KR101227413B1 - Electrical contactless bio-electrical signal measurement apparatus and the method of the same - Google Patents

Abstract

The present invention provides a non-contact biosignal measuring apparatus and its measuring method. The device includes a first electrode that is not in direct electrical contact with the human body, a second electrode that is spaced apart from the first electrode and is not in direct electrical contact with the human body, a first shear amplification circuit connected to the first electrode, and a second electrode. And a differential amplifier configured to extract the bioelectrical signal by using the connected second shear amplifier circuit, and the first output signal of the first shear amplifier circuit and the second output signal of the second shear amplifier circuit.

Description

 Electrical contactless bio-signal measuring apparatus and its method TECHNICAL FIELD

The present invention relates to a method and apparatus for measuring electrocardiogram (ECG) and / or respiration by electrical non-contact, and more specifically, it is possible to obtain an electrocardiogram signal and / or respiration signal by electrical non-contact sitting on a subject's clothes. The present invention relates to a method and an apparatus.

The present invention is derived from the research conducted by the research fund support (project number-2010K000827) of the 21st century frontier R & D project of the Ministry of Education, Science and Technology.

Electrocardiogram (ECG) signals are human electrical signals associated with cardiac activity, and respiratory signals are signals of lung movement. These signals are used as a major means for diagnosing heart and lung diseases and as a key means for monitoring basic life activities.

ECG signals are used for various diagnostics in the form of their signals. However, heart rate variability (HRV) is due to a change in the R-R interval of the ECG signal. The heart rate variability (HRV) analysis may be used to identify autonomic nervous system information.

Conventional ECG devices are configured to attach and measure a conductive electrode to the subject's skin. A plurality of electrodes are attached to the subject's skin, and connecting lines connect between the electrodes and the ECG device.

One technical problem to be solved of the present invention is to provide a measuring device that can measure the electrocardiogram and / or breathing in a state in which the subject is dressed without electrical contact.

One technical problem to be solved of the present invention is to provide a measuring method that can measure the electrocardiogram and / or breath in a state in which the subject is dressed without electrical contact.

The biosignal measuring apparatus according to an exemplary embodiment of the present invention may include a first electrode that is not in direct electrical contact with a human body, a second electrode that is spaced apart from the first electrode and is not in direct electrical contact with the human body, the first electrode Bioelectricity is achieved using a first shear amplification circuit connected to an electrode, a second shear amplification circuit connected to the second electrode, and a first output signal of the first shear amplification circuit and a second output signal of the second shear amplification circuit. It includes a differential amplifier for extracting the signal.

The measuring device according to an embodiment of the present invention may measure an ECG signal or a respiration signal without an electrical contact in a state where a subject wears clothes. The shear amplifier circuit is not entirely determined by the performance of the operational amplifier (Op-amp) having a high impedance characteristic, and a separate additional circuit improves the performance of the shear amplifier circuit. Therefore, op-amp selection for the implementation of the shear amplifier is wide.

The measuring device may be implemented in the form of a cushion, a seat, a chair, a vehicle chair, a sofa, a bed, an incubator, or a band in an electrical contactless manner. The measuring device may easily provide at least one of an electrocardiogram (ECG), a heart rate pulse signal, a heart rate variability (HRV) signal, and a breathing signal even in a daily living environment.

In particular, when implemented in a bed, the measuring device can be utilized as a patient monitoring device for infants and young children. In newborns, all kinds of measuring electrodes must be attached to the skin. However, the measuring device can monitor the life support state while the patient wearing the clothing is lying in the bed.

1 is an equivalent circuit model of a contact biosignal measuring apparatus.
2 shows an equivalent circuit model illustrating electrical non-contact signal measurement in accordance with an embodiment of the present invention.
3 illustrates a signal magnitude ratio Vo / Vs according to the equivalent capacitance Cs and the frequency of the biosignal Vs described with reference to FIG. 2.
4 is a view for explaining a method of securing a bias path according to an embodiment of the present invention.
5 is a diagram illustrating a sensor circuit according to an exemplary embodiment of the present invention.
6 illustrates a sensor circuit according to another embodiment of the present invention.
7 is a view for explaining a sensor circuit according to another embodiment of the present invention.
8 is a view for explaining a sensor circuit according to another embodiment of the present invention.
9 to 12 are diagrams illustrating a sensor circuit according to still another embodiment of the present invention.
FIG. 13 is a diagram illustrating a biosignal measuring apparatus according to an exemplary embodiment. Referring to FIG.
14 is a diagram illustrating a differential amplifier circuit 826 according to an embodiment of the present invention.
15 and 16 are diagrams illustrating a measuring device according to other embodiments of the present invention.
17A and 17B are diagrams illustrating a measuring apparatus according to an embodiment of the present invention.
18 is a view for explaining a measuring device according to an embodiment of the present invention.
FIG. 19 is a time differential ECG signal DV _ECG and its heart rate pulse signal measured using the measuring apparatus of FIG. 13.
20A through 20D are signals passing through an acceleration signal in the z-axis direction, a filtered acceleration signal, a time differential ECG signal, and a band cancellation filter of the acceleration sensor measured using the measuring device of FIG. 13.
21 to 27 are diagrams illustrating a measuring apparatus according to still another embodiment of the present invention.
FIG. 28 illustrates a respiration signal V _RSP , a time differential ECG signal DV _ECG , and a heart rate pulse signal V _HBP measured using the biosignal measuring apparatus of FIG. 15.
29A and 29B are results obtained using a measuring apparatus according to an embodiment of the present invention.

In electrocardiogram measurement using a contact electrocardiogram device, the subject must attach the corresponding electrode to the surface of the skin for electrocardiogram signal measurement and endure the effort constrained by the contact electrocardiogram device. The contact measurement method directly attaches a conductive electrode to human skin to measure an ECG signal.

Non-contact measuring method according to an embodiment of the present invention is a method that can measure the ECG signal without direct electrical contact with the human skin of the subject. Thus, the ECG signal can be measured while the subject is dressed.

In bioelectrical signal measurement, the impedance of the signal source is quite large. Therefore, the conductive electrode was directly attached to the human body, and the bioelectrical signal was measured.

However, if the biometric signal can be obtained in a state where the subject is dressed or in a state where the measurement sensor and the subject are separated, the psychological constraint of the subject may be removed. In addition, the non-contact measuring sensor can measure the bioelectrical signal through an insulator even in an environment not in close contact with the human body. The bioelectrical signal may be brain wave, electrocardiogram, safety, and electromyogram, or breathing.

The non-contact metrology method according to an embodiment of the present invention can measure the electrical potential of the skin surface without direct electrical contact with the skin of the subject. The difference in the potentials of the at least two measuring electrodes can provide an ECG signal or a breathing signal. The key to realizing the measurement of the electrocardiogram signal is high input impedance pre-amplifier circuit and differential amplification circuit technology that provides signal measurement in a non-contact manner.

Non-contact measuring method according to an embodiment of the present invention provides the following problem solving. Stable operation of the shear amplifier circuit can be solved by the bias circuit. In addition, signal attenuation by capacitive voltage distribution can be solved by the capacitive feedback circuit. The equivalent input resistance (or effective input resistance) of the shear amplifier circuit can be solved by the resistive feedback circuit.

Hereinafter, a sensor for realizing electrical non-contact measurement will be described.

[Difference between traditional contact measurement method and non-contact measurement method]

1 is a simple equivalent circuit model of a contact biosignal measuring apparatus.

Referring to FIG. 1, the biosignal measuring apparatus measures a biosignal using a conductive electrode. The biopotential (Vs) formed in the human body is transmitted to the input of the biosignal measuring apparatus through the impedance or contact resistance (Rs) of the signal source existing between the electrode (not shown) and the skin. The biosignal measuring apparatus includes a shear amplifier 10. The front end amplifier 10 has its own input resistance Ri and its own input capacitance Ci. The gain of the front end amplifier 10 may be one. In this case, the output signal Vo of the shear amplifier may be given as follows.

Here, j represents a complex number and ω represents an angular frequency of the input signal or the biopotential (Vs) of the shear amplifier. The frequency of the input signal is about 10 Hz, the impedance or contact resistance (Rs) of the signal source is 10 kΩ, the input resistance (Ri) of the shear amplifier is 10 TΩ, and the input capacitance (Ci) of the shear amplifier. In the case of 10 pF, Equation 1 can be approximated as follows.

In a traditional bioelectrical signal measuring scheme, the output signal Vo is approximately equal to the biopotential Vs. Therefore, the biopotential Vs can be measured with little loss.

2 shows a simple equivalent circuit model illustrating electrical non-contact signal measurement in accordance with one embodiment of the present invention.

Referring to FIG. 2, in the non-contact signal measurement, an equivalent capacitor (capacitive Cs) formed between the human body and the non-contact electrode (not shown) is placed in place of the contact resistance Rs disposed between the human body and the biological signal measuring device. . The biosignal measuring apparatus may include a shear amplifier 20. The gain of the front end amplifier 20 may be one. The front end amplifier 20 has its own input resistance Ri and its own input capacitance Ci. In this equivalent circuit, the output signal Vo for the biosignal Vs can be expressed as follows.

The equivalent capacitance Cs formed between the human body and the non-contact electrode may have various values depending on the situation.

FIG. 3 illustrates the signal capacitance ratio Vo / Vs according to the frequency change of the equivalent capacitance Cs and the biosignal Vs described with reference to FIG. 2.

2 and 3, the equivalent capacitance Cs and its own input resistance Ri of the shear amplifier 20 form a high pass filter HPF. When the frequency of the biosignal Vs is 10 Hz, the cut-off frequency of the high pass filter HPF may be lower than the frequency of the biosignal Vs. Thus, there is no signal attenuation by the high pass filter HPF.

However, the magnitude of the output signal Vo varies considerably with the magnitude of the equivalent capacitance Cs. If the frequency of the biosignal Vs is significantly greater than the cutoff frequency by the high pass filter HPF, the magnitude of the second term of the denominator can be relatively neglected in Equation 3. In this case, the magnitude of the output signal Vo is given as follows.

Comparing equations (4) and (2), the non-contact signal measurement can cause significant attenuation of the output signal Vo. Thus, in some cases, contactless signal measurement may not be possible.

 The front amplifier 20 may use an operational amplifier (OP-AMP). As the magnitude of the self input capacitance Ci of the front end amplifier 20 is smaller, the magnitude of the output signal Vo increases. In addition, as the equivalent capacitance Cs between the non-contact electrode and the human body increases, the magnitude of the output signal Vo increases.

Equations 2 and 4 show the critical difference between contact measurement and contactless measurement. The magnitude of the output signal Vo can typically be amplified using an amplifier (not shown) disposed behind the front end amplifier 20. In this case, however, the amplifier also amplifies the noise. Therefore, it is difficult to discriminate the signal and the noise.

 Referring to Equation 4, in order to detect the contactless signal, the self-input capacitance Ci of the front-end amplifier 20 needs to be reduced, and at the same time, the equivalent capacitance Cs between the non-contact electrode and the human body needs to be increased. There is a need for a sensor circuit comprising the front end amplifier 20 such that the signal magnitude ratio Vo / Vs is close to one.

Another difference between the contact detection method and the non-contact detection method is the presence or absence of a path through which the bias DC current Ib for driving the shear amplifier. The input bias current path of the front end amplifier 20 is necessary for the correct operation of the front end amplifier.

Referring back to FIG. 1, in the contact detection method, the input terminal of the front end amplifier is connected to the ground of the front end amplifier 10 via a ground electrode (not shown) attached to the human skin through the contact resistance Rs of the skin. There is a flowing bias current path.

Referring again to FIG. 2, in the non-contact detection method, there is no separate current path through which the bias current flows. There may be a path through its input resistance Ri of the front end amplifier 20. This path does not guarantee stable operation of the shear amplifier 20. The output of the front end amplifier 20 may be saturated by the bias current Ib and its own input resistance Ri. Thus, normal operation of the front end amplifier 20 is not guaranteed. Thus, the non-contact detection method is difficult to achieve easily.

[Bias Circuit for Stable Amplifier Operation]

In order to measure the signal in a non-contact manner, the above-mentioned problems (signal attenuation due to capacitive voltage distribution and amplifier inoperability due to inaccurate bias current paths) must be solved.

