A fetal heart signal pickup front-end circuit and method

Abstract

The present application relates to the technical field of medical devices, and discloses a fetal heart signal pickup front-end circuit and method, which comprises a switch switching module, a first integration module, a second integration module, a differential amplification module and a control module; the input end of the first integration module is connected with the first output end of the switch switching module; the input end of the second integration module is connected with the second output end of the switch switching module; the first input end of the differential amplification module is connected with the output end of the first integration module, the second input end of the differential amplification module is connected with the output end of the second integration module, and the differential amplification module outputs a fetal heart Doppler envelope signal; and the control signal output end of the control module is connected with the control end of the switch switching module. The present application has the advantages of simple circuit, reliable performance, low power consumption, small size of functional components, which is conducive to product miniaturization and improvement of product use experience; and the present application has no special process requirement, is convenient for production, has low cost and is conducive to improvement of market competitiveness.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a fetal heart rate signal acquisition front-end circuit and method. Background Technology

[0002] Medical electronic products such as ultrasound Doppler fetal monitors and ultrasound Doppler fetal heart monitors have been widely used. They can all be used to monitor the fetal heart rate during the perinatal period (the period from 28 weeks of gestation to delivery).

[0003] Ultrasonic Doppler fetal monitors are commonly used in hospital obstetrics and gynecology departments and are essential equipment for prenatal examinations. These monitors track fetal heart rate for 10-30 minutes at a time, using changes in heart rate to determine if the fetus is experiencing oxygen deprivation, and consequently, whether fetal development is normal and the fetus's survival rate. Fetal heart rate monitoring data is crucial for medical professionals in assessing fetal development and can be a key factor in determining the need for intervention or a cesarean section. It is also a vital indicator for medical professionals in determining if a stillbirth has occurred.

[0004] Ultrasonic Doppler fetal heart rate monitors are mostly used at home, allowing for monitoring of the fetal heart rate anytime, anywhere. Pregnant women can monitor the fetal heart rate based on their own feelings or regularly to make a preliminary judgment on whether the fetal heart rate and fetal heart sounds are normal, serving as a preliminary basis for whether further testing at the hospital is needed.

[0005] Fetal heart rate Doppler technology is the core technology of medical electronic products such as ultrasound Doppler fetal monitors and ultrasound Doppler fetal heart monitors. The acquisition of fetal heart rate Doppler envelope signals is a key part of fetal heart rate Doppler technology.

[0006] Currently, the methods for acquiring fetal heart Doppler envelope signals have shortcomings, including complex circuitry, high failure rate, high power consumption, fixed ultrasonic frequency, and high cost. Summary of the Invention

[0007] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a fetal heart signal pickup front-end circuit, which outputs a fetal heart Doppler envelope signal with high fidelity, simple circuit, low cost, low power consumption, and the ability to process ultrasonic echo signals of multiple frequencies.

[0008] The present invention also proposes a method for acquiring fetal heart rate signals applied to the aforementioned fetal heart rate signal acquisition front-end circuit.

[0009] On one hand, the fetal heart rate signal acquisition front-end circuit according to an embodiment of the present invention includes a switch switching module, a first integration module, a second integration module, a differential amplification module, and a control module; the input terminal of the switch switching module is used to receive ultrasound echo signals; the input terminal of the first integration module is electrically connected to the first output terminal of the switch switching module; the input terminal of the second integration module is electrically connected to the second output terminal of the switch switching module; the first input terminal of the differential amplification module is electrically connected to the output terminal of the first integration module, the second input terminal of the differential amplification module is electrically connected to the output terminal of the second integration module, and the output terminal of the differential amplification module outputs a fetal heart rate Doppler envelope signal; the control signal output terminal of the control module is electrically connected to the control terminal of the switch switching module.

[0010] According to some embodiments of the present invention, the feedback terminal of the control module is also electrically connected to the output terminal of the differential amplifier module, and the control module controls the switching state of the switch switching module according to the changes in the peak and valley values ​​of the fetal heart Doppler envelope signal.

[0011] According to some embodiments of the present invention, the control signal output terminal of the control module includes a first control signal output port and a second control signal output port, and the switch switching module includes a single-channel switch unit and a dual-channel switch unit; the input terminal of the single-channel switch unit is used to receive ultrasonic echo signals, and the control terminal of the single-channel switch unit is electrically connected to the first control signal output port of the control module; the input terminal of the dual-channel switch unit is electrically connected to the output terminal of the single-channel switch unit, the first output terminal of the dual-channel switch unit is electrically connected to the input terminal of the first integration module, the second output terminal of the dual-channel switch unit is electrically connected to the input terminal of the second integration module, and the control terminal of the dual-channel switch unit is electrically connected to the second control signal output port of the control module.

