Safety protection circuit and method for external counterpulsation

Abstract

The invention relates to the technical field of medical instrument circuits, and discloses an external counterpulsation safety protection circuit and method, one end of a TVS1 tube is connected with a pressure sensor signal output end of external counterpulsation equipment, and the other end of the TVS1 tube is grounded; the double operational amplifiers SGM8608 comprise a built-in U1A and a built-in U1B; one end of the resistor R23 is connected with the signal output end of the TVS1, the other end of the resistor R23 is connected with the in-phase input end of the U1A, and the resistor R23 is used for converting a current signal output by the pressure sensor into an initial voltage signal. According to the safety protection circuit and method for external counterpulsation, through the cascade design of TVS1 tube front transient high-voltage clamping, U1A low-noise amplification and U1B filtering and in cooperation with auxiliary circuits such as power decoupling filtering and a lag compensation network, signal distortion caused by independent arrangement of protection and amplification elements is reduced, the precision of pressure collection in a high-pressure scene is guaranteed, and the safety of external counterpulsation is improved. And meanwhile, stable inflation and deflation can be realized without depending on a large air storage tank, so that the defect that miniaturization is difficult due to insufficient protection in the prior art is overcome.

Description

Technical Field

[0001] This invention relates to the field of medical device circuit technology, specifically to a safety protection circuit and method for external counterpulsation. Background Technology

[0002] External counterpulsation with a balloon is a common device for treating various ischemic diseases. It works by inflating the balloon from the distal to the proximal end of the body during diastole, compressing blood and forcing it back into the aorta, thereby increasing blood flow to vital organs such as the heart and brain. During systole, the balloon is rapidly deflated, reducing external resistance and lessening the burden on the heart.

[0003] Currently available external counterpulsation (ECP) devices generally use large gas tanks with low-pressure compressors. Furthermore, to only monitor and protect the gas tank, the cuff cavity, which directly contacts the patient, only undergoes open-loop inflation and deflation. This means that even if the inflation valve malfunctions, the pressure from the gas tank will be applied directly to the cuff. Because this pressure is relatively low, it doesn't pose a safety risk to the cuff or the patient. Therefore, manufacturers typically only provide overpressure protection for the cylinder. However, this approach, which only monitors and protects the gas tank and uses only an open-loop inflation / deflation mode for the cuff cavity, lacks a targeted pressure monitoring and protection mechanism. Moreover, due to the simplistic protection logic, miniaturizing the device requires reducing the gas tank size and increasing its pressure. Existing protection circuits cannot handle the safety risks under high pressure. If components such as the inflation valve malfunction, the high-pressure gas in the gas tank will leak directly into the cuff, easily causing the cuff to rupture and injuring the patient, leading to a safety accident. This single protection mode also hinders the miniaturization of ECP devices. Summary of the Invention

[0004] (a) Technical problems to be solved:

[0005] To address the shortcomings of existing technologies, this invention provides a safety protection circuit and method for external counterpulsation, which solves the problems mentioned in the background art where external counterpulsation devices only provide overpressure protection for the gas tank, lack a targeted pressure monitoring and protection mechanism for the airbag cavity that directly contacts the patient, and cannot cope with the safety risks of high-pressure scenarios required for device miniaturization, and are prone to airbag rupture and injury to the patient due to component failure.

[0006] (II) Technical Solution:

[0007] To achieve the above objectives, the present invention provides the following technical solution: a safety protection circuit and method for external counterpulsation, comprising:

[0008] TVS1 tube, one end is connected to the pressure sensor signal output terminal of the external counterpulsation device, and the other end is grounded;

[0009] Dual op-amps SGM8608, including built-in U1A and U1B;

[0010] Resistor R23 is connected at one end to the signal output terminal of the TVS1 transistor and at the other end to the non-inverting input terminal of U1A, and is used to convert the current signal output by the pressure sensor into an initial voltage signal.

[0011] Resistor R27 and RC filter network;

[0012] The inverting input terminal of U1A is connected to its own output terminal through the resistor R27 to form a non-inverting amplifier circuit, which amplifies the initial voltage signal. The output terminal of U1A is connected to the input terminal of U1B.

[0013] The U1B forms a second-order active low-pass filter through the RC filter network connected in parallel at the feedback terminal, and its output terminal is connected to the ADC sampling module.

[0014] By cascading the TVS1 tube for pre-protection, the U1A low-noise amplifier, and the U1B filter, transient high voltage can be quickly clamped to prevent damage to subsequent circuits. This also reduces signal distortion caused by the independent setting of protection and amplification components, ensuring the accuracy and safety of the external counterpulsation device in collecting gas pressure, and supporting the miniaturization design of the device.

