KR101007818B1 - Non-contact heartbeat sensor and heartbeat signal processing method using the same - Google Patents

Abstract

Non-contact heart rate measuring sensor that can measure high quality heart rate signal by measuring heart rate signal without direct contact with the body skin of the subject and preventing the measured heart rate signal from interfering with ambient noise and using the same A signal processing method is disclosed. To this end, there is provided a non-contact heart rate measurement sensor including an electrode unit, an LC oscillator, an inverter, a phase synchronization circuit, a buffer, an RC low pass filter, and an amplifier, and a signal processing method using the same. By using the non-contact heart rate measuring sensor and the signal processing method using the same according to the present invention, there is no direct contact of the skin of the body can be measured without the subject is not aware of the heart rate measurement, by removing the interference noise from the surroundings The advantage is that quality and accurate heart rate can be measured.

Description

Non-contact heart rate measuring sensor and signal processing method using same {NON-CONTACT HEARTBEAT SENSOR AND HEARTBEAT SIGNAL PROCESSING METHOD USING THE SAME}

The present invention relates to a heart rate measuring sensor and a signal processing method, and more particularly, to a non-contact heart rate measuring sensor and a signal processing method using the same, which can measure a heart rate signal without contacting electrodes with body skin.

Electrocardiogram, called ECG (ElectroCardioGram), is a record of the active current generated by the contraction and expansion of the heart muscle due to the beating of the heart.The current data measured after measuring the active current according to the contraction of the heart muscle by attaching electrodes to the body skin. To describe the graph.

More specifically, the action potential generated when the heart muscle contracts and relaxes causes an electric current spreading from the heart to the whole body, and this electric current generates an electric potential difference according to the position of the body, which is detected by the surface electrode attached to the human skin. Can be recorded.

The electrocardiogram is that the electric potential generated by the electrical excitement that occurs when the heart muscle is active (heartbeat) is transmitted to the surface of the body and then recorded as a waveform by electric current, and heart disease such as angina, myocardial infarction and arrhythmia This is a very important way to diagnose this problem.

The electrocardiogram is a representative bioelectric signal along with the EMG, EEG and bioimpedance signals, which is the most basic signal for diagnosing the health state of the subject by non-invasive methods, and the electrocardiogram is the basic biosignal along with the respiration signal. It is widely used in clinical practice.

In the medical field for measuring biopotential such as electrocardiogram, electrocardiogram, and electroencephalogram for proper treatment, diagnostic methods for proper treatment are being developed by sending electrical signals to the external device.

Electrode induction is a method of measuring the vital signs of the heart, which is currently widely used.

Electrode induction is a method of measuring the biopotential generated when the electrical stimulation generated in the eastern crystal of the heart is conducted to the left and right ventricles and the left and right atria.

As such, the limb electrode induction method and the two-electrode measurement method are mainly used as the measurement method using the electrode.

The limb electrode induction method can measure the electric potential as the length of the shipment is longer electromagnetically, attaching electrodes to both arms and legs of the human body and connecting it to the cardiac electrical activity measuring device to measure the electrical activity of the heart. It is a way. In the case of the limb electrode induction method, the longer the path of the shipment, the shorter the size and the more difficult to measure due to the characteristic that can measure the large potential has the disadvantage that it is sensitive to noise.

In addition, the two-electrode measuring method is a method of measuring the electrical activity of the heart by attaching an electrode to the chest area using an elastic band. In the case of the two-electrode measurement method, there is a problem in that it is difficult to wear the elastic band for a long time because of the feeling of pressure on the chest. In addition, there is a problem in that the quality of the heart rate signal measured when the electrode is loosely attached due to a user's mistake when the first attachment or the humidity of the electrode is reduced due to long use.

The ECG methods mentioned above may cause damage to the skin of the body, and there is a problem that normal ECG measurement is difficult because the subject becomes aware of ECG by applying pressure on a part of the body.

In order to solve these problems, a heart rate measurement technology has been developed that enables a high quality electrocardiogram measurement by preventing a subject from being conscious of heart rate measurement by not making direct contact with body skin.