[0012] According to some embodiments of the present invention, the single-channel switching unit includes a first operational amplifier and a first analog switch; the non-inverting input of the first operational amplifier is used to receive an ultrasonic echo signal, and the inverting input of the first operational amplifier is electrically connected to the output of the first operational amplifier; the input of the first analog switch is electrically connected to the output of the first operational amplifier, the output of the first analog switch is electrically connected to the input of the dual-channel switching unit, and the enable terminal of the first analog switch is electrically connected to the first control signal output port of the control module.

[0013] According to some embodiments of the present invention, the dual-channel switching unit includes a second analog switch, the input terminal of the second analog switch is electrically connected to the output terminal of the single-channel switching unit, the first output terminal of the second analog switch is electrically connected to the input terminal of the first integration module, the second output terminal of the second analog switch is electrically connected to the input terminal of the second integration module, and the enable terminal of the second analog switch is electrically connected to the second control signal output port of the control module.

[0014] According to some embodiments of the present invention, the circuit structures and parameters of the first integration module and the second integration module are the same. The first integration module includes a resistor R22 and a capacitor C22; the first end of the resistor R22 is electrically connected to the first output terminal of the switch module, and the second end of the resistor R22 is grounded; the first end of the capacitor C22 is electrically connected to both the first end of the resistor R22 and the first input terminal of the differential amplifier module, and the second end of the capacitor C22 is grounded. The second integration module includes a resistor R16 and a capacitor C23; the first end of the resistor R16 is electrically connected to the second output terminal of the switch module, and the second end of the resistor R16 is grounded; the first end of the capacitor C23 is electrically connected to both the first end of the resistor R16 and the second input terminal of the differential amplifier module, and the second end of the capacitor C23 is grounded.

[0015] According to some embodiments of the present invention, the differential amplifier module includes a second operational amplifier, a third operational amplifier, and a fourth operational amplifier; the non-inverting input terminal of the second operational amplifier is electrically connected to the output terminal of the first integrating module, and the inverting input terminal of the second operational amplifier is electrically connected to the output terminal of the second operational amplifier through resistor R7 and capacitor C24 respectively; the non-inverting input terminal of the third operational amplifier is electrically connected to the output terminal of the second integrating module, and the inverting input terminal of the third operational amplifier is electrically connected to the output terminal of the third operational amplifier through resistor R23 and capacitor C28 respectively, and the inverting input terminal of the third operational amplifier is further... The fourth operational amplifier is electrically connected to the inverting input of the second operational amplifier via capacitor C25 and resistor R26. The non-inverting input of the fourth operational amplifier is electrically connected to the output of the third operational amplifier via resistor R27. The non-inverting input of the fourth operational amplifier is also electrically connected to the reference voltage Vref via resistor R32. The inverting input of the fourth operational amplifier is electrically connected to the output of the second operational amplifier via resistor R24. The inverting input of the fourth operational amplifier is also electrically connected to the output of the fourth operational amplifier via resistor R31. The output of the fourth operational amplifier outputs the fetal heart rate Doppler envelope signal via resistor R33.

[0016] According to some embodiments of the present invention, the second operational amplifier, the third operational amplifier, and the fourth operational amplifier are operational amplifiers of the same specification, and the parameters of the resistor R7 and the resistor R23 are the same, as are the parameters of the capacitor C24 and the capacitor C28.

[0017] On the other hand, the fetal heart rate signal acquisition method according to an embodiment of the present invention is applied to the fetal heart rate signal acquisition front-end circuit according to the above embodiment of the present invention, including: The ultrasonic echo signal is acquired and input into the first integration module for integration; After time t1, the ultrasonic echo signal is switched to the second integration module for integration. After time t2, the ultrasonic echo signal is switched back to the first integration module for integration. After performing differential amplification on the first integral signal output by the first integral module and the second integral signal output by the second integral module, the corresponding fetal heart Doppler envelope signal is output.

[0018] According to some embodiments of the present invention, the method further includes the following steps: When the peak-to-trough value of the fetal heart Doppler envelope signal is lower than the first threshold, the time t1 and the time t2 are shortened; when the peak-to-trough value of the fetal heart Doppler envelope signal is higher than the second threshold, the time t1 and the time t2 are increased.

