CN113261971A - Suspension electrode automatic zero clearing circuit for non-contact electrocardiogram monitoring - Google Patents
Suspension electrode automatic zero clearing circuit for non-contact electrocardiogram monitoring Download PDFInfo
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- CN113261971A CN113261971A CN202110295644.8A CN202110295644A CN113261971A CN 113261971 A CN113261971 A CN 113261971A CN 202110295644 A CN202110295644 A CN 202110295644A CN 113261971 A CN113261971 A CN 113261971A
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Abstract
The invention discloses a suspension electrode automatic zero clearing circuit for non-contact electrocardiogram monitoring, which comprises a high-pass input stage circuit, an action interference suppression stage circuit and a switch zero clearing circuit, wherein the high-pass input stage circuit is connected with the action interference suppression stage circuit; the high-pass input-stage circuit comprises a suspension electrode, a low-bias current operational amplification circuit A1 and an active low-pass feedback module; the action interference suppression stage comprises an operational amplifier A3, a resistor R2 and a capacitor C2, and the output end of the action interference suppression stage is connected with a reference level pin REF of the operational amplifier A1; the switch zero clearing circuit comprises a positive phase comparator A4, an inverse phase comparator A5, a zero clearing switch S1 and a zero clearing switch S2; the output end of the operational amplifier A3 is connected with the non-inverting input end of the positive phase comparator A4 and the inverting input end of the inverting comparator A5; the output end of the positive phase comparator A4 is connected with the control end of the zero clearing switch S1, and the output end of the negative phase comparator A5 is connected with the control end of the zero clearing switch S2. When the output signal of the input stage of the measuring circuit is continuously saturated for a period of time, the automatic zero clearing can be carried out, and the continuous implementation of the electrocardio monitoring is ensured.
Description
[ technical field ] A method for producing a semiconductor device
The invention belongs to the technical field of electrocardio monitoring circuits, and particularly relates to an automatic suspension electrode zero clearing circuit for non-contact electrocardio monitoring.
[ background of the invention ]
The dynamic electrocardiogram is a clinical common cardiovascular disease screening means, and by recording continuous electrocardiosignals of a suspicious patient for more than 24 hours in a natural living state, arrhythmia events and ST segment abnormal changes which are difficult to find by the conventional electrocardiogram are found, so that an important diagnosis evaluation basis is obtained. The electrocardiosignal acquisition electrodes used in the traditional electrocardio measurement are Ag/AgCl wet electrodes with conductive adhesive, the skin of the wet electrodes needs to be cleaned by alcohol before use, the electrodes are tightly attached to the skin of a human body, the electrocardiosignal acquisition electrodes are not suitable for people with skin allergy, can not be repeatedly used, are not suitable for long-term dynamic monitoring of electrocardiosignals of the human body, and have high cost for long-term monitoring. The non-contact electrocardio monitoring avoids many problems of the traditional lead contact type, especially the wearing comfort and the applicability. The non-contact electrocardio monitoring is a novel wearable and continuous electrocardio monitoring method, and a non-contact electrocardio monitoring circuit mostly adopts a suspension electrode to carry out induction type measurement on electrocardiosignals, and the suspension electrode and an electrocardiosignal source form a capacitor to carry out alternating current coupling on the electrocardiosignals to a measuring circuit. The floating electrode is generally connected to the input end of the measuring circuit through a high-resistance path, under the influence of bias current, the potential of the floating electrode can accumulate larger drift after the measuring circuit works for a period of time, and when the drift exceeds the common-mode voltage range of the measuring circuit, the measuring circuit is saturated or cut off, and the electrocardio monitoring is forced to stop.
At present, most circuits adopt a relatively simple zero clearing method, namely a zero clearing switch is controlled by the output voltage of a measuring circuit, and if output is saturated, the switch is turned on to clear the voltage accumulated by drifting of a suspended electrode. On one hand, the method is not good for automation, on the other hand, in the electrocardio monitoring process, instantaneous output saturation can occur due to the action of the output voltage along with the human body, so that the suspended electrode is cleared frequently, the monitoring of a cardiac cycle can be sacrificed once in the clearing process, and the frequent clearing mode is not good for continuous monitoring.
Therefore, there is a need to provide a new automatic floating electrode zero clearing circuit for non-contact electrocardiographic monitoring to solve the above technical problems.
[ summary of the invention ]
The invention mainly aims to provide a suspension electrode automatic zero clearing circuit for non-contact electrocardiogram monitoring, which can automatically clear when an input-stage output signal of a measuring circuit is continuously saturated for a period of time, so as to ensure the continuous implementation of electrocardiogram monitoring.
