Detailed Description
The application is described in further detail below with reference to the drawings and examples. It is specifically noted that the following examples are only for illustrating the present application, but do not limit the scope of the present application. Likewise, the following examples are only some, but not all, of the examples of the present application, and all other examples, which a person of ordinary skill in the art would obtain without making any inventive effort, are within the scope of the present application.
The application firstly proposes a lead falling-off detection circuit, as shown in fig. 1, fig. 1 is a schematic circuit diagram of an embodiment of the lead falling-off detection circuit of the application. In this embodiment, the pull-up resistor R1 or the pull-down resistor R2 is used to monitor the falling of the leads, the input end INP and the input end INN are both connected with the leads, when a certain lead falls off from the target detection body, the input end INP connected with the lead is pulled up to the high level of AVDD due to the effect of the pull-up resistor R1, the high level is obtained through the comparator PGA, and the state value of the fallen lead is set. The detection process may be performed by a separate Analog-to-digital converter (ADC) chip, or by an Analog circuit in combination with a micro control unit (Micro Controller Unit, MCU) (i.e., a control circuit in the subsequent embodiment) and an ADC built in the MCU.
In another embodiment, as shown in fig. 2, fig. 2 is a schematic circuit diagram of a lead falling off detection circuit according to an embodiment of the application. In this embodiment, excitation current is used to realize the detection of lead falling, the input end INP and the input end INN are both connected with the lead, when a certain lead falls off from the target detection body, the input end INP connected with the lead is pulled up to the high level of AVDD due to the effect of the excitation current, the high level is obtained through the comparator PGA, and the state value of the fallen lead is set. The detection process can be completed by a single ADC chip or by an analog circuit matched with MCU, an ADC of the MCU, and the like.
As shown in fig. 1 and 2, when the pull-up resistor R1 is too small (or the exciting current is large), the input impedance of the lead drop-off detection circuit is small, when the skin impedance of the target detection body is large, according to ohm's law, the input end INP of the comparator PGA forms a voltage division with AVDD and the output voltage of the lead, when the skin impedance is large enough and the pull-up resistor R1 is small enough, the input voltage of the electrocardiograph signal is divided into a larger voltage, so that the input voltage of the electrocardiograph signal approaches the AVDD voltage, and exceeds the maximum input voltage of the comparator PGA (the input voltage of the ADC chip should be lower than the voltage division of the pull-up resistor R1 or the voltage of the exciting current), so that the waveform corresponding to the whole electrocardiograph signal becomes a straight line, or a disordered waveform.
In order to improve the above-mentioned scheme, the present application further provides a correction circuit for lead drop detection, as shown in fig. 3, and fig. 3 is a schematic circuit diagram of an embodiment of the correction circuit for lead drop detection according to the present application. The correction circuit of the present embodiment includes: a detection signal generation circuit 11, a lead 12, another lead 13, and a control circuit 15; wherein the detection signal generation circuit 11 is used for generating an impedance detection signal; the leads 12 are respectively connected with the target detection body and the detection signal generating circuit 11 and are used for transmitting an impedance detection signal to the target detection body so as to carry out impedance detection on the target detection body; the lead 13 is connected with the target detection body and is used for acquiring a feedback signal of the target detection body; the control circuit 15 is connected to the detection signal generating circuit 11 and the measurement circuit 14, and is used for controlling the detection signal generating circuit 11 to generate an impedance detection signal, acquiring a first correction parameter based on the feedback signal, and correcting the input impedance of the guide-drop detection circuit (not shown) by using the first correction parameter; wherein the dropout detection circuit is connected to the lead 12 and/or the lead 13.
The drop detection circuit of this embodiment can refer to the above-described embodiments.
The target detection body of the present embodiment may be a living organism such as a human body, which needs to be electrocardiographically monitored.
When the lead 12 (lead 13) is in contact with the target object, an electric signal is output, and when the lead is detached from the target object, no electric signal is output, and the detachment detection circuit converts the state of the electric signal output by the lead 12 (lead 13) and the state of the electric signal not output into different detection result signals, and the control circuit 15 determines whether the lead 12 (lead 13) is detached from the target object based on the detection result signals.