[0015] Preferably, it further includes:

[0016] +5V power supply;

[0017] Resistor R21, one end connected to +5V power supply;

[0018] Resistor R22 has one end connected to resistor R21 and the other end grounded, forming a series voltage divider circuit with resistor R21;

[0019] The series connection of resistors R21 and R22 is connected to the power supply circuit of the pressure sensor, providing a stable reference voltage for the pressure sensor. This enables the output signal of the pressure sensor to be matched with the reference of the current-to-voltage conversion of resistor R23, ensuring the accuracy of signal acquisition.

[0020] Preferably, it further includes:

[0021] +12V power supply;

[0022] Capacitors C29 and C28 are connected in parallel and positioned between the +12V power supply and ground to form a power supply decoupling filter circuit, which suppresses power supply noise interference to the non-inverting amplifier circuit.

[0023] Capacitor C30, with one end connected to the output terminal of U1A and the other end grounded, is used to filter out high-frequency noise amplified by U1A and optimize the signal quality input to U1B.

[0024] Capacitor C31 is connected in series with resistor R26, and then in parallel with the feedback loop of U1B. Together with the RC filter network, they form a third-order active low-pass filter to further compress the cutoff frequency.

[0025] Preferably, it further includes:

[0026] Test point TP2 is set between the TVS1 tube and the resistor R23 to detect the original current signal after transient protection.

[0027] Test point TP4 is set at the connection node between the +12V power supply and the capacitor C29 to monitor the stability of the power supply.

[0028] Interface J16 is the standard interface for the signal input of the pressure sensor. Pin 1 is connected to the signal input terminal of the TVS1 tube, and pin 2 is grounded, enabling quick plugging and unplugging of the sensor and the circuit and foolproof connection.

[0029] Resistors R24 and R25 are connected in series between the output terminal of U1B and the signal input interface ADCIN-1 of the ADC sampling module to form current limiting protection and prevent the ADC sampling module from being damaged by overcurrent.

[0030] Preferably, it further includes:

[0031] Test point XHB-2A is set on the signal transmission path between the TVS1 tube and the resistor R23. It is used to detect the original signal output by the pressure sensor after transient protection in real time, which facilitates circuit debugging and fault diagnosis and ensures the reliability of signal acquisition and transmission.

[0032] Preferably, it further includes:

[0033] Capacitor C32 is connected at one end to the inverting input terminal of U1A and at the other end to the output terminal of U1A. It is connected in parallel with resistor R27 to form a hysteresis compensation network, which suppresses the self-excited oscillation of the non-inverting amplifier circuit and ensures the stability of low-noise amplification.

[0034] Preferably, the resistor R27 and the capacitor C32 form a hysteresis compensation network to prevent the circuit from oscillating.

[0035] Preferably, the non-inverting input terminal of the U1A is grounded through the TVS1 transistor to suppress voltage surges.

[0036] Preferably, the -3dB cutoff frequency of the U1B is set to 50Hz to filter out high-frequency interference in the pressure signal.

[0037] A safety protection method for external counterpulsation includes the following steps:

[0038] a. The counterpulsation control host is activated, which drives the compressor assembly to generate compressed gas. After being cooled by the gas storage tank assembly, the compressed gas is stored in the gas storage tank. The gas sensor monitors the pressure of the gas storage tank in real time. At the same time, the physiological signal acquisition module is triggered to collect human electrocardiogram, blood oxygen, blood pressure and other indicators to provide a basis for the counterpulsation rhythm. During this process, the MCU initializes the four safety protection circuits. Through the threshold setting circuit, appropriate pressure protection values ​​are set for the gas storage tank, calf, thigh and buttock airbags respectively. The +5V power supply provides a stable reference voltage for the pressure sensor through the voltage divider of resistor R21 and resistor R22. The +12V power supply ensures stable power supply through the decoupling filter circuit composed of capacitor C28 and capacitor C29.

[0039] b. The pressure sensor collects the pressure data of the corresponding gas container in real time and outputs a 4-20mA current signal. One end of the TVS1 tube is connected to the signal output terminal of the pressure sensor and the other end is grounded to quickly clamp transient high voltage and avoid damage to the subsequent circuit. The test point TP2 detects the original current signal after transient protection.

[0040] c. The protected current signal is converted into an initial voltage signal of 0.04 to 0.2V through the resistor R23, and input to the non-inverting amplifier circuit to amplify the signal by 10 times to 0.4V to 2V. The signal is then passed to the second-order active low-pass filter to filter out high-frequency noise. The capacitor C30 further optimizes the input signal quality. Finally, the optimized signal is transmitted to the ADC sampling module after being current-limited by the resistors R24 and R25.