[0019] The embodiments of the present invention have at least the following beneficial effects: With the help of the switching module, the ultrasonic echo signal can be divided into two equally timed segments, which can then be input into the first and second integration modules for integration. The two integrated signals are then amplified by a differential amplification module, thereby enabling effective acquisition of the fetal heart rate Doppler envelope signal. When the ultrasonic echo signal changes, the fetal heart rate Doppler envelope signal will change accordingly. Based on the changes in the fetal heart rate Doppler envelope signal, it can be determined whether the fetal heart rate is normal. This circuit is simple, reliable, has low power consumption, and small functional components, which is conducive to product miniaturization and improves the user experience. Furthermore, it has no special process requirements, is easy to manufacture, and has low cost, which helps to enhance market competitiveness. It can be applied to medical ultrasonic Doppler fetal monitors as well as home ultrasonic Doppler fetal heart monitors.

[0020] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the circuit principle of the fetal heart rate signal acquisition front-end circuit according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the circuit principle of the fetal heart rate signal acquisition front-end circuit according to another embodiment of the present invention. Figure 3 This is a schematic diagram of the circuit principle of the fetal heart rate signal acquisition front-end circuit according to another embodiment of the present invention. Figure 4 for Figure 3 A schematic diagram of the circuit structure of the single-channel switch unit in the diagram; Figure 5 for Figure 3 A schematic diagram of the circuit structure of the dual-channel switch unit in the diagram; Figure 6 for Figure 3 The circuit structure diagram of the first and second integration modules in the diagram; Figure 7 for Figure 3 A schematic diagram of the circuit structure of the differential amplifier module in the image; Figure 8 for Figure 3 A schematic diagram of the integration timing of the fetal heart rate signal pickup front-end circuit; Figure 9 for Figure 3 A schematic diagram of the waveform of the fetal heart Doppler envelope signal output by the fetal heart signal pickup front-end circuit.

[0022] Figure label: Detailed Implementation

[0023] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with the embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0024] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. Furthermore, the descriptions of "upper," "lower," "left," "right," "top," and "bottom" used in this invention are only relative to the relative positional relationships of the various components of the invention in the accompanying drawings.

[0025] It should be noted that, unless otherwise specified, when one feature is referred to as having an "electrical connection" with another feature, the two features can be connected directly via pins, via cables, or via wireless transmission. Specific electrical connection methods are common to those skilled in the art, and they can implement the connection as needed.

[0026] Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and not for limiting the invention. The term "and / or" as used herein includes any combination of one or more of the associated listed items.

[0027] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various elements, these elements should not be limited to these terms. These terms are only used to distinguish elements of the same type from one another. For example, without departing from the scope of this disclosure, a first element may also be referred to as a second element, and similarly, a second element may also be referred to as a first element.

[0028] On the one hand, refer to Figure 1 According to an embodiment of the present invention, a fetal heart rate signal acquisition front-end circuit includes a switch module 100, a first integration module 200, a second integration module 300, a differential amplifier module 400, and a control module 500. The input terminal of the switch module 100 is used to receive ultrasound echo signals. The input terminal of the first integration module 200 is electrically connected to the first output terminal of the switch module 100. The input terminal of the second integration module 300 is electrically connected to the second output terminal of the switch module 100. The first input terminal of the differential amplifier module 400 is electrically connected to the output terminal of the first integration module 200, and the second input terminal of the differential amplifier module 400 is electrically connected to the output terminal of the second integration module 300. The output terminal of the differential amplifier module 400 outputs a fetal heart rate Doppler envelope signal. The control signal output terminal of the control module 500 is electrically connected to the control terminal of the switch module 100.

[0029] The control module 500 can control the state of the switch switching module 100 at regular intervals, so that the ultrasound echo signal can be evenly divided into two paths and enter the first integration module 200 and the second integration module 300 for integration calculation. Finally, it is input to the differential amplification module 400 for differential calculation to output the corresponding fetal heart Doppler envelope signal. When the ultrasound echo signal changes, there will be a difference between the two integrated signals, and the fetal heart Doppler envelope signal will change accordingly. Therefore, the change in the integral difference between the two paths can reflect the Doppler effect of fetal heart rate regulation.

[0030] Reference Figure 2 In some embodiments of the present invention, the feedback terminal of the control module 500 is also electrically connected to the output terminal of the differential amplifier module 400. The control module 500 controls the switching state of the switch switching module 100 according to the changes in the peak and valley values ​​of the fetal heart Doppler envelope signal. By monitoring the changes in the fetal heart Doppler envelope signal, the control module 500 can adjust the integration duration of the ultrasound echo signal in the two channels in real time, thereby avoiding the waveform of the fetal heart Doppler envelope signal being too small or too large and overflowing. That is, by controlling the integration duration of the two channels, the difference between the two signals can be changed, thereby controlling the waveform change of the output fetal heart Doppler envelope signal within an appropriate range, thus effectively observing whether the fetal heart rate is normal, further improving reliability and adaptability. The present invention adjusts in real time according to the fetal heart Doppler envelope signal, and can monitor ultrasound echo signals with frequencies within a fixed range. Specifically, the monitoring range will vary depending on the integration duration of the two channels. Those skilled in the art can make corresponding settings according to actual needs, thereby acquiring ultrasound echo signals within a corresponding fixed range.