In other embodiments, measurement circuitry may be included, coupled to lead 13, for obtaining a feedback signal from lead 13; the measurement circuit 14 may perform primary signal processing on the feedback signal, in addition to sending the feedback signal output by the lead 13 to the control circuit 15, so as to reduce signal interference and improve accuracy of impedance detection.
The control circuit 15 calculates the feedback signal through an impedance matrix algorithm to obtain an impedance value of the target object, obtains a first correction parameter (may be an input impedance corresponding to the impedance value) corresponding to the impedance value, and adjusts the input impedance of the shedding detection circuit (adjusts the current input impedance to be the input impedance corresponding to the impedance value) by using the first correction parameter.
As shown in fig. 1 and 2, the resistance values of the pull-up resistor R1 and the pull-down resistor R2 in fig. 1 may be specifically adjusted, or the magnitude of the excitation current shown in fig. 2 may be adjusted. The impedance value of the target detector 16 is large, and the impedance values of the pull-up resistor R1 and the pull-down resistor R2 may be increased or the excitation current may be decreased.
The correction circuit for lead falling detection of the embodiment controls the detection signal generation circuit 11 to generate an impedance detection signal through the control circuit 15, and transmits the impedance detection signal to a target detection body through the lead 12 so as to perform impedance detection on the target detection body; then, the feedback signal of the target detection body is obtained by using the lead 13 and is transmitted to the control circuit 15, the control circuit 15 obtains the first correction parameter based on the feedback signal, and adjusts the input impedance of the falling detection circuit by using the first correction parameter so as to improve the matching degree between the impedance of the target detection body and the input impedance of the falling detection circuit, so that the problem of false alarm caused by falling of the lead due to small pull-up resistance of the falling detection circuit or large skin impedance when the current of the excitation current is large in the prior art can be improved, and the problem of reduced sensitivity of the falling detection of the lead due to large pull-up resistance of the falling detection circuit or small current of the excitation current can be improved, and therefore, the embodiment can improve the accuracy of the falling detection of the lead.
Alternatively, the detection signal generation circuit 11 of the present embodiment includes: a sine wave generation circuit 111; the sine wave generating circuit 111 is connected to the control circuit 15 and the lead 12, respectively, and is configured to generate an impedance detection signal under control of the control circuit 15 and transmit the impedance detection signal to the lead 12.
The impedance detection signal generated by the sine wave generation circuit 111 is a high-frequency sine wave signal.
Because the feedback signal obtained by the lead 13 from the target detection body not only includes the impedance feedback signal of the target detection body to the impedance detection signal, but also includes the electrocardiographic signal of the target detection body, and the electrocardiographic signal is a low-frequency signal, the detection signal generating circuit 11 is adopted in this embodiment to obtain a high-frequency impedance detection signal, so that the impedance feedback signal of the target detection body is a high-frequency signal and can be distinguished from a low-frequency electrocardiographic signal, so as to increase the accuracy of impedance detection and electrocardiographic monitoring.
In other embodiments, the detection signal generating circuit 11 further includes an excitation circuit connected to the sine wave generating circuit 111 and the lead 12, respectively, for amplifying the high frequency sine wave signal to obtain an impedance detection signal.
Optionally, the correction circuit of the present embodiment further includes a first filter circuit 17 connected to the measurement circuit 14 and the control circuit 15, respectively, for performing filtering processing on the feedback signal to obtain an impedance feedback signal, and the control circuit 15 obtains the first correction parameter based on the impedance feedback signal.
From the above analysis, the impedance feedback signal is a high-frequency signal, and the electrocardiograph signal is a low-frequency signal, so the first filter circuit 17 of the present embodiment is a high-pass filter circuit for filtering the low-frequency electrocardiograph signal from the feedback signal, so as to obtain the high-frequency impedance feedback signal.
Optionally, the correction circuit of this embodiment further includes a first gain circuit 18 connected to the control circuit 15 and the first filter circuit 17, respectively, for amplifying the impedance feedback signal, and transmitting the amplified impedance feedback signal to the control circuit 15, so as to improve the accuracy of impedance detection.