First, correct operation of the shear amplifier is required. Thus, the circuit formation of the bias path is considered.

4 illustrates the simplest method of securing a bias path.

Referring to FIG. 4, a bias resistor 32 is inserted between the input terminal of the front end amplifier 30 and the ground GND. The bias current Ib present at the input of the front end amplifier 30 flows to ground through the bias resistor 32. Thus, a bias current path is formed so that the front end amplifier 30 can operate normally.

However, in this case, the voltage drop caused by the bias current Ib and the bias resistor 32 should be smaller than the driving voltage and the input common mode voltage of the front amplifier 30. The bias resistor 32 introduced in circuit is connected in parallel with its own input resistance Ri of the front end amplifier 30. The resistance value of the bias resistor 32 is usually significantly less than its own input resistance Ri of the shear amplifier 30. Therefore, in Equation 3, the self input resistance Ri of the front end amplifier 30 may be replaced with the bias resistor 32.

Referring to Equation 3, the high capacitance filter HPF formed by the equivalent capacitance Cs and the bias resistor 32 may provide a variation in the magnitude of the output signal Vo according to the change of the signal frequency. Can be. That is, the output signal Vo is attenuated by the capacitive voltage distribution by the equivalent capacitance Cs and its own input capacitance Ci of the front end amplifier 30, and the equivalent capacitance Cs and the Accompanied by signal attenuation due to the high pass filter HPF by the bias resistor 32.

In order to reduce signal attenuation caused by the high frequency pass filter HPF by the bias resistor 32, it is preferable to separate the signal circuit and the bias circuit. That is, the bias circuit of the direct current (DC) component is composed of a circuit having a low impedance, and the signal circuit of the alternating current (AC) component is configured to have a high impedance.

5 is a diagram illustrating a bootstrap sensor circuit.

Referring to FIG. 5, the bootstrap sensor circuit may include a first amplifier 41 and bias resistors 42a and 42b. The first bias resistor 42a and the second bias resistor 42b may be connected in series between the positive input terminal of the first amplifier 41 and ground. The output terminal of the first amplifier 41 may be directly connected to the negative input terminal of the first amplifier 41. The bias capacitor 44 may be connected between the output terminal of the front end amplifier 41 and the contact point N1 of the first bias resistor 42a and the second bias resistor 42b.

The first bias resistor 42a and the second bias resistor 42b provide a path through which a direct current (DC) bias current Ib flows. In addition, the first bias resistor 42a and the second bias resistor 42b may be set to have a relatively low impedance. The bias capacitor 44 acts as a short circuit for a signal of an alternating current (AC) component. Therefore, there is almost no potential difference across the first bias resistor 42a with respect to the signal of the alternating current (AC) component, and a high impedance circuit is provided.

4 and 5 are ground biases where the bias current flows directly through the bias resistor to ground (GND).

6 is a diagram illustrating a sensor circuit according to an exemplary embodiment of the present invention.

Referring to FIG. 6, the sensor circuit uses a floating bias. The floating bias can actively adjust the magnitude of the input bias according to the magnitude of the direct current (DC) component present at the output of the first amplifier 51. One end of the bias resistor is connected to floating potential Vb rather than ground GND.

In the non-contact signal measurement, an equivalent capacitor (capacitive Cs) formed between the human body and the non-contact electrode (not shown) is placed in place of the contact resistance Rs disposed between the human body and the biological signal measuring device.

The sensor circuit receives a measurement signal Vs of a signal source through the equivalent capacitor to a positive input terminal and transmits the measured signal Vs to an output terminal and an output terminal of the first amplifier 51 and the first amplifier ( And a bias circuit 53 disposed between the positive input ends of 51 to ensure stable operation of the first amplifier 51. The negative input terminal of the first amplifier 51 is directly connected to the output terminal of the first amplifier 51 so that the gain of the first amplifier 51 is 1, and the first amplifier 51 has a voltage follower ( voltage follower).

The bias circuit 53 receives an output of the first amplifier 51 to perform time integration, an inverted amplifier circuit 56, a positive input terminal of the first amplifier 51, and the inverted amplifier circuit 56. A first bias resistor 52a and a second bias resistor 52b connected in series between the outputs, and a contact point N1 of the first bias resistor 52a and the second bias resistor 52b and the first amplifier; And a bias capacitor 54 disposed between the output ends of 51.

The integrating integrating circuit 56 includes a bias amplifier 55, a reference voltage source 156 connected to the positive input terminal of the bias amplifier 55, an output terminal of the first amplifier 51 and a negative voltage of the bias amplifier 55. An integral resistor 58 disposed between the input terminals of and an integration capacitor 57 connected between the output terminal of the bias amplifier 55 and the negative input terminal of the bias amplifier 55. The output terminal of the bias amplifier 55 is connected to the second bias resistor 52b.

The potential Vr of the reference voltage source 156 may be 0 V when the first amplifier 51 is driven by a positive power source having a ± V driving voltage. Alternatively, the potential of the reference voltage source 156 may be V / 2 when the first amplifier 51 is driven by a single pole power source having a + V driving voltage.

One end of the second bias resistor 52b is connected to the contact point N1, and the other end of the second bias resistor Rb2 is connected to the floating potential Vb instead of the ground GND. The floating potential Vb is a potential of the output terminal of the inverting integration circuit 56.

The floating bias method has an advantage of allowing the DC component of the output of the first amplifier 51 to be equal to the reference voltage Vr of the inverting amplifier circuit 56. The inversion integrated circuit 56 provides a floating potential Vb to the second bias resistor 52b so that the output voltage Vo of the first amplifier 51 is at the reference voltage Vr level. The potential difference due to the first and second bias resistors 52a and 52b and the bias current Ib and the floating potential Vb contribute to the input potential Vin of the positive input terminal of the first amplifier 51. The input potential Vin is represented as an output signal Vo at an output terminal of the first amplifier 51. Thus, a stable bias condition of the first amplifier 51 is formed.

The bias circuit 53 serves as a high frequency pass filter HPF with respect to the input potential Vin. That is, the integral resistor 58 and the integral capacitor 57 determine the cutoff frequency of the high frequency pass filter HPF with respect to the input potential Vin.

[Signal Noise Due to Relative Movement Between Human Skin and Measuring Electrode]

7 is a view for explaining a sensor circuit according to another embodiment of the present invention.

Referring to FIG. 7, the sensor circuit includes a first amplifier 251 for receiving a measurement signal of a signal source, directly or indirectly, from a positive input terminal and transferring the measured signal to an output terminal, and an output terminal and ground of the first amplifier 251. A bias circuit 253 disposed between at least one and a positive input terminal of the first amplifier 251 to ensure stable operation of the first amplifier. The negative input terminal of the first amplifier 251 is directly connected to the output terminal of the first amplifier 251 so that the gain of the first amplifier 251 is 1, and the first amplifier 251 is a voltage follower ( voltage follower).

 The resistive feedback circuit 270 is disposed between the positive input terminal of the first amplifier 251 and the output terminal of the first amplifier 251, and receives the output signal of the output terminal of the first amplifier 251. A resistive feedback current is provided to the positive input of the first amplifier 251 to increase the effective input resistance of the first amplifier 251.

The capacitive feedback circuit 280 is disposed between the positive input terminal of the first amplifier 251 and the output terminal of the first amplifier 251, and receives the output signal of the output terminal of the first amplifier 251. Capacitive feedback current is provided to the positive input of the first amplifier 251 to reduce the effective input capacitance of the first amplifier 251.

In the non-contact signal measurement, the equivalent capacitance Cs formed between the human skin 201 and the non-contact measurement electrode 202 is placed. In contactless biosignal measurement, noise due to relative movement between human skin 201 and contactless measurement electrode 202 will be discussed. Human skin 201 has a biosignal Vs.

Referring to Equation 4, as the magnitude of the equivalent capacitance Cs increases, the magnitude of the output signal Vo increases. That is, variations in the equivalent capacitance Cs values caused by the human skin 201 and the measurement electrode 202 appear as noise in the output signal Vo of the first amplifier 251. The change in distance between the measuring electrode 202 and the human skin 201 is output as a noise much larger than the output signal Vo.

The influence of relative movement between the measurement electrode 202 and the human skin 201 needs to be reduced. Referring to Equation 4, by reducing the dependence of the equivalent capacitance (Cs), the effect of the relative movement between the measurement electrode 202 and the human skin 201 can be reduced. For this purpose, a coupling capacitor 204 is connected in series between the measuring electrode 202 and the positive input of the first amplifier 251. The coupling capacitor 204 has a coupling capacitance Cc. The equivalent capacitance Cs and the combined capacitance Cc form a series connection of capacitors. Therefore, the net total combined capacitance Ct can be expressed as follows.

The net coupling capacitance Ct is always less than or equal to the coupling capacitance Cc. In addition, the net coupling capacitance Ct may be used in place of the equivalent capacitance Cs in the equations (3) and (4).

If the equivalent capacitance Cs is set at a level 10 times the coupling capacitance Cc, the net coupling capacitance Ct is approximately equal to the coupling capacitance Cc. In this case, the variation in the equivalent capacitance Cs hardly contributes to the change in the net coupling capacitance Ct. As a result, variations in the equivalent capacitance Cs due to the change in distance between the measuring electrode 202 and the human skin 201 are hardly seen at the sensor output Vo.

Therefore, the minor influence due to the relative movement between the human skin 201 and the measuring electrode 202 can be ignored.

[Solution of Signal Attenuation Problem by Capacitive Voltage Distribution]

Next, the problem of signal attenuation due to the equivalent capacitance Cs formed between the human skin 201 and the measurement electrode 202 and the self input capacitance Ci of the first amplifier 251 is considered. Referring to Equation 4, the larger the equivalent capacitance (Cs), the smaller the self input capacitance (Ci), the larger the output signal (Vo) of the sensor circuit.

In order to increase the equivalent capacitance Cs, the size of the measuring electrode 202 in contact with the measuring portion may be increased or the distance between the human skin 201 and the measuring electrode 202 may be reduced. However, the fabric of the examinee may be placed between the human skin 201 and the measurement electrode 202. Therefore, the reduction in the distance between the human skin 201 and the measuring electrode 202 is limited.

For example, a circular measuring electrode 202 having a diameter of 6 cm may form a capacitor at a distance of 1 mm from human skin. In this case, the equivalent capacitance Cs of the capacitor is on the order of 25 pF. Considering that the self-input capacitance Ci of the first amplifier 251 is approximately 10 pF, the ratio of the output signal Vo to the input signal Vs is 0.71 in Equation 4. If the size of the measuring electrode 202 is further increased, the equivalent capacitance Cs may have a larger value. However, there is a limit in increasing the size of the measuring electrode 202. Thus, further efforts are needed to reduce the self input capacitance Ci of the first amplifier 251.

The primary task is to select a component having a small self-input capacitance Ci of the operational amplifier OP-AMP used as the first amplifier. But this is not the ultimate solution. Whatever components are used, there is a need for a circuit solution to reduce the effective input capacitance Ce of the first amplifier. The effective input capacitance Ce refers to the input capacitance Ce of the sensor circuit including the first amplifier. This value replaces the amplifier's own input capacitance Ci in equation (4).

8 is a view for explaining a sensor circuit according to another embodiment of the present invention.

Referring to FIG. 8, the sensor circuit may include at least one of a first amplifier 351 that receives a measurement signal Vs as a positive input terminal and transmits the measured signal Vs to an output terminal, and an output terminal and ground of the first amplifier 351 and the ground. A bias circuit disposed between the positive input terminals of the first amplifier 351 to ensure stable operation of the first amplifier 351.

 The negative input terminal of the first amplifier 351 is directly connected to the output terminal of the first amplifier 351 so that the gain of the first amplifier 351 is 1, and the first amplifier 351 is a voltage follower ( voltage follower).

The capacitive feedback circuit 380 is disposed between the positive input terminal of the first amplifier 351 and the output terminal of the first amplifier 351, and receives the output signal of the output terminal of the first amplifier 351. The capacitive feedback voltage Vcf greater than the potential of the input terminal of the first amplifier 351 is provided to the positive input terminal of the first amplifier 351 through a feedback capacitor 382, thereby providing Reduce the effective input capacitance Ce.