The invention realizes the purpose through the following technical scheme: a suspension electrode automatic zero clearing circuit for non-contact electrocardiogram monitoring comprises a high-pass input stage circuit, an action interference suppression stage circuit and a switch zero clearing circuit;
the high-pass input stage circuit comprises a suspension electrode, a low bias current operational amplification circuit A1 and an active low-pass feedback module;
the action interference suppression stage circuit is an inverting integrating circuit and comprises an operational amplifier A3, a resistor R2 and a capacitor C2, and the output end of the action interference suppression stage circuit is connected with a reference level pin REF of the low-bias current operational amplification circuit A1;
the switch zero clearing circuit comprises a positive phase comparator A4, an inverse phase comparator A5, a zero clearing switch S1 and a zero clearing switch S2;
the output end of the operational amplifier A3 is respectively connected with the non-inverting input end of the positive phase comparator A4 and the inverting input end of the inverting comparator A5; the output end of the positive phase comparator A4 is connected with the control end of the zero clearing switch S1, and the output end of the negative phase comparator A5 is connected with the control end of the zero clearing switch S2.
Further, the active low-pass feedback module includes a low-bias current operational amplifier a2, a resistor R1, and a capacitor C1, and the floating electrode is divided into two paths and respectively connected to the non-inverting input terminal of the low-bias current operational amplifier circuit a1 and the non-inverting input terminal of the low-bias current operational amplifier circuit a 2.
Further, the output end of the low bias current operational amplifier A2 is electrically connected with the inverting input end; one end of the resistor R1 is connected with the output end of the low bias current operational amplifier A2, and the other end is respectively connected with the inverting input end of the low bias current operational amplifier circuit A1 and the capacitor C1; the other end of the capacitor C1 is grounded.
Further, the output end of the low-bias current operational amplifier circuit a1 is connected to the inverting input end of the operational amplifier A3, and the resistor R2 is disposed on the connection line; the capacitor C2 has one end connected to the inverting input end of the operational amplifier A3 and the other end connected to the output end of the operational amplifier A3; the same-direction input end of the operational amplifier A3 is grounded, and the output end is connected to the reference level pin REF of the low-bias current operational amplification circuit A1.
Further, one end of each of the zero clearing switch S1 and the zero clearing switch S2 is connected to the non-inverting input terminal of the low bias current operational amplifier circuit a 1; the inverting input end of the positive phase comparator A4 inputs a positive threshold voltage Vh +; the non-inverting input terminal of the inverting comparator A5 inputs a negative threshold voltage Vh-.
Further, the other ends of the clear switch S1 and the clear switch S2 are grounded.
Compared with the prior art, the suspension electrode automatic zero clearing circuit for non-contact electrocardiogram monitoring has the advantages that: after the output signal of the input stage of the measuring circuit is continuously saturated for a period of time, automatic zero clearing can be carried out, and continuous electrocardio monitoring is guaranteed. The output signal is adopted to control the zero clearing action of the suspension electrode, and the type of the output signal exceeding the limit needs to be distinguished. The signal jitter generated by human body action can be effectively discriminated, unnecessary zero clearing is avoided, and continuous monitoring of the electrocardiosignal is ensured while human body action interference is inhibited; for the condition that the potential of the suspended electrode exceeds the common-mode voltage range, the scheme can effectively discriminate, realize automatic and quick zero clearing and ensure the long-term stable work of the circuit.
[ description of the drawings ]
Fig. 1 is a schematic structural diagram of an embodiment of the present invention.
[ detailed description ] embodiments
The first embodiment is as follows:
referring to fig. 1, the present embodiment is a floating electrode auto-zero circuit 100 for non-contact electrocardiographic monitoring, which includes a high-pass input stage circuit 1, an operation interference suppression stage circuit 2, and a switch zero-clearing circuit 3.
The high-pass input stage circuit 1 comprises a floating electrode 11, a low-bias current operational amplification circuit A1 and an active low-pass feedback module. The active low-pass feedback module comprises a low-bias current operational amplifier A2, a resistor R1 and a capacitor C1, and the suspension electrode 11 is divided into two paths which are respectively connected with the non-inverting input end of the low-bias current operational amplifier circuit A1 and the non-inverting input end of the low-bias current operational amplifier circuit A2. The output end of the low bias current operational amplifier A2 is electrically connected with the inverting input end; one end of the resistor R1 is connected with the output end of the low bias current operational amplifier A2, and the other end of the resistor R1 is respectively connected with the inverting input end of the low bias current operational amplifier circuit A1 and the capacitor C1; the other terminal of the capacitor C1 is connected to ground. The output end of the active low-pass feedback module is formed between the resistor R1 and the capacitor C1 and is connected to the inverting input end of the low-bias current operational amplification circuit A1. The low bias current operational amplifier A2, the resistor R1 and the capacitor C1 form low pass filtering, the output of the low bias current operational amplifier enters a low bias current operational amplifier circuit A1, is subtracted from the electrocardiosignals collected by the suspension electrode 11, and is subjected to differential amplification in a low bias current operational amplifier circuit A1, so that a high pass effect is realized, and the typical value of the low pass cut-off frequency is 0.1 Hz-1 Hz.