Optionally, the correction circuit of this embodiment further includes an ADC19 connected to the first gain circuit 18 and the control circuit 15, respectively, for performing analog-to-digital conversion on the amplified impedance feedback signal.
In other embodiments, the ADC may be integrated in the control circuit.
The control circuit 15 in this embodiment is an MCU, and in other embodiments, a non-integrated circuit may be used to implement the control circuit.
Optionally, the correction circuit of the present embodiment further includes: a coupling circuit (not shown), such as a capacitive coupling capacitor, is connected to the lead 12 and the detection signal generating circuit 11, respectively, for coupling the impedance detection signal into the lead 12 to be output to the target detection body.
Specifically, the lead 12 is connected to the target detection body through an electrode pad, and the other end of the lead 12 is connected to the sine wave generation circuit 111 through a capacitive coupling circuit; the sine wave generation circuit 111 is switched by the MCU and transmits frequency. The lead 13 is connected with the target detection body through an electrode plate, the acquired feedback signal of the lead 13 is connected to the ADC19 after being filtered by the high-pass filter circuit and amplified by the first gain circuit 18, and the analog signal is converted into a digital signal through the ADC19 and is transmitted to the MCU for data calculation processing.
When the impedance value of the target detection body needs to be acquired, the MCU generates a high-frequency square wave signal (which may be several clock signals with different frequencies), and the square wave signal generates a sinusoidal excitation signal with a corresponding frequency, that is, a high-frequency sinusoidal wave signal, through the sinusoidal wave generating circuit 111. The sinusoidal excitation signal is coupled from the electrocardio-electrode to a different portion of the target subject via at least one pair of excitation electrodes (excitation circuit 112). The sine wave excitation signal forms voltage drop under the equivalent impedance network of the target detection body, different voltage drop signals are obtained through the measuring circuit 14, the voltage drop signals are sent to the MCU through the ADC after being processed by the high-pass filter circuit and the like, the MCU obtains an impedance matrix through the filter algorithm, and then the impedance value of the target detection body is obtained through the impedance algorithm. The multi-path test can obtain the impedance values of different parts of the target detection body, the average impedance of the target detection body and other data.
After the MCU obtains the impedance value, the resistance value (or the exciting current) of the pull-up resistor and the pull-down resistor of the drop-off detection circuit are adaptively adjusted, so that a better lead drop-off detection effect is obtained. The pull-up resistor and the pull-down resistor are adjustable resistors, and the exciting current is adjustable exciting current.
In another embodiment, as shown in fig. 8, fig. 8 is a schematic circuit diagram of a lead falling off detection circuit according to an embodiment of the application. The correction circuit for lead falling detection in this embodiment at least includes: a detection signal generation circuit 11 for generating an impedance detection signal; a switching circuit 81 and a detection signal generation circuit; a lead network 82 including a plurality of leads connected to the switching circuit 81 and the target detector, respectively; a control circuit 15, respectively connected to the detection signal generating circuit 11 and the switching circuit 81, for controlling the detection signal generating circuit to generate an impedance detection signal, and for controlling the switching circuit 81 to selectively connect the detection signal generating circuit with one of the plurality of leads 12, and to obtain a feedback signal of the target detection body through the other one of the plurality of leads 13; the control circuit 14 further obtains a first correction parameter based on the feedback signal, and adjusts the input impedance of the dropout detection circuit using the first correction parameter; wherein, drop detection circuit is connected with the lead.
In this embodiment, the control circuit 14 may control the switching circuit 81 to select any one of the leads as the input lead of the impedance detection signal and any other lead as the output lead of the feedback signal based on the actual detection requirement.
In this embodiment, for each lead, it may be used as both an input lead for an impedance detection signal in one application scenario and an output lead for a feedback signal in another application scenario.
And does not limit the number of input leads and output leads in the same application scenario.
Other circuit structures and operation principles of the present embodiment can be referred to the above embodiments.
The application further provides a lead falling-off detection circuit, as shown in fig. 4, and fig. 4 is a circuit schematic diagram of an embodiment of the lead falling-off detection circuit of the application. The lead falling off detection circuit of the present embodiment includes: the correction circuit 41 for lead drop detection and the drop detection circuit 42, wherein the correction circuit 41 for lead drop detection can refer to the embodiment of fig. 3, and the drop detection circuit 42 can refer to the embodiments of fig. 1 and 2, which are not described herein.