The capacitive feedback circuit 380 receives an output of the first amplifier 351 and receives a non-inverting amplifier circuit 385 having a gain greater than 1, and an output of the non-inverting amplifier circuit 385 and the first. A feedback capacitor 382 is coupled between the positive input ends of the amplifier 351.

The non-inverting amplifier circuit 385 includes a capacitive feedback amplifier 381, a first gain resistor 383 connected between the negative input terminal of the capacitive feedback amplifier 381 and ground, and the capacitive feedback amplifier 381. And a second gain resistor 384 coupled between the negative input and output terminals of. The positive input of the capacitive feedback amplifier 381 is connected to the output of the first amplifier, and the output of the capacitive feedback amplifier 381 is connected to one end of the feedback capacitor 382. The other end of the feedback capacitor 382 is connected to the positive input end of the first amplifier 351.

In terms of the positive input stage of the first amplifier 351, the self-input capacitance Ci (not shown) and the feedback capacitances 382 and Cf of the first amplifier 351 are in parallel coupled with each other. Therefore, the effective input capacitance Ce of the first amplifier 351 may be expressed as an arithmetic sum of the self input capacitance Ci of the first amplifier and the feedback capacitances 382 and Cf. The self input capacitance Ci of the first amplifier is an capacitance formed between the input potential Vin and the ground GND of the first amplifier. The self input capacitance Ci thus contributes a positive value. On the other hand, the feedback capacitances 382 and Cf are capacitances formed between the input potential Vin of the first amplifier 351 and the capacitive feedback voltage Vcf, and the capacitive feedback voltage Vcf is always The feedback capacitances 382 and Cf contribute to a negative value because they exist in phase while having a value greater than the input potential Vin of the first amplifier. The degree of contribution depends on the degree of difference between the capacitive feedback voltage Vcf and the input potential Vin. As a result, the effective input capacitance Ce of the first amplifier always has a value smaller than the self input capacitance Ci of the first amplifier.

The size control of the effective input capacitance Ce of the sensor circuit including the first amplifier 351 using the positive feedback circuit scheme may be applied independently of the bias condition of the first amplifier 351. Thus, for any bias circuit, the effective input capacitance Ce can be reduced in a positive feedback manner.

[Improving Amplifier Equivalent Input Resistance]

Referring again to FIG. 4, the value of the bias resistor 32 connected to the input terminal of the first amplifier 30 for the stable operation of the first amplifier 30 is the self input resistance Ri of the first amplifier 30. Much smaller than that. Thus, in equation 3 the second term of the denominator can no longer be ignored.

Typically, the bias resistor 32 is at the 100 GΩ level. The input resistance Ri of the first amplifier 30 is about 10 TΩ. The value of the self input resistance Ri of the first amplifier 30 is 100 times larger than the bias resistance 32.

There is a need for a circuit compensation means that connects the bias resistor 32 but does not recognize the bias resistor 32 as an impedance from a signal point of view. The compensation means may eliminate signal attenuation due to the action of the high frequency pass filter HPF formed by the equivalent capacitance Cs and the bias resistor Rb.

9 is a view for explaining a sensor circuit according to another embodiment of the present invention.

Referring to FIG. 9, the sensor circuit may include a first amplifier 451 which receives a measurement signal Vs as a positive input terminal and transmits the measured signal Vs to an output terminal, and

A bias circuit 453 disposed between at least one of an output terminal and ground of the first amplifier 451 and a positive input terminal of the first amplifier 451 to ensure stable operation of the first amplifier 451. do.

The negative input terminal of the first amplifier 451 is directly connected to the output terminal of the first amplifier 451 so that the gain of the first amplifier 451 is 1, and the first amplifier 451 is a voltage follower ( voltage follower).

The resistive feedback circuit 470 is disposed between the positive input terminal of the first amplifier 451 and the output terminal of the first amplifier 451, and receives the output signal of the output terminal of the first amplifier 451. A resistive feedback voltage Vrf greater than the potential of the input terminal of the first amplifier 451 is provided to the positive input terminal of the first amplifier 451 via a feedback resistor 472 to provide an effective input of the first amplifier 451. Increase the resistance (Re).

The resistive feedback circuit 470 receives an output of the first amplifier 451 and has a gain greater than one, and an output of the non-inverting amplifier circuit 475 and the first amplifier. And a feedback resistor 472 coupled between the positive input of 451.

The non-inverting amplifier circuit 475 includes a resistive feedback amplifier 471, a negative gain of the resistive feedback amplifier 471 and a first gain resistor 473 connected between the negative input terminal of the resistive feedback amplifier 471 and ground. And a second gain resistor 474 coupled between the input and output terminals. The positive input terminal of the resistive feedback amplifier 471 is connected to the output terminal of the first amplifier 451, and the output terminal of the resistive feedback amplifier 471 is connected to one end of the feedback resistor 472. The other end of the feedback resistor 472 is connected to the positive input end of the first amplifier 451.

In terms of the positive input stage of the first amplifier 451, the self-input resistor Ri (not shown) of the first amplifier, the bias resistor Rb (not shown) included in the bias circuit 453, and the feedback resistor are included. 472 and Rf are connected to each other in parallel. Accordingly, the inverse of the effective input resistance Re of the first amplifier 451 is the inverse of the self input resistance Ri of the first amplifier 451, the inverse of the bias resistor Rb, and the feedback resistance 472. It can be expressed as the arithmetic sum of the inverse of Rf). The self input resistance Ri of the first amplifier is an electrical resistance formed between the input potential Vin of the first amplifier 451 and the ground GND. The self input resistance Ri thus contributes to a positive inverse value. The bias resistor Rb is a resistor formed between the input potential Vin of the first amplifier 451 and the ground GND or the floating potential Vb (not shown) and contributes to a positive inverse value. On the other hand, the feedback resistors 472 and Rf are electrical resistances formed between the input potential Vin of the first amplifier 451 and the resistive feedback voltage Vcf, and the resistive feedback voltage Vrf is always the first. The feedback resistors 472 and Rf contribute to negative reciprocal values because they are in phase with a value greater than the input potential Vin of the amplifier. The degree of contribution depends on the degree of difference between the resistive feedback voltage Vrf and the input potential Vin. As a result, the effective input resistance Re of the first amplifier always has a value greater than the harmonic mean of its own input resistance Ri and the bias resistor Rb of the first amplifier.

The size control of the effective input resistance Re of the sensor circuit including the first amplifier 451 in the above-described manner may be applied independently of the bias circuit, the capacitive feedback circuit, and the like. A bias circuit is necessary for the stable operation of the first amplifier. A resistive feedback circuit that increases the effective input resistance Re or a capacitive feedback circuit that reduces the effective input capacitance can optionally be provided to the sensor circuit.

[Sensor Circuits for Realizing Electrical Non-Contact Measurements]

Referring back to FIG. 7, a sensor circuit for implementing an electrical non-contact potential sensor includes a first amplifier 251 and a bias circuit 253. However, a resistive feedback circuit 270 that increases the effective input resistance Re of the first amplifier 251 or a capacitive feedback circuit 280 that reduces the effective input capacitance may be selectively introduced.

The bias circuit 253 may be a ground bias, a bootstrap ground bias, and a floating bias circuit. The sensor circuit may include the resistive feedback circuit 270 and / or the capacitive feedback circuit 280.

10 is a diagram illustrating a sensor circuit according to an exemplary embodiment of the present invention.

Referring to FIG. 10, the sensor circuit may include a first amplifier 551 that receives a measurement signal Vs of a signal source, directly or indirectly, as a positive input terminal, and transmits it to an output terminal, and an output terminal of the first amplifier 551. A bias circuit 553 is disposed between the positive input terminals of the first amplifier 551 to ensure stable operation of the first amplifier 551.

The negative input terminal of the first amplifier 551 is directly connected to the output terminal of the first amplifier 551 so that the gain of the first amplifier 551 is 1, and the first amplifier 551 is a voltage follower ( voltage follower).

The measuring electrode 502 is disposed adjacent to and electrically contactless with the signal source. The measurement electrode 502 may be made of metal, and one surface of the measurement electrode 502 facing the measurement object or signal source may be coated with an insulator. The measuring electrode 502 may be formed of a conductive fabric or modified in various forms.

The coupling capacitor 504 may be connected in series between the measuring electrode 502 and the positive input terminal of the first amplifier 551. The capacitance Cc of the coupling capacitor 504 may be smaller than the equivalent capacitance Cs formed between the signal source and the measurement electrode 502. Preferably, the capacitance Cc of the coupling capacitor 504 may be about 1/10 times the equivalent capacitance Cs.

The guard part 506 surrounds all or part of the measuring electrode 502 or the coupling capacitor 504. The guard part 506 is one surface of the measurement electrode 502 connected to the coupling capacitor 504, a conductor connecting the coupling capacitor 504 and the measurement electrode 502, and the coupling capacitor 504. ) May be wrapped around at least one. The guard unit 506 may be connected to an output terminal of the first amplifier 551 and maintained at the same voltage as the output voltage Vo. The guard part 506 may be a conductive net or a conductive cable.

The sensor circuit includes a first amplifier 551, a bias circuit 553, and a feedback circuit 570. The bias circuit 553 may be a floating bias circuit.

The bias circuit 553 may include a second amplifier 555, a bias resistor 552, an integrated capacitor 557, and an integrated resistor 558. The second amplifier 555 receives the output signal of the output terminal of the first amplifier 551 and provides a bias current to the positive input terminal of the first amplifier 551.

The bias resistor 552 is connected between the positive input terminal of the first amplifier 551 and the output terminal of the second amplifier 555. The integrating capacitor 557 is connected between the output terminal of the second amplifier 555 and the negative input terminal of the second amplifier 555. An integration resistor 558 is connected between the negative input of the second amplifier 555 and the output of the first amplifier 551.

The positive input terminal of the second amplifier 555 is connected to a reference potential 556 (Vr). The reference potential is the output Vo reference potential of the first amplifier. When the driving power of the amplifiers is ± V positive power, the reference potential may be 0V (ground, GND). On the other hand, if the driving power supply is a + V single power supply, the reference potential may be V / 2.

The feedback circuit 570 includes a third amplifier 571, a feedback capacitor 572b, a feedback resistor 572a, a first resistor 573, and a second resistor 574. The third amplifier 571 provides a feedback current to the positive input terminal of the first amplifier 551. The feedback capacitor 572b is connected between the positive input terminal of the first amplifier 551 and the output terminal of the third amplifier 571. The feedback resistor 572a is connected in parallel with the feedback capacitor 572b. The first resistor 573 is connected between the negative input terminal of the third amplifier 571 and the reference potentials 575 and Vr. The reference potentials 575 and Vr have the same value as the reference potentials 556 and Vr of the bias circuit 553. The second resistor 574 is connected between the output terminal of the third amplifier 571 and the negative input terminal of the third amplifier 571. The positive input terminal of the third amplifier 571 is connected to the output terminal of the first amplifier.

11 illustrates a sensor circuit according to an embodiment of the present invention.

Referring to FIG. 11, the sensor circuit receives a measurement signal Vs of a signal source, directly or indirectly, from a positive input terminal and delivers it to an output terminal, and a positive amount of the first amplifier 651. A bias circuit 653 is disposed between the input terminal and the ground GND to ensure stable operation of the first amplifier 651. The negative input terminal of the first amplifier 651 is directly connected to the output terminal of the first amplifier 651 so that the gain of the first amplifier 651 is 1, and the first amplifier 651 has a voltage follower ( voltage follower).

The measuring electrode 602 is arranged in electrical contact with and adjacent to the signal source. The measurement electrode 602 may be made of a metal, and one surface of the measurement electrode 602 facing the measurement object may be coated with an insulator. The measuring electrode 602 may be formed of a conductive fabric or modified in various forms.

The coupling capacitor 604 may be connected in series between the measuring electrode 602 and the positive input terminal of the first amplifier 651. The capacitance Cc of the coupling capacitor 604 may be smaller than the equivalent capacitance Cs formed between the signal source and the measurement electrode 602. Preferably, the capacitance Cc of the coupling capacitor 604 may be about 1/10 times the equivalent capacitance Cs.