[0041] d. The ADC sampling module converts the analog signal into a digital signal and transmits it to the MCU. The MCU performs pressure monitoring and threshold comparison at the software level. At the same time, the optimized voltage signal is synchronously input into the comparison circuit and compared with the reference voltage of the threshold setting circuit in real time at the hardware level. If the pressure exceeds the set threshold, the comparator outputs a high-level signal.

[0042] e. The three-input OR logic gates respectively receive the hardware overvoltage signal from the comparator, the software overvoltage signal from the MCU, and the manual trigger signal from the emergency stop switch. When any signal is high, a drive command is sent to the valve control circuit. When the emergency stop switch is pressed, it directly outputs a high level and triggers all vent valves to open synchronously. The MCU monitors the status of the emergency stop switch in real time.

[0043] f. After receiving the instruction from the OR logic gate, the valve control circuit drives the vent valve to open quickly, releasing the overpressure gas in the corresponding gas container until the pressure returns to a safe range. Throughout the process, the counterpulsation control host continuously adjusts the inflation and deflation rhythm of the inflation and deflation components based on the feedback from the physiological signal acquisition module to ensure the normal progress of counterpulsation therapy. At the same time, all protection circuits are on duty throughout the process.

[0044] (III) Beneficial Effects:

[0045] The safety protection circuit and method for external counterpulsation provided by this invention have the following beneficial effects:

[0046] 1. This safety protection circuit and method for external counterpulsation, through the cascaded design of TVS1 tube pre-transient high voltage clamping, U1A low noise amplification and U1B filtering, combined with auxiliary circuits such as power supply decoupling filtering and hysteresis compensation network, reduces signal distortion caused by independent setting of protection and amplification components, ensures the accuracy of pressure acquisition in high-pressure scenarios, and achieves stable gas filling and discharging without relying on large gas storage tanks, thus solving the defect of existing technology that is difficult to miniaturize due to insufficient protection.

[0047] 2. This safety protection circuit and method for external counterpulsation, by setting up four independent pressure monitoring and protection circuits for the air tank, calf airbag, thigh airbag and buttock airbag, combined with a dual overpressure protection mechanism of software and hardware, solves the defects of existing technology that only protects the air tank from overpressure and lacks targeted protection for the airbag cavity. Even if the pressure of the air tank is increased due to the miniaturization design, it can respond quickly in scenarios such as inflation valve failure, avoiding high pressure from being directly released into the airbag and causing rupture and injury, thus greatly improving the safety of equipment use. Attached Figure Description

[0048] Figure 1 This is a circuit connection diagram for the present invention;

[0049] Figure 2 This is a schematic diagram of the pneumatic external counterpulsator of the present invention;

[0050] Figure 3 This is a block diagram illustrating the core principle of the circuit of this invention;

[0051] Figure 4 This is a distributed block diagram of the safety protection circuit corresponding to the independent gas capacitor of the present invention. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] Example 1

[0054] refer to Figures 1 to 4 A safety protection circuit and method for external counterpulsation according to a preferred embodiment of the present invention will be described in detail below, including:

[0055] The TVS1 tube connects to the pressure sensor signal output terminal of the external counterpulsation device at one end and is grounded at the other end. This allows the TVS1 tube to quickly conduct when a transient high voltage occurs in the pressure sensor output signal, clamping the high voltage within a safe range and releasing excess energy directly through the ground terminal, thus preventing the high voltage signal from directly entering the subsequent circuit and causing component breakdown or damage.

[0056] The dual operational amplifier SGM8608, including built-in U1A and U1B, ensures the consistency of the operating parameters of U1A and U1B, thereby improving the stability and reliability of the circuit operation, while reducing the number of components in the circuit, thus adapting to miniaturized external counterpulsation devices.

[0057] Resistor R23 is connected at one end to the signal output terminal of TVS1 and at the other end to the non-inverting input terminal of U1A. It is used to convert the current signal output by the pressure sensor into an initial voltage signal.

[0058] Resistor R27 and RC filter network work together to amplify the signal and filter out noise, respectively, thus ensuring the quality of signal processing.

[0059] The inverting input of U1A is connected to its output via resistor R27 to form a non-inverting amplifier circuit, amplifying the initial voltage signal. The output of U1A is connected to the input of U1B. Utilizing the high input impedance and low output impedance of the non-inverting amplifier circuit, the load on the preceding signal source is reduced, while the amplified signal is stabilized. The direct connection between U1A and U1B shortens the signal transmission path, reducing signal loss and interference during transmission, ensuring the amplified signal is completely input to the filtering stage.