For example, a method of directly detecting an electrocardiogram signal through a capacitance between the skin and an electrode with a cloth interposed therebetween, and a method of measuring a heartbeat using a Doppler radar.

However, in the case of measuring electrocardiogram through the capacitance between the electrodes, there is a problem that a high performance instrumentation amplifier and impedance matching are required, and in the case of the heart rate measurement method using a Doppler radar, radio waves are directly incident on the body. There is a problem that may be accompanied by the side effects of the body, and also there is a problem that the cost of using expensive high-frequency components is increased.

You can also use a stethoscope or microphone to measure your heartbeat. In this case, there is a problem that it is difficult to measure a high quality heartbeat sound when the surroundings are a little disturbed because it is very sensitive to ambient noise.

Accordingly, there is a need for the development of an electrocardiogram measuring method that can solve the problems arising from various methods for measuring the conventional heart rate. That is, the development of a heart rate measurement method capable of measuring heart rate information (signal) without direct contact with the body and without interference from ambient noise is required.

Therefore, the first object of the present invention is to measure the heart rate signal without direct contact with the body skin of the subject, as well as to ensure that the measured heart rate signal is not interfered with by ambient noise, thereby measuring a high quality heart rate signal. To provide a non-contact heart rate measurement sensor.

It is a second object of the present invention to provide a heartbeat signal processing method using a contactless heartbeat lateral sensor capable of measuring heartbeat without direct contact with body skin.

In order to achieve the first object of the present invention described above, the present invention is an electrode unit that is charged with electrical capacity due to heart rate; An LC oscillator for oscillating a biosignal due to a heartbeat according to an electrical capacitance charged by the electrode portion; An inverter for converting the oscillated frequency signal outputted through the LC oscillator into a square wave signal known to the machine; A phase synchronization circuit configured to synchronize the phase of the biosignal converted through the inverter so that the converted biosignal output through the inverter is not changed by ambient noise; A buffer for buffering the biosignal output through the phase synchronization circuit; An RC low pass filter filtering the biosignal output through the buffer; And an amplifier for amplifying the biosignal filtered through the RC low pass filter.

In addition, in order to achieve the second object of the present invention, the present invention comprises the steps of measuring the bio-signal due to the heart rate through the electrode unit and the LC oscillator; Converting the measured heart rate biosignal into a square wave that a machine can know through an inverter; Synchronizing the phase of the biosignal converted into the square wave through a phase synchronization circuit; Buffering the phase-locked biosignal; Filtering the buffered biosignal; And it provides a signal processing method using a non-contact heart rate measurement sensor comprising amplifying the filtered bio-signal.

Using the non-contact heart rate measurement sensor and the signal processing method using the same according to the present invention, there is no direct contact of the skin of the body can be measured in a state in which the subject is not aware of the heart rate measurement to measure a higher quality and accurate heart rate The advantage is that you can.

In addition, by removing the noise that interferes with the surroundings, there is an advantage that a higher quality accurate heart rate can be measured.

As such, the more accurate heart rhythm can be measured, thereby providing more accurate medical treatment for the heart disease of the examinee.

In addition, by measuring the heartbeat signal in a non-contact manner, there is no need for a separate operation for measuring the heartbeat signal can be used by a medical practitioner lacking in skill can be expected to improve the ease of use.

Hereinafter, a non-contact heart rate measuring sensor and a signal processing method using the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Heart rhythm means repetitive movement of the heart's contraction and expansion.

In other words, the heart acts like a pump, which contracts periodically to push blood into the arteries, relaxes and fills the lumen with blood coming from the veins. At this time, opening and closing of the valve in order to prevent the back flow of blood, the pump action is repeated smoothly, thereby circulating blood throughout the body. This repetition of the contraction and expansion of the heart is called rhythm.

Like this, the heart, which repeatedly contracts and expands, has a certain pattern, and the heart beats by measuring a certain pattern of the heartbeat.

However, since the heartbeat signal (biosignal) is a minute signal with a very small frequency band, not a signal that can be heard by the general public, the risk of interference from surrounding noise is high.

