both ends of the load remains unchanged.

[0047] The key to the design of this full-wave precision rectifier circuit is the precision amplification function of the operational amplifier and the conduction characteristics of the diode, which can effectively avoid the voltage drop problem in traditional diode rectification and can accurately process smaller signals.

[0048] The output end of the full-wave precision rectifier circuit is connected to the interface detection protection circuit and the interface terminal filter circuit in sequence, and then the analog signal is converted into a digital signal through the A / D conversion circuit, and finally input into the signal input end of the microcontroller.

[0049] like Figure 3 and Figure 4 The terminal filter circuit in the circuit connects the DC signal output terminal to ground through a filter capacitor (C10 or C16) to eliminate the ripple signal after rectification and ensure that the output is stable DC. Interface detection protection circuit: connects the DC signal output terminal to ground through a reverse-connected voltage-stabilizing diode (D3 or D6) to prevent the output voltage from exceeding the maximum allowable input voltage of the microcontroller through diode voltage stabilization.

[0050] Embodiment 3: Based on the system described in the above embodiment 2, the specific implementation steps are as follows: 1. Equipment connection and preparation: Connect the electrode sheet to be tested to the electrode test interface, and ensure that the electrode is reliably connected to the electrode test interface circuit of the system. Turn on the system power supply and ensure that the microcontroller, D / A conversion circuit, power amplifier circuit and other components are working properly.

[0051] 2. Generate test signal: The microcontroller generates a square wave signal according to the set frequency, and the square wave signal is converted into a sine wave signal through the D / A conversion circuit. Through D / A conversion, the sine wave signal is used to simulate the actual working environment of the electrode impedance test to ensure that the test signal is accurate and the frequency is stable.

[0052] 3. Signal amplification and boosting: The sinusoidal signal enters the class AB power amplifier circuit, and the power amplifier amplifies the current of the signal to ensure that the signal can drive the electrode and generate a suitable test voltage. Boosting by boosting transformer: The amplified signal passes through the boosting transformer, and the voltage amplitude is increased to the required test voltage to drive the electrode sheet. The amplification and boosting process ensures that the test signal can adapt to the electrode sheets with different impedance values, providing more accurate impedance measurement.

[0053] 4. Voltage and current signal acquisition: The boosted signal passes through the voltage detection module, and the voltage signal passes through the voltage divider circuit (such as R3, R5, R9, R13), amplifies the voltage signal through the differential amplifier circuit, and enters the full-wave precision rectifier circuit for rectification, and finally outputs a stable DC voltage. Current sampling circuit operation: The current signal passes through the current limiting resistor and the current detection module, and the current signal is also differentially amplified and rectified through the full-wave precision rectifier circuit to output a stable DC signal. Through differential amplification and precision rectification, the system can accurately collect voltage and current signals, eliminate common-mode interference and signal distortion, and ensure test accuracy.

[0054] 5. Signal filtering and protection: The collected signals of voltage and current pass through the filtering circuit to eliminate the ripple and noise after rectification, ensuring the smoothness and stability of the signal. The filtered signal passes through the detection and protection circuit, and the voltage regulator diode limits the voltage of the signal to prevent the signal voltage from exceeding the allowable range of the microcontroller and protect the safety of the system. The filtering circuit effectively removes noise, and the detection and protection circuit ensures that the system works safely in a high voltage environment and prolongs the life of the equipment.

[0055] 6. Analog-to-digital conversion: The filtered and protected analog signal is input into the A / D conversion circuit, which converts the collected analog voltage and current signals into digital signals. The microcontroller receives the digital signal after A / D conversion, performs impedance calculation, and obtains the impedance value of the electrode. Analog-to-digital conversion ensures that the collected analog signal can be converted into a digital signal. The microcontroller obtains the electrode impedance through calculation, and the result is accurate.

[0056] 7. Result display and analysis: The microcontroller calculates the impedance value of the electrode based on the collected voltage and current signals and outputs the data to the display module or storage device. Users can judge the performance and quality of the electrode based on the impedance value displayed by the system. The system can display the measurement results in real time and accurately, providing a basis for electrode performance analysis and simplifying the electrode testing process.

[0057] 8. System shutdown and reset: After the test is completed, turn off the system power supply, disconnect the electrode sheet, and ensure the safety of the equipment. The equipment can be reset as needed to prepare for the next test. The system is easy to operate, and the shutdown and reset process is safe and reliable, which is convenient for repeated use.

[0058] During use, the system can quickly and accurately complete electrode impedance testing through precise signal generation, amplification, acquisition, rectification, filtering and protection, which simplifies the testing process and improves test accuracy and system reliability.

[0059] The above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modification, equivalent substitution, improvement, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention.