[0031] It is understood that the switch switching module 100 is designed to input the ultrasonic echo signal into the first integration module 200 or the second integration module 300 within a limited time period. That is, the switch switching module 100 mainly functions as a single-pole double-throw switch. Therefore, those skilled in the art can combine the switch switching module 100 to set up the corresponding circuit structure to achieve the main required functions.

[0032] Reference Figure 3In some embodiments of the present invention, the control signal output terminal of the control module 500 includes a first control signal output port and a second control signal output port, and the switch switching module 100 includes a single-channel switch unit 110 and a dual-channel switch unit 120; the input terminal of the single-channel switch unit 110 is used to receive ultrasonic echo signals, and the control terminal of the single-channel switch unit 110 is electrically connected to the first control signal output port of the control module 500; the input terminal of the dual-channel switch unit 120 is electrically connected to the output terminal of the single-channel switch unit 110, the first output terminal of the dual-channel switch unit 120 is electrically connected to the input terminal of the first integration module 200, the second output terminal of the dual-channel switch unit 120 is electrically connected to the input terminal of the second integration module 300, and the control terminal of the dual-channel switch unit 120 is electrically connected to the second control signal output port of the control module 500. By controlling the state of the dual-channel switch unit 120 through the control module 500, the ultrasonic echo signal can be split into two paths and sent to the first integration module 200 or the second integration module 300 respectively. Simultaneously, by controlling the on / off state of the single-channel switch unit 110 through the control module 500, the integration time of one of the signals can be controlled independently. This allows for the effective acquisition of ultrasonic echo signals at a fixed frequency. By limiting the time of splitting the ultrasonic echo signal into two paths, the splitting time of the acquired ultrasonic echo signal can be controlled within a fixed range. That is, the maximum duration of each segmented ultrasonic echo signal is within the limited range. This avoids the difference between the two ultrasonic echo signals becoming too small due to excessive time, which could lead to an excessively small waveform of the final fetal heart rate Doppler envelope signal, potentially resulting in no signal output and misjudgment of the fetal heart rate. Therefore, those skilled in the art, based on their understanding of conventional fetal heart rate changes, can effectively limit the duration of the split ultrasonic echo signal in combination with the circuit of this invention, thereby effectively displaying the acquired ultrasonic echo signal and effectively improving the accuracy and reliability of monitoring. By coordinating the control module 500 with the control of the state duration of the single-channel switch unit 110 and the dual-channel switch unit 120, the present invention can effectively monitor ultrasonic echo signals with frequencies in the range of 1MHz to 3MHz.

[0033] Reference Figure 4In some embodiments of the present invention, the single-channel switch unit 110 includes a first operational amplifier U8 and a first analog switch U2; the non-inverting input terminal of the first operational amplifier U8 is used to receive ultrasonic echo signals, the inverting input terminal of the first operational amplifier U8 is electrically connected to the output terminal of the first operational amplifier U8, the power supply terminal of the first operational amplifier U8 is electrically connected to the power supply VCC through a resistor R14, and the power supply terminal of the first operational amplifier U8 is also grounded through a capacitor C13; the input terminal of the first analog switch U2 is electrically connected to the output of the first operational amplifier U8, the output terminal of the first analog switch U2 is electrically connected to the input terminal of the dual-channel switch unit 120, and the enable terminal of the first analog switch U2 is electrically connected to the first control signal output port of the control module 500. In conjunction with the first operational amplifier U8, the acquired ultrasonic echo signal can be amplified, thereby improving the accuracy of subsequent signal integration. At the same time, in conjunction with the first analog switch U2, the integration time of a single ultrasonic echo signal can be controlled. That is, by controlling the on and off time of the first analog switch U2, the control module 500 can control the integration time of the subsequent single ultrasonic echo signal.

[0034] It is understood that, based on the working principle of the first operational amplifier U8 or the first analog switch U2, those skilled in the art can use circuit components with corresponding specifications according to actual needs. In this embodiment, the first operational amplifier U8 is model RS8751XF, and the first analog switch U2 uses signal BL1551. (Refer to...) Figure 4 The specific line connection relationships are as follows: Figure 4 As shown in the diagram, setting the signal P1 of the first control signal output port of the control module 500 high or low can control the on / off state of the first analog switch U2.

[0035] It should be noted that although the first operational amplifier U8 and the first analog switch U2 are conventional chips available on the market, the actual circuit structure of the single-channel switch unit 110 can also be other circuit structures. Those skilled in the art can set up the corresponding circuit structure according to actual needs to realize the working principle of the single-channel switch unit 110.