Wherein the drop detection circuit 42 is connected to the leads 12 and 13 for acquiring output signals of the leads 12 and 13, and is connected to the control circuit 15, and the control circuit 15 determines whether the leads 12 and 13 drop from the target detection body based on the output signals.
Separate dropout detection circuits 42 may be provided for the leads 12 and 13, respectively. In other embodiments, only the leads or leads may be subjected to dropout detection.
The application further provides an electrocardiograph monitoring circuit, as shown in fig. 5, and fig. 5 is a schematic circuit diagram of an embodiment of the electrocardiograph monitoring circuit of the application. The electrocardiograph monitoring circuit of the present embodiment includes a lead falling detection circuit 51 and a second filter circuit 52, where the second filter circuit 52 is respectively connected with the lead 13 and the control circuit 15, and is used for performing filtering processing on the feedback signal, so as to obtain an electrocardiograph signal of the target body from the feedback signal, and transmitting the electrocardiograph signal to the control circuit 15.
As can be seen from the above analysis, the feedback signal output by the lead 13 includes an impedance feedback signal and an electrocardiograph signal, wherein the impedance feedback signal is a high-frequency signal and the electrocardiograph signal is a low-frequency signal, so the second filter circuit 52 of the present embodiment is a low-pass filter circuit for filtering the high-frequency impedance feedback signal from the feedback signal to obtain the low-frequency electrocardiograph signal.
The lead drop detection circuit 51 may refer to the above embodiment, and is not described here.
Optionally, the electrocardiograph monitoring circuit of the present embodiment further includes a second gain circuit 53 connected to the control circuit 15 and the second filter circuit 52, where the control circuit 15 obtains a second correction parameter based on the impedance feedback signal and the input impedance in the feedback signal, and adjusts the gain of the second gain circuit based on the second correction parameter, so that the second gain circuit corrects the electrocardiograph signal.
When the magnitude of the pull-up resistor, the pull-down resistor, or the excitation current is adjusted, the input impedance of the lead dropout detection circuit 51, specifically, the input impedance of the dropout detection circuit, is affected. Due to the variation of the input impedance, a certain attenuation exists between the electrocardiograph signal obtained by the measurement circuit 14 and the real electrocardiograph signal, and the waveform attenuation of the electrocardiograph signal can be compensated by adjusting the gain of the second gain circuit 53 by the control circuit 15, so that a more accurate electrocardiograph signal can be obtained, and an equivalent effect of higher input impedance can be achieved.
Specifically, after determining the magnitudes of the pull-up resistor and the pull-down resistor (or the excitation current), the control circuit 15 can calculate the multiple of the waveform attenuation of the electrocardiograph signal (i.e., the second correction parameter) after testing the impedance value of the target detection body, thereby calculating the multiple of the electrocardiograph signal required to be amplified, adjusting the gain of the second gain circuit 53, adaptively adjusting the waveform amplitude of the electrocardiograph signal, and equivalently achieving the purpose of improving the input impedance to obtain a more accurate electrocardiograph waveform.
The application can be applied to electrocardiograph equipment, which can be electrocardiograph monitoring and diagnosis equipment. Such as an electrocardiograph, fetal heart monitor, etc.
The application further provides a lead falling off detection method, as shown in fig. 6, fig. 6 is a schematic flow chart of an embodiment of the lead falling off detection method of the application. The lead falling off detection method of the embodiment is used for the correction circuit, the lead falling off detection circuit and the electrocardio monitoring circuit for the lead falling off detection, and specifically comprises the following steps:
step S61: an impedance detection signal is transmitted to the target detection body through a lead.
The MCU generates a high-frequency square wave signal, the square wave signal generates a sine excitation signal with corresponding frequency through the sine wave generating circuit, namely a high-frequency sine wave signal, and the high-frequency sine wave signal is amplified through the excitation circuit to generate an impedance detection signal and is transmitted to the target detection body through the first lead.
Step S62: a feedback signal is received from the target test body via the second lead.
The target detector feeds back a feedback signal through the second lead.