In other words, since the heartbeat biosignal is a very fine signal, it is difficult to measure the heartbeat biosignal as it is interfered by ambient invisible noise (called white noise).

The white noise is a noise that can be heard when the sound is the same at all frequencies existing in the human audible frequency band. The white noise causes noise in the heart rate signal measured by the white noise to measure a high quality heart rate signal. Is difficult.

Accordingly, the present invention measures a heart rate signal that is very susceptible to interference from surrounding white noise due to a very small signal, thereby measuring a heart rate signal of a desired frequency band (for example, a frequency band within 0.3 to 20 Hz, In one embodiment, the present invention relates to a technique for removing frequencies of the remaining region except for a heart rate signal corresponding to a frequency of 30 Hz or less).

The present invention further relates to a technique capable of measuring heart rate signals without direct contact with body skin.

First, the present invention provides a non-contact heart rate measuring sensor.

1 is a schematic block diagram illustrating a non-contact heart rate measuring sensor according to an embodiment of the present invention.

Referring to FIG. 1, a non-contact heart rate measuring sensor according to an embodiment of the present invention includes an electrode part 100 and an LC oscillator 110.

The electrode unit 100 is charged with an electrical capacity due to the heartbeat.

To this end, the electrode unit 100 is preferably composed of two metals, for example, and thus the capacitance is present between the two metals, the value of the capacitance between the two metals is the distance between the metals or the dielectric constant of the metal surrounding material Will be decided by.

That is, the electrode unit 100 is not attached directly to the chest where the heart to be measured is positioned in a non-contact manner to charge the electrical capacity due to the heartbeat. However, as the electrode part 100 is positioned closer to the chest where the heart is located, more accurate heart rate signal may be measured.

In addition, the LC oscillator 110 plays a role of oscillating a biosignal due to a heartbeat according to the electrical capacitance charged from the electrode unit 100.

The LC oscillator 110 is used as a resonator to induce a waveform or vibration of a specific frequency by using a resonance phenomenon, and as the inductance (L) of the coil and the capacitance (electric capacitance) (C) of the capacitor (capacitor). A sinusoidal AC oscillator using a resonance circuit formed as a frequency determining element.

Accordingly, the LC oscillator 110 oscillates a biosignal according to the electrical capacitance C charged from the electrode unit 110.

2 is a circuit diagram illustrating an LC oscillator and an inverter for explaining a non-contact heart rate measuring sensor according to an embodiment of the present invention.

2, the non-contact heart rate measuring sensor according to an embodiment of the present invention is preferably designed such that the electrical capacitance charged through the electrode unit 100 is input to Q ₂ .

로 결정된다. 즉, 상기 생체 신호(f)는 L3, C10, 및 C11에 의해 결정되고, 상기

에 의해 결정될 것이다.And a biosignal output through the LC oscillator 110.

Is determined. That is, the biosignal f is determined by L3, C10, and C11, and

Will be decided by.

Accordingly, the frequency of the biosignal will be output by the result of the electrical capacitance of the electrode unit 100 input to the LC oscillator 110 (Q ₂ ) added to C ₁₁ .

3 is a view showing a waveform output through the LC oscillator for explaining the non-contact heart rate measurement sensor according to an embodiment of the present invention.

Referring to FIG. 3, the frequency of the biosignal output through the LC oscillator 110 was measured to have a amplitude of 1.09 MHz and an amplitude of 4.52 V _PP .

Referring to FIG. 1, a non-contact heart rate measuring sensor according to an embodiment of the present invention includes an inverter 120.

The inverter 120 receives an oscillated frequency signal output through the LC oscillator 110 and converts the oscillated frequency signal into a mechanical square wave signal that can be known by a machine.

In more detail, the inverter 120 divides the heartbeat of a person having a certain pattern measured by the LC oscillator 110 into a square wave signal by dividing it into a logic frequency for each cycle.

Referring to FIG. 2, the inverter 120 may be designed to be connected to an output terminal of the LC oscillator 110.