[0036] Reference Figure 5In some embodiments of the present invention, the dual-channel switching unit 120 includes a second analog switch U3. The input terminal of the second analog switch U3 is electrically connected to the output terminal of the single-channel switching unit 110. The first output terminal of the second analog switch U3 is electrically connected to the input terminal of the first integrator module 200. The second output terminal of the second analog switch U3 is electrically connected to the input terminal of the second integrator module 300. The enable terminal of the second analog switch U3 is electrically connected to the second control signal output port of the control module 500. With the control of the second analog switch U3 by the control module 500, the ultrasonic echo signal can be input to the first integrator module 200 or the second integrator module 300 within a corresponding time period, thereby achieving isochronous and uniform segmentation of the ultrasonic echo signal.

[0037] It is understood that, based on the working principle of the second analog switch U3, those skilled in the art can use circuit components with appropriate specifications according to actual needs. In this embodiment, the signal used by the second analog switch U3 is BL1551, referring to... Figure 5 The specific line connection relationships are as follows: Figure 5 As shown in the diagram, setting the signal P2 of the second control signal output port of the control module 500 high or low allows control over the connection state of the second analog switch U3. This allows the amplified ultrasonic echo signal to be input into either the first integrator module 200 or the second integrator module 300.

[0038] It should be noted that although the second analog switch U3 is a conventional chip on the market, the actual circuit structure of the dual-channel switch unit 120 can also be other circuit structures. Those skilled in the art can set up the corresponding circuit structure according to actual needs to realize the working principle of the dual-channel switch unit 120.

[0039] Reference Figure 6In some embodiments of the present invention, the circuit structures and parameters of the first integration module 200 and the second integration module 300 are the same. The first integration module 200 includes a resistor R22 and a capacitor C22. The first end of the resistor R22 is electrically connected to the first output terminal of the switch module 100, i.e., electrically connected to the first output terminal of the corresponding dual-channel switch unit 120, and the second end of the resistor R22 is grounded. The first end of the capacitor C22 is electrically connected to both the first end of the resistor R22 and the first input terminal of the differential amplifier module 400, and the second end of the capacitor C22 is grounded. The second integration module 300 includes a resistor R16 and a capacitor C23. The first end of the resistor R16 is electrically connected to the second output terminal of the switch module 100, i.e., electrically connected to the second output terminal of the corresponding dual-channel switch unit 120, and the second end of the resistor R16 is grounded. The first end of the capacitor C23 is electrically connected to both the first end of the resistor R16 and the second input terminal of the differential amplifier module 400, and the second end of the capacitor C23 is grounded. By keeping the circuit structure and parameters of the first integrator module 200 and the second integrator module 300 identical, the same integration operations can be performed on the corresponding ultrasonic echo signals. When the frequency of the ultrasonic echo signal remains unchanged (no Doppler effect), the integral values ​​of the first integrator module 200 and the second integrator module 300 are the same; when the frequency of the ultrasonic echo signal changes (Doppler effect), the integral values ​​of the first integrator module 200 and the second integrator module 300 will be different. Therefore, the difference between the integral values ​​of the first integrator module 200 and the second integrator module 300 is correlated with the change in the echo signal frequency, and the change in the integral difference between the first integrator module 200 and the second integrator module 300 can reflect the Doppler effect of fetal heartbeat.

[0040] Reference Figure 7In some embodiments of the present invention, the differential amplifier module 400 includes a second operational amplifier U10A, a third operational amplifier U10D, and a fourth operational amplifier U10C; the non-inverting input terminal of the second operational amplifier U10A is electrically connected to the output terminal of the first integration module 200, and the inverting input terminal of the second operational amplifier U10A is electrically connected to the output terminal of the second operational amplifier U10A through resistor R7 and capacitor C24, respectively; the power supply terminal of the second operational amplifier U10A is also electrically connected to power supply VCC and capacitor C32, respectively; the non-inverting input terminal of the third operational amplifier U10D is electrically connected to the output terminal of the second integration module 300, and the inverting input terminal of the third operational amplifier U10D is electrically connected to the output terminal of the third operational amplifier U10D through resistor R23 and capacitor C28, respectively. The third operational amplifier U10D is electrically connected to the inverting input of the second operational amplifier U10A via capacitor C25 and resistor R26. The non-inverting input of the fourth operational amplifier U10C is electrically connected to the output of the third operational amplifier U10D via resistor R27. The non-inverting input of the fourth operational amplifier U10C is also electrically connected to the reference voltage Vref via resistor R32. The inverting input of the fourth operational amplifier U10C is electrically connected to the output of the second operational amplifier U10A via resistor R24. The inverting input of the fourth operational amplifier U10C is also electrically connected to the output of the fourth operational amplifier U10C via resistor R31. The output of the fourth operational amplifier U10C outputs the fetal heart Doppler envelope signal via resistor R33. By combining the second operational amplifier U10A, the third operational amplifier U10D, and the fourth operational amplifier U10C, an instrumentation amplifier can be built. This not only effectively reduces circuit costs and meets the requirement of low cost, but also effectively improves the accuracy of differential amplification and enhances the reliability of fetal heart rate monitoring.