The operation interference suppression stage circuit 2 is an inverting integrator circuit, and the output terminal thereof is connected to the reference level pin REF of the low bias current operational amplifier circuit a 1. The operation interference suppression stage circuit 2 includes an operational amplifier a3, a resistor R2, and a capacitor C2. The output end of the low bias current operational amplification circuit A1 is connected to the inverting input end of the operational amplifier A3, and the resistor R2 is arranged on the connecting line; one end of the capacitor C2 is connected to the inverting input end of the operational amplifier A3, and the other end is connected to the output end of the operational amplifier A3; the non-inverting input terminal of the operational amplifier A3 is grounded, and the output terminal is connected to the reference level pin REF of the low bias current operational amplifier circuit A1. The low bias current operational amplifier circuit A1 adopts a differential amplification structure, mainly realizes two functions, one is to realize low bias current, the other is to have a fixed gain with a gain of 10-100 times, a plurality of amplifiers can be adopted to form an instrument amplifier circuit structure, and a single-chip instrument amplifier can also be adopted to realize the operation. The bias currents of the low bias current operational amplifier circuit a1 and the low bias current operational amplifier a2 are 10fA to 90 fA.
The switch zero clearing circuit 3 comprises a positive phase comparator A4, an inverse phase comparator A5, a zero clearing switch S1 and a zero clearing switch S2, wherein the output end of an operational amplifier A3 in the inverse phase integrating circuit is connected with the non-inverting input end of a positive phase comparator A4 and the inverting input end of an inverse phase comparator A5; the output of the positive phase comparator A4 is connected with the control end of the zero clearing switch S1, the output of the negative phase comparator A5 is connected with the control end of the zero clearing switch S2, and one ends of the zero clearing switch S1 and the zero clearing switch S2 are both connected with the non-inverting input end of the low bias current operational amplification circuit A1; the inverting input terminal of the positive phase comparator A4 inputs a positive threshold voltage Vh +; the non-inverting input terminal of the inverting comparator a5 inputs a negative threshold voltage Vh-. The other ends of the clear switch S1 and the clear switch S2 are grounded.
When the potential of the suspended electrode 11 exceeds the positive upper limit of the common-mode voltage of the low-bias-current operational amplification circuit A1, the output of the low-bias-current operational amplification circuit A1 is continuously saturated in the positive direction, the capacitor C2 is continuously integrated, when the output of the operational amplifier A3 is lower than the negative threshold voltage Vh-, the output of the inverting comparator A5 is connected with the zero clearing switch S2, the suspended electrode 11 is cleared through the zero clearing switch S2, the instantaneous output of the low-bias-current operational amplification circuit A1 is zero, the capacitor C2 discharges, the output of the operational amplifier A3 is higher than Vh-, the zero clearing switch S2 is disconnected, the suspended electrode is cleared completely, and the electrocardio induction signal is continuously monitored.
When the potential of the suspended electrode 11 exceeds the negative upper limit of the common-mode voltage of the low-bias current operational amplification circuit A1, the output of the low-bias current operational amplification circuit A1 is continuously saturated in the negative direction, the capacitor C2 is continuously integrated, when the output of the operational amplifier A3 is higher than the positive threshold voltage Vh +, the output of the positive-phase comparator A4 is connected with the zero clearing switch S1, the suspended electrode 11 is cleared through the zero clearing switch S1, the instantaneous output of the low-bias current operational amplification circuit A1 is zero, the capacitor C2 discharges, the output of the operational amplifier A3 is lower than Vh +, the zero clearing switch S1 is disconnected, the suspended electrode 11 is cleared completely, and the electrocardio induction signal is continuously monitored.
For jitter interference signals causing abnormity of human body actions, the jitter signals superposed in the electrocardiosignals can enable the output of the high-pass input stage circuit 1 to rapidly increase in positive phase or negative phase, the output voltage of the corresponding action interference suppression stage circuit 2 can rapidly increase in negative phase or positive phase, and the output of the action interference suppression stage circuit 2 is fed back to the high-resistance amplifier A1 to serve as a reference voltage, so that the output of the high-pass input stage circuit 1 tends to be stable, and the interference of the jitter signals on the electrocardiosignals caused by abnormity of human body actions is suppressed; therefore, the potential of the suspended electrode 11 does not exceed the common-mode voltage range, and further, the zero clearing action cannot be triggered due to the shaking generated by the human body action, so that the effective and continuous electrocardio monitoring is guaranteed.