[0060] U1B forms a second-order active low-pass filter through an RC filter network connected in parallel at the feedback end. Its output is connected to the ADC sampling module. Compared with the first-order filter, the second-order active low-pass filter has a steeper amplitude-frequency characteristic, which can more effectively filter out high-frequency interference signals. At the same time, the active filter does not require an additional excitation signal and can directly filter the input signal to output a stable low-frequency pressure signal, providing a high-quality input signal for the ADC sampling module.

[0061] By using the cascaded combination of TVS1 tube pre-protection, U1A low-noise amplification and U1B filtering, transient high voltage can be quickly clamped to avoid damage to subsequent circuits, and signal distortion caused by independent setting of protection and amplification components can be reduced, ensuring the accuracy and safety of the external counterpulsation device in collecting gas pressure, and supporting the miniaturization design of the device.

[0062] Also includes:

[0063] The +5V power supply provides a suitable power supply voltage for the pressure sensor, ensuring that the sensor can stably output a standard current signal and provide stable power support for the entire pressure acquisition system.

[0064] Resistor R21 is connected to a +5V power supply at one end. Its resistance value can be precisely calculated and, together with R22, outputs the reference voltage required by the pressure sensor. It also has a current limiting function, which can prevent excessive current from damaging the power supply or pressure sensor due to a short circuit.

[0065] Resistor R22 is connected to resistor R21 at one end and grounded at the other end, forming a series voltage divider circuit with resistor R21. The series voltage divider circuit has a simple structure and high stability, and can accurately divide the +5V power supply voltage into the reference voltage required by the sensor. The grounding terminal ensures the stability of the voltage divider reference and avoids distortion of the sensor output signal due to reference voltage drift.

[0066] The series connection of resistors R21 and R22 is connected to the power supply circuit of the pressure sensor, providing a stable reference voltage for the pressure sensor. This enables the pressure sensor output signal to be matched with the reference of the current-to-voltage conversion of resistor R23, ensuring the accuracy of signal acquisition.

[0067] Also includes:

[0068] The +12V power supply provides a suitable operating voltage for subsequent circuit components such as the dual op-amp SGM8608.

[0069] Capacitors C29 and C28, connected in parallel between the +12V power supply and ground, form a power supply decoupling filter circuit to suppress power supply noise interference with the non-inverting amplifier circuit. Capacitors C29 and C28 filter out power supply noise at different frequencies; the larger capacitor C28 primarily filters low-frequency noise, while the smaller capacitor C29 primarily filters high-frequency noise. Their parallel structure enables noise suppression over a wide frequency range, while the ground terminal provides a release path, ensuring a clean +12V power supply output voltage and preventing power supply noise from interfering with the non-inverting amplifier circuit through the power supply circuit, thus guaranteeing the stability of signal amplification.

[0070] Capacitor C30, with one end connected to the output of U1A and the other end grounded, is used to filter out high-frequency noise after amplification by U1A and optimize the signal quality input to U1B. Specifically, capacitor C30 provides a grounded release path for high-frequency noise, thereby filtering out high-frequency interference mixed in the amplified signal of U1A, preventing this noise from entering the filtering stage of U1B, reducing the burden on subsequent filtering circuits, and optimizing the signal waveform input to U1B, making the filtered signal closer to the real pressure signal.

[0071] Capacitor C31 is connected in series with resistor R26, and then in parallel with the feedback loop of U1B. Together with the RC filter network, they form a third-order active low-pass filter. Compared with the second-order filter, the third-order filter has a steeper attenuation characteristic, which can more thoroughly filter out high-frequency signals that exceed the cutoff frequency, further compress the cutoff frequency, and make the low-frequency characteristics of the output signal more stable.

[0072] The non-inverting input of U1A is grounded through a TVS1 transistor to suppress voltage surges. This connection method allows the TVS1 transistor to be directly connected in parallel between the non-inverting input of U1A and ground. When a voltage surge occurs at the input, the TVS1 transistor quickly turns on, clamping the surge voltage to a safe value. This prevents the surge voltage from directly entering the U1A and damaging the operational amplifier, while also protecting subsequent precision components such as the ADC sampling module.

[0073] The -3dB cutoff frequency of U1 B is set to 50Hz to filter out high-frequency interference in the pressure signal. The pneumatic pressure changes in external counterpulsation devices are low-frequency signals, typically below 50Hz. Setting the cutoff frequency to 50Hz accurately matches the frequency range of the pressure signal, preserving the effective pressure signal while completely filtering out high-frequency interference signals above 50Hz. This ensures that the signal output to the ADC sampling module contains only the true pressure change information, improving the accuracy of pressure monitoring.