[0041] In some embodiments of the present invention, the second operational amplifier U10A, the third operational amplifier U10D, and the fourth operational amplifier U10C are operational amplifiers of the same specifications, and the parameters of the resistors R7 and R23 are the same, as are the parameters of the capacitors C24 and C28. Using the same parameters for the relevant operational amplifiers and circuit components can improve the performance of the differential amplifier module 400, enabling high-precision differential amplification of the two integrated signals, resulting in higher accuracy of the output fetal heart rate Doppler envelope signal and improved reliability of fetal heart rate monitoring.

[0042] In some embodiments of the present invention, the control module 500 is a conventional processor. Those skilled in the art can select a suitable processor based on the control principle of the control module 500 according to the present invention. Specific selection and structure will not be described in detail. In practical applications, the control module 500 of the present invention uses a microcontroller.

[0043] On the other hand, the fetal heart rate signal acquisition method according to an embodiment of the present invention is applied to the fetal heart rate signal acquisition front-end circuit according to the above embodiment of the present invention, including: The switch switching module 100 acquires the ultrasonic echo signal, and the control module 500 controls the switch switching module 100 to input the ultrasonic echo signal to the first integration module 200 for integration. After time t1, the control module 500 switches the state of the control switch switching module 100 and switches the ultrasonic echo signal to the second integration module 300 for integration. After time t2, the control module 500 switches the state of the control switch switching module 100 again and switches the ultrasonic echo signal to the first integration module 200 for integration again. The differential amplification module 400 performs differential amplification operations on the first integral signal output by the first integral module 200 and the second integral signal output by the second integral module 300, and then outputs the corresponding fetal heart Doppler envelope signal.

[0044] Specifically, in combination Figures 3 to 8 To further illustrate the method steps of the present invention, the method can be converted into corresponding integration timing and steps for detailed explanation: Step 1: When the signal P1 of the first control signal output port of the control module 500 is set low, the ultrasonic echo signal is amplified by the first operational amplifier U8 and then connected to the fourth pin of the first analog switch U2. When the signal P2 of the second control signal output port of the control module 500 is set high, the ultrasonic echo signal is input to the first integration module 200 for integration. The integration time is time t1, and the time t1 is limited by the program of the control module 500. Step 2: When the signal P1 of the first control signal output port of the control module 500 is set high, the ultrasonic echo signal is disconnected from the fourth pin of the first analog switch U2, and the loop integration of the first integration module 200 is interrupted. Step 3: When the signal P1 of the first control signal output port of the control module 500 is set low, the ultrasonic echo signal is amplified by the first operational amplifier U8 and then connected to the fourth pin of the first analog switch U2. When the signal P2 of the second control signal output port of the control module 500 is set low, the ultrasonic echo signal is input to the second integration module 300 for integration. The integration time is t2, and the time t2 is limited by the program of the control module 500. Step 4: When the signal P1 of the first control signal output port of the control module 500 is set high, the ultrasonic echo signal is disconnected from the fourth pin of the first analog switch U2, and the integration of the INTEGRAL2 circuit is interrupted.

[0045] The above integration timing steps are performed cyclically under the control of the microcontroller embedded software used in the control module 500, so that the acquired ultrasonic echo signal can be divided into two equal and uniform channels to complete the integration of two channels. In this invention, the duration of time t1 and time t2 in the same period is the same, and time t1 and time t2 are the duration of the first analog switch U2 being connected by the control module 500.

[0046] The present invention, by synchronously setting a single-channel switch unit 110 and a dual-channel switch unit 120, wherein the control module 500 controls the switching state of the dual-channel switch unit 120, can ensure that the periodic variation of the ultrasonic echo signal input to the two channels is fixed, and can also limit the longest integration time of the ultrasonic echo signal in the first integration module 200 or the second integration module 300 respectively. In conjunction with the single-channel switch unit 110, the integration time of the ultrasonic echo signal in the first integration module 200 or the second integration module 300 can be controlled separately, thereby limiting the period and integration time of the ultrasonic echo signal processing of the present invention, and thus enabling the acquisition of ultrasonic echo signals within a limited frequency range.