The guard portion 606 surrounds all or part of the measuring electrode 602 or the coupling capacitor 604. The guard part 606 is one surface of the measurement electrode 602 connected to the coupling capacitor 604, a conductor connecting the coupling capacitor 604 and the measurement electrode 602, and the coupling capacitor 604. ) May be wrapped around at least one. The guard unit 606 may be connected to an output terminal of the first amplifier 651 and maintained at the same voltage as its output voltage Vo. The guard part 606 may be a conductive net or a conductive cable.

The sensor circuit includes a first amplifier 651, a bias circuit 653, and a feedback circuit 670. The bias circuit 653 may be a ground bias circuit. The feedback circuit 670 may be a resistive feedback circuit.

The bias circuit 653 includes a bias resistor 652 connected between the positive input terminal of the first amplifier 651 and ground.

The feedback circuit 670 includes a third amplifier 671, a feedback resistor 672, a first resistor 673, and a second resistor 674. The third amplifier 671 provides a feedback current to the input terminal of the first amplifier 651. The feedback resistor 672 is connected between the output terminal of the third amplifier 671 and the positive input terminal of the first amplifier 651. The first resistor 673 is connected between the negative input terminal of the third amplifier 671 and the ground GND. The second resistor 674 is connected between the output terminal of the third amplifier 671 and the negative input terminal of the third amplifier 671. The positive input terminal of the third amplifier 671 is connected to the output terminal of the first amplifier 651, and the sensor circuit is driven by a positive power source.

12 illustrates a sensor circuit according to an embodiment of the present invention.

Referring to FIG. 12, the sensor circuit includes a first amplifier 751 that directly or indirectly receives a measurement signal Vs of a signal source and transmits it to an output terminal, and an output terminal of the first amplifier 751. A bias circuit 753 disposed between the positive input terminals of the first amplifier 751 to ensure stable operation of the first amplifier 751. The negative input terminal of the first amplifier 751 is directly connected to the output terminal of the first amplifier 751 so that the gain of the first amplifier 751 is 1, and the first amplifier 751 has a voltage follower ( voltage follower).

The measuring electrode 702 is disposed in electrical contact with and adjacent to the signal source. The measurement electrode 702 may be made of a metal, and one surface of the measurement electrode 702 facing the measurement object may be coated with an insulator. The measuring electrode 702 may be formed of a conductive fabric or modified in various forms.

The coupling capacitor 704 may be connected in series between the measuring electrode 702 and the positive input terminal of the first amplifier 751. The capacitance Cc of the coupling capacitor 704 may be smaller than the equivalent capacitance Cs formed between the signal source and the measurement electrode 702. Preferably, the capacitance Cc of the coupling capacitor 704 may be about 1/10 times the equivalent capacitance Cs.

The guard portion 706 surrounds all or part of the measuring electrode 702 or the coupling capacitor 704. The guard part 706 is one surface of the measurement electrode 702 connected to the coupling capacitor 704, a conductor connecting the coupling capacitor 704 and the measurement electrode 702, and the coupling capacitor 704. ) May be wrapped around at least one. The guard unit 706 may be connected to the output terminal of the first amplifier 751 and maintained at the same voltage as the output voltage Vo. The guard part 706 may be a conductive net or a conductive cable.

The sensor circuit includes a first amplifier 751, a bias circuit 753, and a capacitive feedback circuit 780. The bias circuit 753 may be a floating bias circuit.

The bias circuit 753 includes a second amplifier 755, first and second bias resistors 752a and 752b, an integrated capacitor 757, an integrated resistor 758, and a capacitor 754. The second amplifier 755 receives the output signal of the output terminal of the first amplifier 751 and provides a bias current to the positive input terminal of the first amplifier 751. The first and second bias resistors 752a and 752b are connected in series between the positive input terminal of the first amplifier 751 and the output terminal of the second amplifier 755. The integral capacitor 757 is connected between the output terminal of the second amplifier 755 and the negative input terminal of the second amplifier 755. The integration resistor 758 is connected between the negative input terminal of the second amplifier 755 and the output terminal of the first amplifier 751. The capacitor 754 is connected between the output terminal of the first amplifier 751 and the point of contact N1 of the first bias resistor 752a and the second bias resistor 752b.

The positive input terminal of the second amplifier 755 is connected to a reference potential 756, Vr. The reference potential is the output Vo reference potential of the first amplifier. When the driving power of the amplifiers is ± V positive power, the reference potential may be 0V (ground, GND). On the other hand, if the driving power supply is a + V single power supply, the reference potential may be V / 2.

The capacitive feedback circuit 780 includes a third amplifier 781, a feedback capacitor 782, a first resistor 783, and a second resistor 784. The third amplifier 781 provides a feedback current to an input terminal of the first amplifier 751. The feedback capacitor 782 is connected between the positive input terminal of the first amplifier 751 and the output terminal of the third amplifier 781. The first resistor 783 is connected between the negative input terminal of the third amplifier 781 and the reference potentials 785 and Vr. The reference potentials 785 and Vr have the same value as the reference potentials 756 and Vr of the bias circuit 753. The second resistor 784 is connected between the output terminal of the third amplifier 781 and the negative input terminal of the third amplifier 781. The positive input terminal of the third amplifier 781 is connected to the output terminal of the first amplifier.

[Configuration of Electrical Non-contact Biosignal Measurement System]

FIG. 13 is a diagram illustrating a biosignal measuring apparatus according to an exemplary embodiment. Referring to FIG.

Referring to FIG. 13, the measuring device may be spaced apart from the first electrode 812 and the first electrode 812, which is not in direct electrical contact with the human body 801, and may not directly contact the human body 801. A second front end amplification circuit connected to the first electrode 814, a ground electrode 816 disposed to be spaced apart from the second electrode 814, the first electrode and the second electrode, and not directly contacting the human body. 822, a second front end amplification circuit 824 connected to the second electrode 814, and a first output signal Vo1 and the second front end amplification circuit 824 of the first front end amplification circuit 822. And a differential amplifier 826 extracting the bioelectrical signal V _E using the second output signal Vo2.

The first electrode 812 is connected to the first shear amplifier circuit 822 through a connection line 821, and the second electrode 814 is connected to the second shear amplifier circuit 824 through a connection line 821. Is connected to. Each connection line 821 may be a guarded coaxial line.

The first electrode 812 is connected to the first shear amplifier circuit 822 through a connection line 821, and the second electrode 814 is connected to the second shear amplifier circuit 824 through a connection line 821. Is connected to. Each connection line 821 may be a guarded coaxial line.

The ground electrode 816 may be connected to the ground GND of the measuring device through a single lead. The ground electrode 816 may be spaced apart from the first electrode 812 and the second electrode 814 and may not directly contact the human body 801.

The first electrode 812, the second electrode 814, and the ground electrode 816 may be embedded in an electrical insulator and mounted on the hip part of the human body.

Alternatively, the first electrode 812, the second electrode 814, and the ground electrode 816 are embedded in an electrical insulator, and the first electrode 812 and the second electrode 814 are located at the back of the human body. ) May be disposed, and the ground electrode 816 may be disposed at a hip portion. In this case, the bioelectric signal may further include a breathing signal.

The first and second shear amplifier circuits are provided with a first amplifier 251 for receiving the biopotential (Vs) of the human body as a positive input terminal and transmitting them to an output terminal, and an output terminal and / or ground of the first amplifier 251. A bias circuit 253 disposed between the GND and the positive input terminal of the first amplifier 251 to ensure stable operation of the first amplifier 251. The negative input terminal of the first amplifier 251 may be directly connected to the output terminal of the first amplifier 251. The gain of the first amplifier 251 is 1, and the first amplifier may be configured as a voltage follower.

The resistive feedback circuit 270 is disposed between the positive input terminal of the first amplifier 251 and the output terminal of the first amplifier 251, and receives the output signal of the output terminal of the first amplifier 251. The resistive feedback current may be provided to the positive input terminal of the first amplifier 251 to increase the equivalent input resistance Re of the first amplifier 251.

The capacitive feedback circuit 280 is disposed between the positive input terminal of the first amplifier 251 and the output terminal of the first amplifier 251, and receives the output signal of the output terminal of the first amplifier 251. By providing a capacitive feedback current to the positive input terminal of the first amplifier 251, the equivalent input capacitance Ce of the first amplifier 251 may be reduced.

The first coupling capacitor 204a may be disposed between the first electrode 812 and the first shear amplifier circuit 822. The second coupling capacitor 204b may be disposed between the second electrode 814 and the second shear amplifier circuit 824. The first coupling capacitor 204a and the second coupling capacitor 204b may reduce signal noise due to relative movement between the human skin and the first and second electrodes 812 and 814.

The first guard part 206a may be a surface of one surface of the first electrode 812 connected to the first coupling capacitor 204a, a conductive line connecting the first electrode 812 and the first coupling capacitor 204a, And surround the first coupling capacitor 204a.

The second guard part 206b is one surface of the second electrode 814 connected to the second coupling capacitor 204b, a conductive line connecting the second electrode 814 and the second coupling capacitor 204b, And surround the second coupling capacitor 204b. The first guard portion 206a and the second guard portion 206b are respectively connected to the output of the first amplifier and driven at the same potential as the first output signal Vo1 and the second output signal Vo2, respectively. Can be.

The differential amplifier 826 may have a high frequency filter function to remove an input DC component. Outputs Vo1 and Vo2 of the first and second front end amplifier circuits 822 and 824 are provided as inputs to the differential amplifier 826. The differential amplifier 826 may include a circuit element for removing a DC offset that may exist at the outputs Vo1 and Vo2 of the first and second shear amplifier circuits. The differential amplifier 826 may output the bioelectric signal V _E in which the common mode voltage is suppressed.

The analog signal processor 831 may remove noise from the output signal V _E of the differential amplifier 826. The analog signal processor 831 is provided with an output signal of the band elimination filter 832 and the band elimination filter 832, which receives and outputs the output signal V _E of the differential amplifier 826 as an input. A high pass filter 834 for receiving and outputting, a low pass filter 836 for receiving and outputting an output signal of the high pass filter 834 as an input, and adjusting the output signal size of the low pass filter 836 to output the control signal. May include an amplifier 838.

The band reject filter 832 may remove commercial power frequency component (60 or 50 Hz) noise. The cutoff frequency of the high pass filter 834 may vary depending on the type of the bioelectrical signal, and in the case of an electrocardiogram signal, may be 0.1 Hz. The cutoff frequency of the low pass filter 836 may vary according to the type of the bioelectrical signal, and may be 150 Hz for an ECG signal.

The band cancellation filter 832 may reduce commercial power noise included in the output signal V _E of the differential amplifier 826. The high frequency pass filter 834 may remove a DC component or a low frequency fluctuation noise included in the output signal V _E. The low pass filter 836 may remove noise of high frequency components included in the output signal V _E.

The amplifier 838 may increase the size of the signal sufficiently for analog-digital signal conversion. The amplifier 838 adjusts the size of the analog signal for digital conversion. The output signal V _ECG of the amplifier has a form of a complete bioelectrical signal (eg, an electrocardiogram signal).

The digital processor 872 may analog-to-digital convert the output signal of the analog signal processor 831, process the digital signal converted into digital, and transmit data to the controller (not shown) by wire or wirelessly. The controller may include a computer. The digital processor 872 may digitally convert the output signal of the amplifier 838. The controller may display a digital signal and / or perform an additional operation.

The output signal of the digital processing unit 872 may be transmitted through a wired USB port or may be transmitted to the control unit in a wireless form such as Bluetooth. When transmitting through the USB port, the internal power of the controller may be provided to the biosignal measuring apparatus through the USB port. On the other hand, in the case of wireless transmission, the measuring device may include a battery or a wireless power transmission means.

The bioelectrical signal V _E may be stably secured when the subject is stably in close contact with the electrodes 812 and 814 without movement. The measuring device may use coupling capacitors 204a and 204b to reduce signal fluctuations caused by subject movement. Nevertheless, the subject fluctuation may affect the bioelectrical signal V _E. The subject's fluctuations make it difficult to detect an ECG-based heartbeat signal.