[0074] The following is the complete working process and working principle of the above embodiments:

[0075] After the counterpulsation control host is started, the compressor component is driven to generate compressed gas, which is then cooled by the gas storage tank component and stored in the gas storage tank. The gas sensor monitors the pressure of the gas storage tank in real time, and the physiological signal acquisition module simultaneously collects human electrocardiogram, blood oxygen, blood pressure and other indicators to provide a basis for the counterpulsation rhythm.

[0076] Simultaneously, the MCU initializes the four safety protection circuits. Through a threshold setting circuit based on the DAC7311 IDCKR chip, appropriate pressure protection values ​​are set for the air tank, calf, thigh, and buttock airbags respectively (the DAC circuit can output a threshold voltage of 0-2.5V; the higher the voltage, the higher the gas pressure that triggers overpressure protection). The +5V power supply provides a stable reference voltage to the pressure sensor through a voltage divider between resistors R21 and R22. The +12V power supply ensures stable power supply through a decoupling filter circuit composed of parallel capacitors C28 (10uF / 50V) and C29 (100nF). The pressure sensor collects the pressure data of the corresponding air tank in real time and outputs a 4-20mA current signal. One end of the TVS1 transistor (model BV05C-MS optional) is connected to the sensor signal output terminal, and the other end is grounded, quickly clamping transient high voltage to prevent damage to subsequent circuits. The protected current signal is converted into an initial voltage signal of 0.04-0.2V through resistor R23 (10R), and input to a non-inverting amplifier circuit composed of U1A built into the dual operational amplifier SGM8608. This circuit forms feedback by connecting to its own output terminal through resistor R27 (49.9k), amplifying the initial voltage signal by 10 times to 0.4V-2V. After the amplified signal is filtered by capacitor C30 (470nF) to remove high-frequency noise, it is input to a second-order active low-pass filter (-3dB cutoff frequency 50Hz) composed of U1B and an RC filter network. Capacitor C31 and resistor R26 are connected in series and then in parallel in the feedback loop of U1B, forming a third-order active low-pass filter to further compress the cutoff frequency. The optimized signal is then transmitted to a 24-bit ADC sampling module (model ADS1256 optional, communicating with the MCU via SPI). The ADC sampling module converts analog signals into digital signals and transmits them to the MCU. The MCU performs software-level pressure monitoring and threshold comparison. Simultaneously, the optimized voltage signal is synchronously input to the comparator circuit for real-time hardware-level comparison with the reference voltage of the threshold setting circuit. If the pressure exceeds the set threshold, the comparator outputs a high-level signal. A three-input OR logic gate (model optional CD4075BM / TR) receives the hardware overvoltage signal from the comparator, the software overvoltage signal from the MCU, and the manual trigger signal from the emergency stop switch, respectively. When any of these signals is high, a drive command is sent to the valve control circuit. When the emergency stop switch is pressed, it directly outputs a high level and triggers all normally open vent valves (model optional VX240AA) to open synchronously. The MCU monitors the status of the emergency stop switch in real time. After receiving the command, the valve control circuit drives the vent valve to open rapidly, releasing the overpressure gas in the corresponding gas container until the pressure returns to a safe range. Throughout the process, the counterpulsation control host continuously adjusts the inflation and deflation rhythm of the inflation and deflation components based on feedback from the physiological signal acquisition module to ensure the normal operation of counterpulsation therapy. All protection circuits are on duty throughout the process.

[0077] Example 2

[0078] refer to Figure 1 It also includes:

[0079] Test point TP2 is set between TVS1 and resistor R23, allowing staff to directly measure the signal at this point using instruments such as oscilloscopes to determine whether the transient protection function of TVS1 is normal and whether the original signal output by the pressure sensor meets the standard range of 4-20mA. It is used to detect the original current signal after transient protection.

[0080] Test point TP4 is set at the connection node between the +12V power supply and capacitor C29. The output voltage of the +12V power supply can be measured in real time through this test point to monitor the stability of the power supply.

[0081] Interface J16 is the standard interface for pressure sensor signal input. Pin 1 is connected to the signal input terminal of TVS1 tube, and pin 2 is grounded, enabling quick plugging and unplugging of the sensor and circuit and foolproof connection. This improves the convenience of sensor installation and replacement while avoiding damage to the sensor or circuit due to wiring errors.

[0082] Resistors R24 and R25 are connected in series between the output terminal of U1B and the signal input interface ADCIN-1 of the ADC sampling module to form a current limiting protection. This can limit the current transmitted to the ADC sampling module within a safe range. Even if a short circuit or abnormality occurs in the subsequent circuit, it can effectively block excessive current from flowing into the ADC sampling module and prevent the ADC sampling module from being damaged by overcurrent.