In the automatic floating electrode zero clearing circuit 100 for non-contact electrocardiographic monitoring of the present embodiment, the output signal is used to control the zero clearing operation of the floating electrode, and the type of the output signal exceeding the limit needs to be distinguished. The signal jitter generated by human body action can be effectively discriminated, unnecessary zero clearing is avoided, and continuous monitoring of the electrocardiosignal is ensured while human body action interference is inhibited; for the condition that the potential of the suspended electrode exceeds the common-mode voltage range, the scheme can effectively discriminate, realize automatic and quick zero clearing and ensure the long-term stable work of the circuit.
What has been described above are merely some embodiments of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the inventive concept thereof, and these changes and modifications can be made without departing from the spirit and scope of the invention.
Claims (6)
1. The utility model provides a suspension electrode automatic zero clearing circuit for non-contact electrocardio monitoring which characterized in that: the circuit comprises a high-pass input stage circuit, an action interference suppression stage circuit and a switch zero clearing circuit;
the high-pass input stage circuit comprises a suspension electrode, a low bias current operational amplification circuit A1 and an active low-pass feedback module;
the action interference suppression stage circuit is an inverting integrating circuit and comprises an operational amplifier A3, a resistor R2 and a capacitor C2, and the output end of the action interference suppression stage circuit is connected with a reference level pin REF of the low-bias current operational amplification circuit A1;
the switch zero clearing circuit comprises a positive phase comparator A4, an inverse phase comparator A5, a zero clearing switch S1 and a zero clearing switch S2;
the output end of the operational amplifier A3 is respectively connected with the non-inverting input end of the positive phase comparator A4 and the inverting input end of the inverting comparator A5; the output end of the positive phase comparator A4 is connected with the control end of the zero clearing switch S1, and the output end of the negative phase comparator A5 is connected with the control end of the zero clearing switch S2.
2. The suspended electrode auto-zero circuit for non-contact electrocardiographic monitoring according to claim 1, wherein: the active low-pass feedback module comprises a low-bias current operational amplifier A2, a resistor R1 and a capacitor C1, and the suspension electrode is divided into two paths which are respectively connected with the non-inverting input end of the low-bias current operational amplifier A1 and the non-inverting input end of the low-bias current operational amplifier A2.
3. The suspended electrode auto-zero circuit for non-contact electrocardiographic monitoring according to claim 2, wherein: the output end of the low bias current operational amplifier A2 is electrically connected with the inverting input end; one end of the resistor R1 is connected with the output end of the low bias current operational amplifier A2, and the other end is respectively connected with the inverting input end of the low bias current operational amplifier circuit A1 and the capacitor C1; the other end of the capacitor C1 is grounded.
4. The suspended electrode auto-zero circuit for non-contact electrocardiographic monitoring according to claim 1, wherein: the output end of the low-bias current operational amplification circuit A1 is connected to the inverting input end of the operational amplifier A3, and the resistor R2 is arranged on the connecting line; the capacitor C2 has one end connected to the inverting input end of the operational amplifier A3 and the other end connected to the output end of the operational amplifier A3; the same-direction input end of the operational amplifier A3 is grounded, and the output end is connected to the reference level pin REF of the low-bias current operational amplification circuit A1.
5. The suspended electrode auto-zero circuit for non-contact electrocardiographic monitoring according to claim 1, wherein: one end of each of the zero clearing switch S1 and the zero clearing switch S2 is connected to the non-inverting input end of the low bias current operational amplification circuit A1; the inverting input end of the positive phase comparator A4 inputs a positive threshold voltage Vh +; the non-inverting input terminal of the inverting comparator A5 inputs a negative threshold voltage Vh-.
6. The suspended electrode auto-zero circuit for non-contact electrocardiographic monitoring according to claim 5, wherein: the other ends of the zero switch S1 and the zero switch S2 are grounded.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110295644.8A CN113261971A (en) | 2021-03-19 | 2021-03-19 | Suspension electrode automatic zero clearing circuit for non-contact electrocardiogram monitoring |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110295644.8A CN113261971A (en) | 2021-03-19 | 2021-03-19 | Suspension electrode automatic zero clearing circuit for non-contact electrocardiogram monitoring |
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| CN113261971A true CN113261971A (en) | 2021-08-17 |
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| CN202110295644.8A Pending CN113261971A (en) | 2021-03-19 | 2021-03-19 | Suspension electrode automatic zero clearing circuit for non-contact electrocardiogram monitoring |
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- 2021-03-19 CN CN202110295644.8A patent/CN113261971A/en active Pending
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