Therefore, a powerful means for suppressing signal fluctuations in the low frequency band is required. Means for relatively low suppression of low frequency components contained in the bioelectrical signal V _E and high frequency components (electrocardiogram R peaks) are required. The signal processing scheme that performs that function is the time derivative of the signal.

In order to detect the peak of the ECG signal, the band removing filter 832 may remove power supply noise from the output signal V _E of the differential amplifier 826.

The differential circuit unit 842 may receive an output signal of the band pass filter 832 as an input and perform differential processing. The low pass filter 846 may receive an output signal of the differential circuit unit 842 as an input to remove noise of a high frequency component. The low pass filter 846 may output a time differential ECG signal DV _ECG .

The differential circuit unit 842 may perform time differential of at least one order from the output signal of the band pass filter 832. The output signal of the differential circuit 842 may be low pass filtered. The time differential ECG signal DV _ECG has a different form from the intact traditional ECG signal. The time differential ECG signal DV _ECG may be converted into a digital signal through the digital processor 872 to be displayed and / or utilized together with the ECG signal.

The peak detector 848 may receive the output signal DV _ECG of the low pass filter 846 as an input and detect a peak of the time differential ECG signal DV _ECG . The time differential ECG signal DV _ECG has a stable characteristic. Therefore, it can be utilized as a signal source for obtaining the heartbeat pulse signal V _HBP . The peak detector 848 may generate a heartbeat pulse signal V _HBP having a rising or falling edge in synchronization with the R peak of an electrocardiogram from the time differential ECG signal DV _ECG . The heart rate pulse signal V _HBP provides a heart rate variability (HRV) signal at that interval. Autonomic nervous system information can be identified through analysis of HRV signals. The heartbeat pulse signal V _HBP may be provided to the digital processor 872. The generation of the HRV signal and the analysis of the signal may be performed by the digital processor 872 or the controller.

The measuring device may include an acceleration sensor 852 disposed around the first electrode 812 and the second electrode 814. The acceleration sensor 852 may be a three-axis acceleration sensor. The acceleration sensor 852 may detect a movement of a subject. The digital processor 872 or the controller may receive the output signal of the acceleration sensor 852 to remove motion noise included in the bioelectrical signals V _E and V _ECG .

The acceleration sensor 852 may provide a signal for analyzing the behavior of the examinee. The output of the acceleration sensor 852 may be transmitted to the digital processing unit 872 via a signal adjusting unit 8644 for adjusting the size thereof.

Some of the output signals of the acceleration sensor 852 and / or the differential amplifier output signal V _E may be input to the attachment detector 856. The attachment detecting unit 856 compares a part of the output signal of the acceleration sensor 852 and / or each amplitude of the differential amplifying unit output signal V _E with a respective reference value and meets an appropriate standard, respectively. It is determined that 801 is correctly seated on the first electrode 812, the second electrode 814, and the ground electrode 816.

The attachment detector 856 may determine whether to sit and provide a seat detection signal to the digital processor 872. The seating detection signal may be used for controlling the property of an application program utilizing the biosignal measuring apparatus, determining the sensor failure.

The vibration frequency detector (not shown) may detect the vibration frequency of the output signal V _Z of the acceleration sensor. The band elimination filter may remove the vibration frequency from the bioelectric signals V _E and V _ECG . Accordingly, motion noise included in the bioelectric signals V _E and V _ECG may be removed. The vibration frequency detector and the band elimination filter may be configured to exist inside the digital processor 872 or may exist within the controller. The removal of the vibration frequency may be useful when the biosignal measuring apparatus is mounted on the moving means.

The measuring device may include a vibrator 862 that provides a direct stimulus to the subject seated on the electrode. An application program providing the stimulus may be mounted in the digital signal processor and / or the controller. The vibrator may be disposed around the electrode and driven by the vibrator driver 864.

The vibrator 862 may provide a direct mechanical stimulus to the subject. From the intensity, frequency, and pattern of the stimulus, the subject can grasp the contents of the stimulus presented by the application. For example, the degree of relaxation according to parasympathetic nerve activity can be known from the analysis of the HRV signal. The application can determine whether there is a high degree of relaxation drowsiness. Therefore, the vibrator 862 may be used as a warning means for preventing drowsiness. In addition, when the body and the electrode are not in close contact, the vibrator 862 may warn the subject. The vibration driver 864 may receive the control signal from the digital processor 872 to drive the vibrator 862.

According to a modified embodiment of the present invention, the output signal V _E of the differential amplifier 826 may be directly converted into a digital signal and filtered by an application program.

According to a modified embodiment of the present invention, the analog signal processor includes a band cancellation filter for removing noise of commercial power frequency components included in the output signal of the differential amplifier, a DC offset included in the output of the band removing filter and a low value. And a high frequency pass filter for removing fluctuation noise of frequency components, a low pass filter for removing noise of high frequency components included in the high frequency pass filter, and an amplifier for adjusting an output signal size of the low pass filter. The biosignal measuring apparatus may measure an electroencephalogram signal by setting a cutoff frequency of the low pass filter to 50 Hz or less. The first electrode, the second electrode, and the ground electrode are embedded in an electrical insulator and mounted on the head of the human body.

According to a modified embodiment of the present invention, the analog signal processor includes a band cancellation filter for removing noise of commercial power frequency components included in the output signal of the differential amplifier, a DC offset included in the output of the band removing filter and a low value. And a high frequency pass filter for removing fluctuation noise of frequency components, a low pass filter for removing noise of high frequency components included in the high frequency pass filter, and an amplifier for adjusting an output signal size of the low pass filter. The biosignal measuring apparatus measures an EMG signal by setting a cutoff frequency of the low pass filter to 500 Hz or less. The first electrode, the second electrode, and the ground electrode are embedded in an electrical insulator and mounted on the muscle part of the human body.

14 is a diagram illustrating a differential amplifier circuit 826 according to an embodiment of the present invention.

Referring to FIG. 14, the differential amplifier circuit 826 may change the differential signal gain without affecting the common mode rejection ratio (CMRR) of the circuit.

The differential amplifier circuit 826 may include a first resistor R1 and 922 connecting a first operational amplifier 910, a first positive input terminal 911 of the first operational amplifier 910, and a first signal V1. ), A second resistor (R2,924) connected to the first positive input terminal (911) of the first operational amplifier 910, the second resistor (R2,924) and the first of the first operational amplifier (910) A gain converter 900 connected between the first output terminal 913 and including a first reference voltage Vr1, a first negative input terminal 912 and a second signal V2 of the first operational amplifier 910; The third resistor (R3,926) for connecting the second resistor, and the fourth resistor (R4, 228) for connecting the first negative input terminal 912 and the second reference voltage (Vr2) of the first operational amplifier 910 It includes. The gain converter 300 may include a second operational amplifier 930, a second negative input terminal 932 of the second operational amplifier 930, and a first output terminal 913 of the first operational amplifier 910. A first impedance Z1 and 950 to be connected, and a second impedance Z2 and 940 connected to the second negative input terminal 932 and the second output terminal 933 of the second operational amplifier 930. do. The second positive input terminal 931 of the second operational amplifier 930 is connected to the first reference voltage Vr1, and the second resistors R2 and 924 are connected to the second operational amplifier 930. 2 is connected to the output terminal 933.

The input / output transfer function of the differential amplifier circuit 826 is as follows.

Here, the conditions that the third resistor (R3, 826) and the fourth resistor (R4, 828) are the same as the first resistor (R1, 822) and the second resistor (R2, 824), respectively. When this condition is satisfied, the common mode voltage cancellation ratio CMRR of the differential amplifier circuit 826 is equal to the self common mode voltage cancellation ratio CMRR ₀ of the amplifier element used.

Referring to Equation 6, the gain of the differential signal (V1-V2) is the ratio of the resistance ratio (R2 / R1) of the second resistor 824 to the first resistor 822, and the second impedance (840) It depends on the impedance ratio Z1 / Z2 of one impedance 850. When the impedance ratio Z1 / Z2 is adjusted, the gain of the differential amplifier circuit 826 may be changed, and the common mode voltage cancellation ratio CMRR of the differential amplifier circuit 826 may not be affected.

Referring to Equation 6, a case in which the DC offset is included in the differential signals V1-V2 will be described. In this case, according to the adjustment of the first and second reference voltages Vr1 and Vr2, the output of the first operational amplifier 810 may perform a differential amplification operation without being saturated.

When it is necessary to include an arbitrary signal including a direct current in the output V _OUT , the first and second reference voltages Vr1 and Vr2 may be connected to the arbitrary signal. Specifically, the DC signal may be included in the output signal V _OUT of the differential amplifier circuit 826 using a single power supply, or floated as a DC reference voltage for digital conversion. It can be used to perform signal processing.

The differential amplifying circuit 826 may be used as a differential amplifying circuit and / or a filter circuit according to a method of configuring impedances Z1 and Z2. That is, the differential amplifying circuit 826 can effectively suppress the influence of the DC component included in the input and process the DC signal to include any signal as well as the DC as needed. In addition, the differential amplifier circuit 826 can change the gain without affecting the CMRR. At the same time, the differential amplifier circuit 826 may serve as an input signal filter.

Depending on the configuration of the impedances Z1 and Z2, the filter characteristic of the differential amplifier circuit 826 may vary. When the impedances Z1 and Z2 are composed of only resistors, the differential amplifier circuit 826 performs only a simple amplification function. However, when the impedances Z1 and Z2 are composed of a combination of a resistor and a capacitor, the differential amplifier circuit 826 may include a high pass filter (HPF), a low pass peter (LPF), a band pass filter (BPF), or Act as a band reject filter (BEF) or the like.

15 is a view for explaining a measuring device according to another embodiment of the present invention. Descriptions overlapping with those described in FIG. 13 will be omitted.

Referring to FIG. 15, an output of a driven-right-leg circuit DRL 890 may be connected to the ground electrode. The first output signal Vo1 of the first front end amplifier circuit 822 and the second output signal Vo2 of the second front end amplifier circuit 824 are provided as inputs of the DRL circuit 890. The DRL circuit 890 may be configured with an addition inversion amplifier circuit for inputting the first output signal Vo1 and the second output signal Vo2.

16 is a view for explaining a measuring device according to another embodiment of the present invention. Descriptions overlapping with those described in FIG. 13 will be omitted.

Referring to FIG. 16, the measuring device may be spaced apart from the first electrode 812 and the first electrode 812, which is not in direct electrical contact with the human body 801, and may not directly contact the human body 801. The second electrode 814, the first electrode 812, and the second electrode 814, which are disposed to be spaced apart from each other, and are not directly in contact with the human body 801. A first shear amplifier 822 connected to the 812, a second shear amplifier 824 connected to the second electrode 822, a first output signal Vo1 of the first shear amplifier 822, and And a differential amplifier 826 extracting the bioelectrical signal V _E using the second output signal Vo2 of the second front end amplifier 824.

The breath extracting unit 881 receives an output signal V _E of the differential amplifier 826 and outputs a breathing signal V _RSP . In order to extract the respiration signal V _RSP , the first electrode 812 and the second electrode 814 are mounted on the chest or the back of the human body. However, the ground electrode 816 may be mounted at any portion.

The respiration extractor 881 receives the output signal V _E of the differential amplifier 826 and inputs an output signal of the low pass filter 882 and the low pass filter 882 to extract low frequency components. It may include a high-frequency pass filter 884 provided to remove the DC component, and an amplifier 886 for receiving the output signal of the high-frequency pass filter 884 as an input to adjust the magnitude of the signal.

Due to the movement of the chest part due to breathing, the distance between the human skin and the electrodes 812 and 814 changes. Therefore, a change in the equivalent capacitance Cs formed by the human skin and the electrodes 812 and 814 occurs. Accordingly, when the electrodes 812 and 814 are positioned on the chest or the back, the respiration signal V _RSP may be detected.

The output signal V _E of the differential amplifier 826 includes a breathing signal V _RSP . Respiratory signals have relatively low frequency components (approximately 0.24 Hz level). Other biological signals (eg, ECG signals V _ECG ) have relatively high frequency components (0.5 Hz or more, 150 Hz or less). Therefore, a respiration signal may be extracted using the low pass filter 882. In the output signal V _E of the differential amplifier 826, the low pass filter 882, the high frequency pass filter 884 for removing a DC component, and a respiration signal V _RSP through an amplifier 886 for adjusting the signal size. Is obtained. The respiration signal V _RSP may be provided to the digital processing unit 872, converted into a digital signal, and utilized.