[0083] Also includes:

[0084] Test point XHB-2A, located on the signal transmission path between TVS1 and resistor R23, is used to monitor the raw signal output by the pressure sensor after transient protection in real time. This facilitates circuit debugging and troubleshooting, ensuring the reliability of signal acquisition and transmission. Test point XHB-2A complements TP2, allowing monitoring of the front-end signal transmission status from different angles. During circuit debugging, operators can verify the consistency of signal transmission by comparing the signals from the two test points. If pressure acquisition anomalies occur during equipment operation, this test point can quickly determine whether the fault lies in the signal transmission path after TVS1 and before R23, shortening troubleshooting time and ensuring the continuity and reliability of signal acquisition and transmission.

[0085] Also includes:

[0086] Capacitor C32 is connected at one end to the inverting input terminal of U1A and at the other end to the output terminal of U1A. It is connected in parallel with resistor R27 to form a hysteresis compensation network, which suppresses the self-excited oscillation of the non-inverting amplifier circuit and ensures the stability of low-noise amplification.

[0087] Resistor R27 and capacitor C32 form a hysteresis compensation network to prevent self-oscillation in the circuit. Specifically, the capacitive reactance characteristic of the capacitor is used to adjust the phase of the feedback signal, suppressing self-oscillation that may occur in the circuit under high-frequency operation, ensuring the stability of low-noise amplification in the non-inverting amplifier circuit, and thus ensuring the integrity and accuracy of the current signal output by the pressure sensor after conversion by resistor R23, amplification by U1A, and subsequent filtering and sampling.

[0088] The following is the complete working process and working principle of the above embodiments:

[0089] The 4-20mA current signal output by the pressure sensor is clamped by the TVS1 tube to prevent transient high voltage. The original signal after protection can be detected through test points TP2 and XHB-2A, facilitating debugging and troubleshooting. The signal is converted into an initial voltage signal of 0.04-0.2V by resistor R23 (10R) and input to the non-inverting amplifier circuit composed of U1A. This circuit uses resistor R27 and capacitor C32 in parallel to form a hysteresis compensation network to suppress self-excited oscillation, amplifying the signal by 10 times to 0.4V-2V. After the amplified signal is filtered by capacitor C30 to remove high-frequency noise, it is input to the second-order active low-pass filter composed of U1B. Capacitor C31 and resistor R26 are connected in series and then in parallel in the feedback loop of U1B, forming a third-order active low-pass filter to further compress the cutoff frequency. The optimized signal is protected by current limiting by resistors R24 and R25 (both 4.99kΩ) and then transmitted to the ADC sampling module through interface J16. Test point TP4 can monitor the stability of the +12V power supply. The ADC sampling module converts analog signals into digital signals and transmits them to the MCU for software-level threshold comparison. Simultaneously, the voltage signal is synchronously input to the comparison circuit for hardware-level comparison. If the pressure exceeds the threshold, the comparator outputs a high-level signal. The three-input OR logic gate receives the hardware overpressure signal, the MCU software overpressure signal, and the emergency stop switch trigger signal. When any of these signals is high, the valve control circuit opens the normally open vent valve to release pressure. When the emergency stop switch is pressed, it directly outputs a high level to trigger all vent valves to open synchronously. The MCU monitors the status in real time, and the counterpulsation control host adjusts the inflation and deflation rhythm based on physiological signal feedback to ensure normal treatment.

[0090] Example 3

[0091] refer to Figures 1 to 4 A safety protection method for external counterpulsation includes the following steps:

[0092] a. Start the counterpulsation control host to drive the compressor component to generate compressed gas. After being cooled by the gas tank component, the compressed gas is stored in the gas tank. The gas sensor monitors the pressure of the gas tank in real time. At the same time, the physiological signal acquisition module is triggered to collect human electrocardiogram, blood oxygen, blood pressure and other indicators to provide a basis for the counterpulsation rhythm. During this process, the MCU initializes the four safety protection circuits. Through the threshold setting circuit, appropriate pressure protection values ​​are set for the gas tank, calf, thigh and buttock airbags respectively. The +5V power supply provides a stable reference voltage for the pressure sensor through the voltage divider of resistors R21 and R22. The +12V power supply ensures stable power supply through the decoupling filter circuit composed of capacitors C28 and C29.