4 is a view showing a waveform of a biosignal input to an inverter for explaining a non-contact heart rate measuring sensor according to an embodiment of the present invention, Figure 5 is a non-contact heart rate measuring sensor according to an embodiment of the present invention It is a figure which shows the output waveform which passed the inverter for demonstrating.

4 and 5, it can be seen that the waveform A input from the LC oscillator 110 changes to a square wave through the inverter 120 (B).

The inverter 120 may lower the center frequency such that the biosignal frequency due to the heartbeat input to the inverter 120 through the LC oscillator 110 has a waveform between 0 and 3V.

Referring to FIG. 1, a non-contact heart rate measuring sensor according to an embodiment of the present invention includes a phase synchronization circuit 130.

The phase locked circuit (PLL) 130 receives the converted biosignal output through the inverter 120 and converts the biosignal received through the inverter 120 so that the input biosignal is not changed by ambient noise. And to synchronize the phase of the biosignal.

In more detail, the electrical capacity (capacitance) of the electrode unit 100 is changed due to a change in the position of the electrode unit 100 or the surrounding environment, and the like. The frequency of the LC oscillator 110 in which the oscillation of the signal is determined is changed.

As a result, the frequency of the LC oscillator 110 changes and the voltage changes as the frequency changes. In this case, the variable resistance of the phase synchronization circuit 130 is changed to be external to the biosignal output through the inverter 120. It would be desirable to synchronize the voltage so that noise interference would not occur.

In addition, as a method for more effectively removing noise of the biosignal output through the phase synchronization circuit 130, the capacitor may be further designed adjacent to the VDD input pin.

In other words, when the reference voltage is increased to a desired voltage, noises below the desired reference voltage disappear and a cleaner signal can be output.

6 is a circuit diagram illustrating a phase synchronization circuit for explaining a non-contact heart rate measuring sensor according to an embodiment of the present invention, Figure 7 is an electrode for explaining a non-contact heart rate measuring sensor according to an embodiment of the present invention The figure shows the voltage output through the phase synchronization circuit when the person is not located in front and when the heart is located.

Referring to FIG. 6, it is preferable that the inverter 120 is designed to be connected to a terminal for outputting a biosignal.

In addition, referring to FIG. 7, the voltage outputted through the phase synchronization circuit 130 may be checked. More specifically, before the electrode unit 100 is located at the heart position where the body skin, that is, the heart rate at which the heart rate can be measured (a) and at the heart position (b), the output of each voltage can be checked. have.

When there is nothing in front of the electrode unit 100, the voltage output through the phase synchronization circuit 130 was measured to be 2.9V, and when the electrode unit 100 is located at the heart position, the phase synchronization circuit 130 You can see that the output voltage drops to 2.0V.

Referring to FIG. 1, the non-contact heart rate measuring sensor according to an embodiment of the present invention includes a buffer 140.

The buffer 140 serves to buffer the biosignal output through the phase synchronization circuit 130. That is, the buffer 140 allows the signal output from the phase synchronization circuit 130 to be input to the RC low pass filter 150 as it is without being interrupted by noise.

In more detail, the biosignal output through the phase synchronization circuit 130 may be subjected to noise interference by the voltage of the circuit, and may also be interfered with by external noise. Accordingly, the biosignal output through the phase synchronization circuit 130 may be input to the RC low pass filter 150 without being subjected to noise interference.

8 is a circuit diagram illustrating a buffer for explaining a non-contact heart rate measurement sensor according to an embodiment of the present invention.

Referring to FIG. 8, the buffer 140 is preferably connected to a terminal output through the phase synchronization circuit 130.

Referring to FIG. 1, a non-contact heart rate measuring sensor according to an embodiment of the present invention includes an RC low pass filter 150.

The RC low pass filter (LPF) 150 filters the biosignal output through the buffer 140.

More specifically, the biosignal output through the buffer 140 is a heartbeat signal in which the frequency of the measured biosignal is measured as it is so as not to interfere with external noise from the frequency of the biosignal generated by the heartbeat.

The heart rate signal thus measured is passed through the RC low pass filter 150 only a signal below a desired specific frequency.