Step S63: an impedance value of the target detection body is obtained based on the feedback signal.
Specifically, filtering the feedback signal to obtain an impedance feedback signal from the feedback signal; and calculating an impedance value corresponding to the impedance feedback signal through an impedance matrix algorithm.
The sine wave excitation signals form voltage drops under an equivalent impedance network of the target detection body, different voltage drop signals are obtained through the measuring circuit, the voltage drop signals are sent to the MCU through the ADC after being processed by the high-pass filter circuit and the like, the MCU obtains an impedance matrix through the filter algorithm, and then the impedance value of the target detection body is obtained through the impedance algorithm. The multi-path test can obtain the impedance values of different parts of the target detection body, the average impedance of the target detection body and other data.
Step S64: and acquiring a first correction parameter based on the impedance value, and adjusting the input impedance of the shedding detection circuit by using the first correction parameter.
After the MCU obtains the impedance value, a first correction parameter is obtained, and the resistance value (or the excitation current) of the pull-up resistor and the pull-down resistor of the drop-off detection circuit are adaptively adjusted by utilizing the first correction parameter, so that a better lead drop-off detection effect is obtained.
The application further provides a lead falling off detection method, as shown in fig. 7, fig. 7 is a schematic flow chart of an embodiment of the lead falling off detection method of the application. The lead falling off detection method of the embodiment is used for the correction circuit, the lead falling off detection circuit and the electrocardio monitoring circuit for the lead falling off detection, and specifically comprises the following steps:
step S71: an impedance detection signal is transmitted to the target detection body through a lead.
Step S72: a feedback signal is received from the target test body via the other lead.
Step S73: an impedance value of the target detection body is obtained based on the feedback signal.
Step S74: and acquiring a first correction parameter based on the impedance value, and adjusting the input impedance of the shedding detection circuit by using the first correction parameter.
The specific implementation of step S71 to step S74 may be referred to the above examples.
Step S75: the feedback signal is filtered to obtain an electrocardiosignal from the feedback signal.
And carrying out low-frequency filtering on the feedback signal to obtain a low-frequency electrocardiosignal.
Step S76: and determining a second correction parameter based on the adjusted input impedance and the impedance value.
Step S77: the gain on the electrocardiographic signal is adjusted based on the second correction parameter.
The control circuit obtains a second correction parameter based on the impedance feedback signal and the input impedance in the feedback signal, and adjusts the gain of the second gain circuit based on the second correction parameter so that the second gain circuit corrects the electrocardiosignal.
The input impedance of the dropout detection circuit may be affected when the magnitude of the pull-up resistor, the pull-down resistor, or the excitation current is adjusted. Due to the change of input impedance, a certain attenuation exists between the electrocardiosignals obtained by the measuring circuit and the real electrocardiosignals, and the waveform attenuation of the electrocardiosignals can be compensated by adjusting the gain of the second gain circuit by the control circuit, so that more accurate electrocardiosignals are obtained, and the equivalent effect of higher input impedance is achieved.
Compared with the prior art, the correction circuit for detecting the lead falling off of the application controls the detection signal generating circuit to generate an impedance detection signal through the control circuit, and transmits the impedance detection signal to the target detection body through a lead so as to carry out impedance detection on the target detection body; and then, outputting a feedback signal of the target detection body by using the other lead, transmitting the feedback signal to the control circuit by using the measuring circuit, acquiring a first correction parameter by using the control circuit based on the feedback signal, and adjusting the input impedance of the falling detection circuit by using the first correction parameter so as to improve the matching degree between the impedance of the target detection body and the input impedance of the falling detection circuit, so that the problem of false alarm caused by falling of the lead due to the fact that the pull-up resistance in the falling detection circuit is larger or the current of the excitation current is smaller in the prior art can be improved, and the problem of sensitivity reduction of falling detection of the lead due to the fact that the pull-up resistance in the falling detection circuit is larger or the current of the excitation current is smaller can be improved.
The foregoing description is only of embodiments of the present application, and is not intended to limit the scope of the application, and all equivalent mechanisms or equivalent flow path changes made by the present application and the accompanying drawings, or direct or indirect application in other related technical fields, are equally included in the scope of the present application.