[0093] b. The pressure sensor collects the pressure data of the corresponding gas container in real time and outputs a 4-20mA current signal. One end of the TVS1 tube is connected to the signal output terminal of the pressure sensor and the other end is grounded to quickly clamp transient high voltage and avoid damage to the subsequent circuit. The test point TP2 detects the original current signal after transient protection.

[0094] c. The protected current signal is converted into an initial voltage signal of 0.04 to 0.2V through resistor R23, and input to the non-inverting amplifier circuit to amplify the signal by 10 times to 0.4V to 2V. Then the signal is passed to a second-order active low-pass filter to filter out high-frequency noise. Capacitor C30 further optimizes the input signal quality. Finally, the optimized signal is transmitted to the ADC sampling module after being protected by current limiting by resistors R24 and R25.

[0095] d. The ADC sampling module converts the analog signal into a digital signal and transmits it to the MCU. The MCU performs pressure monitoring and threshold comparison at the software level. At the same time, the optimized voltage signal is synchronously input to the comparison circuit and compared with the reference voltage of the threshold setting circuit in real time at the hardware level. If the pressure exceeds the set threshold, the comparator outputs a high-level signal.

[0096] e. The three-input OR logic gate receives the hardware overvoltage signal from the comparator, the software overvoltage signal from the MCU, and the manual trigger signal from the emergency stop switch, respectively. When any signal is high, a drive command is sent to the valve control circuit. When the emergency stop switch is pressed, it directly outputs a high level and triggers all vent valves to open synchronously. The MCU monitors the status of the emergency stop switch in real time.

[0097] f. After receiving the instruction from the logic gate, the valve control circuit drives the vent valve to open quickly, releasing the overpressure gas in the corresponding gas container until the pressure returns to a safe range. Throughout the process, the counterpulsation control host continuously adjusts the inflation and deflation rhythm of the inflation and deflation components based on the feedback from the physiological signal acquisition module to ensure the normal progress of counterpulsation therapy. At the same time, all protection circuits are on duty throughout the process.

[0098] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A safety protection circuit for external counterpulsation, characterized in that, include: TVS1 tube, one end is connected to the pressure sensor signal output terminal of the external counterpulsation device, and the other end is grounded; Dual op-amps SGM8608, including built-in U1A and U1B; Resistor R23 is connected at one end to the signal output terminal of the TVS1 transistor and at the other end to the non-inverting input terminal of U1A, and is used to convert the current signal output by the pressure sensor into an initial voltage signal. Resistor R27 and RC filter network; The inverting input terminal of U1A is connected to its own output terminal through the resistor R27 to form a non-inverting amplifier circuit, which amplifies the initial voltage signal. The output terminal of U1A is connected to the input terminal of U1B. The U1 B forms a second-order active low-pass filter through the RC filter network connected in parallel at the feedback terminal, and its output terminal is connected to the ADC sampling module. By cascading the TVS1 tube for pre-protection, the U1A low-noise amplifier, and the U1B filter, transient high voltage can be quickly clamped to prevent damage to subsequent circuits. This also reduces signal distortion caused by the independent setting of protection and amplification components, ensuring the accuracy and safety of the external counterpulsation device in collecting gas pressure, and supporting the miniaturization design of the device.

2. The safety protection circuit for external counterpulsation according to claim 1, characterized in that, Also includes: +5V power supply; Resistor R21, one end connected to +5V power supply; Resistor R22 has one end connected to resistor R21 and the other end grounded, forming a series voltage divider circuit with resistor R21; The series connection of resistors R21 and R22 is connected to the power supply circuit of the pressure sensor, providing a stable reference voltage for the pressure sensor. This enables the output signal of the pressure sensor to be matched with the reference of the current-to-voltage conversion of resistor R23, ensuring the accuracy of signal acquisition.

3. The safety protection circuit for external counterpulsation according to claim 2, characterized in that, Also includes: +12V power supply; Capacitors C29 and C28 are connected in parallel and positioned between the +12V power supply and ground to form a power supply decoupling filter circuit, which suppresses power supply noise interference to the non-inverting amplifier circuit. Capacitor C30, with one end connected to the output terminal of U1A and the other end grounded, is used to filter out high-frequency noise amplified by U1A and optimize the signal quality input to U1B. Capacitor C31 is connected in series with resistor R26, and then in parallel with the feedback loop of U1B. Together with the RC filter network, they form a third-order active low-pass filter to further compress the cutoff frequency.