The breathing signal V _RSP is detected as a relative movement between the human skin and the electrodes 812, 814. Thus, the respiratory signal V _RSP is particularly sensitive to subject movement. The breathing signal V _RSP is preferably measured while the subject is sleeping or in a comfortable stable state.

17A and 17B are diagrams illustrating a measuring apparatus according to an embodiment of the present invention. FIG. 17B is a cross-sectional view taken along the line II ′ of FIG. 17A.

17A and 17B, an electrode structure 809 may include a first insulating layer 811a, a second insulating layer 811b disposed on the first insulating layer 811a, and the first insulating layer 811a. ) And the first electrode 812 interposed between the second insulating layer 811b and the first electrode 812, and are spaced apart from each other, and the first insulating layer 811a and the second insulating layer ( The second electrode 814 is interposed between 811b.

The ground electrode 816 may be spaced apart from the first electrode 812 and the second electrode 814 to be interposed between the first insulating layer 811a and the second insulating layer 811b. The first electrode 812, the second electrode 814, and the ground electrode 816 may be made of the same material. The first electrode 812 may be a conductive fabric or a conductive plate.

 The electrode structure 809 may be transformed into a cushion, a sheet, or a pseudo cover. The first electrode 812, the second electrode 814, and the ground electrode 816 may be embedded in a cushion, a chair, a bed, an incubator, a band, or the like.

The electrode structure 809 may include a connector 817. Connection lines may connect the electrodes 812, 814, 816 and the connector 817.

The electrodes 812, 814, 816 may be connected to the processor 803. The processor 803 may include a front end amplifier and a differential amplifier. The processing unit 803 and the connector 817 may be connected by conductors. The processor 803 may process input signals and convert the processed signals into digital signals. The digital signal may be transmitted to the controller 805 through wired / wireless communication. The controller 805 may perform additional signal processing and display the processing result.

18 is a view for explaining a measuring device according to an embodiment of the present invention.

17A, 17B, and 18, the electrode structure 809 may include a first insulating layer 811a, a second insulating layer 811b disposed on the first insulating layer 811a, and the first insulating layer 811a. The first electrode 812 interposed between the insulating layer 811a and the second insulating layer 811b, and is spaced apart from the first electrode 812. The first insulating layer 811a and the first insulating layer 811a are disposed to be spaced apart from each other. The second electrode 814 is interposed between the two insulating layers 811b. The ground electrode 816 may be spaced apart from the first electrode 812 and the second electrode 814 to be interposed between the first insulating layer 811a and the second insulating layer 811b.

The electrodes 812, 814, 816 may be connected to the processor 803. The processor 803 may be directly mounted to the electrode structure 809. The processor 803 may include a shear amplifier and a differential amplifier. The processor 803 may process input signals and convert the processed signals into digital signals. The digital signal may be transmitted to the controller 805 through wired / wireless communication. The controller 805 may perform additional signal processing and display the processing result.

19 illustrates the electrode structure 809 of FIG. 18 in a cushion form, and the cushion structure electrode structure is placed in an office chair in an office environment by using the measuring device of FIG. 13. It is a time differential ECG signal (DV _ECG ) and its heart rate pulse signal measured while dressed.

The time differential ECG signal DV _ECG is stable. In addition, the peak detector 848 forms a heartbeat pulse signal V _HBP using the time differential ECG signal DV _ECG . The heartbeat pulse signal V _HBP is stably generated.

20A to 20D illustrate the acceleration sensor output signal (z-axis output signal) and the acceleration sensor output signal measured while moving the vehicle while the driver is seated with clothes on the seat of the cushion-shaped electrode structure in the driver's seat. The signal obtained by applying the band elimination filter at the center frequency of the time differential ECG signal and the time differential ECG signal obtained by the band elimination filter at the center frequency of the acceleration sensor output signal.

13 and 20A, signals were measured using electrodes embedded in a cushion of a vehicle.

The acceleration signal Vz in the z-axis direction of the acceleration sensor 852 vibrates with a vibration frequency to be identified by vibration of the vehicle. The vibration frequency of the vehicle may adversely affect the ECG signal. Therefore, the controller (for example, the computer) may extract the vibration frequency from the acceleration signal in the z-axis direction. The control unit may include a band removing filter for removing the vibration frequency.

The time differential ECG signal (DV _ECG ) was obtained by starting the car and sitting in the driver's seat while the engine was running at approximately 1600 rpm. The mechanical movement caused by the operation of the automobile engine flows into the detection biosignal as noise. The time differential ECG signal passing through the band elimination filter extracting a vibration frequency to the output signal of the acceleration sensor 852 and removing the vibration frequency may provide a stable heartbeat pulse.

The band pass filter may receive a time differential ECG signal DV _ECG and output a filtered output signal. The filtered time differential ECG signal may stably provide a heartbeat pulse. Therefore, even when the vibration is severe, such as a vehicle, the electrocardiogram device according to an embodiment of the present invention can provide stable electrocardiogram signals.

[Embodiments for Contactless Biosignal Detection]

21 is a view illustrating a cushion for measuring a living body signal according to an embodiment of the present invention.

13, 21, 17A, and 17B, the cushion 1001 may include a first insulating layer 811a, a second insulating layer 811b disposed on the first insulating layer 811a, A first electrode 812 interposed between the first insulating layer 811a and the second insulating layer 811b and not directly in electrical contact with the human body, the first insulating layer 811a, and the second insulating layer A second electrode 814 is disposed spaced apart from the first electrode 812 interposed between the 811b and does not directly contact the human body. A ground electrode spaced apart from the first electrode 812 and the second electrode 814 and interposed between the first insulating layer 811a and the second insulating layer 811b so as not to directly contact the human body. 816 may be further included. The first electrode 812 is connected to the first shear amplifier circuit 822, the second electrode 814 is connected to the second shear amplifier circuit 824, and the first shear amplifier circuit 822 of FIG. The biosignal (ECG signal, heart rate, heart rate) may be extracted using the first output signal Vo1 and the second output signal Vo2 of the second front end amplifier circuit 822. The cushion 1001 may be disposed in the chair 1002. The cushion 1001 is not limited to being mounted on a chair. The processor 803 may be mounted on the cushion 1001.

Two measuring electrodes 812 and 814 having a sufficient size to obtain an electrically contactless cushioned electrocardiogram signal may be arranged to lie in the left and right thigh portions, respectively. In addition, the ground electrode 816 having a larger size than the measurement electrodes 812 and 814 may be disposed at the hip part or the left / right thigh part.

The ground electrode 816 may reduce power frequency impedance by increasing an equivalent capacitance between the human body and the earth ground. Thus, the ground electrode 816 serves to reduce the magnitude of power noise induced by the human body. The ground electrode 816 should be as large as possible to increase the equivalent capacitance between the earth ground and the human body.

13 and 15 to 16, the first electrode 812 and the second electrode 814 are connected to the processing unit 803 through coaxial lines, respectively. The center line of the coaxial line is connected to the coupling capacitors 204a and 204b. The coaxial shield portion is connected to the output of the shear amplifier circuit to form a guard. Ground electrode 816 is connected to the ground of shear amplifier circuits 822 and 824. Outputs of the respective shear amplifier circuits 822 and 824 connected to the first electrode 812 and the second electrode 814 are connected to the differential amplifier 826. The differential amplifier 826 provides a biosignal (electrocardiogram signal, respiration, heart rate, heart rate).

The user can sit on the cushion sensor and perform daily tasks. Clinical ECG signals contain very low frequency components, so to get a clear signal you should sit still in the chair where the sensor is placed, if possible. The clinical electrocardiogram signal is obtained only in a special place such as a hospital, and in most everyday office or rest environments, a heart rate interval variability (HRV) caused by a heartbeat pulse is much more useful than a realistic clinical electrocardiogram signal. The heart rate pulse signal is obtained from the differential-ECG signal.

22 is a diagram illustrating a chair for measuring a living body signal according to an embodiment of the present invention.

Referring to FIG. 22, the chair 1003 for measuring a non-contact biosignal is embedded in a chair 1002, a part of the chair 1002, and the first electrode 812, which does not directly contact the human body, and the chair 1002. ) And a second electrode 8134 embedded in the first electrode 812 and spaced apart from the first electrode 812 and not directly in electrical contact with the human body. The electronic device may further include a ground electrode 816 disposed to be spaced apart from the first electrode 812 and the second electrode 814 and not directly in electrical contact with the human body. The first electrode 812 is connected to a first front end amplification circuit, the second electrode 816 is connected to a second front end amplification circuit, and the first output signal and the second front end of the first front end amplification circuit. The biosignal (ecg signal, heart rate, heart rate) is extracted using the second output signal of the amplifying circuit. The processor 803 may be mounted on the chair 1002.

FIG. 23 is a diagram for explaining a biosignal measuring sheet according to an exemplary embodiment.

Referring to FIG. 23, the sheet 1001a may include electrodes 812, 814, and 186. The seat is arranged in a chair. The first electrode 812 and the second electrode 814 may be disposed at the backrest portion to provide an electrocardiogram signal and / or a respiration signal. The ground electrode 186 may be mounted at an area to be adjacent to the hip. The seat 1001a is not limited to being mounted on a chair. The processor 803 may be mounted on the sheet 1001a.

According to a modified embodiment of the present invention, as in FIG. 22, the electrodes may be configured to be embedded in a chair. At this time, the measurement electrode is embedded in the back portion of the chair, the ground electrode is embedded in the sitting portion of the chair. This structure should be treated equally.

24 is a diagram illustrating a vehicle chair for measuring a living body signal, according to an exemplary embodiment.

Referring to FIG. 24, an electrode is embedded in the chair 2003. There are two ways of embedding in a vehicle chair. One is to place the electrodes only on the hip, and the other is to place the measuring electrode on the back and the ground electrode on the hip.

25 is a diagram illustrating a bed for measuring a living body signal according to an embodiment of the present invention.

Referring to FIG. 25, the non-contact biosignal measuring bed 3003 is embedded in a bed, the first electrode 812, which is embedded in the bed 3002, and does not directly contact the human body, and is embedded in the bed 3002. And a second electrode 814 spaced apart from the first electrode 812 and not in direct electrical contact with the human body. The electronic device may further include a ground electrode 816 disposed to be spaced apart from the first electrode 812 and the second electrode 814 and not directly in electrical contact with the human body.

The first electrode 812 is connected to a first shear amplifier circuit, the second electrode 814 is connected to a second shear amplifier circuit, and the first output signal and the second front end of the first shear amplifier circuit. The biological signal (ecg signal, respiration, heart rate, heart rate) is extracted using the second output signal of the amplifying circuit. The processor 803 may be installed at one side of the bed 3002. The electrodes 812, 814, 816 may be connected to the processor 803. The processor 803 may include a shear amplifier and a differential amplifier.

The processor 803 may process input signals and convert the processed signals into digital signals. The digital signal may be transmitted to the controller through wired / wireless communication. The controller may perform additional signal processing and display the processing result.

According to a modified embodiment of the present invention, the biosignal measuring apparatus may be modified in the form of a bed cover.

FIG. 26 illustrates an incubator for measuring a living body signal, according to an exemplary embodiment.

Referring to FIG. 26, an incubator 4003 for measuring a non-contact biosignal is embedded in an incubator 4002, an incubator 4002, and in a first electrode 812, which does not directly contact the human body, in the incubator 4002. And a second electrode 814 buried and spaced apart from the first electrode 812 and not in direct electrical contact with the human body. The electronic device may further include a ground electrode 816 disposed to be spaced apart from the first electrode 812 and the second electrode 814 and not directly in electrical contact with the human body. The first electrode 812 is connected to a first shear amplifier circuit, the second electrode 814 is connected to a second shear amplifier circuit, and the first output signal and the second front end of the first shear amplifier circuit. The biological signal (ecg signal, respiration, heart rate, heart rate) is extracted using the second output signal of the amplifying circuit.