RC low pass filter 150 of the present invention is preferably to pass only a frequency signal of 30kHz or less as an example.

9 is a circuit diagram illustrating an RC low pass filter for explaining a non-contact heart rate measuring sensor according to an embodiment of the present invention.

9, it is designed to be connected to the output terminal of the buffer 140 so that only frequency signals of 30 kHz or less of the bio signals output through the buffer 140 are passed.

FIG. 10 is a diagram illustrating a biosignal that passes through a buffer for explaining a contactless heartbeat measurement sensor according to an embodiment of the present invention, and FIG. 11 is a view illustrating a contactless heartbeat measurement sensor according to an embodiment of the present invention. A diagram showing a biosignal that has passed through a buffer for the present invention.

Referring to FIGS. 10 and 11, after the biological signal, in which the 625 kHz noise that is output from the buffer 140 and the input (D) is not removed, passes through the RC low pass filter 150, the noise is reduced. It can be seen that the removed clean bio signal is output.

Referring to FIG. 1, the non-contact heart rate measuring sensor according to an embodiment of the present invention includes an amplifier 160.

The amplifier 160 serves to amplify the biosignal filtered through the RC low pass filter 150.

In more detail, the biosignal filtered and output through the RC lowpass filter 150 is a biosignal frequency signal that passes through the RC lowpass filter 150 among the frequencies of the biosignals generated by the heartbeat. The biosignal frequency is a very fine signal that is not audible to the human ear. This minute signal is amplified to the size of the signal that can be heard by the amplifier 160.

In one embodiment of the present invention, the amplifier 160 may be amplified by 15 to 25 times the biological signal filtered through the RC low pass filter 150.

12 is a circuit diagram illustrating an amplifier for explaining a non-contact heart rate measurement sensor according to an embodiment of the present invention.

Referring to FIG. 12, the amplifier 160 may be designed to be connected to an output terminal of the RC low pass filter 150. The designed amplifier 160 is designed as an amplifier capable of 24 times amplification. As mentioned above, the amplifier 160 may be designed to enable amplification of 15 to 25 times according to the characteristics of an analog to digital converter (ADC). This will allow the selective design of the amplification ratio depending on the initial design purpose.

13 is a circuit diagram illustrating a ground for explaining a non-contact heart rate measuring sensor according to an embodiment of the present invention, Figure 14 is a power supply for explaining a non-contact heart rate measuring sensor according to an embodiment of the present invention. It is a circuit diagram.

13 and 14, the non-contact heart rate measuring sensor according to an embodiment of the present invention preferably includes a ground and a power supply.

The ground and the power supply unit serve to drive the non-contact heart rate measuring sensor according to the present invention.

In addition, the ground is preferably designed so that the non-contact heart rate measuring sensor of the present invention is located on the outside of the sensor by attaching an electrode to the output for normal operation. Furthermore, it may be desirable to design shielding so that it is not affected by the movement of external objects.

And the present invention provides a signal processing method using a contactless heart rate measurement sensor. Hereinafter, descriptions of parts common to those of the above-described non-contact heart rate measuring sensor will be omitted or abbreviated.

15 is a schematic flowchart illustrating a signal processing method using a non-contact heart rate measurement sensor according to an embodiment of the present invention.

Referring to Figure 15, the step of measuring the bio-signal by the heart rate (S100); Converting the measured heart rate biosignal into a square wave known by a machine through an inverter (S200); Synchronizing with the phase of the biosignal converted into the square wave through a phase synchronization circuit (S300); Buffering the phase-synchronized biosignal (S400); Filtering the buffered biosignal (S500); And amplifying the filtered biosignal (S600).

In step S100, the biosignal may be measured by heartbeat through the electrode unit and the LC oscillator.

In step S500, it is preferable to allow only a biological signal of a frequency band of 30 Hz or less to pass therethrough.

In step S600, the frequency of the biosignal having passed through step S500 may be amplified 15 to 25 times.

While the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

1 is a schematic block diagram illustrating a non-contact heart rate measuring sensor according to an embodiment of the present invention.