[0047] In some embodiments of the present invention, the following steps are also included: The fetal heart Doppler envelope signal is fed back to the control module 500 in real time. When the peak and valley values ​​of the fetal heart Doppler envelope signal are lower than the first threshold, the control module 500 shortens the time t1 and the time t2. When the peak and valley values ​​of the fetal heart Doppler envelope signal are higher than the second threshold, the control module 500 increases the time t1 and the time t2.

[0048] It should be noted that the setting of the first threshold and the second threshold can be set according to the peak and valley value range or the fetal heart rate change pattern that can be collected based on the actual circuit structure. Those skilled in the art can make corresponding adjustments and set the fetal heart rate change pattern according to the actual circuit structure parameters.

[0049] Specifically, refer to Figure 9When the waveform of the output fetal heart rate Doppler envelope signal is within the normal range (i.e., the waveform is normal), time t1 and time t2 are no longer adjusted. When the peak-to-trough value of the fetal heart rate Doppler envelope signal is lower than a first threshold (i.e., the envelope waveform is too small), time t1 and time t2 can be shortened. When the peak-to-trough value of the fetal heart rate Doppler envelope signal is higher than a second threshold (i.e., the envelope waveform overflows), time t1 and time t2 can be increased. In this invention, the duration of time t1 and time t2 within the same cycle is the same; therefore, the magnitude of any increase or decrease in time t1 and time t2 remains consistent, ensuring the accuracy of the fetal heart rate Doppler envelope signal.

[0050] According to an embodiment of the present invention, by such a configuration, at least the following effects can be achieved: In conjunction with the switch switching module 100, the ultrasonic echo signal can be uniformly divided into two channels at the same time, and then the two signals can be input to the first integration module 200 and the second integration module 300 respectively for integration. The differential amplification module 400 performs differential amplification on the two integrated signals, thereby enabling effective pickup of the fetal heart rate Doppler envelope signal. When the ultrasonic echo signal changes, the fetal heart rate Doppler envelope signal will change accordingly. Based on the changes in the fetal heart rate Doppler envelope signal, it can be determined whether the fetal heart rate is normal. This circuit is simple, reliable, has low power consumption, and small functional components, which is conducive to product miniaturization and improves the user experience. Furthermore, it has no special process requirements, is easy to manufacture, and has low cost, which helps to enhance market competitiveness. It can be applied to medical ultrasonic Doppler fetal monitors as well as home ultrasonic Doppler fetal heart monitors.

[0051] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this disclosure, as long as they achieve the same technical effects, should be included within the scope of protection of this disclosure and fall under the protection scope of the present invention. Within the protection scope of the present invention, the technical solutions and / or implementation methods can have various modifications and variations.

Claims

1. A fetal heart rate signal acquisition front-end circuit, characterized in that, include: A switch switching module (100) is provided, the input of which is used to receive ultrasonic echo signals; The first integration module (200) is electrically connected to the first output terminal of the switch switching module (100); The second integration module (300) has its input terminal electrically connected to the second output terminal of the switch switching module (100); A differential amplifier module (400) is provided, wherein the first input terminal of the differential amplifier module (400) is electrically connected to the output terminal of the first integration module (200), the second input terminal of the differential amplifier module (400) is electrically connected to the output terminal of the second integration module (300), and the output terminal of the differential amplifier module (400) outputs the fetal heart Doppler envelope signal. The control module (500) is electrically connected to the control terminal of the switch switching module (100). The switch switching module (100) can divide the ultrasonic echo signal into two equal and uniform channels, and then input the two signals into the first integration module (200) and the second integration module (300) for integration.

2. The fetal heart rate signal acquisition front-end circuit according to claim 1, characterized in that, The feedback terminal of the control module (500) is also electrically connected to the output terminal of the differential amplifier module (400). The control module (500) controls the switching state of the switch switching module (100) according to the changes in the peak and valley values ​​of the fetal heart Doppler envelope signal.

3. The fetal heart rate signal acquisition front-end circuit according to claim 1 or 2, characterized in that, The control signal output terminal of the control module (500) includes a first control signal output port and a second control signal output port, and the switch switching module (100) includes: A single-channel switch unit (110) is provided, the input terminal of which is used to receive ultrasonic echo signals, and the control terminal of which is electrically connected to the first control signal output port of the control module (500). A dual-channel switch unit (120) is provided, wherein the input terminal of the dual-channel switch unit (120) is electrically connected to the output terminal of the single-channel switch unit (110), the first output terminal of the dual-channel switch unit (120) is electrically connected to the input terminal of the first integrator module (200), the second output terminal of the dual-channel switch unit (120) is electrically connected to the input terminal of the second integrator module (300), and the control terminal of the dual-channel switch unit (120) is electrically connected to the second control signal output port of the control module (500).