The electrodes 812, 814, 816 may be connected to a processor (not shown). The processing unit may be mounted directly to the incubator. The processor may include a shear amplifier and a differential amplifier. The processor may process input signals and convert the processed signals into digital signals. The digital signal may be transmitted to the controller through wired / wireless communication. The controller may perform additional signal processing and display the processing result.

FIG. 27 is a diagram illustrating a biosignal measurement band according to an embodiment of the present invention. FIG.

 Referring to FIG. 27, the band 5003 for non-contact biosignal measurement may include a band 5002, a first electrode 812 embedded in the band 5002, and a band 5002 that do not directly contact the human body. A second electrode 814 is embedded and spaced apart from the first electrode 812 and does not directly contact the human body. The electronic device may further include a ground electrode 816 disposed to be spaced apart from the first electrode 812 and the second electrode 814 and not directly in electrical contact with the human body. The first electrode 812 is connected to a first shear amplifier circuit, the second electrode 814 is connected to a second shear amplifier circuit, and the first output signal and the second front end of the first shear amplifier circuit. The biosignal is extracted using the second output signal of the amplifying circuit.

The band 5002 may be partially or fully stretched. The band 5002 may be circular or band-shaped. In the case of a band, the band may include coupling means 5005a and 500b for coupling both ends. The coupling means 5005a and 500b may comprise a velcro.

The electrodes 812, 814, 816 may be connected to the processor 803. The processor 803 may be directly mounted to the band. The processor 803 may include a shear amplifier and a differential amplifier. The processor may process input signals and convert the processed signals into digital signals. The digital signal may be transmitted to the controller through wired / wireless communication. The controller may perform additional signal processing and display the processing result.

Hereinafter, a biosignal measuring method according to an exemplary embodiment of the present invention will be described.

Referring back to FIG. 13, the biosignal measuring method includes a first electrode that is not in direct electrical contact with a human body and a second electrode that is spaced apart from the first electrode and is not in direct electrical contact with the human body. And disposing a ground electrode spaced apart from the second electrode and not directly in electrical contact with the human body, receiving a measurement signal of the first electrode to generate a first shear amplification signal, and the second electrode. Generating a second shear amplified signal by receiving a measurement signal of the second signal; and extracting a bioelectrical signal by using a difference between the first shear amplified signal and the second shear amplified signal.

In the attachment detection step, the bioelectrical signal is received as an input and the amplitude is compared with a reference value to determine whether the first and second electrodes are adjacent to the human body.

The biosignal measuring method may include: removing a power frequency band from the bioelectrical signal, extracting a differential ECG signal by differentiating the bioelectrical signal from which the power frequency band has been removed, and using a differential extension signal; It may include the step of detecting.

The biosignal measuring method includes applying a low pass filter to remove a high frequency component from the bioelectrical signal, and extracting a respiration signal by applying a high pass filter to remove a direct current component from the bioelectric signal from which the high frequency component has been removed. It may include a step.

The biosignal measuring method may include removing noise from the bioelectrical signal, converting the bioelectrical signal into a digital signal, extracting a differential ECG signal by differentiating the bioelectrical signal, and using an acceleration sensor. Extracting, extracting a vibration frequency of the acceleration signal, removing the vibration frequency from the differential ECG signal, extracting a heart rate variation rate using the differential ECG signal from which the vibration frequency is removed, Determining whether to be drowsy using the heart rate variability; driving a vibration stimulator if it is determined to be drowsy; extracting a tilt signal using the acceleration sensor; using the tilt signal, the human body and the first, Determining whether the second electrode is attached, and determining the amplitude of the ECG signal. Use may further include at least one of the step of determining the first, whether or not attached to the second electrode and the human body.

FIG. 28 illustrates a respiration signal V _RSP , a time differential ECG signal DV _ECG , and a heart rate pulse signal V _HBP measured using the biosignal measuring apparatus of FIG. 15.

Referring to FIG. 28, measurements were made using a cushioned sensor in a stationary state.

29A shows results obtained using a measuring apparatus according to an embodiment of the present invention.

Referring to FIG. 29A, a respiratory signal V _RSP , a z-axis acceleration signal V _Z , a time differential ECG signal DV _ECG , and a heart rate pulse signal measured using the biosignal measuring apparatus of FIG. 15 in a vehicle driving state. (V _HBP ).

29B shows results obtained using a measuring apparatus according to an embodiment of the present invention.

Referring to FIG. 29B, a respiratory signal V _RSP , a z-axis acceleration signal V _Z , a time differential ECG signal DV _ECG , and a heart rate pulse of the vibration frequency of the vehicle of FIG. 29A processed using a band elimination filter. _{Represents the} signal V _HBP .

So far I looked at the center of the preferred embodiment for the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

201: signal source
202: measuring electrode
204: coupling capacitor
251: first amplifier
253: bias circuit
270: resistive feedback circuit
280: capacitive feedback circuit

Claims (43)