Claims

1. An electrode impedance testing system for physical therapy, comprising a microcontroller, a D / A conversion circuit, a power amplifier circuit, a voltage detection circuit and a current detection circuit, and a step-up transformer circuit, characterized in that: Microcontroller: acts as the control center of the system and outputs square wave signals; D / A conversion circuit: converts the square wave signal output by the microcontroller into a sinusoidal signal; power amplifier circuit: performs power amplification on the sinusoidal signal; step-up transformer circuit: the primary side is connected to the sinusoidal signal processed by the front end, the secondary side is connected to the electrode sheet for testing, and the secondary side is connected to the output voltage sampling differential input signal and the current sampling differential input signal; voltage sampling circuit: detects the voltage sampling differential input signal; current sampling circuit: detects the current sampling differential input signal.

2. The electrode impedance testing system for physical therapy according to claim 1, characterized in that: The voltage sampling circuit includes a differential signal amplification circuit, a full-wave precision rectification circuit, a terminal filtering circuit, a detection protection circuit and an A / D conversion circuit; the differential signal amplification circuit in the voltage sampling circuit amplifies the current sampling differential input signal to form a voltage amplification signal; the voltage amplification signal is introduced into the input end of the full-wave precision rectification circuit, and the sampled sinusoidal signal is rectified and converted into a DC signal; the output end of the full-wave precision rectification circuit is connected to the interface detection protection circuit and the interface terminal filtering circuit in sequence, and then the analog signal is converted into a digital signal through the A / D conversion circuit, and finally input into the signal input end of the microcontroller.

3. The electrode impedance testing system for physical therapy according to claim 1, characterized in that: The current sampling circuit includes a differential signal amplification circuit, a full-wave precision rectifier circuit, a terminal filter circuit, a detection protection circuit and an A / D conversion circuit; the differential signal amplification circuit of the current sampling circuit amplifies the current sampling differential input signal to form a current amplification signal; the current amplification signal is introduced into the input end of the full-wave precision rectifier circuit, and the sampled sinusoidal signal is rectified and converted into a DC signal; the output end of the full-wave precision rectifier circuit is connected to the interface detection protection circuit and the interface terminal filter circuit in sequence, and then the analog signal is converted into a digital signal through the A / D conversion circuit and input into the signal input end of the microcontroller.

4. The electrode impedance testing system for physical therapy according to claim 2 or 3, characterized in that: The terminal filtering circuit: the DC signal output end is grounded through a filtering capacitor to eliminate the ripple signal after rectification and ensure that the output is a stable DC power; the interface detection protection circuit: the DC signal output end is grounded through a reverse-connected voltage-stabilizing diode, and the voltage is stabilized by the diode to prevent the output voltage from exceeding the maximum allowable input voltage value of the microcontroller.

5. The electrode impedance testing system for physical therapy according to claim 1, characterized in that: It also includes a filter circuit at the output end of the amplifier: the signal at the output end of the power amplifier circuit passes through a filter resistor 1 (R1) and a capacitor 1 (C1).

6. The electrode impedance testing system for physical therapy according to claim 1, characterized in that: It also includes an isolation filter circuit: a second filter resistor (R2) is directly connected between the output end of the sinusoidal signal after D / A conversion and the input end of the circuit, and a second filter capacitor (C2) is connected in series between the input ends of the power amplifier circuit.

7. The electrode impedance testing system for physical therapy according to claim 2, characterized in that: Two ends of the secondary side of the boost transformer circuit are respectively connected to two groups of transformer resistors, the first group of transformer resistors draw out a voltage V_IN1+, and the second group of transformer resistors draw out a voltage, V_IN1, wherein V_IN1 is a negative voltage and V_IN1+ is a positive voltage, and the V_IN1 and V_IN1+ are respectively used as voltage sampling differential input signals and connected to the input end of the voltage sampling circuit; the differential signal amplification circuit in the voltage sampling circuit is a first high-speed dual JFET input operational amplifier (U2B), and V_IN1- and V_IN1+ are respectively connected to the positive input end and the reverse input end of the first high-speed dual JFET input operational amplifier (U2B).

8. The electrode impedance testing system for physical therapy according to claim 3, characterized in that: A current limiting resistor (R10) is connected in series at either end of the secondary side of the step-up transformer circuit, and two groups of transformer resistors are respectively led out from both ends of the resistor (R10), the first group of transformer resistors leads out A_IN1, and the second group of transformer resistors leads out A_IN1+, wherein A_IN1 is a negative signal and A_IN1+ is a positive signal, and the A_IN1 and A_IN1+ are used as current sampling differential input signals and connected to the input end of the current sampling circuit; the differential signal amplification circuit in the current sampling circuit is a second high-speed dual JFET input operational amplifier (U4B), and A_IN1+ and A_IN1- are respectively connected to the positive input end and the reverse input end of the first high-speed dual JFET input operational amplifier (U2B).

9. The electrode impedance testing system for physical therapy according to claim 7 or 8, characterized in that: A feedback resistor and a feedback capacitor are connected in parallel between the inverting input terminal and the output terminal of the differential signal amplification circuit, and the output signal is fed back to the inverting input terminal through the feedback resistor to form deep negative feedback to ensure that the output voltage of the operational amplifier is in a linear relationship with the input voltage.

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