4. The safety protection circuit for external counterpulsation according to claim 3, characterized in that, Also includes: Test point TP2 is set between the TVS1 tube and the resistor R23 to detect the original current signal after transient protection. Test point TP4 is set at the connection node between the +12V power supply and the capacitor C29 to monitor the stability of the power supply. Interface J16 is the standard interface for the signal input of the pressure sensor. Pin 1 is connected to the signal input terminal of the TVS1 tube, and pin 2 is grounded, enabling quick plugging and unplugging of the sensor and the circuit and foolproof connection. Resistors R24 and R25 are connected in series between the output terminal of U1B and the signal input interface ADCIN-1 of the ADC sampling module to form current limiting protection and prevent the ADC sampling module from being damaged by overcurrent.

5. The safety protection circuit for external counterpulsation according to claim 4, characterized in that, Also includes: Test point XHB-2A is set on the signal transmission path between the TVS1 tube and the resistor R23. It is used to detect the original signal output by the pressure sensor after transient protection in real time, which facilitates circuit debugging and fault diagnosis and ensures the reliability of signal acquisition and transmission.

6. The safety protection circuit for external counterpulsation according to claim 5, characterized in that, Also includes: Capacitor C32 is connected at one end to the inverting input terminal of U1A and at the other end to the output terminal of U1A. It is connected in parallel with resistor R27 to form a hysteresis compensation network, which suppresses the self-excited oscillation of the non-inverting amplifier circuit and ensures the stability of low-noise amplification.

7. The safety protection circuit for external counterpulsation according to claim 6, characterized in that: The resistor R27 and the capacitor C32 form a hysteresis compensation network to prevent the circuit from oscillating.

8. The safety protection circuit for external counterpulsation according to claim 1, characterized in that: The non-inverting input terminal of U1A is grounded through the TVS1 transistor to suppress voltage surges.

9. The safety protection circuit for external counterpulsation according to claim 1, characterized in that: The -3dB cutoff frequency of the U1B is set to 50Hz to filter out high-frequency interference in the pressure signal.

10. A safety protection method for external counterpulsation, employing the safety protection circuit for external counterpulsation as described in claim 7, characterized in that, Includes the following steps: a. The counterpulsation control host is activated, which drives the compressor assembly to generate compressed gas. After being cooled by the gas storage tank assembly, the compressed gas is stored in the gas storage tank. The gas sensor monitors the pressure of the gas storage tank in real time. At the same time, the physiological signal acquisition module is triggered to collect human electrocardiogram, blood oxygen, blood pressure and other indicators to provide a basis for the counterpulsation rhythm. During this process, the MCU initializes the four safety protection circuits. Through the threshold setting circuit, appropriate pressure protection values ​​are set for the gas storage tank, calf, thigh and buttock airbags respectively. The +5V power supply provides a stable reference voltage for the pressure sensor through the voltage divider of resistor R21 and resistor R22. The +12V power supply ensures stable power supply through the decoupling filter circuit composed of capacitor C28 and capacitor C29. b. The pressure sensor collects the pressure data of the corresponding gas container in real time and outputs a 4-20mA current signal. One end of the TVS1 tube is connected to the signal output terminal of the pressure sensor and the other end is grounded to quickly clamp transient high voltage and avoid damage to the subsequent circuit. The test point TP2 detects the original current signal after transient protection. c. The protected current signal is converted into an initial voltage signal of 0.04 to 0.2V through the resistor R23, and input to the non-inverting amplifier circuit to amplify the signal by 10 times to 0.4V to 2V. The signal is then passed to the second-order active low-pass filter to filter out high-frequency noise. The capacitor C30 further optimizes the input signal quality. Finally, the optimized signal is transmitted to the ADC sampling module after being current-limited by the resistors R24 and R25. d. The ADC sampling module converts the analog signal into a digital signal and transmits it to the MCU. The MCU performs pressure monitoring and threshold comparison at the software level. At the same time, the optimized voltage signal is synchronously input into the comparison circuit and compared with the reference voltage of the threshold setting circuit in real time at the hardware level. If the pressure exceeds the set threshold, the comparator outputs a high-level signal. e. The three-input OR logic gates respectively receive the hardware overvoltage signal from the comparator, the software overvoltage signal from the MCU, and the manual trigger signal from the emergency stop switch. When any signal is high, a drive command is sent to the valve control circuit. When the emergency stop switch is pressed, it directly outputs a high level and triggers all vent valves to open synchronously. The MCU monitors the status of the emergency stop switch in real time. f. After receiving the instruction from the OR logic gate, the valve control circuit drives the vent valve to open quickly, releasing the overpressure gas in the corresponding gas container until the pressure returns to a safe range. Throughout the process, the counterpulsation control host continuously adjusts the inflation and deflation rhythm of the inflation and deflation components based on the feedback from the physiological signal acquisition module to ensure the normal progress of counterpulsation therapy. At the same time, all protection circuits are on duty throughout the process.

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