A first electrode which is not in direct electrical contact with the human body;
A second electrode disposed spaced apart from the first electrode and not directly in direct contact with the human body;
A first shear amplifier circuit connected to the first electrode;
A second shear amplifier circuit connected to the second electrode; And
A differential amplifier configured to extract a bioelectrical signal by using a first output signal of the first front end amplifier circuit and a second output signal of the second front end amplifier circuit,
The first and second shear amplifier circuits are:
A first amplifier configured to receive the biopotential of the human body through a first input and a second electrode, respectively, to a positive input terminal, and to transfer the biopotential to the output terminal; and
A bias circuit disposed between at least one of an output terminal and ground (GND) of the first amplifier and a positive input terminal of the first amplifier, to ensure safe operation of the first amplifier,
The negative input terminal of the first amplifier is directly connected to the output terminal of the first amplifier, the gain of the first amplifier is 1, the first amplifier is configured as a voltage follower (voltage follower) characterized in that the bio-signal measurement Device. delete The method according to claim 1,
The first and second shear amplifier circuits are:
A capacitive feedback circuit portion disposed between the positive input end of the first amplifier and the output end of the first amplifier to reduce an effective input capacitance of the front end amplifier circuit;
And at least one of a resistive feedback circuit portion for increasing an effective input resistance of the shear amplifier circuit in a arrangement between the positive input terminal of the first amplifier and the output terminal of the first amplifier. The method according to claim 1,
A first coupling capacitor disposed between the first electrode and the first shear amplifier circuit ;
A second coupling capacitor disposed between the second electrode and the second shear amplifier circuit ;
A first guard part surrounding a wire connecting the first electrode and the first coupling capacitor, the first coupling capacitor, and a wire connecting the first coupling capacitor and the first shear amplifier circuit ; And
At least one of a second guard portion surrounding a conductive line connecting the second electrode and the second coupling capacitor, the second coupling capacitor, and a conductive line connecting the second coupling capacitor and the second shear amplifier circuit ; Biosignal measuring apparatus comprising a. 5. The method of claim 4,
The first guard portion is driven at the same potential as the output potential of the first shear amplifier circuit ,
And the second guard portion is driven at the same potential as the output potential of the second shear amplifier circuit . The method according to claim 1,
And the differential amplifier has a high frequency filter function to remove input DC components. The method of claim 6,
The differential amplifier unit:
A first operational amplifier 910;
First resistors R1 and 922 connecting the first positive input terminal 911 and the first signal V1 of the first operational amplifier 910;
Second resistors R2 and 924 connected to a first positive input terminal 911 of the first operational amplifier 910;
A gain converter 900 connected between the second resistor (R2, 924) and the first output terminal (913) of the first operational amplifier (910) and including a first reference voltage (Vr1);
Third resistors R3 and 926 connecting the first negative input terminal 912 and the second signal V2 of the first operational amplifier 910; And
And a fourth resistor (R4, 228) connecting the first negative input terminal (912) of the first operational amplifier (910) and the second reference voltage (Vr2). The method according to claim 1,
And a ground electrode disposed to be spaced apart from the first electrode and the second electrode and not to be in direct electrical contact with the human body. The method of claim 8,
The ground electrode is a biological signal measuring device, characterized in that connected to the ground (GND). The method of claim 8,
Further comprising a driven-right-leg circuit,
The ground electrode is driven in connection with an output of the driven right-leg circuit which adds, inverts and amplifies the output of the first shear amplifier and the output of the second shear amplifier. Measuring device. The method according to claim 1,
An analog signal processor for removing noise from the output signal of the differential amplifier and adjusting a signal size; And
And a digital processor for analog-to-digital converting the output signal of the analog signal processor and processing the converted digital signal to transmit the wired or wirelessly. 12. The method of claim 11,
The analog signal processing unit:
A band removing filter for removing noise of commercial power frequency components included in the output signal of the differential amplifier;
A high frequency pass filter for removing DC offset and rocking noise included in the output of the band pass filter;
A low frequency filter for removing noise included in the high frequency filter; And
It includes an amplifier for adjusting the output signal size of the low pass filter,
And a cutoff frequency of the low pass filter is set to 150 Hz or less to measure an electrocardiogram signal. 12. The method of claim 11,
The analog signal processing unit:
A band removing filter for removing noise of commercial power frequency components included in the output signal of the differential amplifier;
A high frequency pass filter for removing DC offset and rocking noise included in the output of the band pass filter;
A low frequency filter for removing noise included in the high frequency filter; And
It includes an amplifier for adjusting the output signal size of the low pass filter,
And a cutoff frequency of the low pass filter is set to 50 Hz or less to measure an electroencephalogram signal. 12. The method of claim 11,
The analog signal processing unit:
A band removing filter for removing noise of commercial power frequency components included in the output signal of the differential amplifier;
A high frequency pass filter for removing DC offset and rocking noise included in the output of the band pass filter;
A low frequency filter for removing noise included in the high frequency filter; And
It includes an amplifier for adjusting the output signal size of the low pass filter,
And a cutoff frequency of the low pass filter is set to 500 Hz or less to measure an EMG signal. 12. The method of claim 11,
The analog signal processing unit:
A low pass filter which receives the output signal of the differential amplifier and provides a signal having a frequency component lower than a commercial power supply frequency;
A high frequency pass filter for removing direct current offset and rocking noise included in the low pass filter; And
It includes an amplifier for adjusting the output signal size of the high frequency filter,
The cut-off frequency of the low-pass filter is set to 0.5Hz or less to measure the respiratory signal. 12. The method of claim 11,
The analog signal processing unit:
A band removing filter for removing noise of commercial power frequency components included in the output signal of the differential amplifier;
A differential circuit unit which receives an output of the band elimination filter and performs a derivative operation;
A low pass filter for removing noise included in an output signal of the differential circuit unit; And
It includes an amplifier for adjusting the output signal size of the low pass filter,
And a cutoff frequency of the low pass filter is set to 150 Hz or less to measure the differential ECG signal. 17. The method of claim 16,
The differential signal measuring unit of the differential circuit is characterized in that the first order or more. 17. The method of claim 16,
And a peak detector configured to receive an output signal of the low pass filter and generate a heartbeat pulse having a rising or falling edge synchronized with a vertex of the signal.
And the digital processing unit receives the heartbeat pulse. The method according to claim 1,
The bio-electrical signal is a bio-signal measuring device, characterized in that it comprises at least one of an electrocardiogram signal, respiration signal, differential ECG signal, heart rate pulse signal. The method according to claim 1,
And an acceleration sensor disposed around the first electrode or the second electrode. 21. The method of claim 20,
An attachment detector configured to receive at least one of an output signal of the differential amplifier and an output signal of the acceleration sensor and compare each signal amplitude with a reference value to determine whether the human body is correctly seated on the first, second, and ground electrodes; Biosignal measuring apparatus comprising a. 21. The method of claim 20,
Further comprising a digital processing unit for digitally converting the output of the acceleration sensor,
The digital processing unit receives the output signal of the acceleration sensor and removes kinetic noise included in the bioelectrical signal. The method according to claim 1,
A vibrator disposed around the first electrode or the second electrode; and
Further comprising a vibration drive unit for driving the vibration unit,
The vibrating unit is a biological signal measuring apparatus, characterized in that for providing a vibration stimulation to the human skin seated on the electrodes. The method according to claim 1,
And the first electrode or the second electrode is embedded in an insulator. The method according to claim 1,
The first electrode or the second electrode is embedded in an insulator, the biological signal measuring apparatus, characterized in that mounted on the head of the human body. The method according to claim 1,
The first electrode or the second electrode is embedded in an insulator, the biosignal measuring apparatus, characterized in that mounted on the hips of the human body. The method of claim 8,
The first electrode, the second electrode, and the ground electrode are embedded in an insulator,
The first and second electrodes are disposed on the back of the human body, and the ground electrode is disposed on the hip. The method according to claim 1,
And the first electrode, the second electrode, and the ground electrode are embedded in an insulator and disposed on a muscle part of the human body. At least two electrodes that are not in direct electrical contact with the human body; And
Shear amplifier circuits connected to the electrodes, respectively;
Each of the front end amplification circuits is:
An amplifier which receives the biopotential of the human body through a positive input terminal and delivers it to an output terminal; and
A bias circuit disposed between an output end of the amplifier and a positive input end of the amplifier, to ensure stable operation of the amplifier,
The negative input of the amplifier is directly connected to the output of the amplifier, the gain of the amplifier is 1, the amplifier consists of a voltage follower,
Extracting a bioelectrical signal using a difference between output signals of the front end amplification circuits,
Each of the front end amplification circuits is:
A capacitive feedback circuit portion disposed between the positive input end of the amplifier and the output end of the amplifier to reduce the effective input capacitance of the front end amplification circuit; And
And at least one of a resistive feedback circuit portion for increasing an effective input resistance of the shear amplifier circuit in a disposition between the positive input terminal of the amplifier and the output terminal of the amplifier. Shear amplification circuits respectively connected to at least two electrodes that do not directly contact the human body; And
And a differential amplifier configured to extract a bioelectrical signal using a difference between output signals of the front end amplifier circuits.
Each of the front end amplification circuits is:
An amplifier which receives the biopotential of the human body through a positive input terminal and delivers it to an output terminal; and
A bias circuit disposed between an output end of the amplifier and a positive input end of the amplifier, to ensure stable operation of the amplifier,
The negative input of the amplifier is directly connected to the output of the amplifier, the gain of the amplifier is 1, the amplifier consists of a voltage follower,
Each of the front end amplification circuits is:
A capacitive feedback circuit portion disposed between the positive input end of the amplifier and the output end of the amplifier to reduce the effective input capacitance of the front end amplification circuit; And
And at least one of a resistive feedback circuit portion for increasing an effective input resistance of the shear amplifier circuit in a disposition between the positive input terminal of the amplifier and the output terminal of the amplifier. Shear amplification circuits respectively connected to at least two electrodes that do not directly contact the human body;
A differential amplifier for extracting a bioelectrical signal using a difference between output signals of the front end amplifier circuits;
An acceleration sensor unit attached to the human body around the electrodes; and
And a processor configured to correct the bioelectrical signal by using the output signal of the acceleration sensor unit. Shear amplification circuits respectively connected to at least two electrodes that do not directly contact the human body;
A differential amplifier for extracting a bioelectrical signal using a difference between output signals of the front end amplifier circuits;
A vibrator attached to the human body around the electrodes; and
It includes a processing unit for processing the bio-electrical signal,
And the processor drives the vibrator to apply a mechanical stimulus to the human body according to a processing result of the bioelectrical signal. A first insulating layer;
A second insulating layer disposed on the first insulating layer;
A first electrode interposed between the first insulating layer and the second insulating layer and not in direct electrical contact with a human body;
A second electrode spaced apart from the first electrode interposed between the first insulating layer and the second insulating layer and not directly in direct electrical contact with a human body;
A first shear amplifier circuit connected to the first electrode;
A second shear amplifier circuit connected to the second electrode; And
A differential amplifier configured to extract a bioelectrical signal using a first output signal of the first front end amplifier circuit and a second output signal of the second front end amplifier circuit,
Each of the front end amplification circuits is:
An amplifier which receives the biopotential of the human body through a positive input terminal and delivers it to an output terminal; and
A bias circuit disposed between an output end of the amplifier and a positive input end of the amplifier, to ensure stable operation of the amplifier,
The negative input of the amplifier is directly connected to the output of the amplifier, the gain of the amplifier is 1, the amplifier consists of a voltage follower,
Each of the front end amplification circuits is:
A capacitive feedback circuit portion disposed between the positive input end of the amplifier and the output end of the amplifier to reduce the effective input capacitance of the front end amplification circuit; And
And at least one of a resistive feedback circuit portion for increasing an effective input resistance of the shear amplifier circuit in a disposition between the positive input end of the amplifier and the output end of the amplifier. chair;
A first electrode which is not in direct electrical contact with the human body embedded in the mouth of the chair;
A second electrode embedded in the chair and spaced apart from the first electrode and not directly in electrical contact with the human body;
A first shear amplifier circuit connected to the first electrode;
A second shear amplifier circuit connected to the second electrode; And
A differential amplifier configured to extract a bioelectrical signal using a first output signal of the first front end amplifier circuit and a second output signal of the second front end amplifier circuit,
Each of the front end amplification circuits is:
An amplifier which receives the biopotential of the human body through a positive input terminal and delivers it to an output terminal; and
A bias circuit disposed between an output end of the amplifier and a positive input end of the amplifier, to ensure stable operation of the amplifier,
The negative input of the amplifier is directly connected to the output of the amplifier, the gain of the amplifier is 1, the amplifier consists of a voltage follower,
Each of the front end amplification circuits is:
A capacitive feedback circuit portion disposed between the positive input end of the amplifier and the output end of the amplifier to reduce the effective input capacitance of the front end amplification circuit; And
And at least one of a resistive feedback circuit portion for increasing an effective input resistance of the shear amplifier circuit in a disposition between the positive input terminal of the amplifier and the output terminal of the amplifier. A first insulating layer;
A second insulating layer disposed on the first insulating layer;
A first electrode interposed between the first insulating layer and the second insulating layer and not in direct electrical contact with a human body;
A second electrode spaced apart from the first electrode interposed between the first insulating layer and the second insulating layer and not directly in direct electrical contact with a human body;
A first shear amplifier circuit connected to the first electrode;
A second shear amplifier circuit connected to the second electrode; And
A differential amplifier configured to extract a bioelectrical signal using a first output signal of the first front end amplifier circuit and a second output signal of the second front end amplifier circuit,
Each of the front end amplification circuits is:
An amplifier which receives the biopotential of the human body through a positive input terminal and delivers it to an output terminal; and
A bias circuit disposed between an output end of the amplifier and a positive input end of the amplifier, to ensure stable operation of the amplifier,
The negative input of the amplifier is directly connected to the output of the amplifier, the gain of the amplifier is 1, the amplifier consists of a voltage follower,
Each of the front end amplification circuits is:
A capacitive feedback circuit portion disposed between the positive input end of the amplifier and the output end of the amplifier to reduce the effective input capacitance of the front end amplification circuit; And
And at least one of a resistive feedback circuit portion for increasing an effective input resistance of the shear amplifier circuit in a arrangement between the positive input terminal of the amplifier and the output terminal of the amplifier . bed;
A first electrode embedded in the bed and not directly in electrical contact with the human body;
A second electrode embedded in the bed and spaced apart from the first electrode and not directly in electrical contact with the human body;
A first shear amplifier circuit connected to the first electrode;
A second shear amplifier circuit connected to the second electrode; And
A differential amplifier configured to extract a bioelectrical signal using a first output signal of the first front end amplifier circuit and a second output signal of the second front end amplifier circuit,
Each of the front end amplification circuits is:
An amplifier which receives the biopotential of the human body through a positive input terminal and delivers it to an output terminal; and
A bias circuit disposed between an output end of the amplifier and a positive input end of the amplifier, to ensure stable operation of the amplifier,
The negative input of the amplifier is directly connected to the output of the amplifier, the gain of the amplifier is 1, the amplifier consists of a voltage follower,
Each of the front end amplification circuits is:
A capacitive feedback circuit portion disposed between the positive input end of the amplifier and the output end of the amplifier to reduce the effective input capacitance of the front end amplification circuit; And
And at least one of a resistive feedback circuitry for increasing the effective input resistance of the shear amplifier circuitry in a disposition between the positive input end of the amplifier and the output end of the amplifier . Incubators;
A first electrode embedded in the incubator and not directly in electrical contact with the human body;
A second electrode embedded in the incubator and spaced apart from the first electrode and not directly in electrical contact with the human body;
A first shear amplifier circuit connected to the first electrode;
A second shear amplifier circuit connected to the second electrode; And
A differential amplifier configured to extract a bioelectrical signal using a first output signal of the first front end amplifier circuit and a second output signal of the second front end amplifier circuit,
Each of the front end amplification circuits is:
An amplifier which receives the biopotential of the human body through a positive input terminal and delivers it to an output terminal; and
A bias circuit disposed between an output end of the amplifier and a positive input end of the amplifier, to ensure stable operation of the amplifier,
The negative input of the amplifier is directly connected to the output of the amplifier, the gain of the amplifier is 1, the amplifier consists of a voltage follower,
Each of the front end amplification circuits is:
A capacitive feedback circuit portion disposed between the positive input end of the amplifier and the output end of the amplifier to reduce the effective input capacitance of the front end amplification circuit; And
And an at least one of a resistive feedback circuit for increasing an effective input resistance of the shear amplifier circuit in a disposition between the positive input terminal of the amplifier and the output terminal of the amplifier . band;
A first electrode embedded in the band and not directly in electrical contact with the human body;
A second electrode embedded in the band and spaced apart from the first electrode and not directly in electrical contact with the human body;
A first shear amplifier circuit connected to the first electrode;
A second shear amplifier circuit connected to the second electrode; And
A differential amplifier configured to extract a bioelectrical signal using a first output signal of the first front end amplifier circuit and a second output signal of the second front end amplifier circuit,
Each of the front end amplification circuits is:
An amplifier which receives the biopotential of the human body through a positive input terminal and delivers it to an output terminal; and
A bias circuit disposed between an output end of the amplifier and a positive input end of the amplifier, to ensure stable operation of the amplifier,
The negative input of the amplifier is directly connected to the output of the amplifier, the gain of the amplifier is 1, the amplifier consists of a voltage follower,
Each of the front end amplification circuits is:
A capacitive feedback circuit portion disposed between the positive input end of the amplifier and the output end of the amplifier to reduce the effective input capacitance of the front end amplification circuit; And
And at least one of a resistive feedback circuit portion for increasing an effective input resistance of the shear amplifier circuit in a disposition between the positive input terminal of the amplifier and the output terminal of the amplifier . Disposing a first electrode which is not in direct electrical contact with the human body and a second electrode which is spaced apart from the first electrode and which is not in direct electrical contact with the human body;
Receiving a measurement signal of the first electrode and generating a first shear amplification signal;
Receiving a measurement signal of the second electrode and generating a second shear amplification signal; And
Extracting a bioelectrical signal using a difference between the first shear amplified signal and the second shear amplified signal;
Removing a power frequency band from the bioelectrical signal;
Extracting a differential ECG signal by differentiating the bioelectrical signal from which a power frequency band has been removed; And
And detecting the peak position by using the differential extension signal. The method of claim 39,
And an attachment detection step of receiving the bioelectrical signal as an input and comparing the amplitude with a reference value to determine whether the first and second electrodes and the human body are adjacent to each other. delete The method of claim 39,
Applying a low pass filter to remove high frequency components from the bioelectrical signal; And
And extracting a respiration signal by applying a high pass filter to remove the direct current component from the bioelectric signal from which the high frequency component has been removed. The method of claim 39,
Removing noise from the bioelectrical signal;
Converting the bioelectrical signal into a digital signal;
Extracting a differential ECG signal by differentiating the bioelectrical signal;
Extracting an acceleration signal using an acceleration sensor;
Extracting a vibration frequency of the acceleration signal;
Removing the vibration frequency from the differential electrocardiogram signal;
Extracting a heart rate variability using the differential electrocardiogram signal from which the vibration frequency is removed;
Determining sleepiness using the heart rate variability;
Driving the vibrator if it is determined to be drowsy;
Determining whether the human body and the first and second electrodes are attached by using the acceleration sensor; And
And determining at least one of attaching the human body and the first and second electrodes by using the amplitude of the bioelectrical signal.

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