4. The fetal heart rate signal pickup front-end circuit according to claim 3, characterized in that: The single-channel switch unit (110) includes: A first operational amplifier, wherein the non-inverting input of the first operational amplifier is used to receive ultrasonic echo signals, and the inverting input of the first operational amplifier is electrically connected to the output of the first operational amplifier. The first analog switch has its input terminal electrically connected to the output of the first operational amplifier, its output terminal electrically connected to the input terminal of the dual-channel switch unit (120), and its enable terminal electrically connected to the first control signal output port of the control module (500).

5. The fetal heart rate signal acquisition front-end circuit according to claim 4, characterized in that: The dual-channel switching unit (120) includes a second analog switch. The input terminal of the second analog switch is electrically connected to the output terminal of the single-channel switching unit (110). The first output terminal of the second analog switch is electrically connected to the input terminal of the first integrator module (200). The second output terminal of the second analog switch is electrically connected to the input terminal of the second integrator module (300). The enable terminal of the second analog switch is electrically connected to the second control signal output port of the control module (500).

6. The fetal heart rate signal acquisition front-end circuit according to claim 1 or 2, characterized in that, The circuit structure and parameters of the first integration module (200) and the second integration module (300) are the same, wherein, The first integration module (200) includes: Resistor R22, the first end of which is electrically connected to the first output terminal of the switch switching module (100), and the second end of resistor R22 is grounded; Capacitor C22, the first end of which is electrically connected to the first end of resistor R22 and the first input terminal of differential amplifier module (400), and the second end of capacitor C22 is grounded; The second integration module (300) includes: Resistor R16, the first end of which is electrically connected to the second output terminal of the switch switching module (100), and the second end of resistor R16 is grounded; Capacitor C23, the first end of which is electrically connected to the first end of resistor R16 and the second input end of differential amplifier module (400), and the second end of capacitor C23 is grounded.

7. The fetal heart rate signal pickup front-end circuit according to claim 1 or 2, characterized in that, The differential amplifier module (400) includes: The second operational amplifier has its non-inverting input terminal electrically connected to the output terminal of the first integrating module (200), and its inverting input terminal electrically connected to the output terminal of the second operational amplifier through resistor R7 and capacitor C24 respectively. The third operational amplifier has its non-inverting input terminal electrically connected to the output terminal of the second integration module (300), and its inverting input terminal electrically connected to the output terminal of the third operational amplifier through resistor R23 and capacitor C28, respectively. The inverting input terminal of the third operational amplifier is also electrically connected to the inverting input terminal of the second operational amplifier through capacitor C25 and resistor R26 in sequence. The fourth operational amplifier has its non-inverting input terminal electrically connected to the output terminal of the third operational amplifier via resistor R27. The non-inverting input terminal of the fourth operational amplifier is also electrically connected to the reference voltage Vref via resistor R32. The inverting input terminal of the fourth operational amplifier is electrically connected to the output terminal of the second operational amplifier via resistor R24. The inverting input terminal of the fourth operational amplifier is also electrically connected to the output terminal of the fourth operational amplifier via resistor R31. The output terminal of the fourth operational amplifier outputs the fetal heart rate Doppler envelope signal via resistor R33.

8. The fetal heart rate signal pickup front-end circuit according to claim 7, characterized in that: The second operational amplifier, the third operational amplifier, and the fourth operational amplifier are operational amplifiers of the same specification, and the parameters of the resistor R7 and the resistor R23 are the same, as are the parameters of the capacitor C24 and the capacitor C28.

9. A method for acquiring fetal heart rate signals, characterized in that: The circuit is applied to the fetal heart rate signal acquisition front-end circuit as described in any one of claims 1 to 8, comprising: The ultrasonic echo signal is acquired and input into the first integration module (200) for integration; After time t1, the ultrasonic echo signal is switched to the second integration module (300) for integration. After time t2, the ultrasonic echo signal is switched back to the first integration module (200) for integration. The durations of time t1 and time t2 within the same period are the same. After performing differential amplification operations on the first integral signal output by the first integral module (200) and the second integral signal output by the second integral module (300), the corresponding fetal heart Doppler envelope signal is output.

10. The fetal heart rate signal acquisition method according to claim 9, characterized in that, It also includes the following steps: When the peak-to-trough value of the fetal heart Doppler envelope signal is lower than the first threshold, the time t1 and the time t2 are shortened; when the peak-to-trough value of the fetal heart Doppler envelope signal is higher than the second threshold, the time t1 and the time t2 are increased.

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