2 is a circuit diagram illustrating an LC oscillator and an inverter for explaining a non-contact heart rate measuring sensor according to an embodiment of the present invention.

3 is a view showing a waveform output through the LC oscillator for explaining the non-contact heart rate measurement sensor according to an embodiment of the present invention.

4 is a view showing a waveform of a biosignal input to an inverter for explaining a non-contact heart rate measuring sensor according to an embodiment of the present invention.

5 is a view showing an output waveform passing through the inverter for explaining the non-contact heart rate measurement sensor according to an embodiment of the present invention.

6 is a circuit diagram showing a phase synchronization circuit for explaining a non-contact heart rate measurement sensor according to an embodiment of the present invention.

FIG. 7 is a diagram illustrating voltages output through a phase synchronization circuit when a person is not positioned and a heart is positioned in front of an electrode for explaining a non-contact heart rate measuring sensor according to an embodiment of the present invention.

8 is a circuit diagram illustrating a buffer for explaining a non-contact heart rate measurement sensor according to an embodiment of the present invention.

9 is a circuit diagram illustrating an RC low pass filter for explaining a non-contact heart rate measuring sensor according to an embodiment of the present invention.

FIG. 10 is a diagram illustrating a biosignal that passes through a buffer for explaining a non-contact heart rate measuring sensor according to an exemplary embodiment of the present invention.

FIG. 11 is a diagram illustrating a biosignal that passes through a buffer for explaining a non-contact heart rate measuring sensor according to an exemplary embodiment of the present invention.

12 is a circuit diagram illustrating an amplifier for explaining a non-contact heart rate measurement sensor according to an embodiment of the present invention.

FIG. 13 is a circuit diagram illustrating a ground for explaining a non-contact heart rate measuring sensor according to an exemplary embodiment of the present invention.

14 is a circuit diagram illustrating a power supply unit for explaining a non-contact heart rate measuring sensor according to an embodiment of the present invention.

15 is a schematic flowchart illustrating a signal processing method using a non-contact heart rate measurement sensor according to an embodiment of the present invention.

Brief description of the main parts of the drawing

100: electrode 110: LC oscillator

120: inverter 130: phase synchronization circuit

140: buffer 150: RC low pass filter

160: amplifier

Claims (7)

An electrode unit in which electrical capacity is charged due to a heartbeat; An LC oscillator for oscillating a biosignal due to a heartbeat according to an electrical capacitance charged by the electrode portion; An inverter for converting the oscillated frequency signal outputted through the LC oscillator into a square wave signal known to the machine; A phase synchronization circuit configured to synchronize the phase of the biosignal converted through the inverter so that the converted biosignal output through the inverter is not changed by ambient noise; A buffer for buffering the biosignal output through the phase synchronization circuit; An RC low pass filter filtering the biosignal output through the buffer; And And a amplifier for amplifying the biosignal filtered through the RC low pass filter. The method of claim 1, wherein the phase synchronization circuit A contactless heart rate sensor, characterized in that a capacitor is formed adjacent to the VDD input pin to effectively remove the noise of the output signal. The method of claim 1, wherein the RC low pass filter A non-contact heart rate measuring sensor which passes only a frequency band of 30 kHz or less. The method of claim 1, wherein the amplifier The contactless heart rate measuring sensor, characterized in that for amplifying the frequency corresponding to the biological signal passing through the RC low pass filter 15 to 25 times. Measuring the biosignal due to the heartbeat through the electrode unit and the LC oscillator; Converting the measured heart rate biosignal into a square wave that a machine can know through an inverter; Synchronizing the phase of the biosignal converted into the square wave through a phase synchronization circuit; Buffering the phase-locked biosignal; Filtering the buffered biosignal; And A signal processing method using the contactless heart rate measuring sensor comprising the step of amplifying the filtered biological signal. The method of claim 5, The filtering step is a signal processing method using a non-contact heart rate measurement sensor, characterized in that only passing the biological signal of the frequency band of 30kHz or less. The method of claim 5, And the amplifying step amplifies a frequency corresponding to the biological signal passed through the filtering step by 15 to 25 times.

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